[PATCH v16 00/16] arm64: untag user pointers passed to the kernel

[PATCH v16 00/16] arm64: untag user pointers passed to the kernel

[Andrey Konovalov]

=== Overview

arm64 has a feature called Top Byte Ignore, which allows to embed pointer
tags into the top byte of each pointer. Userspace programs (such as
HWASan, a memory debugging tool [1]) might use this feature and pass
tagged user pointers to the kernel through syscalls or other interfaces.

Right now the kernel is already able to handle user faults with tagged
pointers, due to these patches:

1. 81cddd65 ("arm64: traps: fix userspace cache maintenance emulation on a
             tagged pointer")
2. 7dcd9dd8 ("arm64: hw_breakpoint: fix watchpoint matching for tagged
	      pointers")
3. 276e9327 ("arm64: entry: improve data abort handling of tagged
	      pointers")

This patchset extends tagged pointer support to syscall arguments.

As per the proposed ABI change [3], tagged pointers are only allowed to be
passed to syscalls when they point to memory ranges obtained by anonymous
mmap() or sbrk() (see the patchset [3] for more details).

For non-memory syscalls this is done by untaging user pointers when the
kernel performs pointer checking to find out whether the pointer comes
from userspace (most notably in access_ok). The untagging is done only
when the pointer is being checked, the tag is preserved as the pointer
makes its way through the kernel and stays tagged when the kernel
dereferences the pointer when perfoming user memory accesses.

Memory syscalls (mprotect, etc.) don't do user memory accesses but rather
deal with memory ranges, and untagged pointers are better suited to
describe memory ranges internally. Thus for memory syscalls we untag
pointers completely when they enter the kernel.

=== Other approaches

One of the alternative approaches to untagging that was considered is to
completely strip the pointer tag as the pointer enters the kernel with
some kind of a syscall wrapper, but that won't work with the countless
number of different ioctl calls. With this approach we would need a custom
wrapper for each ioctl variation, which doesn't seem practical.

An alternative approach to untagging pointers in memory syscalls prologues
is to inspead allow tagged pointers to be passed to find_vma() (and other
vma related functions) and untag them there. Unfortunately, a lot of
find_vma() callers then compare or subtract the returned vma start and end
fields against the pointer that was being searched. Thus this approach
would still require changing all find_vma() callers.

=== Testing

The following testing approaches has been taken to find potential issues
with user pointer untagging:

1. Static testing (with sparse [2] and separately with a custom static
   analyzer based on Clang) to track casts of __user pointers to integer
   types to find places where untagging needs to be done.

2. Static testing with grep to find parts of the kernel that call
   find_vma() (and other similar functions) or directly compare against
   vm_start/vm_end fields of vma.

3. Static testing with grep to find parts of the kernel that compare
   user pointers with TASK_SIZE or other similar consts and macros.

4. Dynamic testing: adding BUG_ON(has_tag(addr)) to find_vma() and running
   a modified syzkaller version that passes tagged pointers to the kernel.

Based on the results of the testing the requried patches have been added
to the patchset.

=== Notes

This patchset is meant to be merged together with "arm64 relaxed ABI" [3].

This patchset is a prerequisite for ARM's memory tagging hardware feature
support [4].

This patchset has been merged into the Pixel 2 & 3 kernel trees and is
now being used to enable testing of Pixel phones with HWASan.

Thanks!

[1] http://clang.llvm.org/docs/HardwareAssistedAddressSanitizerDesign.html

[2] https://github.com/lucvoo/sparse-dev/commit/5f960cb10f56ec2017c128ef9d16060e0145f292

[3] https://lkml.org/lkml/2019/3/18/819

[4] https://community.arm.com/processors/b/blog/posts/arm-a-profile-architecture-2018-developments-armv85a

Changes in v16:
- Moved untagging for memory syscalls from arm64 wrappers back to generic
  code.
- Dropped untagging for the following memory syscalls: brk, mmap, munmap;
  mremap (only dropped for new_address); mmap_pgoff (not used on arm64);
  remap_file_pages (deprecated); shmat, shmdt (work on shared memory).
- Changed kselftest to LD_PRELOAD a shared library that overrides malloc
  to return tagged pointers.
- Rebased onto 5.2-rc3.

Changes in v15:
- Removed unnecessary untagging from radeon_ttm_tt_set_userptr().
- Removed unnecessary untagging from amdgpu_ttm_tt_set_userptr().
- Moved untagging to validate_range() in userfaultfd code.
- Moved untagging to ib_uverbs_(re)reg_mr() from mlx4_get_umem_mr().
- Rebased onto 5.1.

Changes in v14:
- Moved untagging for most memory syscalls to an arm64 specific
  implementation, instead of doing that in the common code.
- Dropped "net, arm64: untag user pointers in tcp_zerocopy_receive", since
  the provided user pointers don't come from an anonymous map and thus are
  not covered by this ABI relaxation.
- Dropped "kernel, arm64: untag user pointers in prctl_set_mm*".
- Moved untagging from __check_mem_type() to tee_shm_register().
- Updated untagging for the amdgpu and radeon drivers to cover the MMU
  notifier, as suggested by Felix.
- Since this ABI relaxation doesn't actually allow tagged instruction
  pointers, dropped the following patches:
- Dropped "tracing, arm64: untag user pointers in seq_print_user_ip".
- Dropped "uprobes, arm64: untag user pointers in find_active_uprobe".
- Dropped "bpf, arm64: untag user pointers in stack_map_get_build_id_offset".
- Rebased onto 5.1-rc7 (37624b58).

Changes in v13:
- Simplified untagging in tcp_zerocopy_receive().
- Looked at find_vma() callers in drivers/, which allowed to identify a
  few other places where untagging is needed.
- Added patch "mm, arm64: untag user pointers in get_vaddr_frames".
- Added patch "drm/amdgpu, arm64: untag user pointers in
  amdgpu_ttm_tt_get_user_pages".
- Added patch "drm/radeon, arm64: untag user pointers in
  radeon_ttm_tt_pin_userptr".
- Added patch "IB/mlx4, arm64: untag user pointers in mlx4_get_umem_mr".
- Added patch "media/v4l2-core, arm64: untag user pointers in
  videobuf_dma_contig_user_get".
- Added patch "tee/optee, arm64: untag user pointers in check_mem_type".
- Added patch "vfio/type1, arm64: untag user pointers".

Changes in v12:
- Changed untagging in tcp_zerocopy_receive() to also untag zc->address.
- Fixed untagging in prctl_set_mm* to only untag pointers for vma lookups
  and validity checks, but leave them as is for actual user space accesses.
- Updated the link to the v2 of the "arm64 relaxed ABI" patchset [3].
- Dropped the documentation patch, as the "arm64 relaxed ABI" patchset [3]
  handles that.

Changes in v11:
- Added "uprobes, arm64: untag user pointers in find_active_uprobe" patch.
- Added "bpf, arm64: untag user pointers in stack_map_get_build_id_offset"
  patch.
- Fixed "tracing, arm64: untag user pointers in seq_print_user_ip" to
  correctly perform subtration with a tagged addr.
- Moved untagged_addr() from SYSCALL_DEFINE3(mprotect) and
  SYSCALL_DEFINE4(pkey_mprotect) to do_mprotect_pkey().
- Moved untagged_addr() definition for other arches from
  include/linux/memory.h to include/linux/mm.h.
- Changed untagging in strn*_user() to perform userspace accesses through
  tagged pointers.
- Updated the documentation to mention that passing tagged pointers to
  memory syscalls is allowed.
- Updated the test to use malloc'ed memory instead of stack memory.

Changes in v10:
- Added "mm, arm64: untag user pointers passed to memory syscalls" back.
- New patch "fs, arm64: untag user pointers in fs/userfaultfd.c".
- New patch "net, arm64: untag user pointers in tcp_zerocopy_receive".
- New patch "kernel, arm64: untag user pointers in prctl_set_mm*".
- New patch "tracing, arm64: untag user pointers in seq_print_user_ip".

Changes in v9:
- Rebased onto 4.20-rc6.
- Used u64 instead of __u64 in type casts in the untagged_addr macro for
  arm64.
- Added braces around (addr) in the untagged_addr macro for other arches.

Changes in v8:
- Rebased onto 65102238 (4.20-rc1).
- Added a note to the cover letter on why syscall wrappers/shims that untag
  user pointers won't work.
- Added a note to the cover letter that this patchset has been merged into
  the Pixel 2 kernel tree.
- Documentation fixes, in particular added a list of syscalls that don't
  support tagged user pointers.

Changes in v7:
- Rebased onto 17b57b18 (4.19-rc6).
- Dropped the "arm64: untag user address in __do_user_fault" patch, since
  the existing patches already handle user faults properly.
- Dropped the "usb, arm64: untag user addresses in devio" patch, since the
  passed pointer must come from a vma and therefore be untagged.
- Dropped the "arm64: annotate user pointers casts detected by sparse"
  patch (see the discussion to the replies of the v6 of this patchset).
- Added more context to the cover letter.
- Updated Documentation/arm64/tagged-pointers.txt.

Changes in v6:
- Added annotations for user pointer casts found by sparse.
- Rebased onto 050cdc6c (4.19-rc1+).

Changes in v5:
- Added 3 new patches that add untagging to places found with static
  analysis.
- Rebased onto 44c929e1 (4.18-rc8).

Changes in v4:
- Added a selftest for checking that passing tagged pointers to the
  kernel succeeds.
- Rebased onto 81e97f013 (4.18-rc1+).

Changes in v3:
- Rebased onto e5c51f30 (4.17-rc6+).
- Added linux-arch@ to the list of recipients.

Changes in v2:
- Rebased onto 2d618bdf (4.17-rc3+).
- Removed excessive untagging in gup.c.
- Removed untagging pointers returned from __uaccess_mask_ptr.

Changes in v1:
- Rebased onto 4.17-rc1.

Changes in RFC v2:
- Added "#ifndef untagged_addr..." fallback in linux/uaccess.h instead of
  defining it for each arch individually.
- Updated Documentation/arm64/tagged-pointers.txt.
- Dropped "mm, arm64: untag user addresses in memory syscalls".
- Rebased onto 3eb2ce82 (4.16-rc7).

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

Andrey Konovalov (16):
  uaccess: add untagged_addr definition for other arches
  arm64: untag user pointers in access_ok and __uaccess_mask_ptr
  lib, arm64: untag user pointers in strn*_user
  mm: untag user pointers in do_pages_move
  arm64: untag user pointers passed to memory syscalls
  mm, arm64: untag user pointers in mm/gup.c
  mm, arm64: untag user pointers in get_vaddr_frames
  fs, arm64: untag user pointers in copy_mount_options
  fs, arm64: untag user pointers in fs/userfaultfd.c
  drm/amdgpu, arm64: untag user pointers
  drm/radeon, arm64: untag user pointers in radeon_gem_userptr_ioctl
  IB, arm64: untag user pointers in ib_uverbs_(re)reg_mr()
  media/v4l2-core, arm64: untag user pointers in
    videobuf_dma_contig_user_get
  tee, arm64: untag user pointers in tee_shm_register
  vfio/type1, arm64: untag user pointers in vaddr_get_pfn
  selftests, arm64: add a selftest for passing tagged pointers to kernel

 arch/arm64/include/asm/uaccess.h              | 10 +++--
 .../gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c  |  2 +-
 drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c       |  2 +
 drivers/gpu/drm/radeon/radeon_gem.c           |  2 +
 drivers/infiniband/core/uverbs_cmd.c          |  4 ++
 drivers/media/v4l2-core/videobuf-dma-contig.c |  9 ++--
 drivers/tee/tee_shm.c                         |  1 +
 drivers/vfio/vfio_iommu_type1.c               |  2 +
 fs/namespace.c                                |  2 +-
 fs/userfaultfd.c                              | 22 +++++-----
 include/linux/mm.h                            |  4 ++
 lib/strncpy_from_user.c                       |  3 +-
 lib/strnlen_user.c                            |  3 +-
 mm/frame_vector.c                             |  2 +
 mm/gup.c                                      |  4 ++
 mm/madvise.c                                  |  2 +
 mm/mempolicy.c                                |  3 ++
 mm/migrate.c                                  |  1 +
 mm/mincore.c                                  |  2 +
 mm/mlock.c                                    |  4 ++
 mm/mprotect.c                                 |  2 +
 mm/mremap.c                                   |  2 +
 mm/msync.c                                    |  2 +
 tools/testing/selftests/arm64/.gitignore      |  1 +
 tools/testing/selftests/arm64/Makefile        | 22 ++++++++++
 .../testing/selftests/arm64/run_tags_test.sh  | 12 ++++++
 tools/testing/selftests/arm64/tags_lib.c      | 42 +++++++++++++++++++
 tools/testing/selftests/arm64/tags_test.c     | 18 ++++++++
 28 files changed, 163 insertions(+), 22 deletions(-)
 create mode 100644 tools/testing/selftests/arm64/.gitignore
 create mode 100644 tools/testing/selftests/arm64/Makefile
 create mode 100755 tools/testing/selftests/arm64/run_tags_test.sh
 create mode 100644 tools/testing/selftests/arm64/tags_lib.c
 create mode 100644 tools/testing/selftests/arm64/tags_test.c

-- 
2.22.0.rc1.311.g5d7573a151-goog

[PATCH v16 01/16] uaccess: add untagged_addr definition for other arches

[Andrey Konovalov]

To allow arm64 syscalls to accept tagged pointers from userspace, we must
untag them when they are passed to the kernel. Since untagging is done in
generic parts of the kernel, the untagged_addr macro needs to be defined
for all architectures.

Define it as a noop for architectures other than arm64.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Khalid Aziz <khalid.aziz@oracle.com>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 include/linux/mm.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 0e8834ac32b7..949d43e9c0b6 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -99,6 +99,10 @@ extern int mmap_rnd_compat_bits __read_mostly;
 #include <asm/pgtable.h>
 #include <asm/processor.h>
 
+#ifndef untagged_addr
+#define untagged_addr(addr) (addr)
+#endif
+
 #ifndef __pa_symbol
 #define __pa_symbol(x)  __pa(RELOC_HIDE((unsigned long)(x), 0))
 #endif
-- 
2.22.0.rc1.311.g5d7573a151-goog

[PATCH v16 02/16] arm64: untag user pointers in access_ok and __uaccess_mask_ptr

[Andrey Konovalov]

This patch is a part of a series that extends arm64 kernel ABI to allow to
pass tagged user pointers (with the top byte set to something else other
than 0x00) as syscall arguments.

copy_from_user (and a few other similar functions) are used to copy data
from user memory into the kernel memory or vice versa. Since a user can
provided a tagged pointer to one of the syscalls that use copy_from_user,
we need to correctly handle such pointers.

Do this by untagging user pointers in access_ok and in __uaccess_mask_ptr,
before performing access validity checks.

Note, that this patch only temporarily untags the pointers to perform the
checks, but then passes them as is into the kernel internals.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 arch/arm64/include/asm/uaccess.h | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index e5d5f31c6d36..9164ecb5feca 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -94,7 +94,7 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si
 	return ret;
 }
 
-#define access_ok(addr, size)	__range_ok(addr, size)
+#define access_ok(addr, size)	__range_ok(untagged_addr(addr), size)
 #define user_addr_max			get_fs
 
 #define _ASM_EXTABLE(from, to)						\
@@ -226,7 +226,8 @@ static inline void uaccess_enable_not_uao(void)
 
 /*
  * Sanitise a uaccess pointer such that it becomes NULL if above the
- * current addr_limit.
+ * current addr_limit. In case the pointer is tagged (has the top byte set),
+ * untag the pointer before checking.
  */
 #define uaccess_mask_ptr(ptr) (__typeof__(ptr))__uaccess_mask_ptr(ptr)
 static inline void __user *__uaccess_mask_ptr(const void __user *ptr)
@@ -234,10 +235,11 @@ static inline void __user *__uaccess_mask_ptr(const void __user *ptr)
 	void __user *safe_ptr;
 
 	asm volatile(
-	"	bics	xzr, %1, %2\n"
+	"	bics	xzr, %3, %2\n"
 	"	csel	%0, %1, xzr, eq\n"
 	: "=&r" (safe_ptr)
-	: "r" (ptr), "r" (current_thread_info()->addr_limit)
+	: "r" (ptr), "r" (current_thread_info()->addr_limit),
+	  "r" (untagged_addr(ptr))
 	: "cc");
 
 	csdb();
-- 
2.22.0.rc1.311.g5d7573a151-goog

[PATCH v16 03/16] lib, arm64: untag user pointers in strn*_user

[Andrey Konovalov]

This patch is a part of a series that extends arm64 kernel ABI to allow to
pass tagged user pointers (with the top byte set to something else other
than 0x00) as syscall arguments.

strncpy_from_user and strnlen_user accept user addresses as arguments, and
do not go through the same path as copy_from_user and others, so here we
need to handle the case of tagged user addresses separately.

Untag user pointers passed to these functions.

Note, that this patch only temporarily untags the pointers to perform
validity checks, but then uses them as is to perform user memory accesses.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 lib/strncpy_from_user.c | 3 ++-
 lib/strnlen_user.c      | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/lib/strncpy_from_user.c b/lib/strncpy_from_user.c
index 023ba9f3b99f..dccb95af6003 100644
--- a/lib/strncpy_from_user.c
+++ b/lib/strncpy_from_user.c
@@ -6,6 +6,7 @@
 #include <linux/uaccess.h>
 #include <linux/kernel.h>
 #include <linux/errno.h>
+#include <linux/mm.h>
 
 #include <asm/byteorder.h>
 #include <asm/word-at-a-time.h>
@@ -108,7 +109,7 @@ long strncpy_from_user(char *dst, const char __user *src, long count)
 		return 0;
 
 	max_addr = user_addr_max();
-	src_addr = (unsigned long)src;
+	src_addr = (unsigned long)untagged_addr(src);
 	if (likely(src_addr < max_addr)) {
 		unsigned long max = max_addr - src_addr;
 		long retval;
diff --git a/lib/strnlen_user.c b/lib/strnlen_user.c
index 7f2db3fe311f..28ff554a1be8 100644
--- a/lib/strnlen_user.c
+++ b/lib/strnlen_user.c
@@ -2,6 +2,7 @@
 #include <linux/kernel.h>
 #include <linux/export.h>
 #include <linux/uaccess.h>
+#include <linux/mm.h>
 
 #include <asm/word-at-a-time.h>
 
@@ -109,7 +110,7 @@ long strnlen_user(const char __user *str, long count)
 		return 0;
 
 	max_addr = user_addr_max();
-	src_addr = (unsigned long)str;
+	src_addr = (unsigned long)untagged_addr(str);
 	if (likely(src_addr < max_addr)) {
 		unsigned long max = max_addr - src_addr;
 		long retval;
-- 
2.22.0.rc1.311.g5d7573a151-goog

[PATCH v16 04/16] mm: untag user pointers in do_pages_move

[Andrey Konovalov]

This patch is a part of a series that extends arm64 kernel ABI to allow to
pass tagged user pointers (with the top byte set to something else other
than 0x00) as syscall arguments.

do_pages_move() is used in the implementation of the move_pages syscall.

Untag user pointers in this function.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 mm/migrate.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/migrate.c b/mm/migrate.c
index f2ecc2855a12..3930bb6fa656 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1617,6 +1617,7 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
 		if (get_user(node, nodes + i))
 			goto out_flush;
 		addr = (unsigned long)p;
+		addr = untagged_addr(addr);
 
 		err = -ENODEV;
 		if (node < 0 || node >= MAX_NUMNODES)
-- 
2.22.0.rc1.311.g5d7573a151-goog

[PATCH v16 05/16] arm64: untag user pointers passed to memory syscalls

[Andrey Konovalov]

This patch is a part of a series that extends arm64 kernel ABI to allow to
pass tagged user pointers (with the top byte set to something else other
than 0x00) as syscall arguments.

This patch allows tagged pointers to be passed to the following memory
syscalls: get_mempolicy, madvise, mbind, mincore, mlock, mlock2, mprotect,
mremap, msync, munlock.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 mm/madvise.c   | 2 ++
 mm/mempolicy.c | 3 +++
 mm/mincore.c   | 2 ++
 mm/mlock.c     | 4 ++++
 mm/mprotect.c  | 2 ++
 mm/mremap.c    | 2 ++
 mm/msync.c     | 2 ++
 7 files changed, 17 insertions(+)

diff --git a/mm/madvise.c b/mm/madvise.c
index 628022e674a7..39b82f8a698f 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -810,6 +810,8 @@ SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
 	size_t len;
 	struct blk_plug plug;
 
+	start = untagged_addr(start);
+
 	if (!madvise_behavior_valid(behavior))
 		return error;
 
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 01600d80ae01..78e0a88b2680 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1360,6 +1360,7 @@ static long kernel_mbind(unsigned long start, unsigned long len,
 	int err;
 	unsigned short mode_flags;
 
+	start = untagged_addr(start);
 	mode_flags = mode & MPOL_MODE_FLAGS;
 	mode &= ~MPOL_MODE_FLAGS;
 	if (mode >= MPOL_MAX)
@@ -1517,6 +1518,8 @@ static int kernel_get_mempolicy(int __user *policy,
 	int uninitialized_var(pval);
 	nodemask_t nodes;
 
+	addr = untagged_addr(addr);
+
 	if (nmask != NULL && maxnode < nr_node_ids)
 		return -EINVAL;
 
diff --git a/mm/mincore.c b/mm/mincore.c
index c3f058bd0faf..64c322ed845c 100644
--- a/mm/mincore.c
+++ b/mm/mincore.c
@@ -249,6 +249,8 @@ SYSCALL_DEFINE3(mincore, unsigned long, start, size_t, len,
 	unsigned long pages;
 	unsigned char *tmp;
 
+	start = untagged_addr(start);
+
 	/* Check the start address: needs to be page-aligned.. */
 	if (start & ~PAGE_MASK)
 		return -EINVAL;
diff --git a/mm/mlock.c b/mm/mlock.c
index 080f3b36415b..e82609eaa428 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -674,6 +674,8 @@ static __must_check int do_mlock(unsigned long start, size_t len, vm_flags_t fla
 	unsigned long lock_limit;
 	int error = -ENOMEM;
 
+	start = untagged_addr(start);
+
 	if (!can_do_mlock())
 		return -EPERM;
 
@@ -735,6 +737,8 @@ SYSCALL_DEFINE2(munlock, unsigned long, start, size_t, len)
 {
 	int ret;
 
+	start = untagged_addr(start);
+
 	len = PAGE_ALIGN(len + (offset_in_page(start)));
 	start &= PAGE_MASK;
 
diff --git a/mm/mprotect.c b/mm/mprotect.c
index bf38dfbbb4b4..19f981b733bc 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -465,6 +465,8 @@ static int do_mprotect_pkey(unsigned long start, size_t len,
 	const bool rier = (current->personality & READ_IMPLIES_EXEC) &&
 				(prot & PROT_READ);
 
+	start = untagged_addr(start);
+
 	prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
 	if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
 		return -EINVAL;
diff --git a/mm/mremap.c b/mm/mremap.c
index fc241d23cd97..1d98281f7204 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -606,6 +606,8 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
 	LIST_HEAD(uf_unmap_early);
 	LIST_HEAD(uf_unmap);
 
+	addr = untagged_addr(addr);
+
 	if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE))
 		return ret;
 
diff --git a/mm/msync.c b/mm/msync.c
index ef30a429623a..c3bd3e75f687 100644
--- a/mm/msync.c
+++ b/mm/msync.c
@@ -37,6 +37,8 @@ SYSCALL_DEFINE3(msync, unsigned long, start, size_t, len, int, flags)
 	int unmapped_error = 0;
 	int error = -EINVAL;
 
+	start = untagged_addr(start);
+
 	if (flags & ~(MS_ASYNC | MS_INVALIDATE | MS_SYNC))
 		goto out;
 	if (offset_in_page(start))
-- 
2.22.0.rc1.311.g5d7573a151-goog

[PATCH v16 06/16] mm, arm64: untag user pointers in mm/gup.c

[Andrey Konovalov]

This patch is a part of a series that extends arm64 kernel ABI to allow to
pass tagged user pointers (with the top byte set to something else other
than 0x00) as syscall arguments.

mm/gup.c provides a kernel interface that accepts user addresses and
manipulates user pages directly (for example get_user_pages, that is used
by the futex syscall). Since a user can provided tagged addresses, we need
to handle this case.

