s3: Allow child processes to exit gracefully if we are out of fds

When we run out of file descriptors for some reason, every new
connection forks a child that immediately panics causing smbd to
coredump.  This seems unnecessarily harsh; with this code change we
now catch that error and merely log a message about it and exit
without the core dump.

Signed-off-by: Tim Prouty <tprouty@samba.org>

9 files changed, 35 insertions, 25 deletions

diff --git a/source3/include/proto.h b/source3/include/proto.h
index c78d2c8e0b..717a972505 100644
--- a/source3/include/proto.h
+++ b/source3/include/proto.h
@@ -1106,7 +1106,7 @@ char *clean_name(TALLOC_CTX *ctx, const char *s);
 ssize_t write_data_at_offset(int fd, const char *buffer, size_t N, SMB_OFF_T pos);
 int set_blocking(int fd, bool set);
 void smb_msleep(unsigned int t);
-bool reinit_after_fork(struct messaging_context *msg_ctx,
+NTSTATUS reinit_after_fork(struct messaging_context *msg_ctx,
 		       struct event_context *ev_ctx,
 		       bool parent_longlived);
 bool yesno(const char *p);
diff --git a/source3/lib/util.c b/source3/lib/util.c
index 13f7e3c9ee..8e67edeae6 100644
--- a/source3/lib/util.c
+++ b/source3/lib/util.c
@@ -927,11 +927,11 @@ void smb_msleep(unsigned int t)
 #endif
 }
 
-bool reinit_after_fork(struct messaging_context *msg_ctx,
+NTSTATUS reinit_after_fork(struct messaging_context *msg_ctx,
 		       struct event_context *ev_ctx,
 		       bool parent_longlived)
 {
-	NTSTATUS status;
+	NTSTATUS status = NT_STATUS_OK;
 
 	/* Reset the state of the random
 	 * number generation system, so
@@ -942,7 +942,8 @@ bool reinit_after_fork(struct messaging_context *msg_ctx,
 	/* tdb needs special fork handling */
 	if (tdb_reopen_all(parent_longlived ? 1 : 0) == -1) {
 		DEBUG(0,("tdb_reopen_all failed.\n"));
-		return false;
+		status = NT_STATUS_OPEN_FAILED;
+		goto done;
 	}
 
 	if (ev_ctx) {
@@ -958,11 +959,10 @@ bool reinit_after_fork(struct messaging_context *msg_ctx,
 		if (!NT_STATUS_IS_OK(status)) {
 			DEBUG(0,("messaging_reinit() failed: %s\n",
 				 nt_errstr(status)));
-			return false;
 		}
 	}
-
-	return true;
+ done:
+	return status;
 }
 
 /****************************************************************************
diff --git a/source3/nmbd/asyncdns.c b/source3/nmbd/asyncdns.c
index 0736a66fb8..85729ae7ac 100644
--- a/source3/nmbd/asyncdns.c
+++ b/source3/nmbd/asyncdns.c
@@ -164,8 +164,8 @@ void start_async_dns(void)
 	CatchSignal(SIGHUP, SIG_IGN);
         CatchSignal(SIGTERM, SIGNAL_CAST sig_term );
 
-	if (!reinit_after_fork(nmbd_messaging_context(),
-			       nmbd_event_context(), true)) {
+	if (!NT_STATUS_IS_OK(reinit_after_fork(nmbd_messaging_context(),
+					       nmbd_event_context(), true))) {
 		DEBUG(0,("reinit_after_fork() failed\n"));
 		smb_panic("reinit_after_fork() failed");
 	}
diff --git a/source3/nmbd/nmbd.c b/source3/nmbd/nmbd.c
index daf4c295a6..903dc36d53 100644
--- a/source3/nmbd/nmbd.c
+++ b/source3/nmbd/nmbd.c
@@ -913,8 +913,8 @@ static bool open_sockets(bool isdaemon, int port)
 
 	pidfile_create("nmbd");
 
-	if (!reinit_after_fork(nmbd_messaging_context(),
-			       nmbd_event_context(), false)) {
+	if (!NT_STATUS_IS_OK(reinit_after_fork(nmbd_messaging_context(),
+					       nmbd_event_context(), false))) {
 		DEBUG(0,("reinit_after_fork() failed\n"));
 		exit(1);
 	}
diff --git a/source3/printing/print_cups.c b/source3/printing/print_cups.c
index 7edfb5edbe..18f42138c9 100644
--- a/source3/printing/print_cups.c
+++ b/source3/printing/print_cups.c
@@ -433,8 +433,8 @@ static bool cups_pcap_load_async(int *pfd)
 
 	close_all_print_db();
 
