![Jan Beulich](/assets/img/avatar_default.png)
Similarly to copy_from_user(), where the range check is to protect against kernel memory corruption, copy_to_user() can benefit from such checking too: Here it protects against kernel information leaks. Signed-off-by: Jan Beulich <jbeulich@suse.com> Cc: <arjan@linux.intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/5265059502000078000FC4F6@nat28.tlf.novell.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Arjan van de Ven <arjan@linux.intel.com>
188 lines
5.4 KiB
C
188 lines
5.4 KiB
C
#ifndef _ASM_X86_UACCESS_32_H
|
|
#define _ASM_X86_UACCESS_32_H
|
|
|
|
/*
|
|
* User space memory access functions
|
|
*/
|
|
#include <linux/errno.h>
|
|
#include <linux/thread_info.h>
|
|
#include <linux/string.h>
|
|
#include <asm/asm.h>
|
|
#include <asm/page.h>
|
|
|
|
unsigned long __must_check __copy_to_user_ll
|
|
(void __user *to, const void *from, unsigned long n);
|
|
unsigned long __must_check __copy_from_user_ll
|
|
(void *to, const void __user *from, unsigned long n);
|
|
unsigned long __must_check __copy_from_user_ll_nozero
|
|
(void *to, const void __user *from, unsigned long n);
|
|
unsigned long __must_check __copy_from_user_ll_nocache
|
|
(void *to, const void __user *from, unsigned long n);
|
|
unsigned long __must_check __copy_from_user_ll_nocache_nozero
|
|
(void *to, const void __user *from, unsigned long n);
|
|
|
|
/**
|
|
* __copy_to_user_inatomic: - Copy a block of data into user space, with less checking.
|
|
* @to: Destination address, in user space.
|
|
* @from: Source address, in kernel space.
|
|
* @n: Number of bytes to copy.
|
|
*
|
|
* Context: User context only.
|
|
*
|
|
* Copy data from kernel space to user space. Caller must check
|
|
* the specified block with access_ok() before calling this function.
|
|
* The caller should also make sure he pins the user space address
|
|
* so that we don't result in page fault and sleep.
|
|
*
|
|
* Here we special-case 1, 2 and 4-byte copy_*_user invocations. On a fault
|
|
* we return the initial request size (1, 2 or 4), as copy_*_user should do.
|
|
* If a store crosses a page boundary and gets a fault, the x86 will not write
|
|
* anything, so this is accurate.
|
|
*/
|
|
|
|
static __always_inline unsigned long __must_check
|
|
__copy_to_user_inatomic(void __user *to, const void *from, unsigned long n)
|
|
{
|
|
if (__builtin_constant_p(n)) {
|
|
unsigned long ret;
|
|
|
|
switch (n) {
|
|
case 1:
|
|
__put_user_size(*(u8 *)from, (u8 __user *)to,
|
|
1, ret, 1);
|
|
return ret;
|
|
case 2:
|
|
__put_user_size(*(u16 *)from, (u16 __user *)to,
|
|
2, ret, 2);
|
|
return ret;
|
|
case 4:
|
|
__put_user_size(*(u32 *)from, (u32 __user *)to,
|
|
4, ret, 4);
|
|
return ret;
|
|
}
|
|
}
|
|
return __copy_to_user_ll(to, from, n);
|
|
}
|
|
|
|
/**
|
|
* __copy_to_user: - Copy a block of data into user space, with less checking.
|
|
* @to: Destination address, in user space.
|
|
* @from: Source address, in kernel space.
|
|
* @n: Number of bytes to copy.
|
|
*
|
|
* Context: User context only. This function may sleep.
|
|
*
|
|
* Copy data from kernel space to user space. Caller must check
|
|
* the specified block with access_ok() before calling this function.
|
|
*
|
|
* Returns number of bytes that could not be copied.
|
|
* On success, this will be zero.
