socket: add SocketUser= and SocketGroup= for chown()ing sockets in the file system

This is relatively complex, as we cannot invoke NSS from PID 1, and thus
need to fork a helper process temporarily.

1 files changed, 205 insertions, 77 deletions

diff --git a/src/core/socket.c b/src/core/socket.c
index c158aaf1de..e834b045a0 100644
--- a/src/core/socket.c
+++ b/src/core/socket.c
@@ -55,6 +55,7 @@
 static const UnitActiveState state_translation_table[_SOCKET_STATE_MAX] = {
         [SOCKET_DEAD] = UNIT_INACTIVE,
         [SOCKET_START_PRE] = UNIT_ACTIVATING,
+        [SOCKET_START_CHOWN] = UNIT_ACTIVATING,
         [SOCKET_START_POST] = UNIT_ACTIVATING,
         [SOCKET_LISTENING] = UNIT_ACTIVE,
         [SOCKET_RUNNING] = UNIT_ACTIVE,
@@ -147,6 +148,9 @@ static void socket_done(Unit *u) {
 
         strv_free(s->symlinks);
 
+        free(s->user);
+        free(s->group);
+
         s->timer_event_source = sd_event_source_unref(s->timer_event_source);
 }
 
@@ -592,6 +596,13 @@ static void socket_dump(Unit *u, FILE *f, const char *prefix) {
                         "%sSmackLabelIPOut: %s\n",
                         prefix, s->smack_ip_out);
 
+        if (!isempty(s->user) || !isempty(s->group))
+                fprintf(f,
+                        "%sOwnerUser: %s\n"
+                        "%sOwnerGroup: %s\n",
+                        prefix, strna(s->user),
+                        prefix, strna(s->group));
+
         LIST_FOREACH(port, p, s->ports) {
 
                 if (p->type == SOCKET_SOCKET) {
@@ -1207,6 +1218,7 @@ static void socket_set_state(Socket *s, SocketState state) {
 
         if (!IN_SET(state,
                     SOCKET_START_PRE,
+                    SOCKET_START_CHOWN,
                     SOCKET_START_POST,
                     SOCKET_STOP_PRE,
                     SOCKET_STOP_PRE_SIGTERM,
@@ -1225,6 +1237,7 @@ static void socket_set_state(Socket *s, SocketState state) {
                 socket_unwatch_fds(s);
 
         if (!IN_SET(state,
+                    SOCKET_START_CHOWN,
                     SOCKET_START_POST,
                     SOCKET_LISTENING,
                     SOCKET_RUNNING,
@@ -1250,14 +1263,16 @@ static int socket_coldplug(Unit *u) {
         if (s->deserialized_state == s->state)
                 return 0;
 
-        if (s->deserialized_state == SOCKET_START_PRE ||
-            s->deserialized_state == SOCKET_START_POST ||
-            s->deserialized_state == SOCKET_STOP_PRE ||
-            s->deserialized_state == SOCKET_STOP_PRE_SIGTERM ||
-            s->deserialized_state == SOCKET_STOP_PRE_SIGKILL ||
-            s->deserialized_state == SOCKET_STOP_POST ||
-            s->deserialized_state == SOCKET_FINAL_SIGTERM ||
-            s->deserialized_state == SOCKET_FINAL_SIGKILL) {
+        if (IN_SET(s->deserialized_state,
+                   SOCKET_START_PRE,
+                   SOCKET_START_CHOWN,
+                   SOCKET_START_POST,
+                   SOCKET_STOP_PRE,
+                   SOCKET_STOP_PRE_SIGTERM,
+                   SOCKET_STOP_PRE_SIGKILL,
+                   SOCKET_STOP_POST,
+                   SOCKET_FINAL_SIGTERM,
+                   SOCKET_FINAL_SIGKILL)) {
 
                 if (s->control_pid <= 0)
                         return -EBADMSG;
@@ -1271,12 +1286,14 @@ static int socket_coldplug(Unit *u) {
                         return r;
         }
 
