1 /* -*- Mode: C; c-basic-offset:8 ; indent-tabs-mode:t -*- */
2 /*
3 * Linux usbfs backend for libusb
4 * Copyright (C) 2007-2009 Daniel Drake <dsd@gentoo.org>
5 * Copyright (c) 2001 Johannes Erdfelt <johannes@erdfelt.com>
6 * Copyright (c) 2013 Nathan Hjelm <hjelmn@mac.com>
7 *
8 * This library is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
12 *
13 * This library is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
17 *
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with this library; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 */
22
23 #include "config.h"
24 #include "libusb.h"
25 #include "libusbi.h"
26 #include "linux_usbfs.h"
27
28 #include <ctype.h>
29 #include <dirent.h>
30 #include <errno.h>
31 #include <fcntl.h>
32 #include <poll.h>
33 #include <stdio.h>
34 #include <stdlib.h>
35 #include <string.h>
36 #include <sys/types.h>
37
38 #ifdef HAVE_ASM_TYPES_H
39 #include <asm/types.h>
40 #endif
41
42 #ifdef HAVE_SYS_SOCKET_H
43 #include <sys/socket.h>
44 #endif
45
46 #include <arpa/inet.h>
47
48 #ifdef HAVE_LINUX_NETLINK_H
49 #include <linux/netlink.h>
50 #endif
51
52 #ifdef HAVE_LINUX_FILTER_H
53 #include <linux/filter.h>
54 #endif
55
56 #define KERNEL 1
57
58 static int linux_netlink_socket = -1;
59 static int netlink_control_pipe[2] = { -1, -1 };
60 static pthread_t libusb_linux_event_thread;
61
62 static void *linux_netlink_event_thread_main(void *arg);
63
64 struct sockaddr_nl snl = { .nl_family=AF_NETLINK, .nl_groups=KERNEL };
65
set_fd_cloexec_nb(int fd)66 static int set_fd_cloexec_nb (int fd)
67 {
68 int flags;
69
70 #if defined(FD_CLOEXEC)
71 flags = fcntl (linux_netlink_socket, F_GETFD);
72 if (0 > flags) {
73 return -1;
74 }
75
76 if (!(flags & FD_CLOEXEC)) {
77 fcntl (linux_netlink_socket, F_SETFD, flags | FD_CLOEXEC);
78 }
79 #endif
80
81 flags = fcntl (linux_netlink_socket, F_GETFL);
82 if (0 > flags) {
83 return -1;
84 }
85
86 if (!(flags & O_NONBLOCK)) {
87 fcntl (linux_netlink_socket, F_SETFL, flags | O_NONBLOCK);
88 }
89
90 return 0;
91 }
92
linux_netlink_start_event_monitor(void)93 int linux_netlink_start_event_monitor(void)
94 {
95 int socktype = SOCK_RAW;
96 int ret;
97
98 snl.nl_groups = KERNEL;
99
100 #if defined(SOCK_CLOEXEC)
101 socktype |= SOCK_CLOEXEC;
102 #endif
103 #if defined(SOCK_NONBLOCK)
104 socktype |= SOCK_NONBLOCK;
105 #endif
106
107 linux_netlink_socket = socket(PF_NETLINK, socktype, NETLINK_KOBJECT_UEVENT);
108 if (-1 == linux_netlink_socket && EINVAL == errno) {
109 linux_netlink_socket = socket(PF_NETLINK, SOCK_RAW, NETLINK_KOBJECT_UEVENT);
110 }
111
112 if (-1 == linux_netlink_socket) {
113 return LIBUSB_ERROR_OTHER;
114 }
115
116 ret = set_fd_cloexec_nb (linux_netlink_socket);
117 if (0 != ret) {
118 close (linux_netlink_socket);
119 linux_netlink_socket = -1;
120 return LIBUSB_ERROR_OTHER;
121 }
122
123 ret = bind(linux_netlink_socket, (struct sockaddr *) &snl, sizeof(snl));
124 if (0 != ret) {
125 close(linux_netlink_socket);
126 return LIBUSB_ERROR_OTHER;
127 }
128
