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/*
* SPDX-License-Identifier: ISC
*
* Copyright (c) 2013-2015 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 <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <sudo.h>
/*
* Add an fd to preserve.
*/
int
add_preserved_fd(struct preserved_fd_list *pfds, int fd)
{
struct preserved_fd *pfd, *pfd_new;
debug_decl(add_preserved_fd, SUDO_DEBUG_UTIL);
pfd_new = malloc(sizeof(*pfd));
if (pfd_new == NULL)
sudo_fatalx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
pfd_new->lowfd = fd;
pfd_new->highfd = fd;
pfd_new->flags = fcntl(fd, F_GETFD);
if (pfd_new->flags == -1) {
free(pfd_new);
debug_return_int(-1);
}
TAILQ_FOREACH(pfd, pfds, entries) {
if (fd == pfd->highfd) {
/* already preserved */
sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO,
"fd %d already preserved", fd);
free(pfd_new);
pfd_new = NULL;
break;
}
if (fd < pfd->highfd) {
TAILQ_INSERT_BEFORE(pfd, pfd_new, entries);
sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO,
"preserving fd %d", fd);
pfd_new = NULL;
break;
}
}
if (pfd_new != NULL) {
TAILQ_INSERT_TAIL(pfds, pfd_new, entries);
sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO,
"preserving fd %d", fd);
}
debug_return_int(0);
}
/*
* Close all descriptors, startfd and higher except those listed
* in pfds.
*/
void
closefrom_except(int startfd, struct preserved_fd_list *pfds)
{
int fd, lastfd = -1;
struct preserved_fd *pfd, *pfd_next;
unsigned char *fdbits;
debug_decl(closefrom_except, SUDO_DEBUG_UTIL);
/* First, relocate preserved fds to be as contiguous as possible. */
TAILQ_FOREACH_REVERSE_SAFE(pfd, pfds, preserved_fd_list, entries, pfd_next) {
if (pfd->highfd < startfd)
continue;
fd = dup(pfd->highfd);
if (fd == -1) {
sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO|SUDO_DEBUG_ERRNO,
"dup %d", pfd->highfd);
if (errno == EBADF) {
TAILQ_REMOVE(pfds, pfd, entries);
continue;
}
/* NOTE: still need to adjust lastfd below with unchanged lowfd. */
} else if (fd < pfd->highfd) {
sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO,
"dup %d -> %d", pfd->highfd, pfd->lowfd);
sudo_debug_update_fd(pfd->highfd, pfd->lowfd);
pfd->lowfd = fd;
fd = pfd->highfd;
}
if (fd != -1)
(void) close(fd);
if (pfd->lowfd > lastfd)
lastfd = pfd->lowfd; /* highest (relocated) preserved fd */
}
if (lastfd == -1) {
/* No fds to preserve. */
sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO,
"closefrom(%d)", startfd);
closefrom(startfd);
debug_return;
}
/* Create bitmap of preserved (relocated) fds. */
fdbits = calloc((size_t)(lastfd + NBBY) / NBBY, 1);
if (fdbits == NULL)
sudo_fatalx(U_("%s: %s"), __func__, U_("unable to allocate memory"));
TAILQ_FOREACH(pfd, pfds, entries) {
sudo_setbit(fdbits, pfd->lowfd);
}
/*
* Close any unpreserved fds [startfd,lastfd]
*/
for (fd = startfd; fd <= lastfd; fd++) {
if (!sudo_isset(fdbits, fd)) {
sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO,
"closing fd %d", fd);
#ifdef __APPLE__
/* Avoid potential libdispatch crash when we close its fds. */
(void) fcntl(fd, F_SETFD, FD_CLOEXEC);
#else
(void) close(fd);
#endif
}
}
free(fdbits);
/* Let closefrom() do the rest for us. */
if (lastfd + 1 > startfd)
startfd = lastfd + 1;
sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO,
"closefrom(%d)", startfd);
closefrom(startfd);
/* Restore preserved fds and set flags. */
TAILQ_FOREACH_REVERSE(pfd, pfds, preserved_fd_list, entries) {
if (pfd->lowfd != pfd->highfd) {
if (dup2(pfd->lowfd, pfd->highfd) == -1) {
sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,
"dup2(%d, %d): %s", pfd->lowfd, pfd->highfd,
strerror(errno));
} else {
sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO,
"dup2(%d, %d)", pfd->lowfd, pfd->highfd);
}
if (fcntl(pfd->highfd, F_SETFD, pfd->flags) == -1) {
sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,
"fcntl(%d, F_SETFD, %d): %s", pfd->highfd,
pfd->flags, strerror(errno));
} else {
sudo_debug_printf(SUDO_DEBUG_DEBUG|SUDO_DEBUG_LINENO,
"fcntl(%d, F_SETFD, %d)", pfd->highfd, pfd->flags);
}
sudo_debug_update_fd(pfd->lowfd, pfd->highfd);
(void) close(pfd->lowfd);
pfd->lowfd = pfd->highfd;
}
}
debug_return;
}
/*
* Parse a comma-separated list of fds and add them to preserved_fds.
*/
void
parse_preserved_fds(struct preserved_fd_list *pfds, const char *fdstr)
{
const char *cp = fdstr;
long lval;
char *ep;
debug_decl(parse_preserved_fds, SUDO_DEBUG_UTIL);
do {
errno = 0;
lval = strtol(cp, &ep, 10);
if (ep == cp || (*ep != ',' && *ep != '\0')) {
sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,
"unable to parse fd string %s", cp);
break;
}
if ((errno == ERANGE && lval == LONG_MAX) || lval < 0 || lval > INT_MAX) {
sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_LINENO,
"range error parsing fd string %s", cp);
} else {
add_preserved_fd(pfds, (int)lval);
}
cp = ep + 1;
} while (*ep != '\0');
debug_return;
}
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