From 5267074938565976b105324ded8a8c5982bb8d5a Mon Sep 17 00:00:00 2001
From: David Härdeman <david@hardeman.nu>
Date: Tue, 16 Jun 2020 22:32:03 +0200
Subject: Make sure igmp socket filter is set and locked

---
 igmp.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

(limited to 'igmp.c')

diff --git a/igmp.c b/igmp.c
index 1c44769..14ba516 100644
--- a/igmp.c
+++ b/igmp.c
@@ -8,6 +8,7 @@
 #include <linux/bpf.h>
 #include <linux/filter.h>
 #include <arpa/inet.h>
+#include <errno.h>
 
 /* Remove later */
 #include <time.h>
@@ -488,6 +489,7 @@ igmp_init(struct cfg *cfg)
 	};
 	struct igmp *igmp;
 	int sfd;
+	int opt;
 
 	igmp = zmalloc(sizeof(*igmp));
 	if (!igmp)
@@ -499,14 +501,18 @@ igmp_init(struct cfg *cfg)
 	 */
 	sfd = socket(AF_PACKET, SOCK_DGRAM | SOCK_CLOEXEC, htons(ETH_P_ALL));
 	if (sfd < 0) {
-		perror("igmp socket");
+		if (errno == EACCES)
+			verbose("igmp socket: permission denied\n");
+		else
+			error("igmp socket: %m");
 		goto out_free;
 	}
 
-	if (setsockopt(sfd, SOL_SOCKET, SO_ATTACH_FILTER, &fprog, sizeof(fprog)) < 0) {
-		error("igmp setsockopt: %m");
-		goto out_fd;
-	}
+	if (setsockopt(sfd, SOL_SOCKET, SO_ATTACH_FILTER, &fprog, sizeof(fprog)) < 0)
+		perrordie("igmp setsockopt(SO_ATTACH_FILTER): %m");
+
+	if (setsockopt(sfd, SOL_SOCKET, SO_LOCK_FILTER, &opt, sizeof(opt)) < 0)
+		perrordie("igmp setsockopt(SO_LOCK_FILTER): %m");
 
 	/*
 	struct ifreq ifreq = {
-- 
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