mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-23 20:53:53 +08:00
967747bbc0
There are no remaining callers of set_fs(), so CONFIG_SET_FS can be removed globally, along with the thread_info field and any references to it. This turns access_ok() into a cheaper check against TASK_SIZE_MAX. As CONFIG_SET_FS is now gone, drop all remaining references to set_fs()/get_fs(), mm_segment_t, user_addr_max() and uaccess_kernel(). Acked-by: Sam Ravnborg <sam@ravnborg.org> # for sparc32 changes Acked-by: "Eric W. Biederman" <ebiederm@xmission.com> Tested-by: Sergey Matyukevich <sergey.matyukevich@synopsys.com> # for arc changes Acked-by: Stafford Horne <shorne@gmail.com> # [openrisc, asm-generic] Acked-by: Dinh Nguyen <dinguyen@kernel.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
121 lines
3.3 KiB
C
121 lines
3.3 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
#include <linux/kernel.h>
|
|
#include <linux/export.h>
|
|
#include <linux/uaccess.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/bitops.h>
|
|
|
|
#include <asm/word-at-a-time.h>
|
|
|
|
/*
|
|
* Do a strnlen, return length of string *with* final '\0'.
|
|
* 'count' is the user-supplied count, while 'max' is the
|
|
* address space maximum.
|
|
*
|
|
* Return 0 for exceptions (which includes hitting the address
|
|
* space maximum), or 'count+1' if hitting the user-supplied
|
|
* maximum count.
|
|
*
|
|
* NOTE! We can sometimes overshoot the user-supplied maximum
|
|
* if it fits in a aligned 'long'. The caller needs to check
|
|
* the return value against "> max".
|
|
*/
|
|
static inline long do_strnlen_user(const char __user *src, unsigned long count, unsigned long max)
|
|
{
|
|
const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
|
|
unsigned long align, res = 0;
|
|
unsigned long c;
|
|
|
|
/*
|
|
* Do everything aligned. But that means that we
|
|
* need to also expand the maximum..
|
|
*/
|
|
align = (sizeof(unsigned long) - 1) & (unsigned long)src;
|
|
src -= align;
|
|
max += align;
|
|
|
|
unsafe_get_user(c, (unsigned long __user *)src, efault);
|
|
c |= aligned_byte_mask(align);
|
|
|
|
for (;;) {
|
|
unsigned long data;
|
|
if (has_zero(c, &data, &constants)) {
|
|
data = prep_zero_mask(c, data, &constants);
|
|
data = create_zero_mask(data);
|
|
return res + find_zero(data) + 1 - align;
|
|
}
|
|
res += sizeof(unsigned long);
|
|
/* We already handled 'unsigned long' bytes. Did we do it all ? */
|
|
if (unlikely(max <= sizeof(unsigned long)))
|
|
break;
|
|
max -= sizeof(unsigned long);
|
|
unsafe_get_user(c, (unsigned long __user *)(src+res), efault);
|
|
}
|
|
res -= align;
|
|
|
|
/*
|
|
* Uhhuh. We hit 'max'. But was that the user-specified maximum
|
|
* too? If so, return the marker for "too long".
|
|
*/
|
|
if (res >= count)
|
|
return count+1;
|
|
|
|
/*
|
|
* Nope: we hit the address space limit, and we still had more
|
|
* characters the caller would have wanted. That's 0.
|
|
*/
|
|
efault:
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* strnlen_user: - Get the size of a user string INCLUDING final NUL.
|
|
* @str: The string to measure.
|
|
* @count: Maximum count (including NUL character)
|
|
*
|
|
* Context: User context only. This function may sleep if pagefaults are
|
|
* enabled.
|
|
*
|
|
* Get the size of a NUL-terminated string in user space.
|
|
*
|
|
* Returns the size of the string INCLUDING the terminating NUL.
|
|
* If the string is too long, returns a number larger than @count. User
|
|
* has to check the return value against "> count".
|
|
* On exception (or invalid count), returns 0.
|
|
*
|
|
* NOTE! You should basically never use this function. There is
|
|
* almost never any valid case for using the length of a user space
|
|
* string, since the string can be changed at any time by other
|
|
* threads. Use "strncpy_from_user()" instead to get a stable copy
|
|
* of the string.
|
|
*/
|
|
long strnlen_user(const char __user *str, long count)
|
|
{
|
|
unsigned long max_addr, src_addr;
|
|
|
|
if (unlikely(count <= 0))
|
|
return 0;
|
|
|
|
max_addr = TASK_SIZE_MAX;
|
|
src_addr = (unsigned long)untagged_addr(str);
|
|
if (likely(src_addr < max_addr)) {
|
|
unsigned long max = max_addr - src_addr;
|
|
long retval;
|
|
|
|
/*
|
|
* Truncate 'max' to the user-specified limit, so that
|
|
* we only have one limit we need to check in the loop
|
|
*/
|
|
if (max > count)
|
|
max = count;
|
|
|
|
if (user_read_access_begin(str, max)) {
|
|
retval = do_strnlen_user(str, count, max);
|
|
user_read_access_end();
|
|
return retval;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(strnlen_user);
|