79 lines
3.2 KiB
C
79 lines
3.2 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#include <linux/filter.h>
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#include <netinet/if_ether.h>
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#include "fd-util.h"
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#include "lldp-network.h"
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#include "missing_network.h"
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#include "socket-util.h"
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int lldp_network_bind_raw_socket(int ifindex) {
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static const struct sock_filter filter[] = {
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BPF_STMT(BPF_LD + BPF_W + BPF_ABS, offsetof(struct ethhdr, h_dest)), /* A <- 4 bytes of destination MAC */
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BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0x0180c200, 1, 0), /* A != 01:80:c2:00 */
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BPF_STMT(BPF_RET + BPF_K, 0), /* drop packet */
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BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(struct ethhdr, h_dest) + 4), /* A <- remaining 2 bytes of destination MAC */
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BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0x0000, 3, 0), /* A != 00:00 */
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BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0x0003, 2, 0), /* A != 00:03 */
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BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0x000e, 1, 0), /* A != 00:0e */
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BPF_STMT(BPF_RET + BPF_K, 0), /* drop packet */
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BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(struct ethhdr, h_proto)), /* A <- protocol */
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BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_LLDP, 1, 0), /* A != ETHERTYPE_LLDP */
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BPF_STMT(BPF_RET + BPF_K, 0), /* drop packet */
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BPF_STMT(BPF_RET + BPF_K, (uint32_t) -1), /* accept packet */
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};
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static const struct sock_fprog fprog = {
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.len = ELEMENTSOF(filter),
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.filter = (struct sock_filter*) filter,
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};
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struct packet_mreq mreq = {
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.mr_ifindex = ifindex,
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.mr_type = PACKET_MR_MULTICAST,
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.mr_alen = ETH_ALEN,
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.mr_address = { 0x01, 0x80, 0xC2, 0x00, 0x00, 0x00 }
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};
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union sockaddr_union saddrll = {
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.ll.sll_family = AF_PACKET,
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.ll.sll_ifindex = ifindex,
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};
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_cleanup_close_ int fd = -1;
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int r;
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assert(ifindex > 0);
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fd = socket(AF_PACKET, SOCK_RAW|SOCK_CLOEXEC|SOCK_NONBLOCK,
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htobe16(ETHERTYPE_LLDP));
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if (fd < 0)
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return -errno;
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r = setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &fprog, sizeof(fprog));
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if (r < 0)
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return -errno;
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r = setsockopt(fd, SOL_PACKET, PACKET_ADD_MEMBERSHIP, &mreq, sizeof(mreq));
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if (r < 0)
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return -errno;
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mreq.mr_address[ETH_ALEN - 1] = 0x03;
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r = setsockopt(fd, SOL_PACKET, PACKET_ADD_MEMBERSHIP, &mreq, sizeof(mreq));
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if (r < 0)
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return -errno;
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mreq.mr_address[ETH_ALEN - 1] = 0x0E;
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r = setsockopt(fd, SOL_PACKET, PACKET_ADD_MEMBERSHIP, &mreq, sizeof(mreq));
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if (r < 0)
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return -errno;
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r = bind(fd, &saddrll.sa, sizeof(saddrll.ll));
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if (r < 0)
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return -errno;
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return TAKE_FD(fd);
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}
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