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Fix handling of SIGTTOU/SIGTTIN in program being run. We now only

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give the command the controlling tty if the main sudo process is the
foreground process.
This commit is contained in:
Todd C. Miller
2009-10-24 18:43:16 +00:00
parent 61b57817a5
commit c77ef16fcd
1 changed files with 122 additions and 47 deletions
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169
script.c
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@@ -100,10 +100,11 @@ static int child_status;
static char slavename[PATH_MAX];
static void script_child __P((char *path, char *argv[], int));
static void script_child __P((char *path, char *argv[], int, int));
static void script_run __P((char *path, char *argv[], int));
static void sync_winsize __P((int src, int dst));
static void sigchild __P((int s));
static void sigfgbg __P((int s));
static void sigtstp __P((int s));
static void sigwinch __P((int s));
static void flush_output __P((struct script_buf *output, struct timeval *then,
@@ -367,7 +368,7 @@ script_execv(path, argv)
sigaction_t sa, osa;
struct script_buf input, output;
struct timeval now, then;
int n, nready, exitcode = 1;
int foreground, n, nready, exitcode = 1;
fd_set *fdsr, *fdsw;
FILE *idfile;
#ifdef HAVE_ZLIB
@@ -404,20 +405,23 @@ script_execv(path, argv)
sigaction(SIGTTIN, &sa, NULL);
sigaction(SIGTTOU, &sa, NULL);
/* Are we the foreground process? */
parent = getpid(); /* so child can pass signals back to us */
foreground = tcgetpgrp(script_fds[SFD_USERTTY]) == parent;
/* XXX - should also catch terminal signals and kill child */
/*
* Child will run the command in the pty, parent will pass data
* to and from pty.
*/
parent = getpid(); /* so child can pass signals back to us */
child = fork();
switch (child) {
case -1:
log_error(USE_ERRNO, "fork");
break;
case 0:
script_child(path, argv, rbac_enabled);
script_child(path, argv, foreground, rbac_enabled);
/* NOTREACHED */
break;
}
@@ -490,7 +494,20 @@ script_execv(path, argv)
if (input.len > input.off)
FD_SET(script_fds[SFD_MASTER], fdsw);
if (suspended) {
switch (suspended) {
case SIGTTOU:
case SIGTTIN:
/*
* If we are the foreground process, just resume the child.
* Otherwise, re-send the signal with the handler disabled.
*/
if (tcgetpgrp(script_fds[SFD_USERTTY]) == parent) {
suspended = 0;
kill(child, SIGUSR1);
break;
}
/* FALLTHROUGH */
case SIGTSTP:
/* Flush any remaining output to master tty. */
flush_output(&output, &then, &now, ofile, tfile);
@@ -504,13 +521,29 @@ script_execv(path, argv)
sigaction(suspended, &sa, &osa);
kill(parent, suspended);
/* Set tty to raw mode, restore signal handler and resume child. */
do {
n = term_raw(script_fds[SFD_USERTTY], 1);
} while (!n && errno == EINTR);
/*
* If we were suspended due to tty I/O and sudo is still in
* the background, re-suspend.
*/
foreground = tcgetpgrp(script_fds[SFD_USERTTY]) == parent;
if (!foreground && (suspended == SIGTTOU || suspended == SIGTTIN))
kill(parent, suspended);
sigaction(suspended, &osa, NULL);
suspended = 0;
kill(child, SIGCONT);
if (foreground) {
/* Set tty to raw mode and tell child it is in foregound. */
do {
n = term_raw(script_fds[SFD_USERTTY], 1);
} while (!n && errno == EINTR);
kill(child, SIGUSR1);
} else {
/* Tell child it is in the background. */
kill(child, SIGUSR2);
}
break;
default:
break;
}
nready = select(script_fds[SFD_MASTER] + 1, fdsr, fdsw, NULL, NULL);
if (nready == -1) {
@@ -605,14 +638,15 @@ script_execv(path, argv)
}
void
script_child(path, argv, rbac_enabled)
script_child(path, argv, foreground, rbac_enabled)
char *path;
char *argv[];
int foreground;
int rbac_enabled;
{
sigaction_t sa;
pid_t pid;
int status, exitcode = 1;
pid_t pid, self = getpid();
int signo, status, exitcode = 1;
#ifndef TIOCSCTTY
int n;
#endif
@@ -628,6 +662,11 @@ script_child(path, argv, rbac_enabled)
sigaction(SIGTTIN, &sa, NULL);
sigaction(SIGTTOU, &sa, NULL);
/* Parent sends child SIGUSR1 to put command in the foreground. */
sa.sa_handler = sigfgbg;
sigaction(SIGUSR1, &sa, NULL);
sigaction(SIGUSR2, &sa, NULL);
/*
* Start a new session with the parent as the session leader
* and the slave pty as the controlling terminal.
