1 /*
2  * WPA Supplicant - Layer2 packet handling with FreeBSD
3  * Copyright (c) 2003-2005, Jouni Malinen <j@w1.fi>
4  * Copyright (c) 2005, Sam Leffler <sam@errno.com>
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License version 2 as
8  * published by the Free Software Foundation.
9  *
10  * Alternatively, this software may be distributed under the terms of BSD
11  * license.
12  *
13  * See README and COPYING for more details.
14  */
15 
16 #include "includes.h"
17 #ifdef __APPLE__
18 #include <net/bpf.h>
19 #endif /* __APPLE__ */
20 #include <pcap.h>
21 
22 #include <sys/ioctl.h>
23 #include <sys/sysctl.h>
24 
25 #include <net/if.h>
26 #include <net/if_dl.h>
27 #include <net/route.h>
28 #include <netinet/in.h>
29 
30 #include "common.h"
31 #include "eloop.h"
32 #include "l2_packet.h"
33 
34 
35 static const u8 pae_group_addr[ETH_ALEN] =
36 { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x03 };
37 
38 struct l2_packet_data {
39 	pcap_t *pcap;
40 	char ifname[100];
41 	u8 own_addr[ETH_ALEN];
42 	void (*rx_callback)(void *ctx, const u8 *src_addr,
43 			    const u8 *buf, size_t len);
44 	void *rx_callback_ctx;
45 	int l2_hdr; /* whether to include layer 2 (Ethernet) header data
46 		     * buffers */
47 };
48 
49 
50 int l2_packet_get_own_addr(struct l2_packet_data *l2, u8 *addr)
51 {
52 	os_memcpy(addr, l2->own_addr, ETH_ALEN);
53 	return 0;
54 }
55 
56 
57 int l2_packet_send(struct l2_packet_data *l2, const u8 *dst_addr, u16 proto,
58 		   const u8 *buf, size_t len)
59 {
60 	if (!l2->l2_hdr) {
61 		int ret;
62 		struct l2_ethhdr *eth = os_malloc(sizeof(*eth) + len);
63 		if (eth == NULL)
64 			return -1;
65 		os_memcpy(eth->h_dest, dst_addr, ETH_ALEN);
66 		os_memcpy(eth->h_source, l2->own_addr, ETH_ALEN);
67 		eth->h_proto = htons(proto);
68 		os_memcpy(eth + 1, buf, len);
69 		ret = pcap_inject(l2->pcap, (u8 *) eth, len + sizeof(*eth));
70 		os_free(eth);
71 		return ret;
72 	} else
73 		return pcap_inject(l2->pcap, buf, len);
74 }
75 
76 
77 static void l2_packet_receive(int sock, void *eloop_ctx, void *sock_ctx)
78 {
79 	struct l2_packet_data *l2 = eloop_ctx;
80 	pcap_t *pcap = sock_ctx;
81 	struct pcap_pkthdr hdr;
82 	const u_char *packet;
83 	struct l2_ethhdr *ethhdr;
84 	unsigned char *buf;
85 	size_t len;
86 
87 	packet = pcap_next(pcap, &hdr);
88 
89 	if (packet == NULL || hdr.caplen < sizeof(*ethhdr))
90 		return;
91 
92 	ethhdr = (struct l2_ethhdr *) packet;
93 	if (l2->l2_hdr) {
94 		buf = (unsigned char *) ethhdr;
95 		len = hdr.caplen;
96 	} else {
97 		buf = (unsigned char *) (ethhdr + 1);
98 		len = hdr.caplen - sizeof(*ethhdr);
99 	}
100 	l2->rx_callback(l2->rx_callback_ctx, ethhdr->h_source, buf, len);
101 }
102 
103 
104 static int l2_packet_init_libpcap(struct l2_packet_data *l2,
105 				  unsigned short protocol)
106 {
107 	bpf_u_int32 pcap_maskp, pcap_netp;
108 	char pcap_filter[200], pcap_err[PCAP_ERRBUF_SIZE];
109 	struct bpf_program pcap_fp;
110 
111 	pcap_lookupnet(l2->ifname, &pcap_netp, &pcap_maskp, pcap_err);
112 	l2->pcap = pcap_open_live(l2->ifname, 2500, 0, 10, pcap_err);
113 	if (l2->pcap == NULL) {
114 		fprintf(stderr, "pcap_open_live: %s\n", pcap_err);
115 		fprintf(stderr, "ifname='%s'\n", l2->ifname);
116 		return -1;
117 	}
118 	if (pcap_datalink(l2->pcap) != DLT_EN10MB &&
119 	    pcap_set_datalink(l2->pcap, DLT_EN10MB) < 0) {
120 		fprintf(stderr, "pcap_set_datalink(DLT_EN10MB): %s\n",
121 			pcap_geterr(l2->pcap));
122 		return -1;
123 	}
124 	os_snprintf(pcap_filter, sizeof(pcap_filter),
125 		    "not ether src " MACSTR " and "
126 		    "( ether dst " MACSTR " or ether dst " MACSTR " ) and "
127 		    "ether proto 0x%x",
128 		    MAC2STR(l2->own_addr), /* do not receive own packets */
129 		    MAC2STR(l2->own_addr), MAC2STR(pae_group_addr),
130 		    protocol);
131 	if (pcap_compile(l2->pcap, &pcap_fp, pcap_filter, 1, pcap_netp) < 0) {
132 		fprintf(stderr, "pcap_compile: %s\n", pcap_geterr(l2->pcap));
133 		return -1;
134 	}
135 
136 	if (pcap_setfilter(l2->pcap, &pcap_fp) < 0) {
137 		fprintf(stderr, "pcap_setfilter: %s\n", pcap_geterr(l2->pcap));
138 		return -1;
139 	}
140 
141 	pcap_freecode(&pcap_fp);
142 	/*
143 	 * When libpcap uses BPF we must enable "immediate mode" to
144 	 * receive frames right away; otherwise the system may
145 	 * buffer them for us.
