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* [PATCH v7 0/7] mm: introduce memfd_secret system call to create "secret" memory areas
@ 2020-10-26  8:37 Mike Rapoport
  2020-10-26  8:37 ` [PATCH v7 1/7] mm: add definition of PMD_PAGE_ORDER Mike Rapoport
                   ` (6 more replies)
  0 siblings, 7 replies; 12+ messages in thread
From: Mike Rapoport @ 2020-10-26  8:37 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Alexander Viro, Andy Lutomirski, Arnd Bergmann, Borislav Petkov,
	Catalin Marinas, Christopher Lameter, Dan Williams, Dave Hansen,
	David Hildenbrand, Elena Reshetova, H. Peter Anvin, Ingo Molnar,
	James Bottomley, Kirill A. Shutemov, Matthew Wilcox,
	Mark Rutland, Mike Rapoport, Mike Rapoport, Michael Kerrisk,
	Palmer Dabbelt, Paul Walmsley, Peter Zijlstra, Rick Edgecombe,
	Shuah Khan, Thomas Gleixner, Tycho Andersen, Will Deacon,
	linux-api, linux-arch, linux-arm-kernel, linux-fsdevel, linux-mm,
	linux-kernel, linux-kselftest, linux-nvdimm, linux-riscv, x86

From: Mike Rapoport <rppt@linux.ibm.com>

Hi,

This is an implementation of "secret" mappings backed by a file descriptor.

The file descriptor backing secret memory mappings is created using a
dedicated memfd_secret system call The desired protection mode for the
memory is configured using flags parameter of the system call. The mmap()
of the file descriptor created with memfd_secret() will create a "secret"
memory mapping. The pages in that mapping will be marked as not present in
the direct map and will have desired protection bits set in the user page
table. For instance, current implementation allows uncached mappings.

Although normally Linux userspace mappings are protected from other users,
such secret mappings are useful for environments where a hostile tenant is
trying to trick the kernel into giving them access to other tenants
mappings.

Additionally, in the future the secret mappings may be used as a mean to
protect guest memory in a virtual machine host.

For demonstration of secret memory usage we've created a userspace library

https://git.kernel.org/pub/scm/linux/kernel/git/jejb/secret-memory-preloader.git

that does two things: the first is act as a preloader for openssl to
redirect all the OPENSSL_malloc calls to secret memory meaning any secret
keys get automatically protected this way and the other thing it does is
expose the API to the user who needs it. We anticipate that a lot of the
use cases would be like the openssl one: many toolkits that deal with
secret keys already have special handling for the memory to try to give
them greater protection, so this would simply be pluggable into the
toolkits without any need for user application modification.

Hiding secret memory mappings behind an anonymous file allows (ab)use of
the page cache for tracking pages allocated for the "secret" mappings as
well as using address_space_operations for e.g. page migration callbacks.

The anonymous file may be also used implicitly, like hugetlb files, to
implement mmap(MAP_SECRET) and use the secret memory areas with "native" mm
ABIs in the future.

To limit fragmentation of the direct map to splitting only PUD-size pages,
I've added an amortizing cache of PMD-size pages to each file descriptor
that is used as an allocation pool for the secret memory areas.

It is easy to add boot time reservation of the memory for secretmem
needs. There was an implementation in earlier version of this set, but I've
dropped it for now as there is no consensus whether the boot time
reservation should be done from memblock or from CMA. I beleive we can have
this discussion after straightening out the basic implementation.

v7:
* Use set_direct_map() instead of __kernel_map_pages() to ensure error
  handling in case the direct map update fails
* Add accounting of large pages used to reduce the direct map fragmentation
* Teach get_user_pages() and frieds to refuse get/pin secretmem pages

v6: https://lore.kernel.org/lkml/20200924132904.1391-1-rppt@kernel.org
* Silence the warning about missing syscall, thanks to Qian Cai
* Replace spaces with tabs in Kconfig additions, per Randy
* Add a selftest.

v5: https://lore.kernel.org/lkml/20200916073539.3552-1-rppt@kernel.org
* rebase on v5.9-rc5
* drop boot time memory reservation patch

v4: https://lore.kernel.org/lkml/20200818141554.13945-1-rppt@kernel.org
* rebase on v5.9-rc1
* Do not redefine PMD_PAGE_ORDER in fs/dax.c, thanks Kirill
* Make secret mappings exclusive by default and only require flags to
  memfd_secret() system call for uncached mappings, thanks again Kirill :)

v3: https://lore.kernel.org/lkml/20200804095035.18778-1-rppt@kernel.org
* Squash kernel-parameters.txt update into the commit that added the
  command line option.
* Make uncached mode explicitly selectable by architectures. For now enable
  it only on x86.

v2: https://lore.kernel.org/lkml/20200727162935.31714-1-rppt@kernel.org
* Follow Michael's suggestion and name the new system call 'memfd_secret'
* Add kernel-parameters documentation about the boot option
* Fix i386-tinyconfig regression reported by the kbuild bot.
  CONFIG_SECRETMEM now depends on !EMBEDDED to disable it on small systems
  from one side and still make it available unconditionally on
  architectures that support SET_DIRECT_MAP.

v1: https://lore.kernel.org/lkml/20200720092435.17469-1-rppt@kernel.org

Mike Rapoport (8):
  mm: add definition of PMD_PAGE_ORDER
  mmap: make mlock_future_check() global
  set_memory: allow set_direct_map_*_noflush() for multiple pages
  mm: introduce memfd_secret system call to create "secret" memory areas
  arch, mm: wire up memfd_secret system call were relevant
  mm: secretmem: use PMD-size pages to amortize direct map fragmentation
  secretmem: test: add basic selftest for memfd_secret(2)
  mm: secretmem: add ability to reserve memory at boot

 arch/Kconfig                              |   7 +
 arch/arm64/include/asm/cacheflush.h       |   4 +-
 arch/arm64/include/asm/unistd.h           |   2 +-
 arch/arm64/include/asm/unistd32.h         |   2 +
 arch/arm64/include/uapi/asm/unistd.h      |   1 +
 arch/arm64/mm/pageattr.c                  |  10 +-
 arch/riscv/include/asm/set_memory.h       |   4 +-
 arch/riscv/include/asm/unistd.h           |   1 +
 arch/riscv/mm/pageattr.c                  |   8 +-
 arch/x86/Kconfig                          |   1 +
 arch/x86/entry/syscalls/syscall_32.tbl    |   1 +
 arch/x86/entry/syscalls/syscall_64.tbl    |   1 +
 arch/x86/include/asm/set_memory.h         |   4 +-
 arch/x86/mm/pat/set_memory.c              |   8 +-
 fs/dax.c                                  |  11 +-
 include/linux/pgtable.h                   |   3 +
 include/linux/set_memory.h                |   4 +-
 include/linux/syscalls.h                  |   1 +
 include/uapi/asm-generic/unistd.h         |   7 +-
 include/uapi/linux/magic.h                |   1 +
 include/uapi/linux/secretmem.h            |   8 +
 kernel/sys_ni.c                           |   2 +
 mm/Kconfig                                |   4 +
 mm/Makefile                               |   1 +
 mm/gup.c                                  |  10 +
 mm/internal.h                             |   3 +
 mm/mmap.c                                 |   5 +-
 mm/secretmem.c                            | 487 ++++++++++++++++++++++
 mm/vmalloc.c                              |   5 +-
 scripts/checksyscalls.sh                  |   4 +
 tools/testing/selftests/vm/.gitignore     |   1 +
 tools/testing/selftests/vm/Makefile       |   3 +-
 tools/testing/selftests/vm/memfd_secret.c | 296 +++++++++++++
 tools/testing/selftests/vm/run_vmtests    |  17 +
 34 files changed, 892 insertions(+), 35 deletions(-)
 create mode 100644 include/uapi/linux/secretmem.h
 create mode 100644 mm/secretmem.c
 create mode 100644 tools/testing/selftests/vm/memfd_secret.c

--
2.28.0

^ permalink raw reply	[flat|nested] 12+ messages in thread

* [PATCH v7 1/7] mm: add definition of PMD_PAGE_ORDER
  2020-10-26  8:37 [PATCH v7 0/7] mm: introduce memfd_secret system call to create "secret" memory areas Mike Rapoport
@ 2020-10-26  8:37 ` Mike Rapoport
  2020-10-27  8:26   ` David Hildenbrand
  2020-10-26  8:37 ` [PATCH v7 2/7] mmap: make mlock_future_check() global Mike Rapoport
                   ` (5 subsequent siblings)
  6 siblings, 1 reply; 12+ messages in thread
From: Mike Rapoport @ 2020-10-26  8:37 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Alexander Viro, Andy Lutomirski, Arnd Bergmann, Borislav Petkov,
	Catalin Marinas, Christopher Lameter, Dan Williams, Dave Hansen,
	David Hildenbrand, Elena Reshetova, H. Peter Anvin, Ingo Molnar,
	James Bottomley, Kirill A. Shutemov, Matthew Wilcox,
	Mark Rutland, Mike Rapoport, Mike Rapoport, Michael Kerrisk,
	Palmer Dabbelt, Paul Walmsley, Peter Zijlstra, Rick Edgecombe,
	Shuah Khan, Thomas Gleixner, Tycho Andersen, Will Deacon,
	linux-api, linux-arch, linux-arm-kernel, linux-fsdevel, linux-mm,
	linux-kernel, linux-kselftest, linux-nvdimm, linux-riscv, x86

From: Mike Rapoport <rppt@linux.ibm.com>

The definition of PMD_PAGE_ORDER denoting the number of base pages in the
second-level leaf page is already used by DAX and maybe handy in other
cases as well.

Several architectures already have definition of PMD_ORDER as the size of
second level page table, so to avoid conflict with these definitions use
PMD_PAGE_ORDER name and update DAX respectively.

Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
---
 fs/dax.c                | 11 ++++-------
 include/linux/pgtable.h |  3 +++
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 5b47834f2e1b..de3dbcaa849a 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -49,9 +49,6 @@ static inline unsigned int pe_order(enum page_entry_size pe_size)
 #define PG_PMD_COLOUR	((PMD_SIZE >> PAGE_SHIFT) - 1)
 #define PG_PMD_NR	(PMD_SIZE >> PAGE_SHIFT)
 
-/* The order of a PMD entry */
-#define PMD_ORDER	(PMD_SHIFT - PAGE_SHIFT)
-
 static wait_queue_head_t wait_table[DAX_WAIT_TABLE_ENTRIES];
 
 static int __init init_dax_wait_table(void)
@@ -98,7 +95,7 @@ static bool dax_is_locked(void *entry)
 static unsigned int dax_entry_order(void *entry)
 {
 	if (xa_to_value(entry) & DAX_PMD)
-		return PMD_ORDER;
+		return PMD_PAGE_ORDER;
 	return 0;
 }
 
@@ -1471,7 +1468,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
 {
 	struct vm_area_struct *vma = vmf->vma;
 	struct address_space *mapping = vma->vm_file->f_mapping;
-	XA_STATE_ORDER(xas, &mapping->i_pages, vmf->pgoff, PMD_ORDER);
+	XA_STATE_ORDER(xas, &mapping->i_pages, vmf->pgoff, PMD_PAGE_ORDER);
 	unsigned long pmd_addr = vmf->address & PMD_MASK;
 	bool write = vmf->flags & FAULT_FLAG_WRITE;
 	bool sync;
@@ -1530,7 +1527,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
 	 * entry is already in the array, for instance), it will return
 	 * VM_FAULT_FALLBACK.
 	 */
-	entry = grab_mapping_entry(&xas, mapping, PMD_ORDER);
+	entry = grab_mapping_entry(&xas, mapping, PMD_PAGE_ORDER);
 	if (xa_is_internal(entry)) {
 		result = xa_to_internal(entry);
 		goto fallback;
@@ -1696,7 +1693,7 @@ dax_insert_pfn_mkwrite(struct vm_fault *vmf, pfn_t pfn, unsigned int order)
 	if (order == 0)
 		ret = vmf_insert_mixed_mkwrite(vmf->vma, vmf->address, pfn);
 #ifdef CONFIG_FS_DAX_PMD
-	else if (order == PMD_ORDER)
+	else if (order == PMD_PAGE_ORDER)
 		ret = vmf_insert_pfn_pmd(vmf, pfn, FAULT_FLAG_WRITE);
 #endif
 	else
diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index 38c33eabea89..bd0617fe066e 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -28,6 +28,9 @@
 #define USER_PGTABLES_CEILING	0UL
 #endif
 
+/* Number of base pages in a second level leaf page */
+#define PMD_PAGE_ORDER	(PMD_SHIFT - PAGE_SHIFT)
+
 /*
  * A page table page can be thought of an array like this: pXd_t[PTRS_PER_PxD]
  *
-- 
2.28.0


^ permalink raw reply	[flat|nested] 12+ messages in thread

* [PATCH v7 2/7] mmap: make mlock_future_check() global
  2020-10-26  8:37 [PATCH v7 0/7] mm: introduce memfd_secret system call to create "secret" memory areas Mike Rapoport
  2020-10-26  8:37 ` [PATCH v7 1/7] mm: add definition of PMD_PAGE_ORDER Mike Rapoport
@ 2020-10-26  8:37 ` Mike Rapoport
  2020-10-26  8:37 ` [PATCH v7 3/7] set_memory: allow set_direct_map_*_noflush() for multiple pages Mike Rapoport
                   ` (4 subsequent siblings)
  6 siblings, 0 replies; 12+ messages in thread
From: Mike Rapoport @ 2020-10-26  8:37 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Alexander Viro, Andy Lutomirski, Arnd Bergmann, Borislav Petkov,
	Catalin Marinas, Christopher Lameter, Dan Williams, Dave Hansen,
	David Hildenbrand, Elena Reshetova, H. Peter Anvin, Ingo Molnar,
	James Bottomley, Kirill A. Shutemov, Matthew Wilcox,
	Mark Rutland, Mike Rapoport, Mike Rapoport, Michael Kerrisk,
	Palmer Dabbelt, Paul Walmsley, Peter Zijlstra, Rick Edgecombe,
	Shuah Khan, Thomas Gleixner, Tycho Andersen, Will Deacon,
	linux-api, linux-arch, linux-arm-kernel, linux-fsdevel, linux-mm,
	linux-kernel, linux-kselftest, linux-nvdimm, linux-riscv, x86

From: Mike Rapoport <rppt@linux.ibm.com>

It will be used by the upcoming secret memory implementation.

Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
---
 mm/internal.h | 3 +++
 mm/mmap.c     | 5 ++---
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/mm/internal.h b/mm/internal.h
index c43ccdddb0f6..ae146a260b14 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -348,6 +348,9 @@ static inline void munlock_vma_pages_all(struct vm_area_struct *vma)
 extern void mlock_vma_page(struct page *page);
 extern unsigned int munlock_vma_page(struct page *page);
 
+extern int mlock_future_check(struct mm_struct *mm, unsigned long flags,
+			      unsigned long len);
+
 /*
  * Clear the page's PageMlocked().  This can be useful in a situation where
  * we want to unconditionally remove a page from the pagecache -- e.g.,
diff --git a/mm/mmap.c b/mm/mmap.c
index d91ecb00d38c..d166ad427882 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1348,9 +1348,8 @@ static inline unsigned long round_hint_to_min(unsigned long hint)
 	return hint;
 }
 
-static inline int mlock_future_check(struct mm_struct *mm,
-				     unsigned long flags,
-				     unsigned long len)
+int mlock_future_check(struct mm_struct *mm, unsigned long flags,
+		       unsigned long len)
 {
 	unsigned long locked, lock_limit;
 
-- 
2.28.0


^ permalink raw reply	[flat|nested] 12+ messages in thread

* [PATCH v7 3/7] set_memory: allow set_direct_map_*_noflush() for multiple pages
  2020-10-26  8:37 [PATCH v7 0/7] mm: introduce memfd_secret system call to create "secret" memory areas Mike Rapoport
  2020-10-26  8:37 ` [PATCH v7 1/7] mm: add definition of PMD_PAGE_ORDER Mike Rapoport
  2020-10-26  8:37 ` [PATCH v7 2/7] mmap: make mlock_future_check() global Mike Rapoport
@ 2020-10-26  8:37 ` Mike Rapoport
  2020-10-26 19:01   ` Edgecombe, Rick P
  2020-10-26  8:37 ` [PATCH v7 4/7] mm: introduce memfd_secret system call to create "secret" memory areas Mike Rapoport
                   ` (3 subsequent siblings)
  6 siblings, 1 reply; 12+ messages in thread
From: Mike Rapoport @ 2020-10-26  8:37 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Alexander Viro, Andy Lutomirski, Arnd Bergmann, Borislav Petkov,
	Catalin Marinas, Christopher Lameter, Dan Williams, Dave Hansen,
	David Hildenbrand, Elena Reshetova, H. Peter Anvin, Ingo Molnar,
	James Bottomley, Kirill A. Shutemov, Matthew Wilcox,
	Mark Rutland, Mike Rapoport, Mike Rapoport, Michael Kerrisk,
	Palmer Dabbelt, Paul Walmsley, Peter Zijlstra, Rick Edgecombe,
	Shuah Khan, Thomas Gleixner, Tycho Andersen, Will Deacon,
	linux-api, linux-arch, linux-arm-kernel, linux-fsdevel, linux-mm,
	linux-kernel, linux-kselftest, linux-nvdimm, linux-riscv, x86

From: Mike Rapoport <rppt@linux.ibm.com>

The underlying implementations of set_direct_map_invalid_noflush() and
set_direct_map_default_noflush() allow updating multiple contiguous pages
at once.

Add numpages parameter to set_direct_map_*_noflush() to expose this ability
with these APIs.

Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
---
 arch/arm64/include/asm/cacheflush.h |  4 ++--
 arch/arm64/mm/pageattr.c            | 10 ++++++----
 arch/riscv/include/asm/set_memory.h |  4 ++--
 arch/riscv/mm/pageattr.c            |  8 ++++----
 arch/x86/include/asm/set_memory.h   |  4 ++--
 arch/x86/mm/pat/set_memory.c        |  8 ++++----
 include/linux/set_memory.h          |  4 ++--
 mm/vmalloc.c                        |  5 +++--
 8 files changed, 25 insertions(+), 22 deletions(-)

diff --git a/arch/arm64/include/asm/cacheflush.h b/arch/arm64/include/asm/cacheflush.h
index 9384fd8fc13c..831739bc93a6 100644
--- a/arch/arm64/include/asm/cacheflush.h
+++ b/arch/arm64/include/asm/cacheflush.h
@@ -138,8 +138,8 @@ static __always_inline void __flush_icache_all(void)
 
 int set_memory_valid(unsigned long addr, int numpages, int enable);
 
-int set_direct_map_invalid_noflush(struct page *page);
-int set_direct_map_default_noflush(struct page *page);
+int set_direct_map_invalid_noflush(struct page *page, int numpages);
+int set_direct_map_default_noflush(struct page *page, int numpages);
 
 #include <asm-generic/cacheflush.h>
 
diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c
index 1b94f5b82654..2d4e8c4cdab5 100644
--- a/arch/arm64/mm/pageattr.c
+++ b/arch/arm64/mm/pageattr.c
@@ -148,34 +148,36 @@ int set_memory_valid(unsigned long addr, int numpages, int enable)
 					__pgprot(PTE_VALID));
 }
 
-int set_direct_map_invalid_noflush(struct page *page)
+int set_direct_map_invalid_noflush(struct page *page, int numpages)
 {
 	struct page_change_data data = {
 		.set_mask = __pgprot(0),
 		.clear_mask = __pgprot(PTE_VALID),
 	};
+	unsigned long size = PAGE_SIZE * numpages;
 
 	if (!rodata_full)
 		return 0;
 
 	return apply_to_page_range(&init_mm,
 				   (unsigned long)page_address(page),
-				   PAGE_SIZE, change_page_range, &data);
+				   size, change_page_range, &data);
 }
 
-int set_direct_map_default_noflush(struct page *page)
+int set_direct_map_default_noflush(struct page *page, int numpages)
 {
 	struct page_change_data data = {
 		.set_mask = __pgprot(PTE_VALID | PTE_WRITE),
 		.clear_mask = __pgprot(PTE_RDONLY),
 	};
+	unsigned long size = PAGE_SIZE * numpages;
 
 	if (!rodata_full)
 		return 0;
 
 	return apply_to_page_range(&init_mm,
 				   (unsigned long)page_address(page),
-				   PAGE_SIZE, change_page_range, &data);
+				   size, change_page_range, &data);
 }
 
 void __kernel_map_pages(struct page *page, int numpages, int enable)
diff --git a/arch/riscv/include/asm/set_memory.h b/arch/riscv/include/asm/set_memory.h
index 4c5bae7ca01c..e20f1bef9b11 100644
--- a/arch/riscv/include/asm/set_memory.h
+++ b/arch/riscv/include/asm/set_memory.h
@@ -22,8 +22,8 @@ static inline int set_memory_x(unsigned long addr, int numpages) { return 0; }
 static inline int set_memory_nx(unsigned long addr, int numpages) { return 0; }
 #endif
 
