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/*
* SPDX-License-Identifier: ISC
*
* Copyright (c) 2009-2016 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 <string.h>
#include <errno.h>
#include <signal.h>
#include "sudo.h"
#include "sudo_exec.h"
static struct signal_state {
int signo;
int restore;
struct sigaction sa;
} saved_signals[] = {
{ SIGALRM }, /* SAVED_SIGALRM */
{ SIGCHLD }, /* SAVED_SIGCHLD */
{ SIGCONT }, /* SAVED_SIGCONT */
{ SIGHUP }, /* SAVED_SIGHUP */
{ SIGINT }, /* SAVED_SIGINT */
{ SIGPIPE }, /* SAVED_SIGPIPE */
{ SIGQUIT }, /* SAVED_SIGQUIT */
{ SIGTERM }, /* SAVED_SIGTERM */
{ SIGTSTP }, /* SAVED_SIGTSTP */
{ SIGTTIN }, /* SAVED_SIGTTIN */
{ SIGTTOU }, /* SAVED_SIGTTOU */
{ SIGUSR1 }, /* SAVED_SIGUSR1 */
{ SIGUSR2 }, /* SAVED_SIGUSR2 */
{ -1 }
};
static sig_atomic_t pending_signals[NSIG];
static void
sudo_handler(int signo)
{
/* Mark signal as pending. */
pending_signals[signo] = 1;
}
bool
signal_pending(int signo)
{
return pending_signals[signo] == 1;
}
/*
* Save signal handler state so it can be restored before exec.
*/
void
save_signals(void)
{
struct signal_state *ss;
debug_decl(save_signals, SUDO_DEBUG_MAIN);
for (ss = saved_signals; ss->signo != -1; ss++) {
if (sigaction(ss->signo, NULL, &ss->sa) != 0)
sudo_warn(U_("unable to save handler for signal %d"), ss->signo);
}
debug_return;
}
/*
* Restore signal handlers to initial state for exec.
*/
void
restore_signals(void)
{
struct signal_state *ss;
debug_decl(restore_signals, SUDO_DEBUG_MAIN);
for (ss = saved_signals; ss->signo != -1; ss++) {
if (ss->restore) {
sudo_debug_printf(SUDO_DEBUG_INFO,
"restoring handler for signal %d: %s", ss->signo,
ss->sa.sa_handler == SIG_IGN ? "SIG_IGN" :
ss->sa.sa_handler == SIG_DFL ? "SIG_DFL" : "???");
if (sigaction(ss->signo, &ss->sa, NULL) != 0) {
sudo_warn(U_("unable to restore handler for signal %d"),
ss->signo);
}
}
}
debug_return;
}
/*
* Trap tty-generated (and other) signals so we can't be killed before
* calling the policy close function. The signal pipe will be drained
* in sudo_execute() before running the command and new handlers will
* be installed in the parent.
*/
void
init_signals(void)
{
struct sigaction sa;
struct signal_state *ss;
debug_decl(init_signals, SUDO_DEBUG_MAIN);
memset(&sa, 0, sizeof(sa));
sigfillset(&sa.sa_mask);
sa.sa_flags = SA_RESTART;
sa.sa_handler = sudo_handler;
for (ss = saved_signals; ss->signo > 0; ss++) {
switch (ss->signo) {
case SIGCONT:
case SIGPIPE:
case SIGTTIN:
case SIGTTOU:
/* Don't install these until exec time. */
break;
case SIGCHLD:
/* Sudo needs to be able to catch SIGCHLD. */
if (ss->sa.sa_handler == SIG_IGN) {
sudo_debug_printf(SUDO_DEBUG_INFO,
"will restore signal %d on exec", SIGCHLD);
ss->restore = true;
}
if (sigaction(SIGCHLD, &sa, NULL) != 0) {
sudo_warn(U_("unable to set handler for signal %d"),
SIGCHLD);
}
break;
default:
if (ss->sa.sa_handler != SIG_IGN) {
if (sigaction(ss->signo, &sa, NULL) != 0) {
sudo_warn(U_("unable to set handler for signal %d"),
ss->signo);
}
}
break;
}
}
/* Ignore SIGPIPE until exec. */
if (saved_signals[SAVED_SIGPIPE].sa.sa_handler != SIG_IGN) {
sudo_debug_printf(SUDO_DEBUG_INFO,
"will restore signal %d on exec", SIGPIPE);
saved_signals[SAVED_SIGPIPE].restore = true;
sa.sa_handler = SIG_IGN;
if (sigaction(SIGPIPE, &sa, NULL) != 0)
sudo_warn(U_("unable to set handler for signal %d"), SIGPIPE);
}
debug_return;
}
/*
* Like sigaction() but sets restore flag in saved_signals[]
* if needed.
*/
int
sudo_sigaction(int signo, struct sigaction *sa, struct sigaction *osa)
{
struct signal_state *ss;
int ret;
debug_decl(sudo_sigaction, SUDO_DEBUG_MAIN);
for (ss = saved_signals; ss->signo > 0; ss++) {
if (ss->signo == signo) {
/* If signal was or now is ignored, restore old handler on exec. */
if (ss->sa.sa_handler == SIG_IGN || sa->sa_handler == SIG_IGN) {
sudo_debug_printf(SUDO_DEBUG_INFO,
"will restore signal %d on exec", signo);
ss->restore = true;
}
break;
}
}
ret = sigaction(signo, sa, osa);
debug_return_int(ret);
}
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