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-rw-r--r--plugins/sudoers/visudo.c144
1 files changed, 83 insertions, 61 deletions
diff --git a/plugins/sudoers/visudo.c b/plugins/sudoers/visudo.c
index bc9b0645a..2f6289e28 100644
--- a/plugins/sudoers/visudo.c
+++ b/plugins/sudoers/visudo.c
@@ -94,7 +94,7 @@ static bool install_sudoers(struct sudoersfile *, bool, bool);
static bool visudo_track_error(const char *file, int line, int column, const char *fmt, va_list args) sudo_printf0like(4, 0);
static int print_unused(struct sudoers_parse_tree *, struct alias *, void *);
static bool reparse_sudoers(char *, int, char **, bool, bool);
-static int run_command(const char *, char *const *, bool);
+static int run_command(const char *, char *const *);
static void parse_sudoers_options(void);
static void setup_signals(void);
static void visudo_cleanup(void);
@@ -560,7 +560,7 @@ edit_sudoers(struct sudoersfile *sp, char *editor, int editor_argc,
goto done;
}
- if (run_command(editor, editor_argv, true) != -1) {
+ if (run_command(editor, editor_argv) != -1) {
if (sudo_gettime_real(&times[1]) == -1) {
sudo_warn("%s", U_("unable to read the clock"));
goto done;
@@ -823,7 +823,7 @@ install_sudoers(struct sudoersfile *sp, bool set_owner, bool set_mode)
av[3] = NULL;
/* And run it... */
- if (run_command(_PATH_MV, av, false) != 0) {
+ if (run_command(_PATH_MV, av) != 0) {
sudo_warnx(U_("command failed: '%s %s %s', %s unchanged"),
_PATH_MV, sp->tpath, sp->dpath, sp->opath);
goto done;
@@ -899,53 +899,37 @@ setup_signals(void)
}
static int
-run_command(const char *path, char *const *argv, bool foreground)
+run_command(const char *path, char *const *argv)
{
+ pid_t pid, visudo_pgrp = getpgrp();
int status, ttyfd = -1;
- pid_t pid, saved_pgrp = -1;
int rv = -1;
debug_decl(run_command, SUDOERS_DEBUG_UTIL);
- if (foreground) {
- /* Save original foreground process group id. */
- ttyfd = open(_PATH_TTY, O_RDWR);
- if (ttyfd != -1) {
- saved_pgrp = tcgetpgrp(ttyfd);
- if (saved_pgrp == -1) {
- sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,
- "%s: unable to get foreground pgrp", __func__);
- close(ttyfd);
- ttyfd = -1;
- }
- }
- if (ttyfd == -1)
- foreground = false;
- }
+ /* We may need access to /dev/tty to set the foreground process. */
+ ttyfd = open(_PATH_TTY, O_RDWR);
+ (void)fcntl(ttyfd, F_SETFD, FD_CLOEXEC);
switch (pid = sudo_debug_fork()) {
case -1:
sudo_fatal(U_("unable to execute %s"), path);
break; /* NOTREACHED */
case 0:
- /* Run command as the foreground process of a new process group. */
- if (foreground) {
- pid = getpid();
- if (setpgid(0, pid) == -1) {
- sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,
- "%s: unable to set pgrp to %d (editor)",
- __func__, (int)pid);
- } else {
- /* Wait for parent to grant us the controlling tty. */
- struct timespec ts = { 0, 1000 }; /* 1us */
- sudo_debug_printf(SUDO_DEBUG_DEBUG,
- "%s: waiting for controlling tty", __func__);
- while (tcgetpgrp(ttyfd) != pid)
- nanosleep(&ts, NULL);
- sudo_debug_printf(SUDO_DEBUG_DEBUG,
- "%s: got controlling tty", __func__);
- }
- close(ttyfd);
+ /*
+ * Run command in its own process group. If visudo is run
+ * in the foreground, it will make the editor the foreground
+ * process. There is a race between the parent's call to
+ * tcsetpgrp() and the child's execve(). If the parent loses
+ * the race, the child will be stopped with SIGTTOU or SIGTTIN
+ * and be restarted immeditately.