@@ -671,10 +710,19 @@ script_child(path, argv, rbac_enabled)
warning("unable to execute %s", path);
_exit(127);
}
/* Set child process group and grant it the controlling tty. */
/*
* Put child in its own process group and make it the foreground
* process of the session if sudo itself is run in the foreground.
*/
setpgid(child, child);
if (tcsetpgrp(script_fds[SFD_SLAVE], child) != 0)
warning("tcsetpgrp");
if (foreground) {
do {
status = tcsetpgrp(script_fds[SFD_SLAVE], child);
} while (status == -1 && errno == EINTR);
if (status == -1)
warning("tcsetpgrp");
}
/* Wait for signal from child or for child to exit. */
for (;;) {
@@ -682,37 +730,55 @@ script_child(path, argv, rbac_enabled)
if (pid != child) {
if (pid == -1 && errno == EINTR)
continue;
/* no child? just exit */
/* either no child or a fatal error, just exit */
break;
}
/*
* If child stopped, signal parent and stop self.
* On resume, restart child and continue waiting.
*/
if (WIFSTOPPED(status)) {
/* Stop parent, self and then resume child when we come back */
kill(parent, WSTOPSIG(status));
kill(getpid(), SIGSTOP);
killpg(child, SIGCONT);
} else {
/* Child died, set exit code accordingly. */
if (WIFEXITED(status))
exitcode = WEXITSTATUS(status);
else if (WIFSIGNALED(status)) {
#ifdef HAVE_STRSIGNAL
int signo = WTERMSIG(status);
if (signo != SIGINT && signo != SIGPIPE) {
char *reason = strsignal(signo);
write(script_fds[SFD_MASTER], reason, strlen(reason));
if (WCOREDUMP(status))
write(script_fds[SFD_MASTER], " (core dumped)", 14);
write(script_fds[SFD_MASTER], "\n", 1);
}
#endif
exitcode = WTERMSIG(status) | 128;
}
/* If child exited or was killed we are done. */
if (!WIFSTOPPED(status))
break;
/*
* Child was stopped by signal, signal parent and stop self.
*/
suspended = 0;
signo = WSTOPSIG(status);
do {
/* Take back controlling tty while child is suspended. */
status = tcsetpgrp(script_fds[SFD_SLAVE], self);
} while (status == -1 && errno == EINTR);
kill(parent, signo);
/*
* Wait for parent to resume us, then continue child.
*/
do {
sigsuspend(&sa.sa_mask);
} while (suspended == 0);
if (suspended == SIGUSR1) {
/* Command is in the foreground, grant it controlling tty. */
do {
status = tcsetpgrp(script_fds[SFD_SLAVE], child);
} while (status == -1 && errno == EINTR);
}
killpg(child, SIGCONT);
}
if (pid == child) {
if (WIFEXITED(status)) {
exitcode = WEXITSTATUS(status);
} else if (WIFSIGNALED(status)) {
#ifdef HAVE_STRSIGNAL
signo = WTERMSIG(status);
if (signo != SIGINT && signo != SIGPIPE) {
char *reason = strsignal(signo);
write(script_fds[SFD_MASTER], reason, strlen(reason));
if (WCOREDUMP(status))
write(script_fds[SFD_MASTER], " (core dumped)", 14);
write(script_fds[SFD_MASTER], "\n", 1);
}
#endif
exitcode = WTERMSIG(status) | 128;
}
}
@@ -763,6 +829,9 @@ script_run(path, argv, rbac_enabled)
{
pid_t self = getpid();
/* Set child process group here too to avoid a race. */
setpgid(0, self);
/*
* We have guaranteed that the slave fd > 3
*/
@@ -781,10 +850,6 @@ script_run(path, argv, rbac_enabled)
close(script_fds[SFD_TIMING]);
close(script_fds[SFD_USERTTY]);
/* Spin until parent grants us the controlling pty */
while (tcgetpgrp(STDOUT_FILENO) != self)
continue;
#ifdef HAVE_SELINUX
if (rbac_enabled)
selinux_execv(path, argv);
@@ -812,6 +877,16 @@ sync_winsize(src, dst)
#endif
}
/*
* Signal handler for SIGUSR[12] in child
*/
static void
sigfgbg(s)
int s;
{
suspended = s;
}
/*
* Signal handler for child
*/