Linux-parisc archive on lore.kernel.org
 help / color / Atom feed
* clean up and streamline probe_kernel_* and friends v3
@ 2020-05-19 13:44 Christoph Hellwig
  2020-05-19 13:44 ` [PATCH 01/20] maccess: unexport probe_kernel_write and probe_user_write Christoph Hellwig
                   ` (20 more replies)
  0 siblings, 21 replies; 33+ messages in thread
From: Christoph Hellwig @ 2020-05-19 13:44 UTC (permalink / raw)
  To: x86, Alexei Starovoitov, Daniel Borkmann, Masami Hiramatsu,
	Linus Torvalds, Andrew Morton
  Cc: linux-parisc, linux-um, netdev, bpf, linux-mm, linux-kernel

Hi all,

this series start cleaning up the safe kernel and user memory probing
helpers in mm/maccess.c, and then allows architectures to implement
the kernel probing without overriding the address space limit and
temporarily allowing access to user memory.  It then switches x86
over to this new mechanism by reusing the unsafe_* uaccess logic.

This version also switches to the saner copy_{from,to}_kernel_nofault
naming suggested by Linus.

I kept the x86 helprs as-is without calling unsage_{get,put}_user as
that avoids a number of hard to trace casts, and it will still work
with the asm-goto based version easily.

Changes since v2:
 - rebased on 5.7-rc6 with the bpf trace format string changes
 - rename arch_kernel_read to __get_kernel_nofault and arch_kernel_write
   to __put_kernel_nofault
 - clean up the tracers to only allowd "mixed" reads when the kernel
   has non-overlapping address spaces

^ permalink raw reply	[flat|nested] 33+ messages in thread

* [PATCH 01/20] maccess: unexport probe_kernel_write and probe_user_write
  2020-05-19 13:44 clean up and streamline probe_kernel_* and friends v3 Christoph Hellwig
@ 2020-05-19 13:44 ` Christoph Hellwig
  2020-05-19 13:44 ` [PATCH 02/20] maccess: remove various unused weak aliases Christoph Hellwig
                   ` (19 subsequent siblings)
  20 siblings, 0 replies; 33+ messages in thread
From: Christoph Hellwig @ 2020-05-19 13:44 UTC (permalink / raw)
  To: x86, Alexei Starovoitov, Daniel Borkmann, Masami Hiramatsu,
	Linus Torvalds, Andrew Morton
  Cc: linux-parisc, linux-um, netdev, bpf, linux-mm, linux-kernel

These two functions are not used by any modular code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/maccess.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/mm/maccess.c b/mm/maccess.c
index 3ca8d97e50106..cf21e604f78cb 100644
--- a/mm/maccess.c
+++ b/mm/maccess.c
@@ -121,7 +121,6 @@ long __probe_kernel_write(void *dst, const void *src, size_t size)
 
 	return ret;
 }
-EXPORT_SYMBOL_GPL(probe_kernel_write);
 
 /**
  * probe_user_write(): safely attempt to write to a user-space location
@@ -148,7 +147,6 @@ long __probe_user_write(void __user *dst, const void *src, size_t size)
 
 	return ret;
 }
-EXPORT_SYMBOL_GPL(probe_user_write);
 
 /**
  * strncpy_from_unsafe: - Copy a NUL terminated string from unsafe address.
-- 
2.26.2


^ permalink raw reply	[flat|nested] 33+ messages in thread

* [PATCH 02/20] maccess: remove various unused weak aliases
  2020-05-19 13:44 clean up and streamline probe_kernel_* and friends v3 Christoph Hellwig
  2020-05-19 13:44 ` [PATCH 01/20] maccess: unexport probe_kernel_write and probe_user_write Christoph Hellwig
@ 2020-05-19 13:44 ` Christoph Hellwig
  2020-05-19 13:44 ` [PATCH 03/20] maccess: remove duplicate kerneldoc comments Christoph Hellwig
                   ` (18 subsequent siblings)
  20 siblings, 0 replies; 33+ messages in thread
From: Christoph Hellwig @ 2020-05-19 13:44 UTC (permalink / raw)
  To: x86, Alexei Starovoitov, Daniel Borkmann, Masami Hiramatsu,
	Linus Torvalds, Andrew Morton
  Cc: linux-parisc, linux-um, netdev, bpf, linux-mm, linux-kernel

maccess tends to define lots of underscore prefixed symbols that then
have other weak aliases.  But except for two cases they are never
actually used, so remove them.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/linux/uaccess.h |  3 ---
 mm/maccess.c            | 19 +++----------------
 2 files changed, 3 insertions(+), 19 deletions(-)

diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index 67f016010aad5..a2c606a403745 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -324,7 +324,6 @@ extern long __probe_kernel_read(void *dst, const void *src, size_t size);
  * happens, handle that and return -EFAULT.
  */
 extern long probe_user_read(void *dst, const void __user *src, size_t size);
-extern long __probe_user_read(void *dst, const void __user *src, size_t size);
 
 /*
  * probe_kernel_write(): safely attempt to write to a location
@@ -336,7 +335,6 @@ extern long __probe_user_read(void *dst, const void __user *src, size_t size);
  * happens, handle that and return -EFAULT.
  */
 extern long notrace probe_kernel_write(void *dst, const void *src, size_t size);
-extern long notrace __probe_kernel_write(void *dst, const void *src, size_t size);
 
 /*
  * probe_user_write(): safely attempt to write to a location in user space
@@ -348,7 +346,6 @@ extern long notrace __probe_kernel_write(void *dst, const void *src, size_t size
  * happens, handle that and return -EFAULT.
  */
 extern long notrace probe_user_write(void __user *dst, const void *src, size_t size);
-extern long notrace __probe_user_write(void __user *dst, const void *src, size_t size);
 
 extern long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count);
 extern long strncpy_from_unsafe_strict(char *dst, const void *unsafe_addr,
diff --git a/mm/maccess.c b/mm/maccess.c
index cf21e604f78cb..4e7f3b6eb05ae 100644
--- a/mm/maccess.c
+++ b/mm/maccess.c
@@ -79,11 +79,7 @@ EXPORT_SYMBOL_GPL(probe_kernel_read);
  * Safely read from user address @src to the buffer at @dst. If a kernel fault
  * happens, handle that and return -EFAULT.
  */
-
-long __weak probe_user_read(void *dst, const void __user *src, size_t size)
-    __attribute__((alias("__probe_user_read")));
-
-long __probe_user_read(void *dst, const void __user *src, size_t size)
+long probe_user_read(void *dst, const void __user *src, size_t size)
 {
 	long ret = -EFAULT;
 	mm_segment_t old_fs = get_fs();
@@ -106,11 +102,7 @@ EXPORT_SYMBOL_GPL(probe_user_read);
  * Safely write to address @dst from the buffer at @src.  If a kernel fault
  * happens, handle that and return -EFAULT.
  */
-
-long __weak probe_kernel_write(void *dst, const void *src, size_t size)
-    __attribute__((alias("__probe_kernel_write")));
-
-long __probe_kernel_write(void *dst, const void *src, size_t size)
+long probe_kernel_write(void *dst, const void *src, size_t size)
 {
 	long ret;
 	mm_segment_t old_fs = get_fs();
@@ -131,11 +123,7 @@ long __probe_kernel_write(void *dst, const void *src, size_t size)
  * Safely write to address @dst from the buffer at @src.  If a kernel fault
  * happens, handle that and return -EFAULT.
  */
-
-long __weak probe_user_write(void __user *dst, const void *src, size_t size)
-    __attribute__((alias("__probe_user_write")));
-
-long __probe_user_write(void __user *dst, const void *src, size_t size)
+long probe_user_write(void __user *dst, const void *src, size_t size)
 {
 	long ret = -EFAULT;
 	mm_segment_t old_fs = get_fs();
@@ -171,7 +159,6 @@ long __probe_user_write(void __user *dst, const void *src, size_t size)
  * probing memory on a user address range where strncpy_from_unsafe_user() is
  * supposed to be used instead.
  */
-
 long __weak strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count)
     __attribute__((alias("__strncpy_from_unsafe")));
 
-- 
2.26.2


^ permalink raw reply	[flat|nested] 33+ messages in thread

* [PATCH 03/20] maccess: remove duplicate kerneldoc comments
  2020-05-19 13:44 clean up and streamline probe_kernel_* and friends v3 Christoph Hellwig
  2020-05-19 13:44 ` [PATCH 01/20] maccess: unexport probe_kernel_write and probe_user_write Christoph Hellwig
  2020-05-19 13:44 ` [PATCH 02/20] maccess: remove various unused weak aliases Christoph Hellwig
@ 2020-05-19 13:44 ` Christoph Hellwig
  2020-05-19 13:44 ` [PATCH 04/20] maccess: clarify " Christoph Hellwig
                   ` (17 subsequent siblings)
  20 siblings, 0 replies; 33+ messages in thread
From: Christoph Hellwig @ 2020-05-19 13:44 UTC (permalink / raw)
  To: x86, Alexei Starovoitov, Daniel Borkmann, Masami Hiramatsu,
	Linus Torvalds, Andrew Morton
  Cc: linux-parisc, linux-um, netdev, bpf, linux-mm, linux-kernel

Many of the maccess routines have a copy of the kerneldoc comment
in the header.  Remove it as it is not useful and will get out of
sync sooner or later.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/linux/uaccess.h | 38 --------------------------------------
 1 file changed, 38 deletions(-)

diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index a2c606a403745..5a36a298a85f8 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -301,50 +301,12 @@ copy_struct_from_user(void *dst, size_t ksize, const void __user *src,
 	return 0;
 }
 
-/*
- * probe_kernel_read(): safely attempt to read from a location
- * @dst: pointer to the buffer that shall take the data
- * @src: address to read from
- * @size: size of the data chunk
- *
- * Safely read from address @src to the buffer at @dst.  If a kernel fault
- * happens, handle that and return -EFAULT.
- */
 extern long probe_kernel_read(void *dst, const void *src, size_t size);
 extern long probe_kernel_read_strict(void *dst, const void *src, size_t size);
 extern long __probe_kernel_read(void *dst, const void *src, size_t size);
-
-/*
- * probe_user_read(): safely attempt to read from a location in user space
- * @dst: pointer to the buffer that shall take the data
- * @src: address to read from
- * @size: size of the data chunk
- *
- * Safely read from address @src to the buffer at @dst.  If a kernel fault
- * happens, handle that and return -EFAULT.
- */
 extern long probe_user_read(void *dst, const void __user *src, size_t size);
 
-/*
- * probe_kernel_write(): safely attempt to write to a location
- * @dst: address to write to
- * @src: pointer to the data that shall be written
- * @size: size of the data chunk
- *
- * Safely write to address @dst from the buffer at @src.  If a kernel fault
- * happens, handle that and return -EFAULT.
- */
 extern long notrace probe_kernel_write(void *dst, const void *src, size_t size);
-
-/*
- * probe_user_write(): safely attempt to write to a location in user space
- * @dst: address to write to
- * @src: pointer to the data that shall be written
- * @size: size of the data chunk
- *
- * Safely write to address @dst from the buffer at @src.  If a kernel fault
- * happens, handle that and return -EFAULT.
- */
 extern long notrace probe_user_write(void __user *dst, const void *src, size_t size);
 
 extern long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count);
-- 
2.26.2


^ permalink raw reply	[flat|nested] 33+ messages in thread

* [PATCH 04/20] maccess: clarify kerneldoc comments
  2020-05-19 13:44 clean up and streamline probe_kernel_* and friends v3 Christoph Hellwig
                   ` (2 preceding siblings ...)
  2020-05-19 13:44 ` [PATCH 03/20] maccess: remove duplicate kerneldoc comments Christoph Hellwig
@ 2020-05-19 13:44 ` Christoph Hellwig
  2020-05-19 13:44 ` [PATCH 05/20] maccess: update the top of file comment Christoph Hellwig
                   ` (16 subsequent siblings)
  20 siblings, 0 replies; 33+ messages in thread
From: Christoph Hellwig @ 2020-05-19 13:44 UTC (permalink / raw)
  To: x86, Alexei Starovoitov, Daniel Borkmann, Masami Hiramatsu,
	Linus Torvalds, Andrew Morton
  Cc: linux-parisc, linux-um, netdev, bpf, linux-mm, linux-kernel

Add proper kerneldoc comments for probe_kernel_read_strict and
probe_kernel_read strncpy_from_unsafe_strict and explain the different
versus the non-strict version.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/maccess.c | 61 ++++++++++++++++++++++++++++++++++++----------------
 1 file changed, 43 insertions(+), 18 deletions(-)

diff --git a/mm/maccess.c b/mm/maccess.c
index 4e7f3b6eb05ae..747581ac50dc9 100644
--- a/mm/maccess.c
+++ b/mm/maccess.c
@@ -31,29 +31,35 @@ probe_write_common(void __user *dst, const void *src, size_t size)
 }
 
 /**
- * probe_kernel_read(): safely attempt to read from a kernel-space location
+ * probe_kernel_read(): safely attempt to read from any location
  * @dst: pointer to the buffer that shall take the data
  * @src: address to read from
  * @size: size of the data chunk
  *
- * Safely read from address @src to the buffer at @dst.  If a kernel fault
- * happens, handle that and return -EFAULT.
+ * Same as probe_kernel_read_strict() except that for architectures with
+ * not fully separated user and kernel address spaces this function also works
+ * for user address tanges.
+ *
+ * DO NOT USE THIS FUNCTION - it is broken on architectures with entirely
+ * separate kernel and user address spaces, and also a bad idea otherwise.
+ */
+long __weak probe_kernel_read(void *dst, const void *src, size_t size)
+    __attribute__((alias("__probe_kernel_read")));
+
+/**
+ * probe_kernel_read_strict(): safely attempt to read from kernel-space
+ * @dst: pointer to the buffer that shall take the data
+ * @src: address to read from
+ * @size: size of the data chunk
+ *
+ * Safely read from kernel address @src to the buffer at @dst.  If a kernel
+ * fault happens, handle that and return -EFAULT.
  *
  * We ensure that the copy_from_user is executed in atomic context so that
  * do_page_fault() doesn't attempt to take mmap_sem.  This makes
  * probe_kernel_read() suitable for use within regions where the caller
  * already holds mmap_sem, or other locks which nest inside mmap_sem.
- *
- * probe_kernel_read_strict() is the same as probe_kernel_read() except for
- * the case where architectures have non-overlapping user and kernel address
- * ranges: probe_kernel_read_strict() will additionally return -EFAULT for
- * probing memory on a user address range where probe_user_read() is supposed
- * to be used instead.
  */
-
-long __weak probe_kernel_read(void *dst, const void *src, size_t size)
-    __attribute__((alias("__probe_kernel_read")));
-
 long __weak probe_kernel_read_strict(void *dst, const void *src, size_t size)
     __attribute__((alias("__probe_kernel_read")));
 
@@ -153,15 +159,34 @@ long probe_user_write(void __user *dst, const void *src, size_t size)
  * If @count is smaller than the length of the string, copies @count-1 bytes,
  * sets the last byte of @dst buffer to NUL and returns @count.
  *
- * strncpy_from_unsafe_strict() is the same as strncpy_from_unsafe() except
- * for the case where architectures have non-overlapping user and kernel address
- * ranges: strncpy_from_unsafe_strict() will additionally return -EFAULT for
- * probing memory on a user address range where strncpy_from_unsafe_user() is
- * supposed to be used instead.
+ * Same as strncpy_from_unsafe_strict() except that for architectures with
+ * not fully separated user and kernel address spaces this function also works
+ * for user address tanges.
+ *
+ * DO NOT USE THIS FUNCTION - it is broken on architectures with entirely
+ * separate kernel and user address spaces, and also a bad idea otherwise.
  */
 long __weak strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count)
     __attribute__((alias("__strncpy_from_unsafe")));
 
+/**
+ * strncpy_from_unsafe_strict: - Copy a NUL terminated string from unsafe
+ *				 address.
+ * @dst:   Destination address, in kernel space.  This buffer must be at
+ *         least @count bytes long.
+ * @unsafe_addr: Unsafe address.
+ * @count: Maximum number of bytes to copy, including the trailing NUL.
+ *
+ * Copies a NUL-terminated string from unsafe address to kernel buffer.
+ *
+ * On success, returns the length of the string INCLUDING the trailing NUL.
+ *
+ * If access fails, returns -EFAULT (some data may have been copied
+ * and the trailing NUL added).
+ *
+ * If @count is smaller than the length of the string, copies @count-1 bytes,
+ * sets the last byte of @dst buffer to NUL and returns @count.
+ */
 long __weak strncpy_from_unsafe_strict(char *dst, const void *unsafe_addr,
 				       long count)
     __attribute__((alias("__strncpy_from_unsafe")));
-- 
2.26.2


^ permalink raw reply	[flat|nested] 33+ messages in thread

* [PATCH 05/20] maccess: update the top of file comment
  2020-05-19 13:44 clean up and streamline probe_kernel_* and friends v3 Christoph Hellwig
                   ` (3 preceding siblings ...)
  2020-05-19 13:44 ` [PATCH 04/20] maccess: clarify " Christoph Hellwig
@ 2020-05-19 13:44 ` Christoph Hellwig
  2020-05-19 13:44 ` [PATCH 06/20] maccess: rename strncpy_from_unsafe_user to strncpy_from_user_nofault Christoph Hellwig
                   ` (15 subsequent siblings)
  20 siblings, 0 replies; 33+ messages in thread
From: Christoph Hellwig @ 2020-05-19 13:44 UTC (permalink / raw)
  To: x86, Alexei Starovoitov, Daniel Borkmann, Masami Hiramatsu,
	Linus Torvalds, Andrew Morton
  Cc: linux-parisc, linux-um, netdev, bpf, linux-mm, linux-kernel

This file now also contains several helpers for accessing user memory.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/maccess.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/maccess.c b/mm/maccess.c
index 747581ac50dc9..65880ba2ca376 100644
--- a/mm/maccess.c
+++ b/mm/maccess.c
@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /*
- * Access kernel memory without faulting.
+ * Access kernel or user memory without faulting.
  */
 #include <linux/export.h>
 #include <linux/mm.h>
-- 
2.26.2


^ permalink raw reply	[flat|nested] 33+ messages in thread

* [PATCH 06/20] maccess: rename strncpy_from_unsafe_user to strncpy_from_user_nofault
  2020-05-19 13:44 clean up and streamline probe_kernel_* and friends v3 Christoph Hellwig
                   ` (4 preceding siblings ...)
  2020-05-19 13:44 ` [PATCH 05/20] maccess: update the top of file comment Christoph Hellwig
@ 2020-05-19 13:44 ` Christoph Hellwig
  2020-05-19 13:44 ` [PATCH 07/20] maccess: rename strncpy_from_unsafe_strict to strncpy_from_kernel_nofault Christoph Hellwig
                   ` (14 subsequent siblings)
  20 siblings, 0 replies; 33+ messages in thread
From: Christoph Hellwig @ 2020-05-19 13:44 UTC (permalink / raw)
  To: x86, Alexei Starovoitov, Daniel Borkmann, Masami Hiramatsu,
	Linus Torvalds, Andrew Morton
  Cc: linux-parisc, linux-um, netdev, bpf, linux-mm, linux-kernel

This matches the naming of strncpy_from_user, and also makes it more
clear what the function is supposed to do.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/linux/uaccess.h     | 4 ++--
 kernel/trace/bpf_trace.c    | 4 ++--
 kernel/trace/trace_kprobe.c | 2 +-
 mm/maccess.c                | 4 ++--
 4 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index 5a36a298a85f8..b983cb1c1216a 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -313,8 +313,8 @@ extern long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count);
 extern long strncpy_from_unsafe_strict(char *dst, const void *unsafe_addr,
 				       long count);
 extern long __strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count);
-extern long strncpy_from_unsafe_user(char *dst, const void __user *unsafe_addr,
-				     long count);
+long strncpy_from_user_nofault(char *dst, const void __user *unsafe_addr,
+		long count);
 extern long strnlen_unsafe_user(const void __user *unsafe_addr, long count);
 
 /**
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index a010edc37ee02..4e20bf1d95832 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -159,7 +159,7 @@ static const struct bpf_func_proto bpf_probe_read_user_proto = {
 BPF_CALL_3(bpf_probe_read_user_str, void *, dst, u32, size,
 	   const void __user *, unsafe_ptr)
 {
-	int ret = strncpy_from_unsafe_user(dst, unsafe_ptr, size);
+	int ret = strncpy_from_user_nofault(dst, unsafe_ptr, size);
 
 	if (unlikely(ret < 0))
 		memset(dst, 0, size);
@@ -416,7 +416,7 @@ BPF_CALL_5(bpf_trace_printk, char *, fmt, u32, fmt_size, u64, arg1,
 							   sizeof(buf));
 				break;
 			case 'u':
-				strncpy_from_unsafe_user(buf,
+				strncpy_from_user_nofault(buf,
 					(__force void __user *)unsafe_ptr,
 							 sizeof(buf));
 				break;
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 35989383ae113..d600f41fda1ca 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1268,7 +1268,7 @@ fetch_store_string_user(unsigned long addr, void *dest, void *base)
 
 	__dest = get_loc_data(dest, base);
 
-	ret = strncpy_from_unsafe_user(__dest, uaddr, maxlen);
+	ret = strncpy_from_user_nofault(__dest, uaddr, maxlen);
 	if (ret >= 0)
 		*(u32 *)dest = make_data_loc(ret, __dest - base);
 
diff --git a/mm/maccess.c b/mm/maccess.c
index 65880ba2ca376..457d8f9bf714f 100644
--- a/mm/maccess.c
+++ b/mm/maccess.c
@@ -215,7 +215,7 @@ long __strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count)
 }
 
 /**
- * strncpy_from_unsafe_user: - Copy a NUL terminated string from unsafe user
+ * strncpy_from_user_nofault: - Copy a NUL terminated string from unsafe user
  *				address.
  * @dst:   Destination address, in kernel space.  This buffer must be at
  *         least @count bytes long.
@@ -232,7 +232,7 @@ long __strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count)
  * If @count is smaller than the length of the string, copies @count-1 bytes,
  * sets the last byte of @dst buffer to NUL and returns @count.
  */
-long strncpy_from_unsafe_user(char *dst, const void __user *unsafe_addr,
+long strncpy_from_user_nofault(char *dst, const void __user *unsafe_addr,
 			      long count)
 {
 	mm_segment_t old_fs = get_fs();
-- 
2.26.2


^ permalink raw reply	[flat|nested] 33+ messages in thread

* [PATCH 07/20] maccess: rename strncpy_from_unsafe_strict to strncpy_from_kernel_nofault
  2020-05-19 13:44 clean up and streamline probe_kernel_* and friends v3 Christoph Hellwig
                   ` (5 preceding siblings ...)
  2020-05-19 13:44 ` [PATCH 06/20] maccess: rename strncpy_from_unsafe_user to strncpy_from_user_nofault Christoph Hellwig
@ 2020-05-19 13:44 ` Christoph Hellwig
  2020-05-19 13:44 ` [PATCH 08/20] maccess: rename strnlen_unsafe_user to strnlen_user_nofault Christoph Hellwig
                   ` (13 subsequent siblings)
  20 siblings, 0 replies; 33+ messages in thread
From: Christoph Hellwig @ 2020-05-19 13:44 UTC (permalink / raw)
  To: x86, Alexei Starovoitov, Daniel Borkmann, Masami Hiramatsu,
	Linus Torvalds, Andrew Morton
  Cc: linux-parisc, linux-um, netdev, bpf, linux-mm, linux-kernel

This matches the naming of strncpy_from_user_nofault, and also makes it
more clear what the function is supposed to do.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/x86/mm/maccess.c    | 2 +-
 include/linux/uaccess.h  | 4 ++--
 kernel/trace/bpf_trace.c | 4 ++--
 mm/maccess.c             | 6 +++---
 4 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/arch/x86/mm/maccess.c b/arch/x86/mm/maccess.c
index f5b85bdc0535c..62c4017a2473d 100644
--- a/arch/x86/mm/maccess.c
+++ b/arch/x86/mm/maccess.c
@@ -34,7 +34,7 @@ long probe_kernel_read_strict(void *dst, const void *src, size_t size)
 	return __probe_kernel_read(dst, src, size);
 }
 
