sd-journal: store and compare per-module static origin id

sd-journal objects use hashmaps, which use module-global state, so it is not safe
to pass a sd-journal object created by a module instance to another module instance
(e.g.: when two libraries static linking sd-journal are pulled in a single process).
Initialize a random per-module origin id and store it in the object, and compare
it when entering a public API, and error out if they don't match, together with
the PID.

3 files changed, 61 insertions, 48 deletions

diff --git a/src/libsystemd/sd-journal/journal-internal.h b/src/libsystemd/sd-journal/journal-internal.h
index 60e448dac0..259aac847d 100644
--- a/src/libsystemd/sd-journal/journal-internal.h
+++ b/src/libsystemd/sd-journal/journal-internal.h
@@ -87,7 +87,7 @@ struct sd_journal {
 
         Match *level0, *level1, *level2;
 
-        pid_t original_pid;
+        uint64_t origin_id;
 
         int inotify_fd;
         unsigned current_invalidate_counter, last_invalidate_counter;
diff --git a/src/libsystemd/sd-journal/sd-journal.c b/src/libsystemd/sd-journal/sd-journal.c
index 8964140f7a..b0194e875c 100644
--- a/src/libsystemd/sd-journal/sd-journal.c
+++ b/src/libsystemd/sd-journal/sd-journal.c
@@ -33,6 +33,7 @@
 #include "list.h"
 #include "lookup3.h"
 #include "nulstr-util.h"
+#include "origin-id.h"
 #include "path-util.h"
 #include "prioq.h"
 #include "process-util.h"
@@ -51,19 +52,12 @@
 
 #define DEFAULT_DATA_THRESHOLD (64*1024)
 
+DEFINE_PRIVATE_ORIGIN_ID_HELPERS(sd_journal, journal);
+
 static void remove_file_real(sd_journal *j, JournalFile *f);
 static int journal_file_read_tail_timestamp(sd_journal *j, JournalFile *f);
 static void journal_file_unlink_newest_by_bood_id(sd_journal *j, JournalFile *f);
 
-static bool journal_pid_changed(sd_journal *j) {
-        assert(j);
-
-        /* We don't support people creating a journal object and
-         * keeping it around over a fork(). Let's complain. */
-
-        return j->original_pid != getpid_cached();
-}
-
 static int journal_put_error(sd_journal *j, int r, const char *path) {
         _cleanup_free_ char *copy = NULL;
         int k;
@@ -234,7 +228,7 @@ _public_ int sd_journal_add_match(sd_journal *j, const void *data, size_t size)
         uint64_t hash;
 
         assert_return(j, -EINVAL);
-        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!journal_origin_changed(j), -ECHILD);
         assert_return(data, -EINVAL);
 
         if (size == 0)
@@ -330,7 +324,7 @@ fail:
 
 _public_ int sd_journal_add_conjunction(sd_journal *j) {
         assert_return(j, -EINVAL);
-        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!journal_origin_changed(j), -ECHILD);
 
         if (!j->level0)
                 return 0;
@@ -349,7 +343,7 @@ _public_ int sd_journal_add_conjunction(sd_journal *j) {
 
 _public_ int sd_journal_add_disjunction(sd_journal *j) {
         assert_return(j, -EINVAL);
-        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!journal_origin_changed(j), -ECHILD);
 
         if (!j->level0)
                 return 0;
@@ -406,7 +400,7 @@ char *journal_make_match_string(sd_journal *j) {
 }
 
 _public_ void sd_journal_flush_matches(sd_journal *j) {
-        if (!j)
+        if (!j || journal_origin_changed(j))
                 return;
 
         if (j->level0)
@@ -930,7 +924,7 @@ static int real_journal_next(sd_journal *j, direction_t direction) {
         int r;
 
         assert_return(j, -EINVAL);
-        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!journal_origin_changed(j), -ECHILD);
 
         r = iterated_cache_get(j->files_cache, NULL, &files, &n_files);
         if (r < 0)
@@ -988,7 +982,7 @@ static int real_journal_next_skip(sd_journal *j, direction_t direction, uint64_t
         int c = 0, r;
 
         assert_return(j, -EINVAL);
-        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!journal_origin_changed(j), -ECHILD);
         assert_return(skip <= INT_MAX, -ERANGE);
 
