ujail: fix signal forwarding
[project/procd.git] / jail / jail.c
index b3f27d3..9d7483c 100644 (file)
@@ -25,6 +25,7 @@
 #include <libgen.h>
 #include <sched.h>
 #include <linux/limits.h>
+#include <signal.h>
 
 #include "capabilities.h"
 #include "elf.h"
@@ -129,6 +130,12 @@ static int build_jail_fs(void)
                return -1;
        }
 
+       /* oldroot can't be MS_SHARED else pivot_root() fails */
+       if (mount("none", "/", NULL, MS_REC|MS_PRIVATE, NULL)) {
+               ERROR("private mount failed %s\n", strerror(errno));
+               return -1;
+       }
+
        if (mount("tmpfs", jail_root, "tmpfs", MS_NOATIME, "mode=0755")) {
                ERROR("tmpfs mount failed %s\n", strerror(errno));
                return -1;
@@ -238,7 +245,7 @@ static int exec_jail(void *_notused)
                exit(EXIT_FAILURE);
        }
 
-       if (opts.namespace && opts.hostname
+       if (opts.namespace && opts.hostname && strlen(opts.hostname) > 0
                        && sethostname(opts.hostname, strlen(opts.hostname))) {
                ERROR("sethostname(%s) failed: %s\n", opts.hostname, strerror(errno));
                exit(EXIT_FAILURE);
@@ -263,8 +270,14 @@ static int exec_jail(void *_notused)
 static int jail_running = 1;
 static int jail_return_code = 0;
 
+static void jail_process_timeout_cb(struct uloop_timeout *t);
+static struct uloop_timeout jail_process_timeout = {
+       .cb = jail_process_timeout_cb,
+};
+
 static void jail_process_handler(struct uloop_process *c, int ret)
 {
+       uloop_timeout_cancel(&jail_process_timeout);
        if (WIFEXITED(ret)) {
                jail_return_code = WEXITSTATUS(ret);
                INFO("jail (%d) exited with exit: %d\n", c->pid, jail_return_code);
@@ -280,12 +293,25 @@ static struct uloop_process jail_process = {
        .cb = jail_process_handler,
 };
 
+static void jail_process_timeout_cb(struct uloop_timeout *t)
+{
+       DEBUG("jail process failed to stop, sending SIGKILL\n");
+       kill(jail_process.pid, SIGKILL);
+}
+
+static void jail_handle_signal(int signo)
+{
+       DEBUG("forwarding signal %d to the jailed process\n", signo);
+       kill(jail_process.pid, signo);
+}
+
 int main(int argc, char **argv)
 {
+       sigset_t sigmask;
        uid_t uid = getuid();
        char log[] = "/dev/log";
        char ubus[] = "/var/run/ubus.sock";
-       int ch;
+       int ch, i;
 
        if (uid) {
                ERROR("not root, aborting: %s\n", strerror(errno));
@@ -379,10 +405,30 @@ int main(int argc, char **argv)
                prctl(PR_SET_NAME, opts.name, NULL, NULL, NULL);
 
        uloop_init();
+
+       sigfillset(&sigmask);
+       for (i = 0; i < _NSIG; i++) {
+               struct sigaction s = { 0 };
+
+               if (!sigismember(&sigmask, i))
+                       continue;
+               if ((i == SIGCHLD) || (i == SIGPIPE))
+                       continue;
+
+               s.sa_handler = jail_handle_signal;
+               sigaction(i, &s, NULL);
+       }
+
        if (opts.namespace) {
-               jail_process.pid = clone(exec_jail,
-                       child_stack + STACK_SIZE,
-                       CLONE_NEWUTS | CLONE_NEWPID | CLONE_NEWNS | CLONE_NEWIPC | SIGCHLD, NULL);
+               add_mount("/dev/full", 0, -1);
+               add_mount("/dev/null", 0, -1);
+               add_mount("/dev/urandom", 0, -1);
+               add_mount("/dev/zero", 0, -1);
+
+               int flags = CLONE_NEWPID | CLONE_NEWNS | CLONE_NEWIPC | SIGCHLD;
+               if (opts.hostname)
+                       flags |= CLONE_NEWUTS;
+               jail_process.pid = clone(exec_jail, child_stack + STACK_SIZE, flags, NULL);
        } else {
                jail_process.pid = fork();
        }
@@ -391,12 +437,13 @@ int main(int argc, char **argv)
                /* parent process */
                uloop_process_add(&jail_process);
                uloop_run();
-               uloop_done();
                if (jail_running) {
                        DEBUG("uloop interrupted, killing jail process\n");
                        kill(jail_process.pid, SIGTERM);
-                       waitpid(jail_process.pid, NULL, 0);
+                       uloop_timeout_set(&jail_process_timeout, 1000);
+                       uloop_run();
                }
+               uloop_done();
                return jail_return_code;
        } else if (jail_process.pid == 0) {
                /* fork child process */