mirror of
https://github.com/morgan9e/systemd
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5cdf13c70c
For libsystemd's headers, the changes made depend on whether the header is installed or not. For installed headers, the only change made is that commonly included headers were moved to _sd-common.h. For these headers, there should be no noticeable change in behavior when including them. For non-installed headers, includes were replaced with forward declarations where possible as usual. Split out of #37344.
140 lines
7.1 KiB
C
140 lines
7.1 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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/***
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Copyright © 2014 Axis Communications AB. All rights reserved.
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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 "arp-util.h"
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#include "ether-addr-util.h"
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#include "fd-util.h"
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#include "in-addr-util.h"
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#include "socket-util.h"
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#include "unaligned.h"
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int arp_update_filter(int fd, const struct in_addr *a, const struct ether_addr *mac) {
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struct sock_filter filter[] = {
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BPF_STMT(BPF_LD + BPF_W + BPF_LEN, 0), /* A <- packet length */
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BPF_JUMP(BPF_JMP + BPF_JGE + BPF_K, sizeof(struct ether_arp), 1, 0), /* packet >= arp packet ? */
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BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
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BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(struct ether_arp, ea_hdr.ar_hrd)), /* A <- header */
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BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPHRD_ETHER, 1, 0), /* header == ethernet ? */
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BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
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BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(struct ether_arp, ea_hdr.ar_pro)), /* A <- protocol */
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BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_IP, 1, 0), /* protocol == IP ? */
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BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
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BPF_STMT(BPF_LD + BPF_B + BPF_ABS, offsetof(struct ether_arp, ea_hdr.ar_hln)), /* A <- hardware address length */
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BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, sizeof(struct ether_addr), 1, 0), /* length == sizeof(ether_addr)? */
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BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
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BPF_STMT(BPF_LD + BPF_B + BPF_ABS, offsetof(struct ether_arp, ea_hdr.ar_pln)), /* A <- protocol address length */
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BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, sizeof(struct in_addr), 1, 0), /* length == sizeof(in_addr) ? */
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BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
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BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(struct ether_arp, ea_hdr.ar_op)), /* A <- operation */
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BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPOP_REQUEST, 2, 0), /* protocol == request ? */
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BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPOP_REPLY, 1, 0), /* protocol == reply ? */
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BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
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/* Sender Hardware Address must be different from our own */
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BPF_STMT(BPF_LDX + BPF_IMM, unaligned_read_be32(&mac->ether_addr_octet[0])), /* X <- 4 bytes of client's MAC */
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BPF_STMT(BPF_LD + BPF_W + BPF_ABS, offsetof(struct ether_arp, arp_sha)), /* A <- 4 bytes of SHA */
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BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_X, 0, 0, 4), /* A == X ? */
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BPF_STMT(BPF_LDX + BPF_IMM, unaligned_read_be16(&mac->ether_addr_octet[4])), /* X <- remainder of client's MAC */
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BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(struct ether_arp, arp_sha) + 4), /* A <- remainder of SHA */
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BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_X, 0, 0, 1), /* A == X ? */
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BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
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/* Sender Protocol Address or Target Protocol Address must be equal to the one we care about */
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BPF_STMT(BPF_LDX + BPF_IMM, htobe32(a->s_addr)), /* X <- clients IP */
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BPF_STMT(BPF_LD + BPF_W + BPF_ABS, offsetof(struct ether_arp, arp_spa)), /* A <- SPA */
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BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_X, 0, 0, 1), /* A == X ? */
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BPF_STMT(BPF_RET + BPF_K, UINT32_MAX), /* accept */
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BPF_STMT(BPF_LD + BPF_W + BPF_ABS, offsetof(struct ether_arp, arp_tpa)), /* A <- TPA */
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BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_X, 0, 0, 1), /* A == 0 ? */
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BPF_STMT(BPF_RET + BPF_K, UINT32_MAX), /* accept */
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BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
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};
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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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assert(fd >= 0);
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if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &fprog, sizeof(fprog)) < 0)
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return -errno;
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return 0;
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}
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int arp_network_bind_raw_socket(int ifindex, const struct in_addr *a, const struct ether_addr *mac) {
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union sockaddr_union link = {
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.ll.sll_family = AF_PACKET,
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.ll.sll_protocol = htobe16(ETH_P_ARP),
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.ll.sll_ifindex = ifindex,
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.ll.sll_halen = ETH_ALEN,
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.ll.sll_addr = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff },
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};
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_cleanup_close_ int s = -EBADF;
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int r;
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assert(ifindex > 0);
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assert(mac);
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s = socket(AF_PACKET, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0);
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if (s < 0)
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return -errno;
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r = arp_update_filter(s, a, mac);
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if (r < 0)
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return r;
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if (bind(s, &link.sa, sizeof(link.ll)) < 0)
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return -errno;
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return TAKE_FD(s);
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}
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int arp_send_packet(
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int fd,
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int ifindex,
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const struct in_addr *pa,
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const struct ether_addr *ha,
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bool announce) {
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union sockaddr_union link = {
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.ll.sll_family = AF_PACKET,
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.ll.sll_protocol = htobe16(ETH_P_ARP),
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.ll.sll_ifindex = ifindex,
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.ll.sll_halen = ETH_ALEN,
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.ll.sll_addr = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff },
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};
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struct ether_arp arp = {
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.ea_hdr.ar_hrd = htobe16(ARPHRD_ETHER), /* HTYPE */
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.ea_hdr.ar_pro = htobe16(ETHERTYPE_IP), /* PTYPE */
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.ea_hdr.ar_hln = ETH_ALEN, /* HLEN */
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.ea_hdr.ar_pln = sizeof(struct in_addr), /* PLEN */
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.ea_hdr.ar_op = htobe16(ARPOP_REQUEST), /* REQUEST */
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};
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ssize_t n;
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assert(fd >= 0);
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assert(ifindex > 0);
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assert(pa);
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assert(in4_addr_is_set(pa));
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assert(ha);
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assert(!ether_addr_is_null(ha));
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memcpy(&arp.arp_sha, ha, ETH_ALEN);
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memcpy(&arp.arp_tpa, pa, sizeof(struct in_addr));
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if (announce)
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memcpy(&arp.arp_spa, pa, sizeof(struct in_addr));
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n = sendto(fd, &arp, sizeof(struct ether_arp), 0, &link.sa, sizeof(link.ll));
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if (n < 0)
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return -errno;
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if (n != sizeof(struct ether_arp))
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return -EIO;
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return 0;
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}
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