libudev/libudev-util-private.c

   1 /*
   2  * libudev - interface to udev device information
   3  *
   4  * Copyright (C) 2003-2009 Kay Sievers <kay.sievers@vrfy.org>
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <stdlib.h>
  13 #include <stdio.h>
  14 #include <stddef.h>
  15 #include <unistd.h>
  16 #include <string.h>
  17 #include <fcntl.h>
  18 #include <errno.h>
  19 #include <ctype.h>
  20 #include <pwd.h>
  21 #include <grp.h>
  22 #include <sys/wait.h>
  23 #include <sys/param.h>
  24
  25 #include "libudev.h"
  26 #include "libudev-private.h"
  27
  28 static int create_path(struct udev *udev, const char *path, bool selinux)
  29 {
  30         char p[UTIL_PATH_SIZE];
  31         char *pos;
  32         struct stat stats;
  33         int err;
  34
  35         util_strscpy(p, sizeof(p), path);
  36         pos = strrchr(p, '/');
  37         if (pos == NULL)
  38                 return 0;
  39         while (pos != p && pos[-1] == '/')
  40                 pos--;
  41         if (pos == p)
  42                 return 0;
  43         pos[0] = '\0';
  44
  45         dbg(udev, "stat '%s'\n", p);
  46         if (stat(p, &stats) == 0) {
  47                 if ((stats.st_mode & S_IFMT) == S_IFDIR)
  48                         return 0;
  49                 else
  50                         return -ENOTDIR;
  51         }
  52
  53         err = util_create_path(udev, p);
  54         if (err != 0)
  55                 return err;
  56
  57         dbg(udev, "mkdir '%s'\n", p);
  58         if (selinux)
  59                 udev_selinux_setfscreatecon(udev, p, S_IFDIR|0755);
  60         err = mkdir(p, 0755);
  61         if (err != 0) {
  62                 err = -errno;
  63                 if (err == -EEXIST && stat(p, &stats) == 0) {
  64                         if ((stats.st_mode & S_IFMT) == S_IFDIR)
  65                                 err = 0;
  66                         else
  67                                 err = -ENOTDIR;
  68                 }
  69         }
  70         if (selinux)
  71                 udev_selinux_resetfscreatecon(udev);
  72         return err;
  73 }
  74
  75 int util_create_path(struct udev *udev, const char *path)
  76 {
  77         return create_path(udev, path, false);
  78 }
  79
  80 int util_create_path_selinux(struct udev *udev, const char *path)
  81 {
  82         return create_path(udev, path, true);
  83 }
  84
  85 int util_delete_path(struct udev *udev, const char *path)
  86 {
  87         char p[UTIL_PATH_SIZE];
  88         char *pos;
  89         int err = 0;
  90
  91         if (path[0] == '/')
  92                 while(path[1] == '/')
  93                         path++;
  94         util_strscpy(p, sizeof(p), path);
  95         pos = strrchr(p, '/');
  96         if (pos == p || pos == NULL)
  97                 return 0;
  98
  99         for (;;) {
 100                 *pos = '\0';
 101                 pos = strrchr(p, '/');
 102
 103                 /* don't remove the last one */
 104                 if ((pos == p) || (pos == NULL))
 105                         break;
 106
 107                 err = rmdir(p);
 108                 if (err < 0) {
 109                         if (errno == ENOENT)
 110                                 err = 0;
 111                         break;
 112                 }
 113         }
 114         return err;
 115 }
 116
 117 /* Reset permissions on the device node, before unlinking it to make sure,
 118  * that permissions of possible hard links will be removed too.