Add untagging to gup.c functions that use user addresses for vma lookups.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 mm/gup.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/mm/gup.c b/mm/gup.c
index ddde097cf9e4..c37df3d455a2 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -802,6 +802,8 @@ static long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 	if (!nr_pages)
 		return 0;
 
+	start = untagged_addr(start);
+
 	VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET));
 
 	/*
@@ -964,6 +966,8 @@ int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm,
 	struct vm_area_struct *vma;
 	vm_fault_t ret, major = 0;
 
+	address = untagged_addr(address);
+
 	if (unlocked)
 		fault_flags |= FAULT_FLAG_ALLOW_RETRY;
 
-- 
2.22.0.rc1.311.g5d7573a151-goog

[PATCH v16 07/16] mm, arm64: untag user pointers in get_vaddr_frames

[Andrey Konovalov]

This patch is a part of a series that extends arm64 kernel ABI to allow to
pass tagged user pointers (with the top byte set to something else other
than 0x00) as syscall arguments.

get_vaddr_frames uses provided user pointers for vma lookups, which can
only by done with untagged pointers. Instead of locating and changing
all callers of this function, perform untagging in it.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 mm/frame_vector.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/frame_vector.c b/mm/frame_vector.c
index c64dca6e27c2..c431ca81dad5 100644
--- a/mm/frame_vector.c
+++ b/mm/frame_vector.c
@@ -46,6 +46,8 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames,
 	if (WARN_ON_ONCE(nr_frames > vec->nr_allocated))
 		nr_frames = vec->nr_allocated;
 
+	start = untagged_addr(start);
+
 	down_read(&mm->mmap_sem);
 	locked = 1;
 	vma = find_vma_intersection(mm, start, start + 1);
-- 
2.22.0.rc1.311.g5d7573a151-goog

[PATCH v16 08/16] fs, arm64: untag user pointers in copy_mount_options

[Andrey Konovalov]

This patch is a part of a series that extends arm64 kernel ABI to allow to
pass tagged user pointers (with the top byte set to something else other
than 0x00) as syscall arguments.

In copy_mount_options a user address is being subtracted from TASK_SIZE.
If the address is lower than TASK_SIZE, the size is calculated to not
allow the exact_copy_from_user() call to cross TASK_SIZE boundary.
However if the address is tagged, then the size will be calculated
incorrectly.

Untag the address before subtracting.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 fs/namespace.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/namespace.c b/fs/namespace.c
index b26778bdc236..2e85712a19ed 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2993,7 +2993,7 @@ void *copy_mount_options(const void __user * data)
 	 * the remainder of the page.
 	 */
 	/* copy_from_user cannot cross TASK_SIZE ! */
-	size = TASK_SIZE - (unsigned long)data;
+	size = TASK_SIZE - (unsigned long)untagged_addr(data);
 	if (size > PAGE_SIZE)
 		size = PAGE_SIZE;
 
-- 
2.22.0.rc1.311.g5d7573a151-goog

[PATCH v16 09/16] fs, arm64: untag user pointers in fs/userfaultfd.c

[Andrey Konovalov]

This patch is a part of a series that extends arm64 kernel ABI to allow to
pass tagged user pointers (with the top byte set to something else other
than 0x00) as syscall arguments.

userfaultfd code use provided user pointers for vma lookups, which can
only by done with untagged pointers.

Untag user pointers in validate_range().

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 fs/userfaultfd.c | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 3b30301c90ec..24d68c3b5ee2 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -1263,21 +1263,23 @@ static __always_inline void wake_userfault(struct userfaultfd_ctx *ctx,
 }
 
 static __always_inline int validate_range(struct mm_struct *mm,
-					  __u64 start, __u64 len)
+					  __u64 *start, __u64 len)
 {
 	__u64 task_size = mm->task_size;
 
-	if (start & ~PAGE_MASK)
+	*start = untagged_addr(*start);
+
+	if (*start & ~PAGE_MASK)
 		return -EINVAL;
 	if (len & ~PAGE_MASK)
 		return -EINVAL;
 	if (!len)
 		return -EINVAL;
-	if (start < mmap_min_addr)
+	if (*start < mmap_min_addr)
 		return -EINVAL;
-	if (start >= task_size)
+	if (*start >= task_size)
 		return -EINVAL;
-	if (len > task_size - start)
+	if (len > task_size - *start)
 		return -EINVAL;
 	return 0;
 }
@@ -1327,7 +1329,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
 		goto out;
 	}
 
-	ret = validate_range(mm, uffdio_register.range.start,
+	ret = validate_range(mm, &uffdio_register.range.start,
 			     uffdio_register.range.len);
 	if (ret)
 		goto out;
@@ -1516,7 +1518,7 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
 	if (copy_from_user(&uffdio_unregister, buf, sizeof(uffdio_unregister)))
 		goto out;
 
-	ret = validate_range(mm, uffdio_unregister.start,
+	ret = validate_range(mm, &uffdio_unregister.start,
 			     uffdio_unregister.len);
 	if (ret)
 		goto out;
@@ -1667,7 +1669,7 @@ static int userfaultfd_wake(struct userfaultfd_ctx *ctx,
 	if (copy_from_user(&uffdio_wake, buf, sizeof(uffdio_wake)))
 		goto out;
 
-	ret = validate_range(ctx->mm, uffdio_wake.start, uffdio_wake.len);
+	ret = validate_range(ctx->mm, &uffdio_wake.start, uffdio_wake.len);
 	if (ret)
 		goto out;
 
@@ -1707,7 +1709,7 @@ static int userfaultfd_copy(struct userfaultfd_ctx *ctx,
 			   sizeof(uffdio_copy)-sizeof(__s64)))
 		goto out;
 
-	ret = validate_range(ctx->mm, uffdio_copy.dst, uffdio_copy.len);
+	ret = validate_range(ctx->mm, &uffdio_copy.dst, uffdio_copy.len);
 	if (ret)
 		goto out;
 	/*
@@ -1763,7 +1765,7 @@ static int userfaultfd_zeropage(struct userfaultfd_ctx *ctx,
 			   sizeof(uffdio_zeropage)-sizeof(__s64)))
 		goto out;
 
-	ret = validate_range(ctx->mm, uffdio_zeropage.range.start,
+	ret = validate_range(ctx->mm, &uffdio_zeropage.range.start,
 			     uffdio_zeropage.range.len);
 	if (ret)
 		goto out;
-- 
2.22.0.rc1.311.g5d7573a151-goog

[PATCH v16 10/16] drm/amdgpu, arm64: untag user pointers

[Andrey Konovalov]

This patch is a part of a series that extends arm64 kernel ABI to allow to
pass tagged user pointers (with the top byte set to something else other
than 0x00) as syscall arguments.

In amdgpu_gem_userptr_ioctl() and amdgpu_amdkfd_gpuvm.c/init_user_pages()
an MMU notifier is set up with a (tagged) userspace pointer. The untagged
address should be used so that MMU notifiers for the untagged address get
correctly matched up with the right BO. This patch untag user pointers in
amdgpu_gem_userptr_ioctl() for the GEM case and in amdgpu_amdkfd_gpuvm_
alloc_memory_of_gpu() for the KFD case. This also makes sure that an
untagged pointer is passed to amdgpu_ttm_tt_get_user_pages(), which uses
it for vma lookups.

Suggested-by: Kuehling, Felix <Felix.Kuehling@amd.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 2 +-
 drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c          | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
index a6e5184d436c..5d476e9bbc43 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
@@ -1108,7 +1108,7 @@ int amdgpu_amdkfd_gpuvm_alloc_memory_of_gpu(
 		alloc_flags = 0;
 		if (!offset || !*offset)
 			return -EINVAL;
-		user_addr = *offset;
+		user_addr = untagged_addr(*offset);
 	} else if (flags & ALLOC_MEM_FLAGS_DOORBELL) {
 		domain = AMDGPU_GEM_DOMAIN_GTT;
 		alloc_domain = AMDGPU_GEM_DOMAIN_CPU;
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
index d4fcf5475464..e91df1407618 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
@@ -287,6 +287,8 @@ int amdgpu_gem_userptr_ioctl(struct drm_device *dev, void *data,
 	uint32_t handle;
 	int r;
 
+	args->addr = untagged_addr(args->addr);
+
 	if (offset_in_page(args->addr | args->size))
 		return -EINVAL;
 
-- 
2.22.0.rc1.311.g5d7573a151-goog

[PATCH v16 11/16] drm/radeon, arm64: untag user pointers in radeon_gem_userptr_ioctl

[Andrey Konovalov]

This patch is a part of a series that extends arm64 kernel ABI to allow to
pass tagged user pointers (with the top byte set to something else other
than 0x00) as syscall arguments.

In radeon_gem_userptr_ioctl() an MMU notifier is set up with a (tagged)
userspace pointer. The untagged address should be used so that MMU
notifiers for the untagged address get correctly matched up with the right
BO. This funcation also calls radeon_ttm_tt_pin_userptr(), which uses
provided user pointers for vma lookups, which can only by done with
untagged pointers.

This patch untags user pointers in radeon_gem_userptr_ioctl().

Suggested-by: Kuehling, Felix <Felix.Kuehling@amd.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 drivers/gpu/drm/radeon/radeon_gem.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/radeon/radeon_gem.c b/drivers/gpu/drm/radeon/radeon_gem.c
index 44617dec8183..90eb78fb5eb2 100644
--- a/drivers/gpu/drm/radeon/radeon_gem.c
+++ b/drivers/gpu/drm/radeon/radeon_gem.c
@@ -291,6 +291,8 @@ int radeon_gem_userptr_ioctl(struct drm_device *dev, void *data,
 	uint32_t handle;
 	int r;
 
+	args->addr = untagged_addr(args->addr);
+
 	if (offset_in_page(args->addr | args->size))
 		return -EINVAL;
 
-- 
2.22.0.rc1.311.g5d7573a151-goog

[PATCH v16 12/16] IB, arm64: untag user pointers in ib_uverbs_(re)reg_mr()

[Andrey Konovalov]

This patch is a part of a series that extends arm64 kernel ABI to allow to
pass tagged user pointers (with the top byte set to something else other
than 0x00) as syscall arguments.

ib_uverbs_(re)reg_mr() use provided user pointers for vma lookups (through
e.g. mlx4_get_umem_mr()), which can only by done with untagged pointers.

Untag user pointers in these functions.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 drivers/infiniband/core/uverbs_cmd.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c
index 5a3a1780ceea..f88ee733e617 100644
--- a/drivers/infiniband/core/uverbs_cmd.c
+++ b/drivers/infiniband/core/uverbs_cmd.c
@@ -709,6 +709,8 @@ static int ib_uverbs_reg_mr(struct uverbs_attr_bundle *attrs)
 	if (ret)
 		return ret;
 
+	cmd.start = untagged_addr(cmd.start);
+
 	if ((cmd.start & ~PAGE_MASK) != (cmd.hca_va & ~PAGE_MASK))
 		return -EINVAL;
 
@@ -791,6 +793,8 @@ static int ib_uverbs_rereg_mr(struct uverbs_attr_bundle *attrs)
 	if (ret)
 		return ret;
 
+	cmd.start = untagged_addr(cmd.start);
+
 	if (cmd.flags & ~IB_MR_REREG_SUPPORTED || !cmd.flags)
 		return -EINVAL;
 
-- 
2.22.0.rc1.311.g5d7573a151-goog

[PATCH v16 13/16] media/v4l2-core, arm64: untag user pointers in videobuf_dma_contig_user_get

[Andrey Konovalov]

This patch is a part of a series that extends arm64 kernel ABI to allow to
pass tagged user pointers (with the top byte set to something else other
than 0x00) as syscall arguments.

videobuf_dma_contig_user_get() uses provided user pointers for vma
lookups, which can only by done with untagged pointers.

Untag the pointers in this function.

Acked-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 drivers/media/v4l2-core/videobuf-dma-contig.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/media/v4l2-core/videobuf-dma-contig.c b/drivers/media/v4l2-core/videobuf-dma-contig.c
index e1bf50df4c70..8a1ddd146b17 100644
--- a/drivers/media/v4l2-core/videobuf-dma-contig.c
+++ b/drivers/media/v4l2-core/videobuf-dma-contig.c
@@ -160,6 +160,7 @@ static void videobuf_dma_contig_user_put(struct videobuf_dma_contig_memory *mem)
 static int videobuf_dma_contig_user_get(struct videobuf_dma_contig_memory *mem,
 					struct videobuf_buffer *vb)
 {
+	unsigned long untagged_baddr = untagged_addr(vb->baddr);
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma;
 	unsigned long prev_pfn, this_pfn;
@@ -167,22 +168,22 @@ static int videobuf_dma_contig_user_get(struct videobuf_dma_contig_memory *mem,
 	unsigned int offset;
 	int ret;
 
-	offset = vb->baddr & ~PAGE_MASK;
+	offset = untagged_baddr & ~PAGE_MASK;
 	mem->size = PAGE_ALIGN(vb->size + offset);
 	ret = -EINVAL;
 
 	down_read(&mm->mmap_sem);
 
-	vma = find_vma(mm, vb->baddr);
+	vma = find_vma(mm, untagged_baddr);
 	if (!vma)
 		goto out_up;
 
-	if ((vb->baddr + mem->size) > vma->vm_end)
+	if ((untagged_baddr + mem->size) > vma->vm_end)
 		goto out_up;
 
 	pages_done = 0;
 	prev_pfn = 0; /* kill warning */
-	user_address = vb->baddr;
+	user_address = untagged_baddr;
 
 	while (pages_done < (mem->size >> PAGE_SHIFT)) {
 		ret = follow_pfn(vma, user_address, &this_pfn);
-- 
2.22.0.rc1.311.g5d7573a151-goog

[PATCH v16 14/16] tee, arm64: untag user pointers in tee_shm_register

[Andrey Konovalov]

This patch is a part of a series that extends arm64 kernel ABI to allow to
pass tagged user pointers (with the top byte set to something else other
than 0x00) as syscall arguments.

tee_shm_register()->optee_shm_unregister()->check_mem_type() uses provided
user pointers for vma lookups (via __check_mem_type()), which can only by
done with untagged pointers.

Untag user pointers in this function.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 drivers/tee/tee_shm.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
index 49fd7312e2aa..96945f4cefb8 100644
--- a/drivers/tee/tee_shm.c
+++ b/drivers/tee/tee_shm.c
@@ -263,6 +263,7 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
 	shm->teedev = teedev;
 	shm->ctx = ctx;
 	shm->id = -1;
+	addr = untagged_addr(addr);
 	start = rounddown(addr, PAGE_SIZE);
 	shm->offset = addr - start;
 	shm->size = length;
-- 
2.22.0.rc1.311.g5d7573a151-goog

[PATCH v16 15/16] vfio/type1, arm64: untag user pointers in vaddr_get_pfn

[Andrey Konovalov]

This patch is a part of a series that extends arm64 kernel ABI to allow to
pass tagged user pointers (with the top byte set to something else other
than 0x00) as syscall arguments.

vaddr_get_pfn() uses provided user pointers for vma lookups, which can
only by done with untagged pointers.

Untag user pointers in this function.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 drivers/vfio/vfio_iommu_type1.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 3ddc375e7063..528e39a1c2dd 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -384,6 +384,8 @@ static int vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr,
 
 	down_read(&mm->mmap_sem);
 
+	vaddr = untagged_addr(vaddr);
+
 	vma = find_vma_intersection(mm, vaddr, vaddr + 1);
 
 	if (vma && vma->vm_flags & VM_PFNMAP) {
-- 
2.22.0.rc1.311.g5d7573a151-goog

[PATCH v16 16/16] selftests, arm64: add a selftest for passing tagged pointers to kernel

[Andrey Konovalov]

This patch is a part of a series that extends arm64 kernel ABI to allow to
pass tagged user pointers (with the top byte set to something else other
than 0x00) as syscall arguments.

This patch adds a simple test, that calls the uname syscall with a
tagged user pointer as an argument. Without the kernel accepting tagged
user pointers the test fails with EFAULT.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 tools/testing/selftests/arm64/.gitignore      |  1 +
 tools/testing/selftests/arm64/Makefile        | 22 ++++++++++
 .../testing/selftests/arm64/run_tags_test.sh  | 12 ++++++
 tools/testing/selftests/arm64/tags_lib.c      | 42 +++++++++++++++++++
 tools/testing/selftests/arm64/tags_test.c     | 18 ++++++++
 5 files changed, 95 insertions(+)
 create mode 100644 tools/testing/selftests/arm64/.gitignore
 create mode 100644 tools/testing/selftests/arm64/Makefile
 create mode 100755 tools/testing/selftests/arm64/run_tags_test.sh
 create mode 100644 tools/testing/selftests/arm64/tags_lib.c
 create mode 100644 tools/testing/selftests/arm64/tags_test.c

diff --git a/tools/testing/selftests/arm64/.gitignore b/tools/testing/selftests/arm64/.gitignore
new file mode 100644
index 000000000000..e8fae8d61ed6
--- /dev/null
+++ b/tools/testing/selftests/arm64/.gitignore
@@ -0,0 +1 @@
+tags_test
diff --git a/tools/testing/selftests/arm64/Makefile b/tools/testing/selftests/arm64/Makefile
new file mode 100644
index 000000000000..9dee18727923
--- /dev/null
+++ b/tools/testing/selftests/arm64/Makefile
@@ -0,0 +1,22 @@
+# SPDX-License-Identifier: GPL-2.0
+
+include ../lib.mk
+
+# ARCH can be overridden by the user for cross compiling
+ARCH ?= $(shell uname -m 2>/dev/null || echo not)
+
+ifneq (,$(filter $(ARCH),aarch64 arm64))
+
+TEST_CUSTOM_PROGS := $(OUTPUT)/tags_test
+
+$(OUTPUT)/tags_test: tags_test.c $(OUTPUT)/tags_lib.so
+	$(CC) -o $@ $(CFLAGS) $(LDFLAGS) $<
+
+$(OUTPUT)/tags_lib.so: tags_lib.c
+	$(CC) -o $@ -shared $(CFLAGS) $(LDFLAGS) $^
+
+TEST_PROGS := run_tags_test.sh
+
+all: $(TEST_CUSTOM_PROGS)
+
+endif
diff --git a/tools/testing/selftests/arm64/run_tags_test.sh b/tools/testing/selftests/arm64/run_tags_test.sh
new file mode 100755
index 000000000000..2bbe0cd4220b
--- /dev/null
+++ b/tools/testing/selftests/arm64/run_tags_test.sh
@@ -0,0 +1,12 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+
+echo "--------------------"
+echo "running tags test"
+echo "--------------------"
+LD_PRELOAD=./tags_lib.so ./tags_test
+if [ $? -ne 0 ]; then
+	echo "[FAIL]"
+else
+	echo "[PASS]"
+fi
diff --git a/tools/testing/selftests/arm64/tags_lib.c b/tools/testing/selftests/arm64/tags_lib.c
new file mode 100644
index 000000000000..8a674509216e
--- /dev/null
+++ b/tools/testing/selftests/arm64/tags_lib.c
@@ -0,0 +1,42 @@
+#include <stdlib.h>
+
+#define TAG_SHIFT	(56)
+#define TAG_MASK	(0xffUL << TAG_SHIFT)
+
+void *__libc_malloc(size_t size);
+void __libc_free(void *ptr);
+void *__libc_realloc(void *ptr, size_t size);
+void *__libc_calloc(size_t nmemb, size_t size);
+
+static void *tag_ptr(void *ptr)
+{
+	unsigned long tag = rand() & 0xff;
+	if (!ptr)
+		return ptr;
+	return (void *)((unsigned long)ptr | (tag << TAG_SHIFT));
+}
+
+static void *untag_ptr(void *ptr)
+{
+	return (void *)((unsigned long)ptr & ~TAG_MASK);
+}
+
+void *malloc(size_t size)
+{
+	return tag_ptr(__libc_malloc(size));
+}
+
+void free(void *ptr)
+{
+	__libc_free(untag_ptr(ptr));
+}
+
+void *realloc(void *ptr, size_t size)
+{
+	return tag_ptr(__libc_realloc(untag_ptr(ptr), size));
+}
+
+void *calloc(size_t nmemb, size_t size)
+{
+	return tag_ptr(__libc_calloc(nmemb, size));
+}
diff --git a/tools/testing/selftests/arm64/tags_test.c b/tools/testing/selftests/arm64/tags_test.c
new file mode 100644
index 000000000000..263b302874ed
--- /dev/null
+++ b/tools/testing/selftests/arm64/tags_test.c
@@ -0,0 +1,18 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdint.h>
+#include <sys/utsname.h>
+
+int main(void)
+{
+	struct utsname *ptr;
+	int err;
+
+	ptr = (struct utsname *)malloc(sizeof(*ptr));
+	err = uname(ptr);
+	free(ptr);
+	return err;
+}
-- 
2.22.0.rc1.311.g5d7573a151-goog

Re: [PATCH v16 01/16] uaccess: add untagged_addr definition for other arches

[Khalid Aziz]

On 6/3/19 10:55 AM, Andrey Konovalov wrote:
> To allow arm64 syscalls to accept tagged pointers from userspace, we must
> untag them when they are passed to the kernel. Since untagging is done in
> generic parts of the kernel, the untagged_addr macro needs to be defined
> for all architectures.
> 
> Define it as a noop for architectures other than arm64.
> 
> Acked-by: Catalin Marinas <catalin.marinas@arm.com>
> Reviewed-by: Khalid Aziz <khalid.aziz@oracle.com>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> ---
>  include/linux/mm.h | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 0e8834ac32b7..949d43e9c0b6 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -99,6 +99,10 @@ extern int mmap_rnd_compat_bits __read_mostly;
>  #include <asm/pgtable.h>
>  #include <asm/processor.h>
>  
> +#ifndef untagged_addr
> +#define untagged_addr(addr) (addr)
> +#endif
> +
>  #ifndef __pa_symbol
>  #define __pa_symbol(x)  __pa(RELOC_HIDE((unsigned long)(x), 0))
>  #endif
> 

Andrey,

This patch has now become part of the other patch series Chris Hellwig
has sent out -
<https://lore.kernel.org/lkml/20190601074959.14036-1-hch@lst.de/>. Can
you coordinate with that patch series?

--
Khalid

Re: [PATCH v16 01/16] uaccess: add untagged_addr definition for other arches

[Andrey Konovalov]

On Mon, Jun 3, 2019 at 7:04 PM Khalid Aziz <khalid.aziz@oracle.com> wrote:
>
> On 6/3/19 10:55 AM, Andrey Konovalov wrote:
> > To allow arm64 syscalls to accept tagged pointers from userspace, we must
> > untag them when they are passed to the kernel. Since untagging is done in
> > generic parts of the kernel, the untagged_addr macro needs to be defined
> > for all architectures.
> >
> > Define it as a noop for architectures other than arm64.
> >
> > Acked-by: Catalin Marinas <catalin.marinas@arm.com>
> > Reviewed-by: Khalid Aziz <khalid.aziz@oracle.com>
> > Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> > ---
> >  include/linux/mm.h | 4 ++++
> >  1 file changed, 4 insertions(+)
> >
> > diff --git a/include/linux/mm.h b/include/linux/mm.h
> > index 0e8834ac32b7..949d43e9c0b6 100644
> > --- a/include/linux/mm.h
> > +++ b/include/linux/mm.h
> > @@ -99,6 +99,10 @@ extern int mmap_rnd_compat_bits __read_mostly;
> >  #include <asm/pgtable.h>
> >  #include <asm/processor.h>
> >
> > +#ifndef untagged_addr
> > +#define untagged_addr(addr) (addr)
> > +#endif
> > +
> >  #ifndef __pa_symbol
> >  #define __pa_symbol(x)  __pa(RELOC_HIDE((unsigned long)(x), 0))
> >  #endif
> >
>
> Andrey,
>
> This patch has now become part of the other patch series Chris Hellwig
> has sent out -
> <https://lore.kernel.org/lkml/20190601074959.14036-1-hch@lst.de/>. Can
> you coordinate with that patch series?

Hi!

Yes, I've seen it. How should I coordinate? Rebase this series on top
of that one?

Thanks!

>
> --
> Khalid
>

Re: [PATCH v16 01/16] uaccess: add untagged_addr definition for other arches

[Khalid Aziz]

On 6/3/19 11:06 AM, Andrey Konovalov wrote:
> On Mon, Jun 3, 2019 at 7:04 PM Khalid Aziz <khalid.aziz@oracle.com> wrote:
>> Andrey,
>>
>> This patch has now become part of the other patch series Chris Hellwig
>> has sent out -
>> <https://lore.kernel.org/lkml/20190601074959.14036-1-hch@lst.de/>. Can
>> you coordinate with that patch series?
> 
> Hi!
> 
> Yes, I've seen it. How should I coordinate? Rebase this series on top
> of that one?