         if (skip == 0) {
@@ -1031,7 +1025,7 @@ _public_ int sd_journal_get_cursor(sd_journal *j, char **cursor) {
         int r;
 
         assert_return(j, -EINVAL);
-        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!journal_origin_changed(j), -ECHILD);
         assert_return(cursor, -EINVAL);
 
         if (!j->current_file || j->current_file->current_offset <= 0)
@@ -1064,7 +1058,7 @@ _public_ int sd_journal_seek_cursor(sd_journal *j, const char *cursor) {
         int r;
 
         assert_return(j, -EINVAL);
-        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!journal_origin_changed(j), -ECHILD);
         assert_return(!isempty(cursor), -EINVAL);
 
         for (const char *p = cursor;;) {
@@ -1160,7 +1154,7 @@ _public_ int sd_journal_test_cursor(sd_journal *j, const char *cursor) {
         Object *o;
 
         assert_return(j, -EINVAL);
-        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!journal_origin_changed(j), -ECHILD);
         assert_return(!isempty(cursor), -EINVAL);
 
         if (!j->current_file || j->current_file->current_offset <= 0)
@@ -1239,7 +1233,7 @@ _public_ int sd_journal_test_cursor(sd_journal *j, const char *cursor) {
 
 _public_ int sd_journal_seek_monotonic_usec(sd_journal *j, sd_id128_t boot_id, uint64_t usec) {
         assert_return(j, -EINVAL);
-        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!journal_origin_changed(j), -ECHILD);
 
         detach_location(j);
 
@@ -1255,7 +1249,7 @@ _public_ int sd_journal_seek_monotonic_usec(sd_journal *j, sd_id128_t boot_id, u
 
 _public_ int sd_journal_seek_realtime_usec(sd_journal *j, uint64_t usec) {
         assert_return(j, -EINVAL);
-        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!journal_origin_changed(j), -ECHILD);
 
         detach_location(j);
 
@@ -1270,7 +1264,7 @@ _public_ int sd_journal_seek_realtime_usec(sd_journal *j, uint64_t usec) {
 
 _public_ int sd_journal_seek_head(sd_journal *j) {
         assert_return(j, -EINVAL);
-        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!journal_origin_changed(j), -ECHILD);
 
         detach_location(j);
 
@@ -1283,7 +1277,7 @@ _public_ int sd_journal_seek_head(sd_journal *j) {
 
 _public_ int sd_journal_seek_tail(sd_journal *j) {
         assert_return(j, -EINVAL);
-        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!journal_origin_changed(j), -ECHILD);
 
         detach_location(j);
 
@@ -2001,7 +1995,7 @@ static sd_journal *journal_new(int flags, const char *path, const char *namespac
                 return NULL;
 
         *j = (sd_journal) {
-                .original_pid = getpid_cached(),
+                .origin_id = origin_id_query(),
                 .toplevel_fd = -EBADF,
                 .inotify_fd = -EBADF,
                 .flags = flags,
@@ -2254,7 +2248,7 @@ _public_ void sd_journal_close(sd_journal *j) {
         Directory *d;
         Prioq *p;
 
-        if (!j)
+        if (!j || journal_origin_changed(j))
                 return;
 
         while ((p = hashmap_first(j->newest_by_boot_id)))
@@ -2470,7 +2464,7 @@ _public_ int sd_journal_get_realtime_usec(sd_journal *j, uint64_t *ret) {
         int r;
 
         assert_return(j, -EINVAL);
-        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!journal_origin_changed(j), -ECHILD);
 
         f = j->current_file;
         if (!f)
@@ -2498,7 +2492,7 @@ _public_ int sd_journal_get_monotonic_usec(sd_journal *j, uint64_t *ret, sd_id12
         int r;
 
         assert_return(j, -EINVAL);
-        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!journal_origin_changed(j), -ECHILD);
 
         f = j->current_file;
         if (!f)
@@ -2543,7 +2537,7 @@ _public_ int sd_journal_get_seqnum(
         int r;
 
         assert_return(j, -EINVAL);
-        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!journal_origin_changed(j), -ECHILD);
 
         f = j->current_file;
         if (!f)
@@ -2597,7 +2591,7 @@ _public_ int sd_journal_get_data(sd_journal *j, const char *field, const void **
         int r;
 
         assert_return(j, -EINVAL);
-        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!journal_origin_changed(j), -ECHILD);
         assert_return(field, -EINVAL);
         assert_return(data, -EINVAL);
         assert_return(size, -EINVAL);
@@ -2654,7 +2648,7 @@ _public_ int sd_journal_enumerate_data(sd_journal *j, const void **data, size_t
         int r;
 
         assert_return(j, -EINVAL);
-        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!journal_origin_changed(j), -ECHILD);
         assert_return(data, -EINVAL);
         assert_return(size, -EINVAL);
 