-long strncpy_from_unsafe_strict(char *dst, const void *unsafe_addr, long count)
+long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
 {
 	if (unlikely(invalid_probe_range((unsigned long)unsafe_addr)))
 		return -EFAULT;
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index b983cb1c1216a..134ff9c1c151b 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -310,8 +310,8 @@ extern long notrace probe_kernel_write(void *dst, const void *src, size_t size);
 extern long notrace probe_user_write(void __user *dst, const void *src, size_t size);
 
 extern long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count);
-extern long strncpy_from_unsafe_strict(char *dst, const void *unsafe_addr,
-				       long count);
+long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr,
+		long count);
 extern long __strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count);
 long strncpy_from_user_nofault(char *dst, const void __user *unsafe_addr,
 		long count);
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 4e20bf1d95832..f5231ffea85b9 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -240,7 +240,7 @@ bpf_probe_read_kernel_str_common(void *dst, u32 size, const void *unsafe_ptr,
 	 * is returned that can be used for bpf_perf_event_output() et al.
 	 */
 	ret = compat ? strncpy_from_unsafe(dst, unsafe_ptr, size) :
-	      strncpy_from_unsafe_strict(dst, unsafe_ptr, size);
+	      strncpy_from_kernel_nofault(dst, unsafe_ptr, size);
 	if (unlikely(ret < 0))
 out:
 		memset(dst, 0, size);
@@ -412,7 +412,7 @@ BPF_CALL_5(bpf_trace_printk, char *, fmt, u32, fmt_size, u64, arg1,
 				break;
 #endif
 			case 'k':
-				strncpy_from_unsafe_strict(buf, unsafe_ptr,
+				strncpy_from_kernel_nofault(buf, unsafe_ptr,
 							   sizeof(buf));
 				break;
 			case 'u':
diff --git a/mm/maccess.c b/mm/maccess.c
index 457d8f9bf714f..c8748c2809096 100644
--- a/mm/maccess.c
+++ b/mm/maccess.c
@@ -159,7 +159,7 @@ long probe_user_write(void __user *dst, const void *src, size_t size)
  * If @count is smaller than the length of the string, copies @count-1 bytes,
  * sets the last byte of @dst buffer to NUL and returns @count.
  *
- * Same as strncpy_from_unsafe_strict() except that for architectures with
+ * Same as strncpy_from_kernel_nofault() except that for architectures with
  * not fully separated user and kernel address spaces this function also works
  * for user address tanges.
  *
@@ -170,7 +170,7 @@ long __weak strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count)
     __attribute__((alias("__strncpy_from_unsafe")));
 
 /**
- * strncpy_from_unsafe_strict: - Copy a NUL terminated string from unsafe
+ * strncpy_from_kernel_nofault: - Copy a NUL terminated string from unsafe
  *				 address.
  * @dst:   Destination address, in kernel space.  This buffer must be at
  *         least @count bytes long.
@@ -187,7 +187,7 @@ long __weak strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count)
  * If @count is smaller than the length of the string, copies @count-1 bytes,
  * sets the last byte of @dst buffer to NUL and returns @count.
  */
-long __weak strncpy_from_unsafe_strict(char *dst, const void *unsafe_addr,
+long __weak strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr,
 				       long count)
     __attribute__((alias("__strncpy_from_unsafe")));
 
-- 
2.26.2


^ permalink raw reply	[flat|nested] 33+ messages in thread

* [PATCH 08/20] maccess: rename strnlen_unsafe_user to strnlen_user_nofault
  2020-05-19 13:44 clean up and streamline probe_kernel_* and friends v3 Christoph Hellwig
                   ` (6 preceding siblings ...)
  2020-05-19 13:44 ` [PATCH 07/20] maccess: rename strncpy_from_unsafe_strict to strncpy_from_kernel_nofault Christoph Hellwig
@ 2020-05-19 13:44 ` Christoph Hellwig
  2020-05-19 13:44 ` [PATCH 09/20] maccess: remove probe_read_common and probe_write_common Christoph Hellwig
                   ` (12 subsequent siblings)
  20 siblings, 0 replies; 33+ messages in thread
From: Christoph Hellwig @ 2020-05-19 13:44 UTC (permalink / raw)
  To: x86, Alexei Starovoitov, Daniel Borkmann, Masami Hiramatsu,
	Linus Torvalds, Andrew Morton
  Cc: linux-parisc, linux-um, netdev, bpf, linux-mm, linux-kernel

This matches the naming of strnlen_user, and also makes it more clear
what the function is supposed to do.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/linux/uaccess.h     | 2 +-
 kernel/trace/trace_kprobe.c | 2 +-
 mm/maccess.c                | 4 ++--
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index 134ff9c1c151b..d8366f8468664 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -315,7 +315,7 @@ long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr,
 extern long __strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count);
 long strncpy_from_user_nofault(char *dst, const void __user *unsafe_addr,
 		long count);
-extern long strnlen_unsafe_user(const void __user *unsafe_addr, long count);
+long strnlen_user_nofault(const void __user *unsafe_addr, long count);
 
 /**
  * probe_kernel_address(): safely attempt to read from a location
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index d600f41fda1ca..4325f9e7fadaa 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1221,7 +1221,7 @@ fetch_store_strlen_user(unsigned long addr)
 {
 	const void __user *uaddr =  (__force const void __user *)addr;
 
-	return strnlen_unsafe_user(uaddr, MAX_STRING_SIZE);
+	return strnlen_user_nofault(uaddr, MAX_STRING_SIZE);
 }
 
 /*
diff --git a/mm/maccess.c b/mm/maccess.c
index c8748c2809096..e783ebfccd542 100644
--- a/mm/maccess.c
+++ b/mm/maccess.c
@@ -258,7 +258,7 @@ long strncpy_from_user_nofault(char *dst, const void __user *unsafe_addr,
 }
 
 /**
- * strnlen_unsafe_user: - Get the size of a user string INCLUDING final NUL.
+ * strnlen_user_nofault: - Get the size of a user string INCLUDING final NUL.
  * @unsafe_addr: The string to measure.
  * @count: Maximum count (including NUL)
  *
@@ -273,7 +273,7 @@ long strncpy_from_user_nofault(char *dst, const void __user *unsafe_addr,
  * Unlike strnlen_user, this can be used from IRQ handler etc. because
  * it disables pagefaults.
  */
-long strnlen_unsafe_user(const void __user *unsafe_addr, long count)
+long strnlen_user_nofault(const void __user *unsafe_addr, long count)
 {
 	mm_segment_t old_fs = get_fs();
 	int ret;
-- 
2.26.2


^ permalink raw reply	[flat|nested] 33+ messages in thread

* [PATCH 09/20] maccess: remove probe_read_common and probe_write_common
  2020-05-19 13:44 clean up and streamline probe_kernel_* and friends v3 Christoph Hellwig
                   ` (7 preceding siblings ...)
  2020-05-19 13:44 ` [PATCH 08/20] maccess: rename strnlen_unsafe_user to strnlen_user_nofault Christoph Hellwig
@ 2020-05-19 13:44 ` Christoph Hellwig
  2020-05-19 13:44 ` [PATCH 10/20] maccess: unify the probe kernel arch hooks Christoph Hellwig
                   ` (11 subsequent siblings)
  20 siblings, 0 replies; 33+ messages in thread
From: Christoph Hellwig @ 2020-05-19 13:44 UTC (permalink / raw)
  To: x86, Alexei Starovoitov, Daniel Borkmann, Masami Hiramatsu,
	Linus Torvalds, Andrew Morton
  Cc: linux-parisc, linux-um, netdev, bpf, linux-mm, linux-kernel

Each of the helpers has just two callers, which also different in
dealing with kernel or userspace pointers.  Just open code the logic
in the callers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/maccess.c | 63 ++++++++++++++++++++++++----------------------------
 1 file changed, 29 insertions(+), 34 deletions(-)

diff --git a/mm/maccess.c b/mm/maccess.c
index e783ebfccd542..31cf6604e7fff 100644
--- a/mm/maccess.c
+++ b/mm/maccess.c
@@ -6,30 +6,6 @@
 #include <linux/mm.h>
 #include <linux/uaccess.h>
 
-static __always_inline long
-probe_read_common(void *dst, const void __user *src, size_t size)
-{
-	long ret;
-
-	pagefault_disable();
-	ret = __copy_from_user_inatomic(dst, src, size);
-	pagefault_enable();
-
-	return ret ? -EFAULT : 0;
-}
-
-static __always_inline long
-probe_write_common(void __user *dst, const void *src, size_t size)
-{
-	long ret;
-
-	pagefault_disable();
-	ret = __copy_to_user_inatomic(dst, src, size);
-	pagefault_enable();
-
-	return ret ? -EFAULT : 0;
-}
-
 /**
  * probe_kernel_read(): safely attempt to read from any location
  * @dst: pointer to the buffer that shall take the data
@@ -69,10 +45,15 @@ long __probe_kernel_read(void *dst, const void *src, size_t size)
 	mm_segment_t old_fs = get_fs();
 
 	set_fs(KERNEL_DS);
-	ret = probe_read_common(dst, (__force const void __user *)src, size);
+	pagefault_disable();
+	ret = __copy_from_user_inatomic(dst, (__force const void __user *)src,
+			size);
+	pagefault_enable();
 	set_fs(old_fs);
 
-	return ret;
+	if (ret)
+		return -EFAULT;
+	return 0;
 }
 EXPORT_SYMBOL_GPL(probe_kernel_read);
 
@@ -91,11 +72,16 @@ long probe_user_read(void *dst, const void __user *src, size_t size)
 	mm_segment_t old_fs = get_fs();
 
 	set_fs(USER_DS);
-	if (access_ok(src, size))
-		ret = probe_read_common(dst, src, size);
+	if (access_ok(src, size)) {
+		pagefault_disable();
+		ret = __copy_from_user_inatomic(dst, src, size);
+		pagefault_enable();
+	}
 	set_fs(old_fs);
 
-	return ret;
+	if (ret)
+		return -EFAULT;
+	return 0;
 }
 EXPORT_SYMBOL_GPL(probe_user_read);
 
@@ -114,10 +100,14 @@ long probe_kernel_write(void *dst, const void *src, size_t size)
 	mm_segment_t old_fs = get_fs();
 
 	set_fs(KERNEL_DS);
-	ret = probe_write_common((__force void __user *)dst, src, size);
+	pagefault_disable();
+	ret = __copy_to_user_inatomic((__force void __user *)dst, src, size);
+	pagefault_enable();
 	set_fs(old_fs);
 
-	return ret;
+	if (ret)
+		return -EFAULT;
+	return 0;
 }
 
 /**
@@ -135,11 +125,16 @@ long probe_user_write(void __user *dst, const void *src, size_t size)
 	mm_segment_t old_fs = get_fs();
 
 	set_fs(USER_DS);
-	if (access_ok(dst, size))
-		ret = probe_write_common(dst, src, size);
+	if (access_ok(dst, size)) {
+		pagefault_disable();
+		ret = __copy_to_user_inatomic(dst, src, size);
+		pagefault_enable();
+	}
 	set_fs(old_fs);
 
-	return ret;
+	if (ret)
+		return -EFAULT;
+	return 0;
 }
 
 /**
-- 
2.26.2


^ permalink raw reply	[flat|nested] 33+ messages in thread

* [PATCH 10/20] maccess: unify the probe kernel arch hooks
  2020-05-19 13:44 clean up and streamline probe_kernel_* and friends v3 Christoph Hellwig
                   ` (8 preceding siblings ...)
  2020-05-19 13:44 ` [PATCH 09/20] maccess: remove probe_read_common and probe_write_common Christoph Hellwig
@ 2020-05-19 13:44 ` Christoph Hellwig
  2020-05-19 13:44 ` [PATCH 11/20] bpf: factor out a bpf_trace_copy_string helper Christoph Hellwig
                   ` (10 subsequent siblings)
  20 siblings, 0 replies; 33+ messages in thread
From: Christoph Hellwig @ 2020-05-19 13:44 UTC (permalink / raw)
  To: x86, Alexei Starovoitov, Daniel Borkmann, Masami Hiramatsu,
	Linus Torvalds, Andrew Morton
  Cc: linux-parisc, linux-um, netdev, bpf, linux-mm, linux-kernel

Currently architectures have to override every routine that probes
kernel memory, which includes a pure read and strcpy, both in strict
and not strict variants.  Just provide a single arch hooks instead to
make sure all architectures cover all the cases.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/parisc/lib/memcpy.c | 13 ++++-------
 arch/um/kernel/maccess.c | 11 ++++-----
 arch/x86/mm/maccess.c    | 18 ++++-----------
 include/linux/uaccess.h  |  6 +++--
 mm/maccess.c             | 49 ++++++++++++++++++++++++++++++----------
 5 files changed, 56 insertions(+), 41 deletions(-)

diff --git a/arch/parisc/lib/memcpy.c b/arch/parisc/lib/memcpy.c
index beceaab34ecb7..5ef648bd33119 100644
--- a/arch/parisc/lib/memcpy.c
+++ b/arch/parisc/lib/memcpy.c
@@ -57,14 +57,11 @@ void * memcpy(void * dst,const void *src, size_t count)
 EXPORT_SYMBOL(raw_copy_in_user);
 EXPORT_SYMBOL(memcpy);
 
-long probe_kernel_read(void *dst, const void *src, size_t size)
+bool probe_kernel_read_allowed(void *dst, const void *unsafe_src, size_t size,
+		bool strict)
 {
-	unsigned long addr = (unsigned long)src;
-
-	if (addr < PAGE_SIZE)
-		return -EFAULT;
-
+	if ((unsigned long)unsafe_src < PAGE_SIZE)
+		return false;
 	/* check for I/O space F_EXTEND(0xfff00000) access as well? */
-
-	return __probe_kernel_read(dst, src, size);
+	return true;
 }
diff --git a/arch/um/kernel/maccess.c b/arch/um/kernel/maccess.c
index 67b2e0fa92bba..90a1bec923158 100644
--- a/arch/um/kernel/maccess.c
+++ b/arch/um/kernel/maccess.c
@@ -7,15 +7,14 @@
 #include <linux/kernel.h>
 #include <os.h>
 
-long probe_kernel_read(void *dst, const void *src, size_t size)
+bool probe_kernel_read_allowed(void *dst, const void *src, size_t size,
+		bool strict)
 {
 	void *psrc = (void *)rounddown((unsigned long)src, PAGE_SIZE);
 
 	if ((unsigned long)src < PAGE_SIZE || size <= 0)
-		return -EFAULT;
-
+		return false;
 	if (os_mincore(psrc, size + src - psrc) <= 0)
-		return -EFAULT;
-
-	return __probe_kernel_read(dst, src, size);
+		return false;
+	return true;
 }
diff --git a/arch/x86/mm/maccess.c b/arch/x86/mm/maccess.c
index 62c4017a2473d..5c323ab187b27 100644
--- a/arch/x86/mm/maccess.c
+++ b/arch/x86/mm/maccess.c
@@ -26,18 +26,10 @@ static __always_inline bool invalid_probe_range(u64 vaddr)
 }
 #endif
 
-long probe_kernel_read_strict(void *dst, const void *src, size_t size)
+bool probe_kernel_read_allowed(void *dst, const void *unsafe_src, size_t size,
+		bool strict)
 {
-	if (unlikely(invalid_probe_range((unsigned long)src)))
-		return -EFAULT;
-
-	return __probe_kernel_read(dst, src, size);
-}
-
-long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
-{
-	if (unlikely(invalid_probe_range((unsigned long)unsafe_addr)))
-		return -EFAULT;
-
-	return __strncpy_from_unsafe(dst, unsafe_addr, count);
+	if (!strict)
+		return true;
+	return !invalid_probe_range((unsigned long)unsafe_src);
 }
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index d8366f8468664..7cfc10eb09c60 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -301,9 +301,11 @@ copy_struct_from_user(void *dst, size_t ksize, const void __user *src,
 	return 0;
 }
 
+bool probe_kernel_read_allowed(void *dst, const void *unsafe_src,
+		size_t size, bool strict);
+
 extern long probe_kernel_read(void *dst, const void *src, size_t size);
 extern long probe_kernel_read_strict(void *dst, const void *src, size_t size);
-extern long __probe_kernel_read(void *dst, const void *src, size_t size);
 extern long probe_user_read(void *dst, const void __user *src, size_t size);
 
 extern long notrace probe_kernel_write(void *dst, const void *src, size_t size);
@@ -312,7 +314,7 @@ extern long notrace probe_user_write(void __user *dst, const void *src, size_t s
 extern long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count);
 long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr,
 		long count);
-extern long __strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count);
+
 long strncpy_from_user_nofault(char *dst, const void __user *unsafe_addr,
 		long count);
 long strnlen_user_nofault(const void __user *unsafe_addr, long count);
diff --git a/mm/maccess.c b/mm/maccess.c
index 31cf6604e7fff..483a933b7d241 100644
--- a/mm/maccess.c
+++ b/mm/maccess.c
@@ -6,6 +6,17 @@
 #include <linux/mm.h>
 #include <linux/uaccess.h>
 
+static long __probe_kernel_read(void *dst, const void *src, size_t size,
+		bool strict);
+static long __strncpy_from_unsafe(char *dst, const void *unsafe_addr,
+		long count, bool strict);
+
+bool __weak probe_kernel_read_allowed(void *dst, const void *unsafe_src,
+		size_t size, bool strict)
+{
+	return true;
+}
+
 /**
  * probe_kernel_read(): safely attempt to read from any location
  * @dst: pointer to the buffer that shall take the data
@@ -19,8 +30,11 @@
  * DO NOT USE THIS FUNCTION - it is broken on architectures with entirely
  * separate kernel and user address spaces, and also a bad idea otherwise.
  */
-long __weak probe_kernel_read(void *dst, const void *src, size_t size)
-    __attribute__((alias("__probe_kernel_read")));
+long probe_kernel_read(void *dst, const void *src, size_t size)
+{
+	return __probe_kernel_read(dst, src, size, false);
+}
+EXPORT_SYMBOL_GPL(probe_kernel_read);
 
 /**
  * probe_kernel_read_strict(): safely attempt to read from kernel-space
@@ -36,14 +50,20 @@ long __weak probe_kernel_read(void *dst, const void *src, size_t size)
  * probe_kernel_read() suitable for use within regions where the caller
  * already holds mmap_sem, or other locks which nest inside mmap_sem.
  */
-long __weak probe_kernel_read_strict(void *dst, const void *src, size_t size)
-    __attribute__((alias("__probe_kernel_read")));
+long probe_kernel_read_strict(void *dst, const void *src, size_t size)
+{
+	return __probe_kernel_read(dst, src, size, true);
+}
 
-long __probe_kernel_read(void *dst, const void *src, size_t size)
+static long __probe_kernel_read(void *dst, const void *src, size_t size,
+		bool strict)
 {
 	long ret;
 	mm_segment_t old_fs = get_fs();
 
+	if (!probe_kernel_read_allowed(dst, src, size, strict))
+		return -EFAULT;
+
 	set_fs(KERNEL_DS);
 	pagefault_disable();
 	ret = __copy_from_user_inatomic(dst, (__force const void __user *)src,
@@ -55,7 +75,6 @@ long __probe_kernel_read(void *dst, const void *src, size_t size)
 		return -EFAULT;
 	return 0;
 }
-EXPORT_SYMBOL_GPL(probe_kernel_read);
 
 /**
  * probe_user_read(): safely attempt to read from a user-space location
@@ -161,8 +180,10 @@ long probe_user_write(void __user *dst, const void *src, size_t size)
  * DO NOT USE THIS FUNCTION - it is broken on architectures with entirely
  * separate kernel and user address spaces, and also a bad idea otherwise.
  */
-long __weak strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count)
-    __attribute__((alias("__strncpy_from_unsafe")));
+long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count)
+{
+	return __strncpy_from_unsafe(dst, unsafe_addr, count, false);
+}
 
 /**
  * strncpy_from_kernel_nofault: - Copy a NUL terminated string from unsafe
@@ -182,11 +203,13 @@ long __weak strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count)
  * If @count is smaller than the length of the string, copies @count-1 bytes,
  * sets the last byte of @dst buffer to NUL and returns @count.
  */
-long __weak strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr,
-				       long count)
-    __attribute__((alias("__strncpy_from_unsafe")));
+long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
+{
+	return __strncpy_from_unsafe(dst, unsafe_addr, count, true);
+}
 
-long __strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count)
+static long __strncpy_from_unsafe(char *dst, const void *unsafe_addr,
+		long count, bool strict)
 {
 	mm_segment_t old_fs = get_fs();
 	const void *src = unsafe_addr;
@@ -194,6 +217,8 @@ long __strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count)
 
 	if (unlikely(count <= 0))
 		return 0;
+	if (!probe_kernel_read_allowed(dst, unsafe_addr, count, strict))
+		return -EFAULT;
 
 	set_fs(KERNEL_DS);
 	pagefault_disable();
-- 
2.26.2


^ permalink raw reply	[flat|nested] 33+ messages in thread

* [PATCH 11/20] bpf: factor out a bpf_trace_copy_string helper
  2020-05-19 13:44 clean up and streamline probe_kernel_* and friends v3 Christoph Hellwig
                   ` (9 preceding siblings ...)
  2020-05-19 13:44 ` [PATCH 10/20] maccess: unify the probe kernel arch hooks Christoph Hellwig
@ 2020-05-19 13:44 ` Christoph Hellwig
  2020-05-19 16:07   ` Linus Torvalds
  2020-05-19 13:44 ` [PATCH 12/20] maccess: remove strncpy_from_unsafe Christoph Hellwig
                   ` (9 subsequent siblings)
  20 siblings, 1 reply; 33+ messages in thread
From: Christoph Hellwig @ 2020-05-19 13:44 UTC (permalink / raw)
  To: x86, Alexei Starovoitov, Daniel Borkmann, Masami Hiramatsu,
	Linus Torvalds, Andrew Morton
  Cc: linux-parisc, linux-um, netdev, bpf, linux-mm, linux-kernel

Split out a helper to do the fault free access to the string pointer
to get it out of a crazy indentation level.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 kernel/trace/bpf_trace.c | 42 +++++++++++++++++++++++-----------------
 1 file changed, 24 insertions(+), 18 deletions(-)

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index f5231ffea85b9..9d4080590f711 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -321,6 +321,28 @@ static const struct bpf_func_proto *bpf_get_probe_write_proto(void)
 	return &bpf_probe_write_user_proto;
 }
 
+static void bpf_trace_copy_string(char *buf, void *unsafe_ptr, char fmt_ptype,
+		size_t bufsz)
+{
+	void __user *user_ptr = (__force void __user *)unsafe_ptr;
+
+	buf[0] = 0;
+
+	switch (fmt_ptype) {
+	case 's':
+#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
+		strncpy_from_unsafe(buf, unsafe_ptr, bufsz);
+		break;
+#endif
+	case 'k':
+		strncpy_from_kernel_nofault(buf, unsafe_ptr, bufsz);
+		break;
+	case 'u':
+		strncpy_from_user_nofault(buf, user_ptr, bufsz);
+		break;
+	}
+}
+
 /*
  * Only limited trace_printk() conversion specifiers allowed:
  * %d %i %u %x %ld %li %lu %lx %lld %lli %llu %llx %p %pks %pus %s
@@ -403,24 +425,8 @@ BPF_CALL_5(bpf_trace_printk, char *, fmt, u32, fmt_size, u64, arg1,
 				break;
 			}
 
-			buf[0] = 0;
-			switch (fmt_ptype) {
-			case 's':
-#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
-				strncpy_from_unsafe(buf, unsafe_ptr,
-						    sizeof(buf));
-				break;
-#endif
-			case 'k':
-				strncpy_from_kernel_nofault(buf, unsafe_ptr,
-							   sizeof(buf));
-				break;
-			case 'u':
-				strncpy_from_user_nofault(buf,
-					(__force void __user *)unsafe_ptr,
-							 sizeof(buf));
-				break;
-			}
+			bpf_trace_copy_string(buf, unsafe_ptr, fmt_ptype,
+					sizeof(buf));
 			goto fmt_next;
 		}
 
