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 (at) gentoo.org> 5 * Copyright (c) 2001 Johannes Erdfelt <johannes (at) erdfelt.com> 6 * Copyright (c) 2013 Nathan Hjelm <hjelmn (at) 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 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 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 } 149 150 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 } 179 180 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 */ 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 } 263 264 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 } 302 303 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 } 335 336 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