-        if (s->deserialized_state == SOCKET_START_POST ||
-            s->deserialized_state == SOCKET_LISTENING ||
-            s->deserialized_state == SOCKET_RUNNING ||
-            s->deserialized_state == SOCKET_STOP_PRE ||
-            s->deserialized_state == SOCKET_STOP_PRE_SIGTERM ||
-            s->deserialized_state == SOCKET_STOP_PRE_SIGKILL) {
+        if (IN_SET(s->deserialized_state,
+                   SOCKET_START_CHOWN,
+                   SOCKET_START_POST,
+                   SOCKET_LISTENING,
+                   SOCKET_RUNNING,
+                   SOCKET_STOP_PRE,
+                   SOCKET_STOP_PRE_SIGTERM,
+                   SOCKET_STOP_PRE_SIGKILL)) {
                 r = socket_open_fds(s);
                 if (r < 0)
                         return r;
@@ -1293,9 +1310,9 @@ static int socket_coldplug(Unit *u) {
 }
 
 static int socket_spawn(Socket *s, ExecCommand *c, pid_t *_pid) {
+        _cleanup_free_ char **argv = NULL;
         pid_t pid;
         int r;
-        char **argv;
 
         assert(s);
         assert(c);
@@ -1333,22 +1350,100 @@ static int socket_spawn(Socket *s, ExecCommand *c, pid_t *_pid) {
                        s->exec_runtime,
                        &pid);
 
-        strv_free(argv);
+        r = unit_watch_pid(UNIT(s), pid);
         if (r < 0)
+                /* FIXME: we need to do something here */
                 goto fail;
 
+        *_pid = pid;
+        return 0;
+
+fail:
+        s->timer_event_source = sd_event_source_unref(s->timer_event_source);
+        return r;
+}
+
+static int socket_chown(Socket *s, pid_t *_pid) {
+        pid_t pid;
+        int r;
+
+        r = socket_arm_timer(s);
+        if (r < 0)
+                goto fail;
+
+        /* We have to resolve the user names out-of-process, hence
+         * let's fork here. It's messy, but well, what can we do? */
+
+        pid = fork();
+        if (pid < 0)
+                return -errno;
+
+        if (pid == 0) {
+                SocketPort *p;
+                uid_t uid = (uid_t) -1;
+                gid_t gid = (gid_t) -1;
+                int ret;
+
+                default_signals(SIGNALS_CRASH_HANDLER, SIGNALS_IGNORE, -1);
+                ignore_signals(SIGPIPE, -1);
+                log_forget_fds();
+
+                if (!isempty(s->user)) {
+                        const char *user = s->user;
+
+                        r = get_user_creds(&user, &uid, &gid, NULL, NULL);
+                        if (r < 0) {
+                                ret = EXIT_USER;
+                                goto fail_child;
+                        }
+                }
+
+                if (!isempty(s->group)) {
+                        const char *group = s->group;
+
+                        r = get_group_creds(&group, &gid);
+                        if (r < 0) {
+                                ret = EXIT_GROUP;
+                                goto fail_child;
+                        }
+                }
+
+                LIST_FOREACH(port, p, s->ports) {
+                        const char *path;
+
+                        if (p->type == SOCKET_SOCKET)
+                                path = socket_address_get_path(&p->address);
+                        else if (p->type == SOCKET_FIFO)
+                                path = p->path;
+
+                        if (!path)
+                                continue;
+
+                        if (chown(path, uid, gid) < 0) {
+                                r = -errno;
+                                ret = EXIT_CHOWN;
+                                goto fail_child;
+                        }
+                }
+
+                _exit(0);
+
+        fail_child:
+                log_open();
+                log_error("Failed to chown socket at step %s: %s", exit_status_to_string(ret, EXIT_STATUS_SYSTEMD), strerror(-r));
+
+                _exit(ret);
+        }
+
         r = unit_watch_pid(UNIT(s), pid);
         if (r < 0)
-                /* FIXME: we need to do something here */
                 goto fail;
 
         *_pid = pid;
-
         return 0;
 
 fail:
         s->timer_event_source = sd_event_source_unref(s->timer_event_source);
-
         return r;
 }
 
@@ -1376,11 +1471,12 @@ static void socket_enter_stop_post(Socket *s, SocketResult f) {
                 s->result = f;
 
         socket_unwatch_control_pid(s);
-
         s->control_command_id = SOCKET_EXEC_STOP_POST;
+        s->control_command = s->exec_command[SOCKET_EXEC_STOP_POST];
 
-        if ((s->control_command = s->exec_command[SOCKET_EXEC_STOP_POST])) {
-                if ((r = socket_spawn(s, s->control_command, &s->control_pid)) < 0)
+        if (s->control_command) {
+                r = socket_spawn(s, s->control_command, &s->control_pid);
+                if (r < 0)
                         goto fail;
 
                 socket_set_state(s, SOCKET_STOP_POST);
@@ -1448,11 +1544,12 @@ static void socket_enter_stop_pre(Socket *s, SocketResult f) {
                 s->result = f;
 
         socket_unwatch_control_pid(s);
-
         s->control_command_id = SOCKET_EXEC_STOP_PRE;
+        s->control_command = s->exec_command[SOCKET_EXEC_STOP_PRE];
 