-- 
2.26.2


^ permalink raw reply	[flat|nested] 33+ messages in thread

* [PATCH 12/20] maccess: remove strncpy_from_unsafe
  2020-05-19 13:44 clean up and streamline probe_kernel_* and friends v3 Christoph Hellwig
                   ` (10 preceding siblings ...)
  2020-05-19 13:44 ` [PATCH 11/20] bpf: factor out a bpf_trace_copy_string helper Christoph Hellwig
@ 2020-05-19 13:44 ` Christoph Hellwig
  2020-05-19 16:25   ` Linus Torvalds
  2020-05-19 13:44 ` [PATCH 13/20] maccess: always use strict semantics for probe_kernel_read Christoph Hellwig
                   ` (8 subsequent siblings)
  20 siblings, 1 reply; 33+ messages in thread
From: Christoph Hellwig @ 2020-05-19 13:44 UTC (permalink / raw)
  To: x86, Alexei Starovoitov, Daniel Borkmann, Masami Hiramatsu,
	Linus Torvalds, Andrew Morton
  Cc: linux-parisc, linux-um, netdev, bpf, linux-mm, linux-kernel

All three callers really should try the explicit kernel or user copies.
Switch them to try a user copy if the address is smaller than TASK_SIZE
and the architecture has non-overlapping address ranges, or a kernel copy
otherwise.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/linux/uaccess.h     |  1 -
 kernel/trace/bpf_trace.c    | 23 +++++++++++++++-------
 kernel/trace/trace_kprobe.c |  8 +++++++-
 mm/maccess.c                | 39 +------------------------------------
 4 files changed, 24 insertions(+), 47 deletions(-)

diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index 7cfc10eb09c60..28944a14e0534 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -311,7 +311,6 @@ extern long probe_user_read(void *dst, const void __user *src, size_t size);
 extern long notrace probe_kernel_write(void *dst, const void *src, size_t size);
 extern long notrace probe_user_write(void __user *dst, const void *src, size_t size);
 
-extern long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count);
 long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr,
 		long count);
 
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 9d4080590f711..bab9b8a175cb0 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -226,12 +226,14 @@ static __always_inline int
 bpf_probe_read_kernel_str_common(void *dst, u32 size, const void *unsafe_ptr,
 				 const bool compat)
 {
+	const void __user *user_ptr = (__force const void __user *)unsafe_ptr;
 	int ret = security_locked_down(LOCKDOWN_BPF_READ);
 
 	if (unlikely(ret < 0))
-		goto out;
+		goto fail;
+
 	/*
-	 * The strncpy_from_unsafe_*() call will likely not fill the entire
+	 * The strncpy_from_*_nofault() calls will likely not fill the entire
 	 * buffer, but that's okay in this circumstance as we're probing
 	 * arbitrary memory anyway similar to bpf_probe_read_*() and might
 	 * as well probe the stack. Thus, memory is explicitly cleared
@@ -239,11 +241,17 @@ bpf_probe_read_kernel_str_common(void *dst, u32 size, const void *unsafe_ptr,
 	 * code altogether don't copy garbage; otherwise length of string
 	 * is returned that can be used for bpf_perf_event_output() et al.
 	 */
-	ret = compat ? strncpy_from_unsafe(dst, unsafe_ptr, size) :
-	      strncpy_from_kernel_nofault(dst, unsafe_ptr, size);
+	if (IS_ENABLED(CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE) &&
+	    compat && (unsigned long)unsafe_ptr < TASK_SIZE)
+		ret = strncpy_from_user_nofault(dst, user_ptr, size);
+	else
+		ret = strncpy_from_kernel_nofault(dst, unsafe_ptr, size);
 	if (unlikely(ret < 0))
-out:
-		memset(dst, 0, size);
+		goto fail;
+
+	return 0;
+fail:
+	memset(dst, 0, size);
 	return ret;
 }
 
@@ -331,7 +339,8 @@ static void bpf_trace_copy_string(char *buf, void *unsafe_ptr, char fmt_ptype,
 	switch (fmt_ptype) {
 	case 's':
 #ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
-		strncpy_from_unsafe(buf, unsafe_ptr, bufsz);
+		if (strncpy_from_kernel_nofault(buf, unsafe_ptr, bufsz) == 0)
+			strncpy_from_user_nofault(buf, user_ptr, bufsz);
 		break;
 #endif
 	case 'k':
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 4325f9e7fadaa..2f6737cc53e6c 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1244,7 +1244,13 @@ fetch_store_string(unsigned long addr, void *dest, void *base)
 	 * Try to get string again, since the string can be changed while
 	 * probing.
 	 */
-	ret = strncpy_from_unsafe(__dest, (void *)addr, maxlen);
+	if (IS_ENABLED(CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE) &&
+	    addr < TASK_SIZE) {
+		ret = strncpy_from_user_nofault(__dest, (void __user *)addr,
+				maxlen);
+	} else {
+		ret = strncpy_from_kernel_nofault(__dest, (void *)addr, maxlen);
+	}
 	if (ret >= 0)
 		*(u32 *)dest = make_data_loc(ret, __dest - base);
 
diff --git a/mm/maccess.c b/mm/maccess.c
index 483a933b7d241..3d85e48013e6b 100644
--- a/mm/maccess.c
+++ b/mm/maccess.c
@@ -8,8 +8,6 @@
 
 static long __probe_kernel_read(void *dst, const void *src, size_t size,
 		bool strict);
-static long __strncpy_from_unsafe(char *dst, const void *unsafe_addr,
-		long count, bool strict);
 
 bool __weak probe_kernel_read_allowed(void *dst, const void *unsafe_src,
 		size_t size, bool strict)
@@ -156,35 +154,6 @@ long probe_user_write(void __user *dst, const void *src, size_t size)
 	return 0;
 }
 
-/**
- * strncpy_from_unsafe: - Copy a NUL terminated string from unsafe address.
- * @dst:   Destination address, in kernel space.  This buffer must be at
- *         least @count bytes long.
- * @unsafe_addr: Unsafe address.
- * @count: Maximum number of bytes to copy, including the trailing NUL.
- *
- * Copies a NUL-terminated string from unsafe address to kernel buffer.
- *
- * On success, returns the length of the string INCLUDING the trailing NUL.
- *
- * If access fails, returns -EFAULT (some data may have been copied
- * and the trailing NUL added).
- *
- * If @count is smaller than the length of the string, copies @count-1 bytes,
- * sets the last byte of @dst buffer to NUL and returns @count.
- *
- * Same as strncpy_from_kernel_nofault() except that for architectures with
- * not fully separated user and kernel address spaces this function also works
- * for user address tanges.
- *
- * DO NOT USE THIS FUNCTION - it is broken on architectures with entirely
- * separate kernel and user address spaces, and also a bad idea otherwise.
- */
-long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count)
-{
-	return __strncpy_from_unsafe(dst, unsafe_addr, count, false);
-}
-
 /**
  * strncpy_from_kernel_nofault: - Copy a NUL terminated string from unsafe
  *				 address.
@@ -204,12 +173,6 @@ long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count)
  * sets the last byte of @dst buffer to NUL and returns @count.
  */
 long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
-{
-	return __strncpy_from_unsafe(dst, unsafe_addr, count, true);
-}
-
-static long __strncpy_from_unsafe(char *dst, const void *unsafe_addr,
-		long count, bool strict)
 {
 	mm_segment_t old_fs = get_fs();
 	const void *src = unsafe_addr;
@@ -217,7 +180,7 @@ static long __strncpy_from_unsafe(char *dst, const void *unsafe_addr,
 
 	if (unlikely(count <= 0))
 		return 0;
-	if (!probe_kernel_read_allowed(dst, unsafe_addr, count, strict))
+	if (!probe_kernel_read_allowed(dst, unsafe_addr, count, true))
 		return -EFAULT;
 
 	set_fs(KERNEL_DS);
-- 
2.26.2


^ permalink raw reply	[flat|nested] 33+ messages in thread

* [PATCH 13/20] maccess: always use strict semantics for probe_kernel_read
  2020-05-19 13:44 clean up and streamline probe_kernel_* and friends v3 Christoph Hellwig
                   ` (11 preceding siblings ...)
  2020-05-19 13:44 ` [PATCH 12/20] maccess: remove strncpy_from_unsafe Christoph Hellwig
@ 2020-05-19 13:44 ` Christoph Hellwig
  2020-05-19 16:33   ` Linus Torvalds
  2020-05-20 11:11   ` Masami Hiramatsu
  2020-05-19 13:44 ` [PATCH 14/20] maccess: move user access routines together Christoph Hellwig
                   ` (7 subsequent siblings)
  20 siblings, 2 replies; 33+ messages in thread
From: Christoph Hellwig @ 2020-05-19 13:44 UTC (permalink / raw)
  To: x86, Alexei Starovoitov, Daniel Borkmann, Masami Hiramatsu,
	Linus Torvalds, Andrew Morton
  Cc: linux-parisc, linux-um, netdev, bpf, linux-mm, linux-kernel

Except for historical confusion in the kprobes/uprobes and bpf tracers,
there is no good reason to ever allow user memory accesses from
probe_kernel_read.  Switch probe_kernel_read to only read from kernel
memory itself, and try to read user memory in the tracers only if
the address is smaller than TASK_SIZE, and the architecture has
non-overlapping address ranges.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/parisc/lib/memcpy.c    |  3 +--
 arch/um/kernel/maccess.c    |  3 +--
 arch/x86/mm/maccess.c       |  5 +----
 include/linux/uaccess.h     |  4 +---
 kernel/trace/bpf_trace.c    | 18 ++++++++++++-----
 kernel/trace/trace_kprobe.c | 14 ++++++++++++-
 mm/maccess.c                | 39 ++++++-------------------------------
 7 files changed, 36 insertions(+), 50 deletions(-)

diff --git a/arch/parisc/lib/memcpy.c b/arch/parisc/lib/memcpy.c
index 5ef648bd33119..9fe662b3b5604 100644
--- a/arch/parisc/lib/memcpy.c
+++ b/arch/parisc/lib/memcpy.c
@@ -57,8 +57,7 @@ void * memcpy(void * dst,const void *src, size_t count)
 EXPORT_SYMBOL(raw_copy_in_user);
 EXPORT_SYMBOL(memcpy);
 
-bool probe_kernel_read_allowed(void *dst, const void *unsafe_src, size_t size,
-		bool strict)
+bool probe_kernel_read_allowed(void *dst, const void *unsafe_src, size_t size)
 {
 	if ((unsigned long)unsafe_src < PAGE_SIZE)
 		return false;
diff --git a/arch/um/kernel/maccess.c b/arch/um/kernel/maccess.c
index 90a1bec923158..734f3d7e57c0f 100644
--- a/arch/um/kernel/maccess.c
+++ b/arch/um/kernel/maccess.c
@@ -7,8 +7,7 @@
 #include <linux/kernel.h>
 #include <os.h>
 
-bool probe_kernel_read_allowed(void *dst, const void *src, size_t size,
-		bool strict)
+bool probe_kernel_read_allowed(void *dst, const void *src, size_t size)
 {
 	void *psrc = (void *)rounddown((unsigned long)src, PAGE_SIZE);
 
diff --git a/arch/x86/mm/maccess.c b/arch/x86/mm/maccess.c
index 5c323ab187b27..a1bd81677aa72 100644
--- a/arch/x86/mm/maccess.c
+++ b/arch/x86/mm/maccess.c
@@ -26,10 +26,7 @@ static __always_inline bool invalid_probe_range(u64 vaddr)
 }
 #endif
 
-bool probe_kernel_read_allowed(void *dst, const void *unsafe_src, size_t size,
-		bool strict)
+bool probe_kernel_read_allowed(void *dst, const void *unsafe_src, size_t size)
 {
-	if (!strict)
-		return true;
 	return !invalid_probe_range((unsigned long)unsafe_src);
 }
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index 28944a14e0534..78e0ff8641559 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -301,11 +301,9 @@ copy_struct_from_user(void *dst, size_t ksize, const void __user *src,
 	return 0;
 }
 
-bool probe_kernel_read_allowed(void *dst, const void *unsafe_src,
-		size_t size, bool strict);
+bool probe_kernel_read_allowed(void *dst, const void *unsafe_src, size_t size);
 
 extern long probe_kernel_read(void *dst, const void *src, size_t size);
-extern long probe_kernel_read_strict(void *dst, const void *src, size_t size);
 extern long probe_user_read(void *dst, const void __user *src, size_t size);
 
 extern long notrace probe_kernel_write(void *dst, const void *src, size_t size);
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index bab9b8a175cb0..c6007d9a987d5 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -180,15 +180,23 @@ static __always_inline int
 bpf_probe_read_kernel_common(void *dst, u32 size, const void *unsafe_ptr,
 			     const bool compat)
 {
+	const void __user *user_ptr = (__force const void __user *)unsafe_ptr;
 	int ret = security_locked_down(LOCKDOWN_BPF_READ);
 
 	if (unlikely(ret < 0))
-		goto out;
-	ret = compat ? probe_kernel_read(dst, unsafe_ptr, size) :
-	      probe_kernel_read_strict(dst, unsafe_ptr, size);
+		goto fail;
+
+	if (IS_ENABLED(CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE) &&
+	    compat && (unsigned long)unsafe_ptr < TASK_SIZE)
+		ret = probe_user_read(dst, user_ptr, size);
+	else
+		ret = probe_kernel_read(dst, unsafe_ptr, size);
 	if (unlikely(ret < 0))
-out:
-		memset(dst, 0, size);
+		goto fail;
+
+	return 0;
+fail:
+	memset(dst, 0, size);
 	return ret;
 }
 
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 2f6737cc53e6c..82da20e712507 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1208,7 +1208,13 @@ fetch_store_strlen(unsigned long addr)
 	u8 c;
 
 	do {
-		ret = probe_kernel_read(&c, (u8 *)addr + len, 1);
+		if (IS_ENABLED(CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE) &&
+		    (unsigned long)addr < TASK_SIZE) {
+			ret = probe_user_read(&c,
+				(__force u8 __user *)addr + len, 1);
+		} else {
+			ret = probe_kernel_read(&c, (u8 *)addr + len, 1);
+		}
 		len++;
 	} while (c && ret == 0 && len < MAX_STRING_SIZE);
 
@@ -1284,6 +1290,12 @@ fetch_store_string_user(unsigned long addr, void *dest, void *base)
 static nokprobe_inline int
 probe_mem_read(void *dest, void *src, size_t size)
 {
+	if (IS_ENABLED(CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE) &&
+	    (unsigned long)src < TASK_SIZE) {
+		return probe_user_read(dest, (__force const void __user *)src,
+				size);
+	}
+
 	return probe_kernel_read(dest, src, size);
 }
 
diff --git a/mm/maccess.c b/mm/maccess.c
index 3d85e48013e6b..05c44d490b4e3 100644
--- a/mm/maccess.c
+++ b/mm/maccess.c
@@ -6,36 +6,14 @@
 #include <linux/mm.h>
 #include <linux/uaccess.h>
 
-static long __probe_kernel_read(void *dst, const void *src, size_t size,
-		bool strict);
-
 bool __weak probe_kernel_read_allowed(void *dst, const void *unsafe_src,
-		size_t size, bool strict)
+		size_t size)
 {
 	return true;
 }
 
 /**
- * probe_kernel_read(): safely attempt to read from any location
- * @dst: pointer to the buffer that shall take the data
- * @src: address to read from
- * @size: size of the data chunk
- *
- * Same as probe_kernel_read_strict() except that for architectures with
- * not fully separated user and kernel address spaces this function also works
- * for user address tanges.
- *
- * DO NOT USE THIS FUNCTION - it is broken on architectures with entirely
- * separate kernel and user address spaces, and also a bad idea otherwise.
- */
-long probe_kernel_read(void *dst, const void *src, size_t size)
-{
-	return __probe_kernel_read(dst, src, size, false);
-}
-EXPORT_SYMBOL_GPL(probe_kernel_read);
-
-/**
- * probe_kernel_read_strict(): safely attempt to read from kernel-space
+ * probe_kernel_read(): safely attempt to read from kernel-space
  * @dst: pointer to the buffer that shall take the data
  * @src: address to read from
  * @size: size of the data chunk
@@ -48,18 +26,12 @@ EXPORT_SYMBOL_GPL(probe_kernel_read);
  * probe_kernel_read() suitable for use within regions where the caller
  * already holds mmap_sem, or other locks which nest inside mmap_sem.
  */
-long probe_kernel_read_strict(void *dst, const void *src, size_t size)
-{
-	return __probe_kernel_read(dst, src, size, true);
-}
-
-static long __probe_kernel_read(void *dst, const void *src, size_t size,
-		bool strict)
+long probe_kernel_read(void *dst, const void *src, size_t size)
 {
 	long ret;
 	mm_segment_t old_fs = get_fs();
 
-	if (!probe_kernel_read_allowed(dst, src, size, strict))
+	if (!probe_kernel_read_allowed(dst, src, size))
 		return -EFAULT;
 
 	set_fs(KERNEL_DS);
@@ -73,6 +45,7 @@ static long __probe_kernel_read(void *dst, const void *src, size_t size,
 		return -EFAULT;
 	return 0;
 }
+EXPORT_SYMBOL_GPL(probe_kernel_read);
 
 /**
  * probe_user_read(): safely attempt to read from a user-space location
@@ -180,7 +153,7 @@ long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
 
 	if (unlikely(count <= 0))
 		return 0;
-	if (!probe_kernel_read_allowed(dst, unsafe_addr, count, true))
+	if (!probe_kernel_read_allowed(dst, unsafe_addr, count))
 		return -EFAULT;
 
 	set_fs(KERNEL_DS);
-- 
2.26.2


^ permalink raw reply	[flat|nested] 33+ messages in thread

* [PATCH 14/20] maccess: move user access routines together
  2020-05-19 13:44 clean up and streamline probe_kernel_* and friends v3 Christoph Hellwig
                   ` (12 preceding siblings ...)
  2020-05-19 13:44 ` [PATCH 13/20] maccess: always use strict semantics for probe_kernel_read Christoph Hellwig
@ 2020-05-19 13:44 ` Christoph Hellwig
  2020-05-19 13:44 ` [PATCH 15/20] maccess: allow architectures to provide kernel probing directly Christoph Hellwig
                   ` (6 subsequent siblings)
  20 siblings, 0 replies; 33+ messages in thread
From: Christoph Hellwig @ 2020-05-19 13:44 UTC (permalink / raw)
  To: x86, Alexei Starovoitov, Daniel Borkmann, Masami Hiramatsu,
	Linus Torvalds, Andrew Morton
  Cc: linux-parisc, linux-um, netdev, bpf, linux-mm, linux-kernel

Move kernel access vs user access routines together to ease upcoming
ifdefs.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/maccess.c | 110 +++++++++++++++++++++++++--------------------------
 1 file changed, 55 insertions(+), 55 deletions(-)

diff --git a/mm/maccess.c b/mm/maccess.c
index 05c44d490b4e3..9773e2253b495 100644
--- a/mm/maccess.c
+++ b/mm/maccess.c
@@ -47,34 +47,6 @@ long probe_kernel_read(void *dst, const void *src, size_t size)
 }
 EXPORT_SYMBOL_GPL(probe_kernel_read);
 
-/**
- * probe_user_read(): safely attempt to read from a user-space location
- * @dst: pointer to the buffer that shall take the data
- * @src: address to read from. This must be a user address.
- * @size: size of the data chunk
- *
- * Safely read from user address @src to the buffer at @dst. If a kernel fault
- * happens, handle that and return -EFAULT.
- */
-long probe_user_read(void *dst, const void __user *src, size_t size)
-{
-	long ret = -EFAULT;
-	mm_segment_t old_fs = get_fs();
-
-	set_fs(USER_DS);
-	if (access_ok(src, size)) {
-		pagefault_disable();
-		ret = __copy_from_user_inatomic(dst, src, size);
-		pagefault_enable();
-	}
-	set_fs(old_fs);
-
-	if (ret)
-		return -EFAULT;
-	return 0;
-}
-EXPORT_SYMBOL_GPL(probe_user_read);
-
 /**
  * probe_kernel_write(): safely attempt to write to a location
  * @dst: address to write to
@@ -100,33 +72,6 @@ long probe_kernel_write(void *dst, const void *src, size_t size)
 	return 0;
 }
 
-/**
- * probe_user_write(): safely attempt to write to a user-space location
- * @dst: address to write to
- * @src: pointer to the data that shall be written
- * @size: size of the data chunk
- *
- * Safely write to address @dst from the buffer at @src.  If a kernel fault
- * happens, handle that and return -EFAULT.
- */
-long probe_user_write(void __user *dst, const void *src, size_t size)
-{
-	long ret = -EFAULT;
-	mm_segment_t old_fs = get_fs();
-
-	set_fs(USER_DS);
-	if (access_ok(dst, size)) {
-		pagefault_disable();
-		ret = __copy_to_user_inatomic(dst, src, size);
-		pagefault_enable();
-	}
-	set_fs(old_fs);
-
-	if (ret)
-		return -EFAULT;
-	return 0;
-}
-
 /**
  * strncpy_from_kernel_nofault: - Copy a NUL terminated string from unsafe
  *				 address.
@@ -170,6 +115,61 @@ long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
 	return ret ? -EFAULT : src - unsafe_addr;
 }
 
+/**
+ * probe_user_read(): safely attempt to read from a user-space location
+ * @dst: pointer to the buffer that shall take the data
+ * @src: address to read from. This must be a user address.
+ * @size: size of the data chunk
+ *
+ * Safely read from user address @src to the buffer at @dst. If a kernel fault
+ * happens, handle that and return -EFAULT.
+ */
+long probe_user_read(void *dst, const void __user *src, size_t size)
+{
+	long ret = -EFAULT;
+	mm_segment_t old_fs = get_fs();
+
+	set_fs(USER_DS);
+	if (access_ok(src, size)) {
+		pagefault_disable();
+		ret = __copy_from_user_inatomic(dst, src, size);
+		pagefault_enable();
+	}
+	set_fs(old_fs);
+
+	if (ret)
+		return -EFAULT;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(probe_user_read);
+
+/**
+ * probe_user_write(): safely attempt to write to a user-space location
+ * @dst: address to write to
+ * @src: pointer to the data that shall be written
+ * @size: size of the data chunk
+ *
+ * Safely write to address @dst from the buffer at @src.  If a kernel fault
+ * happens, handle that and return -EFAULT.
+ */
+long probe_user_write(void __user *dst, const void *src, size_t size)
+{
+	long ret = -EFAULT;
+	mm_segment_t old_fs = get_fs();
+
+	set_fs(USER_DS);
+	if (access_ok(dst, size)) {
+		pagefault_disable();
+		ret = __copy_to_user_inatomic(dst, src, size);
+		pagefault_enable();
+	}
+	set_fs(old_fs);
+
+	if (ret)
+		return -EFAULT;
+	return 0;
+}
+
 /**
  * strncpy_from_user_nofault: - Copy a NUL terminated string from unsafe user
  *				address.
-- 
2.26.2


^ permalink raw reply	[flat|nested] 33+ messages in thread

* [PATCH 15/20] maccess: allow architectures to provide kernel probing directly
  2020-05-19 13:44 clean up and streamline probe_kernel_* and friends v3 Christoph Hellwig
                   ` (13 preceding siblings ...)
  2020-05-19 13:44 ` [PATCH 14/20] maccess: move user access routines together Christoph Hellwig
@ 2020-05-19 13:44 ` Christoph Hellwig
  2020-05-19 13:44 ` [PATCH 16/20] x86: use non-set_fs based maccess routines Christoph Hellwig
                   ` (5 subsequent siblings)
  20 siblings, 0 replies; 33+ messages in thread
From: Christoph Hellwig @ 2020-05-19 13:44 UTC (permalink / raw)
  To: x86, Alexei Starovoitov, Daniel Borkmann, Masami Hiramatsu,
	Linus Torvalds, Andrew Morton
  Cc: linux-parisc, linux-um, netdev, bpf, linux-mm, linux-kernel

