journald: enforce some syntax restrictions on field names sent from the client side

[elogind.git] / src / journal / journald.c

diff --git a/src/journal/journald.c b/src/journal/journald.c
index 37f8f16754722b47f88ff81eecacaa67e744262a..d35e1c119ab5984604471f1ed08b240ecadc93c7 100644 (file)
--- a/src/journal/journald.c
+++ b/src/journal/journald.c
@@ -57,6 +57,7 @@ typedef struct Server {
 
         JournalMetrics metrics;
         uint64_t max_use;
+        bool compress;
 } Server;
 
 static void fix_perms(JournalFile *f, uid_t uid) {
@@ -146,6 +147,8 @@ static JournalFile* find_journal(Server *s, uid_t uid) {
                 return s->system_journal;
 
         fix_perms(f, uid);
+        f->metrics = s->metrics;
+        f->compress = s->compress;
 
         r = hashmap_put(s->user_journals, UINT32_TO_PTR(uid), f);
         if (r < 0) {
@@ -392,6 +395,41 @@ static void process_syslog_message(Server *s, const char *buf, struct ucred *ucr
         free(syslog_priority);
 }
 
+static bool valid_user_field(const char *p, size_t l) {
+        const char *a;
+
+        /* We kinda enforce POSIX syntax recommendations for
+           environment variables here, but make a couple of additional
+           requirements.
+
+           http://pubs.opengroup.org/onlinepubs/000095399/basedefs/xbd_chap08.html */
+
+        /* No empty field names */
+        if (l <= 0)
+                return false;
+
+        /* Don't allow names longer than 64 chars */
+        if (l > 64)
+                return false;
+
+        /* Variables starting with an underscore are protected */
+        if (p[0] == '_')
+                return false;
+
+        /* Don't allow digits as first character */
+        if (p[0] >= '0' && p[0] <= '9')
+                return false;
+
+        /* Only allow A-Z0-9 and '_' */
+        for (a = p; a < p + l; a++)
+                if (!((*a >= 'A' && *a <= 'Z') ||
+                      (*a >= '0' && *a <= '9') ||
+                      *a == '_'))
+                        return false;
+
+        return true;
+}
+
 static void process_native_message(Server *s, const void *buffer, size_t buffer_size, struct ucred *ucred, struct timeval *tv) {
         struct iovec *iovec = NULL;
         unsigned n = 0, m = 0, j;
@@ -425,8 +463,9 @@ static void process_native_message(Server *s, const void *buffer, size_t buffer_
                         continue;
                 }
 
-                if (*p == '.') {
-                        /* Control command, ignore for now */
+                if (*p == '.' || *p == '#') {
+                        /* Ignore control commands for now, and
+                         * comments too. */
                         remaining -= (e - p) + 1;
                         p = e + 1;
                         continue;
@@ -451,7 +490,7 @@ static void process_native_message(Server *s, const void *buffer, size_t buffer_
 
                 q = memchr(p, '=', e - p);
                 if (q) {
-                        if (p[0] != '_') {
+                        if (valid_user_field(p, q - p)) {
                                 /* If the field name starts with an
                                  * underscore, skip the variable,
                                  * since that indidates a trusted
@@ -492,7 +531,7 @@ static void process_native_message(Server *s, const void *buffer, size_t buffer_
                         k[e - p] = '=';
                         memcpy(k + (e - p) + 1, e + 1 + sizeof(uint64_t), l);
 
-                        if (k[0] != '_') {
+                        if (valid_user_field(p, e - p)) {
                                 iovec[n].iov_base = k;
                                 iovec[n].iov_len = (e - p) + 1 + l;
                                 n++;
@@ -661,6 +700,9 @@ static int system_journal_open(Server *s) {
         free(fn);
 
         if (r >= 0) {
+                s->system_journal->metrics = s->metrics;
+                s->system_journal->compress = s->compress;
+
                 fix_perms(s->system_journal, 0);
                 return r;
         }
@@ -685,6 +727,9 @@ static int system_journal_open(Server *s) {
                 return r;
         }
 
+        s->runtime_journal->metrics = s->metrics;
+        s->runtime_journal->compress = s->compress;
+
         fix_perms(s->runtime_journal, 0);
         return r;
 }
@@ -794,6 +839,7 @@ static int server_init(Server *s) {
         s->metrics.min_size = DEFAULT_MIN_SIZE;
         s->metrics.keep_free = DEFAULT_KEEP_FREE;
         s->max_use = DEFAULT_MAX_USE;
+        s->compress = true;
 
         s->epoll_fd = epoll_create1(EPOLL_CLOEXEC);
         if (s->epoll_fd < 0) {
@@ -931,6 +977,7 @@ int main(int argc, char *argv[]) {
         }
 
         log_set_target(LOG_TARGET_CONSOLE);
+        log_set_max_level(LOG_DEBUG);
         log_parse_environment();
         log_open();