-        if ((s->control_command = s->exec_command[SOCKET_EXEC_STOP_PRE])) {
-                if ((r = socket_spawn(s, s->control_command, &s->control_pid)) < 0)
+        if (s->control_command) {
+                r = socket_spawn(s, s->control_command, &s->control_pid);
+                if (r < 0)
                         goto fail;
 
                 socket_set_state(s, SOCKET_STOP_PRE);
@@ -1487,26 +1584,53 @@ static void socket_enter_start_post(Socket *s) {
         int r;
         assert(s);
 
+        socket_unwatch_control_pid(s);
+        s->control_command_id = SOCKET_EXEC_START_POST;
+        s->control_command = s->exec_command[SOCKET_EXEC_START_POST];
+
+        if (s->control_command) {
+                r = socket_spawn(s, s->control_command, &s->control_pid);
+                if (r < 0) {
+                        log_warning_unit(UNIT(s)->id, "%s failed to run 'start-post' task: %s", UNIT(s)->id, strerror(-r));
+                        goto fail;
+                }
+
+                socket_set_state(s, SOCKET_START_POST);
+        } else
+                socket_enter_listening(s);
+
+        return;
+
+fail:
+        socket_enter_stop_pre(s, SOCKET_FAILURE_RESOURCES);
+}
+
+static void socket_enter_start_chown(Socket *s) {
+        int r;
+
+        assert(s);
+
         r = socket_open_fds(s);
         if (r < 0) {
                 log_warning_unit(UNIT(s)->id, "%s failed to listen on sockets: %s", UNIT(s)->id, strerror(-r));
                 goto fail;
         }
 
-        socket_unwatch_control_pid(s);
+        if (!isempty(s->user) || !isempty(s->group)) {
 
-        s->control_command_id = SOCKET_EXEC_START_POST;
+                socket_unwatch_control_pid(s);
+                s->control_command_id = SOCKET_EXEC_START_CHOWN;
+                s->control_command = NULL;
 
-        if ((s->control_command = s->exec_command[SOCKET_EXEC_START_POST])) {
-                r = socket_spawn(s, s->control_command, &s->control_pid);
+                r = socket_chown(s, &s->control_pid);
                 if (r < 0) {
-                        log_warning_unit(UNIT(s)->id, "%s failed to run 'start-post' task: %s", UNIT(s)->id, strerror(-r));
+                        log_warning_unit(UNIT(s)->id, "%s failed to fork 'start-chown' task: %s", UNIT(s)->id, strerror(-r));
                         goto fail;
                 }
 
-                socket_set_state(s, SOCKET_START_POST);
+                socket_set_state(s, SOCKET_START_CHOWN);
         } else
-                socket_enter_listening(s);
+                socket_enter_start_post(s);
 
         return;
 
@@ -1519,22 +1643,23 @@ static void socket_enter_start_pre(Socket *s) {
         assert(s);
 
         socket_unwatch_control_pid(s);
-
         s->control_command_id = SOCKET_EXEC_START_PRE;
+        s->control_command = s->exec_command[SOCKET_EXEC_START_PRE];
 
-        if ((s->control_command = s->exec_command[SOCKET_EXEC_START_PRE])) {
+        if (s->control_command) {
                 r = socket_spawn(s, s->control_command, &s->control_pid);
-                if (r < 0)
+                if (r < 0) {
+                        log_warning_unit(UNIT(s)->id, "%s failed to run 'start-pre' task: %s", UNIT(s)->id, strerror(-r));
                         goto fail;
+                }
 
                 socket_set_state(s, SOCKET_START_PRE);
         } else
-                socket_enter_start_post(s);
+                socket_enter_start_chown(s);
 
         return;
 
 fail:
-        log_warning_unit(UNIT(s)->id, "%s failed to run 'start-pre' task: %s", UNIT(s)->id, strerror(-r));
         socket_enter_dead(s, SOCKET_FAILURE_RESOURCES);
 }
 
