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Diffstat (limited to '')
| -rw-r--r-- | lib/util/closefrom.c | 183 |
1 files changed, 183 insertions, 0 deletions
diff --git a/lib/util/closefrom.c b/lib/util/closefrom.c new file mode 100644 index 0000000..64e9826 --- /dev/null +++ b/lib/util/closefrom.c @@ -0,0 +1,183 @@ +/* + * 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(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 = 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 */ |