1 /*
2 * dhcpcd - DHCP client daemon
3 * Copyright (c) 2006-2008 Roy Marples <roy@marples.name>
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27 #include <sys/types.h>
28 #include <sys/ioctl.h>
29 #include <sys/socket.h>
30 #include <sys/uio.h>
31
32 #include <net/bpf.h>
33 #include <net/if.h>
34 #include <arpa/inet.h>
35
36 #include <errno.h>
37 #include <fcntl.h>
38 #include <paths.h>
39 #include <stdio.h>
40 #include <stdlib.h>
41 #include <string.h>
42 #include <unistd.h>
43
44 #include "common.h"
45 #include "dhcp.h"
46 #include "net.h"
47 #include "bpf-filter.h"
48
49 #include <rump/rump.h>
50 #include <rump/rump_syscalls.h>
51
52 int
open_socket(struct interface * iface,int protocol)53 open_socket(struct interface *iface, int protocol)
54 {
55 int fd = -1;
56 int *fdp = NULL;
57 struct ifreq ifr;
58 int buf_len = 0;
59 struct bpf_version pv;
60 struct bpf_program pf;
61 #ifdef BIOCIMMEDIATE
62 int flags;
63 #endif
64 #ifdef _PATH_BPF
65 fd = rump_sys_open(_PATH_BPF, O_RDWR | O_NONBLOCK);
66 #else
67 char *device;
68 int n = 0;
69
70 device = xmalloc(sizeof(char) * PATH_MAX);
71 do {
72 snprintf(device, PATH_MAX, "/dev/bpf%d", n++);
73 fd = rump_sys_open(device, O_RDWR | O_NONBLOCK);
74 } while (fd == -1 && errno == EBUSY);
75 free(device);
76 #endif
77
78 if (fd == -1)
79 return -1;
80
81 if (rump_sys_ioctl(fd, BIOCVERSION, &pv) == -1)
82 goto eexit;
83 if (pv.bv_major != BPF_MAJOR_VERSION ||
84 pv.bv_minor < BPF_MINOR_VERSION) {
85 fprintf(stderr, "BPF version mismatch - recompile");
86 goto eexit;
87 }
88
89 memset(&ifr, 0, sizeof(ifr));
90 strlcpy(ifr.ifr_name, iface->name, sizeof(ifr.ifr_name));
91 if (rump_sys_ioctl(fd, BIOCSETIF, &ifr) == -1)
92 goto eexit;
93
94 /* Get the required BPF buffer length from the kernel. */
95 if (rump_sys_ioctl(fd, BIOCGBLEN, &buf_len) == -1)
96 goto eexit;
97 if (iface->buffer_size != (size_t)buf_len) {
98 free(iface->buffer);
99 iface->buffer_size = buf_len;
100 iface->buffer = xmalloc(buf_len);
101 iface->buffer_len = iface->buffer_pos = 0;
102 }
103
104 #ifdef BIOCIMMEDIATE
105 flags = 1;
106 if (rump_sys_ioctl(fd, BIOCIMMEDIATE, &flags) == -1)
107 goto eexit;
108 #endif
109
110 /* Install the DHCP filter */
111 if (protocol == ETHERTYPE_ARP) {
112 pf.bf_insns = UNCONST(arp_bpf_filter);
113 pf.bf_len = arp_bpf_filter_len;
114 fdp = &iface->arp_fd;
115 } else {
116 pf.bf_insns = UNCONST(dhcp_bpf_filter);
117 pf.bf_len = dhcp_bpf_filter_len;
118 fdp = &iface->raw_fd;
119 }
120 if (rump_sys_ioctl(fd, BIOCSETF, &pf) == -1)
121 goto eexit;
122 if (fdp) {
123 if (*fdp != -1)
124 rump_sys_close(*fdp);
125 *fdp = fd;
126 }
127 return fd;
128
129 eexit:
130 free(iface->buffer);
131 iface->buffer = NULL;
132 rump_sys_close(fd);
133 return -1;
134 }
135
136 ssize_t
send_raw_packet(const struct interface * iface,int protocol,const void * data,ssize_t len)137 send_raw_packet(const struct interface *iface, int protocol,
138 const void *data, ssize_t len)
139 {
140 struct iovec iov[2];
141 struct ether_header hw;
142 int fd;
143
144 memset(&hw, 0, ETHER_HDR_LEN);
145 memset(&hw.ether_dhost, 0xff, ETHER_ADDR_LEN);
146 hw.ether_type = htons(protocol);
147 iov[0].iov_base = &hw;
148 iov[0].iov_len = ETHER_HDR_LEN;
149 iov[1].iov_base = UNCONST(data);
150 iov[1].iov_len = len;
151 if (protocol == ETHERTYPE_ARP)
152 fd = iface->arp_fd;
153 else
154 fd = iface->raw_fd;
155 return rump_sys_writev(fd, iov, 2);
156 }
157
158 /* BPF requires that we read the entire buffer.
159 * So we pass the buffer in the API so we can loop on >1 packet. */
160 ssize_t
get_raw_packet(struct interface * iface,int protocol,void * data,ssize_t len)161 get_raw_packet(struct interface *iface, int protocol,
162 void *data, ssize_t len)
163 {
164 int fd = -1;
165 struct bpf_hdr packet;
166 ssize_t bytes;
167 const unsigned char *payload;
168
169 if (protocol == ETHERTYPE_ARP)
170 fd = iface->arp_fd;
171 else
172 fd = iface->raw_fd;
173
174 for (;;) {
175 if (iface->buffer_len == 0) {
176 bytes = rump_sys_read(fd, iface->buffer, iface->buffer_size);
177 if (bytes == -1)
178 return errno == EAGAIN ? 0 : -1;
179 else if ((size_t)bytes < sizeof(packet))
180 return -1;
181 iface->buffer_len = bytes;
182 iface->buffer_pos = 0;
183 }
184 bytes = -1;
185 memcpy(&packet, iface->buffer + iface->buffer_pos,
186 sizeof(packet));
187 if (packet.bh_caplen != packet.bh_datalen)
188 goto next; /* Incomplete packet, drop. */
189 if (iface->buffer_pos + packet.bh_caplen + packet.bh_hdrlen >
190 iface->buffer_len)
191 goto next; /* Packet beyond buffer, drop. */
192 payload = iface->buffer + packet.bh_hdrlen + ETHER_HDR_LEN;
193 bytes = packet.bh_caplen - ETHER_HDR_LEN;
194 if (bytes > len)
195 bytes = len;
196 memcpy(data, payload, bytes);
197 next:
198 iface->buffer_pos += BPF_WORDALIGN(packet.bh_hdrlen +
199 packet.bh_caplen);
200 if (iface->buffer_pos >= iface->buffer_len)
201 iface->buffer_len = iface->buffer_pos = 0;
202 if (bytes != -1)
203 return bytes;
204 }
205 }
206