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Remove extra flag to sudo_sigaction(). We want to trap the signal

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regardless of whether or not it is ignored by the underlying command
since there's no way to know what signal handlers the command will
install.  Now we just use sudo_sigaction() to set a flag in
saved_signals[] to indicate whether a signal needs to be restored
before exec.
This commit is contained in:
Todd C. Miller
2013-01-19 15:10:01 -05:00
parent a06a14838f
commit e764604485
4 changed files with 56 additions and 47 deletions
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28
src/exec.c
View File

@@ -113,11 +113,11 @@ static int fork_cmnd(struct command_details *details, int sv[2])
#else
sa.sa_handler = handler;
#endif
sudo_sigaction(SIGCONT, &sa, NULL, false);
sudo_sigaction(SIGCONT, &sa, NULL);
#ifdef SA_SIGINFO
sa.sa_sigaction = handler_user_only;
#endif
sudo_sigaction(SIGTSTP, &sa, NULL, true);
sudo_sigaction(SIGTSTP, &sa, NULL);
/*
* The policy plugin's session init must be run before we fork
@@ -247,12 +247,12 @@ sudo_execute(struct command_details *details, struct command_status *cstat)
#else
sa.sa_handler = handler;
#endif
sudo_sigaction(SIGTERM, &sa, NULL, true);
sudo_sigaction(SIGALRM, &sa, NULL, false); /* XXX - only if there is a timeout */
sudo_sigaction(SIGCHLD, &sa, NULL, false);
sudo_sigaction(SIGPIPE, &sa, NULL, false);
sudo_sigaction(SIGUSR1, &sa, NULL, true);
sudo_sigaction(SIGUSR2, &sa, NULL, true);
sudo_sigaction(SIGTERM, &sa, NULL);
sudo_sigaction(SIGALRM, &sa, NULL); /* XXX - only if there is a timeout */
sudo_sigaction(SIGCHLD, &sa, NULL);
sudo_sigaction(SIGPIPE, &sa, NULL);
sudo_sigaction(SIGUSR1, &sa, NULL);
sudo_sigaction(SIGUSR2, &sa, NULL);
/*
* When not running the command in a pty, we do not want to
@@ -267,9 +267,9 @@ sudo_execute(struct command_details *details, struct command_status *cstat)
sa.sa_sigaction = handler_user_only;
}
#endif
sudo_sigaction(SIGHUP, &sa, NULL, true);
sudo_sigaction(SIGINT, &sa, NULL, true);
sudo_sigaction(SIGQUIT, &sa, NULL, true);
sudo_sigaction(SIGHUP, &sa, NULL);
sudo_sigaction(SIGINT, &sa, NULL);
sudo_sigaction(SIGQUIT, &sa, NULL);
/* Max fd we will be selecting on. */
maxfd = MAX(sv[0], signal_pipe[0]);
@@ -514,12 +514,12 @@ dispatch_signals(int sv[2], pid_t child, int log_io, struct command_status *csta
sigemptyset(&sa.sa_mask);
sa.sa_flags = SA_RESTART;
sa.sa_handler = SIG_DFL;
sudo_sigaction(SIGTSTP, &sa, &osa, false);
sudo_sigaction(SIGTSTP, &sa, &osa);
}
if (kill(getpid(), signo) != 0)
warning("kill(%d, SIG%s)", (int)getpid(), signame);
if (signo == SIGTSTP)
sudo_sigaction(SIGTSTP, &osa, NULL, false);
sudo_sigaction(SIGTSTP, &osa, NULL);
if (fd != -1) {
/*
* Restore command's process group if different.
@@ -602,7 +602,7 @@ dispatch_pending_signals(struct command_status *cstat)
sigemptyset(&sa.sa_mask);
sa.sa_flags = SA_RESTART;
sa.sa_handler = SIG_DFL;
sudo_sigaction(SIGTSTP, &sa, NULL, false);
sudo_sigaction(SIGTSTP, &sa, NULL);
if (kill(getpid(), SIGTSTP) != 0)
warning("kill(%d, SIGTSTP)", (int)getpid());
/* No need to reinstall SIGTSTP handler. */