-int set_direct_map_invalid_noflush(struct page *page);
-int set_direct_map_default_noflush(struct page *page);
+int set_direct_map_invalid_noflush(struct page *page, int numpages);
+int set_direct_map_default_noflush(struct page *page, int numpages);
 
 #endif /* __ASSEMBLY__ */
 
diff --git a/arch/riscv/mm/pageattr.c b/arch/riscv/mm/pageattr.c
index 19fecb362d81..58743bb6b755 100644
--- a/arch/riscv/mm/pageattr.c
+++ b/arch/riscv/mm/pageattr.c
@@ -150,11 +150,11 @@ int set_memory_nx(unsigned long addr, int numpages)
 	return __set_memory(addr, numpages, __pgprot(0), __pgprot(_PAGE_EXEC));
 }
 
-int set_direct_map_invalid_noflush(struct page *page)
+int set_direct_map_invalid_noflush(struct page *page, int numpages)
 {
 	int ret;
 	unsigned long start = (unsigned long)page_address(page);
-	unsigned long end = start + PAGE_SIZE;
+	unsigned long end = start + PAGE_SIZE * numpages;
 	struct pageattr_masks masks = {
 		.set_mask = __pgprot(0),
 		.clear_mask = __pgprot(_PAGE_PRESENT)
@@ -167,11 +167,11 @@ int set_direct_map_invalid_noflush(struct page *page)
 	return ret;
 }
 
-int set_direct_map_default_noflush(struct page *page)
+int set_direct_map_default_noflush(struct page *page, int numpages)
 {
 	int ret;
 	unsigned long start = (unsigned long)page_address(page);
-	unsigned long end = start + PAGE_SIZE;
+	unsigned long end = start + PAGE_SIZE * numpages;
 	struct pageattr_masks masks = {
 		.set_mask = PAGE_KERNEL,
 		.clear_mask = __pgprot(0)
diff --git a/arch/x86/include/asm/set_memory.h b/arch/x86/include/asm/set_memory.h
index 5948218f35c5..2c5fb6b338e7 100644
--- a/arch/x86/include/asm/set_memory.h
+++ b/arch/x86/include/asm/set_memory.h
@@ -80,8 +80,8 @@ int set_pages_wb(struct page *page, int numpages);
 int set_pages_ro(struct page *page, int numpages);
 int set_pages_rw(struct page *page, int numpages);
 
-int set_direct_map_invalid_noflush(struct page *page);
-int set_direct_map_default_noflush(struct page *page);
+int set_direct_map_invalid_noflush(struct page *page, int numpages);
+int set_direct_map_default_noflush(struct page *page, int numpages);
 
 extern int kernel_set_to_readonly;
 
diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c
index 40baa90e74f4..239bdddf6f96 100644
--- a/arch/x86/mm/pat/set_memory.c
+++ b/arch/x86/mm/pat/set_memory.c
@@ -2184,14 +2184,14 @@ static int __set_pages_np(struct page *page, int numpages)
 	return __change_page_attr_set_clr(&cpa, 0);
 }
 
-int set_direct_map_invalid_noflush(struct page *page)
+int set_direct_map_invalid_noflush(struct page *page, int numpages)
 {
-	return __set_pages_np(page, 1);
+	return __set_pages_np(page, numpages);
 }
 
-int set_direct_map_default_noflush(struct page *page)
+int set_direct_map_default_noflush(struct page *page, int numpages)
 {
-	return __set_pages_p(page, 1);
+	return __set_pages_p(page, numpages);
 }
 
 void __kernel_map_pages(struct page *page, int numpages, int enable)
diff --git a/include/linux/set_memory.h b/include/linux/set_memory.h
index 860e0f843c12..a938a3775082 100644
--- a/include/linux/set_memory.h
+++ b/include/linux/set_memory.h
@@ -15,11 +15,11 @@ static inline int set_memory_nx(unsigned long addr, int numpages) { return 0; }
 #endif
 
 #ifndef CONFIG_ARCH_HAS_SET_DIRECT_MAP
-static inline int set_direct_map_invalid_noflush(struct page *page)
+static inline int set_direct_map_invalid_noflush(struct page *page, int numpages)
 {
 	return 0;
 }
-static inline int set_direct_map_default_noflush(struct page *page)
+static inline int set_direct_map_default_noflush(struct page *page, int numpages)
 {
 	return 0;
 }
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 6ae491a8b210..670fc20ad44c 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2179,13 +2179,14 @@ struct vm_struct *remove_vm_area(const void *addr)
 }
 
 static inline void set_area_direct_map(const struct vm_struct *area,
-				       int (*set_direct_map)(struct page *page))
+				       int (*set_direct_map)(struct page *page,
+							     int numpages))
 {
 	int i;
 
 	for (i = 0; i < area->nr_pages; i++)
 		if (page_address(area->pages[i]))
-			set_direct_map(area->pages[i]);
+			set_direct_map(area->pages[i], 1);
 }
 
 /* Handle removing and resetting vm mappings related to the vm_struct. */
-- 
2.28.0


^ permalink raw reply	[flat|nested] 12+ messages in thread

* [PATCH v7 4/7] mm: introduce memfd_secret system call to create "secret" memory areas
  2020-10-26  8:37 [PATCH v7 0/7] mm: introduce memfd_secret system call to create "secret" memory areas Mike Rapoport
                   ` (2 preceding siblings ...)
  2020-10-26  8:37 ` [PATCH v7 3/7] set_memory: allow set_direct_map_*_noflush() for multiple pages Mike Rapoport
@ 2020-10-26  8:37 ` Mike Rapoport
  2020-10-26  8:37 ` [PATCH v7 5/7] arch, mm: wire up memfd_secret system call were relevant Mike Rapoport
                   ` (2 subsequent siblings)
  6 siblings, 0 replies; 12+ messages in thread
From: Mike Rapoport @ 2020-10-26  8:37 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Alexander Viro, Andy Lutomirski, Arnd Bergmann, Borislav Petkov,
	Catalin Marinas, Christopher Lameter, Dan Williams, Dave Hansen,
	David Hildenbrand, Elena Reshetova, H. Peter Anvin, Ingo Molnar,
	James Bottomley, Kirill A. Shutemov, Matthew Wilcox,
	Mark Rutland, Mike Rapoport, Mike Rapoport, Michael Kerrisk,
	Palmer Dabbelt, Paul Walmsley, Peter Zijlstra, Rick Edgecombe,
	Shuah Khan, Thomas Gleixner, Tycho Andersen, Will Deacon,
	linux-api, linux-arch, linux-arm-kernel, linux-fsdevel, linux-mm,
	linux-kernel, linux-kselftest, linux-nvdimm, linux-riscv, x86

From: Mike Rapoport <rppt@linux.ibm.com>

Introduce "memfd_secret" system call with the ability to create memory
areas visible only in the context of the owning process and not mapped not
only to other processes but in the kernel page tables as well.

The user will create a file descriptor using the memfd_secret() system call
where flags supplied as a parameter to this system call will define the
desired protection mode for the memory associated with that file
descriptor.

The secret memory remains accessible in the process context using uaccess
primitives, but it is not accessible using direct/linear map addresses.

Functions in the follow_page()/get_user_page() family will refuse to return
a page that belongs to the secret memory area.

 Currently there are two protection modes:

* exclusive - the memory area is unmapped from the kernel direct map and it
              is present only in the page tables of the owning mm.
* uncached  - the memory area is present only in the page tables of the
              owning mm and it is mapped there as uncached.

The "exclusive" mode is enabled implicitly and it is the default mode for
memfd_secret().

The "uncached" mode requires architecture support and an architecture
should opt-in for this mode using HAVE_SECRETMEM_UNCACHED configuration
option.

For instance, the following example will create an uncached mapping (error
handling is omitted):

	fd = memfd_secret(SECRETMEM_UNCACHED);
	ftruncate(fd, MAP_SIZE);
	ptr = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);

Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
---
 arch/Kconfig                   |   7 +
 arch/x86/Kconfig               |   1 +
 include/uapi/linux/magic.h     |   1 +
 include/uapi/linux/secretmem.h |   8 +
 kernel/sys_ni.c                |   2 +
 mm/Kconfig                     |   4 +
 mm/Makefile                    |   1 +
 mm/gup.c                       |  10 ++
 mm/secretmem.c                 | 279 +++++++++++++++++++++++++++++++++
 9 files changed, 313 insertions(+)
 create mode 100644 include/uapi/linux/secretmem.h
 create mode 100644 mm/secretmem.c

diff --git a/arch/Kconfig b/arch/Kconfig
index 56b6ccc0e32d..3da5727fe403 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -1028,6 +1028,13 @@ config HAVE_STATIC_CALL_INLINE
 	bool
 	depends on HAVE_STATIC_CALL
 
+config HAVE_SECRETMEM_UNCACHED
+	bool
+	help
+	  An architecture can select this if its semantics of non-cached
+	  mappings can be used to prevent speculative loads and it is
+	  useful for secret protection.
+
 source "kernel/gcov/Kconfig"
 
 source "scripts/gcc-plugins/Kconfig"
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index f6946b81f74a..8aca235f338b 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -222,6 +222,7 @@ config X86
 	select HAVE_UNSTABLE_SCHED_CLOCK
 	select HAVE_USER_RETURN_NOTIFIER
 	select HAVE_GENERIC_VDSO
+	select HAVE_SECRETMEM_UNCACHED
 	select HOTPLUG_SMT			if SMP
 	select IRQ_FORCED_THREADING
 	select NEED_SG_DMA_LENGTH
diff --git a/include/uapi/linux/magic.h b/include/uapi/linux/magic.h
index f3956fc11de6..35687dcb1a42 100644
--- a/include/uapi/linux/magic.h
+++ b/include/uapi/linux/magic.h
@@ -97,5 +97,6 @@
 #define DEVMEM_MAGIC		0x454d444d	/* "DMEM" */
 #define Z3FOLD_MAGIC		0x33
 #define PPC_CMM_MAGIC		0xc7571590
+#define SECRETMEM_MAGIC		0x5345434d	/* "SECM" */
 