That would be one way to do it. Better yet, separate this patch from
both patch series, make it standalone and then rebase the two patch
series on top of it.

--
Khalid

Re: [PATCH v16 01/16] uaccess: add untagged_addr definition for other arches

[Christoph Hellwig]

On Mon, Jun 03, 2019 at 11:24:35AM -0600, Khalid Aziz wrote:
> On 6/3/19 11:06 AM, Andrey Konovalov wrote:
> > On Mon, Jun 3, 2019 at 7:04 PM Khalid Aziz <khalid.aziz@oracle.com> wrote:
> >> Andrey,
> >>
> >> This patch has now become part of the other patch series Chris Hellwig
> >> has sent out -
> >> <https://lore.kernel.org/lkml/20190601074959.14036-1-hch@lst.de/>. Can
> >> you coordinate with that patch series?
> > 
> > Hi!
> > 
> > Yes, I've seen it. How should I coordinate? Rebase this series on top
> > of that one?
> 
> That would be one way to do it. Better yet, separate this patch from
> both patch series, make it standalone and then rebase the two patch
> series on top of it.

I think easiest would be to just ask Linus if he could make an exception
and include this trivial prep patch in 5.2-rc.

Re: [PATCH v16 12/16] IB, arm64: untag user pointers in ib_uverbs_(re)reg_mr()

[Jason Gunthorpe]

On Mon, Jun 03, 2019 at 06:55:14PM +0200, Andrey Konovalov wrote:
> This patch is a part of a series that extends arm64 kernel ABI to allow to
> pass tagged user pointers (with the top byte set to something else other
> than 0x00) as syscall arguments.
> 
> ib_uverbs_(re)reg_mr() use provided user pointers for vma lookups (through
> e.g. mlx4_get_umem_mr()), which can only by done with untagged pointers.
> 
> Untag user pointers in these functions.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
>  drivers/infiniband/core/uverbs_cmd.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c
> index 5a3a1780ceea..f88ee733e617 100644
> +++ b/drivers/infiniband/core/uverbs_cmd.c
> @@ -709,6 +709,8 @@ static int ib_uverbs_reg_mr(struct uverbs_attr_bundle *attrs)
>  	if (ret)
>  		return ret;
>  
> +	cmd.start = untagged_addr(cmd.start);
> +
>  	if ((cmd.start & ~PAGE_MASK) != (cmd.hca_va & ~PAGE_MASK))
>  		return -EINVAL;

I feel like we shouldn't thave to do this here, surely the cmd.start
should flow unmodified to get_user_pages, and gup should untag it?

ie, this sort of direction for the IB code (this would be a giant
patch, so I didn't have time to write it all, but I think it is much
saner):

diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
index 54628ef879f0ce..7b3b736c87c253 100644
--- a/drivers/infiniband/core/umem.c
+++ b/drivers/infiniband/core/umem.c
@@ -193,7 +193,7 @@ EXPORT_SYMBOL(ib_umem_find_best_pgsz);
  * @access: IB_ACCESS_xxx flags for memory being pinned
  * @dmasync: flush in-flight DMA when the memory region is written
  */
-struct ib_umem *ib_umem_get(struct ib_udata *udata, unsigned long addr,
+struct ib_umem *ib_umem_get(struct ib_udata *udata, void __user *addr,
 			    size_t size, int access, int dmasync)
 {
 	struct ib_ucontext *context;
@@ -201,7 +201,7 @@ struct ib_umem *ib_umem_get(struct ib_udata *udata, unsigned long addr,
 	struct page **page_list;
 	unsigned long lock_limit;
 	unsigned long new_pinned;
-	unsigned long cur_base;
+	void __user *cur_base;
 	struct mm_struct *mm;
 	unsigned long npages;
 	int ret;
diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c
index 5a3a1780ceea4d..94389e7f12371f 100644
--- a/drivers/infiniband/core/uverbs_cmd.c
+++ b/drivers/infiniband/core/uverbs_cmd.c
@@ -735,7 +735,8 @@ static int ib_uverbs_reg_mr(struct uverbs_attr_bundle *attrs)
 		}
 	}
 
-	mr = pd->device->ops.reg_user_mr(pd, cmd.start, cmd.length, cmd.hca_va,
+	mr = pd->device->ops.reg_user_mr(pd, u64_to_user_ptr(cmd.start),
+					 cmd.length, cmd.hca_va,
 					 cmd.access_flags,
 					 &attrs->driver_udata);
 	if (IS_ERR(mr)) {
diff --git a/drivers/infiniband/hw/mlx5/mr.c b/drivers/infiniband/hw/mlx5/mr.c
index 4d033796dcfcc2..bddbb952082fc5 100644
--- a/drivers/infiniband/hw/mlx5/mr.c
+++ b/drivers/infiniband/hw/mlx5/mr.c
@@ -786,7 +786,7 @@ static int mr_cache_max_order(struct mlx5_ib_dev *dev)
 }
 
 static int mr_umem_get(struct mlx5_ib_dev *dev, struct ib_udata *udata,
-		       u64 start, u64 length, int access_flags,
+		       void __user *start, u64 length, int access_flags,
 		       struct ib_umem **umem, int *npages, int *page_shift,
 		       int *ncont, int *order)
 {
@@ -1262,8 +1262,8 @@ struct ib_mr *mlx5_ib_reg_dm_mr(struct ib_pd *pd, struct ib_dm *dm,
 				 attr->access_flags, mode);
 }
 
-struct ib_mr *mlx5_ib_reg_user_mr(struct ib_pd *pd, u64 start, u64 length,
-				  u64 virt_addr, int access_flags,
+struct ib_mr *mlx5_ib_reg_user_mr(struct ib_pd *pd, void __user *start,
+				  u64 length, u64 virt_addr, int access_flags,
 				  struct ib_udata *udata)
 {
 	struct mlx5_ib_dev *dev = to_mdev(pd->device);
diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
index ec6446864b08e9..b3c8eaaa35c760 100644
--- a/include/rdma/ib_verbs.h
+++ b/include/rdma/ib_verbs.h
@@ -2464,8 +2464,8 @@ struct ib_device_ops {
 	struct ib_mr *(*reg_user_mr)(struct ib_pd *pd, u64 start, u64 length,
 				     u64 virt_addr, int mr_access_flags,
 				     struct ib_udata *udata);
-	int (*rereg_user_mr)(struct ib_mr *mr, int flags, u64 start, u64 length,
-			     u64 virt_addr, int mr_access_flags,
+	int (*rereg_user_mr)(struct ib_mr *mr, int flags, void __user *start,
+			     u64 length, u64 virt_addr, int mr_access_flags,
 			     struct ib_pd *pd, struct ib_udata *udata);
 	int (*dereg_mr)(struct ib_mr *mr, struct ib_udata *udata);
 	struct ib_mr *(*alloc_mr)(struct ib_pd *pd, enum ib_mr_type mr_type,

Re: [PATCH v16 01/16] uaccess: add untagged_addr definition for other arches

[Khalid Aziz]

On 6/3/19 11:29 AM, Christoph Hellwig wrote:
> On Mon, Jun 03, 2019 at 11:24:35AM -0600, Khalid Aziz wrote:
>> On 6/3/19 11:06 AM, Andrey Konovalov wrote:
>>> On Mon, Jun 3, 2019 at 7:04 PM Khalid Aziz <khalid.aziz@oracle.com> wrote:
>>>> Andrey,
>>>>
>>>> This patch has now become part of the other patch series Chris Hellwig
>>>> has sent out -
>>>> <https://lore.kernel.org/lkml/20190601074959.14036-1-hch@lst.de/>. Can
>>>> you coordinate with that patch series?
>>>
>>> Hi!
>>>
>>> Yes, I've seen it. How should I coordinate? Rebase this series on top
>>> of that one?
>>
>> That would be one way to do it. Better yet, separate this patch from
>> both patch series, make it standalone and then rebase the two patch
>> series on top of it.
> 
> I think easiest would be to just ask Linus if he could make an exception
> and include this trivial prep patch in 5.2-rc.
> 

Andrey,

Would you mind updating the commit log to make it not arm64 specific and
sending this patch out by itself. We can then ask Linus if he can
include just this patch in the next rc.

Thanks,
Khalid

Re: [PATCH v16 01/16] uaccess: add untagged_addr definition for other arches

[Andrey Konovalov]

On Mon, Jun 3, 2019 at 8:17 PM Khalid Aziz <khalid.aziz@oracle.com> wrote:
>
> On 6/3/19 11:29 AM, Christoph Hellwig wrote:
> > On Mon, Jun 03, 2019 at 11:24:35AM -0600, Khalid Aziz wrote:
> >> On 6/3/19 11:06 AM, Andrey Konovalov wrote:
> >>> On Mon, Jun 3, 2019 at 7:04 PM Khalid Aziz <khalid.aziz@oracle.com> wrote:
> >>>> Andrey,
> >>>>
> >>>> This patch has now become part of the other patch series Chris Hellwig
> >>>> has sent out -
> >>>> <https://lore.kernel.org/lkml/20190601074959.14036-1-hch@lst.de/>. Can
> >>>> you coordinate with that patch series?
> >>>
> >>> Hi!
> >>>
> >>> Yes, I've seen it. How should I coordinate? Rebase this series on top
> >>> of that one?
> >>
> >> That would be one way to do it. Better yet, separate this patch from
> >> both patch series, make it standalone and then rebase the two patch
> >> series on top of it.
> >
> > I think easiest would be to just ask Linus if he could make an exception
> > and include this trivial prep patch in 5.2-rc.
> >
>
> Andrey,
>
> Would you mind updating the commit log to make it not arm64 specific and
> sending this patch out by itself. We can then ask Linus if he can
> include just this patch in the next rc.

Sure! Just sent it out.

>
> Thanks,
> Khalid
>

Re: [PATCH v16 12/16] IB, arm64: untag user pointers in ib_uverbs_(re)reg_mr()

[Andrey Konovalov]

On Mon, Jun 3, 2019 at 7:46 PM Jason Gunthorpe <jgg@ziepe.ca> wrote:
>
> On Mon, Jun 03, 2019 at 06:55:14PM +0200, Andrey Konovalov wrote:
> > This patch is a part of a series that extends arm64 kernel ABI to allow to
> > pass tagged user pointers (with the top byte set to something else other
> > than 0x00) as syscall arguments.
> >
> > ib_uverbs_(re)reg_mr() use provided user pointers for vma lookups (through
> > e.g. mlx4_get_umem_mr()), which can only by done with untagged pointers.
> >
> > Untag user pointers in these functions.
> >
> > Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> >  drivers/infiniband/core/uverbs_cmd.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> >
> > diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c
> > index 5a3a1780ceea..f88ee733e617 100644
> > +++ b/drivers/infiniband/core/uverbs_cmd.c
> > @@ -709,6 +709,8 @@ static int ib_uverbs_reg_mr(struct uverbs_attr_bundle *attrs)
> >       if (ret)
> >               return ret;
> >
> > +     cmd.start = untagged_addr(cmd.start);
> > +
> >       if ((cmd.start & ~PAGE_MASK) != (cmd.hca_va & ~PAGE_MASK))
> >               return -EINVAL;
>
> I feel like we shouldn't thave to do this here, surely the cmd.start
> should flow unmodified to get_user_pages, and gup should untag it?
>
> ie, this sort of direction for the IB code (this would be a giant
> patch, so I didn't have time to write it all, but I think it is much
> saner):

Hi Jason,

ib_uverbs_reg_mr() passes cmd.start to mlx4_get_umem_mr(), which calls
find_vma(), which only accepts untagged addresses. Could you explain
how your patch helps?

Thanks!

>
> diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
> index 54628ef879f0ce..7b3b736c87c253 100644
> --- a/drivers/infiniband/core/umem.c
> +++ b/drivers/infiniband/core/umem.c
> @@ -193,7 +193,7 @@ EXPORT_SYMBOL(ib_umem_find_best_pgsz);
>   * @access: IB_ACCESS_xxx flags for memory being pinned
>   * @dmasync: flush in-flight DMA when the memory region is written
>   */
> -struct ib_umem *ib_umem_get(struct ib_udata *udata, unsigned long addr,
> +struct ib_umem *ib_umem_get(struct ib_udata *udata, void __user *addr,
>                             size_t size, int access, int dmasync)
>  {
>         struct ib_ucontext *context;
> @@ -201,7 +201,7 @@ struct ib_umem *ib_umem_get(struct ib_udata *udata, unsigned long addr,
>         struct page **page_list;
>         unsigned long lock_limit;
>         unsigned long new_pinned;
> -       unsigned long cur_base;
> +       void __user *cur_base;
>         struct mm_struct *mm;
>         unsigned long npages;
>         int ret;
> diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c
> index 5a3a1780ceea4d..94389e7f12371f 100644
> --- a/drivers/infiniband/core/uverbs_cmd.c
> +++ b/drivers/infiniband/core/uverbs_cmd.c
> @@ -735,7 +735,8 @@ static int ib_uverbs_reg_mr(struct uverbs_attr_bundle *attrs)
>                 }
>         }
>
> -       mr = pd->device->ops.reg_user_mr(pd, cmd.start, cmd.length, cmd.hca_va,
> +       mr = pd->device->ops.reg_user_mr(pd, u64_to_user_ptr(cmd.start),
> +                                        cmd.length, cmd.hca_va,
>                                          cmd.access_flags,
>                                          &attrs->driver_udata);
>         if (IS_ERR(mr)) {
> diff --git a/drivers/infiniband/hw/mlx5/mr.c b/drivers/infiniband/hw/mlx5/mr.c
> index 4d033796dcfcc2..bddbb952082fc5 100644
> --- a/drivers/infiniband/hw/mlx5/mr.c
> +++ b/drivers/infiniband/hw/mlx5/mr.c
> @@ -786,7 +786,7 @@ static int mr_cache_max_order(struct mlx5_ib_dev *dev)
>  }
>
>  static int mr_umem_get(struct mlx5_ib_dev *dev, struct ib_udata *udata,
> -                      u64 start, u64 length, int access_flags,
> +                      void __user *start, u64 length, int access_flags,
>                        struct ib_umem **umem, int *npages, int *page_shift,
>                        int *ncont, int *order)
>  {
> @@ -1262,8 +1262,8 @@ struct ib_mr *mlx5_ib_reg_dm_mr(struct ib_pd *pd, struct ib_dm *dm,
>                                  attr->access_flags, mode);
>  }
>
> -struct ib_mr *mlx5_ib_reg_user_mr(struct ib_pd *pd, u64 start, u64 length,
> -                                 u64 virt_addr, int access_flags,
> +struct ib_mr *mlx5_ib_reg_user_mr(struct ib_pd *pd, void __user *start,
> +                                 u64 length, u64 virt_addr, int access_flags,
>                                   struct ib_udata *udata)
>  {
>         struct mlx5_ib_dev *dev = to_mdev(pd->device);
> diff --git a/include/rdma/ib_verbs.h b/include/rdma/ib_verbs.h
> index ec6446864b08e9..b3c8eaaa35c760 100644
> --- a/include/rdma/ib_verbs.h
> +++ b/include/rdma/ib_verbs.h
> @@ -2464,8 +2464,8 @@ struct ib_device_ops {
>         struct ib_mr *(*reg_user_mr)(struct ib_pd *pd, u64 start, u64 length,
>                                      u64 virt_addr, int mr_access_flags,
>                                      struct ib_udata *udata);
> -       int (*rereg_user_mr)(struct ib_mr *mr, int flags, u64 start, u64 length,
> -                            u64 virt_addr, int mr_access_flags,
> +       int (*rereg_user_mr)(struct ib_mr *mr, int flags, void __user *start,
> +                            u64 length, u64 virt_addr, int mr_access_flags,
>                              struct ib_pd *pd, struct ib_udata *udata);
>         int (*dereg_mr)(struct ib_mr *mr, struct ib_udata *udata);
>         struct ib_mr *(*alloc_mr)(struct ib_pd *pd, enum ib_mr_type mr_type,

Re: [PATCH v16 12/16] IB, arm64: untag user pointers in ib_uverbs_(re)reg_mr()

[Jason Gunthorpe]

On Tue, Jun 04, 2019 at 02:18:19PM +0200, Andrey Konovalov wrote:
> On Mon, Jun 3, 2019 at 7:46 PM Jason Gunthorpe <jgg@ziepe.ca> wrote:
> >
> > On Mon, Jun 03, 2019 at 06:55:14PM +0200, Andrey Konovalov wrote:
> > > This patch is a part of a series that extends arm64 kernel ABI to allow to
> > > pass tagged user pointers (with the top byte set to something else other
> > > than 0x00) as syscall arguments.
> > >
> > > ib_uverbs_(re)reg_mr() use provided user pointers for vma lookups (through
> > > e.g. mlx4_get_umem_mr()), which can only by done with untagged pointers.
> > >
> > > Untag user pointers in these functions.
> > >
> > > Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> > >  drivers/infiniband/core/uverbs_cmd.c | 4 ++++
> > >  1 file changed, 4 insertions(+)
> > >
> > > diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c
> > > index 5a3a1780ceea..f88ee733e617 100644
> > > +++ b/drivers/infiniband/core/uverbs_cmd.c
> > > @@ -709,6 +709,8 @@ static int ib_uverbs_reg_mr(struct uverbs_attr_bundle *attrs)
> > >       if (ret)
> > >               return ret;
> > >
> > > +     cmd.start = untagged_addr(cmd.start);
> > > +
> > >       if ((cmd.start & ~PAGE_MASK) != (cmd.hca_va & ~PAGE_MASK))
> > >               return -EINVAL;
> >
> > I feel like we shouldn't thave to do this here, surely the cmd.start
> > should flow unmodified to get_user_pages, and gup should untag it?
> >
> > ie, this sort of direction for the IB code (this would be a giant
> > patch, so I didn't have time to write it all, but I think it is much
> > saner):
> 
> Hi Jason,
> 
> ib_uverbs_reg_mr() passes cmd.start to mlx4_get_umem_mr(), which calls
> find_vma(), which only accepts untagged addresses. Could you explain
> how your patch helps?

That mlx4 is just a 'weird duck', it is not the normal flow, and I
don't think the core code should be making special consideration for
it.

Jason

Re: [PATCH v16 12/16] IB, arm64: untag user pointers in ib_uverbs_(re)reg_mr()

[Andrey Konovalov]

On Tue, Jun 4, 2019 at 2:27 PM Jason Gunthorpe <jgg@ziepe.ca> wrote:
>
> On Tue, Jun 04, 2019 at 02:18:19PM +0200, Andrey Konovalov wrote:
> > On Mon, Jun 3, 2019 at 7:46 PM Jason Gunthorpe <jgg@ziepe.ca> wrote:
> > >
> > > On Mon, Jun 03, 2019 at 06:55:14PM +0200, Andrey Konovalov wrote:
> > > > This patch is a part of a series that extends arm64 kernel ABI to allow to
> > > > pass tagged user pointers (with the top byte set to something else other
> > > > than 0x00) as syscall arguments.
> > > >
> > > > ib_uverbs_(re)reg_mr() use provided user pointers for vma lookups (through
> > > > e.g. mlx4_get_umem_mr()), which can only by done with untagged pointers.
> > > >
> > > > Untag user pointers in these functions.
> > > >
> > > > Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> > > >  drivers/infiniband/core/uverbs_cmd.c | 4 ++++
> > > >  1 file changed, 4 insertions(+)
> > > >
> > > > diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c
> > > > index 5a3a1780ceea..f88ee733e617 100644
> > > > +++ b/drivers/infiniband/core/uverbs_cmd.c
> > > > @@ -709,6 +709,8 @@ static int ib_uverbs_reg_mr(struct uverbs_attr_bundle *attrs)
> > > >       if (ret)
> > > >               return ret;
> > > >
> > > > +     cmd.start = untagged_addr(cmd.start);
> > > > +
> > > >       if ((cmd.start & ~PAGE_MASK) != (cmd.hca_va & ~PAGE_MASK))
> > > >               return -EINVAL;
> > >
> > > I feel like we shouldn't thave to do this here, surely the cmd.start
> > > should flow unmodified to get_user_pages, and gup should untag it?
> > >
> > > ie, this sort of direction for the IB code (this would be a giant
> > > patch, so I didn't have time to write it all, but I think it is much
> > > saner):
> >
> > Hi Jason,
> >
> > ib_uverbs_reg_mr() passes cmd.start to mlx4_get_umem_mr(), which calls
> > find_vma(), which only accepts untagged addresses. Could you explain
> > how your patch helps?
>
> That mlx4 is just a 'weird duck', it is not the normal flow, and I
> don't think the core code should be making special consideration for
> it.

How do you think we should do untagging (or something else) to deal
with this 'weird duck' case?

>
> Jason

Re: [PATCH v16 12/16] IB, arm64: untag user pointers in ib_uverbs_(re)reg_mr()

[Jason Gunthorpe]

On Tue, Jun 04, 2019 at 02:45:32PM +0200, Andrey Konovalov wrote:
> On Tue, Jun 4, 2019 at 2:27 PM Jason Gunthorpe <jgg@ziepe.ca> wrote:
> >
> > On Tue, Jun 04, 2019 at 02:18:19PM +0200, Andrey Konovalov wrote:
> > > On Mon, Jun 3, 2019 at 7:46 PM Jason Gunthorpe <jgg@ziepe.ca> wrote:
> > > >
> > > > On Mon, Jun 03, 2019 at 06:55:14PM +0200, Andrey Konovalov wrote:
> > > > > This patch is a part of a series that extends arm64 kernel ABI to allow to
> > > > > pass tagged user pointers (with the top byte set to something else other
> > > > > than 0x00) as syscall arguments.
> > > > >
> > > > > ib_uverbs_(re)reg_mr() use provided user pointers for vma lookups (through
> > > > > e.g. mlx4_get_umem_mr()), which can only by done with untagged pointers.
> > > > >
> > > > > Untag user pointers in these functions.
> > > > >
> > > > > Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> > > > >  drivers/infiniband/core/uverbs_cmd.c | 4 ++++
> > > > >  1 file changed, 4 insertions(+)
> > > > >
> > > > > diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c
> > > > > index 5a3a1780ceea..f88ee733e617 100644
> > > > > +++ b/drivers/infiniband/core/uverbs_cmd.c
> > > > > @@ -709,6 +709,8 @@ static int ib_uverbs_reg_mr(struct uverbs_attr_bundle *attrs)
> > > > >       if (ret)
> > > > >               return ret;
> > > > >
> > > > > +     cmd.start = untagged_addr(cmd.start);
> > > > > +
> > > > >       if ((cmd.start & ~PAGE_MASK) != (cmd.hca_va & ~PAGE_MASK))
> > > > >               return -EINVAL;
> > > >
> > > > I feel like we shouldn't thave to do this here, surely the cmd.start
> > > > should flow unmodified to get_user_pages, and gup should untag it?
> > > >
> > > > ie, this sort of direction for the IB code (this would be a giant
> > > > patch, so I didn't have time to write it all, but I think it is much
> > > > saner):
> > >
> > > Hi Jason,
> > >
> > > ib_uverbs_reg_mr() passes cmd.start to mlx4_get_umem_mr(), which calls
> > > find_vma(), which only accepts untagged addresses. Could you explain
> > > how your patch helps?
> >
> > That mlx4 is just a 'weird duck', it is not the normal flow, and I
> > don't think the core code should be making special consideration for
> > it.
> 
> How do you think we should do untagging (or something else) to deal
> with this 'weird duck' case?

mlx4 should handle it around the call to find_vma like other patches
do, ideally as part of the cast from a void __user * to the unsigned
long that find_vma needs

Jason

Re: [PATCH v16 12/16] IB, arm64: untag user pointers in ib_uverbs_(re)reg_mr()

[Andrey Konovalov]

On Tue, Jun 4, 2019 at 3:02 PM Jason Gunthorpe <jgg@ziepe.ca> wrote:
>
> On Tue, Jun 04, 2019 at 02:45:32PM +0200, Andrey Konovalov wrote:
> > On Tue, Jun 4, 2019 at 2:27 PM Jason Gunthorpe <jgg@ziepe.ca> wrote:
> > >
> > > On Tue, Jun 04, 2019 at 02:18:19PM +0200, Andrey Konovalov wrote:
> > > > On Mon, Jun 3, 2019 at 7:46 PM Jason Gunthorpe <jgg@ziepe.ca> wrote:
> > > > >
> > > > > On Mon, Jun 03, 2019 at 06:55:14PM +0200, Andrey Konovalov wrote:
> > > > > > This patch is a part of a series that extends arm64 kernel ABI to allow to
> > > > > > pass tagged user pointers (with the top byte set to something else other
> > > > > > than 0x00) as syscall arguments.
> > > > > >
> > > > > > ib_uverbs_(re)reg_mr() use provided user pointers for vma lookups (through
> > > > > > e.g. mlx4_get_umem_mr()), which can only by done with untagged pointers.
> > > > > >
> > > > > > Untag user pointers in these functions.
> > > > > >
> > > > > > Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> > > > > >  drivers/infiniband/core/uverbs_cmd.c | 4 ++++
> > > > > >  1 file changed, 4 insertions(+)
> > > > > >
> > > > > > diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c
> > > > > > index 5a3a1780ceea..f88ee733e617 100644
> > > > > > +++ b/drivers/infiniband/core/uverbs_cmd.c
> > > > > > @@ -709,6 +709,8 @@ static int ib_uverbs_reg_mr(struct uverbs_attr_bundle *attrs)
> > > > > >       if (ret)
> > > > > >               return ret;
> > > > > >
> > > > > > +     cmd.start = untagged_addr(cmd.start);
> > > > > > +
> > > > > >       if ((cmd.start & ~PAGE_MASK) != (cmd.hca_va & ~PAGE_MASK))
> > > > > >               return -EINVAL;
> > > > >
> > > > > I feel like we shouldn't thave to do this here, surely the cmd.start
> > > > > should flow unmodified to get_user_pages, and gup should untag it?
> > > > >
> > > > > ie, this sort of direction for the IB code (this would be a giant
> > > > > patch, so I didn't have time to write it all, but I think it is much
> > > > > saner):
> > > >
> > > > Hi Jason,
> > > >
> > > > ib_uverbs_reg_mr() passes cmd.start to mlx4_get_umem_mr(), which calls
> > > > find_vma(), which only accepts untagged addresses. Could you explain
> > > > how your patch helps?
> > >
> > > That mlx4 is just a 'weird duck', it is not the normal flow, and I
> > > don't think the core code should be making special consideration for
> > > it.
> >
> > How do you think we should do untagging (or something else) to deal
> > with this 'weird duck' case?
>
> mlx4 should handle it around the call to find_vma like other patches
> do, ideally as part of the cast from a void __user * to the unsigned
> long that find_vma needs

So essentially what we had a few versions ago
(https://lkml.org/lkml/2019/4/30/785) plus changing unsigned longs to
__user * across all IB code? I think the second part is something
that's not related to this series and needs to be done separately. I
can move untagging back to mlx4_get_umem_mr() though.

Catalin, you've initially asked to to move untagging out of
mlx4_get_umem_mr(), do you have any comments on this?

>
> Jason

Re: [PATCH v16 14/16] tee, arm64: untag user pointers in tee_shm_register

[Jens Wiklander]

On Mon, Jun 3, 2019 at 6:56 PM Andrey Konovalov <andreyknvl@google.com> wrote:
>
> This patch is a part of a series that extends arm64 kernel ABI to allow to
> pass tagged user pointers (with the top byte set to something else other
> than 0x00) as syscall arguments.
>
> tee_shm_register()->optee_shm_unregister()->check_mem_type() uses provided
> user pointers for vma lookups (via __check_mem_type()), which can only by
> done with untagged pointers.
>
> Untag user pointers in this function.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

Acked-by: Jens Wiklander <jens.wiklander@linaro.org>

> ---
>  drivers/tee/tee_shm.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
> index 49fd7312e2aa..96945f4cefb8 100644
> --- a/drivers/tee/tee_shm.c
> +++ b/drivers/tee/tee_shm.c
> @@ -263,6 +263,7 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
>         shm->teedev = teedev;
>         shm->ctx = ctx;
>         shm->id = -1;
> +       addr = untagged_addr(addr);
>         start = rounddown(addr, PAGE_SIZE);
>         shm->offset = addr - start;
>         shm->size = length;
> --
> 2.22.0.rc1.311.g5d7573a151-goog
>

Re: [PATCH v16 03/16] lib, arm64: untag user pointers in strn*_user

[Kees Cook]

On Mon, Jun 03, 2019 at 06:55:05PM +0200, Andrey Konovalov wrote:
> This patch is a part of a series that extends arm64 kernel ABI to allow to
> pass tagged user pointers (with the top byte set to something else other
> than 0x00) as syscall arguments.
> 
> strncpy_from_user and strnlen_user accept user addresses as arguments, and
> do not go through the same path as copy_from_user and others, so here we
> need to handle the case of tagged user addresses separately.
> 
> Untag user pointers passed to these functions.
> 
> Note, that this patch only temporarily untags the pointers to perform
> validity checks, but then uses them as is to perform user memory accesses.
> 
> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

Acked-by: Kees Cook <keescook@chromium.org>

-Kees

> ---
>  lib/strncpy_from_user.c | 3 ++-
>  lib/strnlen_user.c      | 3 ++-
>  2 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/strncpy_from_user.c b/lib/strncpy_from_user.c
> index 023ba9f3b99f..dccb95af6003 100644
> --- a/lib/strncpy_from_user.c
> +++ b/lib/strncpy_from_user.c
> @@ -6,6 +6,7 @@
>  #include <linux/uaccess.h>
>  #include <linux/kernel.h>
>  #include <linux/errno.h>
> +#include <linux/mm.h>
>  
>  #include <asm/byteorder.h>
>  #include <asm/word-at-a-time.h>
> @@ -108,7 +109,7 @@ long strncpy_from_user(char *dst, const char __user *src, long count)
>  		return 0;
>  
>  	max_addr = user_addr_max();
> -	src_addr = (unsigned long)src;
> +	src_addr = (unsigned long)untagged_addr(src);
>  	if (likely(src_addr < max_addr)) {
>  		unsigned long max = max_addr - src_addr;
>  		long retval;
> diff --git a/lib/strnlen_user.c b/lib/strnlen_user.c
> index 7f2db3fe311f..28ff554a1be8 100644
> --- a/lib/strnlen_user.c
> +++ b/lib/strnlen_user.c
> @@ -2,6 +2,7 @@
>  #include <linux/kernel.h>
>  #include <linux/export.h>
>  #include <linux/uaccess.h>
> +#include <linux/mm.h>
>  
>  #include <asm/word-at-a-time.h>
>  
> @@ -109,7 +110,7 @@ long strnlen_user(const char __user *str, long count)
>  		return 0;
>  
>  	max_addr = user_addr_max();
> -	src_addr = (unsigned long)str;
> +	src_addr = (unsigned long)untagged_addr(str);
>  	if (likely(src_addr < max_addr)) {
>  		unsigned long max = max_addr - src_addr;
>  		long retval;
> -- 
> 2.22.0.rc1.311.g5d7573a151-goog
> 

-- 
Kees Cook

Re: [PATCH v16 04/16] mm: untag user pointers in do_pages_move

[Kees Cook]

On Mon, Jun 03, 2019 at 06:55:06PM +0200, Andrey Konovalov wrote:
> This patch is a part of a series that extends arm64 kernel ABI to allow to
> pass tagged user pointers (with the top byte set to something else other
> than 0x00) as syscall arguments.
> 
> do_pages_move() is used in the implementation of the move_pages syscall.
> 
> Untag user pointers in this function.
> 
> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

> ---
>  mm/migrate.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/mm/migrate.c b/mm/migrate.c
> index f2ecc2855a12..3930bb6fa656 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1617,6 +1617,7 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
>  		if (get_user(node, nodes + i))
>  			goto out_flush;
>  		addr = (unsigned long)p;
> +		addr = untagged_addr(addr);
>  
>  		err = -ENODEV;
>  		if (node < 0 || node >= MAX_NUMNODES)
> -- 
> 2.22.0.rc1.311.g5d7573a151-goog
> 

-- 
Kees Cook

Re: [PATCH v16 02/16] arm64: untag user pointers in access_ok and __uaccess_mask_ptr

[Kees Cook]

On Mon, Jun 03, 2019 at 06:55:04PM +0200, Andrey Konovalov wrote:
> This patch is a part of a series that extends arm64 kernel ABI to allow to
> pass tagged user pointers (with the top byte set to something else other
> than 0x00) as syscall arguments.
> 
> copy_from_user (and a few other similar functions) are used to copy data
> from user memory into the kernel memory or vice versa. Since a user can
> provided a tagged pointer to one of the syscalls that use copy_from_user,
> we need to correctly handle such pointers.
> 
> Do this by untagging user pointers in access_ok and in __uaccess_mask_ptr,
> before performing access validity checks.
> 
> Note, that this patch only temporarily untags the pointers to perform the
> checks, but then passes them as is into the kernel internals.
> 
> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

> ---
>  arch/arm64/include/asm/uaccess.h | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
> index e5d5f31c6d36..9164ecb5feca 100644
> --- a/arch/arm64/include/asm/uaccess.h
> +++ b/arch/arm64/include/asm/uaccess.h
> @@ -94,7 +94,7 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si
>  	return ret;
>  }
>  
> -#define access_ok(addr, size)	__range_ok(addr, size)
> +#define access_ok(addr, size)	__range_ok(untagged_addr(addr), size)
>  #define user_addr_max			get_fs
>  
>  #define _ASM_EXTABLE(from, to)						\
> @@ -226,7 +226,8 @@ static inline void uaccess_enable_not_uao(void)
>  
>  /*
>   * Sanitise a uaccess pointer such that it becomes NULL if above the
> - * current addr_limit.
> + * current addr_limit. In case the pointer is tagged (has the top byte set),
> + * untag the pointer before checking.
>   */
>  #define uaccess_mask_ptr(ptr) (__typeof__(ptr))__uaccess_mask_ptr(ptr)
>  static inline void __user *__uaccess_mask_ptr(const void __user *ptr)
> @@ -234,10 +235,11 @@ static inline void __user *__uaccess_mask_ptr(const void __user *ptr)
>  	void __user *safe_ptr;
>  
>  	asm volatile(
> -	"	bics	xzr, %1, %2\n"
> +	"	bics	xzr, %3, %2\n"
>  	"	csel	%0, %1, xzr, eq\n"
>  	: "=&r" (safe_ptr)
> -	: "r" (ptr), "r" (current_thread_info()->addr_limit)
> +	: "r" (ptr), "r" (current_thread_info()->addr_limit),
> +	  "r" (untagged_addr(ptr))
>  	: "cc");
>  
>  	csdb();
> -- 
> 2.22.0.rc1.311.g5d7573a151-goog
> 

-- 
Kees Cook

Re: [PATCH v16 05/16] arm64: untag user pointers passed to memory syscalls

[Kees Cook]

On Mon, Jun 03, 2019 at 06:55:07PM +0200, Andrey Konovalov wrote:
> This patch is a part of a series that extends arm64 kernel ABI to allow to
> pass tagged user pointers (with the top byte set to something else other
> than 0x00) as syscall arguments.
> 
> This patch allows tagged pointers to be passed to the following memory
> syscalls: get_mempolicy, madvise, mbind, mincore, mlock, mlock2, mprotect,
> mremap, msync, munlock.
> 
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

> ---
>  mm/madvise.c   | 2 ++
>  mm/mempolicy.c | 3 +++
>  mm/mincore.c   | 2 ++
>  mm/mlock.c     | 4 ++++
>  mm/mprotect.c  | 2 ++
>  mm/mremap.c    | 2 ++
>  mm/msync.c     | 2 ++
>  7 files changed, 17 insertions(+)
> 
> diff --git a/mm/madvise.c b/mm/madvise.c
> index 628022e674a7..39b82f8a698f 100644
> --- a/mm/madvise.c
> +++ b/mm/madvise.c
> @@ -810,6 +810,8 @@ SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
>  	size_t len;
>  	struct blk_plug plug;
>  
> +	start = untagged_addr(start);
> +
>  	if (!madvise_behavior_valid(behavior))
>  		return error;
>  
> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index 01600d80ae01..78e0a88b2680 100644
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -1360,6 +1360,7 @@ static long kernel_mbind(unsigned long start, unsigned long len,
>  	int err;
>  	unsigned short mode_flags;
>  
> +	start = untagged_addr(start);
>  	mode_flags = mode & MPOL_MODE_FLAGS;
>  	mode &= ~MPOL_MODE_FLAGS;
>  	if (mode >= MPOL_MAX)
> @@ -1517,6 +1518,8 @@ static int kernel_get_mempolicy(int __user *policy,
>  	int uninitialized_var(pval);
>  	nodemask_t nodes;
>  
> +	addr = untagged_addr(addr);
> +
>  	if (nmask != NULL && maxnode < nr_node_ids)
>  		return -EINVAL;
>  
> diff --git a/mm/mincore.c b/mm/mincore.c
> index c3f058bd0faf..64c322ed845c 100644
> --- a/mm/mincore.c
> +++ b/mm/mincore.c
> @@ -249,6 +249,8 @@ SYSCALL_DEFINE3(mincore, unsigned long, start, size_t, len,
>  	unsigned long pages;
>  	unsigned char *tmp;
>  
> +	start = untagged_addr(start);
> +
>  	/* Check the start address: needs to be page-aligned.. */
>  	if (start & ~PAGE_MASK)
>  		return -EINVAL;
> diff --git a/mm/mlock.c b/mm/mlock.c
> index 080f3b36415b..e82609eaa428 100644
> --- a/mm/mlock.c
> +++ b/mm/mlock.c
> @@ -674,6 +674,8 @@ static __must_check int do_mlock(unsigned long start, size_t len, vm_flags_t fla
>  	unsigned long lock_limit;
>  	int error = -ENOMEM;
>  
> +	start = untagged_addr(start);
> +
>  	if (!can_do_mlock())
>  		return -EPERM;
>  
> @@ -735,6 +737,8 @@ SYSCALL_DEFINE2(munlock, unsigned long, start, size_t, len)
>  {
>  	int ret;
>  
> +	start = untagged_addr(start);
> +
>  	len = PAGE_ALIGN(len + (offset_in_page(start)));
>  	start &= PAGE_MASK;
>  
> diff --git a/mm/mprotect.c b/mm/mprotect.c
> index bf38dfbbb4b4..19f981b733bc 100644
> --- a/mm/mprotect.c
> +++ b/mm/mprotect.c
> @@ -465,6 +465,8 @@ static int do_mprotect_pkey(unsigned long start, size_t len,
>  	const bool rier = (current->personality & READ_IMPLIES_EXEC) &&
>  				(prot & PROT_READ);
>  
> +	start = untagged_addr(start);
> +
>  	prot &= ~(PROT_GROWSDOWN|PROT_GROWSUP);
>  	if (grows == (PROT_GROWSDOWN|PROT_GROWSUP)) /* can't be both */
>  		return -EINVAL;
> diff --git a/mm/mremap.c b/mm/mremap.c
> index fc241d23cd97..1d98281f7204 100644
> --- a/mm/mremap.c
> +++ b/mm/mremap.c
> @@ -606,6 +606,8 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
>  	LIST_HEAD(uf_unmap_early);
>  	LIST_HEAD(uf_unmap);
>  
> +	addr = untagged_addr(addr);
> +
>  	if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE))
>  		return ret;
>  
> diff --git a/mm/msync.c b/mm/msync.c
> index ef30a429623a..c3bd3e75f687 100644
> --- a/mm/msync.c
> +++ b/mm/msync.c
> @@ -37,6 +37,8 @@ SYSCALL_DEFINE3(msync, unsigned long, start, size_t, len, int, flags)
>  	int unmapped_error = 0;
>  	int error = -EINVAL;
>  
> +	start = untagged_addr(start);
> +
>  	if (flags & ~(MS_ASYNC | MS_INVALIDATE | MS_SYNC))
>  		goto out;
>  	if (offset_in_page(start))
> -- 
> 2.22.0.rc1.311.g5d7573a151-goog
> 

-- 
Kees Cook

Re: [PATCH v16 13/16] media/v4l2-core, arm64: untag user pointers in videobuf_dma_contig_user_get

[Kees Cook]

On Mon, Jun 03, 2019 at 06:55:15PM +0200, Andrey Konovalov wrote:
> This patch is a part of a series that extends arm64 kernel ABI to allow to
> pass tagged user pointers (with the top byte set to something else other
> than 0x00) as syscall arguments.
> 
> videobuf_dma_contig_user_get() uses provided user pointers for vma
> lookups, which can only by done with untagged pointers.
> 
> Untag the pointers in this function.
> 
> Acked-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

> ---
>  drivers/media/v4l2-core/videobuf-dma-contig.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/media/v4l2-core/videobuf-dma-contig.c b/drivers/media/v4l2-core/videobuf-dma-contig.c
> index e1bf50df4c70..8a1ddd146b17 100644
> --- a/drivers/media/v4l2-core/videobuf-dma-contig.c
> +++ b/drivers/media/v4l2-core/videobuf-dma-contig.c
> @@ -160,6 +160,7 @@ static void videobuf_dma_contig_user_put(struct videobuf_dma_contig_memory *mem)
>  static int videobuf_dma_contig_user_get(struct videobuf_dma_contig_memory *mem,
>  					struct videobuf_buffer *vb)
>  {
> +	unsigned long untagged_baddr = untagged_addr(vb->baddr);
>  	struct mm_struct *mm = current->mm;
>  	struct vm_area_struct *vma;
>  	unsigned long prev_pfn, this_pfn;
> @@ -167,22 +168,22 @@ static int videobuf_dma_contig_user_get(struct videobuf_dma_contig_memory *mem,
>  	unsigned int offset;
>  	int ret;
>  
> -	offset = vb->baddr & ~PAGE_MASK;
> +	offset = untagged_baddr & ~PAGE_MASK;
>  	mem->size = PAGE_ALIGN(vb->size + offset);
>  	ret = -EINVAL;
>  
>  	down_read(&mm->mmap_sem);
>  
> -	vma = find_vma(mm, vb->baddr);
> +	vma = find_vma(mm, untagged_baddr);
>  	if (!vma)
>  		goto out_up;
>  
> -	if ((vb->baddr + mem->size) > vma->vm_end)
> +	if ((untagged_baddr + mem->size) > vma->vm_end)
>  		goto out_up;
>  
>  	pages_done = 0;
>  	prev_pfn = 0; /* kill warning */
> -	user_address = vb->baddr;
> +	user_address = untagged_baddr;
>  
>  	while (pages_done < (mem->size >> PAGE_SHIFT)) {
>  		ret = follow_pfn(vma, user_address, &this_pfn);
> -- 
> 2.22.0.rc1.311.g5d7573a151-goog
> 

-- 
Kees Cook

Re: [PATCH v16 16/16] selftests, arm64: add a selftest for passing tagged pointers to kernel

[Kees Cook]

On Mon, Jun 03, 2019 at 06:55:18PM +0200, Andrey Konovalov wrote:
> This patch is a part of a series that extends arm64 kernel ABI to allow to
> pass tagged user pointers (with the top byte set to something else other
> than 0x00) as syscall arguments.
> 
> This patch adds a simple test, that calls the uname syscall with a
> tagged user pointer as an argument. Without the kernel accepting tagged
> user pointers the test fails with EFAULT.
> 
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

I'm adding Shuah to CC in case she has some suggestions about the new
selftest.

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

> ---
>  tools/testing/selftests/arm64/.gitignore      |  1 +
>  tools/testing/selftests/arm64/Makefile        | 22 ++++++++++
>  .../testing/selftests/arm64/run_tags_test.sh  | 12 ++++++
>  tools/testing/selftests/arm64/tags_lib.c      | 42 +++++++++++++++++++
>  tools/testing/selftests/arm64/tags_test.c     | 18 ++++++++
>  5 files changed, 95 insertions(+)
>  create mode 100644 tools/testing/selftests/arm64/.gitignore
>  create mode 100644 tools/testing/selftests/arm64/Makefile
>  create mode 100755 tools/testing/selftests/arm64/run_tags_test.sh
>  create mode 100644 tools/testing/selftests/arm64/tags_lib.c
>  create mode 100644 tools/testing/selftests/arm64/tags_test.c
> 
> diff --git a/tools/testing/selftests/arm64/.gitignore b/tools/testing/selftests/arm64/.gitignore
> new file mode 100644
> index 000000000000..e8fae8d61ed6
> --- /dev/null
> +++ b/tools/testing/selftests/arm64/.gitignore
> @@ -0,0 +1 @@
> +tags_test
> diff --git a/tools/testing/selftests/arm64/Makefile b/tools/testing/selftests/arm64/Makefile
> new file mode 100644
> index 000000000000..9dee18727923
> --- /dev/null
> +++ b/tools/testing/selftests/arm64/Makefile
> @@ -0,0 +1,22 @@
> +# SPDX-License-Identifier: GPL-2.0
> +
> +include ../lib.mk
> +
> +# ARCH can be overridden by the user for cross compiling
> +ARCH ?= $(shell uname -m 2>/dev/null || echo not)
> +
> +ifneq (,$(filter $(ARCH),aarch64 arm64))
> +
> +TEST_CUSTOM_PROGS := $(OUTPUT)/tags_test
> +
> +$(OUTPUT)/tags_test: tags_test.c $(OUTPUT)/tags_lib.so
> +	$(CC) -o $@ $(CFLAGS) $(LDFLAGS) $<
> +
> +$(OUTPUT)/tags_lib.so: tags_lib.c
> +	$(CC) -o $@ -shared $(CFLAGS) $(LDFLAGS) $^
> +
> +TEST_PROGS := run_tags_test.sh
> +
> +all: $(TEST_CUSTOM_PROGS)
> +
> +endif
> diff --git a/tools/testing/selftests/arm64/run_tags_test.sh b/tools/testing/selftests/arm64/run_tags_test.sh
> new file mode 100755
> index 000000000000..2bbe0cd4220b
> --- /dev/null
> +++ b/tools/testing/selftests/arm64/run_tags_test.sh
> @@ -0,0 +1,12 @@
> +#!/bin/sh
> +# SPDX-License-Identifier: GPL-2.0
> +
> +echo "--------------------"
> +echo "running tags test"
> +echo "--------------------"
> +LD_PRELOAD=./tags_lib.so ./tags_test
> +if [ $? -ne 0 ]; then
> +	echo "[FAIL]"
> +else
> +	echo "[PASS]"
> +fi
> diff --git a/tools/testing/selftests/arm64/tags_lib.c b/tools/testing/selftests/arm64/tags_lib.c
> new file mode 100644
> index 000000000000..8a674509216e
> --- /dev/null
> +++ b/tools/testing/selftests/arm64/tags_lib.c
> @@ -0,0 +1,42 @@
> +#include <stdlib.h>
> +
> +#define TAG_SHIFT	(56)
> +#define TAG_MASK	(0xffUL << TAG_SHIFT)
> +
> +void *__libc_malloc(size_t size);
> +void __libc_free(void *ptr);
> +void *__libc_realloc(void *ptr, size_t size);
> +void *__libc_calloc(size_t nmemb, size_t size);
> +
> +static void *tag_ptr(void *ptr)
> +{
> +	unsigned long tag = rand() & 0xff;
> +	if (!ptr)
> +		return ptr;
> +	return (void *)((unsigned long)ptr | (tag << TAG_SHIFT));
> +}
> +
> +static void *untag_ptr(void *ptr)
> +{
> +	return (void *)((unsigned long)ptr & ~TAG_MASK);
> +}
> +
> +void *malloc(size_t size)
> +{
> +	return tag_ptr(__libc_malloc(size));
> +}
> +
> +void free(void *ptr)
> +{
> +	__libc_free(untag_ptr(ptr));
> +}
> +
> +void *realloc(void *ptr, size_t size)
> +{
> +	return tag_ptr(__libc_realloc(untag_ptr(ptr), size));
> +}
> +
> +void *calloc(size_t nmemb, size_t size)
> +{
> +	return tag_ptr(__libc_calloc(nmemb, size));
> +}
> diff --git a/tools/testing/selftests/arm64/tags_test.c b/tools/testing/selftests/arm64/tags_test.c
> new file mode 100644
> index 000000000000..263b302874ed
> --- /dev/null
> +++ b/tools/testing/selftests/arm64/tags_test.c
> @@ -0,0 +1,18 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <unistd.h>
> +#include <stdint.h>
> +#include <sys/utsname.h>
> +
> +int main(void)
> +{
> +	struct utsname *ptr;
> +	int err;
> +
> +	ptr = (struct utsname *)malloc(sizeof(*ptr));
> +	err = uname(ptr);
> +	free(ptr);
> +	return err;
> +}
> -- 
> 2.22.0.rc1.311.g5d7573a151-goog
> 

-- 
Kees Cook

Re: [PATCH v16 15/16] vfio/type1, arm64: untag user pointers in vaddr_get_pfn

[Kees Cook]

