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/*
* SPDX-License-Identifier: ISC
*
* Copyright (c) 2004-2005, 2007, 2010, 2012-2015, 2017-2022
* 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>
#ifndef HAVE_CLOSEFROM
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdlib.h>
#include <unistd.h>
#ifdef HAVE_PSTAT_GETPROC
# include <sys/pstat.h>
#else
# include <dirent.h>
#endif
#ifdef HAVE_LIBPROC_H
# include <libproc.h>
#endif
#ifdef HAVE_LINUX_CLOSE_RANGE_H
# include <linux/close_range.h>
#endif
#include <sudo_compat.h>
#include <sudo_util.h>
#include <pathnames.h>
#ifndef OPEN_MAX
# define OPEN_MAX 256
#endif
/* Avoid potential libdispatch crash on macOS when we close its fds. */
#ifdef __APPLE__
# define closefrom_close(x) fcntl((x), F_SETFD, FD_CLOEXEC)
#else
# define closefrom_close(x) close(x)
#endif
/*
* Close all file descriptors greater than or equal to lowfd.
* This is the expensive (fallback) method.
*/
static void
closefrom_fallback(int lowfd)
{
long fd, maxfd;
/*
* Fall back on sysconf(_SC_OPEN_MAX). This is equivalent to
* checking the RLIMIT_NOFILE soft limit. It is possible for
* there to be open file descriptors past this limit but there's
* not much we can do about that since the hard limit may be
* RLIM_INFINITY (LLONG_MAX or ULLONG_MAX on modern systems).
*/
maxfd = sysconf(_SC_OPEN_MAX);
if (maxfd < OPEN_MAX)
maxfd = OPEN_MAX;
/* Make sure we didn't get RLIM_INFINITY as the upper limit. */
if (maxfd > INT_MAX)
maxfd = INT_MAX;
for (fd = lowfd; fd < maxfd; fd++) {
(void)closefrom_close((int)fd);
}
}
/*
* Close all file descriptors greater than or equal to lowfd.
* We try the fast way first, falling back on the slow method.
*/
void
sudo_closefrom(int lowfd)
{
#if defined(HAVE_PSTAT_GETPROC)
struct pst_status pst;
#elif defined(HAVE_DIRFD)
const char *path;
DIR *dirp;
#endif
#if defined(HAVE_PROC_PIDINFO)
struct proc_fdinfo *buf = NULL;
const pid_t pid = getpid();
int i, n, len;
#endif
/* Try the fast method first, if possible. */
#if defined(HAVE_FCNTL_CLOSEM)
if (fcntl(lowfd, F_CLOSEM, 0) != -1)
return;
#elif defined(HAVE_CLOSE_RANGE)
if (close_range((unsigned int)lowfd, ~0U, 0) != -1)
return;
#elif defined(HAVE_PROC_PIDINFO)
len = proc_pidinfo(pid, PROC_PIDLISTFDS, 0, NULL, 0);
switch (len) {
case 0:
/* No open files. */
return;
case -1:
/* Fall back on other methods. */
break;
default:
/* Allocate space for 4 extra fds to leave some wiggle room. */
buf = malloc(len + (PROC_PIDLISTFD_SIZE * 4));
if (buf == NULL)
break;
n = proc_pidinfo(pid, PROC_PIDLISTFDS, 0, buf, len);
if (n == -1 || n > len) {
free(buf);
break;
}
n /= PROC_PIDLISTFD_SIZE;
for (i = 0; i < n; i++) {
if (buf[i].proc_fd >= lowfd) {
(void)closefrom_close(buf[i].proc_fd);
}
}
free(buf);
return;
}
#endif /* HAVE_PROC_PIDINFO */
#if defined(HAVE_PSTAT_GETPROC)
/*
* EOVERFLOW is not a fatal error for the fields we use.
* See the "EOVERFLOW Error" section of pstat_getvminfo(3).
*/
if (pstat_getproc(&pst, sizeof(pst), 0, getpid()) != -1 ||
errno == EOVERFLOW) {
int fd;
for (fd = lowfd; fd <= pst.pst_highestfd; fd++)
(void)closefrom_close(fd);
return;
}
#elif defined(HAVE_DIRFD)
/* Use /proc/self/fd (or /dev/fd on macOS) if it exists. */
# ifdef __APPLE__
path = _PATH_DEV "fd";
# else
path = "/proc/self/fd";
# endif
if ((dirp = opendir(path)) != NULL) {
struct dirent *dent;
while ((dent = readdir(dirp)) != NULL) {
const char *errstr;
int fd = (int)sudo_strtonum(dent->d_name, lowfd, INT_MAX, &errstr);
if (errstr == NULL && fd != dirfd(dirp)) {
(void)closefrom_close(fd);
}
}
(void)closedir(dirp);
return;
}
#endif /* HAVE_DIRFD */
/* Do things the slow way. */
closefrom_fallback(lowfd);
}
#endif /* HAVE_CLOSEFROM */
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