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git.ipfire.org Git - thirdparty/systemd.git/blob - src/libsystemd-network/dhcp-network.c
1 /* SPDX-License-Identifier: LGPL-2.1+ */
3 Copyright (C) 2013 Intel Corporation. All rights reserved.
7 #include <net/ethernet.h>
9 #include <net/if_arp.h>
12 #include <sys/socket.h>
13 #include <linux/filter.h>
14 #include <linux/if_infiniband.h>
15 #include <linux/if_packet.h>
17 #include "dhcp-internal.h"
19 #include "socket-util.h"
20 #include "unaligned.h"
22 static int _bind_raw_socket(int ifindex
, union sockaddr_union
*link
,
23 uint32_t xid
, const uint8_t *mac_addr
,
25 const uint8_t *bcast_addr
,
26 const struct ether_addr
*eth_mac
,
27 uint16_t arp_type
, uint8_t dhcp_hlen
,
29 struct sock_filter filter
[] = {
30 BPF_STMT(BPF_LD
+ BPF_W
+ BPF_LEN
, 0), /* A <- packet length */
31 BPF_JUMP(BPF_JMP
+ BPF_JGE
+ BPF_K
, sizeof(DHCPPacket
), 1, 0), /* packet >= DHCPPacket ? */
32 BPF_STMT(BPF_RET
+ BPF_K
, 0), /* ignore */
33 BPF_STMT(BPF_LD
+ BPF_B
+ BPF_ABS
, offsetof(DHCPPacket
, ip
.protocol
)), /* A <- IP protocol */
34 BPF_JUMP(BPF_JMP
+ BPF_JEQ
+ BPF_K
, IPPROTO_UDP
, 1, 0), /* IP protocol == UDP ? */
35 BPF_STMT(BPF_RET
+ BPF_K
, 0), /* ignore */
36 BPF_STMT(BPF_LD
+ BPF_B
+ BPF_ABS
, offsetof(DHCPPacket
, ip
.frag_off
)), /* A <- Flags */
37 BPF_STMT(BPF_ALU
+ BPF_AND
+ BPF_K
, 0x20), /* A <- A & 0x20 (More Fragments bit) */
38 BPF_JUMP(BPF_JMP
+ BPF_JEQ
+ BPF_K
, 0, 1, 0), /* A == 0 ? */
39 BPF_STMT(BPF_RET
+ BPF_K
, 0), /* ignore */
40 BPF_STMT(BPF_LD
+ BPF_H
+ BPF_ABS
, offsetof(DHCPPacket
, ip
.frag_off
)), /* A <- Flags + Fragment offset */
41 BPF_STMT(BPF_ALU
+ BPF_AND
+ BPF_K
, 0x1fff), /* A <- A & 0x1fff (Fragment offset) */
42 BPF_JUMP(BPF_JMP
+ BPF_JEQ
+ BPF_K
, 0, 1, 0), /* A == 0 ? */
43 BPF_STMT(BPF_RET
+ BPF_K
, 0), /* ignore */
44 BPF_STMT(BPF_LD
+ BPF_H
+ BPF_ABS
, offsetof(DHCPPacket
, udp
.dest
)), /* A <- UDP destination port */
45 BPF_JUMP(BPF_JMP
+ BPF_JEQ
+ BPF_K
, port
, 1, 0), /* UDP destination port == DHCP client port ? */
46 BPF_STMT(BPF_RET
+ BPF_K
, 0), /* ignore */
47 BPF_STMT(BPF_LD
+ BPF_B
+ BPF_ABS
, offsetof(DHCPPacket
, dhcp
.op
)), /* A <- DHCP op */
48 BPF_JUMP(BPF_JMP
+ BPF_JEQ
+ BPF_K
, BOOTREPLY
, 1, 0), /* op == BOOTREPLY ? */
49 BPF_STMT(BPF_RET
+ BPF_K
, 0), /* ignore */
50 BPF_STMT(BPF_LD
+ BPF_B
+ BPF_ABS
, offsetof(DHCPPacket
, dhcp
.htype
)), /* A <- DHCP header type */
51 BPF_JUMP(BPF_JMP
+ BPF_JEQ
+ BPF_K
, arp_type
