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1 | /*** |
2 | This file is part of systemd. | |
3 | ||
4 | Copyright (C) 2014 Tom Gundersen | |
5 | Copyright (C) 2014 Susant Sahani | |
6 | ||
7 | systemd is free software; you can redistribute it and/or modify it | |
8 | under the terms of the GNU Lesser General Public License as published by | |
9 | the Free Software Foundation; either version 2.1 of the License, or | |
10 | (at your option) any later version. | |
11 | ||
12 | systemd is distributed in the hope that it will be useful, but | |
13 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
15 | Lesser General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU Lesser General Public License | |
18 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
19 | ***/ | |
20 | ||
21 | #include <linux/filter.h> | |
22 | #include <linux/if_ether.h> | |
23 | ||
3ffd4af2 | 24 | #include "fd-util.h" |
7a6f1457 | 25 | #include "lldp-internal.h" |
3ffd4af2 LP |
26 | #include "lldp-network.h" |
27 | #include "lldp-tlv.h" | |
28 | #include "socket-util.h" | |
ad1ad5c8 SS |
29 | |
30 | int lldp_network_bind_raw_socket(int ifindex) { | |
31 | typedef struct LLDPFrame { | |
32 | struct ethhdr hdr; | |
33 | uint8_t tlvs[0]; | |
34 | } LLDPFrame; | |
35 | ||
36 | struct sock_filter filter[] = { | |
37 | BPF_STMT(BPF_LD + BPF_W + BPF_ABS, offsetof(LLDPFrame, hdr.h_dest)), /* A <- 4 bytes of destination MAC */ | |
38 | BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0x0180c200, 1, 0), /* A != 01:80:c2:00 */ | |
39 | BPF_STMT(BPF_RET + BPF_K, 0), /* drop packet */ | |
40 | BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(LLDPFrame, hdr.h_dest) + 4), /* A <- remaining 2 bytes of destination MAC */ | |
41 | BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0x0000, 3, 0), /* A != 00:00 */ | |
42 | BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0x0003, 2, 0), /* A != 00:03 */ | |
43 | BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0x000e, 1, 0), /* A != 00:0e */ | |
44 | BPF_STMT(BPF_RET + BPF_K, 0), /* drop packet */ | |
45 | BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(LLDPFrame, hdr.h_proto)), /* A <- protocol */ | |
46 | BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_LLDP, 1, 0), /* A != ETHERTYPE_LLDP */ | |
47 | BPF_STMT(BPF_RET + BPF_K, 0), /* drop packet */ | |
48 | BPF_STMT(BPF_RET + BPF_K, (uint32_t) -1), /* accept packet */ | |
49 | }; | |
50 | ||
51 | struct sock_fprog fprog = { | |
52 | .len = ELEMENTSOF(filter), | |
53 | .filter = filter | |
54 | }; | |
55 | ||
56 | _cleanup_close_ int s = -1; | |
57 | ||
58 | union sockaddr_union saddrll = { | |
59 | .ll.sll_family = AF_PACKET, | |
60 | .ll.sll_ifindex = ifindex, | |
61 | }; | |
62 | ||
63 | int r; | |
64 | ||
65 | assert(ifindex > 0); | |
66 | ||
67 | s = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL)); | |
68 | if (s < 0) | |
69 | return -errno; | |
70 | ||
71 | r = setsockopt(s, SOL_SOCKET, SO_ATTACH_FILTER, &fprog, sizeof(fprog)); | |
72 | if (r < 0) | |
73 | return -errno; | |
74 | ||
75 | r = bind(s, &saddrll.sa, sizeof(saddrll.ll)); | |
76 | if (r < 0) | |
77 | return -errno; | |
78 | ||
79 | r = s; | |
80 | s = -1; | |
81 | ||
82 | return r; | |
83 | } |