@@ -2715,7 +2709,7 @@ _public_ int sd_journal_enumerate_available_data(sd_journal *j, const void **dat
 }
 
 _public_ void sd_journal_restart_data(sd_journal *j) {
-        if (!j)
+        if (!j || journal_origin_changed(j))
                 return;
 
         j->current_field = 0;
@@ -2743,7 +2737,7 @@ _public_ int sd_journal_get_fd(sd_journal *j) {
         int r;
 
         assert_return(j, -EINVAL);
-        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!journal_origin_changed(j), -ECHILD);
 
         if (j->no_inotify)
                 return -EMEDIUMTYPE;
@@ -2769,7 +2763,7 @@ _public_ int sd_journal_get_events(sd_journal *j) {
         int fd;
 
         assert_return(j, -EINVAL);
-        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!journal_origin_changed(j), -ECHILD);
 
         fd = sd_journal_get_fd(j);
         if (fd < 0)
@@ -2782,7 +2776,7 @@ _public_ int sd_journal_get_timeout(sd_journal *j, uint64_t *timeout_usec) {
         int fd;
 
         assert_return(j, -EINVAL);
-        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!journal_origin_changed(j), -ECHILD);
         assert_return(timeout_usec, -EINVAL);
 
         fd = sd_journal_get_fd(j);
@@ -2905,7 +2899,7 @@ _public_ int sd_journal_process(sd_journal *j) {
         bool got_something = false;
 
         assert_return(j, -EINVAL);
-        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!journal_origin_changed(j), -ECHILD);
 
         if (j->inotify_fd < 0) /* We have no inotify fd yet? Then there's noting to process. */
                 return 0;
@@ -2937,7 +2931,7 @@ _public_ int sd_journal_wait(sd_journal *j, uint64_t timeout_usec) {
         uint64_t t;
 
         assert_return(j, -EINVAL);
-        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!journal_origin_changed(j), -ECHILD);
 
         if (j->inotify_fd < 0) {
                 JournalFile *f;
@@ -2990,7 +2984,7 @@ _public_ int sd_journal_get_cutoff_realtime_usec(sd_journal *j, uint64_t *from,
         int r;
 
         assert_return(j, -EINVAL);
-        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!journal_origin_changed(j), -ECHILD);
         assert_return(from || to, -EINVAL);
         assert_return(from != to, -EINVAL);
 
@@ -3035,7 +3029,7 @@ _public_ int sd_journal_get_cutoff_monotonic_usec(
         int r;
 
         assert_return(j, -EINVAL);
-        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!journal_origin_changed(j), -ECHILD);
         assert_return(ret_from != ret_to, -EINVAL);
 
         ORDERED_HASHMAP_FOREACH(f, j->files) {
@@ -3088,7 +3082,7 @@ _public_ int sd_journal_get_usage(sd_journal *j, uint64_t *ret) {
         uint64_t sum = 0;
 
         assert_return(j, -EINVAL);
-        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!journal_origin_changed(j), -ECHILD);
         assert_return(ret, -EINVAL);
 
         ORDERED_HASHMAP_FOREACH(f, j->files) {
@@ -3116,7 +3110,7 @@ _public_ int sd_journal_query_unique(sd_journal *j, const char *field) {
         int r;
 
         assert_return(j, -EINVAL);
-        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!journal_origin_changed(j), -ECHILD);
         assert_return(!isempty(field), -EINVAL);
         assert_return(field_is_valid(field), -EINVAL);
 