 119  */
 120 int util_unlink_secure(struct udev *udev, const char *filename)
 121 {
 122         int err;
 123
 124         chown(filename, 0, 0);
 125         chmod(filename, 0000);
 126         err = unlink(filename);
 127         if (errno == ENOENT)
 128                 err = 0;
 129         if (err)
 130                 err(udev, "unlink(%s) failed: %m\n", filename);
 131         return err;
 132 }
 133
 134 uid_t util_lookup_user(struct udev *udev, const char *user)
 135 {
 136         char *endptr;
 137         size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
 138         char buf[buflen];
 139         struct passwd pwbuf;
 140         struct passwd *pw;
 141         uid_t uid;
 142
 143         if (strcmp(user, "root") == 0)
 144                 return 0;
 145         uid = strtoul(user, &endptr, 10);
 146         if (endptr[0] == '\0')
 147                 return uid;
 148
 149         errno = getpwnam_r(user, &pwbuf, buf, buflen, &pw);
 150         if (pw != NULL)
 151                 return pw->pw_uid;
 152         if (errno == 0 || errno == ENOENT || errno == ESRCH)
 153                 err(udev, "specified user '%s' unknown\n", user);
 154         else
 155                 err(udev, "error resolving user '%s': %m\n", user);
 156         return 0;
 157 }
 158
 159 gid_t util_lookup_group(struct udev *udev, const char *group)
 160 {
 161         char *endptr;
 162         size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
 163         char *buf;
 164         struct group grbuf;
 165         struct group *gr;
 166         gid_t gid = 0;
 167
 168         if (strcmp(group, "root") == 0)
 169                 return 0;
 170         gid = strtoul(group, &endptr, 10);
 171         if (endptr[0] == '\0')
 172                 return gid;
 173         buf = NULL;
 174         gid = 0;
 175         for (;;) {
 176                 char *newbuf;
 177
 178                 newbuf = realloc(buf, buflen);
 179                 if (!newbuf)
 180                         break;
 181                 buf = newbuf;
 182                 errno = getgrnam_r(group, &grbuf, buf, buflen, &gr);
 183                 if (gr != NULL) {
 184                         gid = gr->gr_gid;
 185                 } else if (errno == ERANGE) {
 186                         buflen *= 2;
 187                         continue;
 188                 } else if (errno == 0 || errno == ENOENT || errno == ESRCH) {
 189                         err(udev, "specified group '%s' unknown\n", group);
 190                 } else {
 191                         err(udev, "error resolving group '%s': %m\n", group);
 192                 }
 193                 break;
 194         }
 195         free(buf);
 196         return gid;
 197 }
 198
 199 /* handle "[<SUBSYSTEM>/<KERNEL>]<attribute>" format */
 200 int util_resolve_subsys_kernel(struct udev *udev, const char *string,
 201                                char *result, size_t maxsize, int read_value)
 202 {
 203         char temp[UTIL_PATH_SIZE];
 204         char *subsys;
 205         char *sysname;
 206         struct udev_device *dev;
 207         char *attr;
 208
 209         if (string[0] != '[')
 210                 return -1;
 211
 212         util_strscpy(temp, sizeof(temp), string);
 213
 214         subsys = &temp[1];
 215
 216         sysname = strchr(subsys, '/');
 217         if (sysname == NULL)
 218                 return -1;
 219         sysname[0] = '\0';
 220         sysname = &sysname[1];
 221
 222         attr = strchr(sysname, ']');
 223         if (attr == NULL)
 224                 return -1;
 225         attr[0] = '\0';
 226         attr = &attr[1];
 227         if (attr[0] == '/')
 228                 attr = &attr[1];
 229         if (attr[0] == '\0')
 230                 attr = NULL;
 231
 232         if (read_value && attr == NULL)
 233                 return -1;
 234
 235         dev = udev_device_new_from_subsystem_sysname(udev, subsys, sysname);
 236         if (dev == NULL)
 237                 return -1;
 238
 239         if (read_value) {
 240                 const char *val;
 241
 242                 val = udev_device_get_sysattr_value(dev, attr);
 243                 if (val != NULL)
 244                         util_strscpy(result, maxsize, val);
 245                 else
 246                         result[0] = '\0';
 247                 info(udev, "value '[%s/%s]%s' is '%s'\n", subsys, sysname, attr, result);
 248         } else {
 249                 size_t l;
 250                 char *s;
 251
 252                 s = result;
 253                 l = util_strpcpyl(&s, maxsize, udev_device_get_syspath(dev), NULL);
 254                 if (attr != NULL)
 255                         util_strpcpyl(&s, l, "/", attr, NULL);
 256                 info(udev, "path '[%s/%s]%s' is '%s'\n", subsys, sysname, attr, result);
 257         }
 258         udev_device_unref(dev);
 259         return 0;
 260 }
 261
 262 int util_run_program(struct udev *udev, const char *command, char **envp,
 263                      char *result, size_t ressize, size_t *reslen,
 264                      const sigset_t *sigmask)
 265 {
 266         int status;
 267         int outpipe[2] = {-1, -1};
 268         int errpipe[2] = {-1, -1};
 269         pid_t pid;
 270         char arg[UTIL_PATH_SIZE];
 271         char program[UTIL_PATH_SIZE];
 272         char *argv[((sizeof(arg) + 1) / 2) + 1];