, 1, 0), /* header type == arp_type ? */
52 BPF_STMT(BPF_RET
+ BPF_K
, 0), /* ignore */
53 BPF_STMT(BPF_LD
+ BPF_B
+ BPF_ABS
, offsetof(DHCPPacket
, dhcp
.hlen
)), /* A <- MAC address length */
54 BPF_JUMP(BPF_JMP
+ BPF_JEQ
+ BPF_K
, dhcp_hlen
, 1, 0), /* address length == dhcp_hlen ? */
55 BPF_STMT(BPF_RET
+ BPF_K
, 0), /* ignore */
56 BPF_STMT(BPF_LD
+ BPF_W
+ BPF_ABS
, offsetof(DHCPPacket
, dhcp
.xid
)), /* A <- client identifier */
57 BPF_JUMP(BPF_JMP
+ BPF_JEQ
+ BPF_K
, xid
, 1, 0), /* client identifier == xid ? */
58 BPF_STMT(BPF_RET
+ BPF_K
, 0), /* ignore */
59 BPF_STMT(BPF_LD
+ BPF_IMM
, unaligned_read_be32(ð_mac
->ether_addr_octet
[0])), /* A <- 4 bytes of client's MAC */
60 BPF_STMT(BPF_MISC
+ BPF_TAX
, 0), /* X <- A */
61 BPF_STMT(BPF_LD
+ BPF_W
+ BPF_ABS
, offsetof(DHCPPacket
, dhcp
.chaddr
)), /* A <- 4 bytes of MAC from dhcp.chaddr */
62 BPF_STMT(BPF_ALU
+ BPF_XOR
+ BPF_X
, 0), /* A xor X */
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_IMM
, unaligned_read_be16(ð_mac
->ether_addr_octet
[4])), /* A <- remainder of client's MAC */
66 BPF_STMT(BPF_MISC
+ BPF_TAX
, 0), /* X <- A */
67 BPF_STMT(BPF_LD
+ BPF_H
+ BPF_ABS
, offsetof(DHCPPacket
, dhcp
.chaddr
) + 4), /* A <- remainder of MAC from dhcp.chaddr */
68 BPF_STMT(BPF_ALU
+ BPF_XOR
+ BPF_X
, 0), /* A xor X */
69 BPF_JUMP(BPF_JMP
+ BPF_JEQ
+ BPF_K
, 0, 1, 0), /* A == 0 ? */
70 BPF_STMT(BPF_RET
+ BPF_K
, 0), /* ignore */
71 BPF_STMT(BPF_LD
+ BPF_W
+ BPF_ABS
, offsetof(DHCPPacket
, dhcp
.magic
)), /* A <- DHCP magic cookie */
72 BPF_JUMP(BPF_JMP
+ BPF_JEQ
+ BPF_K
, DHCP_MAGIC_COOKIE
, 1, 0), /* cookie == DHCP magic cookie ? */
73 BPF_STMT(BPF_RET
+ BPF_K
, 0), /* ignore */
74 BPF_STMT(BPF_RET
+ BPF_K
, 65535), /* return all */
76 struct sock_fprog fprog
= {
77 .len
= ELEMENTSOF(filter
),
80 _cleanup_close_
int s
= -1;
86 s
= socket(AF_PACKET
, SOCK_DGRAM
| SOCK_CLOEXEC
| SOCK_NONBLOCK
, 0);
90 r
= setsockopt(s
, SOL_PACKET
, PACKET_AUXDATA
, &on
, sizeof(on
));
94 r
= setsockopt(s
, SOL_SOCKET
, SO_ATTACH_FILTER
, &fprog
, sizeof(fprog
));
98 link
->ll
= (struct sockaddr_ll
) {
99 .sll_family
= AF_PACKET
,
100 .sll_protocol
= htobe16(ETH_P_IP
),
101 .sll_ifindex
= ifindex
,
102 .sll_hatype
= htobe16(arp_type
),
103 .sll_halen
= mac_addr_len
,
105 memcpy(link
->ll
.sll_addr
, bcast_addr
, mac_addr_len
);
107 r
= bind(s
, &link
->sa
, SOCKADDR_LL_LEN(link
->ll
));
114 int dhcp_network_bind_raw_socket(int ifindex
, union sockaddr_union
*link
,
115 uint32_t xid
, const uint8_t *mac_addr
,
