lxcfs.c

   1 /* lxcfs
   2  *
   3  * Copyright © 2014 Canonical, Inc
   4  * Author: Serge Hallyn <serge.hallyn@ubuntu.com>
   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 version 2, as
   8  * published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18  */
  19
  20 /*
  21  * NOTES - make sure to run this as -s to avoid threading.
  22  * TODO - can we enforce that here from the code?
  23  */
  24 #define FUSE_USE_VERSION 26
  25
  26 #include <stdio.h>
  27 #include <dirent.h>
  28 #include <fcntl.h>
  29 #include <fuse.h>
  30 #include <unistd.h>
  31 #include <errno.h>
  32 #include <stdbool.h>
  33 #include <time.h>
  34 #include <string.h>
  35 #include <stdlib.h>
  36 #include <libgen.h>
  37
  38 #include <nih/alloc.h>
  39 #include <nih/string.h>
  40
  41 #include "cgmanager.h"
  42
  43 struct lxcfs_state {
  44         /*
  45          * a null-terminated, nih-allocated list of the mounted subsystems.  We
  46          * detect this at startup.
  47          */
  48         char **subsystems;
  49 };
  50 #define LXCFS_DATA ((struct lxcfs_state *) fuse_get_context()->private_data)
  51
  52 /*
  53  * Given a open file * to /proc/pid/{u,g}id_map, and an id
  54  * valid in the caller's namespace, return the id mapped into
  55  * pid's namespace.
  56  * Returns the mapped id, or -1 on error.
  57  */
  58 unsigned int
  59 convert_id_to_ns(FILE *idfile, unsigned int in_id)
  60 {
  61         unsigned int nsuid,   // base id for a range in the idfile's namespace
  62                      hostuid, // base id for a range in the caller's namespace
  63                      count;   // number of ids in this range
  64         char line[400];
  65         int ret;
  66
  67         fseek(idfile, 0L, SEEK_SET);
  68         while (fgets(line, 400, idfile)) {
  69                 ret = sscanf(line, "%u %u %u\n", &nsuid, &hostuid, &count);
  70                 if (ret != 3)
  71                         continue;
  72                 if (hostuid + count < hostuid || nsuid + count < nsuid) {
  73                         /*
  74                          * uids wrapped around - unexpected as this is a procfile,
  75                          * so just bail.
  76                          */
  77                         fprintf(stderr, "pid wrapparound at entry %u %u %u in %s",
  78                                 nsuid, hostuid, count, line);
  79                         return -1;
  80                 }
  81                 if (hostuid <= in_id && hostuid+count > in_id) {
  82                         /*
  83                          * now since hostuid <= in_id < hostuid+count, and
  84                          * hostuid+count and nsuid+count do not wrap around,
  85                          * we know that nsuid+(in_id-hostuid) which must be
  86                          * less that nsuid+(count) must not wrap around
  87                          */
  88                         return (in_id - hostuid) + nsuid;
  89                 }
  90         }
  91
  92         // no answer found
  93         return -1;
  94 }
  95
  96 static bool is_privileged_over(pid_t pid, uid_t uid, uid_t victim)
  97 {
  98         nih_local char *fpath = NULL;
  99         bool answer = false;
 100         uid_t nsuid;
 101
 102         if (uid == victim)
 103                 return true;
 104
 105         /* check /proc/pid/uid_map */
 106         fpath = NIH_MUST( nih_sprintf(NULL, "/proc/%d/uid_map", pid) );
 107         FILE *f = fopen(fpath, "r");
 108         if (!f)
 109                 return false;
 110
 111         nsuid = convert_id_to_ns(f, uid);
 112         if (nsuid)
 113                 goto out;
 114
 115         nsuid = convert_id_to_ns(f, victim);
 116         if (nsuid == -1)
 117                 goto out;
 118
 119         answer = true;
 120
 121 out:
 122         fclose(f);
 123         return answer;
 124 }
 125
 126 static bool perms_include(int fmode, mode_t req_mode)
 127 {
 128         mode_t r;
 129
 130         switch (req_mode & O_ACCMODE) {
 131         case O_RDONLY:
 132                 r = S_IROTH;
 133                 break;
 134         case O_WRONLY:
 135                 r = S_IWOTH;
 136                 break;
 137         case O_RDWR:
 138                 r = S_IROTH | S_IWOTH;
 139                 break;
 140         default:
 141                 return false;
 142         }
 143         return ((fmode & r) == r);
 144 }
 145
 146 /*
 147  * check whether a fuse context may access a cgroup dir or file
 148  *
 149  * If file is not null, it is a cgroup file to check under cg.
