From c18468d1a55ba5f981c8061e0d32007afe304d08 Mon Sep 17 00:00:00 2001
From: "Todd C. Miller" <Todd.Miller@courtesan.com>
Date: Wed, 2 Feb 2011 12:44:35 -0500
Subject: [PATCH] Save signal state before changing handlers and restore before
 we execute the command.

---
 src/exec.c     | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 src/exec_pty.c | 19 ++-----------------
 src/sudo.h     |  2 ++
 3 files changed, 51 insertions(+), 17 deletions(-)

diff --git a/src/exec.c b/src/exec.c
index 5969ed7d3..f3038a331 100644
--- a/src/exec.c
+++ b/src/exec.c
@@ -128,6 +128,7 @@ static int fork_cmnd(struct command_details *details, char *argv[],
 	close(signal_pipe[0]);
 	close(signal_pipe[1]);
 	fcntl(sv[1], F_SETFD, FD_CLOEXEC);
+	restore_signals();
 	if (exec_setup(details, NULL, -1) == TRUE) {
 	    /* headed for execve() */
 	    if (details->closefrom >= 0)
@@ -147,6 +148,52 @@ static int fork_cmnd(struct command_details *details, char *argv[],
     return pid;
 }
 
+static struct signal_state {
+    int signo;
+    sigaction_t sa;
+} saved_signals[] = {
+    { SIGALRM },
+    { SIGCHLD },
+    { SIGCONT },
+    { SIGHUP },
+    { SIGINT },
+    { SIGPIPE },
+    { SIGQUIT },
+    { SIGTERM },
+    { SIGQUIT },
+    { SIGTERM },
+    { SIGTSTP },
+    { SIGTTIN },
+    { SIGTTOU },
+    { SIGUSR1 },
+    { SIGUSR2 },
+    { -1 }
+};
+
+/*
+ * Save signal handler state so it can be restored before exec.
+ */
+void
+save_signals(void)
+{
+    struct signal_state *ss;
+
+    for (ss = saved_signals; ss->signo != -1; ss++)
+	sigaction(ss->signo, NULL, &ss->sa);
+}
+
+/*
+ * Restore signal handlers to initial state.
+ */
+void
+restore_signals(void)
+{
+    struct signal_state *ss;
+
+    for (ss = saved_signals; ss->signo != -1; ss++)
+	sigaction(ss->signo, &ss->sa, NULL);
+}
+
 /*
  * Execute a command, potentially in a pty with I/O loggging.
  * This is a little bit tricky due to how POSIX job control works and
diff --git a/src/exec_pty.c b/src/exec_pty.c
index d9bd721b8..6a21f9e18 100644
--- a/src/exec_pty.c
+++ b/src/exec_pty.c
@@ -824,6 +824,7 @@ exec_monitor(struct command_details *details, char *argv[], char *envp[],
 	error(1, "cannot create pipe");
 
     /* Reset SIGWINCH and SIGALRM. */
+    /* XXX - restore all signals except SIGPIPE? */
     zero_bytes(&sa, sizeof(sa));
     sigemptyset(&sa.sa_mask);
     sa.sa_flags = SA_RESTART;
@@ -885,6 +886,7 @@ exec_monitor(struct command_details *details, char *argv[], char *envp[],
 	close(signal_pipe[1]);
 	close(errpipe[0]);
 	fcntl(errpipe[1], F_SETFD, FD_CLOEXEC);
+	restore_signals();
 
 	/* setup tty and exec command */
 	exec_pty(details, argv, envp);
@@ -1082,25 +1084,8 @@ flush_output(void)
 static void
 exec_pty(struct command_details *details, char *argv[], char *envp[])
 {
-    sigaction_t sa;
     pid_t self = getpid();
 
-    /* Reset signal handlers. */
-    zero_bytes(&sa, sizeof(sa));
-    sigemptyset(&sa.sa_mask);
-    sa.sa_flags = SA_RESTART;
-    sa.sa_handler = SIG_DFL;
-    sigaction(SIGHUP, &sa, NULL);
-    sigaction(SIGTERM, &sa, NULL);
-    sigaction(SIGINT, &sa, NULL);
-    sigaction(SIGQUIT, &sa, NULL);
-    sigaction(SIGTSTP, &sa, NULL);
-    sigaction(SIGTTIN, &sa, NULL);
-    sigaction(SIGTTOU, &sa, NULL);
-    sigaction(SIGUSR1, &sa, NULL);
-    sigaction(SIGUSR2, &sa, NULL);
-    sigaction(SIGCHLD, &sa, NULL);
-
     /* Set child process group here too to avoid a race. */
     setpgid(0, self);
 
diff --git a/src/sudo.h b/src/sudo.h
index aff081bbe..6402d82b2 100644
--- a/src/sudo.h
+++ b/src/sudo.h
@@ -167,6 +167,8 @@ void zero_bytes(volatile void *, size_t);
 /* exec.c */
 int sudo_execve(struct command_details *details, char *argv[], char *envp[],
     struct command_status *cstat);
+void save_signals(void);
+void restore_signals(void);
 
 /* term.c */
 int term_cbreak(int);