isa/sudo
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

When execve() of the command fails, it is possible to receive SIGCHLD

Browse Source 
before we've read the error status from the pipe.  Re-order things
such that we send the final status at the very end and prefer error
status over wait status.
This commit is contained in:
Todd C. Miller
2010-05-20 07:33:14 -04:00
parent d2b8bad2a5
commit f8ff268318
1 changed files with 68 additions and 51 deletions
Download Patch File Download Diff File Expand all files Collapse all files

119
src/script.c
View File

@@ -496,7 +496,7 @@ script_execve(struct command_details *details, char *argv[], char *envp[],
int rbac_enabled = 0;
int log_io, maxfd;
cstat->type = 0; /* XXX */
cstat->type = CMD_INVALID;
log_io = !tq_empty(&io_plugins);
@@ -918,26 +918,69 @@ deliver_signal(pid_t pid, int signo)
static int
send_status(int fd, struct command_status *cstat)
{
int n;
int n = -1;
do {
n = send(fd, cstat, sizeof(*cstat), 0);
} while (n == -1 && errno == EINTR);
if (n != sizeof(*cstat)) {
sudo_debug(8, "unable to send status to parent: %s", strerror(errno));
} else {
sudo_debug(8, "sent status to parent");
if (cstat->type != CMD_INVALID) {
do {
n = send(fd, cstat, sizeof(*cstat), 0);
} while (n == -1 && errno == EINTR);
if (n != sizeof(*cstat)) {
sudo_debug(8, "unable to send status to parent: %s", strerror(errno));
} else {
sudo_debug(8, "sent status to parent");
}
cstat->type = CMD_INVALID; /* prevent re-sending */
}
return n;
}
/*
* Wait for child status after receiving SIGCHLD.
* If the child was stopped, the status is send back
* to the parent.
* Otherwise, cstat is filled in but not sent.
* Returns TRUE if child is still alive, else false.
*/
static int
handle_sigchld(int backchannel, struct command_status *cstat)
{
int status, alive = TRUE;
pid_t pid;
/* read child status */
do {
pid = waitpid(child, &status, WUNTRACED|WNOHANG);
} while (pid == -1 && errno == EINTR);
if (pid == child) {
if (cstat->type != CMD_ERRNO) {
cstat->type = CMD_WSTATUS;
cstat->val = status;
if (WIFSTOPPED(status)) {
sudo_debug(8, "command stopped, signal %d",
WSTOPSIG(status));
if (send_status(backchannel, cstat) == -1)
return alive; /* XXX */
} else if (WIFSIGNALED(status)) {
sudo_debug(8, "command killed, signal %d",
WTERMSIG(status));
} else {
sudo_debug(8, "command exited: %d",
WEXITSTATUS(status));
}
}
if (!WIFSTOPPED(status))
alive = FALSE;
}
return alive;
}
int
script_child(const char *path, char *argv[], char *envp[], int backchannel, int rbac)
{
struct command_status cstat;
struct timeval tv;
fd_set *fdsr;
sigaction_t sa;
pid_t pid;
int errpipe[2], maxfd, n, status;
int alive = TRUE;
@@ -1068,38 +1111,13 @@ script_child(const char *path, char *argv[], char *envp[], int backchannel, int
fdsr = (fd_set *)emalloc2(howmany(maxfd + 1, NFDBITS), sizeof(fd_mask));
zero_bytes(fdsr, howmany(maxfd + 1, NFDBITS) * sizeof(fd_mask));
zero_bytes(&cstat, sizeof(cstat));
tv.tv_sec = 0;
tv.tv_usec = 0;
for (;;) {
/* Read child status */
/* Read child status. */
if (recvsig[SIGCHLD]) {
recvsig[SIGCHLD] = FALSE;
/* read child status and relay to parent */
do {
pid = waitpid(child, &status, WUNTRACED|WNOHANG);
} while (pid == -1 && errno == EINTR);
if (pid == child) {
if (WIFSTOPPED(status)) {
sudo_debug(8, "command stopped, signal %d",
WSTOPSIG(status));
} else {
if (WIFSIGNALED(status))
sudo_debug(8, "command killed, signal %d",
WTERMSIG(status));
else
sudo_debug(8, "command exited: %d",
WEXITSTATUS(status));
alive = FALSE;
}
/* Send wait status unless we previously sent errno. */
if (cstat.type != CMD_ERRNO) {
cstat.type = CMD_WSTATUS;
cstat.val = status;
n = send_status(backchannel, &cstat);
if (n == -1)
goto done;
}
if (!alive)
goto done;
}
alive = handle_sigchld(backchannel, &cstat);
}
/* Check for signal on backchannel or errno on errpipe. */
@@ -1110,8 +1128,11 @@ script_child(const char *path, char *argv[], char *envp[], int backchannel, int
if (recvsig[SIGCHLD])
continue;
n = select(maxfd + 1, fdsr, NULL, NULL, NULL);
if (n == -1) {
/* If command exited we just poll, there may be data on errpipe. */
n = select(maxfd + 1, fdsr, NULL, NULL, alive ? NULL : &tv);
if (n <= 0) {
if (n == 0)
goto done;
if (errno == EINTR)
continue;
error(1, "select failed");
@@ -1126,15 +1147,6 @@ script_child(const char *path, char *argv[], char *envp[], int backchannel, int
warning("error reading from pipe");
goto done;
}
if (n == sizeof(cstat)) {
/* execve() failed, relay errno back to parent */
if (cstat.type == CMD_ERRNO) {
n = send_status(backchannel, &cstat);
if (n == -1)
goto done;
} else
warningx("unexpected reply type on pipe: %d", cstat.type);
}
/* Got errno or EOF, either way we are done with errpipe. */
FD_CLR(errpipe[0], fdsr);
close(errpipe[0]);
@@ -1158,8 +1170,13 @@ script_child(const char *path, char *argv[], char *envp[], int backchannel, int
}
done:
if (alive)
if (alive) {
/* XXX An error occurred, should send an error back. */
kill(child, SIGKILL);
} else {
/* Send parent status. */
send_status(backchannel, &cstat);
}
_exit(1);
bad: