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[thirdparty/systemd.git] / src / libsystemd-network / dhcp-network.c
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db9ecf05 1/* SPDX-License-Identifier: LGPL-2.1-or-later */
8b4a9693 2/***
810adae9 3 Copyright © 2013 Intel Corporation. All rights reserved.
8b4a9693
PF
4***/
5
edda10f2
FS
6#include <linux/filter.h>
7#include <linux/if_infiniband.h>
8#include <linux/if_packet.h>
7429b07f 9#include <net/if_arp.h>
8b4a9693 10#include <stdio.h>
3ffd4af2 11#include <string.h>
8b4a9693 12
9bcbb614
YW
13#include "dhcp-network.h"
14#include "dhcp-protocol.h"
5cdf13c7 15#include "ether-addr-util.h"
3ffd4af2 16#include "fd-util.h"
5cdf13c7 17#include "socket-util.h"
f11cba74 18#include "unaligned.h"
8b4a9693 19
073a1daa
YW
20static int _bind_raw_socket(
21 int ifindex,
22 union sockaddr_union *link,
23 uint32_t xid,
24 const struct hw_addr_data *hw_addr,
25 const struct hw_addr_data *bcast_addr,
26 uint16_t arp_type,
ea577968 27 uint16_t port,
28 bool so_priority_set,
29 int so_priority) {
073a1daa
YW
30
31 assert(ifindex > 0);
32 assert(link);
33 assert(hw_addr);
34 assert(bcast_addr);
35 assert(IN_SET(arp_type, ARPHRD_ETHER, ARPHRD_INFINIBAND));
36
37 switch (arp_type) {
38 case ARPHRD_ETHER:
39 assert(hw_addr->length == ETH_ALEN);
40 assert(bcast_addr->length == ETH_ALEN);
41 break;
42 case ARPHRD_INFINIBAND:
43 assert(hw_addr->length == 0);
44 assert(bcast_addr->length == INFINIBAND_ALEN);
45 break;
46 default:
47 assert_not_reached();
48 }
49
bc29e507 50 struct sock_filter filter[] = {
088b6ba2
LP
51 BPF_STMT(BPF_LD + BPF_W + BPF_LEN, 0), /* A <- packet length */
52 BPF_JUMP(BPF_JMP + BPF_JGE + BPF_K, sizeof(DHCPPacket), 1, 0), /* packet >= DHCPPacket ? */
53 BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
54 BPF_STMT(BPF_LD + BPF_B + BPF_ABS, offsetof(DHCPPacket, ip.protocol)), /* A <- IP protocol */
55 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_UDP, 1, 0), /* IP protocol == UDP ? */
56 BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
57 BPF_STMT(BPF_LD + BPF_B + BPF_ABS, offsetof(DHCPPacket, ip.frag_off)), /* A <- Flags */
58 BPF_STMT(BPF_ALU + BPF_AND + BPF_K, 0x20), /* A <- A & 0x20 (More Fragments bit) */
59 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0, 1, 0), /* A == 0 ? */
60 BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
61 BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(DHCPPacket, ip.frag_off)), /* A <- Flags + Fragment offset */
62 BPF_STMT(BPF_ALU + BPF_AND + BPF_K, 0x1fff), /* A <- A & 0x1fff (Fragment offset) */
63 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0, 1, 0), /* A == 0 ? */
64 BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
65 BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(DHCPPacket, udp.dest)), /* A <- UDP destination port */
9faed222 66 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, port, 1, 0), /* UDP destination port == DHCP client port ? */
088b6ba2
LP
67 BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
68 BPF_STMT(BPF_LD + BPF_B + BPF_ABS, offsetof(DHCPPacket, dhcp.op)), /* A <- DHCP op */
69 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, BOOTREPLY, 1, 0), /* op == BOOTREPLY ? */
70 BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
71 BPF_STMT(BPF_LD + BPF_B + BPF_ABS, offsetof(DHCPPacket, dhcp.htype)), /* A <- DHCP header type */
76253e73 72 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, arp_type, 1, 0), /* header type == arp_type ? */
088b6ba2 73 BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
088b6ba2
LP
74 BPF_STMT(BPF_LD + BPF_W + BPF_ABS, offsetof(DHCPPacket, dhcp.xid)), /* A <- client identifier */
75 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, xid, 1, 0), /* client identifier == xid ? */
76 BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
