udev/lib/libudev.c

   1 /*
   2  * libudev - interface to udev device information
   3  *
   4  * Copyright (C) 2008 Kay Sievers <kay.sievers@vrfy.org>
   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 as published by
   8  * the Free Software Foundation, either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include <stdio.h>
  21 #include <stdlib.h>
  22 #include <stddef.h>
  23 #include <stdarg.h>
  24 #include <unistd.h>
  25 #include <errno.h>
  26 #include <string.h>
  27 #include <ctype.h>
  28 #ifdef USE_SELINUX
  29 #include <selinux/selinux.h>
  30 #endif
  31
  32 #include "libudev.h"
  33 #include "libudev-private.h"
  34
  35 struct udev {
  36         int refcount;
  37         void (*log_fn)(struct udev *udev,
  38                        int priority, const char *file, int line, const char *fn,
  39                        const char *format, va_list args);
  40         void *userdata;
  41         char *sys_path;
  42         char *dev_path;
  43         char *rules_path;
  44         int log_priority;
  45 #ifdef USE_SELINUX
  46         int selinux_initialized;
  47         int selinux_enabled;
  48         security_context_t selinux_prev_scontext;
  49 #endif
  50         int run;
  51 };
  52
  53 void udev_log(struct udev *udev,
  54               int priority, const char *file, int line, const char *fn,
  55               const char *format, ...)
  56 {
  57         va_list args;
  58
  59         if (priority > udev->log_priority)
  60                 return;
  61
  62         va_start(args, format);
  63         udev->log_fn(udev, priority, file, line, fn, format, args);
  64         va_end(args);
  65 }
  66
  67 static void log_stderr(struct udev *udev,
  68                        int priority, const char *file, int line, const char *fn,
  69                        const char *format, va_list args)
  70 {
  71         fprintf(stderr, "libudev: %s: ", fn);
  72         vfprintf(stderr, format, args);
  73 }
  74
  75 static void selinux_init(struct udev *udev)
  76 {
  77 #ifdef USE_SELINUX
  78         /*
  79          * record the present security context, for file-creation
  80          * restoration creation purposes.
  81          */
  82         udev->selinux_enabled = (is_selinux_enabled() > 0);
  83         info(udev, "selinux=%i\n", udev->selinux_enabled);
  84         if (udev->selinux_enabled) {
  85                 matchpathcon_init_prefix(NULL, udev_get_dev_path(udev));
  86                 if (getfscreatecon(&udev->selinux_prev_scontext) < 0) {
  87                         err(udev, "getfscreatecon failed\n");
  88                         udev->selinux_prev_scontext = NULL;
  89                 }
  90         }
  91         udev->selinux_initialized = 1;
  92 #endif
  93 }
  94
  95 void *udev_get_userdata(struct udev *udev)
  96 {
  97         if (udev == NULL)
  98                 return NULL;
  99         return udev->userdata;
 100 }
 101
 102 void udev_set_userdata(struct udev *udev, void *userdata)
 103 {
 104         if (udev == NULL)
 105                 return;
 106         udev->userdata = userdata;
 107 }
 108
 109 static void selinux_exit(struct udev *udev)
 110 {
 111 #ifdef USE_SELINUX
 112         if (!udev->selinux_initialized)
 113                 return;
 114         if (udev->selinux_enabled) {
 115                 freecon(udev->selinux_prev_scontext);
 116                 udev->selinux_prev_scontext = NULL;
 117         }
 118 #endif
 119 }
 120
 121 void udev_selinux_lsetfilecon(struct udev *udev, const char *file, unsigned int mode)
 122 {
 123 #ifdef USE_SELINUX
 124         if (!udev->selinux_initialized)
 125                 selinux_init(udev);
 126         if (udev->selinux_enabled) {
 127                 security_context_t scontext = NULL;
 128
 129                 if (matchpathcon(file, mode, &scontext) < 0) {
 130                         err(udev, "matchpathcon(%s) failed\n", file);
 131                         return;
 132                 }
 133                 if (lsetfilecon(file, scontext) < 0)
 134                         err(udev, "setfilecon %s failed: %s\n", file, strerror(errno));
 135                 freecon(scontext);
 136         }
 137 #endif
 138 }
 139
 140 void udev_selinux_setfscreatecon(struct udev *udev, const char *file, unsigned int mode)
 141 {
 142 #ifdef USE_SELINUX
 143         if (!udev->selinux_initialized)
 144                 selinux_init(udev);
 145         if (udev->selinux_enabled) {
 146                 security_context_t scontext = NULL;
 147
 148                 if (matchpathcon(file, mode, &scontext) < 0) {
 149                         err(udev, "matchpathcon(%s) failed\n", file);
 150                         return;
 151                 }
 152                 if (setfscreatecon(scontext) < 0)
 153                         err(udev, "setfscreatecon %s failed: %s\n", file, strerror(errno));
 154                 freecon(scontext);
 155         }
 156 #endif
 157 }
 158
 159 void udev_selinux_resetfscreatecon(struct udev *udev)
 160 {
 161 #ifdef USE_SELINUX
 162         if (!udev->selinux_initialized)
 163                 selinux_init(udev);
 164         if (udev->selinux_enabled) {
 165                 if (setfscreatecon(udev->selinux_prev_scontext) < 0)
 166                         err(udev, "setfscreatecon failed: %s\n", strerror(errno));
 167         }
 168 #endif
 169 }
 170
 171 /**
 172  * udev_new:
 173  *
 174  * Create udev library context.
 175  *
 176  * The initial refcount is 1, and needs to be decremented to
 177  * release the ressources of the udev library context.
 178  *
 179  * Returns: a new udev library context
 180  **/
 181 struct udev *udev_new(void)
 182 {
 183         struct udev *udev;
 184         const char *env;
 185         char *config_file;
 186         FILE *f;
 187
 188         udev = malloc(sizeof(struct udev));
 189         if (udev == NULL)
 190                 return NULL;
 191         memset(udev, 0x00, (sizeof(struct udev)));
 192         udev->refcount = 1;
 193         udev->log_fn = log_stderr;
 194         udev->log_priority = LOG_ERR;
 195         udev->run = 1;
 196         udev->dev_path = strdup(UDEV_PREFIX "/dev");
 197         udev->sys_path = strdup("/sys");
 198         config_file = strdup(SYSCONFDIR "/udev/udev.conf");
 199         if (udev->dev_path == NULL ||
 200             udev->sys_path == NULL ||
 201             config_file == NULL)
 202                 goto err;
 203
 204         /* settings by environment and config file */
 205         env = getenv("SYSFS_PATH");
 206         if (env != NULL) {
 207                 free(udev->sys_path);
 208                 udev->sys_path = strdup(env);
 209                 util_remove_trailing_chars(udev->sys_path, '/');
 210         }
 211
 212         env = getenv("UDEV_RUN");
 213         if (env != NULL && strcmp(env, "0") == 0)
 214                 udev->run = 0;
 215
 216         env = getenv("UDEV_CONFIG_FILE");
 217         if (env != NULL) {
 218                 free(config_file);
 219                 config_file = strdup(env);
 220                 util_remove_trailing_chars(config_file, '/');
 221         }
 222         if (config_file == NULL)
 223                 goto err;
 224         f = fopen(config_file, "r");
 225         if (f != NULL) {
 226                 char line[UTIL_LINE_SIZE];
 227                 int line_nr = 0;
 228
 229                 while (fgets(line, sizeof(line), f)) {
 230                         size_t len;
 231                         char *key;
 232                         char *val;
 233
 234                         line_nr++;
 235
 236                         /* find key */
 237                         key = line;
 238                         while (isspace(key[0]))
 239                                 key++;
 240
 241                         /* comment or empty line */
 242                         if (key[0] == '#' || key[0] == '\0')
 243                                 continue;
 244
 245                         /* split key/value */
 246                         val = strchr(key, '=');
 247                         if (val == NULL) {
 248                                 err(udev, "missing <key>=<value> in '%s'[%i], skip line\n", config_file, line_nr);
 249                                 continue;
 250                         }
 251                         val[0] = '\0';
 252                         val++;
 253
 254                         /* find value */
 255                         while (isspace(val[0]))
 256                                 val++;
 257
 258                         /* terminate key */
 259                         len = strlen(key);
 260                         if (len == 0)
 261                                 continue;
 262                         while (isspace(key[len-1]))
 263                                 len--;
 264                         key[len] = '\0';
 265
 266                         /* terminate value */
 267                         len = strlen(val);
 268                         if (len == 0)
 269                                 continue;
 270                         while (isspace(val[len-1]))
 271                                 len--;
 272                         val[len] = '\0';
 273
 274                         if (len == 0)
 275                                 continue;
 276
 277                         /* unquote */
 278                         if (val[0] == '"' || val[0] == '\'') {
 279                                 if (val[len-1] != val[0]) {
 280                                         err(udev, "inconsistent quoting in '%s'[%i], skip line\n", config_file, line_nr);
 281                                         continue;
 282                                 }
 283                                 val[len-1] = '\0';
 284                                 val++;
 285                         }
 286
 287                         if (strcasecmp(key, "udev_log") == 0) {
 288                                 udev->log_priority = util_log_priority(val);
 289                                 continue;
 290                         }
 291                         if (strcasecmp(key, "udev_root") == 0) {
 292                                 free(udev->dev_path);
 293                                 udev->dev_path = strdup(val);
 294                                 util_remove_trailing_chars(udev->dev_path, '/');
