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-rw-r--r--src/signal.c184
1 files changed, 184 insertions, 0 deletions
diff --git a/src/signal.c b/src/signal.c
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index 0000000..7f90d70
--- /dev/null
+++ b/src/signal.c
@@ -0,0 +1,184 @@
+/*
+ * 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;
+ 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);
+}