129 /* TODO -- add authentication */
130 /* setsockopt(linux_netlink_socket, SOL_SOCKET, SO_PASSCRED, &one, sizeof(one)); */
131
132 ret = usbi_pipe(netlink_control_pipe);
133 if (ret) {
134 usbi_err(NULL, "could not create netlink control pipe");
135 close(linux_netlink_socket);
136 return LIBUSB_ERROR_OTHER;
137 }
138
139 ret = pthread_create(&libusb_linux_event_thread, NULL, linux_netlink_event_thread_main, NULL);
140 if (0 != ret) {
141 close(netlink_control_pipe[0]);
142 close(netlink_control_pipe[1]);
143 close(linux_netlink_socket);
144 return LIBUSB_ERROR_OTHER;
145 }
146
147 return LIBUSB_SUCCESS;
148 }
149
linux_netlink_stop_event_monitor(void)150 int linux_netlink_stop_event_monitor(void)
151 {
152 int r;
153 char dummy = 1;
154
155 if (-1 == linux_netlink_socket) {
156 /* already closed. nothing to do */
157 return LIBUSB_SUCCESS;
158 }
159
160 /* Write some dummy data to the control pipe and
161 * wait for the thread to exit */
162 r = usbi_write(netlink_control_pipe[1], &dummy, sizeof(dummy));
163 if (r <= 0) {
164 usbi_warn(NULL, "netlink control pipe signal failed");
165 }
166 pthread_join(libusb_linux_event_thread, NULL);
167
168 close(linux_netlink_socket);
169 linux_netlink_socket = -1;
170
171 /* close and reset control pipe */
172 close(netlink_control_pipe[0]);
173 close(netlink_control_pipe[1]);
174 netlink_control_pipe[0] = -1;
175 netlink_control_pipe[1] = -1;
176
177 return LIBUSB_SUCCESS;
178 }
179
netlink_message_parse(const char * buffer,size_t len,const char * key)180 static const char *netlink_message_parse (const char *buffer, size_t len, const char *key)
181 {
182 size_t keylen = strlen(key);
183 size_t offset;
184
185 for (offset = 0 ; offset < len && '\0' != buffer[offset] ; offset += strlen(buffer + offset) + 1) {
186 if (0 == strncmp(buffer + offset, key, keylen) &&
187 '=' == buffer[offset + keylen]) {
188 return buffer + offset + keylen + 1;
189 }
190 }
191
192 return NULL;
193 }
194
195 /* parse parts of netlink message common to both libudev and the kernel */
linux_netlink_parse(char * buffer,size_t len,int * detached,const char ** sys_name,uint8_t * busnum,uint8_t * devaddr)196 static int linux_netlink_parse(char *buffer, size_t len, int *detached, const char **sys_name,
197 uint8_t *busnum, uint8_t *devaddr) {
198 const char *tmp;
199 int i;
200
201 errno = 0;
202
203 *sys_name = NULL;
204 *detached = 0;
205 *busnum = 0;
206 *devaddr = 0;
207
208 tmp = netlink_message_parse((const char *) buffer, len, "ACTION");
209 if (tmp == NULL)
210 return -1;
211 if (0 == strcmp(tmp, "remove")) {
212 *detached = 1;
213 } else if (0 != strcmp(tmp, "add")) {
214 usbi_dbg("unknown device action %s", tmp);
215 return -1;
216 }
217
218 /* check that this is a usb message */
219 tmp = netlink_message_parse(buffer, len, "SUBSYSTEM");
220 if (NULL == tmp || 0 != strcmp(tmp, "usb")) {
221 /* not usb. ignore */
222 return -1;
223 }
224
225 tmp = netlink_message_parse(buffer, len, "BUSNUM");
226 if (NULL == tmp) {
227 /* no bus number (likely a usb interface). ignore*/