116 size_t mac_addr_len
, uint16_t arp_type
,
118 static const uint8_t eth_bcast
[] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
119 /* Default broadcast address for IPoIB */
120 static const uint8_t ib_bcast
[] = {
121 0x00, 0xff, 0xff, 0xff, 0xff, 0x12, 0x40, 0x1b,
122 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
123 0xff, 0xff, 0xff, 0xff
125 struct ether_addr eth_mac
= { { 0, 0, 0, 0, 0, 0 } };
126 const uint8_t *bcast_addr
= NULL
;
127 uint8_t dhcp_hlen
= 0;
129 assert_return(mac_addr_len
> 0, -EINVAL
);
131 if (arp_type
== ARPHRD_ETHER
) {
132 assert_return(mac_addr_len
== ETH_ALEN
, -EINVAL
);
133 memcpy(ð_mac
, mac_addr
, ETH_ALEN
);
134 bcast_addr
= eth_bcast
;
135 dhcp_hlen
= ETH_ALEN
;
136 } else if (arp_type
== ARPHRD_INFINIBAND
) {
137 assert_return(mac_addr_len
== INFINIBAND_ALEN
, -EINVAL
);
138 bcast_addr
= ib_bcast
;
142 return _bind_raw_socket(ifindex
, link
, xid
, mac_addr
, mac_addr_len
,
143 bcast_addr
, ð_mac
, arp_type
, dhcp_hlen
, port
);
146 int dhcp_network_bind_udp_socket(int ifindex
, be32_t address
, uint16_t port
) {
147 union sockaddr_union src
= {
148 .in
.sin_family
= AF_INET
,
149 .in
.sin_port
= htobe16(port
),
150 .in
.sin_addr
.s_addr
= address
,
152 _cleanup_close_
int s
= -1;
153 char ifname
[IF_NAMESIZE
] = "";
154 int r
, on
= 1, tos
= IPTOS_CLASS_CS6
;
156 s
= socket(AF_INET
, SOCK_DGRAM
| SOCK_CLOEXEC
| SOCK_NONBLOCK
, 0);
160 r
= setsockopt(s
, IPPROTO_IP
, IP_TOS
, &tos
, sizeof(tos
));
164 r
= setsockopt(s
, SOL_SOCKET
, SO_REUSEADDR
, &on
, sizeof(on
));
169 if (if_indextoname(ifindex
, ifname
) == 0)
172 r
= setsockopt(s
, SOL_SOCKET
, SO_BINDTODEVICE
, ifname
, strlen(ifname
));
177 if (address
== INADDR_ANY
) {
178 r
= setsockopt(s
, IPPROTO_IP
, IP_PKTINFO
, &on
, sizeof(on
));
182 r
= setsockopt(s
, SOL_SOCKET
, SO_BROADCAST
, &on
, sizeof(on
));
187 r
= setsockopt(s
, IPPROTO_IP
, IP_FREEBIND
, &on
, sizeof(on
));
192 r
= bind(s
, &src
.sa
, sizeof(src
.in
));
199 int dhcp_network_send_raw_socket(int s
, const union sockaddr_union
*link
,
200 const void *packet
, size_t len
) {
207 r
= sendto(s
, packet
, len
, 0, &link
->sa
, SOCKADDR_LL_LEN(link
->ll
));
214 int dhcp_network_send_udp_socket(int s
, be32_t address
, uint16_t port
,
215 const void *packet
, size_t len
) {
216 union sockaddr_union dest
= {
217 .in
.sin_family
= AF_INET
,
218 .in
.sin_port
= htobe16(port
),
219 .in
.sin_addr
.s_addr
= address
,
227 r
= sendto(s
, packet
, len
, 0, &dest
.sa
, sizeof(dest
.in
));