@@ -1709,16 +1834,19 @@ static int socket_start(Unit *u) {
 
         /* We cannot fulfill this request right now, try again later
          * please! */
-        if (s->state == SOCKET_STOP_PRE ||
-            s->state == SOCKET_STOP_PRE_SIGKILL ||
-            s->state == SOCKET_STOP_PRE_SIGTERM ||
-            s->state == SOCKET_STOP_POST ||
-            s->state == SOCKET_FINAL_SIGTERM ||
-            s->state == SOCKET_FINAL_SIGKILL)
+        if (IN_SET(s->state,
+                   SOCKET_STOP_PRE,
+                   SOCKET_STOP_PRE_SIGKILL,
+                   SOCKET_STOP_PRE_SIGTERM,
+                   SOCKET_STOP_POST,
+                   SOCKET_FINAL_SIGTERM,
+                   SOCKET_FINAL_SIGKILL))
                 return -EAGAIN;
 
-        if (s->state == SOCKET_START_PRE ||
-            s->state == SOCKET_START_POST)
+        if (IN_SET(s->state,
+                   SOCKET_START_PRE,
+                   SOCKET_START_CHOWN,
+                   SOCKET_START_POST))
                 return 0;
 
         /* Cannot run this without the service being around */
@@ -1764,18 +1892,21 @@ static int socket_stop(Unit *u) {
         assert(s);
 
         /* Already on it */
-        if (s->state == SOCKET_STOP_PRE ||
-            s->state == SOCKET_STOP_PRE_SIGTERM ||
-            s->state == SOCKET_STOP_PRE_SIGKILL ||
-            s->state == SOCKET_STOP_POST ||
-            s->state == SOCKET_FINAL_SIGTERM ||
-            s->state == SOCKET_FINAL_SIGKILL)
+        if (IN_SET(s->state,
+                   SOCKET_STOP_PRE,
+                   SOCKET_STOP_PRE_SIGTERM,
+                   SOCKET_STOP_PRE_SIGKILL,
+                   SOCKET_STOP_POST,
+                   SOCKET_FINAL_SIGTERM,
+                   SOCKET_FINAL_SIGKILL))
                 return 0;
 
         /* If there's already something running we go directly into
          * kill mode. */
-        if (s->state == SOCKET_START_PRE ||
-            s->state == SOCKET_START_POST) {
+        if (IN_SET(s->state,
+                   SOCKET_START_PRE,
+                   SOCKET_START_CHOWN,
+                   SOCKET_START_POST)) {
                 socket_enter_signal(s, SOCKET_STOP_PRE_SIGTERM, SOCKET_SUCCESS);
                 return -EAGAIN;
         }
@@ -2191,11 +2322,18 @@ static void socket_sigchld_event(Unit *u, pid_t pid, int code, int status) {
 
                 case SOCKET_START_PRE:
                         if (f == SOCKET_SUCCESS)
-                                socket_enter_start_post(s);
+                                socket_enter_start_chown(s);
                         else
                                 socket_enter_signal(s, SOCKET_FINAL_SIGTERM, f);
                         break;
 
+                case SOCKET_START_CHOWN:
+                        if (f == SOCKET_SUCCESS)
+                                socket_enter_start_post(s);
+                        else
+                                socket_enter_stop_pre(s, f);
+                        break;
+
                 case SOCKET_START_POST:
                         if (f == SOCKET_SUCCESS)
                                 socket_enter_listening(s);
@@ -2233,65 +2371,53 @@ static int socket_dispatch_timer(sd_event_source *source, usec_t usec, void *use
         switch (s->state) {
 
         case SOCKET_START_PRE:
-                log_warning_unit(UNIT(s)->id,
-                                 "%s starting timed out. Terminating.", UNIT(s)->id);
+                log_warning_unit(UNIT(s)->id, "%s starting timed out. Terminating.", UNIT(s)->id);
                 socket_enter_signal(s, SOCKET_FINAL_SIGTERM, SOCKET_FAILURE_TIMEOUT);
                 break;
 
+        case SOCKET_START_CHOWN:
         case SOCKET_START_POST:
-                log_warning_unit(UNIT(s)->id,
-                                 "%s starting timed out. Stopping.", UNIT(s)->id);
+                log_warning_unit(UNIT(s)->id, "%s starting timed out. Stopping.", UNIT(s)->id);
                 socket_enter_stop_pre(s, SOCKET_FAILURE_TIMEOUT);
                 break;
 
         case SOCKET_STOP_PRE:
-                log_warning_unit(UNIT(s)->id,
-                                 "%s stopping timed out. Terminating.", UNIT(s)->id);
+                log_warning_unit(UNIT(s)->id, "%s stopping timed out. Terminating.", UNIT(s)->id);
                 socket_enter_signal(s, SOCKET_STOP_PRE_SIGTERM, SOCKET_FAILURE_TIMEOUT);
                 break;
 
