Release 4.11 mm/maccess.c
/*
* Access kernel memory without faulting.
*/
#include <linux/export.h>
#include <linux/mm.h>
#include <linux/uaccess.h>
/**
* 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.
*
* 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.
*/
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)
{
long ret;
mm_segment_t old_fs = get_fs();
set_fs(KERNEL_DS);
pagefault_disable();
ret = __copy_from_user_inatomic(dst,
(__force const void __user *)src, size);
pagefault_enable();
set_fs(old_fs);
return ret ? -EFAULT : 0;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Ingo Molnar | 37 | 54.41% | 1 | 25.00% |
| Jason Wessel | 30 | 44.12% | 2 | 50.00% |
| Steven Rostedt | 1 | 1.47% | 1 | 25.00% |
| Total | 68 | 100.00% | 4 | 100.00% |
EXPORT_SYMBOL_GPL(probe_kernel_read);
/**
* 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.
*/
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 ret;
mm_segment_t old_fs = get_fs();
set_fs(KERNEL_DS);
pagefault_disable();
ret = __copy_to_user_inatomic((__force void __user *)dst, src, size);
pagefault_enable();
set_fs(old_fs);
return ret ? -EFAULT : 0;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Ingo Molnar | 36 | 53.73% | 1 | 25.00% |
| Jason Wessel | 30 | 44.78% | 2 | 50.00% |
| Steven Rostedt | 1 | 1.49% | 1 | 25.00% |
| Total | 67 | 100.00% | 4 | 100.00% |
EXPORT_SYMBOL_GPL(probe_kernel_write);
/**
* 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.
* @src: 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 strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count)
{
mm_segment_t old_fs = get_fs();
const void *src = unsafe_addr;
long ret;
if (unlikely(count <= 0))
return 0;
set_fs(KERNEL_DS);
pagefault_disable();
do {
ret = __get_user(*dst++, (const char __user __force *)src++);
} while (dst[-1] && ret == 0 && src - unsafe_addr < count);
dst[-1] = '\0';
pagefault_enable();
set_fs(old_fs);
return ret ? -EFAULT : src - unsafe_addr;
}
Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Alexei Starovoitov | 115 | 95.83% | 1 | 33.33% |
| Linus Torvalds | 3 | 2.50% | 1 | 33.33% |
| Rasmus Villemoes | 2 | 1.67% | 1 | 33.33% |
| Total | 120 | 100.00% | 3 | 100.00% |
Overall Contributors
| Person | Tokens | Prop | Commits | CommitProp |
| Ingo Molnar | 119 | 36.73% | 1 | 9.09% |
| Alexei Starovoitov | 116 | 35.80% | 1 | 9.09% |
| Jason Wessel | 75 | 23.15% | 2 | 18.18% |
| Steven Rostedt | 4 | 1.23% | 1 | 9.09% |
| Linus Torvalds | 3 | 0.93% | 1 | 9.09% |
| David Howells | 2 | 0.62% | 1 | 9.09% |
| Rasmus Villemoes | 2 | 0.62% | 1 | 9.09% |
| Paul Gortmaker | 1 | 0.31% | 1 | 9.09% |
| Heiko Carstens | 1 | 0.31% | 1 | 9.09% |
| Andrew Morton | 1 | 0.31% | 1 | 9.09% |
| Total | 324 | 100.00% | 11 | 100.00% |
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