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BACKPORT: maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault

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Better describe what these functions do.

Suggested-by: Linus Torvalds <[email protected]>
Signed-off-by: Christoph Hellwig <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Change-Id: I7fc23cc8af03ab2582ea8779bc781124f30c95e7
This commit is contained in:
Christoph Hellwig 2020-06-17 09:37:53 +02:00 • committed by basamaryan
commit 1052e273f8
No known key found for this signature in database
GPG key ID: 210D5384FB2A5885
46 changed files with 134 additions and 121 deletions
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47
mm/maccess.c
View file

@ -6,14 +6,15 @@
#include <linux/mm.h>
#include <linux/uaccess.h>
bool __weak probe_kernel_read_allowed(const void *unsafe_src, size_t size)
bool __weak copy_from_kernel_nofault_allowed(const void *unsafe_src,
size_t size)
{
return true;
}
#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); \
@ -21,25 +22,25 @@ bool __weak probe_kernel_read_allowed(const void *unsafe_src, size_t size)
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(src, size))
if (!copy_from_kernel_nofault_allowed(src, size))
return -ERANGE;
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); \
@ -47,13 +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:
@ -67,7 +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(unsafe_addr, count))
if (!copy_from_kernel_nofault_allowed(unsafe_addr, count))
return -ERANGE;
pagefault_disable();
@ -87,7 +88,7 @@ Efault:
}
#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 +99,15 @@ 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
* 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(src, size))
if (!copy_from_kernel_nofault_allowed(src, size))
return -ERANGE;
set_fs(KERNEL_DS);
@ -120,7 +121,7 @@ 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_user_read(): safely attempt to read from a user-space location
@ -159,7 +160,7 @@ 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_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();
@ -230,7 +231,7 @@ long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count)
if (unlikely(count <= 0))
return 0;
if (!probe_kernel_read_allowed(unsafe_addr, count))
if (!copy_from_kernel_nofault_allowed(unsafe_addr, count))
return -ERANGE;
set_fs(KERNEL_DS);

2
mm/rodata_test.c
View file

@ -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;

2
mm/slub.c
View file

@ -303,7 +303,7 @@ 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);
}