xref: /freebsd/contrib/wpa/src/l2_packet/l2_packet_privsep.c (revision d1d015864103b253b3fcb2f72a0da5b0cfeb31b6)
1 /*
2  * WPA Supplicant - Layer2 packet handling with privilege separation
3  * Copyright (c) 2007, Jouni Malinen <j@w1.fi>
4  *
5  * This software may be distributed under the terms of the BSD license.
6  * See README for more details.
7  */
8 
9 #include "includes.h"
10 #include <sys/un.h>
11 
12 #include "common.h"
13 #include "eloop.h"
14 #include "l2_packet.h"
15 #include "common/privsep_commands.h"
16 
17 
18 struct l2_packet_data {
19 	int fd; /* UNIX domain socket for privsep access */
20 	void (*rx_callback)(void *ctx, const u8 *src_addr,
21 			    const u8 *buf, size_t len);
22 	void *rx_callback_ctx;
23 	u8 own_addr[ETH_ALEN];
24 	char *own_socket_path;
25 	struct sockaddr_un priv_addr;
26 };
27 
28 
29 static int wpa_priv_cmd(struct l2_packet_data *l2, int cmd,
30 			const void *data, size_t data_len)
31 {
32 	struct msghdr msg;
33 	struct iovec io[2];
34 
35 	io[0].iov_base = &cmd;
36 	io[0].iov_len = sizeof(cmd);
37 	io[1].iov_base = (u8 *) data;
38 	io[1].iov_len = data_len;
39 
40 	os_memset(&msg, 0, sizeof(msg));
41 	msg.msg_iov = io;
42 	msg.msg_iovlen = data ? 2 : 1;
43 	msg.msg_name = &l2->priv_addr;
44 	msg.msg_namelen = sizeof(l2->priv_addr);
45 
46 	if (sendmsg(l2->fd, &msg, 0) < 0) {
47 		perror("L2: sendmsg(cmd)");
48 		return -1;
49 	}
50 
51 	return 0;
52 }
53 
54 
55 int l2_packet_get_own_addr(struct l2_packet_data *l2, u8 *addr)
56 {
57 	os_memcpy(addr, l2->own_addr, ETH_ALEN);
58 	return 0;
59 }
60 
61 
62 int l2_packet_send(struct l2_packet_data *l2, const u8 *dst_addr, u16 proto,
63 		   const u8 *buf, size_t len)
64 {
65 	struct msghdr msg;
66 	struct iovec io[4];
67 	int cmd = PRIVSEP_CMD_L2_SEND;
68 
69 	io[0].iov_base = &cmd;
70 	io[0].iov_len = sizeof(cmd);
71 	io[1].iov_base = &dst_addr;
72 	io[1].iov_len = ETH_ALEN;
73 	io[2].iov_base = &proto;
74 	io[2].iov_len = 2;
75 	io[3].iov_base = (u8 *) buf;
76 	io[3].iov_len = len;
77 
78 	os_memset(&msg, 0, sizeof(msg));
79 	msg.msg_iov = io;
80 	msg.msg_iovlen = 4;
81 	msg.msg_name = &l2->priv_addr;
82 	msg.msg_namelen = sizeof(l2->priv_addr);
83 
84 	if (sendmsg(l2->fd, &msg, 0) < 0) {
85 		perror("L2: sendmsg(packet_send)");
86 		return -1;
87 	}
88 
89 	return 0;
90 }
91 
92 
93 static void l2_packet_receive(int sock, void *eloop_ctx, void *sock_ctx)
94 {
95 	struct l2_packet_data *l2 = eloop_ctx;
96 	u8 buf[2300];
97 	int res;
98 	struct sockaddr_un from;
99 	socklen_t fromlen = sizeof(from);
100 
101 	os_memset(&from, 0, sizeof(from));
102 	res = recvfrom(sock, buf, sizeof(buf), 0, (struct sockaddr *) &from,
103 		       &fromlen);
104 	if (res < 0) {
105 		perror("l2_packet_receive - recvfrom");
106 		return;
107 	}
108 	if (res < ETH_ALEN) {
109 		wpa_printf(MSG_DEBUG, "L2: Too show packet received");
110 		return;
111 	}
112 
113 	if (from.sun_family != AF_UNIX ||
114 	    os_strncmp(from.sun_path, l2->priv_addr.sun_path,
115 		       sizeof(from.sun_path)) != 0) {
116 		wpa_printf(MSG_DEBUG, "L2: Received message from unexpected "
117 			   "source");
118 		return;
119 	}
120 
121 	l2->rx_callback(l2->rx_callback_ctx, buf, buf + ETH_ALEN,
122 			res - ETH_ALEN);
123 }
124 
125 
126 struct l2_packet_data * l2_packet_init(
127 	const char *ifname, const u8 *own_addr, unsigned short protocol,
128 	void (*rx_callback)(void *ctx, const u8 *src_addr,
129 			    const u8 *buf, size_t len),