13f1fd03 77 BPF_STMT(BPF_LD + BPF_B + BPF_ABS, offsetof(DHCPPacket, dhcp.hlen)), /* A <- MAC address length */
073a1daa 78 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, (uint8_t) hw_addr->length, 1, 0), /* address length == hw_addr->length ? */
13f1fd03
TH
79 BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
80
81 /* We only support MAC address length to be either 0 or 6 (ETH_ALEN). Optionally
82 * compare chaddr for ETH_ALEN bytes. */
073a1daa
YW
83 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETH_ALEN, 0, 8), /* A (the MAC address length) == ETH_ALEN ? */
84 BPF_STMT(BPF_LDX + BPF_IMM, unaligned_read_be32(hw_addr->bytes)), /* X <- 4 bytes of client's MAC */
85 BPF_STMT(BPF_LD + BPF_W + BPF_ABS, offsetof(DHCPPacket, dhcp.chaddr)), /* A <- 4 bytes of MAC from dhcp.chaddr */
86 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_X, 0, 1, 0), /* A == X ? */
87 BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
88 BPF_STMT(BPF_LDX + BPF_IMM, unaligned_read_be16(hw_addr->bytes + 4)), /* X <- remainder of client's MAC */
89 BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(DHCPPacket, dhcp.chaddr) + 4), /* A <- remainder of MAC from dhcp.chaddr */
90 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_X, 0, 1, 0), /* A == X ? */
91 BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
13f1fd03 92
088b6ba2
LP
93 BPF_STMT(BPF_LD + BPF_W + BPF_ABS, offsetof(DHCPPacket, dhcp.magic)), /* A <- DHCP magic cookie */
94 BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, DHCP_MAGIC_COOKIE, 1, 0), /* cookie == DHCP magic cookie ? */
95 BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
ea51deb1 96 BPF_STMT(BPF_RET + BPF_K, UINT32_MAX), /* accept */
bc29e507
TG
97 };
98 struct sock_fprog fprog = {
088b6ba2
LP
99 .len = ELEMENTSOF(filter),
100 .filter = filter
bc29e507 101 };
5bb1d7fb 102 _cleanup_close_ int s = -EBADF;
6d5e65f6 103 int r;
8b4a9693 104
66a67eff 105 s = socket(AF_PACKET, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0);
8b4a9693
PF
106 if (s < 0)
107 return -errno;
108
2ff48e98 109 r = setsockopt_int(s, SOL_PACKET, PACKET_AUXDATA, true);
c3d2994b 110 if (r < 0)
2ff48e98 111 return r;
c3d2994b
TG
112
113 r = setsockopt(s, SOL_SOCKET, SO_ATTACH_FILTER, &fprog, sizeof(fprog));
114 if (r < 0)
115 return -errno;
116
905d0ea7
YW
117 r = setsockopt_int(s, SOL_SOCKET, SO_TIMESTAMP, true);
118 if (r < 0)
119 return r;
120
ea577968 121 if (so_priority_set) {
122 r = setsockopt_int(s, SOL_SOCKET, SO_PRIORITY, so_priority);
123 if (r < 0)
124 return r;
125 }
126
b1f24b75
BG
127 link->ll = (struct sockaddr_ll) {
128 .sll_family = AF_PACKET,
129 .sll_protocol = htobe16(ETH_P_IP),
130 .sll_ifindex = ifindex,
131 .sll_hatype = htobe16(arp_type),
073a1daa 132 .sll_halen = bcast_addr->length,
b1f24b75 133 };
073a1daa
YW
134 /* We may overflow link->ll. link->ll_buffer ensures we have enough space. */
135 memcpy(link->ll.sll_addr, bcast_addr->bytes, bcast_addr->length);
8b4a9693 136
a0233fcd 137 r = bind(s, &link->sa, sockaddr_ll_len(&link->ll));
c3d2994b 138 if (r < 0)
bc29e507 139 return -errno;
bc29e507 140
c10d6bdb 141 return TAKE_FD(s);
8c00042c
PF
142}
143
155943b2
YW
144int dhcp_network_bind_raw_socket(
145 int ifindex,
146 union sockaddr_union *link,
147 uint32_t xid,
073a1daa
YW
148 const struct hw_addr_data *hw_addr,
149 const struct hw_addr_data *bcast_addr,
155943b2 150 uint16_t arp_type,
ea577968 151 uint16_t port,
152 bool so_priority_set,
153 int so_priority) {
155943b2 154
073a1daa
YW
155 static struct hw_addr_data default_eth_bcast = {
156 .length = ETH_ALEN,
157 .ether = {{ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff }},
158 }, default_ib_bcast = {
159 .length = INFINIBAND_ALEN,
160 .infiniband = {
161 0x00, 0xff, 0xff, 0xff, 0xff, 0x12, 0x40, 0x1b,
