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/*
* SPDX-License-Identifier: ISC
*
* Copyright (c) 2009-2021 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/stat.h>
#include <stdio.h>
#include <stdlib.h>
#ifdef HAVE_STDBOOL_H
# include <stdbool.h>
#else
# include "compat/stdbool.h"
#endif
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include "sudo_compat.h"
#include "sudo_debug.h"
#include "sudo_fatal.h"
#include "sudo_gettext.h"
#include "sudo_iolog.h"
#include "sudo_util.h"
/*
* Read the on-disk sequence number, set sessid to the next
* number, and update the on-disk copy.
* Uses file locking to avoid sequence number collisions.
*/
bool
iolog_nextid(const char *iolog_dir, char sessid[7])
{
char buf[32], *ep;
int i, fd = -1;
unsigned long id = 0;
size_t len;
ssize_t nread;
bool ret = false;
char pathbuf[PATH_MAX];
static const char b36char[] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
const uid_t iolog_uid = iolog_get_uid();
const gid_t iolog_gid = iolog_get_gid();
debug_decl(iolog_nextid, SUDO_DEBUG_UTIL);
/*
* Create I/O log directory if it doesn't already exist.
*/
len = strlcpy(pathbuf, iolog_dir, sizeof(pathbuf));
if (len >= sizeof(pathbuf)) {
errno = ENAMETOOLONG;
sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,
"%s: %s", __func__, iolog_dir);
goto done;
}
if (!iolog_mkdirs(pathbuf))
goto done;
/*
* Open sequence file
*/
len = strlcat(pathbuf, "/seq", sizeof(pathbuf));
if (len >= sizeof(pathbuf)) {
errno = ENAMETOOLONG;
sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,
"%s: %s/seq", __func__, iolog_dir);
goto done;
}
fd = iolog_openat(AT_FDCWD, pathbuf, O_RDWR|O_CREAT);
if (fd == -1) {
sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,
"%s: unable to open %s", __func__, pathbuf);
goto done;
}
if (!sudo_lock_file(fd, SUDO_LOCK)) {
sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,
"unable to lock %s", pathbuf);
goto done;
}
if (fchown(fd, iolog_uid, iolog_gid) != 0) {
sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,
"%s: unable to fchown %d:%d %s", __func__,
(int)iolog_uid, (int)iolog_gid, pathbuf);
}
/* Read current seq number (base 36). */
nread = read(fd, buf, sizeof(buf) - 1);
if (nread != 0) {
if (nread == -1) {
goto done;
}
if (buf[nread - 1] == '\n')
nread--;
buf[nread] = '\0';
id = strtoul(buf, &ep, 36);
if (ep == buf || *ep != '\0' || id >= iolog_get_maxseq()) {
sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,
"%s: bad sequence number: %s", pathbuf, buf);
id = 0;
}
}
id++;
/*
* Convert id to a string and stash in sessid.
* Note that that least significant digits go at the end of the string.
*/
for (i = 5; i >= 0; i--) {
buf[i] = b36char[id % 36];
id /= 36;
}
buf[6] = '\n';
/* Stash id for logging purposes. */
memcpy(sessid, buf, 6);
sessid[6] = '\0';
/* Rewind and overwrite old seq file, including the NUL byte. */
if (pwrite(fd, buf, 7, 0) != 7) {
sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,
"%s: unable to write %s", __func__, pathbuf);
goto done;
}
ret = true;
done:
if (fd != -1)
close(fd);
debug_return_bool(ret);
}
|