 #endif /* __LINUX_MAGIC_H__ */
diff --git a/include/uapi/linux/secretmem.h b/include/uapi/linux/secretmem.h
new file mode 100644
index 000000000000..7cf9492c70d2
--- /dev/null
+++ b/include/uapi/linux/secretmem.h
@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _UAPI_LINUX_SECRETMEM_H
+#define _UAPI_LINUX_SECRETMEM_H
+
+/* secretmem operation modes */
+#define SECRETMEM_UNCACHED	0x1
+
+#endif /* _UAPI_LINUX_SECRETMEM_H */
diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
index f27ac94d5fa7..3cb8a45879cc 100644
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.c
@@ -350,6 +350,8 @@ COND_SYSCALL(pkey_mprotect);
 COND_SYSCALL(pkey_alloc);
 COND_SYSCALL(pkey_free);
 
+/* memfd_secret */
+COND_SYSCALL(memfd_secret);
 
 /*
  * Architecture specific weak syscall entries.
diff --git a/mm/Kconfig b/mm/Kconfig
index d42423f884a7..a0f278d13eb5 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -872,4 +872,8 @@ config ARCH_HAS_HUGEPD
 config MAPPING_DIRTY_HELPERS
         bool
 
+config SECRETMEM
+	def_bool ARCH_HAS_SET_DIRECT_MAP && !EMBEDDED
+	select GENERIC_ALLOCATOR
+
 endmenu
diff --git a/mm/Makefile b/mm/Makefile
index d73aed0fc99c..8d3ffbc372b1 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -120,3 +120,4 @@ obj-$(CONFIG_MEMFD_CREATE) += memfd.o
 obj-$(CONFIG_MAPPING_DIRTY_HELPERS) += mapping_dirty_helpers.o
 obj-$(CONFIG_PTDUMP_CORE) += ptdump.o
 obj-$(CONFIG_PAGE_REPORTING) += page_reporting.o
+obj-$(CONFIG_SECRETMEM) += secretmem.o
diff --git a/mm/gup.c b/mm/gup.c
index 102877ed77a4..92b43c838d45 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -10,6 +10,7 @@
 #include <linux/rmap.h>
 #include <linux/swap.h>
 #include <linux/swapops.h>
+#include <linux/secretmem.h>
 
 #include <linux/sched/signal.h>
 #include <linux/rwsem.h>
@@ -793,6 +794,9 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
 	struct follow_page_context ctx = { NULL };
 	struct page *page;
 
+	if (vma_is_secretmem(vma))
+		return NULL;
+
 	page = follow_page_mask(vma, address, foll_flags, &ctx);
 	if (ctx.pgmap)
 		put_dev_pagemap(ctx.pgmap);
@@ -923,6 +927,9 @@ static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags)
 	if (gup_flags & FOLL_ANON && !vma_is_anonymous(vma))
 		return -EFAULT;
 
+	if (vma_is_secretmem(vma))
+		return -EFAULT;
+
 	if (write) {
 		if (!(vm_flags & VM_WRITE)) {
 			if (!(gup_flags & FOLL_FORCE))
@@ -2188,6 +2195,9 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
 		VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
 		page = pte_page(pte);
 
+		if (page_is_secretmem(page))
+			goto pte_unmap;
+
 		head = try_grab_compound_head(page, 1, flags);
 		if (!head)
 			goto pte_unmap;
diff --git a/mm/secretmem.c b/mm/secretmem.c
new file mode 100644
index 000000000000..2a63db2ed132
--- /dev/null
+++ b/mm/secretmem.c
@@ -0,0 +1,279 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright IBM Corporation, 2020
+ *
+ * Author: Mike Rapoport <rppt@linux.ibm.com>
+ */
+
+#include <linux/mm.h>
+#include <linux/fs.h>
+#include <linux/mount.h>
+#include <linux/memfd.h>
+#include <linux/bitops.h>
+#include <linux/printk.h>
+#include <linux/pagemap.h>
+#include <linux/syscalls.h>
+#include <linux/pseudo_fs.h>
+#include <linux/set_memory.h>
+#include <linux/sched/signal.h>
+
+#include <uapi/linux/secretmem.h>
+#include <uapi/linux/magic.h>
+
+#include <asm/tlbflush.h>
+
+#include "internal.h"
+
+#undef pr_fmt
+#define pr_fmt(fmt) "secretmem: " fmt
+
+/*
+ * Secret memory areas are always exclusive to owning mm and they are
+ * removed from the direct map.
+ */
+#ifdef CONFIG_HAVE_SECRETMEM_UNCACHED
+#define SECRETMEM_MODE_MASK	(SECRETMEM_UNCACHED)
+#else
+#define SECRETMEM_MODE_MASK	(0x0)
+#endif
+
+#define SECRETMEM_FLAGS_MASK	SECRETMEM_MODE_MASK
+
+struct secretmem_ctx {
+	unsigned int mode;
+};
+
+static struct page *secretmem_alloc_page(gfp_t gfp)
+{
+	/*
+	 * FIXME: use a cache of large pages to reduce the direct map
+	 * fragmentation
+	 */
+	return alloc_page(gfp);
+}
+
+static vm_fault_t secretmem_fault(struct vm_fault *vmf)
+{
+	struct address_space *mapping = vmf->vma->vm_file->f_mapping;
+	struct inode *inode = file_inode(vmf->vma->vm_file);
+	pgoff_t offset = vmf->pgoff;
+	unsigned long addr;
+	struct page *page;
+	int ret = 0;
+
+	if (((loff_t)vmf->pgoff << PAGE_SHIFT) >= i_size_read(inode))
+		return vmf_error(-EINVAL);
+
+	page = find_get_entry(mapping, offset);
+	if (!page) {
+		page = secretmem_alloc_page(vmf->gfp_mask);
+		if (!page)
+			return vmf_error(-ENOMEM);
+
+		ret = add_to_page_cache(page, mapping, offset, vmf->gfp_mask);
+		if (unlikely(ret))
+			goto err_put_page;
+
+		ret = set_direct_map_invalid_noflush(page, 1);
+		if (ret)
+			goto err_del_page_cache;
+
+		addr = (unsigned long)page_address(page);
+		flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
+
+		__SetPageUptodate(page);
+
+		ret = VM_FAULT_LOCKED;
+	}
+
+	vmf->page = page;
+	return ret;
+
+err_del_page_cache:
+	delete_from_page_cache(page);
+err_put_page:
+	put_page(page);
+	return vmf_error(ret);
+}
+
+static const struct vm_operations_struct secretmem_vm_ops = {
+	.fault = secretmem_fault,
+};
+
+static int secretmem_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	struct secretmem_ctx *ctx = file->private_data;
+	unsigned long len = vma->vm_end - vma->vm_start;
+
+	if ((vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) == 0)
+		return -EINVAL;
+
+	if (mlock_future_check(vma->vm_mm, vma->vm_flags | VM_LOCKED, len))
+		return -EAGAIN;
+
+	if (ctx->mode & SECRETMEM_UNCACHED)
+		vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+
+	vma->vm_ops = &secretmem_vm_ops;
+	vma->vm_flags |= VM_LOCKED;
+
+	return 0;
+}
+
+bool vma_is_secretmem(struct vm_area_struct *vma)
+{
+	return vma->vm_ops == &secretmem_vm_ops;
+}
+
+const struct file_operations secretmem_fops = {
+	.mmap		= secretmem_mmap,
+};
+
+static bool secretmem_isolate_page(struct page *page, isolate_mode_t mode)
+{
+	return false;
+}
+
+static int secretmem_migratepage(struct address_space *mapping,
+				 struct page *newpage, struct page *page,
+				 enum migrate_mode mode)
+{
+	return -EBUSY;
+}
+
+static void secretmem_freepage(struct page *page)
+{
+	set_direct_map_default_noflush(page, 1);
+}
+
+static const struct address_space_operations secretmem_aops = {
+	.freepage	= secretmem_freepage,
+	.migratepage	= secretmem_migratepage,
+	.isolate_page	= secretmem_isolate_page,
+};
+
+bool page_is_secretmem(struct page *page)
+{
+	struct address_space *mapping = page_mapping(page);
+
+	if (!mapping)
+		return false;
+
+	return mapping->a_ops == &secretmem_aops;
+}
+
+static struct vfsmount *secretmem_mnt;
+
+static struct file *secretmem_file_create(unsigned long flags)
+{
+	struct file *file = ERR_PTR(-ENOMEM);
+	struct secretmem_ctx *ctx;
+	struct inode *inode;
+
+	inode = alloc_anon_inode(secretmem_mnt->mnt_sb);
+	if (IS_ERR(inode))
+		return ERR_CAST(inode);
+
+	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
+	if (!ctx)
+		goto err_free_inode;
+
+	file = alloc_file_pseudo(inode, secretmem_mnt, "secretmem",
+				 O_RDWR, &secretmem_fops);
+	if (IS_ERR(file))
+		goto err_free_ctx;
+
+	mapping_set_unevictable(inode->i_mapping);
+
+	inode->i_mapping->private_data = ctx;
+	inode->i_mapping->a_ops = &secretmem_aops;
+
+	/* pretend we are a normal file with zero size */
+	inode->i_mode |= S_IFREG;
+	inode->i_size = 0;
+
+	file->private_data = ctx;
+
+	ctx->mode = flags & SECRETMEM_MODE_MASK;
+
+	return file;
+
+err_free_ctx:
+	kfree(ctx);
+err_free_inode:
+	iput(inode);
+	return file;
+}
+
+SYSCALL_DEFINE1(memfd_secret, unsigned long, flags)
+{
+	struct file *file;
+	int fd, err;
+
+	/* make sure local flags do not confict with global fcntl.h */
+	BUILD_BUG_ON(SECRETMEM_FLAGS_MASK & O_CLOEXEC);
+
+	if (flags & ~(SECRETMEM_FLAGS_MASK | O_CLOEXEC))
+		return -EINVAL;
+
+	fd = get_unused_fd_flags(flags & O_CLOEXEC);
+	if (fd < 0)
+		return fd;
+
+	file = secretmem_file_create(flags);
+	if (IS_ERR(file)) {
+		err = PTR_ERR(file);
+		goto err_put_fd;
+	}
+
+	file->f_flags |= O_LARGEFILE;
+
+	fd_install(fd, file);
+	return fd;
+
+err_put_fd:
+	put_unused_fd(fd);
+	return err;
+}
+
+static void secretmem_evict_inode(struct inode *inode)
+{
+	struct secretmem_ctx *ctx = inode->i_private;
+
+	truncate_inode_pages_final(&inode->i_data);
+	clear_inode(inode);
+	kfree(ctx);
+}
+
+static const struct super_operations secretmem_super_ops = {
+	.evict_inode = secretmem_evict_inode,
+};
+
+static int secretmem_init_fs_context(struct fs_context *fc)
+{
+	struct pseudo_fs_context *ctx = init_pseudo(fc, SECRETMEM_MAGIC);
+
+	if (!ctx)
+		return -ENOMEM;
+	ctx->ops = &secretmem_super_ops;
+
+	return 0;
+}
+
+static struct file_system_type secretmem_fs = {
+	.name		= "secretmem",
+	.init_fs_context = secretmem_init_fs_context,
+	.kill_sb	= kill_anon_super,
+};
+
+static int secretmem_init(void)
+{
+	int ret = 0;
+
+	secretmem_mnt = kern_mount(&secretmem_fs);
+	if (IS_ERR(secretmem_mnt))
+		ret = PTR_ERR(secretmem_mnt);
+
+	return ret;
+}
+fs_initcall(secretmem_init);
-- 
2.28.0