+ */
+ if (setpgid(0, 0) == -1) {
+ sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,
+ "%s: unable to set pgrp to %d (editor)",
+ __func__, (int)getpid());
}
+ sudo_debug_printf(SUDO_DEBUG_DEBUG, "%s: executing %s",
+ __func__, path);
closefrom(STDERR_FILENO + 1);
execv(path, argv);
sudo_warn(U_("unable to run %s"), path);
@@ -954,12 +938,17 @@ run_command(const char *path, char *const *argv, bool foreground)
}
/* Set child process group in both parent and child to avoid a race. */
- if (foreground) {
- if (setpgid(pid, pid) == -1) {
- sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,
- "%s: unable to set pgrp to %d (editor)",
- __func__, (int)pid);
- } else if (tcsetpgrp(ttyfd, pid) == -1) {
+ if (setpgid(pid, pid) == -1) {
+ sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,
+ "%s: unable to set pgrp to %d (editor)",
+ __func__, (int)pid);
+ } else if (tcgetpgrp(ttyfd) == visudo_pgrp) {
+ /*
+ * This races with execve() in the child. If we lose the race,
+ * the child may be stopped by SIGTTOU or SIGTTIN when it tries
+ * to use the terminal. That is handled by the waitpid() loop.
+ */
+ if (tcsetpgrp(ttyfd, pid) == -1) {
sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,
"%s: unable to set foreground pgrp to %d (editor)",
__func__, (int)pid);
@@ -985,10 +974,33 @@ run_command(const char *path, char *const *argv, bool foreground)
const int signo = WSTOPSIG(status);
sudo_debug_printf(SUDO_DEBUG_DIAG, "%s: %d: suspended by signal %d",
__func__, (int)pid, signo);
- if (foreground) {
- sudo_suspend_parent(signo, getpid(), getpgrp(), pid,
- NULL, NULL);
+ switch (signo) {
+ case SIGTTIN:
+ case SIGTTOU:
+ /*
+ * The editor stopped because it needs to be the foreground
+ * process. Try to make it the foreground process and continue
+ * (suspending visudo itself if running in the background).
+ */
+ if (ttyfd != -1) {
+ if (tcsetpgrp(ttyfd, pid) == 0) {
+ sudo_debug_printf(SUDO_DEBUG_DIAG, "%s: %d: continuing",
+ __func__, (int)pid);
+ killpg(pid, SIGCONT);
+ break;
+ } else {
+ sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,
+ "%s: unable to set foreground pgrp to %d (visudo)",
+ __func__, (int)visudo_pgrp);
+ }
+ }
+ FALLTHROUGH;
+ default:
+ killpg(visudo_pgrp, signo);
+ sudo_debug_printf(SUDO_DEBUG_DIAG, "%s: %d: continuing",
+ __func__, (int)pid);
killpg(pid, SIGCONT);
+ break;
}
} else {
sudo_debug_printf(SUDO_DEBUG_ERROR,
@@ -996,22 +1008,32 @@ run_command(const char *path, char *const *argv, bool foreground)
}
}
- if (foreground) {
- /* Restore the original foreground process group. */
- sigset_t mask, omask;
- sigemptyset(&mask);
- sigaddset(&mask, SIGTTOU);
- sigprocmask(SIG_BLOCK, &mask, &omask);
- sudo_debug_printf(SUDO_DEBUG_DEBUG,
- "%s: restoring foreground pgrp to %d (visudo)",
- __func__, (int)saved_pgrp);
- if (tcsetpgrp(ttyfd, saved_pgrp) == -1) {
- sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,
- "%s: unable to restore foreground pgrp to %d (visudo)",
- __func__, (int)saved_pgrp);
+ if (ttyfd != -1) {
+ pid = tcgetpgrp(ttyfd);
+ if (pid != -1 && pid != visudo_pgrp) {
+ /*
+ * If the foreground process does not exist it is usually because
+ * we made the editor the foreground process and it terminated.
+ * Change it back to visudo so we can prompt the user as needed.
+ */
+ if (kill(pid, 0) == -1 && errno == ESRCH) {
+ sigset_t mask, omask;
+ sigemptyset(&mask);
+ sigaddset(&mask, SIGTTOU);
+ sigprocmask(SIG_BLOCK, &mask, &omask);
+ sudo_debug_printf(SUDO_DEBUG_DEBUG,
+ "%s: changing foreground pgrp from %d to %d (visudo)",
+ __func__, (int)pid, (int)visudo_pgrp);
+ if (tcsetpgrp(ttyfd, visudo_pgrp) == -1) {
+ /* This should not fail since we block SIGTTOU. */
+ sudo_debug_printf(SUDO_DEBUG_ERROR|SUDO_DEBUG_ERRNO,
+ "%s: unable to restore foreground pgrp to %d (visudo)",
+ __func__, (int)visudo_pgrp);
+ }
+ sigprocmask(SIG_SETMASK, &omask, NULL);
+ }
}
close(ttyfd);
- sigprocmask(SIG_SETMASK, &omask, NULL);
}
debug_return_int(rv);
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