 273         int devnull;
 274         int i;
 275         int err = 0;
 276
 277         info(udev, "'%s' started\n", command);
 278
 279         /* build argv from command */
 280         util_strscpy(arg, sizeof(arg), command);
 281         i = 0;
 282         if (strchr(arg, ' ') != NULL) {
 283                 char *pos = arg;
 284
 285                 while (pos != NULL && pos[0] != '\0') {
 286                         if (pos[0] == '\'') {
 287                                 /* do not separate quotes */
 288                                 pos++;
 289                                 argv[i] = strsep(&pos, "\'");
 290                                 if (pos != NULL)
 291                                         while (pos[0] == ' ')
 292                                                 pos++;
 293                         } else {
 294                                 argv[i] = strsep(&pos, " ");
 295                                 if (pos != NULL)
 296                                         while (pos[0] == ' ')
 297                                                 pos++;
 298                         }
 299                         dbg(udev, "arg[%i] '%s'\n", i, argv[i]);
 300                         i++;
 301                 }
 302                 argv[i] = NULL;
 303         } else {
 304                 argv[0] = arg;
 305                 argv[1] = NULL;
 306         }
 307
 308         /* prepare pipes from child to parent */
 309         if (result != NULL || udev_get_log_priority(udev) >= LOG_INFO) {
 310                 if (pipe(outpipe) != 0) {
 311                         err(udev, "pipe failed: %m\n");
 312                         return -1;
 313                 }
 314         }
 315         if (udev_get_log_priority(udev) >= LOG_INFO) {
 316                 if (pipe(errpipe) != 0) {
 317                         err(udev, "pipe failed: %m\n");
 318                         return -1;
 319                 }
 320         }
 321
 322         /* allow programs in /lib/udev/ to be called without the path */
 323         if (argv[0][0] != '/') {
 324                 util_strscpyl(program, sizeof(program), LIBEXECDIR "/", argv[0], NULL);
 325                 argv[0] = program;
 326         }
 327
 328         pid = fork();
 329         switch(pid) {
 330         case 0:
 331                 /* child closes parent ends of pipes */
 332                 if (outpipe[READ_END] > 0)
 333                         close(outpipe[READ_END]);
 334                 if (errpipe[READ_END] > 0)
 335                         close(errpipe[READ_END]);
 336
 337                 /* discard child output or connect to pipe */
 338                 devnull = open("/dev/null", O_RDWR);
 339                 if (devnull > 0) {
 340                         dup2(devnull, STDIN_FILENO);
 341                         if (outpipe[WRITE_END] < 0)
 342                                 dup2(devnull, STDOUT_FILENO);
 343                         if (errpipe[WRITE_END] < 0)
 344                                 dup2(devnull, STDERR_FILENO);
 345                         close(devnull);
 346                 } else
 347                         err(udev, "open /dev/null failed: %m\n");
 348                 if (outpipe[WRITE_END] > 0) {
 349                         dup2(outpipe[WRITE_END], STDOUT_FILENO);
 350                         close(outpipe[WRITE_END]);
 351                 }
 352                 if (errpipe[WRITE_END] > 0) {
 353                         dup2(errpipe[WRITE_END], STDERR_FILENO);
 354                         close(errpipe[WRITE_END]);
 355                 }
 356
 357                 if (sigmask)
 358                         sigprocmask(SIG_SETMASK, sigmask, NULL);
 359
 360                 execve(argv[0], argv, envp);
 361                 if (errno == ENOENT || errno == ENOTDIR) {
 362                         /* may be on a filesystem which is not mounted right now */
 363                         info(udev, "program '%s' not found\n", argv[0]);
 364                 } else {
 365                         /* other problems */
 366                         err(udev, "exec of program '%s' failed\n", argv[0]);
 367                 }
 368                 _exit(1);
 369         case -1:
 370                 err(udev, "fork of '%s' failed: %m\n", argv[0]);
 371                 return -1;
 372         default:
 373                 /* read from child if requested */
 374                 if (outpipe[READ_END] > 0 || errpipe[READ_END] > 0) {
 375                         ssize_t count;
 376                         size_t respos = 0;
 377
 378                         /* parent closes child ends of pipes */
 379                         if (outpipe[WRITE_END] > 0)
 380                                 close(outpipe[WRITE_END]);
 381                         if (errpipe[WRITE_END] > 0)
 382                                 close(errpipe[WRITE_END]);
 383
 384                         /* read child output */
 385                         while (outpipe[READ_END] > 0 || errpipe[READ_END] > 0) {
 386                                 int fdcount;
 387                                 fd_set readfds;
 388
 389                                 FD_ZERO(&readfds);
 390                                 if (outpipe[READ_END] > 0)
 391                                         FD_SET(outpipe[READ_END], &readfds);
 392                                 if (errpipe[READ_END] > 0)