 150  * If file is null, then we are checking perms on cg itself.
 151  *
 152  * For files we can check the mode of the list_keys result.
 153  * For cgroups, we must make assumptions based on the files under the
 154  * cgroup, because cgmanager doesn't tell us ownership/perms of cgroups
 155  * yet.
 156  */
 157 static bool fc_may_access(struct fuse_context *fc, const char *contrl, const char *cg, const char *file, mode_t mode)
 158 {
 159         nih_local struct cgm_keys **list = NULL;
 160         int i;
 161
 162         if (!file)
 163                 file = "tasks";
 164
 165         if (*file == '/')
 166                 file++;
 167
 168         if (!cgm_list_keys(contrl, cg, &list))
 169                 return false;
 170         for (i = 0; list[i]; i++) {
 171                 if (strcmp(list[i]->name, file) == 0) {
 172                         struct cgm_keys *k = list[i];
 173                         if (is_privileged_over(fc->pid, fc->uid, k->uid)) {
 174                                 if (perms_include(k->mode >> 6, mode))
 175                                         return true;
 176                         }
 177                         if (fc->gid == k->gid) {
 178                                 if (perms_include(k->mode >> 3, mode))
 179                                         return true;
 180                         }
 181                         return perms_include(k->mode, mode);
 182                 }
 183         }
 184
 185         return false;
 186 }
 187
 188 /*
 189  * given /cgroup/freezer/a/b, return "freezer".  this will be nih-allocated
 190  * and needs to be nih_freed.
 191  */
 192 static char *pick_controller_from_path(struct fuse_context *fc, const char *path)
 193 {
 194         const char *p1;
 195         char *ret, *slash;
 196
 197         if (strlen(path) < 9)
 198                 return NULL;
 199         p1 = path+8;
 200         ret = nih_strdup(NULL, p1);
 201         if (!ret)
 202                 return ret;
 203         slash = strstr(ret, "/");
 204         if (slash)
 205                 *slash = '\0';
 206
 207         /* verify that it is a subsystem */
 208         char **list = LXCFS_DATA ? LXCFS_DATA->subsystems : NULL;
 209         int i;
 210         if (!list) {
 211                 nih_free(ret);
 212                 return NULL;
 213         }
 214         for (i = 0;  list[i];  i++) {
 215                 if (strcmp(list[i], ret) == 0)
 216                         return ret;
 217         }
 218         nih_free(ret);
 219         return NULL;
 220 }
 221
 222 /*
 223  * Find the start of cgroup in /cgroup/controller/the/cgroup/path
 224  * Note that the returned value may include files (keynames) etc
 225  */
 226 static const char *find_cgroup_in_path(const char *path)
 227 {
 228         const char *p1;
 229
 230         if (strlen(path) < 9)
 231                 return NULL;
 232         p1 = strstr(path+8, "/");
 233         if (!p1)
 234                 return NULL;
 235         return p1+1;
 236 }
 237
 238 static bool is_child_cgroup(const char *contr, const char *dir, const char *f)
 239 {
 240         nih_local char **list = NULL;
 241         int i;
 242
 243         if (!f)
 244                 return false;
 245         if (*f == '/')
 246                 f++;
 247
 248         if (!cgm_list_children(contr, dir, &list))
 249                 return false;
 250         for (i = 0; list[i]; i++) {
 251                 if (strcmp(list[i], f) == 0)
 252                         return true;
 253         }
 254
 255         return false;
 256 }
 257
 258 static struct cgm_keys *get_cgroup_key(const char *contr, const char *dir, const char *f)
 259 {
 260         nih_local struct cgm_keys **list = NULL;
