/usr/share/systemtap/runtime/linux/copy.c is in systemtap-common 3.1-3ubuntu0.1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 | /* -*- linux-c -*-
* Copy from user space functions
* Copyright (C) 2005-2017 Red Hat Inc.
* Copyright (C) 2005 Intel Corporation.
*
* This file is part of systemtap, and is free software. You can
* redistribute it and/or modify it under the terms of the GNU General
* Public License (GPL); either version 2, or (at your option) any
* later version.
*/
#ifndef _STAPLINUX_COPY_C_ /* -*- linux-c -*- */
#define _STAPLINUX_COPY_C_
/** @file copy.c
* @brief Functions to copy from user space.
*/
/** @addtogroup copy Functions to copy from user space.
* Functions to copy from user space.
* None of these functions will sleep (for example to allow pages
* to be swapped in). It is possible (although rare) that the data
* in user space will not present and these functions will return an error.
* @{
*/
/** Copy a NULL-terminated string from userspace.
* On success, returns the length of the string (not including the trailing
* NULL).
*
* If access to userspace fails, returns -EFAULT (some data may have been
* copied).
* @param dst Destination address, in kernel space. This buffer must be at
* least <i>count</i> bytes long.
* @param src Source address, in user space.
* @param count Maximum number of bytes to copy, including the trailing NULL.
*
* If <i>count</i> is smaller than the length of the string, copies
* <i>count</i> bytes and returns <i>count</i>.
*/
/* XXX: see also kread/uread in loc2c-runtime.h */
static long _stp_strncpy_from_user(char *dst, const char __user *src, long count)
{
long res = -EFAULT;
mm_segment_t _oldfs = get_fs();
set_fs(USER_DS);
pagefault_disable();
/* XXX: The following preempt() manipulations should be
redundant with probe entry/exit code, but for unknown
reasons on RHEL5/6 conversions.exp intermittently fails
without this. */
preempt_disable();
if (!lookup_bad_addr(VERIFY_READ, (const unsigned long)src, count))
res = strncpy_from_user(dst, src, count);
preempt_enable_no_resched();
pagefault_enable();
set_fs(_oldfs);
return res;
}
/** Copy a block of data from user space.
*
* If data could not be copied, this function will not modify the
* destination.
*
* @param dst Destination address, in kernel space.
* @param src Source address, in user space.
* @param count Number of bytes to copy.
* @return number of bytes that could not be copied. On success,
* this will be zero.
*
*/
/* XXX: see also kread/uread in loc2c-runtime.h */
static unsigned long _stp_copy_from_user(char *dst, const char __user *src, unsigned long count)
{
if (count) {
mm_segment_t _oldfs = get_fs();
set_fs(USER_DS);
pagefault_disable();
if (!lookup_bad_addr(VERIFY_READ, (const unsigned long)src, count))
count = __copy_from_user_inatomic(dst, src, count);
else
/* Notice that if we fail, we don't modify
* the destination. In the failure case, we
* can't trust 'count' to be reasonable. */
count = -EFAULT;
pagefault_enable();
set_fs(_oldfs);
}
return count;
}
/** @} */
#endif /* _STAPLINUX_COPY_C_ */
|