 393                                         FD_SET(errpipe[READ_END], &readfds);
 394                                 fdcount = select(MAX(outpipe[READ_END], errpipe[READ_END])+1, &readfds, NULL, NULL, NULL);
 395                                 if (fdcount < 0) {
 396                                         if (errno == EINTR)
 397                                                 continue;
 398                                         err = -1;
 399                                         break;
 400                                 }
 401
 402                                 /* get stdout */
 403                                 if (outpipe[READ_END] > 0 && FD_ISSET(outpipe[READ_END], &readfds)) {
 404                                         char inbuf[1024];
 405                                         char *pos;
 406                                         char *line;
 407
 408                                         count = read(outpipe[READ_END], inbuf, sizeof(inbuf)-1);
 409                                         if (count <= 0) {
 410                                                 close(outpipe[READ_END]);
 411                                                 outpipe[READ_END] = -1;
 412                                                 if (count < 0) {
 413                                                         err(udev, "stdin read failed: %m\n");
 414                                                         err = -1;
 415                                                 }
 416                                                 continue;
 417                                         }
 418                                         inbuf[count] = '\0';
 419
 420                                         /* store result for rule processing */
 421                                         if (result) {
 422                                                 if (respos + count < ressize) {
 423                                                         memcpy(&result[respos], inbuf, count);
 424                                                         respos += count;
 425                                                 } else {
 426                                                         err(udev, "ressize %ld too short\n", (long)ressize);
 427                                                         err = -1;
 428                                                 }
 429                                         }
 430                                         pos = inbuf;
 431                                         while ((line = strsep(&pos, "\n")))
 432                                                 if (pos || line[0] != '\0')
 433                                                         info(udev, "'%s' (stdout) '%s'\n", argv[0], line);
 434                                 }
 435
 436                                 /* get stderr */
 437                                 if (errpipe[READ_END] > 0 && FD_ISSET(errpipe[READ_END], &readfds)) {
 438                                         char errbuf[1024];
 439                                         char *pos;
 440                                         char *line;
 441
 442                                         count = read(errpipe[READ_END], errbuf, sizeof(errbuf)-1);
 443                                         if (count <= 0) {
 444                                                 close(errpipe[READ_END]);
 445                                                 errpipe[READ_END] = -1;
 446                                                 if (count < 0)
 447                                                         err(udev, "stderr read failed: %m\n");
 448                                                 continue;
 449                                         }
 450                                         errbuf[count] = '\0';
 451                                         pos = errbuf;
 452                                         while ((line = strsep(&pos, "\n")))
 453                                                 if (pos || line[0] != '\0')
 454                                                         info(udev, "'%s' (stderr) '%s'\n", argv[0], line);
 455                                 }
 456                         }
 457                         if (outpipe[READ_END] > 0)
 458                                 close(outpipe[READ_END]);
 459                         if (errpipe[READ_END] > 0)
 460                                 close(errpipe[READ_END]);
 461
 462                         /* return the child's stdout string */
 463                         if (result) {
 464                                 result[respos] = '\0';
 465                                 dbg(udev, "result='%s'\n", result);
 466                                 if (reslen)
 467                                         *reslen = respos;
 468                         }
 469                 }
 470                 waitpid(pid, &status, 0);
 471                 if (WIFEXITED(status)) {
 472                         info(udev, "'%s' returned with exitcode %i\n", command, WEXITSTATUS(status));
 473                         if (WEXITSTATUS(status) != 0)
 474                                 err = -1;
 475                 } else {
 476                         err(udev, "'%s' unexpected exit with status 0x%04x\n", command, status);
 477                         err = -1;
 478                 }
 479         }
 480         return err;
 481 }