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Terminate entire process group on Unix os_script and os_command timeout to avoid orphaned descendants

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This commit is contained in:
Andrea Mazzoleni 2026-09-05 09:45:42 +02:00
parent 11fee73ec4
commit b5a8ef7c33
1 changed files with 137 additions and 42 deletions
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179
os/unix.c
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@ -317,6 +317,11 @@ int filephy(const char* path, uint64_t size, uint64_t* physical)
/****************************************************************************/
/* exec */
/**
* Maximum execution time for helper scripts and commands, in seconds.
*/
#define OS_EXEC_TIMEOUT_SEC 300
/*
* Scrubbed environment
* Only provide the bare essentials.
@ -871,6 +876,104 @@ bail:
#endif
}
/**
* Waits for a process with a timeout, killing the entire process group if exceeded.
* Optionally delivers input to input_fd using non-blocking writes.
*/
static pid_t waitpid_timeout_group(pid_t pid, int* status, int64_t start, int input_fd, const char* input, int* timed_out, int* input_error)
{
size_t input_len = input != 0 ? strlen(input) : 0;
size_t input_pos = 0;
pid_t ret;
*timed_out = 0;
if (input_error != 0)
*input_error = 0;
while (1) {
ret = waitpid(pid, status, WNOHANG);
if (ret == pid) {
if (input_fd != -1)
close(input_fd);
return ret;
}
if (ret < 0) {
if (errno == EINTR)
continue;
int saved_errno = errno;
if (input_fd != -1)
close(input_fd);
errno = saved_errno;
return -1;
}
if (input_fd != -1) {
while (input_pos < input_len) {
ssize_t written = write(input_fd, input + input_pos, input_len - input_pos);
if (written > 0) {
input_pos += (size_t)written;
continue;
}
if (written == 0)
break;
if (errno == EINTR)
continue;
if (errno == EAGAIN || errno == EWOULDBLOCK)
break;
if (errno == EPIPE) {
close(input_fd);
input_fd = -1;
break;
}
if (input_error != 0)
*input_error = errno;
close(input_fd);
input_fd = -1;
break;
}
if (input_fd != -1 && input_pos == input_len) {
close(input_fd);
input_fd = -1;
}
}
if (os_tick_sec() - start >= OS_EXEC_TIMEOUT_SEC) {
*timed_out = 1;
if (input_fd != -1) {
close(input_fd);
input_fd = -1;
}
if (os_kill(pid) != 0 && errno != ESRCH)
return -1;
/* reap the process-group leader */
do {
ret = waitpid(pid, status, 0);
} while (ret < 0 && errno == EINTR);
return ret;
}
os_usleep(100000);
}
}
/**
* Executes a script directly via its file descriptor.
*/
@ -880,6 +983,7 @@ int os_script(char** argv, char** envp, const char* run_as_user)
pid_t pid;
int ret;
int status;
int timed_out;
int64_t start, stop;
struct os_user user;
@ -966,9 +1070,6 @@ int os_script(char** argv, char** envp, const char* run_as_user)
/* restore and unblock signals */
os_signal_restore_after_fork();
/* child will receive SIGALRM in 300 seconds (5 minutes) as a timeout */
alarm(300);
/* use the resolved path for execution */
argv[0] = resolved_path;
@ -1013,9 +1114,7 @@ int os_script(char** argv, char** envp, const char* run_as_user)
/* parent process */
close(fd);
do {
ret = waitpid(pid, &status, 0);
} while (ret == -1 && errno == EINTR);
ret = waitpid_timeout_group(pid, &status, start, -1, 0, &timed_out, 0);
if (ret == -1) {
os_syslog(OS_LVL_INFO, "failed to wait for script, path=%s, errno=%s(%d)", resolved_path, strerror(errno), errno);
@ -1024,6 +1123,13 @@ int os_script(char** argv, char** envp, const char* run_as_user)
stop = os_tick_sec();
int64_t execution_time = stop - start;
if (timed_out) {
os_syslog(OS_LVL_INFO, "script %s timeout after %" PRId64 " seconds", resolved_path, execution_time);
return 128 + SIGALRM;
}
if (execution_time > 30)
os_syslog(OS_LVL_WARNING, "script %s took %" PRId64 " seconds", resolved_path, execution_time);
@ -1037,11 +1143,8 @@ int os_script(char** argv, char** envp, const char* run_as_user)
} else if (WIFSIGNALED(status)) {
/* child died from a signal */
int sig = WTERMSIG(status);
if (sig == SIGALRM) {