^ permalink raw reply	[flat|nested] 12+ messages in thread

* [PATCH v7 5/7] arch, mm: wire up memfd_secret system call were relevant
  2020-10-26  8:37 [PATCH v7 0/7] mm: introduce memfd_secret system call to create "secret" memory areas Mike Rapoport
                   ` (3 preceding siblings ...)
  2020-10-26  8:37 ` [PATCH v7 4/7] mm: introduce memfd_secret system call to create "secret" memory areas Mike Rapoport
@ 2020-10-26  8:37 ` Mike Rapoport
  2020-10-26  8:37 ` [PATCH v7 6/7] mm: secretmem: use PMD-size pages to amortize direct map fragmentation Mike Rapoport
  2020-10-26  8:37 ` [PATCH v7 7/7] secretmem: test: add basic selftest for memfd_secret(2) Mike Rapoport
  6 siblings, 0 replies; 12+ messages in thread
From: Mike Rapoport @ 2020-10-26  8:37 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Alexander Viro, Andy Lutomirski, Arnd Bergmann, Borislav Petkov,
	Catalin Marinas, Christopher Lameter, Dan Williams, Dave Hansen,
	David Hildenbrand, Elena Reshetova, H. Peter Anvin, Ingo Molnar,
	James Bottomley, Kirill A. Shutemov, Matthew Wilcox,
	Mark Rutland, Mike Rapoport, Mike Rapoport, Michael Kerrisk,
	Palmer Dabbelt, Paul Walmsley, Peter Zijlstra, Rick Edgecombe,
	Shuah Khan, Thomas Gleixner, Tycho Andersen, Will Deacon,
	linux-api, linux-arch, linux-arm-kernel, linux-fsdevel, linux-mm,
	linux-kernel, linux-kselftest, linux-nvdimm, linux-riscv, x86,
	Palmer Dabbelt

From: Mike Rapoport <rppt@linux.ibm.com>

Wire up memfd_secret system call on architectures that define
ARCH_HAS_SET_DIRECT_MAP, namely arm64, risc-v and x86.

Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Palmer Dabbelt <palmerdabbelt@google.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
---
 arch/arm64/include/asm/unistd.h        | 2 +-
 arch/arm64/include/asm/unistd32.h      | 2 ++
 arch/arm64/include/uapi/asm/unistd.h   | 1 +
 arch/riscv/include/asm/unistd.h        | 1 +
 arch/x86/entry/syscalls/syscall_32.tbl | 1 +
 arch/x86/entry/syscalls/syscall_64.tbl | 1 +
 include/linux/syscalls.h               | 1 +
 include/uapi/asm-generic/unistd.h      | 7 ++++++-
 scripts/checksyscalls.sh               | 4 ++++
 9 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/unistd.h b/arch/arm64/include/asm/unistd.h
index b3b2019f8d16..86a9d7b3eabe 100644
--- a/arch/arm64/include/asm/unistd.h
+++ b/arch/arm64/include/asm/unistd.h
@@ -38,7 +38,7 @@
 #define __ARM_NR_compat_set_tls		(__ARM_NR_COMPAT_BASE + 5)
 #define __ARM_NR_COMPAT_END		(__ARM_NR_COMPAT_BASE + 0x800)
 
-#define __NR_compat_syscalls		441
+#define __NR_compat_syscalls		442
 #endif
 
 #define __ARCH_WANT_SYS_CLONE
diff --git a/arch/arm64/include/asm/unistd32.h b/arch/arm64/include/asm/unistd32.h
index 107f08e03b9f..e40ed72322de 100644
--- a/arch/arm64/include/asm/unistd32.h
+++ b/arch/arm64/include/asm/unistd32.h
@@ -889,6 +889,8 @@ __SYSCALL(__NR_pidfd_getfd, sys_pidfd_getfd)
 __SYSCALL(__NR_faccessat2, sys_faccessat2)
 #define __NR_process_madvise 440
 __SYSCALL(__NR_process_madvise, sys_process_madvise)
+#define __NR_memfd_secret 441
+__SYSCALL(__NR_memfd_secret, sys_memfd_secret)
 
 /*
  * Please add new compat syscalls above this comment and update
diff --git a/arch/arm64/include/uapi/asm/unistd.h b/arch/arm64/include/uapi/asm/unistd.h
index f83a70e07df8..ce2ee8f1e361 100644
--- a/arch/arm64/include/uapi/asm/unistd.h
+++ b/arch/arm64/include/uapi/asm/unistd.h
@@ -20,5 +20,6 @@
 #define __ARCH_WANT_SET_GET_RLIMIT
 #define __ARCH_WANT_TIME32_SYSCALLS
 #define __ARCH_WANT_SYS_CLONE3
+#define __ARCH_WANT_MEMFD_SECRET
 
 #include <asm-generic/unistd.h>
diff --git a/arch/riscv/include/asm/unistd.h b/arch/riscv/include/asm/unistd.h
index 977ee6181dab..6c316093a1e5 100644
--- a/arch/riscv/include/asm/unistd.h
+++ b/arch/riscv/include/asm/unistd.h
@@ -9,6 +9,7 @@
  */
 
 #define __ARCH_WANT_SYS_CLONE
+#define __ARCH_WANT_MEMFD_SECRET
 
 #include <uapi/asm/unistd.h>
 
diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
index 0d0667a9fbd7..1f3981b3f0e1 100644
--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl
@@ -445,3 +445,4 @@
 438	i386	pidfd_getfd		sys_pidfd_getfd
 439	i386	faccessat2		sys_faccessat2
 440	i386	process_madvise		sys_process_madvise
+441	i386	memfd_secret		sys_memfd_secret
diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
index 1f47e24fb65c..36c257e7b48e 100644
--- a/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/arch/x86/entry/syscalls/syscall_64.tbl
@@ -362,6 +362,7 @@
 438	common	pidfd_getfd		sys_pidfd_getfd
 439	common	faccessat2		sys_faccessat2
 440	common	process_madvise		sys_process_madvise
+441	common	memfd_secret		sys_memfd_secret
 
 #
 # x32-specific system call numbers start at 512 to avoid cache impact
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 2eda7678fe1d..fc077018c302 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -1008,6 +1008,7 @@ asmlinkage long sys_pidfd_send_signal(int pidfd, int sig,
 				       siginfo_t __user *info,
 				       unsigned int flags);
 asmlinkage long sys_pidfd_getfd(int pidfd, int fd, unsigned int flags);
+asmlinkage long sys_memfd_secret(unsigned long flags);
 
 /*
  * Architecture-specific system calls
diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
index 2056318988f7..bdfa71ad6fe0 100644
--- a/include/uapi/asm-generic/unistd.h
+++ b/include/uapi/asm-generic/unistd.h
@@ -860,8 +860,13 @@ __SYSCALL(__NR_faccessat2, sys_faccessat2)
 #define __NR_process_madvise 440
 __SYSCALL(__NR_process_madvise, sys_process_madvise)
 
+#ifdef __ARCH_WANT_MEMFD_SECRET
+#define __NR_memfd_secret 441
+__SYSCALL(__NR_memfd_secret, sys_memfd_secret)
+#endif
+
 #undef __NR_syscalls
-#define __NR_syscalls 441
+#define __NR_syscalls 442
 
 /*
  * 32 bit systems traditionally used different
diff --git a/scripts/checksyscalls.sh b/scripts/checksyscalls.sh
index a18b47695f55..b7609958ee36 100755
--- a/scripts/checksyscalls.sh
+++ b/scripts/checksyscalls.sh
@@ -40,6 +40,10 @@ cat << EOF
 #define __IGNORE_setrlimit	/* setrlimit */
 #endif
 
+#ifndef __ARCH_WANT_MEMFD_SECRET
+#define __IGNORE_memfd_secret
+#endif
+
 /* Missing flags argument */
 #define __IGNORE_renameat	/* renameat2 */
 
-- 
2.28.0


^ permalink raw reply	[flat|nested] 12+ messages in thread

* [PATCH v7 6/7] mm: secretmem: use PMD-size pages to amortize direct map fragmentation
  2020-10-26  8:37 [PATCH v7 0/7] mm: introduce memfd_secret system call to create "secret" memory areas Mike Rapoport
                   ` (4 preceding siblings ...)
  2020-10-26  8:37 ` [PATCH v7 5/7] arch, mm: wire up memfd_secret system call were relevant Mike Rapoport
@ 2020-10-26  8:37 ` Mike Rapoport
  2020-10-26  8:37 ` [PATCH v7 7/7] secretmem: test: add basic selftest for memfd_secret(2) Mike Rapoport
  6 siblings, 0 replies; 12+ messages in thread
From: Mike Rapoport @ 2020-10-26  8:37 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Alexander Viro, Andy Lutomirski, Arnd Bergmann, Borislav Petkov,
	Catalin Marinas, Christopher Lameter, Dan Williams, Dave Hansen,
	David Hildenbrand, Elena Reshetova, H. Peter Anvin, Ingo Molnar,
	James Bottomley, Kirill A. Shutemov, Matthew Wilcox,
	Mark Rutland, Mike Rapoport, Mike Rapoport, Michael Kerrisk,
	Palmer Dabbelt, Paul Walmsley, Peter Zijlstra, Rick Edgecombe,
	Shuah Khan, Thomas Gleixner, Tycho Andersen, Will Deacon,
	linux-api, linux-arch, linux-arm-kernel, linux-fsdevel, linux-mm,
	linux-kernel, linux-kselftest, linux-nvdimm, linux-riscv, x86

From: Mike Rapoport <rppt@linux.ibm.com>

Removing a PAGE_SIZE page from the direct map every time such page is
allocated for a secret memory mapping will cause severe fragmentation of
the direct map. This fragmentation can be reduced by using PMD-size pages
as a pool for small pages for secret memory mappings.