 295                                 continue;
 296                         }
 297                         if (strcasecmp(key, "udev_rules") == 0) {
 298                                 free(udev->rules_path);
 299                                 udev->rules_path = strdup(val);
 300                                 util_remove_trailing_chars(udev->rules_path, '/');
 301                                 continue;
 302                         }
 303                 }
 304                 fclose(f);
 305         }
 306
 307         env = getenv("UDEV_ROOT");
 308         if (env != NULL) {
 309                 free(udev->dev_path);
 310                 udev->dev_path = strdup(env);
 311                 util_remove_trailing_chars(udev->dev_path, '/');
 312         }
 313
 314         env = getenv("UDEV_LOG");
 315         if (env != NULL)
 316                 udev->log_priority = util_log_priority(env);
 317
 318         if (udev->dev_path == NULL || udev->sys_path == NULL)
 319                 goto err;
 320         info(udev, "context %p created\n", udev);
 321         info(udev, "log_priority=%d\n", udev->log_priority);
 322         info(udev, "config_file='%s'\n", config_file);
 323         info(udev, "dev_path='%s'\n", udev->dev_path);
 324         info(udev, "sys_path='%s'\n", udev->sys_path);
 325         if (udev->rules_path != NULL)
 326                 info(udev, "rules_path='%s'\n", udev->rules_path);
 327         free(config_file);
 328         return udev;
 329 err:
 330         free(config_file);
 331         err(udev, "context creation failed\n");
 332         udev_unref(udev);
 333         return NULL;
 334 }
 335
 336 /**
 337  * udev_ref:
 338  * @udev: udev library context
 339  *
 340  * Take a reference of the udev library context.
 341  *
 342  * Returns: the passed udev library context
 343  **/
 344 struct udev *udev_ref(struct udev *udev)
 345 {
 346         if (udev == NULL)
 347                 return NULL;
 348         udev->refcount++;
 349         return udev;
 350 }
 351
 352 /**
 353  * udev_unref:
 354  * @udev: udev library context
 355  *
 356  * Drop a reference of the udev library context. If the refcount
 357  * reaches zero, the ressources of the context will be released.
 358  *
 359  **/
 360 void udev_unref(struct udev *udev)
 361 {
 362         if (udev == NULL)
 363                 return;
 364         udev->refcount--;
 365         if (udev->refcount > 0)
 366                 return;
 367         selinux_exit(udev);
 368         free(udev->dev_path);
 369         free(udev->sys_path);
 370         free(udev->rules_path);
 371         info(udev, "context %p released\n", udev);
 372         free(udev);
 373 }
 374
 375 /**
 376  * udev_set_log_fn:
 377  * @udev: udev library context
 378  * @log_fn: function to be called for logging messages
 379  *
 380  * The built-in logging, which writes to stderr if the
 381  * LIBUDEV_DEBUG environment variable is set, can be
 382  * overridden by a custom function, to plug log messages
 383  * into the users logging functionality.
 384  *
 385  **/
 386 void udev_set_log_fn(struct udev *udev,
 387                      void (*log_fn)(struct udev *udev,
 388                                     int priority, const char *file, int line, const char *fn,
 389                                     const char *format, va_list args))
 390 {
 391         udev->log_fn = log_fn;
 392         info(udev, "custom logging function %p registered\n", udev);
 393 }
 394
 395 int udev_get_log_priority(struct udev *udev)
 396 {
 397         return udev->log_priority;
 398 }
 399
 400 void udev_set_log_priority(struct udev *udev, int priority)
 401 {
 402         udev->log_priority = priority;
 403 }
 404
 405 const char *udev_get_rules_path(struct udev *udev)
 406 {
 407         return udev->rules_path;
 408 }
 409
 410 int udev_get_run(struct udev *udev)
 411 {
 412         return udev->run;
 413 }
 414
 415 /**
 416  * udev_get_sys_path:
 417  * @udev: udev library context
 418  *
 419  * Retrieve the sysfs mount point. The default is "/sys". For
 420  * testing purposes, it can be overridden with the environment
 421  * variable SYSFS_PATH.
 422  *
 423  * Returns: the sys mount point
 424  **/
 425 const char *udev_get_sys_path(struct udev *udev)
 426 {
 427         if (udev == NULL)
 428                 return NULL;
 429         return udev->sys_path;
 430 }
 431
 432 /**
 433  * udev_get_dev_path:
 434  * @udev: udev library context
 435  *
 436  * Retrieve the device directory path. The default value is "/dev",
 437  * the actual value may be overridden in the udev configuration
 438  * file.
 439  *
 440  * Returns: the device directory path
 441  **/
 442 const char *udev_get_dev_path(struct udev *udev)
 443 {
 444         if (udev == NULL)
 445                 return NULL;
 446         return udev->dev_path;
 447 }