78 lines
3.1 KiB
C
78 lines
3.1 KiB
C
/***
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This file is part of systemd.
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Copyright (C) 2014 Tom Gundersen
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Copyright (C) 2014 Susant Sahani
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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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 "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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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(PF_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 = bind(fd, &saddrll.sa, sizeof(saddrll.ll));
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if (r < 0)
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return -errno;
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r = fd;
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fd = -1;
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return r;
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}
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