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-rw-r--r--src/libsystemd-network/ipv4ll-network.c27
1 files changed, 27 insertions, 0 deletions
diff --git a/src/libsystemd-network/ipv4ll-network.c b/src/libsystemd-network/ipv4ll-network.c
index 9525408de9..b917fbf3ac 100644
--- a/src/libsystemd-network/ipv4ll-network.c
+++ b/src/libsystemd-network/ipv4ll-network.c
@@ -17,6 +17,8 @@
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
+#include <linux/filter.h>
+
#include "util.h"
#include "ipv4ll-internal.h"
@@ -33,6 +35,27 @@ int arp_network_send_raw_socket(int fd, const union sockaddr_union *link,
}
int arp_network_bind_raw_socket(int index, union sockaddr_union *link) {
+ struct sock_filter filter[] = {
+ BPF_STMT(BPF_LD + BPF_W + BPF_LEN, 0), /* A <- packet length */
+ BPF_JUMP(BPF_JMP + BPF_JGE + BPF_K, sizeof(struct ether_arp), 1, 0), /* packet >= arp packet ? */
+ BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
+ BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(struct ether_arp, ea_hdr.ar_hrd)), /* A <- header */
+ BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPHRD_ETHER, 1, 0), /* header == ethernet ? */
+ BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
+ BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(struct ether_arp, ea_hdr.ar_pro)), /* A <- protocol */
+ BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_IP, 1, 0), /* protocol == IP ? */
+ BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
+ BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(struct ether_arp, ea_hdr.ar_op)), /* A <- operation */
+ BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPOP_REQUEST, 0, 1), /* protocol == request ? */
+ BPF_STMT(BPF_RET + BPF_K, 65535), /* return all */
+ BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPOP_REPLY, 0, 1), /* protocol == reply ? */
+ BPF_STMT(BPF_RET + BPF_K, 65535), /* return all */
+ BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
+ };
+ struct sock_fprog fprog = {
+ .len = ELEMENTSOF(filter),
+ .filter = filter
+ };
int s;
assert(index > 0);
@@ -42,6 +65,10 @@ int arp_network_bind_raw_socket(int index, union sockaddr_union *link) {
if (s < 0)
return -errno;
+ if (setsockopt(s, SOL_SOCKET, SO_ATTACH_FILTER, &fprog, sizeof(fprog)) < 0) {
+ return -errno;
+ }
+
link->ll.sll_family = AF_PACKET;
link->ll.sll_protocol = htons(ETH_P_ARP);
link->ll.sll_ifindex = index;