os_syslog(OS_LVL_INFO, "script %s timeout after %" PRId64 " seconds", resolved_path, execution_time);
} else {
os_syslog(OS_LVL_INFO, "script %s terminated in %" PRId64 " seconds with signal %s(%d)", resolved_path, execution_time, os_signal_name(sig), sig);
}
os_syslog(OS_LVL_INFO, "script %s terminated in %" PRId64 " seconds with signal %s(%d)", resolved_path, execution_time, os_signal_name(sig), sig);
return 128 + sig;
} else {
/* in Linux it should never happen */
@ -1055,16 +1158,27 @@ int os_command(const char* command, const char* run_as_user, const char* stdin_t
pid_t pid;
int ret;
int status;
int timed_out;
int input_error;
int pipe_fds[2] = { -1, -1 };
int64_t start, stop;
struct os_user user;
/* create pipe only if we have text to send */
if (stdin_text != NULL) {
if (stdin_text != 0) {
if (pipe_cloexec(pipe_fds) < 0) {
os_syslog(OS_LVL_INFO, "failed to create input pipe, errno=%s(%d)", strerror(errno), errno);
return -1;
}
int flags = fcntl(pipe_fds[1], F_GETFL);
if (flags < 0 || fcntl(pipe_fds[1], F_SETFL, flags | O_NONBLOCK) < 0) {
os_syslog(OS_LVL_INFO, "failed to make input pipe non-blocking, errno=%s(%d)", strerror(errno), errno);
close(pipe_fds[0]);
close(pipe_fds[1]);
return -1;
}
}
if (os_user_lookup(run_as_user, &user) != 0) {
@ -1154,9 +1268,6 @@ int os_command(const char* command, const char* run_as_user, const char* stdin_t
/* restore and unblock signals */
os_signal_restore_after_fork();
/* child will receive SIGALRM in 300 seconds (5 minutes) as a timeout */
alarm(300);
char* const argv[] = { "sh", "-c", (char*)command, 0 };
execve("/bin/sh", argv, envp_scrubbed);
@ -1168,29 +1279,11 @@ int os_command(const char* command, const char* run_as_user, const char* stdin_t
if (pipe_fds[0] != -1)
close(pipe_fds[0]); /* close unused read end */
if (pipe_fds[1] != -1) {
/* write text to child's stdin */
size_t len = strlen(stdin_text);
size_t written = 0;
while (written < len) {
ssize_t ret_write = write(pipe_fds[1], stdin_text + written, len - written);
if (ret_write < 0) {
if (errno == EINTR)
continue;
if (errno == EPIPE)
break; /* child closed stdin early */
os_syslog(OS_LVL_INFO, "failed to write stdin to command %s, errno=%s(%d)", command, strerror(errno), errno);
break;
}
written += (size_t)ret_write;
}
/* closing the pipe sends EOF to the child (e.g., tells curl data is done) */
close(pipe_fds[1]);
}
ret = waitpid_timeout_group(pid, &status, start, pipe_fds[1], stdin_text, &timed_out, &input_error);
pipe_fds[1] = -1;
do {
ret = waitpid(pid, &status, 0);
} while (ret == -1 && errno == EINTR);
if (input_error != 0)
os_syslog(OS_LVL_INFO, "failed to write stdin to command %s, errno=%s(%d)", command, strerror(input_error), input_error);
if (ret == -1) {
os_syslog(OS_LVL_INFO, "failed to wait for command, command=%s, errno=%s(%d)", command, strerror(errno), errno);
@ -1199,6 +1292,12 @@ int os_command(const char* command, const char* run_as_user, const char* stdin_t
stop = os_tick_sec();
int64_t execution_time = stop - start;
if (timed_out) {
os_syslog(OS_LVL_INFO, "command %s timeout after %" PRId64 " seconds", command, execution_time);
return 128 + SIGALRM;
}
if (execution_time > 30)
os_syslog(OS_LVL_WARNING, "command %s ran for %" PRId64 " seconds that is unexpectedly long", command, execution_time);
@ -1212,11 +1311,7 @@ int os_command(const char* command, const char* run_as_user, const char* stdin_t
} else if (WIFSIGNALED(status)) {
/* child died from a signal */
int sig = WTERMSIG(status);
if (sig == SIGALRM) {
os_syslog(OS_LVL_INFO, "command %s timeout after %" PRId64 " seconds", command, execution_time);
} else {
os_syslog(OS_LVL_INFO, "command %s terminated in %" PRId64 " seconds with signal %s(%d)", command, execution_time, os_signal_name(sig), sig);
}
os_syslog(OS_LVL_INFO, "command %s terminated in %" PRId64 " seconds with signal %s(%d)", command, execution_time, os_signal_name(sig), sig);
return 128 + sig;
} else {
/* in Linux it should never happen */