Provide alternative versions of probe_kernel_read, probe_kernel_write
and strncpy_from_kernel_unsafe that don't need set_fs magic, but instead
use arch hooks that are modelled after unsafe_{get,put}_user to access
kernel memory in an exception safe way.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/maccess.c | 76 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 76 insertions(+)

diff --git a/mm/maccess.c b/mm/maccess.c
index 9773e2253b495..01129cbdf4484 100644
--- a/mm/maccess.c
+++ b/mm/maccess.c
@@ -12,6 +12,81 @@ bool __weak probe_kernel_read_allowed(void *dst, const void *unsafe_src,
 	return true;
 }
 
+#ifdef HAVE_GET_KERNEL_NOFAULT
+
+#define probe_kernel_read_loop(dst, src, len, type, err_label)		\
+	while (len >= sizeof(type)) {					\
+		__get_kernel_nofault(dst, src, type, err_label);		\
+		dst += sizeof(type);					\
+		src += sizeof(type);					\
+		len -= sizeof(type);					\
+	}
+
+long probe_kernel_read(void *dst, const void *src, size_t size)
+{
+	if (!probe_kernel_read_allowed(dst, src, size))
+		return -EFAULT;
+
+	pagefault_disable();
+	probe_kernel_read_loop(dst, src, size, u64, Efault);
+	probe_kernel_read_loop(dst, src, size, u32, Efault);
+	probe_kernel_read_loop(dst, src, size, u16, Efault);
+	probe_kernel_read_loop(dst, src, size, u8, Efault);
+	pagefault_enable();
+	return 0;
+Efault:
+	pagefault_enable();
+	return -EFAULT;
+}
+EXPORT_SYMBOL_GPL(probe_kernel_read);
+
+#define probe_kernel_write_loop(dst, src, len, type, err_label)		\
+	while (len >= sizeof(type)) {					\
+		__put_kernel_nofault(dst, src, type, err_label);		\
+		dst += sizeof(type);					\
+		src += sizeof(type);					\
+		len -= sizeof(type);					\
+	}
+
+long probe_kernel_write(void *dst, const void *src, size_t size)
+{
+	pagefault_disable();
+	probe_kernel_write_loop(dst, src, size, u64, Efault);
+	probe_kernel_write_loop(dst, src, size, u32, Efault);
+	probe_kernel_write_loop(dst, src, size, u16, Efault);
+	probe_kernel_write_loop(dst, src, size, u8, Efault);
+	pagefault_enable();
+	return 0;
+Efault:
+	pagefault_enable();
+	return -EFAULT;
+}
+
+long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
+{
+	const void *src = unsafe_addr;
+
+	if (unlikely(count <= 0))
+		return 0;
+	if (!probe_kernel_read_allowed(dst, unsafe_addr, count))
+		return -EFAULT;
+
+	pagefault_disable();
+	do {
+		__get_kernel_nofault(dst, src, u8, Efault);
+		dst++;
+		src++;
+	} while (dst[-1] && src - unsafe_addr < count);
+	pagefault_enable();
+
+	dst[-1] = '\0';
+	return src - unsafe_addr;
+Efault:
+	pagefault_enable();
+	dst[-1] = '\0';
+	return -EFAULT;
+}
+#else /* HAVE_GET_KERNEL_NOFAULT */
 /**
  * probe_kernel_read(): safely attempt to read from kernel-space
  * @dst: pointer to the buffer that shall take the data
@@ -114,6 +189,7 @@ long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
 
 	return ret ? -EFAULT : src - unsafe_addr;
 }
+#endif /* HAVE_GET_KERNEL_NOFAULT */
 
 /**
  * probe_user_read(): safely attempt to read from a user-space location
-- 
2.26.2


^ permalink raw reply	[flat|nested] 33+ messages in thread

* [PATCH 16/20] x86: use non-set_fs based maccess routines
  2020-05-19 13:44 clean up and streamline probe_kernel_* and friends v3 Christoph Hellwig
                   ` (14 preceding siblings ...)
  2020-05-19 13:44 ` [PATCH 15/20] maccess: allow architectures to provide kernel probing directly Christoph Hellwig
@ 2020-05-19 13:44 ` Christoph Hellwig
  2020-05-19 13:44 ` [PATCH 17/20] maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault Christoph Hellwig
                   ` (4 subsequent siblings)
  20 siblings, 0 replies; 33+ messages in thread
From: Christoph Hellwig @ 2020-05-19 13:44 UTC (permalink / raw)
  To: x86, Alexei Starovoitov, Daniel Borkmann, Masami Hiramatsu,
	Linus Torvalds, Andrew Morton
  Cc: linux-parisc, linux-um, netdev, bpf, linux-mm, linux-kernel

Provide arch_kernel_read and arch_kernel_write routines to implement the
maccess routines without messing with set_fs and without stac/clac that
opens up access to user space.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/x86/include/asm/uaccess.h | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index d8f283b9a569c..b3e0a56ae961a 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -523,5 +523,21 @@ do {									\
 	unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u8, label);	\
 } while (0)
 
+#define HAVE_GET_KERNEL_NOFAULT
+
+#define __get_kernel_nofault(dst, src, type, err_label)			\
+do {									\
+        int __kr_err;							\
+									\
+	__get_user_size(*((type *)dst), (__force type __user *)src,	\
+			sizeof(type), __kr_err);			\
+        if (unlikely(__kr_err))						\
+		goto err_label;						\
+} while (0)
+
+#define __put_kernel_nofault(dst, src, type, err_label)			\
+	__put_user_size(*((type *)(src)), (__force type __user *)(dst),	\
+			sizeof(type), err_label)
+
 #endif /* _ASM_X86_UACCESS_H */
 
-- 
2.26.2


^ permalink raw reply	[flat|nested] 33+ messages in thread

* [PATCH 17/20] maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault
  2020-05-19 13:44 clean up and streamline probe_kernel_* and friends v3 Christoph Hellwig
                   ` (15 preceding siblings ...)
  2020-05-19 13:44 ` [PATCH 16/20] x86: use non-set_fs based maccess routines Christoph Hellwig
@ 2020-05-19 13:44 ` Christoph Hellwig
  2020-05-19 13:44 ` [PATCH 18/20] maccess: rename probe_user_{read,write} to copy_{from,to}_user_nofault Christoph Hellwig
                   ` (3 subsequent siblings)
  20 siblings, 0 replies; 33+ messages in thread
From: Christoph Hellwig @ 2020-05-19 13:44 UTC (permalink / raw)
  To: x86, Alexei Starovoitov, Daniel Borkmann, Masami Hiramatsu,
	Linus Torvalds, Andrew Morton
  Cc: linux-parisc, linux-um, netdev, bpf, linux-mm, linux-kernel

Better describe what these functions do.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/arm/kernel/ftrace.c           |  3 +-
 arch/arm/kernel/kgdb.c             |  2 +-
 arch/arm64/kernel/insn.c           |  4 +--
 arch/csky/kernel/ftrace.c          |  5 ++--
 arch/ia64/kernel/ftrace.c          |  6 ++--
 arch/mips/kernel/kprobes.c         |  6 ++--
 arch/nds32/kernel/ftrace.c         |  5 ++--
 arch/parisc/kernel/ftrace.c        |  2 +-
 arch/parisc/kernel/kgdb.c          |  4 +--
 arch/parisc/lib/memcpy.c           |  3 +-
 arch/powerpc/kernel/module_64.c    |  5 ++--
 arch/powerpc/kernel/trace/ftrace.c | 24 +++++++--------
 arch/powerpc/perf/core-book3s.c    |  3 +-
 arch/riscv/kernel/ftrace.c         |  3 +-
 arch/riscv/kernel/patch.c          |  4 +--
 arch/s390/kernel/ftrace.c          |  4 +--
 arch/sh/kernel/ftrace.c            |  6 ++--
 arch/um/kernel/maccess.c           |  2 +-
 arch/x86/include/asm/ptrace.h      |  4 +--
 arch/x86/kernel/dumpstack.c        |  2 +-
 arch/x86/kernel/ftrace.c           |  8 ++---
 arch/x86/kernel/kgdb.c             |  6 ++--
 arch/x86/kernel/kprobes/core.c     |  5 ++--
 arch/x86/kernel/kprobes/opt.c      |  2 +-
 arch/x86/kernel/traps.c            |  3 +-
 arch/x86/mm/fault.c                |  2 +-
 arch/x86/mm/init_32.c              |  2 +-
 arch/x86/mm/maccess.c              |  3 +-
 arch/x86/xen/enlighten_pv.c        |  2 +-
 drivers/char/mem.c                 |  2 +-
 drivers/dio/dio.c                  |  6 ++--
 drivers/input/serio/hp_sdc.c       |  2 +-
 drivers/misc/kgdbts.c              |  6 ++--
 drivers/video/fbdev/hpfb.c         |  2 +-
 fs/proc/kcore.c                    |  3 +-
 include/linux/uaccess.h            | 14 +++++----
 kernel/debug/debug_core.c          |  6 ++--
 kernel/debug/gdbstub.c             |  6 ++--
 kernel/debug/kdb/kdb_main.c        |  3 +-
 kernel/debug/kdb/kdb_support.c     |  7 +++--
 kernel/kthread.c                   |  2 +-
 kernel/trace/bpf_trace.c           |  2 +-
 kernel/trace/trace_kprobe.c        |  4 +--
 kernel/workqueue.c                 | 10 +++----
 mm/maccess.c                       | 48 +++++++++++++++---------------
 mm/rodata_test.c                   |  2 +-
 mm/slub.c                          |  2 +-
 47 files changed, 137 insertions(+), 120 deletions(-)

diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
index 10499d44964a2..9a79ef6b1876c 100644
--- a/arch/arm/kernel/ftrace.c
+++ b/arch/arm/kernel/ftrace.c
@@ -84,7 +84,8 @@ static int ftrace_modify_code(unsigned long pc, unsigned long old,
 		old = __opcode_to_mem_arm(old);
 
 	if (validate) {
-		if (probe_kernel_read(&replaced, (void *)pc, MCOUNT_INSN_SIZE))
+		if (copy_from_kernel_nofault(&replaced, (void *)pc,
+				MCOUNT_INSN_SIZE))
 			return -EFAULT;
 
 		if (replaced != old)
diff --git a/arch/arm/kernel/kgdb.c b/arch/arm/kernel/kgdb.c
index 6a95b92966406..7bd30c0a4280d 100644
--- a/arch/arm/kernel/kgdb.c
+++ b/arch/arm/kernel/kgdb.c
@@ -236,7 +236,7 @@ int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
 	/* patch_text() only supports int-sized breakpoints */
 	BUILD_BUG_ON(sizeof(int) != BREAK_INSTR_SIZE);
 
-	err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr,
+	err = copy_from_kernel_nofault(bpt->saved_instr, (char *)bpt->bpt_addr,
 				BREAK_INSTR_SIZE);
 	if (err)
 		return err;
diff --git a/arch/arm64/kernel/insn.c b/arch/arm64/kernel/insn.c
index 4a9e773a177f0..c5f7a7b8d2c3e 100644
--- a/arch/arm64/kernel/insn.c
+++ b/arch/arm64/kernel/insn.c
@@ -123,7 +123,7 @@ int __kprobes aarch64_insn_read(void *addr, u32 *insnp)
 	int ret;
 	__le32 val;
 
-	ret = probe_kernel_read(&val, addr, AARCH64_INSN_SIZE);
+	ret = copy_from_kernel_nofault(&val, addr, AARCH64_INSN_SIZE);
 	if (!ret)
 		*insnp = le32_to_cpu(val);
 
@@ -139,7 +139,7 @@ static int __kprobes __aarch64_insn_write(void *addr, __le32 insn)
 	raw_spin_lock_irqsave(&patch_lock, flags);
 	waddr = patch_map(addr, FIX_TEXT_POKE0);
 
-	ret = probe_kernel_write(waddr, &insn, AARCH64_INSN_SIZE);
+	ret = copy_to_kernel_nofault(waddr, &insn, AARCH64_INSN_SIZE);
 
 	patch_unmap(FIX_TEXT_POKE0);
 	raw_spin_unlock_irqrestore(&patch_lock, flags);
diff --git a/arch/csky/kernel/ftrace.c b/arch/csky/kernel/ftrace.c
index 3c425b84e3be6..b4a7ec1517ff7 100644
--- a/arch/csky/kernel/ftrace.c
+++ b/arch/csky/kernel/ftrace.c
@@ -72,7 +72,8 @@ static int ftrace_check_current_nop(unsigned long hook)
 	uint16_t olds[7];
 	unsigned long hook_pos = hook - 2;
 
-	if (probe_kernel_read((void *)olds, (void *)hook_pos, sizeof(nops)))
+	if (copy_from_kernel_nofault((void *)olds, (void *)hook_pos,
+			sizeof(nops)))
 		return -EFAULT;
 
 	if (memcmp((void *)nops, (void *)olds, sizeof(nops))) {
@@ -97,7 +98,7 @@ static int ftrace_modify_code(unsigned long hook, unsigned long target,
 
 	make_jbsr(target, hook, call, nolr);
 
-	ret = probe_kernel_write((void *)hook_pos, enable ? call : nops,
+	ret = copy_to_kernel_nofault((void *)hook_pos, enable ? call : nops,
 				 sizeof(nops));
 	if (ret)
 		return -EPERM;
diff --git a/arch/ia64/kernel/ftrace.c b/arch/ia64/kernel/ftrace.c
index cee411e647ca0..b2ab2d58fb30c 100644
--- a/arch/ia64/kernel/ftrace.c
+++ b/arch/ia64/kernel/ftrace.c
@@ -108,7 +108,7 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code,
 		goto skip_check;
 
 	/* read the text we want to modify */
-	if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
+	if (copy_from_kernel_nofault(replaced, (void *)ip, MCOUNT_INSN_SIZE))
 		return -EFAULT;
 
 	/* Make sure it is what we expect it to be */
@@ -117,7 +117,7 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code,
 
 skip_check:
 	/* replace the text with the new text */
-	if (probe_kernel_write(((void *)ip), new_code, MCOUNT_INSN_SIZE))
+	if (copy_to_kernel_nofault(((void *)ip), new_code, MCOUNT_INSN_SIZE))
 		return -EPERM;
 	flush_icache_range(ip, ip + MCOUNT_INSN_SIZE);
 
@@ -129,7 +129,7 @@ static int ftrace_make_nop_check(struct dyn_ftrace *rec, unsigned long addr)
 	unsigned char __attribute__((aligned(8))) replaced[MCOUNT_INSN_SIZE];
 	unsigned long ip = rec->ip;
 
-	if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
+	if (copy_from_kernel_nofault(replaced, (void *)ip, MCOUNT_INSN_SIZE))
 		return -EFAULT;
 	if (rec->flags & FTRACE_FL_CONVERTED) {
 		struct ftrace_call_insn *call_insn, *tmp_call;
diff --git a/arch/mips/kernel/kprobes.c b/arch/mips/kernel/kprobes.c
index 6cfae2411c044..d043c2f897fc2 100644
--- a/arch/mips/kernel/kprobes.c
+++ b/arch/mips/kernel/kprobes.c
@@ -86,9 +86,9 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
 		goto out;
 	}
 
-	if ((probe_kernel_read(&prev_insn, p->addr - 1,
-				sizeof(mips_instruction)) == 0) &&
-				insn_has_delayslot(prev_insn)) {
+	if (copy_from_kernel_nofault(&prev_insn, p->addr - 1,
+			sizeof(mips_instruction)) == 0 &&
+	    insn_has_delayslot(prev_insn)) {
 		pr_notice("Kprobes for branch delayslot are not supported\n");
 		ret = -EINVAL;
 		goto out;
diff --git a/arch/nds32/kernel/ftrace.c b/arch/nds32/kernel/ftrace.c
index 22ab77ea27ad3..3763b3f8c3db5 100644
--- a/arch/nds32/kernel/ftrace.c
+++ b/arch/nds32/kernel/ftrace.c
@@ -131,13 +131,14 @@ static int __ftrace_modify_code(unsigned long pc, unsigned long *old_insn,
 	unsigned long orig_insn[3];
 
 	if (validate) {
-		if (probe_kernel_read(orig_insn, (void *)pc, MCOUNT_INSN_SIZE))
+		if (copy_from_kernel_nofault(orig_insn, (void *)pc,
+				MCOUNT_INSN_SIZE))
 			return -EFAULT;
 		if (memcmp(orig_insn, old_insn, MCOUNT_INSN_SIZE))
 			return -EINVAL;
 	}
 
-	if (probe_kernel_write((void *)pc, new_insn, MCOUNT_INSN_SIZE))
+	if (copy_to_kernel_nofault((void *)pc, new_insn, MCOUNT_INSN_SIZE))
 		return -EPERM;
 
 	return 0;
diff --git a/arch/parisc/kernel/ftrace.c b/arch/parisc/kernel/ftrace.c
index b836fc61a24f4..1df0f67ed6671 100644
--- a/arch/parisc/kernel/ftrace.c
+++ b/arch/parisc/kernel/ftrace.c
@@ -172,7 +172,7 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 
 	ip = (void *)(rec->ip + 4 - size);
 
-	ret = probe_kernel_read(insn, ip, size);
+	ret = copy_from_kernel_nofault(insn, ip, size);
 	if (ret)
 		return ret;
 
diff --git a/arch/parisc/kernel/kgdb.c b/arch/parisc/kernel/kgdb.c
index 664278db9b977..c4554ac13eac7 100644
--- a/arch/parisc/kernel/kgdb.c
+++ b/arch/parisc/kernel/kgdb.c
@@ -154,8 +154,8 @@ void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip)
 
 int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
 {
-	int ret = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr,
-				BREAK_INSTR_SIZE);
+	int ret = copy_from_kernel_nofault(bpt->saved_instr,
+			(char *)bpt->bpt_addr, BREAK_INSTR_SIZE);
 	if (ret)
 		return ret;
 
diff --git a/arch/parisc/lib/memcpy.c b/arch/parisc/lib/memcpy.c
index 9fe662b3b5604..f51811d613d72 100644
--- a/arch/parisc/lib/memcpy.c
+++ b/arch/parisc/lib/memcpy.c
@@ -57,7 +57,8 @@ void * memcpy(void * dst,const void *src, size_t count)
 EXPORT_SYMBOL(raw_copy_in_user);
 EXPORT_SYMBOL(memcpy);
 
-bool probe_kernel_read_allowed(void *dst, const void *unsafe_src, size_t size)
+bool copy_from_kernel_nofault_allowed(void *dst, const void *unsafe_src,
+		size_t size)
 {
 	if ((unsigned long)unsafe_src < PAGE_SIZE)
 		return false;
diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c
index 007606a48fd98..29067ef485411 100644
--- a/arch/powerpc/kernel/module_64.c
+++ b/arch/powerpc/kernel/module_64.c
@@ -159,7 +159,7 @@ int module_trampoline_target(struct module *mod, unsigned long addr,
 
 	stub = (struct ppc64_stub_entry *)addr;
 
-	if (probe_kernel_read(&magic, &stub->magic, sizeof(magic))) {
+	if (copy_from_kernel_nofault(&magic, &stub->magic, sizeof(magic))) {
 		pr_err("%s: fault reading magic for stub %lx for %s\n", __func__, addr, mod->name);
 		return -EFAULT;
 	}
@@ -169,7 +169,8 @@ int module_trampoline_target(struct module *mod, unsigned long addr,
 		return -EFAULT;
 	}
 
-	if (probe_kernel_read(&funcdata, &stub->funcdata, sizeof(funcdata))) {
+	if (copy_from_kernel_nofault(&funcdata, &stub->funcdata,
+			sizeof(funcdata))) {
 		pr_err("%s: fault reading funcdata for stub %lx for %s\n", __func__, addr, mod->name);
                 return -EFAULT;
 	}
diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c
index 7ea0ca044b650..60ee6813830c3 100644
--- a/arch/powerpc/kernel/trace/ftrace.c
+++ b/arch/powerpc/kernel/trace/ftrace.c
@@ -67,7 +67,7 @@ ftrace_modify_code(unsigned long ip, unsigned int old, unsigned int new)
 	 */
 
 	/* read the text we want to modify */
-	if (probe_kernel_read(&replaced, (void *)ip, MCOUNT_INSN_SIZE))
+	if (copy_from_kernel_nofault(&replaced, (void *)ip, MCOUNT_INSN_SIZE))
 		return -EFAULT;
 
 	/* Make sure it is what we expect it to be */
@@ -128,7 +128,7 @@ __ftrace_make_nop(struct module *mod,
 	unsigned int op, pop;
 
 	/* read where this goes */
-	if (probe_kernel_read(&op, (void *)ip, sizeof(int))) {
+	if (copy_from_kernel_nofault(&op, (void *)ip, sizeof(int))) {
 		pr_err("Fetching opcode failed.\n");
 		return -EFAULT;
 	}
@@ -162,7 +162,7 @@ __ftrace_make_nop(struct module *mod,
 	/* When using -mkernel_profile there is no load to jump over */
 	pop = PPC_INST_NOP;
 
-	if (probe_kernel_read(&op, (void *)(ip - 4), 4)) {
+	if (copy_from_kernel_nofault(&op, (void *)(ip - 4), 4)) {
 		pr_err("Fetching instruction at %lx failed.\n", ip - 4);
 		return -EFAULT;
 	}
@@ -193,7 +193,7 @@ __ftrace_make_nop(struct module *mod,
 	 * Check what is in the next instruction. We can see ld r2,40(r1), but
 	 * on first pass after boot we will see mflr r0.
 	 */
-	if (probe_kernel_read(&op, (void *)(ip+4), MCOUNT_INSN_SIZE)) {
+	if (copy_from_kernel_nofault(&op, (void *)(ip+4), MCOUNT_INSN_SIZE)) {
 		pr_err("Fetching op failed.\n");
 		return -EFAULT;
 	}
@@ -222,7 +222,7 @@ __ftrace_make_nop(struct module *mod,
 	unsigned long ip = rec->ip;
 	unsigned long tramp;
 
-	if (probe_kernel_read(&op, (void *)ip, MCOUNT_INSN_SIZE))
+	if (copy_from_kernel_nofault(&op, (void *)ip, MCOUNT_INSN_SIZE))
 		return -EFAULT;
 
 	/* Make sure that that this is still a 24bit jump */
@@ -245,7 +245,7 @@ __ftrace_make_nop(struct module *mod,
 	pr_devel("ip:%lx jumps to %lx", ip, tramp);
 
 	/* Find where the trampoline jumps to */
-	if (probe_kernel_read(jmp, (void *)tramp, sizeof(jmp))) {
+	if (copy_from_kernel_nofault(jmp, (void *)tramp, sizeof(jmp))) {
 		pr_err("Failed to read %lx\n", tramp);
 		return -EFAULT;
 	}
@@ -341,7 +341,7 @@ static int setup_mcount_compiler_tramp(unsigned long tramp)
 			return -1;
 
 	/* New trampoline -- read where this goes */
-	if (probe_kernel_read(&op, (void *)tramp, sizeof(int))) {
+	if (copy_from_kernel_nofault(&op, (void *)tramp, sizeof(int))) {
 		pr_debug("Fetching opcode failed.\n");
 		return -1;
 	}
@@ -391,7 +391,7 @@ static int __ftrace_make_nop_kernel(struct dyn_ftrace *rec, unsigned long addr)
 	unsigned int op;
 
 	/* Read where this goes */
-	if (probe_kernel_read(&op, (void *)ip, sizeof(int))) {
+	if (copy_from_kernel_nofault(&op, (void *)ip, sizeof(int))) {
 		pr_err("Fetching opcode failed.\n");
 		return -EFAULT;
 	}
@@ -516,7 +516,7 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 	struct module *mod = rec->arch.mod;
 
 	/* read where this goes */
-	if (probe_kernel_read(op, ip, sizeof(op)))
+	if (copy_from_kernel_nofault(op, ip, sizeof(op)))
 		return -EFAULT;
 
 	if (!expected_nop_sequence(ip, op[0], op[1])) {
@@ -578,7 +578,7 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 	unsigned long ip = rec->ip;
 
 	/* read where this goes */
-	if (probe_kernel_read(&op, (void *)ip, MCOUNT_INSN_SIZE))
+	if (copy_from_kernel_nofault(&op, (void *)ip, MCOUNT_INSN_SIZE))
 		return -EFAULT;
 
 	/* It should be pointing to a nop */
@@ -634,7 +634,7 @@ static int __ftrace_make_call_kernel(struct dyn_ftrace *rec, unsigned long addr)
 	}
 
 	/* Make sure we have a nop */
-	if (probe_kernel_read(&op, ip, sizeof(op))) {
+	if (copy_from_kernel_nofault(&op, ip, sizeof(op))) {
 		pr_err("Unable to read ftrace location %p\n", ip);
 		return -EFAULT;
 	}
@@ -712,7 +712,7 @@ __ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
 	}
 
 	/* read where this goes */
-	if (probe_kernel_read(&op, (void *)ip, sizeof(int))) {
+	if (copy_from_kernel_nofault(&op, (void *)ip, sizeof(int))) {
 		pr_err("Fetching opcode failed.\n");
 		return -EFAULT;
 	}
diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
index 3dcfecf858f36..50bc9f0eb6be3 100644
--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c
@@ -418,7 +418,8 @@ static __u64 power_pmu_bhrb_to(u64 addr)
 	__u64 target;
 
 	if (is_kernel_addr(addr)) {
-		if (probe_kernel_read(&instr, (void *)addr, sizeof(instr)))
+		if (copy_from_kernel_nofault(&instr, (void *)addr,
+				sizeof(instr)))
 			return 0;
 
 		return branch_target(&instr);
diff --git a/arch/riscv/kernel/ftrace.c b/arch/riscv/kernel/ftrace.c
index ce69b34ff55d0..143a22ab8853e 100644
--- a/arch/riscv/kernel/ftrace.c
+++ b/arch/riscv/kernel/ftrace.c
@@ -25,7 +25,8 @@ static int ftrace_check_current_call(unsigned long hook_pos,
 	 * Read the text we want to modify;
 	 * return must be -EFAULT on read error
 	 */
-	if (probe_kernel_read(replaced, (void *)hook_pos, MCOUNT_INSN_SIZE))
+	if (copy_from_kernel_nofault(replaced, (void *)hook_pos,
+			MCOUNT_INSN_SIZE))
 		return -EFAULT;
 
 	/*
diff --git a/arch/riscv/kernel/patch.c b/arch/riscv/kernel/patch.c
index 8a4fc65ee0222..9a0ade9fa10b0 100644
--- a/arch/riscv/kernel/patch.c
+++ b/arch/riscv/kernel/patch.c
@@ -57,7 +57,7 @@ static int __kprobes riscv_insn_write(void *addr, const void *insn, size_t len)
 
 	waddr = patch_map(addr, FIX_TEXT_POKE0);
 
-	ret = probe_kernel_write(waddr, insn, len);
+	ret = copy_to_kernel_nofault(waddr, insn, len);
 
 	patch_unmap(FIX_TEXT_POKE0);
 
@@ -71,7 +71,7 @@ static int __kprobes riscv_insn_write(void *addr, const void *insn, size_t len)
 #else
 static int __kprobes riscv_insn_write(void *addr, const void *insn, size_t len)
 {
-	return probe_kernel_write(addr, insn, len);
+	return copy_to_kernel_nofault(addr, insn, len);
 }
 #endif /* CONFIG_MMU */
 
diff --git a/arch/s390/kernel/ftrace.c b/arch/s390/kernel/ftrace.c
index 4cd9b1ada8340..1576f0eede771 100644
--- a/arch/s390/kernel/ftrace.c
+++ b/arch/s390/kernel/ftrace.c
@@ -99,7 +99,7 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
 {
 	struct ftrace_insn orig, new, old;
 
-	if (probe_kernel_read(&old, (void *) rec->ip, sizeof(old)))
+	if (copy_from_kernel_nofault(&old, (void *) rec->ip, sizeof(old)))
 		return -EFAULT;
 	if (addr == MCOUNT_ADDR) {
 		/* Initial code replacement */
@@ -121,7 +121,7 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 {
 	struct ftrace_insn orig, new, old;
 
-	if (probe_kernel_read(&old, (void *) rec->ip, sizeof(old)))
+	if (copy_from_kernel_nofault(&old, (void *) rec->ip, sizeof(old)))
 		return -EFAULT;
 	/* Replace nop with an ftrace call. */
 	ftrace_generate_nop_insn(&orig);
diff --git a/arch/sh/kernel/ftrace.c b/arch/sh/kernel/ftrace.c
index 1b04270e5460e..0646c59618466 100644
--- a/arch/sh/kernel/ftrace.c
+++ b/arch/sh/kernel/ftrace.c
@@ -119,7 +119,7 @@ static void ftrace_mod_code(void)
 	 * But if one were to fail, then they all should, and if one were
 	 * to succeed, then they all should.
 	 */
-	mod_code_status = probe_kernel_write(mod_code_ip, mod_code_newcode,
+	mod_code_status = copy_to_kernel_nofault(mod_code_ip, mod_code_newcode,
 					     MCOUNT_INSN_SIZE);
 
 	/* if we fail, then kill any new writers */
@@ -203,7 +203,7 @@ static int ftrace_modify_code(unsigned long ip, unsigned char *old_code,
 	 */
 
 	/* read the text we want to modify */
-	if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
+	if (copy_from_kernel_nofault(replaced, (void *)ip, MCOUNT_INSN_SIZE))
 		return -EFAULT;
 
 	/* Make sure it is what we expect it to be */
@@ -268,7 +268,7 @@ static int ftrace_mod(unsigned long ip, unsigned long old_addr,
 {
 	unsigned char code[MCOUNT_INSN_SIZE];
 
-	if (probe_kernel_read(code, (void *)ip, MCOUNT_INSN_SIZE))
+	if (copy_from_kernel_nofault(code, (void *)ip, MCOUNT_INSN_SIZE))
 		return -EFAULT;
 
 	if (old_addr != __raw_readl((unsigned long *)code))
diff --git a/arch/um/kernel/maccess.c b/arch/um/kernel/maccess.c
index 734f3d7e57c0f..cedf73e9e8ce2 100644
--- a/arch/um/kernel/maccess.c
+++ b/arch/um/kernel/maccess.c
@@ -7,7 +7,7 @@
 #include <linux/kernel.h>
 #include <os.h>
 
-bool probe_kernel_read_allowed(void *dst, const void *src, size_t size)
+bool copy_from_kernel_nofault_allowed(void *dst, const void *src, size_t size)
 {
 	void *psrc = (void *)rounddown((unsigned long)src, PAGE_SIZE);
 
diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h
index 6d6475fdd3278..62ac40751276f 100644
--- a/arch/x86/include/asm/ptrace.h
+++ b/arch/x86/include/asm/ptrace.h
@@ -278,7 +278,7 @@ static inline unsigned long *regs_get_kernel_stack_nth_addr(struct pt_regs *regs
 }
 
 /* To avoid include hell, we can't include uaccess.h */
-extern long probe_kernel_read(void *dst, const void *src, size_t size);
+extern long copy_from_kernel_nofault(void *dst, const void *src, size_t size);
 
 /**
  * regs_get_kernel_stack_nth() - get Nth entry of the stack
@@ -298,7 +298,7 @@ static inline unsigned long regs_get_kernel_stack_nth(struct pt_regs *regs,
 
 	addr = regs_get_kernel_stack_nth_addr(regs, n);
 	if (addr) {
-		ret = probe_kernel_read(&val, addr, sizeof(val));
+		ret = copy_from_kernel_nofault(&val, addr, sizeof(val));
 		if (!ret)
 			return val;
 	}
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
index ae64ec7f752f4..f8dd06ccd8d2e 100644
--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -106,7 +106,7 @@ void show_opcodes(struct pt_regs *regs, const char *loglvl)
 	bad_ip = user_mode(regs) &&
 		__chk_range_not_ok(prologue, OPCODE_BUFSIZE, TASK_SIZE_MAX);
 
-	if (bad_ip || probe_kernel_read(opcodes, (u8 *)prologue,
+	if (bad_ip || copy_from_kernel_nofault(opcodes, (u8 *)prologue,
 					OPCODE_BUFSIZE)) {
 		printk("%sCode: Bad RIP value.\n", loglvl);
 	} else {
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index b0e641793be4f..3a27647d00560 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -86,7 +86,7 @@ static int ftrace_verify_code(unsigned long ip, const char *old_code)
 	 * sure what we read is what we expected it to be before modifying it.
 	 */
 	/* read the text we want to modify */
-	if (probe_kernel_read(cur_code, (void *)ip, MCOUNT_INSN_SIZE)) {
+	if (copy_from_kernel_nofault(cur_code, (void *)ip, MCOUNT_INSN_SIZE)) {
 		WARN_ON(1);
 		return -EFAULT;
 	}
@@ -354,7 +354,7 @@ create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
 	npages = DIV_ROUND_UP(*tramp_size, PAGE_SIZE);
 
 	/* Copy ftrace_caller onto the trampoline memory */
-	ret = probe_kernel_read(trampoline, (void *)start_offset, size);
+	ret = copy_from_kernel_nofault(trampoline, (void *)start_offset, size);
 	if (WARN_ON(ret < 0))
 		goto fail;
 
@@ -362,7 +362,7 @@ create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
 
 	/* The trampoline ends with ret(q) */
 	retq = (unsigned long)ftrace_stub;
-	ret = probe_kernel_read(ip, (void *)retq, RET_SIZE);
+	ret = copy_from_kernel_nofault(ip, (void *)retq, RET_SIZE);
 	if (WARN_ON(ret < 0))
 		goto fail;
 
@@ -498,7 +498,7 @@ static void *addr_from_call(void *ptr)
 	union text_poke_insn call;
 	int ret;
 
-	ret = probe_kernel_read(&call, ptr, CALL_INSN_SIZE);
+	ret = copy_from_kernel_nofault(&call, ptr, CALL_INSN_SIZE);
 	if (WARN_ON_ONCE(ret < 0))
 		return NULL;
 
diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index c44fe7d8d9a4e..68acd30c6b878 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -732,11 +732,11 @@ int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
 	int err;
 
 	bpt->type = BP_BREAKPOINT;
-	err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr,
+	err = copy_from_kernel_nofault(bpt->saved_instr, (char *)bpt->bpt_addr,
 				BREAK_INSTR_SIZE);
 	if (err)
 		return err;
-	err = probe_kernel_write((char *)bpt->bpt_addr,
+	err = copy_to_kernel_nofault((char *)bpt->bpt_addr,
 				 arch_kgdb_ops.gdb_bpt_instr, BREAK_INSTR_SIZE);
 	if (!err)
 		return err;
@@ -768,7 +768,7 @@ int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
 	return 0;
 
 knl_write:
-	return probe_kernel_write((char *)bpt->bpt_addr,
+	return copy_to_kernel_nofault((char *)bpt->bpt_addr,
 				  (char *)bpt->saved_instr, BREAK_INSTR_SIZE);
 }
 
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 4d7022a740ab0..ecffda528f86f 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -243,7 +243,7 @@ __recover_probed_insn(kprobe_opcode_t *buf, unsigned long addr)
 	 * Fortunately, we know that the original code is the ideal 5-byte
 	 * long NOP.
 	 */
-	if (probe_kernel_read(buf, (void *)addr,
+	if (copy_from_kernel_nofault(buf, (void *)addr,
 		MAX_INSN_SIZE * sizeof(kprobe_opcode_t)))
 		return 0UL;
 
@@ -346,7 +346,8 @@ int __copy_instruction(u8 *dest, u8 *src, u8 *real, struct insn *insn)
 		return 0;
 
 	/* This can access kernel text if given address is not recovered */
-	if (probe_kernel_read(dest, (void *)recovered_insn, MAX_INSN_SIZE))
+	if (copy_from_kernel_nofault(dest, (void *)recovered_insn,
+			MAX_INSN_SIZE))
 		return 0;
 
 	kernel_insn_init(insn, dest, MAX_INSN_SIZE);
diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c
index ea13f68882849..85696911093f4 100644
--- a/arch/x86/kernel/kprobes/opt.c
+++ b/arch/x86/kernel/kprobes/opt.c
@@ -56,7 +56,7 @@ unsigned long __recover_optprobed_insn(kprobe_opcode_t *buf, unsigned long addr)
 	 * overwritten by jump destination address. In this case, original
 	 * bytes must be recovered from op->optinsn.copied_insn buffer.
 	 */
-	if (probe_kernel_read(buf, (void *)addr,
+	if (copy_from_kernel_nofault(buf, (void *)addr,
 		MAX_INSN_SIZE * sizeof(kprobe_opcode_t)))
 		return 0UL;
 
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index d54cffdc7cac2..96809f6aad67d 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -483,7 +483,8 @@ static enum kernel_gp_hint get_kernel_gp_address(struct pt_regs *regs,
 	u8 insn_buf[MAX_INSN_SIZE];
 	struct insn insn;
 
-	if (probe_kernel_read(insn_buf, (void *)regs->ip, MAX_INSN_SIZE))
+	if (copy_from_kernel_nofault(insn_buf, (void *)regs->ip,
+			MAX_INSN_SIZE))
 		return GP_NO_HINT;
 
 	kernel_insn_init(&insn, insn_buf, MAX_INSN_SIZE);
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index a51df516b87bf..994e207abdf64 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -590,7 +590,7 @@ static void show_ldttss(const struct desc_ptr *gdt, const char *name, u16 index)
 		return;
 	}
 
-	if (probe_kernel_read(&desc, (void *)(gdt->address + offset),
+	if (copy_from_kernel_nofault(&desc, (void *)(gdt->address + offset),
 			      sizeof(struct ldttss_desc))) {
 		pr_alert("%s: 0x%hx -- GDT entry is not readable\n",
 			 name, index);
diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index 4222a010057a9..4253c95968932 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -758,7 +758,7 @@ static void __init test_wp_bit(void)
 
 	__set_fixmap(FIX_WP_TEST, __pa_symbol(empty_zero_page), PAGE_KERNEL_RO);
 
-	if (probe_kernel_write((char *)fix_to_virt(FIX_WP_TEST), &z, 1)) {
+	if (copy_to_kernel_nofault((char *)fix_to_virt(FIX_WP_TEST), &z, 1)) {
 		clear_fixmap(FIX_WP_TEST);
 		printk(KERN_CONT "Ok.\n");
 		return;
diff --git a/arch/x86/mm/maccess.c b/arch/x86/mm/maccess.c
index a1bd81677aa72..a29111d25a990 100644
--- a/arch/x86/mm/maccess.c
+++ b/arch/x86/mm/maccess.c
@@ -26,7 +26,8 @@ static __always_inline bool invalid_probe_range(u64 vaddr)
 }
 #endif
 
-bool probe_kernel_read_allowed(void *dst, const void *unsafe_src, size_t size)
+bool copy_from_kernel_nofault_allowed(void *dst, const void *unsafe_src,
+		size_t size)
 {
 	return !invalid_probe_range((unsigned long)unsafe_src);
 }
diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index 507f4fb88fa7f..0a76fd298d896 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -387,7 +387,7 @@ static void set_aliased_prot(void *v, pgprot_t prot)
 
 	preempt_disable();
 
-	probe_kernel_read(&dummy, v, 1);
+	copy_from_kernel_nofault(&dummy, v, 1);
 
 	if (HYPERVISOR_update_va_mapping((unsigned long)v, pte, 0))
 		BUG();
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 43dd0891ca1ed..12774655aff45 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -167,7 +167,7 @@ static ssize_t read_mem(struct file *file, char __user *buf,
 			if (!ptr)
 				goto failed;
 
-			probe = probe_kernel_read(bounce, ptr, sz);
+			probe = copy_from_kernel_nofault(bounce, ptr, sz);
 			unxlate_dev_mem_ptr(p, ptr);
 			if (probe)
 				goto failed;
diff --git a/drivers/dio/dio.c b/drivers/dio/dio.c
index c9aa15fb86a9a..193b40e7aec03 100644
--- a/drivers/dio/dio.c
+++ b/drivers/dio/dio.c
@@ -135,7 +135,8 @@ int __init dio_find(int deviceid)
 		else
 			va = ioremap(pa, PAGE_SIZE);
 
-                if (probe_kernel_read(&i, (unsigned char *)va + DIO_IDOFF, 1)) {
+		if (copy_from_kernel_nofault(&i,
+				(unsigned char *)va + DIO_IDOFF, 1)) {
 			if (scode >= DIOII_SCBASE)
 				iounmap(va);
                         continue;             /* no board present at that select code */
@@ -208,7 +209,8 @@ static int __init dio_init(void)
 		else
 			va = ioremap(pa, PAGE_SIZE);
 
-                if (probe_kernel_read(&i, (unsigned char *)va + DIO_IDOFF, 1)) {
+		if (copy_from_kernel_nofault(&i,
+				(unsigned char *)va + DIO_IDOFF, 1)) {
 			if (scode >= DIOII_SCBASE)
 				iounmap(va);
                         continue;              /* no board present at that select code */
diff --git a/drivers/input/serio/hp_sdc.c b/drivers/input/serio/hp_sdc.c
index 654252361653d..13eacf6ab4310 100644
--- a/drivers/input/serio/hp_sdc.c
+++ b/drivers/input/serio/hp_sdc.c
@@ -1021,7 +1021,7 @@ static int __init hp_sdc_register(void)
 	hp_sdc.base_io	 = (unsigned long) 0xf0428000;
 	hp_sdc.data_io	 = (unsigned long) hp_sdc.base_io + 1;
 	hp_sdc.status_io = (unsigned long) hp_sdc.base_io + 3;
-	if (!probe_kernel_read(&i, (unsigned char *)hp_sdc.data_io, 1))
+	if (!copy_from_kernel_nofault(&i, (unsigned char *)hp_sdc.data_io, 1))
 		hp_sdc.dev = (void *)1;
 	hp_sdc.dev_err   = hp_sdc_init();
 #endif
diff --git a/drivers/misc/kgdbts.c b/drivers/misc/kgdbts.c
index bccd341e9ae16..d5d2af4d10e66 100644
--- a/drivers/misc/kgdbts.c
+++ b/drivers/misc/kgdbts.c
@@ -828,7 +828,7 @@ static void run_plant_and_detach_test(int is_early)
 	char before[BREAK_INSTR_SIZE];
 	char after[BREAK_INSTR_SIZE];
 
-	probe_kernel_read(before, (char *)kgdbts_break_test,
+	copy_from_kernel_nofault(before, (char *)kgdbts_break_test,
 	  BREAK_INSTR_SIZE);
 	init_simple_test();
 	ts.tst = plant_and_detach_test;
@@ -836,8 +836,8 @@ static void run_plant_and_detach_test(int is_early)
 	/* Activate test with initial breakpoint */
 	if (!is_early)
 		kgdb_breakpoint();
-	probe_kernel_read(after, (char *)kgdbts_break_test,
-	  BREAK_INSTR_SIZE);
+	copy_from_kernel_nofault(after, (char *)kgdbts_break_test,
+			BREAK_INSTR_SIZE);
 	if (memcmp(before, after, BREAK_INSTR_SIZE)) {
 		printk(KERN_CRIT "kgdbts: ERROR kgdb corrupted memory\n");
 		panic("kgdb memory corruption");
diff --git a/drivers/video/fbdev/hpfb.c b/drivers/video/fbdev/hpfb.c
index f02be0db335e9..8d418abdd7678 100644
--- a/drivers/video/fbdev/hpfb.c
+++ b/drivers/video/fbdev/hpfb.c
@@ -402,7 +402,7 @@ int __init hpfb_init(void)
 	if (err)
 		return err;
 
-	err = probe_kernel_read(&i, (unsigned char *)INTFBVADDR + DIO_IDOFF, 1);
+	err = copy_from_kernel_nofault(&i, (unsigned char *)INTFBVADDR + DIO_IDOFF, 1);
 
 	if (!err && (i == DIO_ID_FBUFFER) && topcat_sid_ok(sid = DIO_SECID(INTFBVADDR))) {
 		if (!request_mem_region(INTFBPADDR, DIO_DEVSIZE, "Internal Topcat"))
diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
index 8ba492d44e689..e502414b35564 100644
--- a/fs/proc/kcore.c
+++ b/fs/proc/kcore.c
@@ -512,7 +512,8 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
 				 * Using bounce buffer to bypass the
 				 * hardened user copy kernel text checks.
 				 */
-				if (probe_kernel_read(buf, (void *) start, tsz)) {
+				if (copy_from_kernel_nofault(buf, (void *)start,
+						tsz)) {
 					if (clear_user(buffer, tsz)) {
 						ret = -EFAULT;
 						goto out;
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index 78e0ff8641559..849bc3dca54d6 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -301,13 +301,15 @@ copy_struct_from_user(void *dst, size_t ksize, const void __user *src,
 	return 0;
 }
 
-bool probe_kernel_read_allowed(void *dst, const void *unsafe_src, size_t size);
+bool copy_from_kernel_nofault_allowed(void *dst, const void *unsafe_src,
+		size_t size);
 
-extern long probe_kernel_read(void *dst, const void *src, size_t size);
-extern long probe_user_read(void *dst, const void __user *src, size_t size);
+long copy_from_kernel_nofault(void *dst, const void *src, size_t size);
+long notrace copy_to_kernel_nofault(void *dst, const void *src, size_t size);
 
-extern long notrace probe_kernel_write(void *dst, const void *src, size_t size);
-extern long notrace probe_user_write(void __user *dst, const void *src, size_t size);
+extern long probe_user_read(void *dst, const void __user *src, size_t size);
+extern long notrace probe_user_write(void __user *dst, const void *src,
+		size_t size);
 
 long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr,
 		long count);
@@ -324,7 +326,7 @@ long strnlen_user_nofault(const void __user *unsafe_addr, long count);
  * Returns 0 on success, or -EFAULT.
  */
 #define probe_kernel_address(addr, retval)		\
-	probe_kernel_read(&retval, addr, sizeof(retval))
+	copy_from_kernel_nofault(&retval, addr, sizeof(retval))
 
 #ifndef user_access_begin
 #define user_access_begin(ptr,len) access_ok(ptr, len)
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index 2b7c9b67931d6..b5c2492e0b010 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -171,18 +171,18 @@ int __weak kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
 {
 	int err;
 
-	err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr,
+	err = copy_from_kernel_nofault(bpt->saved_instr, (char *)bpt->bpt_addr,
 				BREAK_INSTR_SIZE);
 	if (err)
 		return err;
-	err = probe_kernel_write((char *)bpt->bpt_addr,
+	err = copy_to_kernel_nofault((char *)bpt->bpt_addr,
 				 arch_kgdb_ops.gdb_bpt_instr, BREAK_INSTR_SIZE);
 	return err;
 }
 
 int __weak kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
 {
-	return probe_kernel_write((char *)bpt->bpt_addr,
+	return copy_to_kernel_nofault((char *)bpt->bpt_addr,
 				  (char *)bpt->saved_instr, BREAK_INSTR_SIZE);
 }
 
diff --git a/kernel/debug/gdbstub.c b/kernel/debug/gdbstub.c
index 4b280fc7dd675..61774aec46b4c 100644
--- a/kernel/debug/gdbstub.c
+++ b/kernel/debug/gdbstub.c
@@ -247,7 +247,7 @@ char *kgdb_mem2hex(char *mem, char *buf, int count)
 	 */
 	tmp = buf + count;
 
-	err = probe_kernel_read(tmp, mem, count);
+	err = copy_from_kernel_nofault(tmp, mem, count);
 	if (err)
 		return NULL;
 	while (count > 0) {
@@ -283,7 +283,7 @@ int kgdb_hex2mem(char *buf, char *mem, int count)
 		*tmp_raw |= hex_to_bin(*tmp_hex--) << 4;
 	}
 