On Mon, Jun 03, 2019 at 06:55:17PM +0200, Andrey Konovalov wrote:
> This patch is a part of a series that extends arm64 kernel ABI to allow to
> pass tagged user pointers (with the top byte set to something else other
> than 0x00) as syscall arguments.
> 
> vaddr_get_pfn() uses provided user pointers for vma lookups, which can
> only by done with untagged pointers.
> 
> Untag user pointers in this function.
> 
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

> ---
>  drivers/vfio/vfio_iommu_type1.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index 3ddc375e7063..528e39a1c2dd 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -384,6 +384,8 @@ static int vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr,
>  
>  	down_read(&mm->mmap_sem);
>  
> +	vaddr = untagged_addr(vaddr);
> +
>  	vma = find_vma_intersection(mm, vaddr, vaddr + 1);
>  
>  	if (vma && vma->vm_flags & VM_PFNMAP) {
> -- 
> 2.22.0.rc1.311.g5d7573a151-goog
> 

-- 
Kees Cook

Re: [PATCH v16 06/16] mm, arm64: untag user pointers in mm/gup.c

[Kees Cook]

On Mon, Jun 03, 2019 at 06:55:08PM +0200, Andrey Konovalov wrote:
> This patch is a part of a series that extends arm64 kernel ABI to allow to
> pass tagged user pointers (with the top byte set to something else other
> than 0x00) as syscall arguments.
> 
> mm/gup.c provides a kernel interface that accepts user addresses and
> manipulates user pages directly (for example get_user_pages, that is used
> by the futex syscall). Since a user can provided tagged addresses, we need
> to handle this case.
> 
> Add untagging to gup.c functions that use user addresses for vma lookups.
> 
> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

> ---
>  mm/gup.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/mm/gup.c b/mm/gup.c
> index ddde097cf9e4..c37df3d455a2 100644
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -802,6 +802,8 @@ static long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
>  	if (!nr_pages)
>  		return 0;
>  
> +	start = untagged_addr(start);
> +
>  	VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET));
>  
>  	/*
> @@ -964,6 +966,8 @@ int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm,
>  	struct vm_area_struct *vma;
>  	vm_fault_t ret, major = 0;
>  
> +	address = untagged_addr(address);
> +
>  	if (unlocked)
>  		fault_flags |= FAULT_FLAG_ALLOW_RETRY;
>  
> -- 
> 2.22.0.rc1.311.g5d7573a151-goog
> 

-- 
Kees Cook

Re: [PATCH v16 07/16] mm, arm64: untag user pointers in get_vaddr_frames

[Kees Cook]

On Mon, Jun 03, 2019 at 06:55:09PM +0200, Andrey Konovalov wrote:
> This patch is a part of a series that extends arm64 kernel ABI to allow to
> pass tagged user pointers (with the top byte set to something else other
> than 0x00) as syscall arguments.
> 
> get_vaddr_frames uses provided user pointers for vma lookups, which can
> only by done with untagged pointers. Instead of locating and changing
> all callers of this function, perform untagging in it.
> 
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

> ---
>  mm/frame_vector.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/mm/frame_vector.c b/mm/frame_vector.c
> index c64dca6e27c2..c431ca81dad5 100644
> --- a/mm/frame_vector.c
> +++ b/mm/frame_vector.c
> @@ -46,6 +46,8 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames,
>  	if (WARN_ON_ONCE(nr_frames > vec->nr_allocated))
>  		nr_frames = vec->nr_allocated;
>  
> +	start = untagged_addr(start);
> +
>  	down_read(&mm->mmap_sem);
>  	locked = 1;
>  	vma = find_vma_intersection(mm, start, start + 1);
> -- 
> 2.22.0.rc1.311.g5d7573a151-goog
> 

-- 
Kees Cook

Re: [PATCH v16 08/16] fs, arm64: untag user pointers in copy_mount_options

[Kees Cook]

On Mon, Jun 03, 2019 at 06:55:10PM +0200, Andrey Konovalov wrote:
> This patch is a part of a series that extends arm64 kernel ABI to allow to
> pass tagged user pointers (with the top byte set to something else other
> than 0x00) as syscall arguments.
> 
> In copy_mount_options a user address is being subtracted from TASK_SIZE.
> If the address is lower than TASK_SIZE, the size is calculated to not
> allow the exact_copy_from_user() call to cross TASK_SIZE boundary.
> However if the address is tagged, then the size will be calculated
> incorrectly.
> 
> Untag the address before subtracting.
> 
> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

One thing I just noticed in the commit titles... "arm64" is in the
prefix, but these are arch-indep areas. Should the ", arm64" be left
out?

I would expect, instead:

	fs/namespace: untag user pointers in copy_mount_options

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

> ---
>  fs/namespace.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/namespace.c b/fs/namespace.c
> index b26778bdc236..2e85712a19ed 100644
> --- a/fs/namespace.c
> +++ b/fs/namespace.c
> @@ -2993,7 +2993,7 @@ void *copy_mount_options(const void __user * data)
>  	 * the remainder of the page.
>  	 */
>  	/* copy_from_user cannot cross TASK_SIZE ! */
> -	size = TASK_SIZE - (unsigned long)data;
> +	size = TASK_SIZE - (unsigned long)untagged_addr(data);
>  	if (size > PAGE_SIZE)
>  		size = PAGE_SIZE;
>  
> -- 
> 2.22.0.rc1.311.g5d7573a151-goog
> 

-- 
Kees Cook

Re: [PATCH v16 09/16] fs, arm64: untag user pointers in fs/userfaultfd.c

[Kees Cook]

On Mon, Jun 03, 2019 at 06:55:11PM +0200, Andrey Konovalov wrote:
> This patch is a part of a series that extends arm64 kernel ABI to allow to
> pass tagged user pointers (with the top byte set to something else other
> than 0x00) as syscall arguments.
> 
> userfaultfd code use provided user pointers for vma lookups, which can
> only by done with untagged pointers.
> 
> Untag user pointers in validate_range().
> 
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

"userfaultfd: untag user pointers"

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

> ---
>  fs/userfaultfd.c | 22 ++++++++++++----------
>  1 file changed, 12 insertions(+), 10 deletions(-)
> 
> diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
> index 3b30301c90ec..24d68c3b5ee2 100644
> --- a/fs/userfaultfd.c
> +++ b/fs/userfaultfd.c
> @@ -1263,21 +1263,23 @@ static __always_inline void wake_userfault(struct userfaultfd_ctx *ctx,
>  }
>  
>  static __always_inline int validate_range(struct mm_struct *mm,
> -					  __u64 start, __u64 len)
> +					  __u64 *start, __u64 len)
>  {
>  	__u64 task_size = mm->task_size;
>  
> -	if (start & ~PAGE_MASK)
> +	*start = untagged_addr(*start);
> +
> +	if (*start & ~PAGE_MASK)
>  		return -EINVAL;
>  	if (len & ~PAGE_MASK)
>  		return -EINVAL;
>  	if (!len)
>  		return -EINVAL;
> -	if (start < mmap_min_addr)
> +	if (*start < mmap_min_addr)
>  		return -EINVAL;
> -	if (start >= task_size)
> +	if (*start >= task_size)
>  		return -EINVAL;
> -	if (len > task_size - start)
> +	if (len > task_size - *start)
>  		return -EINVAL;
>  	return 0;
>  }
> @@ -1327,7 +1329,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
>  		goto out;
>  	}
>  
> -	ret = validate_range(mm, uffdio_register.range.start,
> +	ret = validate_range(mm, &uffdio_register.range.start,
>  			     uffdio_register.range.len);
>  	if (ret)
>  		goto out;
> @@ -1516,7 +1518,7 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
>  	if (copy_from_user(&uffdio_unregister, buf, sizeof(uffdio_unregister)))
>  		goto out;
>  
> -	ret = validate_range(mm, uffdio_unregister.start,
> +	ret = validate_range(mm, &uffdio_unregister.start,
>  			     uffdio_unregister.len);
>  	if (ret)
>  		goto out;
> @@ -1667,7 +1669,7 @@ static int userfaultfd_wake(struct userfaultfd_ctx *ctx,
>  	if (copy_from_user(&uffdio_wake, buf, sizeof(uffdio_wake)))
>  		goto out;
>  
> -	ret = validate_range(ctx->mm, uffdio_wake.start, uffdio_wake.len);
> +	ret = validate_range(ctx->mm, &uffdio_wake.start, uffdio_wake.len);
>  	if (ret)
>  		goto out;
>  
> @@ -1707,7 +1709,7 @@ static int userfaultfd_copy(struct userfaultfd_ctx *ctx,
>  			   sizeof(uffdio_copy)-sizeof(__s64)))
>  		goto out;
>  
> -	ret = validate_range(ctx->mm, uffdio_copy.dst, uffdio_copy.len);
> +	ret = validate_range(ctx->mm, &uffdio_copy.dst, uffdio_copy.len);
>  	if (ret)
>  		goto out;
>  	/*
> @@ -1763,7 +1765,7 @@ static int userfaultfd_zeropage(struct userfaultfd_ctx *ctx,
>  			   sizeof(uffdio_zeropage)-sizeof(__s64)))
>  		goto out;
>  
> -	ret = validate_range(ctx->mm, uffdio_zeropage.range.start,
> +	ret = validate_range(ctx->mm, &uffdio_zeropage.range.start,
>  			     uffdio_zeropage.range.len);
>  	if (ret)
>  		goto out;
> -- 
> 2.22.0.rc1.311.g5d7573a151-goog
> 

-- 
Kees Cook

Re: [PATCH v16 14/16] tee, arm64: untag user pointers in tee_shm_register

[Kees Cook]

On Mon, Jun 03, 2019 at 06:55:16PM +0200, Andrey Konovalov wrote:
> This patch is a part of a series that extends arm64 kernel ABI to allow to
> pass tagged user pointers (with the top byte set to something else other
> than 0x00) as syscall arguments.
> 
> tee_shm_register()->optee_shm_unregister()->check_mem_type() uses provided
> user pointers for vma lookups (via __check_mem_type()), which can only by
> done with untagged pointers.
> 
> Untag user pointers in this function.
> 
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

"tee: shm: untag user pointers in tee_shm_register"

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

> ---
>  drivers/tee/tee_shm.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/tee/tee_shm.c b/drivers/tee/tee_shm.c
> index 49fd7312e2aa..96945f4cefb8 100644
> --- a/drivers/tee/tee_shm.c
> +++ b/drivers/tee/tee_shm.c
> @@ -263,6 +263,7 @@ struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
>  	shm->teedev = teedev;
>  	shm->ctx = ctx;
>  	shm->id = -1;
> +	addr = untagged_addr(addr);
>  	start = rounddown(addr, PAGE_SIZE);
>  	shm->offset = addr - start;
>  	shm->size = length;
> -- 
> 2.22.0.rc1.311.g5d7573a151-goog
> 

-- 
Kees Cook

Re: [PATCH v16 05/16] arm64: untag user pointers passed to memory syscalls

[Catalin Marinas]

On Mon, Jun 03, 2019 at 06:55:07PM +0200, Andrey Konovalov wrote:
> This patch is a part of a series that extends arm64 kernel ABI to allow to
> pass tagged user pointers (with the top byte set to something else other
> than 0x00) as syscall arguments.
> 
> This patch allows tagged pointers to be passed to the following memory
> syscalls: get_mempolicy, madvise, mbind, mincore, mlock, mlock2, mprotect,
> mremap, msync, munlock.
> 
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

I would add in the commit log (and possibly in the code with a comment)
that mremap() and mmap() do not currently accept tagged hint addresses.
Architectures may interpret the hint tag as a background colour for the
corresponding vma. With this:

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>

-- 
Catalin

Re: [PATCH v16 07/16] mm, arm64: untag user pointers in get_vaddr_frames

[Catalin Marinas]

On Mon, Jun 03, 2019 at 06:55:09PM +0200, Andrey Konovalov wrote:
> This patch is a part of a series that extends arm64 kernel ABI to allow to
> pass tagged user pointers (with the top byte set to something else other
> than 0x00) as syscall arguments.
> 
> get_vaddr_frames uses provided user pointers for vma lookups, which can
> only by done with untagged pointers. Instead of locating and changing
> all callers of this function, perform untagging in it.
> 
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

Acked-by: Catalin Marinas <catalin.marinas@arm.com>

Re: [PATCH v16 02/16] arm64: untag user pointers in access_ok and __uaccess_mask_ptr

[Catalin Marinas]

On Mon, Jun 03, 2019 at 06:55:04PM +0200, Andrey Konovalov wrote:
> diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
> index e5d5f31c6d36..9164ecb5feca 100644
> --- a/arch/arm64/include/asm/uaccess.h
> +++ b/arch/arm64/include/asm/uaccess.h
> @@ -94,7 +94,7 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si
>  	return ret;
>  }
>  
> -#define access_ok(addr, size)	__range_ok(addr, size)
> +#define access_ok(addr, size)	__range_ok(untagged_addr(addr), size)

I'm going to propose an opt-in method here (RFC for now). We can't have
a check in untagged_addr() since this is already used throughout the
kernel for both user and kernel addresses (khwasan) but we can add one
in __range_ok(). The same prctl() option will be used for controlling
the precise/imprecise mode of MTE later on. We can use a TIF_ flag here
assuming that this will be called early on and any cloned thread will
inherit this.

Anyway, it's easier to paste some diff than explain but Vincenzo can
fold them into his ABI patches that should really go together with
these. I added a couple of MTE definitions for prctl() as an example,
not used currently:

------------------8<---------------------------------------------
diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index fcd0e691b1ea..2d4cb7e4edab 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -307,6 +307,10 @@ extern void __init minsigstksz_setup(void);
 /* PR_PAC_RESET_KEYS prctl */
 #define PAC_RESET_KEYS(tsk, arg)	ptrauth_prctl_reset_keys(tsk, arg)
 
+/* PR_UNTAGGED_UADDR prctl */
+int untagged_uaddr_set_mode(unsigned long arg);
+#define SET_UNTAGGED_UADDR_MODE(arg)	untagged_uaddr_set_mode(arg)
+
 /*
  * For CONFIG_GCC_PLUGIN_STACKLEAK
  *
diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
index c285d1ce7186..89ce77773c49 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -101,6 +101,7 @@ void arch_release_task_struct(struct task_struct *tsk);
 #define TIF_SVE			23	/* Scalable Vector Extension in use */
 #define TIF_SVE_VL_INHERIT	24	/* Inherit sve_vl_onexec across exec */
 #define TIF_SSBD		25	/* Wants SSB mitigation */
+#define TIF_UNTAGGED_UADDR	26
 
 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
@@ -116,6 +117,7 @@ void arch_release_task_struct(struct task_struct *tsk);
 #define _TIF_FSCHECK		(1 << TIF_FSCHECK)
 #define _TIF_32BIT		(1 << TIF_32BIT)
 #define _TIF_SVE		(1 << TIF_SVE)
+#define _TIF_UNTAGGED_UADDR	(1 << TIF_UNTAGGED_UADDR)
 
 #define _TIF_WORK_MASK		(_TIF_NEED_RESCHED | _TIF_SIGPENDING | \
 				 _TIF_NOTIFY_RESUME | _TIF_FOREIGN_FPSTATE | \
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index 9164ecb5feca..54f5bbaebbc4 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -73,6 +73,9 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si
 {
 	unsigned long ret, limit = current_thread_info()->addr_limit;
 
+	if (test_thread_flag(TIF_UNTAGGED_UADDR))
+		addr = untagged_addr(addr);
+
 	__chk_user_ptr(addr);
 	asm volatile(
 	// A + B <= C + 1 for all A,B,C, in four easy steps:
@@ -94,7 +97,7 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si
 	return ret;
 }
 
-#define access_ok(addr, size)	__range_ok(untagged_addr(addr), size)
+#define access_ok(addr, size)	__range_ok(addr, size)
 #define user_addr_max			get_fs
 
 #define _ASM_EXTABLE(from, to)						\
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 3767fb21a5b8..fd191c5b92aa 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -552,3 +552,18 @@ void arch_setup_new_exec(void)
 
 	ptrauth_thread_init_user(current);
 }
+
+/*
+ * Enable the relaxed ABI allowing tagged user addresses into the kernel.
+ */
+int untagged_uaddr_set_mode(unsigned long arg)
+{
+	if (is_compat_task())
+		return -ENOTSUPP;
+	if (arg)
+		return -EINVAL;
+
+	set_thread_flag(TIF_UNTAGGED_UADDR);
+
+	return 0;
+}
diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h
index 094bb03b9cc2..4afd5e2980ee 100644
--- a/include/uapi/linux/prctl.h
+++ b/include/uapi/linux/prctl.h
@@ -229,4 +229,9 @@ struct prctl_mm_map {
 # define PR_PAC_APDBKEY			(1UL << 3)
 # define PR_PAC_APGAKEY			(1UL << 4)
 
+/* Untagged user addresses for arm64 */
+#define PR_UNTAGGED_UADDR		55
+# define PR_MTE_IMPRECISE_CHECK		0
+# define PR_MTE_PRECISE_CHECK		1
+
 #endif /* _LINUX_PRCTL_H */
diff --git a/kernel/sys.c b/kernel/sys.c
index 2969304c29fe..b1f67a8cffc4 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -124,6 +124,9 @@
 #ifndef PAC_RESET_KEYS
 # define PAC_RESET_KEYS(a, b)	(-EINVAL)
 #endif
+#ifndef SET_UNTAGGED_UADDR_MODE
+# define SET_UNTAGGED_UADDR_MODE	(-EINVAL)
+#endif
 
 /*
  * this is where the system-wide overflow UID and GID are defined, for
@@ -2492,6 +2495,11 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
 			return -EINVAL;
 		error = PAC_RESET_KEYS(me, arg2);
 		break;
+	case PR_UNTAGGED_UADDR:
+		if (arg3 || arg4 || arg5)
+			return -EINVAL;
+		error = SET_UNTAGGED_UADDR_MODE(arg2);
+		break;
 	default:
 		error = -EINVAL;
 		break;
------------------8<---------------------------------------------

The tag_ptr() function in the test library would become:

static void *tag_ptr(void *ptr)
{
	static int tbi_enabled = 0;
	unsigned long tag = 0;

	if (!tbi_enabled) {
		if (prctl(PR_UNTAGGED_UADDR, 0, 0, 0, 0) == 0)
			tbi_enabled = 1;
	}

	if (!ptr)
		return ptr;
	if (tbi_enabled)
		tag = rand() & 0xff;

	return (void *)((unsigned long)ptr | (tag << TAG_SHIFT));
}

-- 
Catalin

Re: [PATCH v16 02/16] arm64: untag user pointers in access_ok and __uaccess_mask_ptr

[Kees Cook]

On Mon, Jun 10, 2019 at 06:53:27PM +0100, Catalin Marinas wrote:
> On Mon, Jun 03, 2019 at 06:55:04PM +0200, Andrey Konovalov wrote:
> > diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
> > index e5d5f31c6d36..9164ecb5feca 100644
> > --- a/arch/arm64/include/asm/uaccess.h
> > +++ b/arch/arm64/include/asm/uaccess.h
> > @@ -94,7 +94,7 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si
> >  	return ret;
> >  }
> >  
> > -#define access_ok(addr, size)	__range_ok(addr, size)
> > +#define access_ok(addr, size)	__range_ok(untagged_addr(addr), size)
> 
> I'm going to propose an opt-in method here (RFC for now). We can't have
> a check in untagged_addr() since this is already used throughout the
> kernel for both user and kernel addresses (khwasan) but we can add one
> in __range_ok(). The same prctl() option will be used for controlling
> the precise/imprecise mode of MTE later on. We can use a TIF_ flag here
> assuming that this will be called early on and any cloned thread will
> inherit this.
> 
> Anyway, it's easier to paste some diff than explain but Vincenzo can
> fold them into his ABI patches that should really go together with
> these. I added a couple of MTE definitions for prctl() as an example,
> not used currently:
> 
> ------------------8<---------------------------------------------
> diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
> index fcd0e691b1ea..2d4cb7e4edab 100644
> --- a/arch/arm64/include/asm/processor.h
> +++ b/arch/arm64/include/asm/processor.h
> @@ -307,6 +307,10 @@ extern void __init minsigstksz_setup(void);
>  /* PR_PAC_RESET_KEYS prctl */
>  #define PAC_RESET_KEYS(tsk, arg)	ptrauth_prctl_reset_keys(tsk, arg)
>  
> +/* PR_UNTAGGED_UADDR prctl */
> +int untagged_uaddr_set_mode(unsigned long arg);
> +#define SET_UNTAGGED_UADDR_MODE(arg)	untagged_uaddr_set_mode(arg)
> +
>  /*
>   * For CONFIG_GCC_PLUGIN_STACKLEAK
>   *
> diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
> index c285d1ce7186..89ce77773c49 100644
> --- a/arch/arm64/include/asm/thread_info.h
> +++ b/arch/arm64/include/asm/thread_info.h
> @@ -101,6 +101,7 @@ void arch_release_task_struct(struct task_struct *tsk);
>  #define TIF_SVE			23	/* Scalable Vector Extension in use */
>  #define TIF_SVE_VL_INHERIT	24	/* Inherit sve_vl_onexec across exec */
>  #define TIF_SSBD		25	/* Wants SSB mitigation */
> +#define TIF_UNTAGGED_UADDR	26
>  
>  #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
>  #define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
> @@ -116,6 +117,7 @@ void arch_release_task_struct(struct task_struct *tsk);
>  #define _TIF_FSCHECK		(1 << TIF_FSCHECK)
>  #define _TIF_32BIT		(1 << TIF_32BIT)
>  #define _TIF_SVE		(1 << TIF_SVE)
> +#define _TIF_UNTAGGED_UADDR	(1 << TIF_UNTAGGED_UADDR)
>  
>  #define _TIF_WORK_MASK		(_TIF_NEED_RESCHED | _TIF_SIGPENDING | \
>  				 _TIF_NOTIFY_RESUME | _TIF_FOREIGN_FPSTATE | \
> diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
> index 9164ecb5feca..54f5bbaebbc4 100644
> --- a/arch/arm64/include/asm/uaccess.h
> +++ b/arch/arm64/include/asm/uaccess.h
> @@ -73,6 +73,9 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si
>  {
>  	unsigned long ret, limit = current_thread_info()->addr_limit;
>  
> +	if (test_thread_flag(TIF_UNTAGGED_UADDR))
> +		addr = untagged_addr(addr);
> +
>  	__chk_user_ptr(addr);
>  	asm volatile(
>  	// A + B <= C + 1 for all A,B,C, in four easy steps:
> @@ -94,7 +97,7 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si
>  	return ret;
>  }
>  
> -#define access_ok(addr, size)	__range_ok(untagged_addr(addr), size)
> +#define access_ok(addr, size)	__range_ok(addr, size)
>  #define user_addr_max			get_fs
>  
>  #define _ASM_EXTABLE(from, to)						\
> diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
> index 3767fb21a5b8..fd191c5b92aa 100644
> --- a/arch/arm64/kernel/process.c
> +++ b/arch/arm64/kernel/process.c
> @@ -552,3 +552,18 @@ void arch_setup_new_exec(void)
>  
>  	ptrauth_thread_init_user(current);
>  }
> +
> +/*
> + * Enable the relaxed ABI allowing tagged user addresses into the kernel.
> + */
> +int untagged_uaddr_set_mode(unsigned long arg)
> +{
> +	if (is_compat_task())
> +		return -ENOTSUPP;
> +	if (arg)
> +		return -EINVAL;
> +
> +	set_thread_flag(TIF_UNTAGGED_UADDR);
> +
> +	return 0;
> +}

I think this should be paired with a flag clearing in copy_thread(),
yes? (i.e. each binary needs to opt in)

-- 
Kees Cook

Re: [PATCH v16 02/16] arm64: untag user pointers in access_ok and __uaccess_mask_ptr

[Catalin Marinas]

On Mon, Jun 10, 2019 at 11:07:03AM -0700, Kees Cook wrote:
> On Mon, Jun 10, 2019 at 06:53:27PM +0100, Catalin Marinas wrote:
> > On Mon, Jun 03, 2019 at 06:55:04PM +0200, Andrey Konovalov wrote:
> > > diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
> > > index e5d5f31c6d36..9164ecb5feca 100644
> > > --- a/arch/arm64/include/asm/uaccess.h
> > > +++ b/arch/arm64/include/asm/uaccess.h
> > > @@ -94,7 +94,7 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si
> > >  	return ret;
> > >  }
> > >  
> > > -#define access_ok(addr, size)	__range_ok(addr, size)
> > > +#define access_ok(addr, size)	__range_ok(untagged_addr(addr), size)
[...]
> > diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
> > index 3767fb21a5b8..fd191c5b92aa 100644
> > --- a/arch/arm64/kernel/process.c
> > +++ b/arch/arm64/kernel/process.c
> > @@ -552,3 +552,18 @@ void arch_setup_new_exec(void)
> >  
> >  	ptrauth_thread_init_user(current);
> >  }
> > +
> > +/*
> > + * Enable the relaxed ABI allowing tagged user addresses into the kernel.
> > + */
> > +int untagged_uaddr_set_mode(unsigned long arg)
> > +{
> > +	if (is_compat_task())
> > +		return -ENOTSUPP;
> > +	if (arg)
> > +		return -EINVAL;
> > +
> > +	set_thread_flag(TIF_UNTAGGED_UADDR);
> > +
> > +	return 0;
> > +}
> 
> I think this should be paired with a flag clearing in copy_thread(),
> yes? (i.e. each binary needs to opt in)

It indeed needs clearing though not in copy_thread() as that's used on
clone/fork but rather in flush_thread(), called on the execve() path.