Add a gen_pool per secretmem inode and lazily populate this pool with
PMD-size pages.

Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
---
 mm/secretmem.c | 124 ++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 107 insertions(+), 17 deletions(-)

diff --git a/mm/secretmem.c b/mm/secretmem.c
index 2a63db2ed132..4f9e07d212be 100644
--- a/mm/secretmem.c
+++ b/mm/secretmem.c
@@ -12,8 +12,10 @@
 #include <linux/bitops.h>
 #include <linux/printk.h>
 #include <linux/pagemap.h>
+#include <linux/genalloc.h>
 #include <linux/syscalls.h>
 #include <linux/pseudo_fs.h>
+#include <linux/memcontrol.h>
 #include <linux/set_memory.h>
 #include <linux/sched/signal.h>
 
@@ -40,24 +42,80 @@
 #define SECRETMEM_FLAGS_MASK	SECRETMEM_MODE_MASK
 
 struct secretmem_ctx {
+	struct gen_pool *pool;
 	unsigned int mode;
 };
 
-static struct page *secretmem_alloc_page(gfp_t gfp)
+static int secretmem_pool_increase(struct secretmem_ctx *ctx, gfp_t gfp)
 {
+	unsigned long nr_pages = (1 << PMD_PAGE_ORDER);
+	struct gen_pool *pool = ctx->pool;
+	unsigned long addr;
+	struct page *page;
+	int err;
+
+	page = alloc_pages(gfp | __GFP_ACCOUNT, PMD_PAGE_ORDER);
+	if (!page)
+		return -ENOMEM;
+
+	addr = (unsigned long)page_address(page);
+
+	err = set_direct_map_invalid_noflush(page, nr_pages);
+	if (err)
+		goto err_free_pages;
+
+	err = gen_pool_add(pool, addr, PMD_SIZE, NUMA_NO_NODE);
+	if (err)
+		goto err_set_direct_map;
+
+	split_page(page, PMD_PAGE_ORDER);
+	flush_tlb_kernel_range(addr, addr + PMD_SIZE);
+
+	return 0;
+
+err_set_direct_map:
 	/*
-	 * FIXME: use a cache of large pages to reduce the direct map
-	 * fragmentation
+	 * If a split of PUD-size page was required, it already happened
+	 * when we made the pages invalid which guarantees that this call
+	 * won't fail
 	 */
-	return alloc_page(gfp);
+	set_direct_map_default_noflush(page, nr_pages);
+
+err_free_pages:
+	__free_pages(page, PMD_PAGE_ORDER);
+	return err;
+}
+
+static struct page *secretmem_alloc_page(struct secretmem_ctx *ctx,
+					 gfp_t gfp)
+{
+	struct gen_pool *pool = ctx->pool;
+	unsigned long addr;
+	struct page *page;
+	int err;
+
+	if (gen_pool_avail(pool) < PAGE_SIZE) {
+		err = secretmem_pool_increase(ctx, gfp);
+		if (err)
+			return NULL;
+	}
+
+	addr = gen_pool_alloc(pool, PAGE_SIZE);
+	if (!addr)
+		return NULL;
+
+	page = virt_to_page(addr);
+	get_page(page);
+
+	return page;
 }
 
 static vm_fault_t secretmem_fault(struct vm_fault *vmf)
 {
+	struct secretmem_ctx *ctx = vmf->vma->vm_file->private_data;
 	struct address_space *mapping = vmf->vma->vm_file->f_mapping;
 	struct inode *inode = file_inode(vmf->vma->vm_file);
 	pgoff_t offset = vmf->pgoff;
-	unsigned long addr;
 	struct page *page;
 	int ret = 0;
 
@@ -66,22 +124,22 @@ static vm_fault_t secretmem_fault(struct vm_fault *vmf)
 
 	page = find_get_entry(mapping, offset);
 	if (!page) {
-		page = secretmem_alloc_page(vmf->gfp_mask);
+		page = secretmem_alloc_page(ctx, vmf->gfp_mask);
 		if (!page)
 			return vmf_error(-ENOMEM);
 
+		/*
+		 * add_to_page_cache() calls mem_cgroup_charge(), so we
+		 * need to uncharge here to avoid double accounting
+		 */
+		memcg_kmem_uncharge_page(page, 0);
+
 		ret = add_to_page_cache(page, mapping, offset, vmf->gfp_mask);
 		if (unlikely(ret))
 			goto err_put_page;
 
-		ret = set_direct_map_invalid_noflush(page, 1);
-		if (ret)
-			goto err_del_page_cache;
-
-		addr = (unsigned long)page_address(page);
-		flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
-
 		__SetPageUptodate(page);
+		set_page_private(page, (unsigned long)ctx);
 
 		ret = VM_FAULT_LOCKED;
 	}
@@ -89,8 +147,6 @@ static vm_fault_t secretmem_fault(struct vm_fault *vmf)
 	vmf->page = page;
 	return ret;
 
-err_del_page_cache:
-	delete_from_page_cache(page);
 err_put_page:
 	put_page(page);
 	return vmf_error(ret);
@@ -143,7 +199,11 @@ static int secretmem_migratepage(struct address_space *mapping,
 
 static void secretmem_freepage(struct page *page)
 {
-	set_direct_map_default_noflush(page, 1);
+	unsigned long addr = (unsigned long)page_address(page);
+	struct secretmem_ctx *ctx = (struct secretmem_ctx *)page_private(page);
+	struct gen_pool *pool = ctx->pool;
+
+	gen_pool_free(pool, addr, PAGE_SIZE);
 }
 
 static const struct address_space_operations secretmem_aops = {
@@ -178,13 +238,18 @@ static struct file *secretmem_file_create(unsigned long flags)
 	if (!ctx)
 		goto err_free_inode;
 
+	ctx->pool = gen_pool_create(PAGE_SHIFT, NUMA_NO_NODE);
+	if (!ctx->pool)
+		goto err_free_ctx;
+
 	file = alloc_file_pseudo(inode, secretmem_mnt, "secretmem",
 				 O_RDWR, &secretmem_fops);
 	if (IS_ERR(file))
-		goto err_free_ctx;
+		goto err_free_pool;
 
 	mapping_set_unevictable(inode->i_mapping);
 
+	inode->i_private = ctx;
 	inode->i_mapping->private_data = ctx;
 	inode->i_mapping->a_ops = &secretmem_aops;
 
@@ -198,6 +263,8 @@ static struct file *secretmem_file_create(unsigned long flags)
 
 	return file;
 
+err_free_pool:
+	gen_pool_destroy(ctx->pool);
 err_free_ctx:
 	kfree(ctx);
 err_free_inode:
@@ -236,11 +303,34 @@ SYSCALL_DEFINE1(memfd_secret, unsigned long, flags)
 	return err;
 }
 
+static void secretmem_cleanup_chunk(struct gen_pool *pool,
+				    struct gen_pool_chunk *chunk, void *data)
+{
+	unsigned long start = chunk->start_addr;
+	unsigned long end = chunk->end_addr;
+	unsigned long nr_pages, addr;
+
+	nr_pages = (end - start + 1) / PAGE_SIZE;
+	__kernel_map_pages(virt_to_page(start), nr_pages, 1);
+
+	for (addr = start; addr < end; addr += PAGE_SIZE)
+		put_page(virt_to_page(addr));
+}
+
+static void secretmem_cleanup_pool(struct secretmem_ctx *ctx)
+{
+	struct gen_pool *pool = ctx->pool;
+
+	gen_pool_for_each_chunk(pool, secretmem_cleanup_chunk, ctx);
+	gen_pool_destroy(pool);
+}
+
 static void secretmem_evict_inode(struct inode *inode)
 {
 	struct secretmem_ctx *ctx = inode->i_private;
 
 	truncate_inode_pages_final(&inode->i_data);
+	secretmem_cleanup_pool(ctx);
 	clear_inode(inode);
 	kfree(ctx);
 }
-- 
2.28.0


^ permalink raw reply	[flat|nested] 12+ messages in thread

* [PATCH v7 7/7] secretmem: test: add basic selftest for memfd_secret(2)
  2020-10-26  8:37 [PATCH v7 0/7] mm: introduce memfd_secret system call to create "secret" memory areas Mike Rapoport
                   ` (5 preceding siblings ...)
  2020-10-26  8:37 ` [PATCH v7 6/7] mm: secretmem: use PMD-size pages to amortize direct map fragmentation Mike Rapoport
@ 2020-10-26  8:37 ` Mike Rapoport
  6 siblings, 0 replies; 12+ messages in thread
From: Mike Rapoport @ 2020-10-26  8:37 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Alexander Viro, Andy Lutomirski, Arnd Bergmann, Borislav Petkov,
	Catalin Marinas, Christopher Lameter, Dan Williams, Dave Hansen,
	David Hildenbrand, Elena Reshetova, H. Peter Anvin, Ingo Molnar,
	James Bottomley, Kirill A. Shutemov, Matthew Wilcox,
	Mark Rutland, Mike Rapoport, Mike Rapoport, Michael Kerrisk,
	Palmer Dabbelt, Paul Walmsley, Peter Zijlstra, Rick Edgecombe,
	Shuah Khan, Thomas Gleixner, Tycho Andersen, Will Deacon,
	linux-api, linux-arch, linux-arm-kernel, linux-fsdevel, linux-mm,
	linux-kernel, linux-kselftest, linux-nvdimm, linux-riscv, x86

From: Mike Rapoport <rppt@linux.ibm.com>

The test verifies that file descriptor created with memfd_secret does
not allow read/write operations, that secret memory mappings respect
RLIMIT_MEMLOCK and that remote accesses with process_vm_read() and
ptrace() to the secret memory fail.

Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
---
 tools/testing/selftests/vm/.gitignore     |   1 +
 tools/testing/selftests/vm/Makefile       |   3 +-
 tools/testing/selftests/vm/memfd_secret.c | 296 ++++++++++++++++++++++
 tools/testing/selftests/vm/run_vmtests    |  17 ++
 4 files changed, 316 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/vm/memfd_secret.c

diff --git a/tools/testing/selftests/vm/.gitignore b/tools/testing/selftests/vm/.gitignore
index 849e8226395a..8a951fed3c3f 100644
--- a/tools/testing/selftests/vm/.gitignore
+++ b/tools/testing/selftests/vm/.gitignore
@@ -20,3 +20,4 @@ va_128TBswitch
 map_fixed_noreplace
 write_to_hugetlbfs
 hmm-tests
+memfd_secret
diff --git a/tools/testing/selftests/vm/Makefile b/tools/testing/selftests/vm/Makefile
index 30873b19d04b..0fc87d0b140a 100644
--- a/tools/testing/selftests/vm/Makefile
+++ b/tools/testing/selftests/vm/Makefile
@@ -38,6 +38,7 @@ TEST_GEN_FILES += thuge-gen
 TEST_GEN_FILES += transhuge-stress
 TEST_GEN_FILES += userfaultfd
 TEST_GEN_FILES += khugepaged
+TEST_GEN_FILES += memfd_secret
 
 ifeq ($(ARCH),x86_64)
 CAN_BUILD_I386 := $(shell ./../x86/check_cc.sh $(CC) ../x86/trivial_32bit_program.c -m32)
@@ -129,4 +130,4 @@ endif
 
 $(OUTPUT)/userfaultfd: LDLIBS += -lpthread
 
-$(OUTPUT)/mlock-random-test: LDLIBS += -lcap
+$(OUTPUT)/mlock-random-test $(OUTPUT)/memfd_secret: LDLIBS += -lcap
diff --git a/tools/testing/selftests/vm/memfd_secret.c b/tools/testing/selftests/vm/memfd_secret.c
new file mode 100644
index 000000000000..31be20732e85
--- /dev/null
+++ b/tools/testing/selftests/vm/memfd_secret.c
@@ -0,0 +1,296 @@
+#define _GNU_SOURCE
+#include <sys/uio.h>
+#include <sys/mman.h>
+#include <sys/wait.h>
+#include <sys/types.h>
+#include <sys/ptrace.h>
+#include <sys/syscall.h>
+#include <sys/resource.h>
+#include <sys/capability.h>
+
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <stdio.h>
+
+#include "../kselftest.h"
+
+#define fail(fmt, ...) ksft_test_result_fail(fmt, ##__VA_ARGS__)
+#define pass(fmt, ...) ksft_test_result_pass(fmt, ##__VA_ARGS__)
+#define skip(fmt, ...) ksft_test_result_skip(fmt, ##__VA_ARGS__)
+
+#ifdef __NR_memfd_secret
+
+#include <linux/secretmem.h>
+
+#define PATTERN	0x55
+
+static const int prot = PROT_READ | PROT_WRITE;
+static const int mode = MAP_SHARED;
+
+static unsigned long page_size;
+static unsigned long mlock_limit_cur;
+static unsigned long mlock_limit_max;
+
+static int memfd_secret(unsigned long flags)
+{
+	return syscall(__NR_memfd_secret, flags);
+}
+
+static void test_file_apis(int fd)
+{
+	char buf[64];
+
+	if ((read(fd, buf, sizeof(buf)) >= 0) ||
+	    (write(fd, buf, sizeof(buf)) >= 0) ||
+	    (pread(fd, buf, sizeof(buf), 0) >= 0) ||
+	    (pwrite(fd, buf, sizeof(buf), 0) >= 0))
+		fail("unexpected file IO\n");
+	else
+		pass("file IO is blocked as expected\n");
+}
+
+static void test_mlock_limit(int fd)
+{
+	size_t len;
+	char *mem;
+
+	len = mlock_limit_cur;
+	mem = mmap(NULL, len, prot, mode, fd, 0);
+	if (mem == MAP_FAILED) {
+		fail("unable to mmap secret memory\n");
+		return;
+	}
+	munmap(mem, len);
+
+	len = mlock_limit_max * 2;
+	mem = mmap(NULL, len, prot, mode, fd, 0);
+	if (mem != MAP_FAILED) {
+		fail("unexpected mlock limit violation\n");
+		munmap(mem, len);
+		return;
+	}
+
+	pass("mlock limit is respected\n");
+}
+
+static void try_process_vm_read(int fd, int pipefd[2])
+{
+	struct iovec liov, riov;
+	char buf[64];
+	char *mem;
+
+	if (read(pipefd[0], &mem, sizeof(mem)) < 0) {
+		fail("pipe write: %s\n", strerror(errno));
+		exit(KSFT_FAIL);
+	}
+
+	liov.iov_len = riov.iov_len = sizeof(buf);
+	liov.iov_base = buf;
+	riov.iov_base = mem;
+
+	if (process_vm_readv(getppid(), &liov, 1, &riov, 1, 0) < 0) {
+		if (errno == ENOSYS)
+			exit(KSFT_SKIP);
+		exit(KSFT_PASS);
+	}
+
+	exit(KSFT_FAIL);
+}
+
+static void try_ptrace(int fd, int pipefd[2])
+{
+	pid_t ppid = getppid();
+	int status;
+	char *mem;
+	long ret;
+
+	if (read(pipefd[0], &mem, sizeof(mem)) < 0) {
+		perror("pipe write");
+		exit(KSFT_FAIL);
+	}
+
+	ret = ptrace(PTRACE_ATTACH, ppid, 0, 0);
+	if (ret) {
+		perror("ptrace_attach");
+		exit(KSFT_FAIL);
+	}
+
+	ret = waitpid(ppid, &status, WUNTRACED);
+	if ((ret != ppid) || !(WIFSTOPPED(status))) {
+		fprintf(stderr, "weird waitppid result %ld stat %x\n",
+			ret, status);
+		exit(KSFT_FAIL);
+	}
+
+	/* this access should fail and the task should be killed */
+	ret = ptrace(PTRACE_PEEKDATA, ppid, mem, 0);
+	if (ret < 0) {
+		perror("ptrace_peek");
+		exit(KSFT_FAIL);
+	}
+
+	/* we shouldn't survive PTRACE_PEEKDATA */
+	exit(KSFT_FAIL);
+}
+
+static void check_child_status(pid_t pid, const char *name)
+{
+	int status;
+
+	waitpid(pid, &status, 0);
+
+	if (WIFEXITED(status) && WEXITSTATUS(status) == KSFT_SKIP) {
+		skip("%s is not supported\n", name);
+		return;
+	}
+
+	if ((WIFEXITED(status) && WEXITSTATUS(status) == KSFT_PASS) ||
+	    WIFSIGNALED(status)) {
+		pass("%s failed as expected\n", name);
+		return;
+	}
+
+	fail("%s: unexpected memory access\n", name);
+}
+
+static void test_remote_access(int fd, const char *name,
+			       void (*func)(int fd, int pipefd[2]))
+{
+	int pipefd[2];
+	pid_t pid;
+	char *mem;
+
+	if (pipe(pipefd)) {
+		fail("pipe failed: %s\n", strerror(errno));
+		return;
+	}
+
+	pid = fork();
+	if (pid < 0) {
+		fail("fork failed: %s\n", strerror(errno));
+		return;
+	}
+
+	if (pid == 0) {
+		func(fd, pipefd);
+		return;
+	}
+
+	mem = mmap(NULL, page_size, prot, mode, fd, 0);
+	if (mem == MAP_FAILED) {
+		fail("Unable to mmap secret memory\n");
+		return;
+	}
+
+	ftruncate(fd, page_size);
+	memset(mem, PATTERN, page_size);
+
+	if (write(pipefd[1], &mem, sizeof(mem)) < 0) {
+		fail("pipe write: %s\n", strerror(errno));
+		return;
+	}
+
+	check_child_status(pid, name);
+}
+
+static void test_process_vm_read(int fd)
+{
+	test_remote_access(fd, "process_vm_read", try_process_vm_read);
+}
+
+static void test_ptrace(int fd)
+{
+	test_remote_access(fd, "ptrace", try_ptrace);
+}
+
+static int set_cap_limits(rlim_t max)
+{
+	struct rlimit new;
+	cap_t cap = cap_init();
+
+	new.rlim_cur = max;
+	new.rlim_max = max;
+	if (setrlimit(RLIMIT_MEMLOCK, &new)) {
+		perror("setrlimit() returns error");
+		return -1;
+	}
+
+	/* drop capabilities including CAP_IPC_LOCK */
+	if (cap_set_proc(cap)) {
+		perror("cap_set_proc() returns error");
+		return -2;
+	}
+
+	return 0;
+}
+
+static void prepare(void)
+{
+	struct rlimit rlim;
+
+	page_size = sysconf(_SC_PAGE_SIZE);
+	if (!page_size)
+		ksft_exit_fail_msg("Failed to get page size %s\n",
+				   strerror(errno));
+
+	if (getrlimit(RLIMIT_MEMLOCK, &rlim))
+		ksft_exit_fail_msg("Unable to detect mlock limit: %s\n",
+				   strerror(errno));
+
+	mlock_limit_cur = rlim.rlim_cur;
+	mlock_limit_max = rlim.rlim_max;
+
+	printf("page_size: %ld, mlock.soft: %ld, mlock.hard: %ld\n",
+	       page_size, mlock_limit_cur, mlock_limit_max);
+
+	if (page_size > mlock_limit_cur)
+		mlock_limit_cur = page_size;
+	if (page_size > mlock_limit_max)
+		mlock_limit_max = page_size;
+
+	if (set_cap_limits(mlock_limit_max))
+		ksft_exit_fail_msg("Unable to set mlock limit: %s\n",
+				   strerror(errno));
+}
+
+#define NUM_TESTS 4
+
+int main(int argc, char *argv[])
+{
+	int fd;
+
+	prepare();
+
+	ksft_print_header();
+	ksft_set_plan(NUM_TESTS);
+
+	fd = memfd_secret(0);
+	if (fd < 0) {
+		if (errno == ENOSYS)
+			ksft_exit_skip("memfd_secret is not supported\n");
+		else
+			ksft_exit_fail_msg("memfd_secret failed: %s\n",
+					   strerror(errno));
+	}
+
+	test_mlock_limit(fd);
+	test_file_apis(fd);
+	test_process_vm_read(fd);
+	test_ptrace(fd);
+
+	close(fd);
+
+	ksft_exit(!ksft_get_fail_cnt());
+}
+
+#else /* __NR_memfd_secret */
+
+int main(int argc, char *argv[])
+{
+	printf("skip: skipping memfd_secret test (missing __NR_memfd_secret)\n");
+	return KSFT_SKIP;
+}
+
+#endif /* __NR_memfd_secret */
diff --git a/tools/testing/selftests/vm/run_vmtests b/tools/testing/selftests/vm/run_vmtests
index a3f4f30f0a2e..bee7365f3cc2 100755
--- a/tools/testing/selftests/vm/run_vmtests
+++ b/tools/testing/selftests/vm/run_vmtests
@@ -323,4 +323,21 @@ else
 	exitcode=1
 fi
 