228 return -1;
229 }
230
231 *busnum = (uint8_t)(strtoul(tmp, NULL, 10) & 0xff);
232 if (errno) {
233 errno = 0;
234 return -1;
235 }
236
237 tmp = netlink_message_parse(buffer, len, "DEVNUM");
238 if (NULL == tmp) {
239 return -1;
240 }
241
242 *devaddr = (uint8_t)(strtoul(tmp, NULL, 10) & 0xff);
243 if (errno) {
244 errno = 0;
245 return -1;
246 }
247
248 tmp = netlink_message_parse(buffer, len, "DEVPATH");
249 if (NULL == tmp) {
250 return -1;
251 }
252
253 for (i = strlen(tmp) - 1 ; i ; --i) {
254 if ('/' ==tmp[i]) {
255 *sys_name = tmp + i + 1;
256 break;
257 }
258 }
259
260 /* found a usb device */
261 return 0;
262 }
263
linux_netlink_read_message(void)264 static int linux_netlink_read_message(void)
265 {
266 unsigned char buffer[1024];
267 struct iovec iov = {.iov_base = buffer, .iov_len = sizeof(buffer)};
268 struct msghdr meh = { .msg_iov=&iov, .msg_iovlen=1,
269 .msg_name=&snl, .msg_namelen=sizeof(snl) };
270 const char *sys_name = NULL;
271 uint8_t busnum, devaddr;
272 int detached, r;
273 size_t len;
274
275 /* read netlink message */
276 memset(buffer, 0, sizeof(buffer));
277 len = recvmsg(linux_netlink_socket, &meh, 0);
278 if (len < 32) {
279 if (errno != EAGAIN)
280 usbi_dbg("error recieving message from netlink");
281 return -1;
282 }
283
284 /* TODO -- authenticate this message is from the kernel or udevd */
285
286 r = linux_netlink_parse(buffer, len, &detached, &sys_name,
287 &busnum, &devaddr);
288 if (r)
289 return r;
290
291 usbi_dbg("netlink hotplug found device busnum: %hhu, devaddr: %hhu, sys_name: %s, removed: %s",
292 busnum, devaddr, sys_name, detached ? "yes" : "no");
293
294 /* signal device is available (or not) to all contexts */
295 if (detached)
296 linux_device_disconnected(busnum, devaddr, sys_name);
297 else
298 linux_hotplug_enumerate(busnum, devaddr, sys_name);
299
300 return 0;
301 }
302
linux_netlink_event_thread_main(void * arg)303 static void *linux_netlink_event_thread_main(void *arg)
304 {
305 char dummy;
306 int r;
307 struct pollfd fds[] = {
308 { .fd = netlink_control_pipe[0],
309 .events = POLLIN },
310 { .fd = linux_netlink_socket,
311 .events = POLLIN },
312 };
313
314 /* silence compiler warning */
315 (void) arg;
316
317 while (poll(fds, 2, -1) >= 0) {
318 if (fds[0].revents & POLLIN) {
319 /* activity on control pipe, read the byte and exit */
320 r = usbi_read(netlink_control_pipe[0], &dummy, sizeof(dummy));
321 if (r <= 0) {
322 usbi_warn(NULL, "netlink control pipe read failed");
323 }
324 break;
325 }
326 if (fds[1].revents & POLLIN) {
327 usbi_mutex_static_lock(&linux_hotplug_lock);
328 linux_netlink_read_message();
329 usbi_mutex_static_unlock(&linux_hotplug_lock);
330 }
331 }
332
333 return NULL;
334 }
335
linux_netlink_hotplug_poll(void)336 void linux_netlink_hotplug_poll(void)
337 {
338 int r;
339
340 usbi_mutex_static_lock(&linux_hotplug_lock);
341 do {
342 r = linux_netlink_read_message();
343 } while (r == 0);
344 usbi_mutex_static_unlock(&linux_hotplug_lock);
345 }
346