130 	void *rx_callback_ctx, int l2_hdr)
131 {
132 	struct l2_packet_data *l2;
133 	char *own_dir = "/tmp";
134 	char *priv_dir = "/var/run/wpa_priv";
135 	size_t len;
136 	static unsigned int counter = 0;
137 	struct sockaddr_un addr;
138 	fd_set rfds;
139 	struct timeval tv;
140 	int res;
141 	u8 reply[ETH_ALEN + 1];
142 	int reg_cmd[2];
143 
144 	l2 = os_zalloc(sizeof(struct l2_packet_data));
145 	if (l2 == NULL)
146 		return NULL;
147 	l2->rx_callback = rx_callback;
148 	l2->rx_callback_ctx = rx_callback_ctx;
149 
150 	len = os_strlen(own_dir) + 50;
151 	l2->own_socket_path = os_malloc(len);
152 	if (l2->own_socket_path == NULL) {
153 		os_free(l2);
154 		return NULL;
155 	}
156 	os_snprintf(l2->own_socket_path, len, "%s/wpa_privsep-l2-%d-%d",
157 		    own_dir, getpid(), counter++);
158 
159 	l2->priv_addr.sun_family = AF_UNIX;
160 	os_snprintf(l2->priv_addr.sun_path, sizeof(l2->priv_addr.sun_path),
161 		    "%s/%s", priv_dir, ifname);
162 
163 	l2->fd = socket(PF_UNIX, SOCK_DGRAM, 0);
164 	if (l2->fd < 0) {
165 		perror("socket(PF_UNIX)");
166 		os_free(l2->own_socket_path);
167 		l2->own_socket_path = NULL;
168 		os_free(l2);
169 		return NULL;
170 	}
171 
172 	os_memset(&addr, 0, sizeof(addr));
173 	addr.sun_family = AF_UNIX;
174 	os_strlcpy(addr.sun_path, l2->own_socket_path, sizeof(addr.sun_path));
175 	if (bind(l2->fd, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
176 		perror("l2-pkt-privsep: bind(PF_UNIX)");
177 		goto fail;
178 	}
179 
180 	reg_cmd[0] = protocol;
181 	reg_cmd[1] = l2_hdr;
182 	if (wpa_priv_cmd(l2, PRIVSEP_CMD_L2_REGISTER, reg_cmd, sizeof(reg_cmd))
183 	    < 0) {
184 		wpa_printf(MSG_ERROR, "L2: Failed to register with wpa_priv");
185 		goto fail;
186 	}
187 
188 	FD_ZERO(&rfds);
189 	FD_SET(l2->fd, &rfds);
190 	tv.tv_sec = 5;
191 	tv.tv_usec = 0;
192 	res = select(l2->fd + 1, &rfds, NULL, NULL, &tv);
193 	if (res < 0 && errno != EINTR) {
194 		perror("select");
195 		goto fail;
196 	}
197 
198 	if (FD_ISSET(l2->fd, &rfds)) {
199 		res = recv(l2->fd, reply, sizeof(reply), 0);
200 		if (res < 0) {
201 			perror("recv");
202 			goto fail;
203 		}
204 	} else {
205 		wpa_printf(MSG_DEBUG, "L2: Timeout while waiting for "
206 			   "registration reply");
207 		goto fail;
208 	}
209 
210 	if (res != ETH_ALEN) {
211 		wpa_printf(MSG_DEBUG, "L2: Unexpected registration reply "
212 			   "(len=%d)", res);
213 	}
214 	os_memcpy(l2->own_addr, reply, ETH_ALEN);
215 
216 	eloop_register_read_sock(l2->fd, l2_packet_receive, l2, NULL);
217 
218 	return l2;
219 
220 fail:
221 	close(l2->fd);
222 	l2->fd = -1;
223 	unlink(l2->own_socket_path);
224 	os_free(l2->own_socket_path);
225 	l2->own_socket_path = NULL;
226 	os_free(l2);
227 	return NULL;
228 }
229 
230 
231 void l2_packet_deinit(struct l2_packet_data *l2)
232 {
233 	if (l2 == NULL)
234 		return;
235 
236 	if (l2->fd >= 0) {
237 		wpa_priv_cmd(l2, PRIVSEP_CMD_L2_UNREGISTER, NULL, 0);
238 		eloop_unregister_read_sock(l2->fd);
239 		close(l2->fd);
240 	}
241 
242 	if (l2->own_socket_path) {
243 		unlink(l2->own_socket_path);
244 		os_free(l2->own_socket_path);
245 	}
246 
247 	os_free(l2);
248 }
249 
250 
251 int l2_packet_get_ip_addr(struct l2_packet_data *l2, char *buf, size_t len)
252 {
253 	/* TODO */
254 	return -1;
255 }
256 
257 
258 void l2_packet_notify_auth_start(struct l2_packet_data *l2)
259 {
260 	wpa_priv_cmd(l2, PRIVSEP_CMD_L2_NOTIFY_AUTH_START, NULL, 0);
261 }
262