         case SOCKET_STOP_PRE_SIGTERM:
                 if (s->kill_context.send_sigkill) {
-                        log_warning_unit(UNIT(s)->id,
-                                         "%s stopping timed out. Killing.", UNIT(s)->id);
+                        log_warning_unit(UNIT(s)->id, "%s stopping timed out. Killing.", UNIT(s)->id);
                         socket_enter_signal(s, SOCKET_STOP_PRE_SIGKILL, SOCKET_FAILURE_TIMEOUT);
                 } else {
-                        log_warning_unit(UNIT(s)->id,
-                                         "%s stopping timed out. Skipping SIGKILL. Ignoring.",
-                                         UNIT(s)->id);
+                        log_warning_unit(UNIT(s)->id, "%s stopping timed out. Skipping SIGKILL. Ignoring.", UNIT(s)->id);
                         socket_enter_stop_post(s, SOCKET_FAILURE_TIMEOUT);
                 }
                 break;
 
         case SOCKET_STOP_PRE_SIGKILL:
-                log_warning_unit(UNIT(s)->id,
-                                 "%s still around after SIGKILL. Ignoring.", UNIT(s)->id);
+                log_warning_unit(UNIT(s)->id, "%s still around after SIGKILL. Ignoring.", UNIT(s)->id);
                 socket_enter_stop_post(s, SOCKET_FAILURE_TIMEOUT);
                 break;
 
         case SOCKET_STOP_POST:
-                log_warning_unit(UNIT(s)->id,
-                                 "%s stopping timed out (2). Terminating.", UNIT(s)->id);
+                log_warning_unit(UNIT(s)->id, "%s stopping timed out (2). Terminating.", UNIT(s)->id);
                 socket_enter_signal(s, SOCKET_FINAL_SIGTERM, SOCKET_FAILURE_TIMEOUT);
                 break;
 
         case SOCKET_FINAL_SIGTERM:
                 if (s->kill_context.send_sigkill) {
-                        log_warning_unit(UNIT(s)->id,
-                                         "%s stopping timed out (2). Killing.", UNIT(s)->id);
+                        log_warning_unit(UNIT(s)->id, "%s stopping timed out (2). Killing.", UNIT(s)->id);
                         socket_enter_signal(s, SOCKET_FINAL_SIGKILL, SOCKET_FAILURE_TIMEOUT);
                 } else {
-                        log_warning_unit(UNIT(s)->id,
-                                         "%s stopping timed out (2). Skipping SIGKILL. Ignoring.",
-                                         UNIT(s)->id);
+                        log_warning_unit(UNIT(s)->id, "%s stopping timed out (2). Skipping SIGKILL. Ignoring.", UNIT(s)->id);
                         socket_enter_dead(s, SOCKET_FAILURE_TIMEOUT);
                 }
                 break;
 
         case SOCKET_FINAL_SIGKILL:
-                log_warning_unit(UNIT(s)->id,
-                                 "%s still around after SIGKILL (2). Entering failed mode.",
-                                 UNIT(s)->id);
+                log_warning_unit(UNIT(s)->id, "%s still around after SIGKILL (2). Entering failed mode.", UNIT(s)->id);
                 socket_enter_dead(s, SOCKET_FAILURE_TIMEOUT);
                 break;
 
@@ -2440,6 +2566,7 @@ static int socket_get_timeout(Unit *u, uint64_t *timeout) {
 static const char* const socket_state_table[_SOCKET_STATE_MAX] = {
         [SOCKET_DEAD] = "dead",
         [SOCKET_START_PRE] = "start-pre",
+        [SOCKET_START_CHOWN] = "start-chown",
         [SOCKET_START_POST] = "start-post",
         [SOCKET_LISTENING] = "listening",
         [SOCKET_RUNNING] = "running",
@@ -2456,6 +2583,7 @@ DEFINE_STRING_TABLE_LOOKUP(socket_state, SocketState);
 
 static const char* const socket_exec_command_table[_SOCKET_EXEC_COMMAND_MAX] = {
         [SOCKET_EXEC_START_PRE] = "StartPre",
+        [SOCKET_EXEC_START_CHOWN] = "StartChown",
         [SOCKET_EXEC_START_POST] = "StartPost",
         [SOCKET_EXEC_STOP_PRE] = "StopPre",
         [SOCKET_EXEC_STOP_POST] = "StopPost"