36
src/exec_pty.c
View File

@@ -380,7 +380,7 @@ suspend_parent(int signo)
sigemptyset(&sa.sa_mask);
sa.sa_flags = SA_RESTART;
sa.sa_handler = SIG_DFL;
sudo_sigaction(signo, &sa, &osa, false);
sudo_sigaction(signo, &sa, &osa);
}
sudo_debug_printf(SUDO_DEBUG_INFO, "kill parent SIG%s", signame);
if (killpg(ppgrp, signo) != 0)
@@ -413,7 +413,7 @@ suspend_parent(int signo)
}
if (signo != SIGSTOP)
sudo_sigaction(signo, &osa, NULL, false);
sudo_sigaction(signo, &osa, NULL);
rval = ttymode == TERM_RAW ? SIGCONT_FG : SIGCONT_BG;
break;
}
@@ -575,7 +575,7 @@ fork_pty(struct command_details *details, int sv[], int *maxfd, sigset_t *omask)
if (io_fds[SFD_USERTTY] != -1) {
sa.sa_flags = SA_RESTART;
sa.sa_handler = sigwinch;
sudo_sigaction(SIGWINCH, &sa, NULL, false);
sudo_sigaction(SIGWINCH, &sa, NULL);
}
/* So we can block tty-generated signals */
@@ -644,8 +644,8 @@ fork_pty(struct command_details *details, int sv[], int *maxfd, sigset_t *omask)
/* We don't want to receive SIGTTIN/SIGTTOU, getting EIO is preferable. */
sa.sa_handler = SIG_IGN;
sudo_sigaction(SIGTTIN, &sa, NULL, true);
sudo_sigaction(SIGTTOU, &sa, NULL, true);
sudo_sigaction(SIGTTIN, &sa, NULL);
sudo_sigaction(SIGTTOU, &sa, NULL);
/* Job control signals to relay from parent to child. */
sigfillset(&sa.sa_mask);
@@ -656,7 +656,7 @@ fork_pty(struct command_details *details, int sv[], int *maxfd, sigset_t *omask)
#else
sa.sa_handler = handler;
#endif
sudo_sigaction(SIGTSTP, &sa, NULL, true);
sudo_sigaction(SIGTSTP, &sa, NULL);
if (foreground) {
/* Copy terminal attrs from user tty -> pty slave. */
@@ -991,13 +991,13 @@ exec_monitor(struct command_details *details, int backchannel)
sigemptyset(&sa.sa_mask);
sa.sa_flags = SA_RESTART;
sa.sa_handler = SIG_DFL;
sudo_sigaction(SIGWINCH, &sa, NULL, false);
sudo_sigaction(SIGALRM, &sa, NULL, false); /* XXX - saved value */
sudo_sigaction(SIGWINCH, &sa, NULL);
sudo_sigaction(SIGALRM, &sa, NULL);
/* Ignore any SIGTTIN or SIGTTOU we get. */
sa.sa_handler = SIG_IGN;
sudo_sigaction(SIGTTIN, &sa, NULL, true);
sudo_sigaction(SIGTTOU, &sa, NULL, true);
sudo_sigaction(SIGTTIN, &sa, NULL);
sudo_sigaction(SIGTTOU, &sa, NULL);
/* Block all signals in mon_handler(). */
sigfillset(&sa.sa_mask);
@@ -1010,7 +1010,7 @@ exec_monitor(struct command_details *details, int backchannel)
#else
sa.sa_handler = mon_handler;
#endif
sudo_sigaction(SIGCHLD, &sa, NULL, false);
sudo_sigaction(SIGCHLD, &sa, NULL);
/* Catch common signals so we can cleanup properly. */
sa.sa_flags = SA_RESTART;
@@ -1020,13 +1020,13 @@ exec_monitor(struct command_details *details, int backchannel)
#else
sa.sa_handler = mon_handler;
#endif
sudo_sigaction(SIGHUP, &sa, NULL, true);
sudo_sigaction(SIGINT, &sa, NULL, true);
sudo_sigaction(SIGQUIT, &sa, NULL, true);
sudo_sigaction(SIGTERM, &sa, NULL, true);
sudo_sigaction(SIGTSTP, &sa, NULL, true);
sudo_sigaction(SIGUSR1, &sa, NULL, true);
sudo_sigaction(SIGUSR2, &sa, NULL, true);
sudo_sigaction(SIGHUP, &sa, NULL);
sudo_sigaction(SIGINT, &sa, NULL);
sudo_sigaction(SIGQUIT, &sa, NULL);
sudo_sigaction(SIGTERM, &sa, NULL);
sudo_sigaction(SIGTSTP, &sa, NULL);
sudo_sigaction(SIGUSR1, &sa, NULL);
sudo_sigaction(SIGUSR2, &sa, NULL);
/*
* Start a new session with the parent as the session leader

37
src/signal.c
View File

@@ -44,6 +44,7 @@ int signal_pipe[2];
static struct signal_state {
int signo;
int restore;
sigaction_t sa;
} saved_signals[] = {
{ SIGALRM }, /* SAVED_SIGALRM */
@@ -86,8 +87,10 @@ restore_signals(void)
struct signal_state *ss;
debug_decl(restore_signals, SUDO_DEBUG_MAIN)
for (ss = saved_signals; ss->signo != -1; ss++)
sigaction(ss->signo, &ss->sa, NULL);
for (ss = saved_signals; ss->signo != -1; ss++) {
if (ss->restore)
sigaction(ss->signo, &ss->sa, NULL);
}
debug_return;
}
@@ -146,22 +149,28 @@ init_signals(void)
}
/*
* Like sigaction() but includes an udpate_only flag.
* In update-only mode, don't override SIG_IGN.
* Like sigaction() but sets restore flag in saved_signals[]
* if needed.
*/
int
sudo_sigaction(int signo, struct sigaction *sa, struct sigaction *osa, bool update_only)
sudo_sigaction(int signo, struct sigaction *sa, struct sigaction *osa)
{
/* Don't override SIG_IGN if the update_only flag is set. */
if (update_only) {
struct signal_state *ss;
for (ss = saved_signals; ss->signo > 0; ss++) {
if (ss->signo == signo) {
if (ss->sa.sa_handler == SIG_IGN)
return 0;
break;
struct signal_state *ss;
int rval;
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;
}
}
return sigaction(signo, sa, osa);
rval = sigaction(signo, sa, osa);
debug_return_int(rval);
}

2
src/sudo.h
View File

@@ -267,7 +267,7 @@ char *get_process_ttyname(void);
/* signal.c */
struct sigaction;
extern int signal_pipe[2];
int sudo_sigaction(int signo, struct sigaction *sa, struct sigaction *osa, bool update_only);
int sudo_sigaction(int signo, struct sigaction *sa, struct sigaction *osa);
void init_signals(void);
void restore_signals(void);
void save_signals(void);