@@ -3139,7 +3133,7 @@ _public_ int sd_journal_enumerate_unique(
         size_t k;
 
         assert_return(j, -EINVAL);
-        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!journal_origin_changed(j), -ECHILD);
         assert_return(j->unique_field, -EINVAL);
 
         k = strlen(j->unique_field);
@@ -3272,7 +3266,7 @@ _public_ int sd_journal_enumerate_available_unique(sd_journal *j, const void **d
 }
 
 _public_ void sd_journal_restart_unique(sd_journal *j) {
-        if (!j)
+        if (!j || journal_origin_changed(j))
                 return;
 
         j->unique_file = NULL;
@@ -3284,7 +3278,7 @@ _public_ int sd_journal_enumerate_fields(sd_journal *j, const char **field) {
         int r;
 
         assert_return(j, -EINVAL);
-        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!journal_origin_changed(j), -ECHILD);
         assert_return(field, -EINVAL);
 
         if (!j->fields_file) {
@@ -3423,7 +3417,7 @@ _public_ int sd_journal_enumerate_fields(sd_journal *j, const char **field) {
 }
 
 _public_ void sd_journal_restart_fields(sd_journal *j) {
-        if (!j)
+        if (!j || journal_origin_changed(j))
                 return;
 
         j->fields_file = NULL;
@@ -3434,7 +3428,7 @@ _public_ void sd_journal_restart_fields(sd_journal *j) {
 
 _public_ int sd_journal_reliable_fd(sd_journal *j) {
         assert_return(j, -EINVAL);
-        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!journal_origin_changed(j), -ECHILD);
 
         return !j->on_network;
 }
@@ -3466,7 +3460,7 @@ _public_ int sd_journal_get_catalog(sd_journal *j, char **ret) {
         int r;
 
         assert_return(j, -EINVAL);
-        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!journal_origin_changed(j), -ECHILD);
         assert_return(ret, -EINVAL);
 
         r = sd_journal_get_data(j, "MESSAGE_ID", &data, &size);
@@ -3501,7 +3495,7 @@ _public_ int sd_journal_get_catalog_for_message_id(sd_id128_t id, char **ret) {
 
 _public_ int sd_journal_set_data_threshold(sd_journal *j, size_t sz) {
         assert_return(j, -EINVAL);
-        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!journal_origin_changed(j), -ECHILD);
 
         j->data_threshold = sz;
         return 0;
@@ -3509,7 +3503,7 @@ _public_ int sd_journal_set_data_threshold(sd_journal *j, size_t sz) {
 
 _public_ int sd_journal_get_data_threshold(sd_journal *j, size_t *sz) {
         assert_return(j, -EINVAL);
-        assert_return(!journal_pid_changed(j), -ECHILD);
+        assert_return(!journal_origin_changed(j), -ECHILD);
         assert_return(sz, -EINVAL);
 
         *sz = j->data_threshold;
diff --git a/src/libsystemd/sd-journal/test-journal-init.c b/src/libsystemd/sd-journal/test-journal-init.c
index d5702db330..c8a19779f5 100644
--- a/src/libsystemd/sd-journal/test-journal-init.c
+++ b/src/libsystemd/sd-journal/test-journal-init.c
@@ -1,10 +1,14 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
+#include <unistd.h>
+
 #include "sd-journal.h"
 
 #include "chattr-util.h"
+#include "journal-internal.h"
 #include "log.h"
 #include "parse-util.h"
+#include "process-util.h"
 #include "rm-rf.h"
 #include "tests.h"
 
@@ -35,6 +39,21 @@ int main(int argc, char *argv[]) {
                 r = sd_journal_open_directory(&j, t, 0);
                 assert_se(r == 0);
 
+                assert_se(sd_journal_seek_head(j) == 0);
+                assert_se(j->current_location.type == LOCATION_HEAD);
+
+                r = safe_fork("(journal-fork-test)", FORK_WAIT|FORK_LOG, NULL);
+                if (r == 0) {
+                        assert_se(j);
+                        assert_se(sd_journal_get_realtime_usec(j, NULL) == -ECHILD);
+                        assert_se(sd_journal_seek_tail(j) == -ECHILD);
+                        assert_se(j->current_location.type == LOCATION_HEAD);
+                        sd_journal_close(j);
+                        _exit(EXIT_SUCCESS);
+                }
+
+                assert_se(r >= 0);
+
                 sd_journal_close(j);
 
                 j = NULL;