 261         struct cgm_keys *k;
 262         int i;
 263
 264         if (!f)
 265                 return NULL;
 266         if (*f == '/')
 267                 f++;
 268         if (!cgm_list_keys(contr, dir, &list))
 269                 return NULL;
 270         for (i = 0; list[i]; i++) {
 271                 if (strcmp(list[i]->name, f) == 0) {
 272                         k = NIH_MUST( nih_alloc(NULL, (sizeof(*k))) );
 273                         k->name = NIH_MUST( nih_strdup(k, list[i]->name) );
 274                         k->uid = list[i]->uid;
 275                         k->gid = list[i]->gid;
 276                         k->mode = list[i]->mode;
 277                         return k;
 278                 }
 279         }
 280
 281         return NULL;
 282 }
 283
 284 static void get_cgdir_and_path(const char *cg, char **dir, char **file)
 285 {
 286         char *p;
 287
 288         *dir = NIH_MUST( nih_strdup(NULL, cg) );
 289         *file = strrchr(cg, '/');
 290         if (!*file) {
 291                 *file = NULL;
 292                 return;
 293         }
 294         p = strrchr(*dir, '/');
 295         *p = '\0';
 296 }
 297
 298 static size_t get_file_size(const char *contrl, const char *cg, const char *f)
 299 {
 300         nih_local char *data = NULL;
 301         size_t s;
 302         if (!cgm_get_value(contrl, cg, f, &data))
 303                 return -EINVAL;
 304         s = strlen(data);
 305         return s;
 306 }
 307
 308 /*
 309  * FUSE ops for /cgroup
 310  */
 311
 312 static int cg_getattr(const char *path, struct stat *sb)
 313 {
 314         struct timespec now;
 315         struct fuse_context *fc = fuse_get_context();
 316         nih_local char * cgdir = NULL;
 317         char *fpath = NULL, *path1, *path2;
 318         nih_local struct cgm_keys *k = NULL;
 319         const char *cgroup;
 320         nih_local char *controller = NULL;
 321
 322
 323         if (!fc)
 324                 return -EIO;
 325
 326         memset(sb, 0, sizeof(struct stat));
 327
 328         if (clock_gettime(CLOCK_REALTIME, &now) < 0)
 329                 return -EINVAL;
 330
 331         sb->st_uid = sb->st_gid = 0;
 332         sb->st_atim = sb->st_mtim = sb->st_ctim = now;
 333         sb->st_size = 0;
 334
 335         if (strcmp(path, "/cgroup") == 0) {
 336                 sb->st_mode = S_IFDIR | 00755;
 337                 sb->st_nlink = 2;
 338                 return 0;
 339         }
 340
 341         controller = pick_controller_from_path(fc, path);
 342         if (!controller)
 343                 return -EIO;
 344         cgroup = find_cgroup_in_path(path);
 345         if (!cgroup) {
 346                 /* this is just /cgroup/controller, return it as a dir */
 347                 sb->st_mode = S_IFDIR | 00755;
 348                 sb->st_nlink = 2;
 349                 return 0;
 350         }
 351
 352         get_cgdir_and_path(cgroup, &cgdir, &fpath);
 353
 354         if (!fpath) {
 355                 path1 = "/";
 356                 path2 = cgdir;
 357         } else {
 358                 path1 = cgdir;
 359                 path2 = fpath;
 360         }
 361
 362         /* check that cgcopy is either a child cgroup of cgdir, or listed in its keys.
 363          * Then check that caller's cgroup is under path if fpath is a child
 364          * cgroup, or cgdir if fpath is a file */
 365
 366         if (is_child_cgroup(controller, path1, path2)) {
 367                 if (!fc_may_access(fc, controller, cgroup, NULL, O_RDONLY))
 368                         return -EPERM;
 369
 370                 // get uid, gid, from '/tasks' file and make up a mode
 371                 // That is a hack, until cgmanager gains a GetCgroupPerms fn.
