Implement a "subreaper" service flag

For particularly hostile daemons.

Signed-off-by: David Oberhollenzer <goliath@infraroot.at>

4 files changed, 32 insertions, 3 deletions

diff --git a/initd/init.h b/initd/init.h
index 9e18b96..b1287ee 100644
--- a/initd/init.h
+++ b/initd/init.h
@@ -16,6 +16,7 @@
 
 #include <linux/reboot.h>
 #include <sys/reboot.h>
+#include <sys/prctl.h>
 #include <stdbool.h>
 #include <signal.h>
 
diff --git a/initd/runsvc.c b/initd/runsvc.c
index b30e8e3..144490b 100644
--- a/initd/runsvc.c
+++ b/initd/runsvc.c
@@ -132,13 +132,13 @@ static __attribute__((noreturn)) void argv_exec(exec_t *e)
 	exit(EXIT_FAILURE);
 }
 
-static int run_sequentially(exec_t *list)
+static int run_sequentially(exec_t *list, bool direct_exec_last)
 {
 	pid_t ret, pid;
 	int status;
 
 	for (; list != NULL; list = list->next) {
-		if (list->next == NULL)
+		if (list->next == NULL && direct_exec_last)
 			argv_exec(list);
 
 		pid = fork();
@@ -169,6 +169,7 @@ pid_t runsvc(service_t *svc)
 {
 	sigset_t mask;
 	pid_t pid;
+	int ret;
 
 	pid = fork();
 
@@ -190,7 +191,15 @@ pid_t runsvc(service_t *svc)
 			exit(EXIT_FAILURE);
 		}
 
-		exit(run_sequentially(svc->exec));
+		if (svc->flags & SVC_FLAG_SUB_REAPER) {
+			prctl(PR_SET_CHILD_SUBREAPER, 1, 0, 0, 0);
+
+			ret = run_sequentially(svc->exec, false);
+		} else {
+			ret = run_sequentially(svc->exec, true);
+		}
+
+		exit(ret);
 	}
 
 	return pid;
diff --git a/lib/include/service.h b/lib/include/service.h
index 0fbf018..05ab8de 100644
--- a/lib/include/service.h
+++ b/lib/include/service.h
@@ -39,6 +39,8 @@ enum {
 	/* truncate stdout */
 	SVC_FLAG_TRUNCATE_OUT = 0x01,
 
+	SVC_FLAG_SUB_REAPER = 0x08,
+
 	SVC_FLAG_HAS_EXEC = 0x10,
 };
 
diff --git a/lib/init/rdsvc.c b/lib/init/rdsvc.c
index 09ed156..c461d98 100644
--- a/lib/init/rdsvc.c
+++ b/lib/init/rdsvc.c
@@ -204,6 +204,22 @@ static int svc_target(void *user, char *arg, rdline_t *rd)
 	return 0;
 }
 
+static int svc_subreaper(void *user, char *arg, rdline_t *rd)
+{
+	service_t *svc = user;
+
+	if (try_unescape(arg, rd))
+		return -1;
+
+	if (strcmp(arg, "yes") == 0 || strcmp(arg, "on") == 0 ||
+	    strcmp(arg, "true") == 0) {
+		svc->flags |= SVC_FLAG_SUB_REAPER;
+	} else {
+		svc->flags &= ~SVC_FLAG_SUB_REAPER;
+	}
+	return 0;
+}
+
 static const cfg_param_t svc_params[] = {
 	{ "description", 0, svc_desc },
 	{ "exec", 1, svc_exec },
@@ -212,6 +228,7 @@ static const cfg_param_t svc_params[] = {
 	{ "tty", 0, svc_tty },
 	{ "before", 0, svc_before },
 	{ "after", 0, svc_after },
+	{ "subreaper", 0, svc_subreaper },
 };
 
 service_t *rdsvc(int dirfd, const char *filename)