-	return probe_kernel_write(mem, tmp_raw, count);
+	return copy_to_kernel_nofault(mem, tmp_raw, count);
 }
 
 /*
@@ -335,7 +335,7 @@ static int kgdb_ebin2mem(char *buf, char *mem, int count)
 		size++;
 	}
 
-	return probe_kernel_write(mem, c, size);
+	return copy_to_kernel_nofault(mem, c, size);
 }
 
 #if DBG_MAX_REG_NUM > 0
diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index 515379cbf2092..31858c3839ca5 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -2325,7 +2325,8 @@ void kdb_ps1(const struct task_struct *p)
 	int cpu;
 	unsigned long tmp;
 
-	if (!p || probe_kernel_read(&tmp, (char *)p, sizeof(unsigned long)))
+	if (!p ||
+	    copy_from_kernel_nofault(&tmp, (char *)p, sizeof(unsigned long)))
 		return;
 
 	cpu = kdb_process_cpu(p);
diff --git a/kernel/debug/kdb/kdb_support.c b/kernel/debug/kdb/kdb_support.c
index b8e6306e7e133..004c5b6c87f89 100644
--- a/kernel/debug/kdb/kdb_support.c
+++ b/kernel/debug/kdb/kdb_support.c
@@ -325,7 +325,7 @@ char *kdb_strdup(const char *str, gfp_t type)
  */
 int kdb_getarea_size(void *res, unsigned long addr, size_t size)
 {
-	int ret = probe_kernel_read((char *)res, (char *)addr, size);
+	int ret = copy_from_kernel_nofault((char *)res, (char *)addr, size);
 	if (ret) {
 		if (!KDB_STATE(SUPPRESS)) {
 			kdb_printf("kdb_getarea: Bad address 0x%lx\n", addr);
@@ -350,7 +350,7 @@ int kdb_getarea_size(void *res, unsigned long addr, size_t size)
  */
 int kdb_putarea_size(unsigned long addr, void *res, size_t size)
 {
-	int ret = probe_kernel_read((char *)addr, (char *)res, size);
+	int ret = copy_from_kernel_nofault((char *)addr, (char *)res, size);
 	if (ret) {
 		if (!KDB_STATE(SUPPRESS)) {
 			kdb_printf("kdb_putarea: Bad address 0x%lx\n", addr);
@@ -624,7 +624,8 @@ char kdb_task_state_char (const struct task_struct *p)
 	char state;
 	unsigned long tmp;
 
-	if (!p || probe_kernel_read(&tmp, (char *)p, sizeof(unsigned long)))
+	if (!p ||
+	    copy_from_kernel_nofault(&tmp, (char *)p, sizeof(unsigned long)))
 		return 'E';
 
 	cpu = kdb_process_cpu(p);
diff --git a/kernel/kthread.c b/kernel/kthread.c
index bfbfa481be3a5..e19ebe61232ca 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -179,7 +179,7 @@ void *kthread_probe_data(struct task_struct *task)
 	struct kthread *kthread = to_kthread(task);
 	void *data = NULL;
 
-	probe_kernel_read(&data, &kthread->data, sizeof(data));
+	copy_from_kernel_nofault(&data, &kthread->data, sizeof(data));
 	return data;
 }
 
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index c6007d9a987d5..5b591d3b62af0 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -190,7 +190,7 @@ bpf_probe_read_kernel_common(void *dst, u32 size, const void *unsafe_ptr,
 	    compat && (unsigned long)unsafe_ptr < TASK_SIZE)
 		ret = probe_user_read(dst, user_ptr, size);
 	else
-		ret = probe_kernel_read(dst, unsafe_ptr, size);
+		ret = copy_from_kernel_nofault(dst, unsafe_ptr, size);
 	if (unlikely(ret < 0))
 		goto fail;
 
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 82da20e712507..dab7c22d3e131 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1213,7 +1213,7 @@ fetch_store_strlen(unsigned long addr)
 			ret = probe_user_read(&c,
 				(__force u8 __user *)addr + len, 1);
 		} else {
-			ret = probe_kernel_read(&c, (u8 *)addr + len, 1);
+			ret = copy_from_kernel_nofault(&c, (u8 *)addr + len, 1);
 		}
 		len++;
 	} while (c && ret == 0 && len < MAX_STRING_SIZE);
@@ -1296,7 +1296,7 @@ probe_mem_read(void *dest, void *src, size_t size)
 				size);
 	}
 
-	return probe_kernel_read(dest, src, size);
+	return copy_from_kernel_nofault(dest, src, size);
 }
 
 static nokprobe_inline int
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 891ccad5f2716..a1345ffa3a0ba 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -4627,11 +4627,11 @@ void print_worker_info(const char *log_lvl, struct task_struct *task)
 	 * Carefully copy the associated workqueue's workfn, name and desc.
 	 * Keep the original last '\0' in case the original is garbage.
 	 */
-	probe_kernel_read(&fn, &worker->current_func, sizeof(fn));
-	probe_kernel_read(&pwq, &worker->current_pwq, sizeof(pwq));
-	probe_kernel_read(&wq, &pwq->wq, sizeof(wq));
-	probe_kernel_read(name, wq->name, sizeof(name) - 1);
-	probe_kernel_read(desc, worker->desc, sizeof(desc) - 1);
+	copy_from_kernel_nofault(&fn, &worker->current_func, sizeof(fn));
+	copy_from_kernel_nofault(&pwq, &worker->current_pwq, sizeof(pwq));
+	copy_from_kernel_nofault(&wq, &pwq->wq, sizeof(wq));
+	copy_from_kernel_nofault(name, wq->name, sizeof(name) - 1);
+	copy_from_kernel_nofault(desc, worker->desc, sizeof(desc) - 1);
 
 	if (fn || name[0] || desc[0]) {
 		printk("%sWorkqueue: %s %ps", log_lvl, name, fn);
diff --git a/mm/maccess.c b/mm/maccess.c
index 01129cbdf4484..955b6c973f742 100644
--- a/mm/maccess.c
+++ b/mm/maccess.c
@@ -6,7 +6,7 @@
 #include <linux/mm.h>
 #include <linux/uaccess.h>
 
-bool __weak probe_kernel_read_allowed(void *dst, const void *unsafe_src,
+bool __weak copy_from_kernel_nofault_allowed(void *dst, const void *unsafe_src,
 		size_t size)
 {
 	return true;
@@ -14,7 +14,7 @@ bool __weak probe_kernel_read_allowed(void *dst, const void *unsafe_src,
 
 #ifdef HAVE_GET_KERNEL_NOFAULT
 
-#define probe_kernel_read_loop(dst, src, len, type, err_label)		\
+#define copy_from_kernel_nofault_loop(dst, src, len, type, err_label)	\
 	while (len >= sizeof(type)) {					\
 		__get_kernel_nofault(dst, src, type, err_label);		\
 		dst += sizeof(type);					\
@@ -22,25 +22,25 @@ bool __weak probe_kernel_read_allowed(void *dst, const void *unsafe_src,
 		len -= sizeof(type);					\
 	}
 
-long probe_kernel_read(void *dst, const void *src, size_t size)
+long copy_from_kernel_nofault(void *dst, const void *src, size_t size)
 {
-	if (!probe_kernel_read_allowed(dst, src, size))
+	if (!copy_from_kernel_nofault_allowed(dst, src, size))
 		return -EFAULT;
 
 	pagefault_disable();
-	probe_kernel_read_loop(dst, src, size, u64, Efault);
-	probe_kernel_read_loop(dst, src, size, u32, Efault);
-	probe_kernel_read_loop(dst, src, size, u16, Efault);
-	probe_kernel_read_loop(dst, src, size, u8, Efault);
+	copy_from_kernel_nofault_loop(dst, src, size, u64, Efault);
+	copy_from_kernel_nofault_loop(dst, src, size, u32, Efault);
+	copy_from_kernel_nofault_loop(dst, src, size, u16, Efault);
+	copy_from_kernel_nofault_loop(dst, src, size, u8, Efault);
 	pagefault_enable();
 	return 0;
 Efault:
 	pagefault_enable();
 	return -EFAULT;
 }
-EXPORT_SYMBOL_GPL(probe_kernel_read);
+EXPORT_SYMBOL_GPL(copy_from_kernel_nofault);
 
-#define probe_kernel_write_loop(dst, src, len, type, err_label)		\
+#define copy_to_kernel_nofault_loop(dst, src, len, type, err_label)	\
 	while (len >= sizeof(type)) {					\
 		__put_kernel_nofault(dst, src, type, err_label);		\
 		dst += sizeof(type);					\
@@ -48,13 +48,13 @@ EXPORT_SYMBOL_GPL(probe_kernel_read);
 		len -= sizeof(type);					\
 	}
 
-long probe_kernel_write(void *dst, const void *src, size_t size)
+long copy_to_kernel_nofault(void *dst, const void *src, size_t size)
 {
 	pagefault_disable();
-	probe_kernel_write_loop(dst, src, size, u64, Efault);
-	probe_kernel_write_loop(dst, src, size, u32, Efault);
-	probe_kernel_write_loop(dst, src, size, u16, Efault);
-	probe_kernel_write_loop(dst, src, size, u8, Efault);
+	copy_to_kernel_nofault_loop(dst, src, size, u64, Efault);
+	copy_to_kernel_nofault_loop(dst, src, size, u32, Efault);
+	copy_to_kernel_nofault_loop(dst, src, size, u16, Efault);
+	copy_to_kernel_nofault_loop(dst, src, size, u8, Efault);
 	pagefault_enable();
 	return 0;
 Efault:
@@ -68,7 +68,7 @@ long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
 
 	if (unlikely(count <= 0))
 		return 0;
-	if (!probe_kernel_read_allowed(dst, unsafe_addr, count))
+	if (!copy_from_kernel_nofault_allowed(dst, unsafe_addr, count))
 		return -EFAULT;
 
 	pagefault_disable();
@@ -88,7 +88,7 @@ long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
 }
 #else /* HAVE_GET_KERNEL_NOFAULT */
 /**
- * probe_kernel_read(): safely attempt to read from kernel-space
+ * copy_from_kernel_nofault(): safely attempt to read from kernel-space
  * @dst: pointer to the buffer that shall take the data
  * @src: address to read from
  * @size: size of the data chunk
@@ -98,15 +98,15 @@ long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
  *
  * We ensure that the copy_from_user is executed in atomic context so that
  * do_page_fault() doesn't attempt to take mmap_sem.  This makes
- * probe_kernel_read() suitable for use within regions where the caller
+ * copy_from_kernel_nofault() suitable for use within regions where the caller
  * already holds mmap_sem, or other locks which nest inside mmap_sem.
  */
-long probe_kernel_read(void *dst, const void *src, size_t size)
+long copy_from_kernel_nofault(void *dst, const void *src, size_t size)
 {
 	long ret;
 	mm_segment_t old_fs = get_fs();
 
-	if (!probe_kernel_read_allowed(dst, src, size))
+	if (!copy_from_kernel_nofault_allowed(dst, src, size))
 		return -EFAULT;
 
 	set_fs(KERNEL_DS);
@@ -120,10 +120,10 @@ long probe_kernel_read(void *dst, const void *src, size_t size)
 		return -EFAULT;
 	return 0;
 }
-EXPORT_SYMBOL_GPL(probe_kernel_read);
+EXPORT_SYMBOL_GPL(copy_from_kernel_nofault);
 
 /**
- * probe_kernel_write(): safely attempt to write to a location
+ * copy_to_kernel_nofault(): safely attempt to write to a location
  * @dst: address to write to
  * @src: pointer to the data that shall be written
  * @size: size of the data chunk
@@ -131,7 +131,7 @@ EXPORT_SYMBOL_GPL(probe_kernel_read);
  * Safely write to address @dst from the buffer at @src.  If a kernel fault
  * happens, handle that and return -EFAULT.
  */
-long probe_kernel_write(void *dst, const void *src, size_t size)
+long copy_to_kernel_nofault(void *dst, const void *src, size_t size)
 {
 	long ret;
 	mm_segment_t old_fs = get_fs();
@@ -173,7 +173,7 @@ long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
 
 	if (unlikely(count <= 0))
 		return 0;
-	if (!probe_kernel_read_allowed(dst, unsafe_addr, count))
+	if (!copy_from_kernel_nofault_allowed(dst, unsafe_addr, count))
 		return -EFAULT;
 
 	set_fs(KERNEL_DS);
diff --git a/mm/rodata_test.c b/mm/rodata_test.c
index 5e313fa93276d..2a99df7beeb35 100644
--- a/mm/rodata_test.c
+++ b/mm/rodata_test.c
@@ -25,7 +25,7 @@ void rodata_test(void)
 	}
 
 	/* test 2: write to the variable; this should fault */
-	if (!probe_kernel_write((void *)&rodata_test_data,
+	if (!copy_to_kernel_nofault((void *)&rodata_test_data,
 				(void *)&zero, sizeof(zero))) {
 		pr_err("test data was not read only\n");
 		return;
diff --git a/mm/slub.c b/mm/slub.c
index b762450fc9f07..4af02f7af7118 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -292,7 +292,7 @@ static inline void *get_freepointer_safe(struct kmem_cache *s, void *object)
 		return get_freepointer(s, object);
 
 	freepointer_addr = (unsigned long)object + s->offset;
-	probe_kernel_read(&p, (void **)freepointer_addr, sizeof(p));
+	copy_from_kernel_nofault(&p, (void **)freepointer_addr, sizeof(p));
 	return freelist_ptr(s, p, freepointer_addr);
 }
 
-- 
2.26.2


^ permalink raw reply	[flat|nested] 33+ messages in thread

* [PATCH 18/20] maccess: rename probe_user_{read,write} to copy_{from,to}_user_nofault
  2020-05-19 13:44 clean up and streamline probe_kernel_* and friends v3 Christoph Hellwig
                   ` (16 preceding siblings ...)
  2020-05-19 13:44 ` [PATCH 17/20] maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault Christoph Hellwig
@ 2020-05-19 13:44 ` Christoph Hellwig
  2020-05-19 13:44 ` [PATCH 19/20] maccess: rename probe_kernel_address to get_kernel_nofault Christoph Hellwig
                   ` (2 subsequent siblings)
  20 siblings, 0 replies; 33+ messages in thread
From: Christoph Hellwig @ 2020-05-19 13:44 UTC (permalink / raw)
  To: x86, Alexei Starovoitov, Daniel Borkmann, Masami Hiramatsu,
	Linus Torvalds, Andrew Morton
  Cc: linux-parisc, linux-um, netdev, bpf, linux-mm, linux-kernel

Better describe what these functions do.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/powerpc/kernel/process.c          |  3 ++-
 arch/powerpc/kvm/book3s_64_mmu_radix.c |  4 ++--
 arch/powerpc/mm/fault.c                |  2 +-
 arch/powerpc/oprofile/backtrace.c      |  6 ++++--
 arch/powerpc/perf/callchain_32.c       |  2 +-
 arch/powerpc/perf/callchain_64.c       |  2 +-
 arch/powerpc/perf/core-book3s.c        |  3 ++-
 arch/powerpc/sysdev/fsl_pci.c          |  4 ++--
 include/linux/uaccess.h                |  4 ++--
 kernel/trace/bpf_trace.c               |  6 +++---
 kernel/trace/trace_kprobe.c            |  8 ++++----
 mm/maccess.c                           | 10 +++++-----
 12 files changed, 29 insertions(+), 25 deletions(-)

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 9c21288f86455..d5d6136b13480 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1294,7 +1294,8 @@ void show_user_instructions(struct pt_regs *regs)
 		for (i = 0; i < 8 && n; i++, n--, pc += sizeof(int)) {
 			int instr;
 
-			if (probe_user_read(&instr, (void __user *)pc, sizeof(instr))) {
+			if (copy_from_user_nofault(&instr, (void __user *)pc,
+					sizeof(instr))) {
 				seq_buf_printf(&s, "XXXXXXXX ");
 				continue;
 			}
diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c
index aa12cd4078b32..9d25f2eb5a33a 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_radix.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c
@@ -64,9 +64,9 @@ unsigned long __kvmhv_copy_tofrom_guest_radix(int lpid, int pid,
 	isync();
 
 	if (is_load)
-		ret = probe_user_read(to, (const void __user *)from, n);
+		ret = copy_from_user_nofault(to, (const void __user *)from, n);
 	else
-		ret = probe_user_write((void __user *)to, from, n);
+		ret = copy_to_user_nofault((void __user *)to, from, n);
 
 	/* switch the pid first to avoid running host with unallocated pid */
 	if (quadrant == 1 && pid != old_pid)
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 84af6c8eecf71..231664fe9d126 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -280,7 +280,7 @@ static bool bad_stack_expansion(struct pt_regs *regs, unsigned long address,
 		    access_ok(nip, sizeof(*nip))) {
 			unsigned int inst;
 
-			if (!probe_user_read(&inst, nip, sizeof(inst)))
+			if (!copy_from_user_nofault(&inst, nip, sizeof(inst)))
 				return !store_updates_sp(inst);
 			*must_retry = true;
 		}
diff --git a/arch/powerpc/oprofile/backtrace.c b/arch/powerpc/oprofile/backtrace.c
index 6f347fa29f41e..9db7ada79d10d 100644
--- a/arch/powerpc/oprofile/backtrace.c
+++ b/arch/powerpc/oprofile/backtrace.c
@@ -33,7 +33,8 @@ static unsigned int user_getsp32(unsigned int sp, int is_first)
 	 * which means that we've done all that we can do from
 	 * interrupt context.
 	 */
-	if (probe_user_read(stack_frame, (void __user *)p, sizeof(stack_frame)))
+	if (copy_from_user_nofault(stack_frame, (void __user *)p,
+			sizeof(stack_frame)))
 		return 0;
 
 	if (!is_first)
@@ -51,7 +52,8 @@ static unsigned long user_getsp64(unsigned long sp, int is_first)
 {
 	unsigned long stack_frame[3];
 
-	if (probe_user_read(stack_frame, (void __user *)sp, sizeof(stack_frame)))
+	if (copy_from_user_nofault(stack_frame, (void __user *)sp,
+			sizeof(stack_frame)))
 		return 0;
 
 	if (!is_first)
diff --git a/arch/powerpc/perf/callchain_32.c b/arch/powerpc/perf/callchain_32.c
index 8aa9510031415..2e21849f82b18 100644
--- a/arch/powerpc/perf/callchain_32.c
+++ b/arch/powerpc/perf/callchain_32.c
@@ -45,7 +45,7 @@ static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
 	    ((unsigned long)ptr & 3))
 		return -EFAULT;
 
-	rc = probe_user_read(ret, ptr, sizeof(*ret));
+	rc = copy_from_user_nofault(ret, ptr, sizeof(*ret));
 
 	if (IS_ENABLED(CONFIG_PPC64) && rc)
 		return read_user_stack_slow(ptr, ret, 4);
diff --git a/arch/powerpc/perf/callchain_64.c b/arch/powerpc/perf/callchain_64.c
index df1ffd8b20f21..7b0121694ebb7 100644
--- a/arch/powerpc/perf/callchain_64.c
+++ b/arch/powerpc/perf/callchain_64.c
@@ -71,7 +71,7 @@ static int read_user_stack_64(unsigned long __user *ptr, unsigned long *ret)
 	    ((unsigned long)ptr & 7))
 		return -EFAULT;
 
-	if (!probe_user_read(ret, ptr, sizeof(*ret)))
+	if (!copy_from_user_nofault(ret, ptr, sizeof(*ret)))
 		return 0;
 
 	return read_user_stack_slow(ptr, ret, 8);
diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
index 50bc9f0eb6be3..f8072d1e5d172 100644
--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c
@@ -426,7 +426,8 @@ static __u64 power_pmu_bhrb_to(u64 addr)
 	}
 
 	/* Userspace: need copy instruction here then translate it */
-	if (probe_user_read(&instr, (unsigned int __user *)addr, sizeof(instr)))
+	if (copy_from_user_nofault(&instr, (unsigned int __user *)addr,
+			sizeof(instr)))
 		return 0;
 
 	target = branch_target(&instr);
diff --git a/arch/powerpc/sysdev/fsl_pci.c b/arch/powerpc/sysdev/fsl_pci.c
index 4a8874bc10574..73fa37ca40ef9 100644
--- a/arch/powerpc/sysdev/fsl_pci.c
+++ b/arch/powerpc/sysdev/fsl_pci.c
@@ -1066,8 +1066,8 @@ int fsl_pci_mcheck_exception(struct pt_regs *regs)
 
 	if (is_in_pci_mem_space(addr)) {
 		if (user_mode(regs))
-			ret = probe_user_read(&inst, (void __user *)regs->nip,
-					      sizeof(inst));
+			ret = copy_from_user_nofault(&inst,
+					(void __user *)regs->nip, sizeof(inst));
 		else
 			ret = probe_kernel_address((void *)regs->nip, inst);
 
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index 849bc3dca54d6..baef2e09b5ae9 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -307,8 +307,8 @@ bool copy_from_kernel_nofault_allowed(void *dst, const void *unsafe_src,
 long copy_from_kernel_nofault(void *dst, const void *src, size_t size);
 long notrace copy_to_kernel_nofault(void *dst, const void *src, size_t size);
 
-extern long probe_user_read(void *dst, const void __user *src, size_t size);
-extern long notrace probe_user_write(void __user *dst, const void *src,
+long copy_from_user_nofault(void *dst, const void __user *src, size_t size);
+long notrace copy_to_user_nofault(void __user *dst, const void *src,
 		size_t size);
 
 long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr,
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 5b591d3b62af0..baccff18306cf 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -139,7 +139,7 @@ static const struct bpf_func_proto bpf_override_return_proto = {
 BPF_CALL_3(bpf_probe_read_user, void *, dst, u32, size,
 	   const void __user *, unsafe_ptr)
 {
-	int ret = probe_user_read(dst, unsafe_ptr, size);
+	int ret = copy_from_user_nofault(dst, unsafe_ptr, size);
 
 	if (unlikely(ret < 0))
 		memset(dst, 0, size);
@@ -188,7 +188,7 @@ bpf_probe_read_kernel_common(void *dst, u32 size, const void *unsafe_ptr,
 
 	if (IS_ENABLED(CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE) &&
 	    compat && (unsigned long)unsafe_ptr < TASK_SIZE)
-		ret = probe_user_read(dst, user_ptr, size);
+		ret = copy_from_user_nofault(dst, user_ptr, size);
 	else
 		ret = copy_from_kernel_nofault(dst, unsafe_ptr, size);
 	if (unlikely(ret < 0))
@@ -317,7 +317,7 @@ BPF_CALL_3(bpf_probe_write_user, void __user *, unsafe_ptr, const void *, src,
 	if (unlikely(!nmi_uaccess_okay()))
 		return -EPERM;
 
-	return probe_user_write(unsafe_ptr, src, size);
+	return copy_to_user_nofault(unsafe_ptr, src, size);
 }
 
 static const struct bpf_func_proto bpf_probe_write_user_proto = {
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index dab7c22d3e131..eb26b4c96b349 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1210,7 +1210,7 @@ fetch_store_strlen(unsigned long addr)
 	do {
 		if (IS_ENABLED(CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE) &&
 		    (unsigned long)addr < TASK_SIZE) {
-			ret = probe_user_read(&c,
+			ret = copy_from_user_nofault(&c,
 				(__force u8 __user *)addr + len, 1);
 		} else {
 			ret = copy_from_kernel_nofault(&c, (u8 *)addr + len, 1);
@@ -1292,8 +1292,8 @@ probe_mem_read(void *dest, void *src, size_t size)
 {
 	if (IS_ENABLED(CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE) &&
 	    (unsigned long)src < TASK_SIZE) {
-		return probe_user_read(dest, (__force const void __user *)src,
-				size);
+		return copy_from_user_nofault(dest,
+				(__force const void __user *)src, size);
 	}
 
 	return copy_from_kernel_nofault(dest, src, size);
@@ -1304,7 +1304,7 @@ probe_mem_read_user(void *dest, void *src, size_t size)
 {
 	const void __user *uaddr =  (__force const void __user *)src;
 
