/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ /*** This file is part of systemd. Copyright (C) 2014 Tom Gundersen Copyright (C) 2014 Susant Sahani systemd is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. systemd is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with systemd; If not, see <http://www.gnu.org/licenses/>. ***/ #include <linux/filter.h> #include <linux/if_ether.h> #include "fd-util.h" #include "lldp-internal.h" #include "lldp-network.h" #include "lldp-tlv.h" #include "socket-util.h" int lldp_network_bind_raw_socket(int ifindex) { typedef struct LLDPFrame { struct ethhdr hdr; uint8_t tlvs[0]; } LLDPFrame; struct sock_filter filter[] = { BPF_STMT(BPF_LD + BPF_W + BPF_ABS, offsetof(LLDPFrame, hdr.h_dest)), /* A <- 4 bytes of destination MAC */ BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0x0180c200, 1, 0), /* A != 01:80:c2:00 */ BPF_STMT(BPF_RET + BPF_K, 0), /* drop packet */ BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(LLDPFrame, hdr.h_dest) + 4), /* A <- remaining 2 bytes of destination MAC */ BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0x0000, 3, 0), /* A != 00:00 */ BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0x0003, 2, 0), /* A != 00:03 */ BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0x000e, 1, 0), /* A != 00:0e */ BPF_STMT(BPF_RET + BPF_K, 0), /* drop packet */ BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(LLDPFrame, hdr.h_proto)), /* A <- protocol */ BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_LLDP, 1, 0), /* A != ETHERTYPE_LLDP */ BPF_STMT(BPF_RET + BPF_K, 0), /* drop packet */ BPF_STMT(BPF_RET + BPF_K, (uint32_t) -1), /* accept packet */ }; struct sock_fprog fprog = { .len = ELEMENTSOF(filter), .filter = filter }; _cleanup_close_ int s = -1; union sockaddr_union saddrll = { .ll.sll_family = AF_PACKET, .ll.sll_ifindex = ifindex, }; int r; assert(ifindex > 0); s = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL)); if (s < 0) return -errno; r = setsockopt(s, SOL_SOCKET, SO_ATTACH_FILTER, &fprog, sizeof(fprog)); if (r < 0) return -errno; r = bind(s, &saddrll.sa, sizeof(saddrll.ll)); if (r < 0) return -errno; r = s; s = -1; return r; }