162 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
163 0xff, 0xff, 0xff, 0xff
164 },
14b66dbc 165 };
76253e73 166
073a1daa
YW
167 assert(ifindex > 0);
168 assert(link);
169 assert(hw_addr);
170
171 switch (arp_type) {
172 case ARPHRD_ETHER:
173 return _bind_raw_socket(ifindex, link, xid,
174 hw_addr,
175 (bcast_addr && !hw_addr_is_null(bcast_addr)) ? bcast_addr : &default_eth_bcast,
ea577968 176 arp_type, port, so_priority_set, so_priority);
073a1daa
YW
177
178 case ARPHRD_INFINIBAND:
179 return _bind_raw_socket(ifindex, link, xid,
180 &HW_ADDR_NULL,
181 (bcast_addr && !hw_addr_is_null(bcast_addr)) ? bcast_addr : &default_ib_bcast,
ea577968 182 arp_type, port, so_priority_set, so_priority);
073a1daa
YW
183 default:
184 return -EINVAL;
14b66dbc 185 }
76253e73
DW
186}
187
afe42aef 188int dhcp_network_bind_udp_socket(int ifindex, be32_t address, uint16_t port, int ip_service_type) {
234fc2df
PF
189 union sockaddr_union src = {
190 .in.sin_family = AF_INET,
080ab276
TG
191 .in.sin_port = htobe16(port),
192 .in.sin_addr.s_addr = address,
234fc2df 193 };
5bb1d7fb 194 _cleanup_close_ int s = -EBADF;
9e5b6496 195 int r;
234fc2df
PF
196
197 s = socket(AF_INET, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0);
198 if (s < 0)
199 return -errno;
200
afe42aef
SC
201 if (ip_service_type >= 0)
202 r = setsockopt_int(s, IPPROTO_IP, IP_TOS, ip_service_type);
203 else
204 r = setsockopt_int(s, IPPROTO_IP, IP_TOS, IPTOS_CLASS_CS6);
c3d2994b 205 if (r < 0)
9e5b6496 206 return r;
b44cd882 207
2ff48e98 208 r = setsockopt_int(s, SOL_SOCKET, SO_REUSEADDR, true);
076adf01 209 if (r < 0)
2ff48e98 210 return r;
fef0e0f3 211
905d0ea7
YW
212 r = setsockopt_int(s, SOL_SOCKET, SO_TIMESTAMP, true);
213 if (r < 0)
214 return r;
215
3e7b9f76 216 if (ifindex > 0) {
953a02d1 217 r = socket_bind_to_ifindex(s, ifindex);
3e7b9f76 218 if (r < 0)
953a02d1 219 return r;
3e7b9f76
MK
220 }
221
21b6b87e 222 if (port == DHCP_PORT_SERVER) {
2ff48e98 223 r = setsockopt_int(s, SOL_SOCKET, SO_BROADCAST, true);
d6bd972d 224 if (r < 0)
2ff48e98 225 return r;
21b6b87e
YA
226 if (address == INADDR_ANY) {
227 /* IP_PKTINFO filter should not be applied when packets are
228 allowed to enter/leave through the interface other than
229 DHCP server sits on(BindToInterface option). */
230 r = setsockopt_int(s, IPPROTO_IP, IP_PKTINFO, true);
231 if (r < 0)
232 return r;
233 }
076adf01 234 } else {
2ff48e98 235 r = setsockopt_int(s, IPPROTO_IP, IP_FREEBIND, true);
076adf01 236 if (r < 0)
2ff48e98 237 return r;
fef0e0f3 238 }
85923f79 239
d70c7813 240 if (bind(s, &src.sa, sizeof(src.in)) < 0)
234fc2df 241 return -errno;
234fc2df 242
c10d6bdb 243 return TAKE_FD(s);
234fc2df
PF
244}
245
155943b2
YW
246int dhcp_network_send_raw_socket(
247 int s,
248 const union sockaddr_union *link,
249 const void *packet,
250 size_t len) {
c3d2994b 251
b8319d74
YW
252 /* Do not add assert(s >= 0) here, as this is called in fuzz-dhcp-server, and in that case this
253 * function should fail with negative errno. */
254
23f30ed3
TG
255 assert(link);
256 assert(packet);
b8319d74 257 assert(len > 0);
23f30ed3 258
a0233fcd 259 if (sendto(s, packet, len, 0, &link->sa, sockaddr_ll_len(&link->ll)) < 0)
1c8035a8 260 return -errno;
8b4a9693 261
1c8035a8 262 return 0;
8b4a9693 263}
234fc2df 264
155943b2
YW
265int dhcp_network_send_udp_socket(
266 int s,
267 be32_t address,
268 uint16_t port,
269 const void *packet,
270 size_t len) {
271
234fc2df
PF
272 union sockaddr_union dest = {
273 .in.sin_family = AF_INET,
080ab276
TG
274 .in.sin_port = htobe16(port),
275 .in.sin_addr.s_addr = address,
234fc2df 276 };
c3d2994b
TG
277
278 assert(s >= 0);
279 assert(packet);
b8319d74 280 assert(len > 0);
234fc2df 281
d70c7813 282 if (sendto(s, packet, len, 0, &dest.sa, sizeof(dest.in)) < 0)
234fc2df
PF
283 return -errno;
284
285 return 0;
286}