-	return probe_user_read(dest, uaddr, size);
+	return copy_from_user_nofault(dest, uaddr, size);
 }
 
 /* Note that we don't verify it, since the code does not come from user space */
diff --git a/mm/maccess.c b/mm/maccess.c
index 955b6c973f742..1e7d77656c596 100644
--- a/mm/maccess.c
+++ b/mm/maccess.c
@@ -192,7 +192,7 @@ long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
 #endif /* HAVE_GET_KERNEL_NOFAULT */
 
 /**
- * probe_user_read(): safely attempt to read from a user-space location
+ * copy_from_user_nofault(): safely attempt to read from a user-space location
  * @dst: pointer to the buffer that shall take the data
  * @src: address to read from. This must be a user address.
  * @size: size of the data chunk
@@ -200,7 +200,7 @@ long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
  * Safely read from user address @src to the buffer at @dst. If a kernel fault
  * happens, handle that and return -EFAULT.
  */
-long probe_user_read(void *dst, const void __user *src, size_t size)
+long copy_from_user_nofault(void *dst, const void __user *src, size_t size)
 {
 	long ret = -EFAULT;
 	mm_segment_t old_fs = get_fs();
@@ -217,10 +217,10 @@ long probe_user_read(void *dst, const void __user *src, size_t size)
 		return -EFAULT;
 	return 0;
 }
-EXPORT_SYMBOL_GPL(probe_user_read);
+EXPORT_SYMBOL_GPL(copy_from_user_nofault);
 
 /**
- * probe_user_write(): safely attempt to write to a user-space location
+ * copy_to_user_nofault(): safely attempt to write to a user-space location
  * @dst: address to write to
  * @src: pointer to the data that shall be written
  * @size: size of the data chunk
@@ -228,7 +228,7 @@ EXPORT_SYMBOL_GPL(probe_user_read);
  * Safely write to address @dst from the buffer at @src.  If a kernel fault
  * happens, handle that and return -EFAULT.
  */
-long probe_user_write(void __user *dst, const void *src, size_t size)
+long copy_to_user_nofault(void __user *dst, const void *src, size_t size)
 {
 	long ret = -EFAULT;
 	mm_segment_t old_fs = get_fs();
-- 
2.26.2


^ permalink raw reply	[flat|nested] 33+ messages in thread

* [PATCH 19/20] maccess: rename probe_kernel_address to get_kernel_nofault
  2020-05-19 13:44 clean up and streamline probe_kernel_* and friends v3 Christoph Hellwig
                   ` (17 preceding siblings ...)
  2020-05-19 13:44 ` [PATCH 18/20] maccess: rename probe_user_{read,write} to copy_{from,to}_user_nofault Christoph Hellwig
@ 2020-05-19 13:44 ` Christoph Hellwig
  2020-05-19 13:44 ` [PATCH 20/20] maccess: return -ERANGE when copy_from_kernel_nofault_allowed fails Christoph Hellwig
  2020-05-19 16:34 ` clean up and streamline probe_kernel_* and friends v3 Linus Torvalds
  20 siblings, 0 replies; 33+ messages in thread
From: Christoph Hellwig @ 2020-05-19 13:44 UTC (permalink / raw)
  To: x86, Alexei Starovoitov, Daniel Borkmann, Masami Hiramatsu,
	Linus Torvalds, Andrew Morton
  Cc: linux-parisc, linux-um, netdev, bpf, linux-mm, linux-kernel

Better describe what this helper does, and match the naming of
copy_from_kernel_nofault.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/arm/kernel/traps.c             |  2 +-
 arch/arm/mm/alignment.c             |  4 ++--
 arch/arm64/kernel/traps.c           |  2 +-
 arch/ia64/include/asm/sections.h    |  2 +-
 arch/parisc/kernel/process.c        |  2 +-
 arch/powerpc/include/asm/sections.h |  2 +-
 arch/powerpc/kernel/kgdb.c          |  2 +-
 arch/powerpc/kernel/process.c       |  2 +-
 arch/powerpc/sysdev/fsl_pci.c       |  2 +-
 arch/riscv/kernel/traps.c           |  4 ++--
 arch/s390/mm/fault.c                |  2 +-
 arch/sh/kernel/traps.c              |  2 +-
 arch/x86/kernel/probe_roms.c        | 20 ++++++++++----------
 arch/x86/kernel/traps.c             |  2 +-
 arch/x86/mm/fault.c                 |  6 +++---
 arch/x86/pci/pcbios.c               |  2 +-
 include/linux/uaccess.h             |  4 ++--
 lib/test_lockup.c                   |  6 +++---
 18 files changed, 34 insertions(+), 34 deletions(-)

diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index 1e70e7227f0ff..61b91872b3e74 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -391,7 +391,7 @@ int is_valid_bugaddr(unsigned long pc)
 	u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE);
 #endif
 
-	if (probe_kernel_address((unsigned *)pc, bkpt))
+	if (get_kernel_nofault((unsigned *)pc, bkpt))
 		return 0;
 
 	return bkpt == insn;
diff --git a/arch/arm/mm/alignment.c b/arch/arm/mm/alignment.c
index 84718eddae603..236016f13bcd3 100644
--- a/arch/arm/mm/alignment.c
+++ b/arch/arm/mm/alignment.c
@@ -774,7 +774,7 @@ static int alignment_get_arm(struct pt_regs *regs, u32 *ip, u32 *inst)
 	if (user_mode(regs))
 		fault = get_user(instr, ip);
 	else
-		fault = probe_kernel_address(ip, instr);
+		fault = get_kernel_nofault(ip, instr);
 
 	*inst = __mem_to_opcode_arm(instr);
 
@@ -789,7 +789,7 @@ static int alignment_get_thumb(struct pt_regs *regs, u16 *ip, u16 *inst)
 	if (user_mode(regs))
 		fault = get_user(instr, ip);
 	else
-		fault = probe_kernel_address(ip, instr);
+		fault = get_kernel_nofault(ip, instr);
 
 	*inst = __mem_to_opcode_thumb16(instr);
 
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index cf402be5c573f..2245af23973a2 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -315,7 +315,7 @@ static int call_undef_hook(struct pt_regs *regs)
 
 	if (!user_mode(regs)) {
 		__le32 instr_le;
-		if (probe_kernel_address((__force __le32 *)pc, instr_le))
+		if (get_kernel_nofault((__force __le32 *)pc, instr_le))
 			goto exit;
 		instr = le32_to_cpu(instr_le);
 	} else if (compat_thumb_mode(regs)) {
diff --git a/arch/ia64/include/asm/sections.h b/arch/ia64/include/asm/sections.h
index cea15f2dd38df..ef03eec8666f8 100644
--- a/arch/ia64/include/asm/sections.h
+++ b/arch/ia64/include/asm/sections.h
@@ -35,7 +35,7 @@ static inline void *dereference_function_descriptor(void *ptr)
 	struct fdesc *desc = ptr;
 	void *p;
 
-	if (!probe_kernel_address(&desc->ip, p))
+	if (!get_kernel_nofault(&desc->ip, p))
 		ptr = p;
 	return ptr;
 }
diff --git a/arch/parisc/kernel/process.c b/arch/parisc/kernel/process.c
index 230a6422b99f3..c3b0f03bd0bf1 100644
--- a/arch/parisc/kernel/process.c
+++ b/arch/parisc/kernel/process.c
@@ -293,7 +293,7 @@ void *dereference_function_descriptor(void *ptr)
 	Elf64_Fdesc *desc = ptr;
 	void *p;
 
-	if (!probe_kernel_address(&desc->addr, p))
+	if (!get_kernel_nofault(&desc->addr, p))
 		ptr = p;
 	return ptr;
 }
diff --git a/arch/powerpc/include/asm/sections.h b/arch/powerpc/include/asm/sections.h
index d19871763ed4a..636bb1633de18 100644
--- a/arch/powerpc/include/asm/sections.h
+++ b/arch/powerpc/include/asm/sections.h
@@ -85,7 +85,7 @@ static inline void *dereference_function_descriptor(void *ptr)
 	struct ppc64_opd_entry *desc = ptr;
 	void *p;
 
-	if (!probe_kernel_address(&desc->funcaddr, p))
+	if (!get_kernel_nofault(&desc->funcaddr, p))
 		ptr = p;
 	return ptr;
 }
diff --git a/arch/powerpc/kernel/kgdb.c b/arch/powerpc/kernel/kgdb.c
index 7dd55eb1259dc..f0045a74e7cea 100644
--- a/arch/powerpc/kernel/kgdb.c
+++ b/arch/powerpc/kernel/kgdb.c
@@ -420,7 +420,7 @@ int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
 	unsigned int instr;
 	unsigned int *addr = (unsigned int *)bpt->bpt_addr;
 
-	err = probe_kernel_address(addr, instr);
+	err = get_kernel_nofault(addr, instr);
 	if (err)
 		return err;
 
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index d5d6136b13480..b77f97073200c 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1260,7 +1260,7 @@ static void show_instructions(struct pt_regs *regs)
 #endif
 
 		if (!__kernel_text_address(pc) ||
-		    probe_kernel_address((const void *)pc, instr)) {
+		    get_kernel_nofault((const void *)pc, instr)) {
 			pr_cont("XXXXXXXX ");
 		} else {
 			if (regs->nip == pc)
diff --git a/arch/powerpc/sysdev/fsl_pci.c b/arch/powerpc/sysdev/fsl_pci.c
index 73fa37ca40ef9..483412d5a1973 100644
--- a/arch/powerpc/sysdev/fsl_pci.c
+++ b/arch/powerpc/sysdev/fsl_pci.c
@@ -1069,7 +1069,7 @@ int fsl_pci_mcheck_exception(struct pt_regs *regs)
 			ret = copy_from_user_nofault(&inst,
 					(void __user *)regs->nip, sizeof(inst));
 		else
-			ret = probe_kernel_address((void *)regs->nip, inst);
+			ret = get_kernel_nofault((void *)regs->nip, inst);
 
 		if (!ret && mcheck_handle_load(regs, inst)) {
 			regs->nip += 4;
diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
index 7f58fa53033f6..d807d507bd95a 100644
--- a/arch/riscv/kernel/traps.c
+++ b/arch/riscv/kernel/traps.c
@@ -137,7 +137,7 @@ static inline unsigned long get_break_insn_length(unsigned long pc)
 {
 	bug_insn_t insn;
 
-	if (probe_kernel_address((bug_insn_t *)pc, insn))
+	if (get_kernel_nofault((bug_insn_t *)pc, insn))
 		return 0;
 
 	return GET_INSN_LENGTH(insn);
@@ -160,7 +160,7 @@ int is_valid_bugaddr(unsigned long pc)
 
 	if (pc < VMALLOC_START)
 		return 0;
-	if (probe_kernel_address((bug_insn_t *)pc, insn))
+	if (get_kernel_nofault((bug_insn_t *)pc, insn))
 		return 0;
 	if ((insn & __INSN_LENGTH_MASK) == __INSN_LENGTH_32)
 		return (insn == __BUG_INSN_32);
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index dedc28be27ab4..ab68eca6b2480 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -106,7 +106,7 @@ static int bad_address(void *p)
 {
 	unsigned long dummy;
 
-	return probe_kernel_address((unsigned long *)p, dummy);
+	return get_kernel_nofault((unsigned long *)p, dummy);
 }
 
 static void dump_pagetable(unsigned long asce, unsigned long address)
diff --git a/arch/sh/kernel/traps.c b/arch/sh/kernel/traps.c
index 63cf17bc760da..27c53c5b84e6b 100644
--- a/arch/sh/kernel/traps.c
+++ b/arch/sh/kernel/traps.c
@@ -118,7 +118,7 @@ int is_valid_bugaddr(unsigned long addr)
 
 	if (addr < PAGE_OFFSET)
 		return 0;
-	if (probe_kernel_address((insn_size_t *)addr, opcode))
+	if (get_kernel_nofault((insn_size_t *)addr, opcode))
 		return 0;
 	if (opcode == TRAPA_BUG_OPCODE)
 		return 1;
diff --git a/arch/x86/kernel/probe_roms.c b/arch/x86/kernel/probe_roms.c
index ee0286390a4c1..77f3341570e84 100644
--- a/arch/x86/kernel/probe_roms.c
+++ b/arch/x86/kernel/probe_roms.c
@@ -99,7 +99,7 @@ static bool probe_list(struct pci_dev *pdev, unsigned short vendor,
 	unsigned short device;
 
 	do {
-		if (probe_kernel_address(rom_list, device) != 0)
+		if (get_kernel_nofault(rom_list, device) != 0)
 			device = 0;
 
 		if (device && match_id(pdev, vendor, device))
@@ -125,13 +125,13 @@ static struct resource *find_oprom(struct pci_dev *pdev)
 			break;
 
 		rom = isa_bus_to_virt(res->start);
-		if (probe_kernel_address(rom + 0x18, offset) != 0)
+		if (get_kernel_nofault(rom + 0x18, offset) != 0)
 			continue;
 
-		if (probe_kernel_address(rom + offset + 0x4, vendor) != 0)
+		if (get_kernel_nofault(rom + offset + 0x4, vendor) != 0)
 			continue;
 
-		if (probe_kernel_address(rom + offset + 0x6, device) != 0)
+		if (get_kernel_nofault(rom + offset + 0x6, device) != 0)
 			continue;
 
 		if (match_id(pdev, vendor, device)) {
@@ -139,8 +139,8 @@ static struct resource *find_oprom(struct pci_dev *pdev)
 			break;
 		}
 
-		if (probe_kernel_address(rom + offset + 0x8, list) == 0 &&
-		    probe_kernel_address(rom + offset + 0xc, rev) == 0 &&
+		if (get_kernel_nofault(rom + offset + 0x8, list) == 0 &&
+		    get_kernel_nofault(rom + offset + 0xc, rev) == 0 &&
 		    rev >= 3 && list &&
 		    probe_list(pdev, vendor, rom + offset + list)) {
 			oprom = res;
@@ -183,14 +183,14 @@ static int __init romsignature(const unsigned char *rom)
 	const unsigned short * const ptr = (const unsigned short *)rom;
 	unsigned short sig;
 
-	return probe_kernel_address(ptr, sig) == 0 && sig == ROMSIGNATURE;
+	return get_kernel_nofault(ptr, sig) == 0 && sig == ROMSIGNATURE;
 }
 
 static int __init romchecksum(const unsigned char *rom, unsigned long length)
 {
 	unsigned char sum, c;
 
-	for (sum = 0; length && probe_kernel_address(rom++, c) == 0; length--)
+	for (sum = 0; length && get_kernel_nofault(rom++, c) == 0; length--)
 		sum += c;
 	return !length && !sum;
 }
@@ -211,7 +211,7 @@ void __init probe_roms(void)
 
 		video_rom_resource.start = start;
 
-		if (probe_kernel_address(rom + 2, c) != 0)
+		if (get_kernel_nofault(rom + 2, c) != 0)
 			continue;
 
 		/* 0 < length <= 0x7f * 512, historically */
@@ -249,7 +249,7 @@ void __init probe_roms(void)
 		if (!romsignature(rom))
 			continue;
 
-		if (probe_kernel_address(rom + 2, c) != 0)
+		if (get_kernel_nofault(rom + 2, c) != 0)
 			continue;
 
 		/* 0 < length <= 0x7f * 512, historically */
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 96809f6aad67d..07739b67da335 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -161,7 +161,7 @@ int is_valid_bugaddr(unsigned long addr)
 	if (addr < TASK_SIZE_MAX)
 		return 0;
 
-	if (probe_kernel_address((unsigned short *)addr, ud))
+	if (get_kernel_nofault((unsigned short *)addr, ud))
 		return 0;
 
 	return ud == INSN_UD0 || ud == INSN_UD2;
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 994e207abdf64..7c5e23e7407d8 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -98,7 +98,7 @@ check_prefetch_opcode(struct pt_regs *regs, unsigned char *instr,
 		return !instr_lo || (instr_lo>>1) == 1;
 	case 0x00:
 		/* Prefetch instruction is 0x0F0D or 0x0F18 */
-		if (probe_kernel_address(instr, opcode))
+		if (get_kernel_nofault(instr, opcode))
 			return 0;
 
 		*prefetch = (instr_lo == 0xF) &&
@@ -132,7 +132,7 @@ is_prefetch(struct pt_regs *regs, unsigned long error_code, unsigned long addr)
 	while (instr < max_instr) {
 		unsigned char opcode;
 
-		if (probe_kernel_address(instr, opcode))
+		if (get_kernel_nofault(instr, opcode))
 			break;
 
 		instr++;
@@ -441,7 +441,7 @@ static int bad_address(void *p)
 {
 	unsigned long dummy;
 
-	return probe_kernel_address((unsigned long *)p, dummy);
+	return get_kernel_nofault((unsigned long *)p, dummy);
 }
 
 static void dump_pagetable(unsigned long address)
diff --git a/arch/x86/pci/pcbios.c b/arch/x86/pci/pcbios.c
index 9c97d814125eb..b7f8699b18c1f 100644
--- a/arch/x86/pci/pcbios.c
+++ b/arch/x86/pci/pcbios.c
@@ -302,7 +302,7 @@ static const struct pci_raw_ops *__init pci_find_bios(void)
 	     check <= (union bios32 *) __va(0xffff0);
 	     ++check) {
 		long sig;
-		if (probe_kernel_address(&check->fields.signature, sig))
+		if (get_kernel_nofault(&check->fields.signature, sig))
 			continue;
 
 		if (check->fields.signature != BIOS32_SIGNATURE)
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index baef2e09b5ae9..5cc94a38a3984 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -319,13 +319,13 @@ long strncpy_from_user_nofault(char *dst, const void __user *unsafe_addr,
 long strnlen_user_nofault(const void __user *unsafe_addr, long count);
 
 /**
- * probe_kernel_address(): safely attempt to read from a location
+ * get_kernel_nofault(): safely attempt to read from a location
  * @addr: address to read from
  * @retval: read into this variable
  *
  * Returns 0 on success, or -EFAULT.
  */
-#define probe_kernel_address(addr, retval)		\
+#define get_kernel_nofault(addr, retval)		\
 	copy_from_kernel_nofault(&retval, addr, sizeof(retval))
 
 #ifndef user_access_begin
diff --git a/lib/test_lockup.c b/lib/test_lockup.c
index ea09ca335b214..71f7a4c89ed4f 100644
--- a/lib/test_lockup.c
+++ b/lib/test_lockup.c
@@ -419,8 +419,8 @@ static bool test_kernel_ptr(unsigned long addr, int size)
 	/* should be at least readable kernel address */
 	if (access_ok(ptr, 1) ||
 	    access_ok(ptr + size - 1, 1) ||
-	    probe_kernel_address(ptr, buf) ||
-	    probe_kernel_address(ptr + size - 1, buf)) {
+	    get_kernel_nofault(ptr, buf) ||
+	    get_kernel_nofault(ptr + size - 1, buf)) {
 		pr_err("invalid kernel ptr: %#lx\n", addr);
 		return true;
 	}
@@ -437,7 +437,7 @@ static bool __maybe_unused test_magic(unsigned long addr, int offset,
 	if (!addr)
 		return false;
 
-	if (probe_kernel_address(ptr, magic) || magic != expected) {
+	if (get_kernel_nofault(ptr, magic) || magic != expected) {
 		pr_err("invalid magic at %#lx + %#x = %#x, expected %#x\n",
 		       addr, offset, magic, expected);
 		return true;
-- 
2.26.2


^ permalink raw reply	[flat|nested] 33+ messages in thread

* [PATCH 20/20] maccess: return -ERANGE when copy_from_kernel_nofault_allowed fails
  2020-05-19 13:44 clean up and streamline probe_kernel_* and friends v3 Christoph Hellwig
                   ` (18 preceding siblings ...)
  2020-05-19 13:44 ` [PATCH 19/20] maccess: rename probe_kernel_address to get_kernel_nofault Christoph Hellwig
@ 2020-05-19 13:44 ` Christoph Hellwig
  2020-05-20 11:02   ` Masami Hiramatsu
  2020-05-19 16:34 ` clean up and streamline probe_kernel_* and friends v3 Linus Torvalds
  20 siblings, 1 reply; 33+ messages in thread
From: Christoph Hellwig @ 2020-05-19 13:44 UTC (permalink / raw)
  To: x86, Alexei Starovoitov, Daniel Borkmann, Masami Hiramatsu,
	Linus Torvalds, Andrew Morton
  Cc: linux-parisc, linux-um, netdev, bpf, linux-mm, linux-kernel

Allow the callers to distinguish a real unmapped address vs a range
that can't be probed.

Suggested-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/maccess.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/mm/maccess.c b/mm/maccess.c
index 1e7d77656c596..4010d64189d21 100644
--- a/mm/maccess.c
+++ b/mm/maccess.c
@@ -25,7 +25,7 @@ bool __weak copy_from_kernel_nofault_allowed(void *dst, const void *unsafe_src,
 long copy_from_kernel_nofault(void *dst, const void *src, size_t size)
 {
 	if (!copy_from_kernel_nofault_allowed(dst, src, size))
-		return -EFAULT;
+		return -ERANGE;
 
 	pagefault_disable();
 	copy_from_kernel_nofault_loop(dst, src, size, u64, Efault);
@@ -69,7 +69,7 @@ long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
 	if (unlikely(count <= 0))
 		return 0;
 	if (!copy_from_kernel_nofault_allowed(dst, unsafe_addr, count))
-		return -EFAULT;
+		return -ERANGE;
 
 	pagefault_disable();
 	do {
@@ -107,7 +107,7 @@ long copy_from_kernel_nofault(void *dst, const void *src, size_t size)
 	mm_segment_t old_fs = get_fs();
 
 	if (!copy_from_kernel_nofault_allowed(dst, src, size))
-		return -EFAULT;
+		return -ERANGE;
 
 	set_fs(KERNEL_DS);
 	pagefault_disable();
@@ -174,7 +174,7 @@ long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
 	if (unlikely(count <= 0))
 		return 0;
 	if (!copy_from_kernel_nofault_allowed(dst, unsafe_addr, count))
-		return -EFAULT;
+		return -ERANGE;
 
 	set_fs(KERNEL_DS);
 	pagefault_disable();
-- 
2.26.2


^ permalink raw reply	[flat|nested] 33+ messages in thread

* Re: [PATCH 11/20] bpf: factor out a bpf_trace_copy_string helper
  2020-05-19 13:44 ` [PATCH 11/20] bpf: factor out a bpf_trace_copy_string helper Christoph Hellwig
@ 2020-05-19 16:07   ` Linus Torvalds
  2020-05-19 16:14     ` Christoph Hellwig
  0 siblings, 1 reply; 33+ messages in thread
From: Linus Torvalds @ 2020-05-19 16:07 UTC (permalink / raw)
  To: Christoph Hellwig
  Cc: the arch/x86 maintainers, Alexei Starovoitov, Daniel Borkmann,
	Masami Hiramatsu, Andrew Morton, linux-parisc, linux-um, Netdev,
	bpf, Linux-MM, Linux Kernel Mailing List

On Tue, May 19, 2020 at 6:45 AM Christoph Hellwig <hch@lst.de> wrote:
>
> +       switch (fmt_ptype) {
> +       case 's':
> +#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
> +               strncpy_from_unsafe(buf, unsafe_ptr, bufsz);
> +               break;
> +#endif
> +       case 'k':
> +               strncpy_from_kernel_nofault(buf, unsafe_ptr, bufsz);
> +               break;

That 's' case needs a "fallthrough;" for the overlapping case,
methinks. Otherwise you'll get warnings.

