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/*
* SPDX-License-Identifier: ISC
*
* Copyright (c) 2008 Otto Moerbeek <otto@drijf.net>
* Copyright (c) 2022 Todd C. Miller <Todd.Miller@sudo.ws>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/*
* This is an open source non-commercial project. Dear PVS-Studio, please check it.
* PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
*/
#include <config.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <errno.h>
#include <limits.h>
#include <string.h>
#if defined(HAVE_STDINT_H)
# include <stdint.h>
#elif defined(HAVE_INTTYPES_H)
# include <inttypes.h>
#endif
#include "sudo_compat.h"
#include "sudo_util.h"
#if !defined(MAP_ANON) && defined(MAP_ANONYMOUS)
# define MAP_ANON MAP_ANONYMOUS
#endif
#ifndef MAP_FAILED
# define MAP_FAILED ((void *)-1)
#endif
/*
* This is sqrt(SIZE_MAX+1), as s1*s2 <= SIZE_MAX
* if both s1 < MUL_NO_OVERFLOW and s2 < MUL_NO_OVERFLOW
*/
#define MUL_NO_OVERFLOW ((size_t)1 << (sizeof(size_t) * 4))
/*
* Allocate "size" bytes via mmap().
* Space is allocated to store the size for later unmapping.
*/
void *
sudo_mmap_alloc_v1(size_t size)
{
void *ptr;
unsigned long *ulp;
#ifndef MAP_ANON
int fd;
/* SunOS-style mmap allocation using /dev/zero. */
if ((fd = open("/dev/zero", O_RDWR)) == -1)
return NULL;
size += sizeof(unsigned long);
ptr = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
close(fd);
#else
size += sizeof(unsigned long);
ptr = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0);
#endif
if (ptr == MAP_FAILED) {
errno = ENOMEM;
return NULL;
}
/* Store size before the actual data. */
ulp = (unsigned long *)ptr;
ulp[0] = size;
return (void *)&ulp[1];
}
/*
* Allocate "nmemb" elements of "size" bytes via mmap().
* If overflow would occur, errno is set to ENOMEM and
* NULL is returned.
*/
void *
sudo_mmap_allocarray_v1(size_t nmemb, size_t size)
{
if ((nmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
nmemb > 0 && SIZE_MAX / nmemb < size) {
errno = ENOMEM;
return NULL;
}
return sudo_mmap_alloc_v1(nmemb * size);
}
/*
* Make a copy of "str" via mmap() and return it.
*/
char *
sudo_mmap_strdup_v1(const char *str)
{
size_t len = strlen(str);
char *newstr;
if (len == SIZE_MAX) {
errno = ENOMEM;
return NULL;
}
newstr = sudo_mmap_alloc_v1(len + 1);
if (newstr != NULL) {
memcpy(newstr, str, len);
newstr[len] = '\0';
}
return newstr;
}
/*
* Set the page permissions for the allocation represented by "ptr" to
* read-only. Returns 0 on success, -1 on failure.
*/
int
sudo_mmap_protect_v1(void *ptr)
{
if (ptr != NULL) {
unsigned long *ulp = ptr;
const unsigned long size = ulp[-1];
return mprotect((void *)&ulp[-1], size, PROT_READ);
}
/* Can't protect NULL. */
errno = EINVAL;
return -1;
}
/*
* Free "ptr" allocated by sudo_mmap_alloc().
* The allocated size is stored (as unsigned long) in ptr[-1].
*/
void
sudo_mmap_free_v1(void *ptr)
{
if (ptr != NULL) {
unsigned long *ulp = (unsigned long *)ptr - 1;
const unsigned long size = ulp[0];
int saved_errno = errno;
(void)munmap((void *)ulp, size);
errno = saved_errno;
}
}
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