projects / thirdparty / systemd.git / blame
| Commit | Line | Data |
|---|---|---|
| 996d1697 TG |
1 | /*** |
| 2 | This file is part of systemd. | |
| 3 | ||
| 4 | Copyright (C) 2014 Axis Communications AB. All rights reserved. | |
| 5 | Copyright (C) 2015 Tom Gundersen | |
| 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 <arpa/inet.h> | |
| 23 | ||
| 24 | #include "util.h" | |
| 25 | #include "arp-util.h" | |
| 26 | ||
| 27 | int arp_network_bind_raw_socket(int ifindex, be32_t address, const struct ether_addr *eth_mac) { | |
| 28 | struct sock_filter filter[] = { | |
| 29 | BPF_STMT(BPF_LD + BPF_W + BPF_LEN, 0), /* A <- packet length */ | |
| 30 | BPF_JUMP(BPF_JMP + BPF_JGE + BPF_K, sizeof(struct ether_arp), 1, 0), /* packet >= arp packet ? */ | |
| 31 | BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */ | |
| 32 | BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(struct ether_arp, ea_hdr.ar_hrd)), /* A <- header */ | |
| 33 | BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPHRD_ETHER, 1, 0), /* header == ethernet ? */ | |
| 34 | BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */ | |
| 35 | BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(struct ether_arp, ea_hdr.ar_pro)), /* A <- protocol */ | |
| 36 | BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_IP, 1, 0), /* protocol == IP ? */ | |
| 37 | BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */ | |
| 38 | BPF_STMT(BPF_LD + BPF_B + BPF_ABS, offsetof(struct ether_arp, ea_hdr.ar_hln)), /* A <- hardware address length */ | |
| 39 | BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, sizeof(struct ether_addr), 1, 0), /* length == sizeof(ether_addr)? */ | |
| 40 | BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */ | |
| 41 | BPF_STMT(BPF_LD + BPF_B + BPF_ABS, offsetof(struct ether_arp, ea_hdr.ar_pln)), /* A <- protocol address length */ | |
| 42 | BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, sizeof(struct in_addr), 1, 0), /* length == sizeof(in_addr) ? */ | |
| 43 | BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */ | |
| 44 | BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(struct ether_arp, ea_hdr.ar_op)), /* A <- operation */ | |
| 45 | BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPOP_REQUEST, 2, 0), /* protocol == request ? */ | |
| 46 | BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPOP_REPLY, 1, 0), /* protocol == reply ? */ | |
| 47 | BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */ | |
| 48 | /* Sender Hardware Address must be different from our own */ | |
| 49 | BPF_STMT(BPF_LD + BPF_IMM, htobe32(*((uint32_t *) eth_mac))), /* A <- 4 bytes of client's MAC */ | |
| 50 | BPF_STMT(BPF_MISC + BPF_TAX, 0), /* X <- A */ | |
| 51 | BPF_STMT(BPF_LD + BPF_W + BPF_ABS, offsetof(struct ether_arp, arp_sha)), /* A <- 4 bytes of SHA */ | |
| 52 | BPF_STMT(BPF_ALU + BPF_XOR + BPF_X, 0), /* A xor X */ | |
| 53 | BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0, 0, 6), /* A == 0 ? */ | |
| 54 | BPF_STMT(BPF_LD + BPF_IMM, htobe16(*((uint16_t *) (((char *) eth_mac) + 4)))), /* A <- remainder of client's MAC */ | |
| 55 | BPF_STMT(BPF_MISC + BPF_TAX, 0), /* X <- A */ | |
| 56 | BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(struct ether_arp, arp_sha) + 4), /* A <- remainder of SHA */ | |
| 57 | BPF_STMT(BPF_ALU + BPF_XOR + BPF_X, 0), /* A xor X */ | |
| 58 | BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0, 0, 1), /* A == 0 ? */ | |
| 59 | BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */ | |
| 60 | /* Sender Protocol Address or Target Protocol Address must be equal to the one we care about*/ | |
| 61 | BPF_STMT(BPF_LD + BPF_IMM, htobe32(address)), /* A <- clients IP */ | |