And a note to myself: I think PR_UNTAGGED_ADDR (not UADDR) looks better
in a uapi header, the user doesn't differentiate between uaddr and
kaddr.

-- 
Catalin

Re: [PATCH v16 02/16] arm64: untag user pointers in access_ok and __uaccess_mask_ptr

[Kees Cook]

On Mon, Jun 10, 2019 at 07:53:30PM +0100, Catalin Marinas wrote:
> On Mon, Jun 10, 2019 at 11:07:03AM -0700, Kees Cook wrote:
> > On Mon, Jun 10, 2019 at 06:53:27PM +0100, Catalin Marinas wrote:
> > > diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
> > > index 3767fb21a5b8..fd191c5b92aa 100644
> > > --- a/arch/arm64/kernel/process.c
> > > +++ b/arch/arm64/kernel/process.c
> > > @@ -552,3 +552,18 @@ void arch_setup_new_exec(void)
> > >  
> > >  	ptrauth_thread_init_user(current);
> > >  }
> > > +
> > > +/*
> > > + * Enable the relaxed ABI allowing tagged user addresses into the kernel.
> > > + */
> > > +int untagged_uaddr_set_mode(unsigned long arg)
> > > +{
> > > +	if (is_compat_task())
> > > +		return -ENOTSUPP;
> > > +	if (arg)
> > > +		return -EINVAL;
> > > +
> > > +	set_thread_flag(TIF_UNTAGGED_UADDR);
> > > +
> > > +	return 0;
> > > +}
> > 
> > I think this should be paired with a flag clearing in copy_thread(),
> > yes? (i.e. each binary needs to opt in)
> 
> It indeed needs clearing though not in copy_thread() as that's used on
> clone/fork but rather in flush_thread(), called on the execve() path.

Ah! Yes, thanks.

> And a note to myself: I think PR_UNTAGGED_ADDR (not UADDR) looks better
> in a uapi header, the user doesn't differentiate between uaddr and
> kaddr.

Good point. I would agree. :)

-- 
Kees Cook

Re: [PATCH v16 16/16] selftests, arm64: add a selftest for passing tagged pointers to kernel

[shuah]

On 6/7/19 9:56 PM, Kees Cook wrote:
> On Mon, Jun 03, 2019 at 06:55:18PM +0200, Andrey Konovalov wrote:
>> This patch is a part of a series that extends arm64 kernel ABI to allow to
>> pass tagged user pointers (with the top byte set to something else other
>> than 0x00) as syscall arguments.
>>
>> This patch adds a simple test, that calls the uname syscall with a
>> tagged user pointer as an argument. Without the kernel accepting tagged
>> user pointers the test fails with EFAULT.
>>
>> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> 
> I'm adding Shuah to CC in case she has some suggestions about the new
> selftest.

Thanks Kees.

> 
> Reviewed-by: Kees Cook <keescook@chromium.org>
> 
> -Kees
> 

Looks good to me.

Acked-by: Shuah Khan <skhan@linuxfoundation.org>

thanks,
-- Shuah

Re: [PATCH v16 08/16] fs, arm64: untag user pointers in copy_mount_options

[Andrey Konovalov]

On Sat, Jun 8, 2019 at 6:02 AM Kees Cook <keescook@chromium.org> wrote:
>
> On Mon, Jun 03, 2019 at 06:55:10PM +0200, Andrey Konovalov wrote:
> > This patch is a part of a series that extends arm64 kernel ABI to allow to
> > pass tagged user pointers (with the top byte set to something else other
> > than 0x00) as syscall arguments.
> >
> > In copy_mount_options a user address is being subtracted from TASK_SIZE.
> > If the address is lower than TASK_SIZE, the size is calculated to not
> > allow the exact_copy_from_user() call to cross TASK_SIZE boundary.
> > However if the address is tagged, then the size will be calculated
> > incorrectly.
> >
> > Untag the address before subtracting.
> >
> > Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
> > Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
>
> One thing I just noticed in the commit titles... "arm64" is in the
> prefix, but these are arch-indep areas. Should the ", arm64" be left
> out?
>
> I would expect, instead:
>
>         fs/namespace: untag user pointers in copy_mount_options

Hm, I've added the arm64 tag in all of the patches because they are
related to changes in arm64 kernel ABI. I can remove it from all the
patches that only touch common code if you think that it makes sense.

Thanks!

>
> Reviewed-by: Kees Cook <keescook@chromium.org>
>
> -Kees
>
> > ---
> >  fs/namespace.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/fs/namespace.c b/fs/namespace.c
> > index b26778bdc236..2e85712a19ed 100644
> > --- a/fs/namespace.c
> > +++ b/fs/namespace.c
> > @@ -2993,7 +2993,7 @@ void *copy_mount_options(const void __user * data)
> >        * the remainder of the page.
> >        */
> >       /* copy_from_user cannot cross TASK_SIZE ! */
> > -     size = TASK_SIZE - (unsigned long)data;
> > +     size = TASK_SIZE - (unsigned long)untagged_addr(data);
> >       if (size > PAGE_SIZE)
> >               size = PAGE_SIZE;
> >
> > --
> > 2.22.0.rc1.311.g5d7573a151-goog
> >
>
> --
> Kees Cook

Re: [PATCH v16 02/16] arm64: untag user pointers in access_ok and __uaccess_mask_ptr

[Catalin Marinas]

On Mon, Jun 10, 2019 at 06:53:27PM +0100, Catalin Marinas wrote:
> On Mon, Jun 03, 2019 at 06:55:04PM +0200, Andrey Konovalov wrote:
> > diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
> > index e5d5f31c6d36..9164ecb5feca 100644
> > --- a/arch/arm64/include/asm/uaccess.h
> > +++ b/arch/arm64/include/asm/uaccess.h
> > @@ -94,7 +94,7 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si
> >  	return ret;
> >  }
> >  
> > -#define access_ok(addr, size)	__range_ok(addr, size)
> > +#define access_ok(addr, size)	__range_ok(untagged_addr(addr), size)
> 
> I'm going to propose an opt-in method here (RFC for now). We can't have
> a check in untagged_addr() since this is already used throughout the
> kernel for both user and kernel addresses (khwasan) but we can add one
> in __range_ok(). The same prctl() option will be used for controlling
> the precise/imprecise mode of MTE later on. We can use a TIF_ flag here
> assuming that this will be called early on and any cloned thread will
> inherit this.

Updated patch, inlining it below. Once we agreed on the approach, I
think Andrey can insert in in this series, probably after patch 2. The
differences from the one I posted yesterday:

- renamed PR_* macros together with get/set variants and the possibility
  to disable the relaxed ABI

- sysctl option - /proc/sys/abi/tagged_addr to disable the ABI globally
  (just the prctl() opt-in, tasks already using it won't be affected)

And, of course, it needs more testing.

---------8<----------------
From 7c624777a4e545522dec1b34e60f0229cb2bd59f Mon Sep 17 00:00:00 2001
From: Catalin Marinas <catalin.marinas@arm.com>
Date: Tue, 11 Jun 2019 13:03:38 +0100
Subject: [PATCH] arm64: Introduce prctl() options to control the tagged user
 addresses ABI

It is not desirable to relax the ABI to allow tagged user addresses into
the kernel indiscriminately. This patch introduces a prctl() interface
for enabling or disabling the tagged ABI with a global sysctl control
for preventing applications from enabling the relaxed ABI (meant for
testing user-space prctl() return error checking without reconfiguring
the kernel). The ABI properties are inherited by threads of the same
application and fork()'ed children but cleared on execve().

The PR_SET_TAGGED_ADDR_CTRL will be expanded in the future to handle
MTE-specific settings like imprecise vs precise exceptions.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
---
 arch/arm64/include/asm/processor.h   |  6 +++
 arch/arm64/include/asm/thread_info.h |  1 +
 arch/arm64/include/asm/uaccess.h     |  5 ++-
 arch/arm64/kernel/process.c          | 67 ++++++++++++++++++++++++++++
 include/uapi/linux/prctl.h           |  5 +++
 kernel/sys.c                         | 16 +++++++
 6 files changed, 99 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index fcd0e691b1ea..fee457456aa8 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -307,6 +307,12 @@ extern void __init minsigstksz_setup(void);
 /* PR_PAC_RESET_KEYS prctl */
 #define PAC_RESET_KEYS(tsk, arg)	ptrauth_prctl_reset_keys(tsk, arg)
 
+/* PR_TAGGED_ADDR prctl */
+long set_tagged_addr_ctrl(unsigned long arg);
+long get_tagged_addr_ctrl(void);
+#define SET_TAGGED_ADDR_CTRL(arg)	set_tagged_addr_ctrl(arg)
+#define GET_TAGGED_ADDR_CTRL()		get_tagged_addr_ctrl()
+
 /*
  * For CONFIG_GCC_PLUGIN_STACKLEAK
  *
diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
index c285d1ce7186..7263d4c973ce 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -101,6 +101,7 @@ void arch_release_task_struct(struct task_struct *tsk);
 #define TIF_SVE			23	/* Scalable Vector Extension in use */
 #define TIF_SVE_VL_INHERIT	24	/* Inherit sve_vl_onexec across exec */
 #define TIF_SSBD		25	/* Wants SSB mitigation */
+#define TIF_TAGGED_ADDR		26
 
 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index 9164ecb5feca..995b9ea11a89 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -73,6 +73,9 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si
 {
 	unsigned long ret, limit = current_thread_info()->addr_limit;
 
+	if (test_thread_flag(TIF_TAGGED_ADDR))
+		addr = untagged_addr(addr);
+
 	__chk_user_ptr(addr);
 	asm volatile(
 	// A + B <= C + 1 for all A,B,C, in four easy steps:
@@ -94,7 +97,7 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si
 	return ret;
 }
 
-#define access_ok(addr, size)	__range_ok(untagged_addr(addr), size)
+#define access_ok(addr, size)	__range_ok(addr, size)
 #define user_addr_max			get_fs
 
 #define _ASM_EXTABLE(from, to)						\
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 3767fb21a5b8..69d0be1fc708 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -30,6 +30,7 @@
 #include <linux/kernel.h>
 #include <linux/mm.h>
 #include <linux/stddef.h>
+#include <linux/sysctl.h>
 #include <linux/unistd.h>
 #include <linux/user.h>
 #include <linux/delay.h>
@@ -323,6 +324,7 @@ void flush_thread(void)
 	fpsimd_flush_thread();
 	tls_thread_flush();
 	flush_ptrace_hw_breakpoint(current);
+	clear_thread_flag(TIF_TAGGED_ADDR);
 }
 
 void release_thread(struct task_struct *dead_task)
@@ -552,3 +554,68 @@ void arch_setup_new_exec(void)
 
 	ptrauth_thread_init_user(current);
 }
+
+/*
+ * Control the relaxed ABI allowing tagged user addresses into the kernel.
+ */
+static unsigned int tagged_addr_prctl_allowed = 1;
+
+long set_tagged_addr_ctrl(unsigned long arg)
+{
+	if (!tagged_addr_prctl_allowed)
+		return -EINVAL;
+	if (is_compat_task())
+		return -EINVAL;
+	if (arg & ~PR_TAGGED_ADDR_ENABLE)
+		return -EINVAL;
+
+	if (arg & PR_TAGGED_ADDR_ENABLE)
+		set_thread_flag(TIF_TAGGED_ADDR);
+	else
+		clear_thread_flag(TIF_TAGGED_ADDR);
+
+	return 0;
+}
+
+long get_tagged_addr_ctrl(void)
+{
+	if (!tagged_addr_prctl_allowed)
+		return -EINVAL;
+	if (is_compat_task())
+		return -EINVAL;
+
+	if (test_thread_flag(TIF_TAGGED_ADDR))
+		return PR_TAGGED_ADDR_ENABLE;
+
+	return 0;
+}
+
+/*
+ * Global sysctl to disable the tagged user addresses support. This control
+ * only prevents the tagged address ABI enabling via prctl() and does not
+ * disable it for tasks that already opted in to the relaxed ABI.
+ */
+static int zero;
+static int one = 1;
+
+static struct ctl_table tagged_addr_sysctl_table[] = {
+	{
+		.procname	= "tagged_addr",
+		.mode		= 0644,
+		.data		= &tagged_addr_prctl_allowed,
+		.maxlen		= sizeof(int),
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= &zero,
+		.extra2		= &one,
+	},
+	{ }
+};
+
+static int __init tagged_addr_init(void)
+{
+	if (!register_sysctl("abi", tagged_addr_sysctl_table))
+		return -EINVAL;
+	return 0;
+}
+
+core_initcall(tagged_addr_init);
diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h
index 094bb03b9cc2..2e927b3e9d6c 100644
--- a/include/uapi/linux/prctl.h
+++ b/include/uapi/linux/prctl.h
@@ -229,4 +229,9 @@ struct prctl_mm_map {
 # define PR_PAC_APDBKEY			(1UL << 3)
 # define PR_PAC_APGAKEY			(1UL << 4)
 
+/* Tagged user address controls for arm64 */
+#define PR_SET_TAGGED_ADDR_CTRL		55
+#define PR_GET_TAGGED_ADDR_CTRL		56
+# define PR_TAGGED_ADDR_ENABLE		(1UL << 0)
+
 #endif /* _LINUX_PRCTL_H */
diff --git a/kernel/sys.c b/kernel/sys.c
index 2969304c29fe..ec48396b4943 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -124,6 +124,12 @@
 #ifndef PAC_RESET_KEYS
 # define PAC_RESET_KEYS(a, b)	(-EINVAL)
 #endif
+#ifndef SET_TAGGED_ADDR_CTRL
+# define SET_TAGGED_ADDR_CTRL(a)	(-EINVAL)
+#endif
+#ifndef GET_TAGGED_ADDR_CTRL
+# define GET_TAGGED_ADDR_CTRL()		(-EINVAL)
+#endif
 
 /*
  * this is where the system-wide overflow UID and GID are defined, for
@@ -2492,6 +2498,16 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
 			return -EINVAL;
 		error = PAC_RESET_KEYS(me, arg2);
 		break;
+	case PR_SET_TAGGED_ADDR_CTRL:
+		if (arg3 || arg4 || arg5)
+			return -EINVAL;
+		error = SET_TAGGED_ADDR_CTRL(arg2);
+		break;
+	case PR_GET_TAGGED_ADDR_CTRL:
+		if (arg2 || arg3 || arg4 || arg5)
+			return -EINVAL;
+		error = GET_TAGGED_ADDR_CTRL();
+		break;
 	default:
 		error = -EINVAL;
 		break;

Re: [PATCH v16 16/16] selftests, arm64: add a selftest for passing tagged pointers to kernel

[Catalin Marinas]

On Mon, Jun 03, 2019 at 06:55:18PM +0200, Andrey Konovalov wrote:
> This patch is a part of a series that extends arm64 kernel ABI to allow to
> pass tagged user pointers (with the top byte set to something else other
> than 0x00) as syscall arguments.
> 
> This patch adds a simple test, that calls the uname syscall with a
> tagged user pointer as an argument. Without the kernel accepting tagged
> user pointers the test fails with EFAULT.
> 
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

BTW, you could add

Co-developed-by: Catalin Marinas <catalin.marinas@arm.com>

since I wrote the malloc() etc. hooks.


> +static void *tag_ptr(void *ptr)
> +{
> +	unsigned long tag = rand() & 0xff;
> +	if (!ptr)
> +		return ptr;
> +	return (void *)((unsigned long)ptr | (tag << TAG_SHIFT));
> +}

With the prctl() option, this function becomes (if you have a better
idea, fine by me):

----------8<---------------
#include <stdlib.h>
#include <sys/prctl.h>

#define TAG_SHIFT	(56)
#define TAG_MASK	(0xffUL << TAG_SHIFT)

#define PR_SET_TAGGED_ADDR_CTRL		55
#define PR_GET_TAGGED_ADDR_CTRL		56
# define PR_TAGGED_ADDR_ENABLE		(1UL << 0)

void *__libc_malloc(size_t size);
void __libc_free(void *ptr);
void *__libc_realloc(void *ptr, size_t size);
void *__libc_calloc(size_t nmemb, size_t size);

static void *tag_ptr(void *ptr)
{
	static int tagged_addr_err = 1;
	unsigned long tag = 0;

	if (tagged_addr_err == 1)
		tagged_addr_err = prctl(PR_SET_TAGGED_ADDR_CTRL,
					PR_TAGGED_ADDR_ENABLE, 0, 0, 0);

	if (!ptr)
		return ptr;
	if (!tagged_addr_err)
		tag = rand() & 0xff;

	return (void *)((unsigned long)ptr | (tag << TAG_SHIFT));
}

-- 
Catalin

Re: [PATCH v16 05/16] arm64: untag user pointers passed to memory syscalls

[Andrey Konovalov]

On Mon, Jun 10, 2019 at 4:28 PM Catalin Marinas <catalin.marinas@arm.com> wrote:
>
> On Mon, Jun 03, 2019 at 06:55:07PM +0200, Andrey Konovalov wrote:
> > This patch is a part of a series that extends arm64 kernel ABI to allow to
> > pass tagged user pointers (with the top byte set to something else other
> > than 0x00) as syscall arguments.
> >
> > This patch allows tagged pointers to be passed to the following memory
> > syscalls: get_mempolicy, madvise, mbind, mincore, mlock, mlock2, mprotect,
> > mremap, msync, munlock.
> >
> > Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
>
> I would add in the commit log (and possibly in the code with a comment)
> that mremap() and mmap() do not currently accept tagged hint addresses.
> Architectures may interpret the hint tag as a background colour for the
> corresponding vma. With this:

I'll change the commit log. Where do you you think I should put this
comment? Before mmap and mremap definitions in mm/?

Thanks!

>
> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
>
> --
> Catalin

Re: [PATCH v16 02/16] arm64: untag user pointers in access_ok and __uaccess_mask_ptr

[Vincenzo Frascino]

Hi Catalin,

...

> ---------8<----------------
> From 7c624777a4e545522dec1b34e60f0229cb2bd59f Mon Sep 17 00:00:00 2001
> From: Catalin Marinas <catalin.marinas@arm.com>
> Date: Tue, 11 Jun 2019 13:03:38 +0100
> Subject: [PATCH] arm64: Introduce prctl() options to control the tagged user
>  addresses ABI
> 
> It is not desirable to relax the ABI to allow tagged user addresses into
> the kernel indiscriminately. This patch introduces a prctl() interface
> for enabling or disabling the tagged ABI with a global sysctl control
> for preventing applications from enabling the relaxed ABI (meant for
> testing user-space prctl() return error checking without reconfiguring
> the kernel). The ABI properties are inherited by threads of the same
> application and fork()'ed children but cleared on execve().
> 
> The PR_SET_TAGGED_ADDR_CTRL will be expanded in the future to handle
> MTE-specific settings like imprecise vs precise exceptions.
> 
> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
> ---
>  arch/arm64/include/asm/processor.h   |  6 +++
>  arch/arm64/include/asm/thread_info.h |  1 +
>  arch/arm64/include/asm/uaccess.h     |  5 ++-
>  arch/arm64/kernel/process.c          | 67 ++++++++++++++++++++++++++++
>  include/uapi/linux/prctl.h           |  5 +++
>  kernel/sys.c                         | 16 +++++++
>  6 files changed, 99 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
> index fcd0e691b1ea..fee457456aa8 100644
> --- a/arch/arm64/include/asm/processor.h
> +++ b/arch/arm64/include/asm/processor.h
> @@ -307,6 +307,12 @@ extern void __init minsigstksz_setup(void);
>  /* PR_PAC_RESET_KEYS prctl */
>  #define PAC_RESET_KEYS(tsk, arg)	ptrauth_prctl_reset_keys(tsk, arg)
>  
> +/* PR_TAGGED_ADDR prctl */
> +long set_tagged_addr_ctrl(unsigned long arg);
> +long get_tagged_addr_ctrl(void);
> +#define SET_TAGGED_ADDR_CTRL(arg)	set_tagged_addr_ctrl(arg)
> +#define GET_TAGGED_ADDR_CTRL()		get_tagged_addr_ctrl()
> +
>  /*
>   * For CONFIG_GCC_PLUGIN_STACKLEAK
>   *
> diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
> index c285d1ce7186..7263d4c973ce 100644
> --- a/arch/arm64/include/asm/thread_info.h
> +++ b/arch/arm64/include/asm/thread_info.h
> @@ -101,6 +101,7 @@ void arch_release_task_struct(struct task_struct *tsk);
>  #define TIF_SVE			23	/* Scalable Vector Extension in use */
>  #define TIF_SVE_VL_INHERIT	24	/* Inherit sve_vl_onexec across exec */
>  #define TIF_SSBD		25	/* Wants SSB mitigation */
> +#define TIF_TAGGED_ADDR		26
>

Can you please put a comment here?

>  #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
>  #define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
> diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
> index 9164ecb5feca..995b9ea11a89 100644
> --- a/arch/arm64/include/asm/uaccess.h
> +++ b/arch/arm64/include/asm/uaccess.h
> @@ -73,6 +73,9 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si
>  {
>  	unsigned long ret, limit = current_thread_info()->addr_limit;
>  
> +	if (test_thread_flag(TIF_TAGGED_ADDR))
> +		addr = untagged_addr(addr);
> +
>  	__chk_user_ptr(addr);
>  	asm volatile(
>  	// A + B <= C + 1 for all A,B,C, in four easy steps:
> @@ -94,7 +97,7 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si
>  	return ret;
>  }
>  
> -#define access_ok(addr, size)	__range_ok(untagged_addr(addr), size)
> +#define access_ok(addr, size)	__range_ok(addr, size)
>  #define user_addr_max			get_fs
>>  #define _ASM_EXTABLE(from, to)						\
> diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
> index 3767fb21a5b8..69d0be1fc708 100644
> --- a/arch/arm64/kernel/process.c
> +++ b/arch/arm64/kernel/process.c
> @@ -30,6 +30,7 @@
>  #include <linux/kernel.h>
>  #include <linux/mm.h>
>  #include <linux/stddef.h>
> +#include <linux/sysctl.h>
>  #include <linux/unistd.h>
>  #include <linux/user.h>
>  #include <linux/delay.h>
> @@ -323,6 +324,7 @@ void flush_thread(void)
>  	fpsimd_flush_thread();
>  	tls_thread_flush();
>  	flush_ptrace_hw_breakpoint(current);
> +	clear_thread_flag(TIF_TAGGED_ADDR);

Nit: in line we the other functions in thread_flush we could have something like
"tagged_addr_thread_flush", maybe inlined.

>  }
>  
>  void release_thread(struct task_struct *dead_task)
> @@ -552,3 +554,68 @@ void arch_setup_new_exec(void)
>  
>  	ptrauth_thread_init_user(current);
>  }
> +
> +/*
> + * Control the relaxed ABI allowing tagged user addresses into the kernel.
> + */
> +static unsigned int tagged_addr_prctl_allowed = 1;
> +
> +long set_tagged_addr_ctrl(unsigned long arg)
> +{
> +	if (!tagged_addr_prctl_allowed)
> +		return -EINVAL;
> +	if (is_compat_task())
> +		return -EINVAL;
> +	if (arg & ~PR_TAGGED_ADDR_ENABLE)
> +		return -EINVAL;
> +
> +	if (arg & PR_TAGGED_ADDR_ENABLE)
> +		set_thread_flag(TIF_TAGGED_ADDR);
> +	else
> +		clear_thread_flag(TIF_TAGGED_ADDR);
> +
> +	return 0;
> +}
> +
> +long get_tagged_addr_ctrl(void)
> +{
> +	if (!tagged_addr_prctl_allowed)
> +		return -EINVAL;
> +	if (is_compat_task())
> +		return -EINVAL;
> +
> +	if (test_thread_flag(TIF_TAGGED_ADDR))
> +		return PR_TAGGED_ADDR_ENABLE;
> +
> +	return 0;
> +}
> +
> +/*
> + * Global sysctl to disable the tagged user addresses support. This control
> + * only prevents the tagged address ABI enabling via prctl() and does not
> + * disable it for tasks that already opted in to the relaxed ABI.
> + */
> +static int zero;
> +static int one = 1;
> +
> +static struct ctl_table tagged_addr_sysctl_table[] = {
> +	{
> +		.procname	= "tagged_addr",
> +		.mode		= 0644,
> +		.data		= &tagged_addr_prctl_allowed,
> +		.maxlen		= sizeof(int),
> +		.proc_handler	= proc_dointvec_minmax,
> +		.extra1		= &zero,
> +		.extra2		= &one,
> +	},
> +	{ }
> +};
> +
> +static int __init tagged_addr_init(void)
> +{
> +	if (!register_sysctl("abi", tagged_addr_sysctl_table))
> +		return -EINVAL;
> +	return 0;
> +}
> +
> +core_initcall(tagged_addr_init);

process.c seems already a bit "overcrowded". Probably we could move all the
tagged_addr features in a separate file. What do you think? It would make easier
the implementation of mte as well going forward.

> diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h
> index 094bb03b9cc2..2e927b3e9d6c 100644
> --- a/include/uapi/linux/prctl.h
> +++ b/include/uapi/linux/prctl.h
> @@ -229,4 +229,9 @@ struct prctl_mm_map {
>  # define PR_PAC_APDBKEY			(1UL << 3)
>  # define PR_PAC_APGAKEY			(1UL << 4)
>  
> +/* Tagged user address controls for arm64 */
> +#define PR_SET_TAGGED_ADDR_CTRL		55
> +#define PR_GET_TAGGED_ADDR_CTRL		56
> +# define PR_TAGGED_ADDR_ENABLE		(1UL << 0)
> +
>  #endif /* _LINUX_PRCTL_H */
> diff --git a/kernel/sys.c b/kernel/sys.c
> index 2969304c29fe..ec48396b4943 100644
> --- a/kernel/sys.c
> +++ b/kernel/sys.c
> @@ -124,6 +124,12 @@
>  #ifndef PAC_RESET_KEYS
>  # define PAC_RESET_KEYS(a, b)	(-EINVAL)
>  #endif
> +#ifndef SET_TAGGED_ADDR_CTRL
> +# define SET_TAGGED_ADDR_CTRL(a)	(-EINVAL)
> +#endif
> +#ifndef GET_TAGGED_ADDR_CTRL
> +# define GET_TAGGED_ADDR_CTRL()		(-EINVAL)
> +#endif
>  
>  /*
>   * this is where the system-wide overflow UID and GID are defined, for
> @@ -2492,6 +2498,16 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
>  			return -EINVAL;
>  		error = PAC_RESET_KEYS(me, arg2);
>  		break;
> +	case PR_SET_TAGGED_ADDR_CTRL:
> +		if (arg3 || arg4 || arg5)
> +			return -EINVAL;
> +		error = SET_TAGGED_ADDR_CTRL(arg2);
> +		break;
> +	case PR_GET_TAGGED_ADDR_CTRL:
> +		if (arg2 || arg3 || arg4 || arg5)
> +			return -EINVAL;
> +		error = GET_TAGGED_ADDR_CTRL();
> +		break;

Why do we need two prctl here? We could have only one and use arg2 as set/get
and arg3 as a parameter. What do you think?

>  	default:
>  		error = -EINVAL;
>  		break;
> 

-- 
Regards,
Vincenzo

Re: [PATCH v16 02/16] arm64: untag user pointers in access_ok and __uaccess_mask_ptr

[Andrey Konovalov]

On Tue, Jun 11, 2019 at 4:57 PM Catalin Marinas <catalin.marinas@arm.com> wrote:
>
> On Mon, Jun 10, 2019 at 06:53:27PM +0100, Catalin Marinas wrote:
> > On Mon, Jun 03, 2019 at 06:55:04PM +0200, Andrey Konovalov wrote:
> > > diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
> > > index e5d5f31c6d36..9164ecb5feca 100644
> > > --- a/arch/arm64/include/asm/uaccess.h
> > > +++ b/arch/arm64/include/asm/uaccess.h
> > > @@ -94,7 +94,7 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si
> > >     return ret;
> > >  }
> > >
> > > -#define access_ok(addr, size)      __range_ok(addr, size)
> > > +#define access_ok(addr, size)      __range_ok(untagged_addr(addr), size)
> >
> > I'm going to propose an opt-in method here (RFC for now). We can't have
> > a check in untagged_addr() since this is already used throughout the
> > kernel for both user and kernel addresses (khwasan) but we can add one
> > in __range_ok(). The same prctl() option will be used for controlling
> > the precise/imprecise mode of MTE later on. We can use a TIF_ flag here
> > assuming that this will be called early on and any cloned thread will
> > inherit this.
>
> Updated patch, inlining it below. Once we agreed on the approach, I
> think Andrey can insert in in this series, probably after patch 2. The
> differences from the one I posted yesterday:
>
> - renamed PR_* macros together with get/set variants and the possibility
>   to disable the relaxed ABI
>
> - sysctl option - /proc/sys/abi/tagged_addr to disable the ABI globally
>   (just the prctl() opt-in, tasks already using it won't be affected)
>
> And, of course, it needs more testing.

Sure, I'll add it to the series.

Should I drop access_ok() change from my patch, since yours just reverts it?

Thanks!

>
> ---------8<----------------
> From 7c624777a4e545522dec1b34e60f0229cb2bd59f Mon Sep 17 00:00:00 2001
> From: Catalin Marinas <catalin.marinas@arm.com>
> Date: Tue, 11 Jun 2019 13:03:38 +0100
> Subject: [PATCH] arm64: Introduce prctl() options to control the tagged user
>  addresses ABI
>
> It is not desirable to relax the ABI to allow tagged user addresses into
> the kernel indiscriminately. This patch introduces a prctl() interface
> for enabling or disabling the tagged ABI with a global sysctl control
> for preventing applications from enabling the relaxed ABI (meant for
> testing user-space prctl() return error checking without reconfiguring
> the kernel). The ABI properties are inherited by threads of the same
> application and fork()'ed children but cleared on execve().
>
> The PR_SET_TAGGED_ADDR_CTRL will be expanded in the future to handle
> MTE-specific settings like imprecise vs precise exceptions.
>
> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
> ---
>  arch/arm64/include/asm/processor.h   |  6 +++
>  arch/arm64/include/asm/thread_info.h |  1 +
>  arch/arm64/include/asm/uaccess.h     |  5 ++-
>  arch/arm64/kernel/process.c          | 67 ++++++++++++++++++++++++++++
>  include/uapi/linux/prctl.h           |  5 +++
>  kernel/sys.c                         | 16 +++++++
>  6 files changed, 99 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
> index fcd0e691b1ea..fee457456aa8 100644
> --- a/arch/arm64/include/asm/processor.h
> +++ b/arch/arm64/include/asm/processor.h
> @@ -307,6 +307,12 @@ extern void __init minsigstksz_setup(void);
>  /* PR_PAC_RESET_KEYS prctl */
>  #define PAC_RESET_KEYS(tsk, arg)       ptrauth_prctl_reset_keys(tsk, arg)
>
> +/* PR_TAGGED_ADDR prctl */
> +long set_tagged_addr_ctrl(unsigned long arg);
> +long get_tagged_addr_ctrl(void);
> +#define SET_TAGGED_ADDR_CTRL(arg)      set_tagged_addr_ctrl(arg)
> +#define GET_TAGGED_ADDR_CTRL()         get_tagged_addr_ctrl()
> +
>  /*
>   * For CONFIG_GCC_PLUGIN_STACKLEAK
>   *
> diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
> index c285d1ce7186..7263d4c973ce 100644
> --- a/arch/arm64/include/asm/thread_info.h
> +++ b/arch/arm64/include/asm/thread_info.h
> @@ -101,6 +101,7 @@ void arch_release_task_struct(struct task_struct *tsk);
>  #define TIF_SVE                        23      /* Scalable Vector Extension in use */
>  #define TIF_SVE_VL_INHERIT     24      /* Inherit sve_vl_onexec across exec */
>  #define TIF_SSBD               25      /* Wants SSB mitigation */
> +#define TIF_TAGGED_ADDR                26
>
>  #define _TIF_SIGPENDING                (1 << TIF_SIGPENDING)
>  #define _TIF_NEED_RESCHED      (1 << TIF_NEED_RESCHED)
> diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
> index 9164ecb5feca..995b9ea11a89 100644
> --- a/arch/arm64/include/asm/uaccess.h
> +++ b/arch/arm64/include/asm/uaccess.h
> @@ -73,6 +73,9 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si
>  {
>         unsigned long ret, limit = current_thread_info()->addr_limit;
>
> +       if (test_thread_flag(TIF_TAGGED_ADDR))
> +               addr = untagged_addr(addr);
> +
>         __chk_user_ptr(addr);
>         asm volatile(
>         // A + B <= C + 1 for all A,B,C, in four easy steps:
> @@ -94,7 +97,7 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si
>         return ret;
>  }
>
> -#define access_ok(addr, size)  __range_ok(untagged_addr(addr), size)
> +#define access_ok(addr, size)  __range_ok(addr, size)
>  #define user_addr_max                  get_fs
>
>  #define _ASM_EXTABLE(from, to)                                         \
> diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
> index 3767fb21a5b8..69d0be1fc708 100644
> --- a/arch/arm64/kernel/process.c
> +++ b/arch/arm64/kernel/process.c
> @@ -30,6 +30,7 @@
>  #include <linux/kernel.h>
>  #include <linux/mm.h>
>  #include <linux/stddef.h>
> +#include <linux/sysctl.h>
>  #include <linux/unistd.h>
>  #include <linux/user.h>
>  #include <linux/delay.h>
> @@ -323,6 +324,7 @@ void flush_thread(void)
>         fpsimd_flush_thread();
>         tls_thread_flush();
>         flush_ptrace_hw_breakpoint(current);
> +       clear_thread_flag(TIF_TAGGED_ADDR);
>  }
>
>  void release_thread(struct task_struct *dead_task)
> @@ -552,3 +554,68 @@ void arch_setup_new_exec(void)
>
>         ptrauth_thread_init_user(current);
>  }
> +
> +/*
> + * Control the relaxed ABI allowing tagged user addresses into the kernel.
> + */
> +static unsigned int tagged_addr_prctl_allowed = 1;
> +
> +long set_tagged_addr_ctrl(unsigned long arg)
> +{
> +       if (!tagged_addr_prctl_allowed)
> +               return -EINVAL;
> +       if (is_compat_task())
> +               return -EINVAL;
> +       if (arg & ~PR_TAGGED_ADDR_ENABLE)
> +               return -EINVAL;
> +
> +       if (arg & PR_TAGGED_ADDR_ENABLE)
> +               set_thread_flag(TIF_TAGGED_ADDR);
> +       else
> +               clear_thread_flag(TIF_TAGGED_ADDR);
> +
> +       return 0;
> +}
> +
> +long get_tagged_addr_ctrl(void)
> +{
> +       if (!tagged_addr_prctl_allowed)
> +               return -EINVAL;
> +       if (is_compat_task())
> +               return -EINVAL;
> +
> +       if (test_thread_flag(TIF_TAGGED_ADDR))
> +               return PR_TAGGED_ADDR_ENABLE;
> +
> +       return 0;
> +}
> +
> +/*
> + * Global sysctl to disable the tagged user addresses support. This control
> + * only prevents the tagged address ABI enabling via prctl() and does not
> + * disable it for tasks that already opted in to the relaxed ABI.
> + */
> +static int zero;
> +static int one = 1;
> +
> +static struct ctl_table tagged_addr_sysctl_table[] = {
> +       {
> +               .procname       = "tagged_addr",
> +               .mode           = 0644,
> +               .data           = &tagged_addr_prctl_allowed,
> +               .maxlen         = sizeof(int),
> +               .proc_handler   = proc_dointvec_minmax,
> +               .extra1         = &zero,
> +               .extra2         = &one,
> +       },
> +       { }
> +};
> +
> +static int __init tagged_addr_init(void)
> +{
> +       if (!register_sysctl("abi", tagged_addr_sysctl_table))
> +               return -EINVAL;
> +       return 0;
> +}
> +
> +core_initcall(tagged_addr_init);
> diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h
> index 094bb03b9cc2..2e927b3e9d6c 100644
> --- a/include/uapi/linux/prctl.h
> +++ b/include/uapi/linux/prctl.h
> @@ -229,4 +229,9 @@ struct prctl_mm_map {
>  # define PR_PAC_APDBKEY                        (1UL << 3)
>  # define PR_PAC_APGAKEY                        (1UL << 4)
>
> +/* Tagged user address controls for arm64 */
> +#define PR_SET_TAGGED_ADDR_CTRL                55
> +#define PR_GET_TAGGED_ADDR_CTRL                56
> +# define PR_TAGGED_ADDR_ENABLE         (1UL << 0)
> +
>  #endif /* _LINUX_PRCTL_H */
> diff --git a/kernel/sys.c b/kernel/sys.c
> index 2969304c29fe..ec48396b4943 100644
> --- a/kernel/sys.c
> +++ b/kernel/sys.c
> @@ -124,6 +124,12 @@
>  #ifndef PAC_RESET_KEYS
>  # define PAC_RESET_KEYS(a, b)  (-EINVAL)
>  #endif
> +#ifndef SET_TAGGED_ADDR_CTRL
> +# define SET_TAGGED_ADDR_CTRL(a)       (-EINVAL)
> +#endif
> +#ifndef GET_TAGGED_ADDR_CTRL
> +# define GET_TAGGED_ADDR_CTRL()                (-EINVAL)
> +#endif
>
>  /*
>   * this is where the system-wide overflow UID and GID are defined, for
> @@ -2492,6 +2498,16 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
>                         return -EINVAL;
>                 error = PAC_RESET_KEYS(me, arg2);
>                 break;
> +       case PR_SET_TAGGED_ADDR_CTRL:
> +               if (arg3 || arg4 || arg5)
> +                       return -EINVAL;
> +               error = SET_TAGGED_ADDR_CTRL(arg2);
> +               break;
> +       case PR_GET_TAGGED_ADDR_CTRL:
> +               if (arg2 || arg3 || arg4 || arg5)
> +                       return -EINVAL;
> +               error = GET_TAGGED_ADDR_CTRL();
> +               break;
>         default:
>                 error = -EINVAL;
>                 break;

Re: [PATCH v16 16/16] selftests, arm64: add a selftest for passing tagged pointers to kernel

[Andrey Konovalov]

On Tue, Jun 11, 2019 at 5:01 PM Catalin Marinas <catalin.marinas@arm.com> wrote:
>
> On Mon, Jun 03, 2019 at 06:55:18PM +0200, Andrey Konovalov wrote:
> > This patch is a part of a series that extends arm64 kernel ABI to allow to
> > pass tagged user pointers (with the top byte set to something else other
> > than 0x00) as syscall arguments.
> >
> > This patch adds a simple test, that calls the uname syscall with a
> > tagged user pointer as an argument. Without the kernel accepting tagged
> > user pointers the test fails with EFAULT.
> >
> > Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
>
> BTW, you could add
>
> Co-developed-by: Catalin Marinas <catalin.marinas@arm.com>
>
> since I wrote the malloc() etc. hooks.

Sure!

>
>
> > +static void *tag_ptr(void *ptr)
> > +{
> > +     unsigned long tag = rand() & 0xff;
> > +     if (!ptr)
> > +             return ptr;
> > +     return (void *)((unsigned long)ptr | (tag << TAG_SHIFT));
> > +}
>
> With the prctl() option, this function becomes (if you have a better
> idea, fine by me):
>
> ----------8<---------------
> #include <stdlib.h>
> #include <sys/prctl.h>
>
> #define TAG_SHIFT       (56)
> #define TAG_MASK        (0xffUL << TAG_SHIFT)
>
> #define PR_SET_TAGGED_ADDR_CTRL         55
> #define PR_GET_TAGGED_ADDR_CTRL         56
> # define PR_TAGGED_ADDR_ENABLE          (1UL << 0)
>
> void *__libc_malloc(size_t size);
> void __libc_free(void *ptr);
> void *__libc_realloc(void *ptr, size_t size);
> void *__libc_calloc(size_t nmemb, size_t size);
>
> static void *tag_ptr(void *ptr)
> {
>         static int tagged_addr_err = 1;
>         unsigned long tag = 0;
>
>         if (tagged_addr_err == 1)
>                 tagged_addr_err = prctl(PR_SET_TAGGED_ADDR_CTRL,
>                                         PR_TAGGED_ADDR_ENABLE, 0, 0, 0);

I think this requires atomics. malloc() can be called from multiple threads.

>
>         if (!ptr)
>                 return ptr;
>         if (!tagged_addr_err)
>                 tag = rand() & 0xff;
>
>         return (void *)((unsigned long)ptr | (tag << TAG_SHIFT));
> }
>
> --
> Catalin

Re: [PATCH v16 02/16] arm64: untag user pointers in access_ok and __uaccess_mask_ptr

[Catalin Marinas]

On Tue, Jun 11, 2019 at 07:09:46PM +0200, Andrey Konovalov wrote:
> On Tue, Jun 11, 2019 at 4:57 PM Catalin Marinas <catalin.marinas@arm.com> wrote:
> >
> > On Mon, Jun 10, 2019 at 06:53:27PM +0100, Catalin Marinas wrote:
> > > On Mon, Jun 03, 2019 at 06:55:04PM +0200, Andrey Konovalov wrote:
> > > > diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
> > > > index e5d5f31c6d36..9164ecb5feca 100644
> > > > --- a/arch/arm64/include/asm/uaccess.h
> > > > +++ b/arch/arm64/include/asm/uaccess.h
> > > > @@ -94,7 +94,7 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si
> > > >     return ret;
> > > >  }
> > > >
> > > > -#define access_ok(addr, size)      __range_ok(addr, size)
> > > > +#define access_ok(addr, size)      __range_ok(untagged_addr(addr), size)
> > >
> > > I'm going to propose an opt-in method here (RFC for now). We can't have
> > > a check in untagged_addr() since this is already used throughout the
> > > kernel for both user and kernel addresses (khwasan) but we can add one
> > > in __range_ok(). The same prctl() option will be used for controlling
> > > the precise/imprecise mode of MTE later on. We can use a TIF_ flag here
> > > assuming that this will be called early on and any cloned thread will
> > > inherit this.
> >
> > Updated patch, inlining it below. Once we agreed on the approach, I
> > think Andrey can insert in in this series, probably after patch 2. The
> > differences from the one I posted yesterday:
> >
> > - renamed PR_* macros together with get/set variants and the possibility
> >   to disable the relaxed ABI
> >
> > - sysctl option - /proc/sys/abi/tagged_addr to disable the ABI globally
> >   (just the prctl() opt-in, tasks already using it won't be affected)
> >
> > And, of course, it needs more testing.
> 
> Sure, I'll add it to the series.
> 
> Should I drop access_ok() change from my patch, since yours just reverts it?

Not necessary, your patch just relaxes the ABI for all apps, mine
tightens it. You could instead move the untagging to __range_ok() and
rebase my patch accordingly.

-- 
Catalin

Re: [PATCH v16 05/16] arm64: untag user pointers passed to memory syscalls

[Catalin Marinas]

On Tue, Jun 11, 2019 at 05:35:31PM +0200, Andrey Konovalov wrote:
> On Mon, Jun 10, 2019 at 4:28 PM Catalin Marinas <catalin.marinas@arm.com> wrote:
> > On Mon, Jun 03, 2019 at 06:55:07PM +0200, Andrey Konovalov wrote:
> > > This patch is a part of a series that extends arm64 kernel ABI to allow to
> > > pass tagged user pointers (with the top byte set to something else other
> > > than 0x00) as syscall arguments.
> > >
> > > This patch allows tagged pointers to be passed to the following memory
> > > syscalls: get_mempolicy, madvise, mbind, mincore, mlock, mlock2, mprotect,
> > > mremap, msync, munlock.
> > >
> > > Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> >
> > I would add in the commit log (and possibly in the code with a comment)
> > that mremap() and mmap() do not currently accept tagged hint addresses.
> > Architectures may interpret the hint tag as a background colour for the
> > corresponding vma. With this:
> 
> I'll change the commit log. Where do you you think I should put this
> comment? Before mmap and mremap definitions in mm/?

On arm64 we use our own sys_mmap(). I'd say just add a comment on the
generic mremap() just before the untagged_addr() along the lines that
new_address is not untagged for preserving similar behaviour to mmap().

-- 
Catalin

Re: [PATCH v16 16/16] selftests, arm64: add a selftest for passing tagged pointers to kernel

[Catalin Marinas]

On Tue, Jun 11, 2019 at 07:18:04PM +0200, Andrey Konovalov wrote:
> On Tue, Jun 11, 2019 at 5:01 PM Catalin Marinas <catalin.marinas@arm.com> wrote:
> > static void *tag_ptr(void *ptr)
> > {
> >         static int tagged_addr_err = 1;
> >         unsigned long tag = 0;
> >
> >         if (tagged_addr_err == 1)
> >                 tagged_addr_err = prctl(PR_SET_TAGGED_ADDR_CTRL,
> >                                         PR_TAGGED_ADDR_ENABLE, 0, 0, 0);
> 
> I think this requires atomics. malloc() can be called from multiple threads.

It's slightly racy but I assume in a real libc it can be initialised
earlier than the hook calls while still in single-threaded mode (I had
a quick attempt with __attribute__((constructor)) but didn't get far).

Even with the race, under normal circumstances calling the prctl() twice
is not a problem. I think the risk here is that someone disables the ABI
via sysctl and the ABI is enabled for some of the threads only.

-- 
Catalin

Re: [PATCH v16 03/16] lib, arm64: untag user pointers in strn*_user

[Khalid Aziz]

On 6/3/19 10:55 AM, Andrey Konovalov wrote:
> This patch is a part of a series that extends arm64 kernel ABI to allow to
> pass tagged user pointers (with the top byte set to something else other
> than 0x00) as syscall arguments.
> 
> strncpy_from_user and strnlen_user accept user addresses as arguments, and
> do not go through the same path as copy_from_user and others, so here we
> need to handle the case of tagged user addresses separately.
> 
> Untag user pointers passed to these functions.
> 
> Note, that this patch only temporarily untags the pointers to perform
> validity checks, but then uses them as is to perform user memory accesses.
> 
> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> ---
>  lib/strncpy_from_user.c | 3 ++-
>  lib/strnlen_user.c      | 3 ++-
>  2 files changed, 4 insertions(+), 2 deletions(-)

Looks good.

