*-daemon: always call setgroups, defaulting to count = 0origin/setgroups-zero

services started by init don't get any supplementary groups, but anything
started from a shell would inherit the groups, causing inconsistent
behaviour

we can either clear all groups, or always initalize root's groups. since
other init systems does not initialize anything, including us at boot,
let's just always clear them unconditionally

2 files changed, 19 insertions, 12 deletions

diff --git a/src/start-stop-daemon/start-stop-daemon.c b/src/start-stop-daemon/start-stop-daemon.c
index fdcd9032..54d74355 100644
--- a/src/start-stop-daemon/start-stop-daemon.c
+++ b/src/start-stop-daemon/start-stop-daemon.c
@@ -892,7 +892,7 @@ int main(int argc, char **argv)
 	/* Child process - lets go! */
 	if (pid == 0) {
 		gid_t group_buf[32], *group_list = group_buf;
-		int group_count = ARRAY_SIZE(group_buf);
+		int group_count = 0;
 		pid_t mypid = getpid();
 		close(pipefd[0]); /* Close the read end of the pipe. */
 		umask(numask);
@@ -950,10 +950,13 @@ int main(int argc, char **argv)
 					applet, pam_strerror(pamh, pamr));
 		}
 #endif
-		if (changeuser && getgrouplist(changeuser, gid, group_list, &group_count) < 0) {
-			group_list = xmalloc(group_count * sizeof(*group_list));
-			if (getgrouplist(changeuser, gid, group_list, &group_count) < 0)
-				eerrorx("%s: getgrouplist(%s, %"PRIuMAX")", applet, changeuser, (uintmax_t)gid);
+		if (changeuser) {
+			group_count = ARRAY_SIZE(group_buf);
+			if (getgrouplist(changeuser, gid, group_list, &group_count) < 0) {
+				group_list = xmalloc(group_count * sizeof(*group_list));
+				if (getgrouplist(changeuser, gid, group_list, &group_count) < 0)
+					eerrorx("%s: getgrouplist(%s, %"PRIuMAX")", applet, changeuser, (uintmax_t)gid);
+			}
 		}
 
 		/* Close any fd's to the passwd database */
@@ -980,7 +983,7 @@ int main(int argc, char **argv)
 		if (gid && setgid(gid))
 			eerrorx("%s: unable to set groupid to %"PRIuMAX,
 			    applet, (uintmax_t)gid);
-		if (changeuser && setgroups(group_count, group_list))
+		if (setgroups(group_count, group_list))
 			eerrorx("%s: setgroups() failed", applet);
 		if (group_list != group_buf)
 			free(group_list);
diff --git a/src/supervise-daemon/supervise-daemon.c b/src/supervise-daemon/supervise-daemon.c
index a1e87083..f1235f3b 100644
--- a/src/supervise-daemon/supervise-daemon.c
+++ b/src/supervise-daemon/supervise-daemon.c
@@ -384,7 +384,7 @@ RC_NORETURN static void child_process(char *exec, char **argv)
 	char start_time_string[20];
 	FILE *fp;
 	gid_t group_buf[32], *group_list = group_buf;
-	int group_count = ARRAY_SIZE(group_buf);
+	int group_count = 0;
 
 #ifdef HAVE_PAM
 	pam_handle_t *pamh = NULL;
@@ -445,10 +445,14 @@ RC_NORETURN static void child_process(char *exec, char **argv)
 	}
 #endif
 
-	if (changeuser && getgrouplist(changeuser, gid, group_list, &group_count) < 0) {
-		group_list = xmalloc(group_count * sizeof(*group_list));
-		if (getgrouplist(changeuser, gid, group_list, &group_count) < 0)
-			eerrorx("%s: getgrouplist(%s, %"PRIuMAX")", applet, changeuser, (uintmax_t)gid);
+	if (changeuser) {
+		/* getgrouplist is a stupid api. */
+		group_count = ARRAY_SIZE(group_buf);
+		if (getgrouplist(changeuser, gid, group_list, &group_count) < 0) {
+			group_list = xmalloc(group_count * sizeof(*group_list));
+			if (getgrouplist(changeuser, gid, group_list, &group_count) < 0)
+				eerrorx("%s: getgrouplist(%s, %"PRIuMAX")", applet, changeuser, (uintmax_t)gid);
+		}
 	}
 
 	/* Close any fd's to the passwd database */
@@ -462,7 +466,7 @@ RC_NORETURN static void child_process(char *exec, char **argv)
 
 	if (gid && setgid(gid))
 		eerrorx("%s: unable to set groupid to %"PRIuMAX, applet, (uintmax_t)gid);
-	if (changeuser && setgroups(group_count, group_list) < 0)
+	if (setgroups(group_count, group_list) < 0)
 		eerrorx("%s: setgroups() failed", applet);
 	if (group_list != group_buf)
 		free(group_list);