| 62 | BPF_STMT(BPF_MISC + BPF_TAX, 0), /* X <- A */ | |
| 63 | BPF_STMT(BPF_LD + BPF_W + BPF_ABS, offsetof(struct ether_arp, arp_spa)), /* A <- SPA */ | |
| 64 | BPF_STMT(BPF_ALU + BPF_XOR + BPF_X, 0), /* X xor A */ | |
| 65 | BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0, 0, 1), /* A == 0 ? */ | |
| 66 | BPF_STMT(BPF_RET + BPF_K, 65535), /* return all */ | |
| 67 | BPF_STMT(BPF_LD + BPF_IMM, htobe32(address)), /* A <- clients IP */ | |
| 68 | BPF_STMT(BPF_MISC + BPF_TAX, 0), /* X <- A */ | |
| 69 | BPF_STMT(BPF_LD + BPF_W + BPF_ABS, offsetof(struct ether_arp, arp_tpa)), /* A <- TPA */ | |
| 70 | BPF_STMT(BPF_ALU + BPF_XOR + BPF_X, 0), /* X xor A */ | |
| 71 | BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0, 0, 1), /* A == 0 ? */ | |
| 72 | BPF_STMT(BPF_RET + BPF_K, 65535), /* return all */ | |
| 73 | BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */ | |
| 74 | }; | |
| 75 | struct sock_fprog fprog = { | |
| 76 | .len = ELEMENTSOF(filter), | |
| 77 | .filter = (struct sock_filter*) filter | |
| 78 | }; | |
| 79 | union sockaddr_union link = { | |
| 80 | .ll.sll_family = AF_PACKET, | |
| 81 | .ll.sll_protocol = htons(ETH_P_ARP), | |
| 82 | .ll.sll_ifindex = ifindex, | |
| 83 | .ll.sll_halen = ETH_ALEN, | |
| 84 | .ll.sll_addr = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff }, | |
| 85 | }; | |
| 86 | _cleanup_close_ int s = -1; | |
| 87 | int r; | |
| 88 | ||
| 89 | assert(ifindex > 0); | |
| 90 | ||
| 91 | s = socket(PF_PACKET, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0); | |
| 92 | if (s < 0) | |
| 93 | return -errno; | |
| 94 | ||
| 95 | r = setsockopt(s, SOL_SOCKET, SO_ATTACH_FILTER, &fprog, sizeof(fprog)); | |
| 96 | if (r < 0) | |
| 97 | return -errno; | |
| 98 | ||
| 99 | r = bind(s, &link.sa, sizeof(link.ll)); | |
| 100 | if (r < 0) | |
| 101 | return -errno; | |
| 102 | ||
| 103 | r = s; | |
| 104 | s = -1; | |
| 105 | ||
| 106 | return r; | |
| 107 | } | |
| 108 | ||
| 109 | static int arp_send_packet(int fd, int ifindex, | |
| 110 | be32_t pa, const struct ether_addr *ha, | |
| 111 | bool announce) { | |
| 112 | union sockaddr_union link = { | |
| 113 | .ll.sll_family = AF_PACKET, | |
| 114 | .ll.sll_protocol = htons(ETH_P_ARP), | |
| 115 | .ll.sll_ifindex = ifindex, | |
| 116 | .ll.sll_halen = ETH_ALEN, | |
| 117 | .ll.sll_addr = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff }, | |
| 118 | }; | |
| 119 | struct ether_arp arp = { | |
| 120 | .ea_hdr.ar_hrd = htons(ARPHRD_ETHER), /* HTYPE */ | |
| 121 | .ea_hdr.ar_pro = htons(ETHERTYPE_IP), /* PTYPE */ | |
| 122 | .ea_hdr.ar_hln = ETH_ALEN, /* HLEN */ | |
| 123 | .ea_hdr.ar_pln = sizeof(be32_t), /* PLEN */ | |
| 124 | .ea_hdr.ar_op = htons(ARPOP_REQUEST), /* REQUEST */ | |
| 125 | }; | |
| 126 | int r; | |
| 127 | ||
| 128 | assert(fd >= 0); | |
| 129 | assert(pa != 0); | |
| 130 | assert(ha); | |
| 131 | ||
| 132 | memcpy(&arp.arp_sha, ha, ETH_ALEN); | |
| 133 | memcpy(&arp.arp_tpa, &pa, sizeof(pa)); | |
| 134 | ||
| 135 | if (announce) | |
| 136 | memcpy(&arp.arp_spa, &pa, sizeof(pa)); | |
| 137 | ||
| 138 | r = sendto(fd, &arp, sizeof(struct ether_arp), 0, &link.sa, sizeof(link.ll)); | |
| 139 | if (r < 0) | |
| 140 | return -errno; | |
| 141 | ||
| 142 | return 0; | |
| 143 | } | |
| 144 | ||
| 145 | int arp_send_probe(int fd, int ifindex, | |
| 146 | be32_t pa, const struct ether_addr *ha) { | |
| 147 | return arp_send_packet(fd, ifindex, pa, ha, false); | |
| 148 | } | |
| 149 | ||
| 150 | int arp_send_announcement(int fd, int ifindex, | |
| 151 | be32_t pa, const struct ether_addr *ha) { | |
| 152 | return arp_send_packet(fd, ifindex, pa, ha, true); | |
| 153 | } |