|
|
*/
|
|
static __always_inline unsigned long __must_check
|
|
__copy_to_user(void __user *to, const void *from, unsigned long n)
|
|
{
|
|
might_fault();
|
|
return __copy_to_user_inatomic(to, from, n);
|
|
}
|
|
|
|
static __always_inline unsigned long
|
|
__copy_from_user_inatomic(void *to, const void __user *from, unsigned long n)
|
|
{
|
|
/* Avoid zeroing the tail if the copy fails..
|
|
* If 'n' is constant and 1, 2, or 4, we do still zero on a failure,
|
|
* but as the zeroing behaviour is only significant when n is not
|
|
* constant, that shouldn't be a problem.
|
|
*/
|
|
if (__builtin_constant_p(n)) {
|
|
unsigned long ret;
|
|
|
|
switch (n) {
|
|
case 1:
|
|
__get_user_size(*(u8 *)to, from, 1, ret, 1);
|
|
return ret;
|
|
case 2:
|
|
__get_user_size(*(u16 *)to, from, 2, ret, 2);
|
|
return ret;
|
|
case 4:
|
|
__get_user_size(*(u32 *)to, from, 4, ret, 4);
|
|
return ret;
|
|
}
|
|
}
|
|
return __copy_from_user_ll_nozero(to, from, n);
|
|
}
|
|
|
|
/**
|
|
* __copy_from_user: - Copy a block of data from user space, with less checking.
|
|
* @to: Destination address, in kernel space.
|
|
* @from: Source address, in user space.
|
|
* @n: Number of bytes to copy.
|
|
*
|
|
* Context: User context only. This function may sleep.
|
|
*
|
|
* Copy data from user space to kernel space. Caller must check
|
|
* the specified block with access_ok() before calling this function.
|
|
*
|
|
* Returns number of bytes that could not be copied.
|
|
* On success, this will be zero.
|
|
*
|
|
* If some data could not be copied, this function will pad the copied
|
|
* data to the requested size using zero bytes.
|
|
*
|
|
* An alternate version - __copy_from_user_inatomic() - may be called from
|
|
* atomic context and will fail rather than sleep. In this case the
|
|
* uncopied bytes will *NOT* be padded with zeros. See fs/filemap.h
|
|
* for explanation of why this is needed.
|
|
*/
|
|
static __always_inline unsigned long
|
|
__copy_from_user(void *to, const void __user *from, unsigned long n)
|
|
{
|
|
might_fault();
|
|
if (__builtin_constant_p(n)) {
|
|
unsigned long ret;
|
|
|
|
switch (n) {
|
|
case 1:
|
|
__get_user_size(*(u8 *)to, from, 1, ret, 1);
|
|
return ret;
|
|
case 2:
|
|
__get_user_size(*(u16 *)to, from, 2, ret, 2);
|
|
return ret;
|
|
case 4:
|
|
__get_user_size(*(u32 *)to, from, 4, ret, 4);
|
|
return ret;
|
|
}
|
|
}
|
|
return __copy_from_user_ll(to, from, n);
|
|
}
|
|
|
|
static __always_inline unsigned long __copy_from_user_nocache(void *to,
|
|
const void __user *from, unsigned long n)
|
|
{
|
|
might_fault();
|
|
if (__builtin_constant_p(n)) {
|
|
unsigned long ret;
|
|
|
|
switch (n) {
|
|
case 1:
|
|
__get_user_size(*(u8 *)to, from, 1, ret, 1);
|
|
return ret;
|
|
case 2:
|
|
__get_user_size(*(u16 *)to, from, 2, ret, 2);
|
|
return ret;
|
|
case 4:
|
|
__get_user_size(*(u32 *)to, from, 4, ret, 4);
|
|
return ret;
|
|
}
|
|
}
|
|
return __copy_from_user_ll_nocache(to, from, n);
|
|
}
|
|
|
|
static __always_inline unsigned long
|
|
__copy_from_user_inatomic_nocache(void *to, const void __user *from,
|
|
unsigned long n)
|
|
{
|
|
return __copy_from_user_ll_nocache_nozero(to, from, n);
|
|
}
|
|
|
|
#endif /* _ASM_X86_UACCESS_32_H */
|