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Pass on SIGTSTP to the command if it was sent by a user process

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(not the kernel or the terminal) when we are not I/O logging and
set the default SIGTSTP handler when we re-send the signal to
ourself, restoring our handler after we resume.
This commit is contained in:
Todd C. Miller
2012-08-27 11:22:33 -04:00
parent 29907e357c
commit 37269d662a
1 changed files with 28 additions and 5 deletions
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33
src/exec.c
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@@ -98,8 +98,17 @@ static int fork_cmnd(struct command_details *details, int sv[2])
ppgrp = getpgrp(); /* parent's process group */
/*
* XXX - should only send SIGCONT when command pgrp != parent pgrp
* OR we were suspended by a user (not kernel or tty) signal.
* Handle suspend/restore of sudo and the command.
* In most cases, the command will be in the same process group as
* sudo and job control will "just work". However, if the command
* changes its process group ID and does not change it back (or is
* kill by SIGSTOP which is not catchable), we need to resume the
* command manually. Also, if SIGTSTP is sent directly to sudo,
* we need to suspend the command, and then suspend ourself, restoring
* the default SIGTSTP handler temporarily.
*
* XXX - currently we send SIGCONT upon resume in some cases where
* we don't need to (e.g. command pgrp == parent pgrp).
*/
zero_bytes(&sa, sizeof(sa));
sigemptyset(&sa.sa_mask);
@@ -111,6 +120,10 @@ static int fork_cmnd(struct command_details *details, int sv[2])
sa.sa_handler = handler;
#endif
sigaction(SIGCONT, &sa, NULL);
#ifdef SA_SIGINFO
sa.sa_sigaction = handler_user_only;
#endif
sigaction(SIGTSTP, &sa, NULL);
/*
* The policy plugin's session init must be run before we fork
@@ -548,16 +561,26 @@ handle_signals(int sv[2], pid_t child, int log_io, struct command_status *cstat)
* the child upon resume, potentially stopping sudo
* with SIGTTOU while the command continues to run.
*/
sigaction_t sa, osa;
pid_t saved_pgrp = (pid_t)-1;
int signo = WSTOPSIG(status);
int fd = open(_PATH_TTY, O_RDWR|O_NOCTTY, 0);
if (fd != -1) {
if ((saved_pgrp = tcgetpgrp(fd)) == ppgrp)
saved_pgrp = -1;
}
if (kill(getpid(), WSTOPSIG(status)) != 0) {
warning("kill(%d, SIG%s)", (int)getpid(),
strsigname(WSTOPSIG(status)));
if (signo == SIGTSTP) {
zero_bytes(&sa, sizeof(sa));
sigemptyset(&sa.sa_mask);
sa.sa_handler = SIG_DFL;
sigaction(SIGTSTP, &sa, NULL);
}
if (kill(getpid(), signo) != 0) {
warning("kill(%d, SIG%s)", (int)getpid(),
strsigname(signo));
}
if (signo == SIGTSTP)
sigaction(SIGTSTP, &osa, NULL);
if (fd != -1) {
/*
* Restore command's process group if different.