                  Linus

^ permalink raw reply	[flat|nested] 33+ messages in thread

* Re: [PATCH 11/20] bpf: factor out a bpf_trace_copy_string helper
  2020-05-19 16:07   ` Linus Torvalds
@ 2020-05-19 16:14     ` Christoph Hellwig
  2020-05-19 16:36       ` Linus Torvalds
  0 siblings, 1 reply; 33+ messages in thread
From: Christoph Hellwig @ 2020-05-19 16:14 UTC (permalink / raw)
  To: Linus Torvalds
  Cc: Christoph Hellwig, the arch/x86 maintainers, Alexei Starovoitov,
	Daniel Borkmann, Masami Hiramatsu, Andrew Morton, linux-parisc,
	linux-um, Netdev, bpf, Linux-MM, Linux Kernel Mailing List

On Tue, May 19, 2020 at 09:07:55AM -0700, Linus Torvalds wrote:
> On Tue, May 19, 2020 at 6:45 AM Christoph Hellwig <hch@lst.de> wrote:
> >
> > +       switch (fmt_ptype) {
> > +       case 's':
> > +#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
> > +               strncpy_from_unsafe(buf, unsafe_ptr, bufsz);
> > +               break;
> > +#endif
> > +       case 'k':
> > +               strncpy_from_kernel_nofault(buf, unsafe_ptr, bufsz);
> > +               break;
> 
> That 's' case needs a "fallthrough;" for the overlapping case,
> methinks. Otherwise you'll get warnings.

I don't think we need it as the case of

	case 'a':
	case 'b':
		do_stuff();
		break;

has always been fine even with the fallthough warnings.  And the
rest of the stuff gets removed by cpp..

^ permalink raw reply	[flat|nested] 33+ messages in thread

* Re: [PATCH 12/20] maccess: remove strncpy_from_unsafe
  2020-05-19 13:44 ` [PATCH 12/20] maccess: remove strncpy_from_unsafe Christoph Hellwig
@ 2020-05-19 16:25   ` Linus Torvalds
  2020-05-19 16:41     ` Christoph Hellwig
  0 siblings, 1 reply; 33+ messages in thread
From: Linus Torvalds @ 2020-05-19 16:25 UTC (permalink / raw)
  To: Christoph Hellwig
  Cc: the arch/x86 maintainers, Alexei Starovoitov, Daniel Borkmann,
	Masami Hiramatsu, Andrew Morton, linux-parisc, linux-um, Netdev,
	bpf, Linux-MM, Linux Kernel Mailing List

On Tue, May 19, 2020 at 6:45 AM Christoph Hellwig <hch@lst.de> wrote:
>
> +       if (IS_ENABLED(CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE) &&
> +           compat && (unsigned long)unsafe_ptr < TASK_SIZE)
> +               ret = strncpy_from_user_nofault(dst, user_ptr, size);
> +       else
> +               ret = strncpy_from_kernel_nofault(dst, unsafe_ptr, size);

These conditionals are completely illegible.

That's true in the next patch too.

Stop using "IS_ENABLED(config)" to make very complex conditionals.

A clear #ifdef is much better if the alternative is a conditional that
is completely impossible to actually understand and needs multiple
lines to read.

If you made this a simple helper (called "bpf_strncpy_from_unsafe()"
with that "compat" flag, perhaps?), it would be much more legible as

  /*
   * Big comment goes here about the compat behavior and
   * non-overlapping address spaces and ambiguous pointers.
   */
  static long bpf_strncpy_from_legacy(void *dest, const void
*unsafe_ptr, long size, bool legacy)
  {
  #ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
        if (legacy && addr < TASK_SIZE)
            return strncpy_from_user_nofault(dst, (const void __user
*) unsafe_ptr, size);
  #endif

        return strncpy_from_kernel_nofault(dst, unsafe_ptr, size);
  }

and then you'd just use

        if (bpf_strncpy_from_unsafe(dst, unsafe_ptr, size, compat) < 0)
                memset(dst, 0, size);

and avoid any complicated conditionals, goto's, and make the code much
easier to understand thanks to having a big comment about the legacy
case.

In fact, separately I'd probably want that "compat" naming to be
scrapped entirely in that file.

"compat" generally means something very specific and completely
different in the kernel: it's the "I'm a 32-bit binary on a 64-bit
kernel" compatibility case.

Here, it's literally "BPF legacy behavior", not that kind of "compat" thing.

But that renaming is separate, although I'd start the ball rolling
with that "bpf_strncpy_from_legacy()" helper.

                Linus

^ permalink raw reply	[flat|nested] 33+ messages in thread

* Re: [PATCH 13/20] maccess: always use strict semantics for probe_kernel_read
  2020-05-19 13:44 ` [PATCH 13/20] maccess: always use strict semantics for probe_kernel_read Christoph Hellwig
@ 2020-05-19 16:33   ` Linus Torvalds
  2020-05-20 11:11   ` Masami Hiramatsu
  1 sibling, 0 replies; 33+ messages in thread
From: Linus Torvalds @ 2020-05-19 16:33 UTC (permalink / raw)
  To: Christoph Hellwig
  Cc: the arch/x86 maintainers, Alexei Starovoitov, Daniel Borkmann,
	Masami Hiramatsu, Andrew Morton, linux-parisc, linux-um, Netdev,
	bpf, Linux-MM, Linux Kernel Mailing List

On Tue, May 19, 2020 at 6:45 AM Christoph Hellwig <hch@lst.de> wrote:
>
> +
> +       if (IS_ENABLED(CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE) &&
> +           compat && (unsigned long)unsafe_ptr < TASK_SIZE)
> +               ret = probe_user_read(dst, user_ptr, size);
> +       else
> +               ret = probe_kernel_read(dst, unsafe_ptr, size);
...
> -               ret = probe_kernel_read(&c, (u8 *)addr + len, 1);
> +               if (IS_ENABLED(CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE) &&
> +                   (unsigned long)addr < TASK_SIZE) {
> +                       ret = probe_user_read(&c,
> +                               (__force u8 __user *)addr + len, 1);
> +               } else {
> +                       ret = probe_kernel_read(&c, (u8 *)addr + len, 1);
> +               }
...
> +       if (IS_ENABLED(CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE) &&
> +           (unsigned long)src < TASK_SIZE) {
> +               return probe_user_read(dest, (__force const void __user *)src,
> +                               size);

If you can't make the conditional legible and fit on a single line and
make it obvious _why_ you have that conditional, just use a helper
function.

Either for just the conditional itself, or for the whole operation.
And at least for the bpf case, since you want the whole operation for
that error handling and clearing of the result buffer anyway, I
suspect it would be cleaner to have that kind of
"bpf_copy_legacy_nofault()" function or whatever.

(And see previous email why I dislike that "compat" naming in the bpf case)

                    Linus

^ permalink raw reply	[flat|nested] 33+ messages in thread

* Re: clean up and streamline probe_kernel_* and friends v3
  2020-05-19 13:44 clean up and streamline probe_kernel_* and friends v3 Christoph Hellwig
                   ` (19 preceding siblings ...)
  2020-05-19 13:44 ` [PATCH 20/20] maccess: return -ERANGE when copy_from_kernel_nofault_allowed fails Christoph Hellwig
@ 2020-05-19 16:34 ` Linus Torvalds
  20 siblings, 0 replies; 33+ messages in thread
From: Linus Torvalds @ 2020-05-19 16:34 UTC (permalink / raw)
  To: Christoph Hellwig
  Cc: the arch/x86 maintainers, Alexei Starovoitov, Daniel Borkmann,
	Masami Hiramatsu, Andrew Morton, linux-parisc, linux-um, Netdev,
	bpf, Linux-MM, Linux Kernel Mailing List

On Tue, May 19, 2020 at 6:44 AM Christoph Hellwig <hch@lst.de> wrote:
>
>  - rebased on 5.7-rc6 with the bpf trace format string changes

Other than the critique about illegible conditionals in the result
when doing that bpf/trace conversion, I like it.

                  Linus

^ permalink raw reply	[flat|nested] 33+ messages in thread

* Re: [PATCH 11/20] bpf: factor out a bpf_trace_copy_string helper
  2020-05-19 16:14     ` Christoph Hellwig
@ 2020-05-19 16:36       ` Linus Torvalds
  0 siblings, 0 replies; 33+ messages in thread
From: Linus Torvalds @ 2020-05-19 16:36 UTC (permalink / raw)
  To: Christoph Hellwig
  Cc: the arch/x86 maintainers, Alexei Starovoitov, Daniel Borkmann,
	Masami Hiramatsu, Andrew Morton, linux-parisc, linux-um, Netdev,
	bpf, Linux-MM, Linux Kernel Mailing List

On Tue, May 19, 2020 at 9:14 AM Christoph Hellwig <hch@lst.de> wrote:
>
> I don't think we need it as the case of
>
>         case 'a':
>         case 'b':
>                 do_stuff();
>                 break;
>
> has always been fine even with the fallthough warnings.  And the
> rest of the stuff gets removed by cpp..

You're right. I read it as a fallthrough because as a human it looks
like there's code in there between, but yeah, the compiler won't
actually ever see it.

So scratch that objection.

              Linus

^ permalink raw reply	[flat|nested] 33+ messages in thread

* Re: [PATCH 12/20] maccess: remove strncpy_from_unsafe
  2020-05-19 16:25   ` Linus Torvalds
@ 2020-05-19 16:41     ` Christoph Hellwig
  2020-05-19 16:46       ` Linus Torvalds
  0 siblings, 1 reply; 33+ messages in thread
From: Christoph Hellwig @ 2020-05-19 16:41 UTC (permalink / raw)
  To: Linus Torvalds
  Cc: Christoph Hellwig, the arch/x86 maintainers, Alexei Starovoitov,
	Daniel Borkmann, Masami Hiramatsu, Andrew Morton, linux-parisc,
	linux-um, Netdev, bpf, Linux-MM, Linux Kernel Mailing List

On Tue, May 19, 2020 at 09:25:57AM -0700, Linus Torvalds wrote:
> On Tue, May 19, 2020 at 6:45 AM Christoph Hellwig <hch@lst.de> wrote:
> >
> > +       if (IS_ENABLED(CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE) &&
> > +           compat && (unsigned long)unsafe_ptr < TASK_SIZE)
> > +               ret = strncpy_from_user_nofault(dst, user_ptr, size);
> > +       else
> > +               ret = strncpy_from_kernel_nofault(dst, unsafe_ptr, size);
> 
> These conditionals are completely illegible.

I had a lot of folks complaining about things like:

#ifdef CONFIG_FOO
	if (foo)
		do_stuff();
	else
#endif
		do_something_else();

which I personally don't mind at all, so I switched to this style.

>   static long bpf_strncpy_from_legacy(void *dest, const void
> *unsafe_ptr, long size, bool legacy)
>   {
>   #ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
>         if (legacy && addr < TASK_SIZE)
>             return strncpy_from_user_nofault(dst, (const void __user
> *) unsafe_ptr, size);
>   #endif
> 
>         return strncpy_from_kernel_nofault(dst, unsafe_ptr, size);
>   }
> 
> and then you'd just use
> 
>         if (bpf_strncpy_from_unsafe(dst, unsafe_ptr, size, compat) < 0)
>                 memset(dst, 0, size);
> 
> and avoid any complicated conditionals, goto's, and make the code much
> easier to understand thanks to having a big comment about the legacy
> case.

Sure.

> In fact, separately I'd probably want that "compat" naming to be
> scrapped entirely in that file.

Not my choice..  Maybe Daniel has a recommendation of what to change
there, but I'd love to not have to deal with that renaming as well
in this series.

^ permalink raw reply	[flat|nested] 33+ messages in thread

* Re: [PATCH 12/20] maccess: remove strncpy_from_unsafe
  2020-05-19 16:41     ` Christoph Hellwig
@ 2020-05-19 16:46       ` Linus Torvalds
  0 siblings, 0 replies; 33+ messages in thread
From: Linus Torvalds @ 2020-05-19 16:46 UTC (permalink / raw)
  To: Christoph Hellwig
  Cc: the arch/x86 maintainers, Alexei Starovoitov, Daniel Borkmann,
	Masami Hiramatsu, Andrew Morton, linux-parisc, linux-um, Netdev,
	bpf, Linux-MM, Linux Kernel Mailing List

On Tue, May 19, 2020 at 9:41 AM Christoph Hellwig <hch@lst.de> wrote:
>
> I had a lot of folks complaining about things like:
>
> #ifdef CONFIG_FOO
>         if (foo)
>                 do_stuff();
>         else
> #endif
>                 do_something_else();
>
> which I personally don't mind at all, so I switched to this style.

Well, I don't particularly like that style either, it is _very_ easy
to get wrong when you edit it later (and various indentation checkers
tend to be very unhappy about it too).

But that's why I like trying to just make simple helper functions instead.

Yeah, it's often a few more lines of code (if only because of the
extra function definition etc), but with good naming and sane
arguments those few extra lines can also help make it much more
understandable in the process, and it gives you a nice place to add
commentary for the really odd cases (comments inside code that then
does other things often make things just harder to see).

             Linus

^ permalink raw reply	[flat|nested] 33+ messages in thread

* Re: [PATCH 20/20] maccess: return -ERANGE when copy_from_kernel_nofault_allowed fails
  2020-05-19 13:44 ` [PATCH 20/20] maccess: return -ERANGE when copy_from_kernel_nofault_allowed fails Christoph Hellwig
@ 2020-05-20 11:02   ` Masami Hiramatsu
  2020-05-20 16:16     ` Christoph Hellwig
  0 siblings, 1 reply; 33+ messages in thread
From: Masami Hiramatsu @ 2020-05-20 11:02 UTC (permalink / raw)
  To: Christoph Hellwig
  Cc: x86, Alexei Starovoitov, Daniel Borkmann, Linus Torvalds,
	Andrew Morton, linux-parisc, linux-um, netdev, bpf, linux-mm,
	linux-kernel

On Tue, 19 May 2020 15:44:49 +0200
Christoph Hellwig <hch@lst.de> wrote:

> Allow the callers to distinguish a real unmapped address vs a range
> that can't be probed.
> 
> Suggested-by: Masami Hiramatsu <mhiramat@kernel.org>
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Hi Christoph,

Can you also update the kerneldoc comment too?
Other than that, this looks good to me.

Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>

Thank you!

> ---
>  mm/maccess.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/mm/maccess.c b/mm/maccess.c
> index 1e7d77656c596..4010d64189d21 100644
> --- a/mm/maccess.c
> +++ b/mm/maccess.c
> @@ -25,7 +25,7 @@ bool __weak copy_from_kernel_nofault_allowed(void *dst, const void *unsafe_src,
>  long copy_from_kernel_nofault(void *dst, const void *src, size_t size)
>  {
>  	if (!copy_from_kernel_nofault_allowed(dst, src, size))
> -		return -EFAULT;
> +		return -ERANGE;
>  
>  	pagefault_disable();
>  	copy_from_kernel_nofault_loop(dst, src, size, u64, Efault);
> @@ -69,7 +69,7 @@ long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
>  	if (unlikely(count <= 0))
>  		return 0;
>  	if (!copy_from_kernel_nofault_allowed(dst, unsafe_addr, count))
> -		return -EFAULT;
> +		return -ERANGE;
>  
>  	pagefault_disable();
>  	do {
> @@ -107,7 +107,7 @@ long copy_from_kernel_nofault(void *dst, const void *src, size_t size)
>  	mm_segment_t old_fs = get_fs();
>  
>  	if (!copy_from_kernel_nofault_allowed(dst, src, size))
> -		return -EFAULT;
> +		return -ERANGE;
>  
>  	set_fs(KERNEL_DS);
>  	pagefault_disable();
> @@ -174,7 +174,7 @@ long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
>  	if (unlikely(count <= 0))
>  		return 0;
>  	if (!copy_from_kernel_nofault_allowed(dst, unsafe_addr, count))
> -		return -EFAULT;
> +		return -ERANGE;
>  
>  	set_fs(KERNEL_DS);
>  	pagefault_disable();
> -- 
> 2.26.2
> 


-- 
Masami Hiramatsu <mhiramat@kernel.org>

^ permalink raw reply	[flat|nested] 33+ messages in thread

* Re: [PATCH 13/20] maccess: always use strict semantics for probe_kernel_read
  2020-05-19 13:44 ` [PATCH 13/20] maccess: always use strict semantics for probe_kernel_read Christoph Hellwig
  2020-05-19 16:33   ` Linus Torvalds
@ 2020-05-20 11:11   ` Masami Hiramatsu
  2020-05-20 11:13     ` Christoph Hellwig
  1 sibling, 1 reply; 33+ messages in thread
From: Masami Hiramatsu @ 2020-05-20 11:11 UTC (permalink / raw)
  To: Christoph Hellwig
  Cc: x86, Alexei Starovoitov, Daniel Borkmann, Linus Torvalds,
	Andrew Morton, linux-parisc, linux-um, netdev, bpf, linux-mm,
	linux-kernel

On Tue, 19 May 2020 15:44:42 +0200
Christoph Hellwig <hch@lst.de> wrote:

> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> index 2f6737cc53e6c..82da20e712507 100644
> --- a/kernel/trace/trace_kprobe.c
> +++ b/kernel/trace/trace_kprobe.c
> @@ -1208,7 +1208,13 @@ fetch_store_strlen(unsigned long addr)
>  	u8 c;
>  
>  	do {
> -		ret = probe_kernel_read(&c, (u8 *)addr + len, 1);
> +		if (IS_ENABLED(CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE) &&
> +		    (unsigned long)addr < TASK_SIZE) {
> +			ret = probe_user_read(&c,
> +				(__force u8 __user *)addr + len, 1);
> +		} else {
> +			ret = probe_kernel_read(&c, (u8 *)addr + len, 1);
> +		}
>  		len++;
>  	} while (c && ret == 0 && len < MAX_STRING_SIZE);

To avoid redundant check in the loop, we can use strnlen_user_nofault() out of
the loop. Something like below.

...
	u8 c;

	if (IS_ENABLED(CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE) &&
	    (unsigned long)addr < TASK_SIZE) {
		return strnlen_user_nofault((__force u8 __user *)addr, MAX_STRING_SIZE);

	do {
		ret = probe_kernel_read(&c, (u8 *)addr + len, 1);
		len++;
	} while (c && ret == 0 && len < MAX_STRING_SIZE);
...

This must work because we must not have a string that continues across
kernel space and user space.

Thank you,


-- 
Masami Hiramatsu <mhiramat@kernel.org>

^ permalink raw reply	[flat|nested] 33+ messages in thread

* Re: [PATCH 13/20] maccess: always use strict semantics for probe_kernel_read
  2020-05-20 11:11   ` Masami Hiramatsu
@ 2020-05-20 11:13     ` Christoph Hellwig
  0 siblings, 0 replies; 33+ messages in thread
From: Christoph Hellwig @ 2020-05-20 11:13 UTC (permalink / raw)
  To: Masami Hiramatsu
  Cc: Christoph Hellwig, x86, Alexei Starovoitov, Daniel Borkmann,
	Linus Torvalds, Andrew Morton, linux-parisc, linux-um, netdev,
	bpf, linux-mm, linux-kernel

On Wed, May 20, 2020 at 08:11:26PM +0900, Masami Hiramatsu wrote:
> > -		ret = probe_kernel_read(&c, (u8 *)addr + len, 1);
> > +		if (IS_ENABLED(CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE) &&
> > +		    (unsigned long)addr < TASK_SIZE) {
> > +			ret = probe_user_read(&c,
> > +				(__force u8 __user *)addr + len, 1);
> > +		} else {
> > +			ret = probe_kernel_read(&c, (u8 *)addr + len, 1);
> > +		}
> >  		len++;
> >  	} while (c && ret == 0 && len < MAX_STRING_SIZE);
> 
> To avoid redundant check in the loop, we can use strnlen_user_nofault() out of
> the loop. Something like below.

Yes, I've done something very similar in response to Linus' comment (just
using an ifdef instead).

^ permalink raw reply	[flat|nested] 33+ messages in thread

* Re: [PATCH 20/20] maccess: return -ERANGE when copy_from_kernel_nofault_allowed fails
  2020-05-20 11:02   ` Masami Hiramatsu
@ 2020-05-20 16:16     ` Christoph Hellwig
  0 siblings, 0 replies; 33+ messages in thread
From: Christoph Hellwig @ 2020-05-20 16:16 UTC (permalink / raw)
  To: Masami Hiramatsu
  Cc: Christoph Hellwig, x86, Alexei Starovoitov, Daniel Borkmann,
	Linus Torvalds, Andrew Morton, linux-parisc, linux-um, netdev,
	bpf, linux-mm, linux-kernel

On Wed, May 20, 2020 at 08:02:55PM +0900, Masami Hiramatsu wrote:
> Can you also update the kerneldoc comment too?

Sure, done.

^ permalink raw reply	[flat|nested] 33+ messages in thread

end of thread, back to index

Thread overview: 33+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-05-19 13:44 clean up and streamline probe_kernel_* and friends v3 Christoph Hellwig
2020-05-19 13:44 ` [PATCH 01/20] maccess: unexport probe_kernel_write and probe_user_write Christoph Hellwig
2020-05-19 13:44 ` [PATCH 02/20] maccess: remove various unused weak aliases Christoph Hellwig
2020-05-19 13:44 ` [PATCH 03/20] maccess: remove duplicate kerneldoc comments Christoph Hellwig
2020-05-19 13:44 ` [PATCH 04/20] maccess: clarify " Christoph Hellwig
2020-05-19 13:44 ` [PATCH 05/20] maccess: update the top of file comment Christoph Hellwig
2020-05-19 13:44 ` [PATCH 06/20] maccess: rename strncpy_from_unsafe_user to strncpy_from_user_nofault Christoph Hellwig
2020-05-19 13:44 ` [PATCH 07/20] maccess: rename strncpy_from_unsafe_strict to strncpy_from_kernel_nofault Christoph Hellwig
2020-05-19 13:44 ` [PATCH 08/20] maccess: rename strnlen_unsafe_user to strnlen_user_nofault Christoph Hellwig
2020-05-19 13:44 ` [PATCH 09/20] maccess: remove probe_read_common and probe_write_common Christoph Hellwig
2020-05-19 13:44 ` [PATCH 10/20] maccess: unify the probe kernel arch hooks Christoph Hellwig
2020-05-19 13:44 ` [PATCH 11/20] bpf: factor out a bpf_trace_copy_string helper Christoph Hellwig
2020-05-19 16:07   ` Linus Torvalds
2020-05-19 16:14     ` Christoph Hellwig
2020-05-19 16:36       ` Linus Torvalds
2020-05-19 13:44 ` [PATCH 12/20] maccess: remove strncpy_from_unsafe Christoph Hellwig
2020-05-19 16:25   ` Linus Torvalds
2020-05-19 16:41     ` Christoph Hellwig
2020-05-19 16:46       ` Linus Torvalds
2020-05-19 13:44 ` [PATCH 13/20] maccess: always use strict semantics for probe_kernel_read Christoph Hellwig
2020-05-19 16:33   ` Linus Torvalds
2020-05-20 11:11   ` Masami Hiramatsu
2020-05-20 11:13     ` Christoph Hellwig
2020-05-19 13:44 ` [PATCH 14/20] maccess: move user access routines together Christoph Hellwig
2020-05-19 13:44 ` [PATCH 15/20] maccess: allow architectures to provide kernel probing directly Christoph Hellwig
2020-05-19 13:44 ` [PATCH 16/20] x86: use non-set_fs based maccess routines Christoph Hellwig
2020-05-19 13:44 ` [PATCH 17/20] maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault Christoph Hellwig
2020-05-19 13:44 ` [PATCH 18/20] maccess: rename probe_user_{read,write} to copy_{from,to}_user_nofault Christoph Hellwig
2020-05-19 13:44 ` [PATCH 19/20] maccess: rename probe_kernel_address to get_kernel_nofault Christoph Hellwig
2020-05-19 13:44 ` [PATCH 20/20] maccess: return -ERANGE when copy_from_kernel_nofault_allowed fails Christoph Hellwig
2020-05-20 11:02   ` Masami Hiramatsu
2020-05-20 16:16     ` Christoph Hellwig
2020-05-19 16:34 ` clean up and streamline probe_kernel_* and friends v3 Linus Torvalds

Linux-parisc archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-parisc/0 linux-parisc/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-parisc linux-parisc/ https://lore.kernel.org/linux-parisc \
		linux-parisc@vger.kernel.org
	public-inbox-index linux-parisc

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-parisc


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git