journalctl: complain if unprivileged users attempt to access the journal and persistant logging is off

TODO

@@ -61,14 +61,10 @@ Features:
 
 * testing tool for socket activation: some binary that listens on a socket and passes it on using the usual socket activation protocol to some server.
 
-* journald: add symlinks and device names to kernel messages
-
 * maybe make systemd-detect-virt suid? or use fscaps?
 
 * consider using __secure_getenv() instead of getenv() in libs
 
-* journald: automatic rekeying with no log messages doesn't appear to work
-
 * man: document in ExecStart= explicitly that we don't take shell command lines, only executable names with arguments
 
 * shutdown: don't read-only mount anything when running in container
@@ -135,14 +131,10 @@ Features:
 
 * switch-root: sockets need relabelling
 
-* segfault in journalctl during /var migration
-
 * systemd-analyze post-boot is broken for initrd
 
 * man: clarify that time-sync.target is not only sysv compat but also useful otherwise. Same for similar targets
 
-* journalctl should complain if run with uid != 0 and no persistent logs exist
-
 * .device aliases need to be implemented with the "following" logic, probably.
 
 * refuse taking lower-case variable names in sd_journal_send() and friends.
@@ -188,7 +180,7 @@ Features:
 
 * systemctl: when stopping a service which has triggres and warning about it actually check the TriggeredBy= deps fields
 
-* journal: hook up with EFI firmware log, new kmsg logic
+* journal: hook up with EFI firmware log
 
 * handle C-A-Del in logind, like the power/suspend buttons?
 

src/journal/journalctl.c

@@ -747,8 +747,20 @@ int main(int argc, char *argv[]) {
         }
 
 #ifdef HAVE_ACL
+        if (access("/var/log/journal", F_OK) < 0 && geteuid() != 0 && in_group("adm") <= 0) {
+                log_error("Unprivileged users can't see messages unless persistent log storage is enabled. Users in the group 'adm' can always see messages.");
+                r = -EACCES;
+                goto finish;
+        }
+
         if (!arg_quiet && geteuid() != 0 && in_group("adm") <= 0)
-                log_warning("Showing user generated messages only. Users in the group 'adm' can see all messages. Pass -q to turn this message off.");
+                log_warning("Showing user generated messages only. Users in the group 'adm' can see all messages. Pass -q to turn this notice off.");
+#else
+        if (geteuid() != 0 && in_group("adm") <= 0) {
+                log_error("No access to messages. Only users in the group 'adm' can see messages.");
+                r = -EACCES;
+                goto finish;
+        }
 #endif
 
         r = add_this_boot(j);

src/journal/journald.c

@@ -360,7 +360,8 @@ static void server_vacuum(Server *s) {
         sd_id128_to_string(machine, ids);
 
         if (s->system_journal) {
-                if (asprintf(&p, "/var/log/journal/%s", ids) < 0) {
+                p = strappend("/var/log/journal/", ids);
+                if (!p) {
                         log_oom();
                         return;
                 }
@@ -372,7 +373,8 @@ static void server_vacuum(Server *s) {
         }
 
         if (s->runtime_journal) {
-                if (asprintf(&p, "/run/log/journal/%s", ids) < 0) {
+                p = strappend("/run/log/journal/", ids);
+                if (!p) {
                         log_oom();
                         return;
                 }
@@ -1394,7 +1396,7 @@ static int server_init(Server *s) {
         return 0;
 }
 
-static void maybe_append_tags(Server *s) {
+static void server_maybe_append_tags(Server *s) {
 #ifdef HAVE_GCRYPT
         JournalFile *f;
         Iterator i;
@@ -1539,7 +1541,7 @@ int main(int argc, char *argv[]) {
                                 break;
                 }
 
-                maybe_append_tags(&server);
+                server_maybe_append_tags(&server);
         }
 
         log_debug("systemd-journald stopped as pid %lu", (unsigned long) getpid());