146 	 */
147 	{
148 		unsigned int on = 1;
149 		if (ioctl(pcap_fileno(l2->pcap), BIOCIMMEDIATE, &on) < 0) {
150 			fprintf(stderr, "%s: cannot enable immediate mode on "
151 				"interface %s: %s\n",
152 				__func__, l2->ifname, strerror(errno));
153 			/* XXX should we fail? */
154 		}
155 	}
156 
157 	eloop_register_read_sock(pcap_get_selectable_fd(l2->pcap),
158 				 l2_packet_receive, l2, l2->pcap);
159 
160 	return 0;
161 }
162 
163 
164 static int eth_get(const char *device, u8 ea[ETH_ALEN])
165 {
166 	struct if_msghdr *ifm;
167 	struct sockaddr_dl *sdl;
168 	u_char *p, *buf;
169 	size_t len;
170 	int mib[] = { CTL_NET, AF_ROUTE, 0, AF_LINK, NET_RT_IFLIST, 0 };
171 
172 	if (sysctl(mib, 6, NULL, &len, NULL, 0) < 0)
173 		return -1;
174 	if ((buf = os_malloc(len)) == NULL)
175 		return -1;
176 	if (sysctl(mib, 6, buf, &len, NULL, 0) < 0) {
177 		os_free(buf);
178 		return -1;
179 	}
180 	for (p = buf; p < buf + len; p += ifm->ifm_msglen) {
181 		ifm = (struct if_msghdr *)p;
182 		sdl = (struct sockaddr_dl *)(ifm + 1);
183 		if (ifm->ifm_type != RTM_IFINFO ||
184 		    (ifm->ifm_addrs & RTA_IFP) == 0)
185 			continue;
186 		if (sdl->sdl_family != AF_LINK || sdl->sdl_nlen == 0 ||
187 		    os_memcmp(sdl->sdl_data, device, sdl->sdl_nlen) != 0)
188 			continue;
189 		os_memcpy(ea, LLADDR(sdl), sdl->sdl_alen);
190 		break;
191 	}
192 	os_free(buf);
193 
194 	if (p >= buf + len) {
195 		errno = ESRCH;
196 		return -1;
197 	}
198 	return 0;
199 }
200 
201 
202 struct l2_packet_data * l2_packet_init(
203 	const char *ifname, const u8 *own_addr, unsigned short protocol,
204 	void (*rx_callback)(void *ctx, const u8 *src_addr,
205 			    const u8 *buf, size_t len),
206 	void *rx_callback_ctx, int l2_hdr)
207 {
208 	struct l2_packet_data *l2;
209 
210 	l2 = os_zalloc(sizeof(struct l2_packet_data));
211 	if (l2 == NULL)
212 		return NULL;
213 	os_strlcpy(l2->ifname, ifname, sizeof(l2->ifname));
214 	l2->rx_callback = rx_callback;
215 	l2->rx_callback_ctx = rx_callback_ctx;
216 	l2->l2_hdr = l2_hdr;
217 
218 	if (eth_get(l2->ifname, l2->own_addr) < 0) {
219 		fprintf(stderr, "Failed to get link-level address for "
220 			"interface '%s'.\n", l2->ifname);
221 		os_free(l2);
222 		return NULL;
223 	}
224 
225 	if (l2_packet_init_libpcap(l2, protocol)) {
226 		os_free(l2);
227 		return NULL;
228 	}
229 
230 	return l2;
231 }
232 
233 
234 void l2_packet_deinit(struct l2_packet_data *l2)
235 {
236 	if (l2 != NULL) {
237 		if (l2->pcap) {
238 			eloop_unregister_read_sock(
239 				pcap_get_selectable_fd(l2->pcap));
240 			pcap_close(l2->pcap);
241 		}
242 		os_free(l2);
243 	}
244 }
245 
246 
247 int l2_packet_get_ip_addr(struct l2_packet_data *l2, char *buf, size_t len)
248 {
249 	pcap_if_t *devs, *dev;
250 	struct pcap_addr *addr;
251 	struct sockaddr_in *saddr;
252 	int found = 0;
253 	char err[PCAP_ERRBUF_SIZE + 1];
254 
255 	if (pcap_findalldevs(&devs, err) < 0) {
256 		wpa_printf(MSG_DEBUG, "pcap_findalldevs: %s\n", err);
257 		return -1;
258 	}
259 
260 	for (dev = devs; dev && !found; dev = dev->next) {
261 		if (os_strcmp(dev->name, l2->ifname) != 0)
262 			continue;
263 
264 		addr = dev->addresses;
265 		while (addr) {
266 			saddr = (struct sockaddr_in *) addr->addr;
267 			if (saddr && saddr->sin_family == AF_INET) {
268 				os_strlcpy(buf, inet_ntoa(saddr->sin_addr),
269 					   len);
270 				found = 1;
271 				break;
272 			}
273 			addr = addr->next;
274 		}
275 	}
276 
277 	pcap_freealldevs(devs);
278 
279 	return found ? 0 : -1;
280 }
281 
282 
283 void l2_packet_notify_auth_start(struct l2_packet_data *l2)
284 {
285 }
286