-	if (!reinit_after_fork(smbd_messaging_context(),
-			       smbd_event_context(), true)) {
+	if (!NT_STATUS_IS_OK(reinit_after_fork(smbd_messaging_context(),
+					       smbd_event_context(), true))) {
 		DEBUG(0,("cups_pcap_load_async: reinit_after_fork() failed\n"));
 		smb_panic("cups_pcap_load_async: reinit_after_fork() failed");
 	}
diff --git a/source3/printing/printing.c b/source3/printing/printing.c
index 3f337d01be..e73669fef5 100644
--- a/source3/printing/printing.c
+++ b/source3/printing/printing.c
@@ -1436,8 +1436,9 @@ void start_background_queue(void)
 		close(pause_pipe[0]);
 		pause_pipe[0] = -1;
 
-		if (!reinit_after_fork(smbd_messaging_context(),
-				       smbd_event_context(), true)) {
+		if (!NT_STATUS_IS_OK(reinit_after_fork(smbd_messaging_context(),
+						       smbd_event_context(),
+						       true))) {
 			DEBUG(0,("reinit_after_fork() failed\n"));
 			smb_panic("reinit_after_fork() failed");
 		}
diff --git a/source3/smbd/server.c b/source3/smbd/server.c
index 67836f785b..685b26fa1a 100644
--- a/source3/smbd/server.c
+++ b/source3/smbd/server.c
@@ -356,6 +356,7 @@ static void smbd_accept_connection(struct tevent_context *ev,
 
 	pid = sys_fork();
 	if (pid == 0) {
+		NTSTATUS status = NT_STATUS_OK;
 		/* Child code ... */
 		am_parent = 0;
 
@@ -374,10 +375,15 @@ static void smbd_accept_connection(struct tevent_context *ev,
 		talloc_free(s->parent);
 		s = NULL;
 
-		if (!reinit_after_fork(
-			    smbd_messaging_context(),
-			    smbd_event_context(),
-			    true)) {
+		status = reinit_after_fork(smbd_messaging_context(),
+					   smbd_event_context(), true);
+		if (!NT_STATUS_IS_OK(status)) {
+			if (NT_STATUS_EQUAL(status,
+					    NT_STATUS_TOO_MANY_OPENED_FILES)) {
+				DEBUG(0,("child process cannot initialize "
+					 "because too many files are open\n"));
+				goto exit;
+			}
 			DEBUG(0,("reinit_after_fork() failed\n"));
 			smb_panic("reinit_after_fork() failed");
 		}
@@ -386,6 +392,7 @@ static void smbd_accept_connection(struct tevent_context *ev,
 		smbd_setup_sig_hup_handler();
 
 		smbd_process();
+	 exit:
 		exit_server_cleanly("end of child");
 		return;
 	} else if (pid < 0) {
@@ -1122,8 +1129,8 @@ extern void build_options(bool screen);
 	if (is_daemon)
 		pidfile_create("smbd");
 
-	if (!reinit_after_fork(smbd_messaging_context(),
-			       smbd_event_context(), false)) {
+	if (!NT_STATUS_IS_OK(reinit_after_fork(smbd_messaging_context(),
+			     smbd_event_context(), false))) {
 		DEBUG(0,("reinit_after_fork() failed\n"));
 		exit(1);
 	}
diff --git a/source3/winbindd/winbindd.c b/source3/winbindd/winbindd.c
index e1ce223475..2b25616cf7 100644
--- a/source3/winbindd/winbindd.c
+++ b/source3/winbindd/winbindd.c
@@ -1304,8 +1304,9 @@ int main(int argc, char **argv, char **envp)
 	 * winbindd-specific resources we must free yet. JRA.
 	 */
 
-	if (!reinit_after_fork(winbind_messaging_context(),
-			       winbind_event_context(), false)) {
+	if (!NT_STATUS_IS_OK(reinit_after_fork(winbind_messaging_context(),
+					       winbind_event_context(),
+					       false))) {
 		DEBUG(0,("reinit_after_fork() failed\n"));
 		exit(1);
 	}
diff --git a/source3/winbindd/winbindd_dual.c b/source3/winbindd/winbindd_dual.c
index a69d34f30c..6fb0b5857c 100644
--- a/source3/winbindd/winbindd_dual.c
+++ b/source3/winbindd/winbindd_dual.c
@@ -1121,8 +1121,9 @@ bool winbindd_reinit_after_fork(const char *logfilename)
 	struct winbindd_domain *domain;
 	struct winbindd_child *cl;
 
-	if (!reinit_after_fork(winbind_messaging_context(),
-			       winbind_event_context(), true)) {
+	if (!NT_STATUS_IS_OK(reinit_after_fork(winbind_messaging_context(),
+					       winbind_event_context(),
+					       true))) {
 		DEBUG(0,("reinit_after_fork() failed\n"));
 		return false;
 	}