+echo "running memfd_secret test"
+echo "------------------------------------"
+./memfd_secret
+ret_val=$?
+
+if [ $ret_val -eq 0 ]; then
+	echo "[PASS]"
+elif [ $ret_val -eq $ksft_skip ]; then
+	echo "[SKIP]"
+	exitcode=$ksft_skip
+else
+	echo "[FAIL]"
+	exitcode=1
+fi
+
+exit $exitcode
+
 exit $exitcode
-- 
2.28.0


^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: [PATCH v7 3/7] set_memory: allow set_direct_map_*_noflush() for multiple pages
  2020-10-26  8:37 ` [PATCH v7 3/7] set_memory: allow set_direct_map_*_noflush() for multiple pages Mike Rapoport
@ 2020-10-26 19:01   ` Edgecombe, Rick P
  2020-10-27  8:12     ` David Hildenbrand
  0 siblings, 1 reply; 12+ messages in thread
From: Edgecombe, Rick P @ 2020-10-26 19:01 UTC (permalink / raw)
  To: rppt, akpm
  Cc: tycho, david, cl, hpa, peterz, catalin.marinas, linux-kselftest,
	dave.hansen, will, linux-mm, kirill, viro, rppt, linux-arch,
	Williams, Dan J, bp, willy, luto, arnd, shuah, tglx,
	linux-nvdimm, linux-riscv, x86, linux-arm-kernel, linux-fsdevel,
	Reshetova, Elena, palmer, mingo, mtk.manpages, linux-kernel,
	linux-api, jejb, paul.walmsley, mark.rutland

On Mon, 2020-10-26 at 10:37 +0200, Mike Rapoport wrote:
> +++ b/arch/x86/mm/pat/set_memory.c
> @@ -2184,14 +2184,14 @@ static int __set_pages_np(struct page *page,
> int numpages)
>         return __change_page_attr_set_clr(&cpa, 0);
>  }
>  
> -int set_direct_map_invalid_noflush(struct page *page)
> +int set_direct_map_invalid_noflush(struct page *page, int numpages)
>  {
> -       return __set_pages_np(page, 1);
> +       return __set_pages_np(page, numpages);
>  }
>  
> -int set_direct_map_default_noflush(struct page *page)
> +int set_direct_map_default_noflush(struct page *page, int numpages)
>  {
> -       return __set_pages_p(page, 1);
> +       return __set_pages_p(page, numpages);
>  }

Somewhat related to your other series, this could result in large NP
pages and trip up hibernate.

^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: [PATCH v7 3/7] set_memory: allow set_direct_map_*_noflush() for multiple pages
  2020-10-26 19:01   ` Edgecombe, Rick P
@ 2020-10-27  8:12     ` David Hildenbrand
  2020-10-27  9:48       ` Mike Rapoport
  0 siblings, 1 reply; 12+ messages in thread
From: David Hildenbrand @ 2020-10-27  8:12 UTC (permalink / raw)
  To: Edgecombe, Rick P, rppt, akpm
  Cc: tycho, cl, hpa, peterz, catalin.marinas, linux-kselftest,
	dave.hansen, will, linux-mm, kirill, viro, rppt, linux-arch,
	Williams, Dan J, bp, willy, luto, arnd, shuah, tglx,
	linux-nvdimm, linux-riscv, x86, linux-arm-kernel, linux-fsdevel,
	Reshetova, Elena, palmer, mingo, mtk.manpages, linux-kernel,
	linux-api, jejb, paul.walmsley, mark.rutland

On 26.10.20 20:01, Edgecombe, Rick P wrote:
> On Mon, 2020-10-26 at 10:37 +0200, Mike Rapoport wrote:
>> +++ b/arch/x86/mm/pat/set_memory.c
>> @@ -2184,14 +2184,14 @@ static int __set_pages_np(struct page *page,
>> int numpages)
>>         return __change_page_attr_set_clr(&cpa, 0);
>>  }
>>  
>> -int set_direct_map_invalid_noflush(struct page *page)
>> +int set_direct_map_invalid_noflush(struct page *page, int numpages)
>>  {
>> -       return __set_pages_np(page, 1);
>> +       return __set_pages_np(page, numpages);
>>  }
>>  
>> -int set_direct_map_default_noflush(struct page *page)
>> +int set_direct_map_default_noflush(struct page *page, int numpages)
>>  {
>> -       return __set_pages_p(page, 1);
>> +       return __set_pages_p(page, numpages);
>>  }
> 
> Somewhat related to your other series, this could result in large NP
> pages and trip up hibernate.
> 

It feels somewhat desirable to disable hibernation once secretmem is
enabled, right? Otherwise you'll be writing out your secrets to swap,
where they will remain even after booting up again ...

Skipping secretmem pages when hibernating is the wrong approach I guess ...

-- 
Thanks,

David / dhildenb


^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: [PATCH v7 1/7] mm: add definition of PMD_PAGE_ORDER
  2020-10-26  8:37 ` [PATCH v7 1/7] mm: add definition of PMD_PAGE_ORDER Mike Rapoport
@ 2020-10-27  8:26   ` David Hildenbrand
  0 siblings, 0 replies; 12+ messages in thread
From: David Hildenbrand @ 2020-10-27  8:26 UTC (permalink / raw)
  To: Mike Rapoport, Andrew Morton
  Cc: Alexander Viro, Andy Lutomirski, Arnd Bergmann, Borislav Petkov,
	Catalin Marinas, Christopher Lameter, Dan Williams, Dave Hansen,
	Elena Reshetova, H. Peter Anvin, Ingo Molnar, James Bottomley,
	Kirill A. Shutemov, Matthew Wilcox, Mark Rutland, Mike Rapoport,
	Michael Kerrisk, Palmer Dabbelt, Paul Walmsley, Peter Zijlstra,
	Rick Edgecombe, Shuah Khan, Thomas Gleixner, Tycho Andersen,
	Will Deacon, linux-api, linux-arch, linux-arm-kernel,
	linux-fsdevel, linux-mm, linux-kernel, linux-kselftest,
	linux-nvdimm, linux-riscv, x86

On 26.10.20 09:37, Mike Rapoport wrote:
> From: Mike Rapoport <rppt@linux.ibm.com>
> 
> The definition of PMD_PAGE_ORDER denoting the number of base pages in the
> second-level leaf page is already used by DAX and maybe handy in other
> cases as well.
> 
> Several architectures already have definition of PMD_ORDER as the size of
> second level page table, so to avoid conflict with these definitions use
> PMD_PAGE_ORDER name and update DAX respectively.
> 
> Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>

Reviewed-by: David Hildenbrand <david@redhat.com>


-- 
Thanks,

David / dhildenb


^ permalink raw reply	[flat|nested] 12+ messages in thread

* Re: [PATCH v7 3/7] set_memory: allow set_direct_map_*_noflush() for multiple pages
  2020-10-27  8:12     ` David Hildenbrand
@ 2020-10-27  9:48       ` Mike Rapoport
  0 siblings, 0 replies; 12+ messages in thread
From: Mike Rapoport @ 2020-10-27  9:48 UTC (permalink / raw)
  To: David Hildenbrand
  Cc: Edgecombe, Rick P, akpm, tycho, cl, hpa, peterz, catalin.marinas,
	linux-kselftest, dave.hansen, will, linux-mm, kirill, viro, rppt,
	linux-arch, Williams, Dan J, bp, willy, luto, arnd, shuah, tglx,
	linux-nvdimm, linux-riscv, x86, linux-arm-kernel, linux-fsdevel,
	Reshetova, Elena, palmer, mingo, mtk.manpages, linux-kernel,
	linux-api, jejb, paul.walmsley, mark.rutland

On Tue, Oct 27, 2020 at 09:12:23AM +0100, David Hildenbrand wrote:
> On 26.10.20 20:01, Edgecombe, Rick P wrote:
> > On Mon, 2020-10-26 at 10:37 +0200, Mike Rapoport wrote:
> >> +++ b/arch/x86/mm/pat/set_memory.c
> >> @@ -2184,14 +2184,14 @@ static int __set_pages_np(struct page *page,
> >> int numpages)
> >>         return __change_page_attr_set_clr(&cpa, 0);
> >>  }
> >>  
> >> -int set_direct_map_invalid_noflush(struct page *page)
> >> +int set_direct_map_invalid_noflush(struct page *page, int numpages)
> >>  {
> >> -       return __set_pages_np(page, 1);
> >> +       return __set_pages_np(page, numpages);
> >>  }
> >>  
> >> -int set_direct_map_default_noflush(struct page *page)
> >> +int set_direct_map_default_noflush(struct page *page, int numpages)
> >>  {
> >> -       return __set_pages_p(page, 1);
> >> +       return __set_pages_p(page, numpages);
> >>  }
> > 
> > Somewhat related to your other series, this could result in large NP
> > pages and trip up hibernate.
> > 
> 
> It feels somewhat desirable to disable hibernation once secretmem is
> enabled, right? Otherwise you'll be writing out your secrets to swap,
> where they will remain even after booting up again ...
> 
> Skipping secretmem pages when hibernating is the wrong approach I guess ...

Completely agree.
I'll look into preventing hibernation from touching secretmem.

> -- 
> Thanks,
> 
> David / dhildenb
> 

-- 
Sincerely yours,
Mike.

^ permalink raw reply	[flat|nested] 12+ messages in thread

end of thread, back to index

Thread overview: 12+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-10-26  8:37 [PATCH v7 0/7] mm: introduce memfd_secret system call to create "secret" memory areas Mike Rapoport
2020-10-26  8:37 ` [PATCH v7 1/7] mm: add definition of PMD_PAGE_ORDER Mike Rapoport
2020-10-27  8:26   ` David Hildenbrand
2020-10-26  8:37 ` [PATCH v7 2/7] mmap: make mlock_future_check() global Mike Rapoport
2020-10-26  8:37 ` [PATCH v7 3/7] set_memory: allow set_direct_map_*_noflush() for multiple pages Mike Rapoport
2020-10-26 19:01   ` Edgecombe, Rick P
2020-10-27  8:12     ` David Hildenbrand
2020-10-27  9:48       ` Mike Rapoport
2020-10-26  8:37 ` [PATCH v7 4/7] mm: introduce memfd_secret system call to create "secret" memory areas Mike Rapoport
2020-10-26  8:37 ` [PATCH v7 5/7] arch, mm: wire up memfd_secret system call were relevant Mike Rapoport
2020-10-26  8:37 ` [PATCH v7 6/7] mm: secretmem: use PMD-size pages to amortize direct map fragmentation Mike Rapoport
2020-10-26  8:37 ` [PATCH v7 7/7] secretmem: test: add basic selftest for memfd_secret(2) Mike Rapoport

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