Reviewed-by: Khalid Aziz <khalid.aziz@oracle.com>

> 
> diff --git a/lib/strncpy_from_user.c b/lib/strncpy_from_user.c
> index 023ba9f3b99f..dccb95af6003 100644
> --- a/lib/strncpy_from_user.c
> +++ b/lib/strncpy_from_user.c
> @@ -6,6 +6,7 @@
>  #include <linux/uaccess.h>
>  #include <linux/kernel.h>
>  #include <linux/errno.h>
> +#include <linux/mm.h>
>  
>  #include <asm/byteorder.h>
>  #include <asm/word-at-a-time.h>
> @@ -108,7 +109,7 @@ long strncpy_from_user(char *dst, const char __user *src, long count)
>  		return 0;
>  
>  	max_addr = user_addr_max();
> -	src_addr = (unsigned long)src;
> +	src_addr = (unsigned long)untagged_addr(src);
>  	if (likely(src_addr < max_addr)) {
>  		unsigned long max = max_addr - src_addr;
>  		long retval;
> diff --git a/lib/strnlen_user.c b/lib/strnlen_user.c
> index 7f2db3fe311f..28ff554a1be8 100644
> --- a/lib/strnlen_user.c
> +++ b/lib/strnlen_user.c
> @@ -2,6 +2,7 @@
>  #include <linux/kernel.h>
>  #include <linux/export.h>
>  #include <linux/uaccess.h>
> +#include <linux/mm.h>
>  
>  #include <asm/word-at-a-time.h>
>  
> @@ -109,7 +110,7 @@ long strnlen_user(const char __user *str, long count)
>  		return 0;
>  
>  	max_addr = user_addr_max();
> -	src_addr = (unsigned long)str;
> +	src_addr = (unsigned long)untagged_addr(str);
>  	if (likely(src_addr < max_addr)) {
>  		unsigned long max = max_addr - src_addr;
>  		long retval;
> 

Re: [PATCH v16 04/16] mm: untag user pointers in do_pages_move

[Khalid Aziz]

On 6/3/19 10:55 AM, Andrey Konovalov wrote:
> This patch is a part of a series that extends arm64 kernel ABI to allow to
> pass tagged user pointers (with the top byte set to something else other
> than 0x00) as syscall arguments.
> 
> do_pages_move() is used in the implementation of the move_pages syscall.
> 
> Untag user pointers in this function.
> 
> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> ---
>  mm/migrate.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/mm/migrate.c b/mm/migrate.c
> index f2ecc2855a12..3930bb6fa656 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1617,6 +1617,7 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
>  		if (get_user(node, nodes + i))
>  			goto out_flush;
>  		addr = (unsigned long)p;
> +		addr = untagged_addr(addr);

Why not just "addr = (unsigned long)untagged_addr(p);"

--
Khalid

Re: [PATCH v16 02/16] arm64: untag user pointers in access_ok and __uaccess_mask_ptr

[Catalin Marinas]

Hi Vincenzo,

On Tue, Jun 11, 2019 at 06:09:10PM +0100, Vincenzo Frascino wrote:
> > diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
> > index 3767fb21a5b8..69d0be1fc708 100644
> > --- a/arch/arm64/kernel/process.c
> > +++ b/arch/arm64/kernel/process.c
> > @@ -30,6 +30,7 @@
> >  #include <linux/kernel.h>
> >  #include <linux/mm.h>
> >  #include <linux/stddef.h>
> > +#include <linux/sysctl.h>
> >  #include <linux/unistd.h>
> >  #include <linux/user.h>
> >  #include <linux/delay.h>
> > @@ -323,6 +324,7 @@ void flush_thread(void)
> >  	fpsimd_flush_thread();
> >  	tls_thread_flush();
> >  	flush_ptrace_hw_breakpoint(current);
> > +	clear_thread_flag(TIF_TAGGED_ADDR);
> 
> Nit: in line we the other functions in thread_flush we could have something like
> "tagged_addr_thread_flush", maybe inlined.

The other functions do a lot more than clearing a TIF flag, so they
deserved their own place. We could do this when adding MTE support. I
think we also need to check what other TIF flags we may inadvertently
pass on execve(), maybe have a mask clearing.

> > diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h
> > index 094bb03b9cc2..2e927b3e9d6c 100644
> > --- a/include/uapi/linux/prctl.h
> > +++ b/include/uapi/linux/prctl.h
> > @@ -229,4 +229,9 @@ struct prctl_mm_map {
> >  # define PR_PAC_APDBKEY			(1UL << 3)
> >  # define PR_PAC_APGAKEY			(1UL << 4)
> >  
> > +/* Tagged user address controls for arm64 */
> > +#define PR_SET_TAGGED_ADDR_CTRL		55
> > +#define PR_GET_TAGGED_ADDR_CTRL		56
> > +# define PR_TAGGED_ADDR_ENABLE		(1UL << 0)
> > +
> >  #endif /* _LINUX_PRCTL_H */
> > diff --git a/kernel/sys.c b/kernel/sys.c
> > index 2969304c29fe..ec48396b4943 100644
> > --- a/kernel/sys.c
> > +++ b/kernel/sys.c
> > @@ -124,6 +124,12 @@
> >  #ifndef PAC_RESET_KEYS
> >  # define PAC_RESET_KEYS(a, b)	(-EINVAL)
> >  #endif
> > +#ifndef SET_TAGGED_ADDR_CTRL
> > +# define SET_TAGGED_ADDR_CTRL(a)	(-EINVAL)
> > +#endif
> > +#ifndef GET_TAGGED_ADDR_CTRL
> > +# define GET_TAGGED_ADDR_CTRL()		(-EINVAL)
> > +#endif
> >  
> >  /*
> >   * this is where the system-wide overflow UID and GID are defined, for
> > @@ -2492,6 +2498,16 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
> >  			return -EINVAL;
> >  		error = PAC_RESET_KEYS(me, arg2);
> >  		break;
> > +	case PR_SET_TAGGED_ADDR_CTRL:
> > +		if (arg3 || arg4 || arg5)
> > +			return -EINVAL;
> > +		error = SET_TAGGED_ADDR_CTRL(arg2);
> > +		break;
> > +	case PR_GET_TAGGED_ADDR_CTRL:
> > +		if (arg2 || arg3 || arg4 || arg5)
> > +			return -EINVAL;
> > +		error = GET_TAGGED_ADDR_CTRL();
> > +		break;
> 
> Why do we need two prctl here? We could have only one and use arg2 as set/get
> and arg3 as a parameter. What do you think?

This follows the other PR_* options, e.g. PR_SET_VL/GET_VL,
PR_*_FP_MODE. We will use other bits in arg2, for example to set the
precise vs imprecise MTE trapping.

-- 
Catalin

Re: [PATCH v16 15/16] vfio/type1, arm64: untag user pointers in vaddr_get_pfn

[Catalin Marinas]

On Mon, Jun 03, 2019 at 06:55:17PM +0200, Andrey Konovalov wrote:
> This patch is a part of a series that extends arm64 kernel ABI to allow to
> pass tagged user pointers (with the top byte set to something else other
> than 0x00) as syscall arguments.
> 
> vaddr_get_pfn() uses provided user pointers for vma lookups, which can
> only by done with untagged pointers.
> 
> Untag user pointers in this function.
> 
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>

Re: [PATCH v16 09/16] fs, arm64: untag user pointers in fs/userfaultfd.c

[Catalin Marinas]

On Mon, Jun 03, 2019 at 06:55:11PM +0200, Andrey Konovalov wrote:
> This patch is a part of a series that extends arm64 kernel ABI to allow to
> pass tagged user pointers (with the top byte set to something else other
> than 0x00) as syscall arguments.
> 
> userfaultfd code use provided user pointers for vma lookups, which can
> only by done with untagged pointers.
> 
> Untag user pointers in validate_range().
> 
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>

Re: [PATCH v16 12/16] IB, arm64: untag user pointers in ib_uverbs_(re)reg_mr()

[Catalin Marinas]

On Tue, Jun 04, 2019 at 03:09:26PM +0200, Andrey Konovalov wrote:
> On Tue, Jun 4, 2019 at 3:02 PM Jason Gunthorpe <jgg@ziepe.ca> wrote:
> > On Tue, Jun 04, 2019 at 02:45:32PM +0200, Andrey Konovalov wrote:
> > > On Tue, Jun 4, 2019 at 2:27 PM Jason Gunthorpe <jgg@ziepe.ca> wrote:
> > > > On Tue, Jun 04, 2019 at 02:18:19PM +0200, Andrey Konovalov wrote:
> > > > > On Mon, Jun 3, 2019 at 7:46 PM Jason Gunthorpe <jgg@ziepe.ca> wrote:
> > > > > > On Mon, Jun 03, 2019 at 06:55:14PM +0200, Andrey Konovalov wrote:
> > > > > > > This patch is a part of a series that extends arm64 kernel ABI to allow to
> > > > > > > pass tagged user pointers (with the top byte set to something else other
> > > > > > > than 0x00) as syscall arguments.
> > > > > > >
> > > > > > > ib_uverbs_(re)reg_mr() use provided user pointers for vma lookups (through
> > > > > > > e.g. mlx4_get_umem_mr()), which can only by done with untagged pointers.
> > > > > > >
> > > > > > > Untag user pointers in these functions.
> > > > > > >
> > > > > > > Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> > > > > > >  drivers/infiniband/core/uverbs_cmd.c | 4 ++++
> > > > > > >  1 file changed, 4 insertions(+)
> > > > > > >
> > > > > > > diff --git a/drivers/infiniband/core/uverbs_cmd.c b/drivers/infiniband/core/uverbs_cmd.c
> > > > > > > index 5a3a1780ceea..f88ee733e617 100644
> > > > > > > +++ b/drivers/infiniband/core/uverbs_cmd.c
> > > > > > > @@ -709,6 +709,8 @@ static int ib_uverbs_reg_mr(struct uverbs_attr_bundle *attrs)
> > > > > > >       if (ret)
> > > > > > >               return ret;
> > > > > > >
> > > > > > > +     cmd.start = untagged_addr(cmd.start);
> > > > > > > +
> > > > > > >       if ((cmd.start & ~PAGE_MASK) != (cmd.hca_va & ~PAGE_MASK))
> > > > > > >               return -EINVAL;
> > > > > >
> > > > > > I feel like we shouldn't thave to do this here, surely the cmd.start
> > > > > > should flow unmodified to get_user_pages, and gup should untag it?
> > > > > >
> > > > > > ie, this sort of direction for the IB code (this would be a giant
> > > > > > patch, so I didn't have time to write it all, but I think it is much
> > > > > > saner):
> > > > >
> > > > > ib_uverbs_reg_mr() passes cmd.start to mlx4_get_umem_mr(), which calls
> > > > > find_vma(), which only accepts untagged addresses. Could you explain
> > > > > how your patch helps?
> > > >
> > > > That mlx4 is just a 'weird duck', it is not the normal flow, and I
> > > > don't think the core code should be making special consideration for
> > > > it.
> > >
> > > How do you think we should do untagging (or something else) to deal
> > > with this 'weird duck' case?
> >
> > mlx4 should handle it around the call to find_vma like other patches
> > do, ideally as part of the cast from a void __user * to the unsigned
> > long that find_vma needs
> 
> So essentially what we had a few versions ago
> (https://lkml.org/lkml/2019/4/30/785) plus changing unsigned longs to
> __user * across all IB code? I think the second part is something
> that's not related to this series and needs to be done separately. I
> can move untagging back to mlx4_get_umem_mr() though.
> 
> Catalin, you've initially asked to to move untagging out of
> mlx4_get_umem_mr(), do you have any comments on this?

It's fine by me either way. My original reasoning was to untag this at
the higher level as tags may not be relevant to the mlx4 code. If that's
what Jason prefers, go for it.

-- 
Catalin

Re: [PATCH v16 02/16] arm64: untag user pointers in access_ok and __uaccess_mask_ptr

[Andrey Konovalov]

On Tue, Jun 11, 2019 at 7:39 PM Catalin Marinas <catalin.marinas@arm.com> wrote:
>
> On Tue, Jun 11, 2019 at 07:09:46PM +0200, Andrey Konovalov wrote:
> > On Tue, Jun 11, 2019 at 4:57 PM Catalin Marinas <catalin.marinas@arm.com> wrote:
> > >
> > > On Mon, Jun 10, 2019 at 06:53:27PM +0100, Catalin Marinas wrote:
> > > > On Mon, Jun 03, 2019 at 06:55:04PM +0200, Andrey Konovalov wrote:
> > > > > diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
> > > > > index e5d5f31c6d36..9164ecb5feca 100644
> > > > > --- a/arch/arm64/include/asm/uaccess.h
> > > > > +++ b/arch/arm64/include/asm/uaccess.h
> > > > > @@ -94,7 +94,7 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si
> > > > >     return ret;
> > > > >  }
> > > > >
> > > > > -#define access_ok(addr, size)      __range_ok(addr, size)
> > > > > +#define access_ok(addr, size)      __range_ok(untagged_addr(addr), size)
> > > >
> > > > I'm going to propose an opt-in method here (RFC for now). We can't have
> > > > a check in untagged_addr() since this is already used throughout the
> > > > kernel for both user and kernel addresses (khwasan) but we can add one
> > > > in __range_ok(). The same prctl() option will be used for controlling
> > > > the precise/imprecise mode of MTE later on. We can use a TIF_ flag here
> > > > assuming that this will be called early on and any cloned thread will
> > > > inherit this.
> > >
> > > Updated patch, inlining it below. Once we agreed on the approach, I
> > > think Andrey can insert in in this series, probably after patch 2. The
> > > differences from the one I posted yesterday:
> > >
> > > - renamed PR_* macros together with get/set variants and the possibility
> > >   to disable the relaxed ABI
> > >
> > > - sysctl option - /proc/sys/abi/tagged_addr to disable the ABI globally
> > >   (just the prctl() opt-in, tasks already using it won't be affected)
> > >
> > > And, of course, it needs more testing.
> >
> > Sure, I'll add it to the series.
> >
> > Should I drop access_ok() change from my patch, since yours just reverts it?
>
> Not necessary, your patch just relaxes the ABI for all apps, mine
> tightens it. You could instead move the untagging to __range_ok() and
> rebase my patch accordingly.

OK, will do. I'll also add a comment next to TIF_TAGGED_ADDR as Vincenzo asked.

>
> --
> Catalin

Re: [PATCH v16 02/16] arm64: untag user pointers in access_ok and __uaccess_mask_ptr

[Catalin Marinas]

On Wed, Jun 12, 2019 at 01:03:10PM +0200, Andrey Konovalov wrote:
> On Tue, Jun 11, 2019 at 7:39 PM Catalin Marinas <catalin.marinas@arm.com> wrote:
> > On Tue, Jun 11, 2019 at 07:09:46PM +0200, Andrey Konovalov wrote:
> > > Should I drop access_ok() change from my patch, since yours just reverts it?
> >
> > Not necessary, your patch just relaxes the ABI for all apps, mine
> > tightens it. You could instead move the untagging to __range_ok() and
> > rebase my patch accordingly.
> 
> OK, will do. I'll also add a comment next to TIF_TAGGED_ADDR as Vincenzo asked.

Thanks.

-- 
Catalin

Re: [PATCH v16 04/16] mm: untag user pointers in do_pages_move

[Andrey Konovalov]

On Tue, Jun 11, 2019 at 10:18 PM Khalid Aziz <khalid.aziz@oracle.com> wrote:
>
> On 6/3/19 10:55 AM, Andrey Konovalov wrote:
> > This patch is a part of a series that extends arm64 kernel ABI to allow to
> > pass tagged user pointers (with the top byte set to something else other
> > than 0x00) as syscall arguments.
> >
> > do_pages_move() is used in the implementation of the move_pages syscall.
> >
> > Untag user pointers in this function.
> >
> > Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
> > Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> > ---
> >  mm/migrate.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/mm/migrate.c b/mm/migrate.c
> > index f2ecc2855a12..3930bb6fa656 100644
> > --- a/mm/migrate.c
> > +++ b/mm/migrate.c
> > @@ -1617,6 +1617,7 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
> >               if (get_user(node, nodes + i))
> >                       goto out_flush;
> >               addr = (unsigned long)p;
> > +             addr = untagged_addr(addr);
>
> Why not just "addr = (unsigned long)untagged_addr(p);"

Will do in the next version. I think I'll also merge this commit into
the "untag user pointers passed to memory syscalls" one.

>
> --
> Khalid
>

Re: [PATCH v16 05/16] arm64: untag user pointers passed to memory syscalls

[Andrey Konovalov]

On Tue, Jun 11, 2019 at 7:45 PM Catalin Marinas <catalin.marinas@arm.com> wrote:
>
> On Tue, Jun 11, 2019 at 05:35:31PM +0200, Andrey Konovalov wrote:
> > On Mon, Jun 10, 2019 at 4:28 PM Catalin Marinas <catalin.marinas@arm.com> wrote:
> > > On Mon, Jun 03, 2019 at 06:55:07PM +0200, Andrey Konovalov wrote:
> > > > This patch is a part of a series that extends arm64 kernel ABI to allow to
> > > > pass tagged user pointers (with the top byte set to something else other
> > > > than 0x00) as syscall arguments.
> > > >
> > > > This patch allows tagged pointers to be passed to the following memory
> > > > syscalls: get_mempolicy, madvise, mbind, mincore, mlock, mlock2, mprotect,
> > > > mremap, msync, munlock.
> > > >
> > > > Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> > >
> > > I would add in the commit log (and possibly in the code with a comment)
> > > that mremap() and mmap() do not currently accept tagged hint addresses.
> > > Architectures may interpret the hint tag as a background colour for the
> > > corresponding vma. With this:
> >
> > I'll change the commit log. Where do you you think I should put this
> > comment? Before mmap and mremap definitions in mm/?
>
> On arm64 we use our own sys_mmap(). I'd say just add a comment on the
> generic mremap() just before the untagged_addr() along the lines that
> new_address is not untagged for preserving similar behaviour to mmap().

Will do in v17, thanks!

>
> --
> Catalin

Re: [PATCH v16 16/16] selftests, arm64: add a selftest for passing tagged pointers to kernel

[Andrey Konovalov]

On Tue, Jun 11, 2019 at 7:50 PM Catalin Marinas <catalin.marinas@arm.com> wrote:
>
> On Tue, Jun 11, 2019 at 07:18:04PM +0200, Andrey Konovalov wrote:
> > On Tue, Jun 11, 2019 at 5:01 PM Catalin Marinas <catalin.marinas@arm.com> wrote:
> > > static void *tag_ptr(void *ptr)
> > > {
> > >         static int tagged_addr_err = 1;
> > >         unsigned long tag = 0;
> > >
> > >         if (tagged_addr_err == 1)
> > >                 tagged_addr_err = prctl(PR_SET_TAGGED_ADDR_CTRL,
> > >                                         PR_TAGGED_ADDR_ENABLE, 0, 0, 0);
> >
> > I think this requires atomics. malloc() can be called from multiple threads.
>
> It's slightly racy but I assume in a real libc it can be initialised
> earlier than the hook calls while still in single-threaded mode (I had
> a quick attempt with __attribute__((constructor)) but didn't get far).
>
> Even with the race, under normal circumstances calling the prctl() twice
> is not a problem. I think the risk here is that someone disables the ABI
> via sysctl and the ABI is enabled for some of the threads only.

OK, I'll keep the code racy, but add a comment pointing it out. Thanks!

>
> --
> Catalin

Re: [PATCH v16 08/16] fs, arm64: untag user pointers in copy_mount_options

[Andrey Konovalov]

On Tue, Jun 11, 2019 at 4:38 PM Andrey Konovalov <andreyknvl@google.com> wrote:
>
> On Sat, Jun 8, 2019 at 6:02 AM Kees Cook <keescook@chromium.org> wrote:
> >
> > On Mon, Jun 03, 2019 at 06:55:10PM +0200, Andrey Konovalov wrote:
> > > This patch is a part of a series that extends arm64 kernel ABI to allow to
> > > pass tagged user pointers (with the top byte set to something else other
> > > than 0x00) as syscall arguments.
> > >
> > > In copy_mount_options a user address is being subtracted from TASK_SIZE.
> > > If the address is lower than TASK_SIZE, the size is calculated to not
> > > allow the exact_copy_from_user() call to cross TASK_SIZE boundary.
> > > However if the address is tagged, then the size will be calculated
> > > incorrectly.
> > >
> > > Untag the address before subtracting.
> > >
> > > Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
> > > Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> >
> > One thing I just noticed in the commit titles... "arm64" is in the
> > prefix, but these are arch-indep areas. Should the ", arm64" be left
> > out?
> >
> > I would expect, instead:
> >
> >         fs/namespace: untag user pointers in copy_mount_options
>
> Hm, I've added the arm64 tag in all of the patches because they are
> related to changes in arm64 kernel ABI. I can remove it from all the
> patches that only touch common code if you think that it makes sense.

I'll keep the arm64 tags in commit titles for v17. Please reply
explicitly if you think I should remove them. Thanks! :)

>
> Thanks!
>
> >
> > Reviewed-by: Kees Cook <keescook@chromium.org>
> >
> > -Kees
> >
> > > ---
> > >  fs/namespace.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/fs/namespace.c b/fs/namespace.c
> > > index b26778bdc236..2e85712a19ed 100644
> > > --- a/fs/namespace.c
> > > +++ b/fs/namespace.c
> > > @@ -2993,7 +2993,7 @@ void *copy_mount_options(const void __user * data)
> > >        * the remainder of the page.
> > >        */
> > >       /* copy_from_user cannot cross TASK_SIZE ! */
> > > -     size = TASK_SIZE - (unsigned long)data;
> > > +     size = TASK_SIZE - (unsigned long)untagged_addr(data);
> > >       if (size > PAGE_SIZE)
> > >               size = PAGE_SIZE;
> > >
> > > --
> > > 2.22.0.rc1.311.g5d7573a151-goog
> > >
> >
> > --
> > Kees Cook

Re: [PATCH v16 02/16] arm64: untag user pointers in access_ok and __uaccess_mask_ptr

[Vincenzo Frascino]

Hi Catalin,

On 12/06/2019 10:32, Catalin Marinas wrote:
> Hi Vincenzo,
> 
> On Tue, Jun 11, 2019 at 06:09:10PM +0100, Vincenzo Frascino wrote:
>>> diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
>>> index 3767fb21a5b8..69d0be1fc708 100644
>>> --- a/arch/arm64/kernel/process.c
>>> +++ b/arch/arm64/kernel/process.c
>>> @@ -30,6 +30,7 @@
>>>  #include <linux/kernel.h>
>>>  #include <linux/mm.h>
>>>  #include <linux/stddef.h>
>>> +#include <linux/sysctl.h>
>>>  #include <linux/unistd.h>
>>>  #include <linux/user.h>
>>>  #include <linux/delay.h>
>>> @@ -323,6 +324,7 @@ void flush_thread(void)
>>>  	fpsimd_flush_thread();
>>>  	tls_thread_flush();
>>>  	flush_ptrace_hw_breakpoint(current);
>>> +	clear_thread_flag(TIF_TAGGED_ADDR);
>>
>> Nit: in line we the other functions in thread_flush we could have something like
>> "tagged_addr_thread_flush", maybe inlined.
> 
> The other functions do a lot more than clearing a TIF flag, so they
> deserved their own place. We could do this when adding MTE support. I
> think we also need to check what other TIF flags we may inadvertently
> pass on execve(), maybe have a mask clearing.
> 

Agreed. All the comments I provided are meant to simplify the addition of MTE
support.

>>> diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h
>>> index 094bb03b9cc2..2e927b3e9d6c 100644
>>> --- a/include/uapi/linux/prctl.h
>>> +++ b/include/uapi/linux/prctl.h
>>> @@ -229,4 +229,9 @@ struct prctl_mm_map {
>>>  # define PR_PAC_APDBKEY			(1UL << 3)
>>>  # define PR_PAC_APGAKEY			(1UL << 4)
>>>  
>>> +/* Tagged user address controls for arm64 */
>>> +#define PR_SET_TAGGED_ADDR_CTRL		55
>>> +#define PR_GET_TAGGED_ADDR_CTRL		56
>>> +# define PR_TAGGED_ADDR_ENABLE		(1UL << 0)
>>> +
>>>  #endif /* _LINUX_PRCTL_H */
>>> diff --git a/kernel/sys.c b/kernel/sys.c
>>> index 2969304c29fe..ec48396b4943 100644
>>> --- a/kernel/sys.c
>>> +++ b/kernel/sys.c
>>> @@ -124,6 +124,12 @@
>>>  #ifndef PAC_RESET_KEYS
>>>  # define PAC_RESET_KEYS(a, b)	(-EINVAL)
>>>  #endif
>>> +#ifndef SET_TAGGED_ADDR_CTRL
>>> +# define SET_TAGGED_ADDR_CTRL(a)	(-EINVAL)
>>> +#endif
>>> +#ifndef GET_TAGGED_ADDR_CTRL
>>> +# define GET_TAGGED_ADDR_CTRL()		(-EINVAL)
>>> +#endif
>>>  
>>>  /*
>>>   * this is where the system-wide overflow UID and GID are defined, for
>>> @@ -2492,6 +2498,16 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
>>>  			return -EINVAL;
>>>  		error = PAC_RESET_KEYS(me, arg2);
>>>  		break;
>>> +	case PR_SET_TAGGED_ADDR_CTRL:
>>> +		if (arg3 || arg4 || arg5)
>>> +			return -EINVAL;
>>> +		error = SET_TAGGED_ADDR_CTRL(arg2);
>>> +		break;
>>> +	case PR_GET_TAGGED_ADDR_CTRL:
>>> +		if (arg2 || arg3 || arg4 || arg5)
>>> +			return -EINVAL;
>>> +		error = GET_TAGGED_ADDR_CTRL();
>>> +		break;
>>
>> Why do we need two prctl here? We could have only one and use arg2 as set/get
>> and arg3 as a parameter. What do you think?
> 
> This follows the other PR_* options, e.g. PR_SET_VL/GET_VL,
> PR_*_FP_MODE. We will use other bits in arg2, for example to set the
> precise vs imprecise MTE trapping.
> 

Indeed. I was not questioning the pre-existing interface definition, but trying
more to reduce the changes to the ABI to the minimum since:
 - prctl does not mandate how to use the arg[2-5]
 - prctl interface is flexible enough for the problem to be solved with only one
   PR_ command.

I agree on reusing the interface for MTE for the purposes you specified.

-- 
Regards,
Vincenzo