 372                 sb->st_mode = S_IFDIR | 00755;
 373                 k = get_cgroup_key(controller, cgroup, "tasks");
 374                 if (!k) {
 375                         fprintf(stderr, "Failed to find a tasks file for %s\n", cgroup);
 376                         sb->st_uid = sb->st_gid = 0;
 377                 } else {
 378                         fprintf(stderr, "found a tasks file for %s\n", cgroup);
 379                         sb->st_uid = k->uid;
 380                         sb->st_gid = k->gid;
 381                 }
 382                 sb->st_nlink = 2;
 383                 return 0;
 384         }
 385
 386         if ((k = get_cgroup_key(controller, path1, path2)) != NULL) {
 387                 if (!fc_may_access(fc, controller, path1, path2, O_RDONLY))
 388                         return -EPERM;
 389
 390                 sb->st_mode = S_IFREG | k->mode;
 391                 sb->st_nlink = 1;
 392                 sb->st_uid = k->uid;
 393                 sb->st_gid = k->gid;
 394                 sb->st_size = get_file_size(controller, path1, path2);
 395                 return 0;
 396         }
 397
 398         return -ENOENT;
 399 }
 400
 401 static int cg_opendir(const char *path, struct fuse_file_info *fi)
 402 {
 403         return 0;
 404 }
 405
 406 static int cg_readdir(const char *path, void *buf, fuse_fill_dir_t filler, off_t offset,
 407                 struct fuse_file_info *fi)
 408 {
 409         struct fuse_context *fc = fuse_get_context();
 410
 411         if (!fc)
 412                 return -EIO;
 413
 414         if (strcmp(path, "/cgroup") == 0) {
 415                 // get list of controllers
 416                 char **list = LXCFS_DATA ? LXCFS_DATA->subsystems : NULL;
 417                 int i;
 418
 419                 if (!list)
 420                         return -EIO;
 421                 /* TODO - collect the list of controllers at fuse_init */
 422                 for (i = 0;  list[i]; i++) {
 423                         if (filler(buf, list[i], NULL, 0) != 0) {
 424                                 return -EIO;
 425                         }
 426                 }
 427                 return 0;
 428         }
 429
 430         // return list of keys for the controller, and list of child cgroups
 431         nih_local struct cgm_keys **list = NULL;
 432         const char *cgroup;
 433         nih_local char *controller = NULL;
 434         int i;
 435
 436         controller = pick_controller_from_path(fc, path);
 437         if (!controller)
 438                 return -EIO;
 439
 440         cgroup = find_cgroup_in_path(path);
 441         if (!cgroup) {
 442                 /* this is just /cgroup/controller, return its contents */
 443                 cgroup = "/";
 444         }
 445
 446         if (!fc_may_access(fc, controller, cgroup, NULL, O_RDONLY))
 447                 return -EPERM;
 448
 449         if (!cgm_list_keys(controller, cgroup, &list))
 450                 return -EINVAL;
 451         for (i = 0; list[i]; i++) {
 452                 if (filler(buf, list[i]->name, NULL, 0) != 0) {
 453                         return -EIO;
 454                 }
 455         }
 456
 457         // now get the list of child cgroups
 458         nih_local char **clist;
 459
 460         if (!cgm_list_children(controller, cgroup, &clist))
 461                 return 0;
 462         for (i = 0; clist[i]; i++) {
 463                 if (filler(buf, clist[i], NULL, 0) != 0) {
 464                         return -EIO;
 465                 }
 466         }
 467         return 0;
 468 }
 469
 470 static int cg_releasedir(const char *path, struct fuse_file_info *fi)
 471 {
 472         return 0;
 473 }
 474
 475 static int cg_open(const char *path, struct fuse_file_info *fi)
 476 {
 477         nih_local char *controller = NULL;
 478         const char *cgroup;
 479         char *fpath = NULL, *path1, *path2;
 480         nih_local char * cgdir = NULL;
 481         nih_local struct cgm_keys *k = NULL;
 482         struct fuse_context *fc = fuse_get_context();
 483
 484         if (!fc)
 485                 return -EIO;
 486
 487         controller = pick_controller_from_path(fc, path);
 488         if (!controller)
 489                 return -EIO;
 490         cgroup = find_cgroup_in_path(path);
 491         if (!cgroup)
 492                 return -EINVAL;
 493
 494         get_cgdir_and_path(cgroup, &cgdir, &fpath);
 495         if (!fpath) {
 496                 path1 = "/";
 497                 path2 = cgdir;
 498         } else {
 499                 path1 = cgdir;
 500                 path2 = fpath;
 501         }
 502
 503         if ((k = get_cgroup_key(controller, path1, path2)) != NULL) {
 504                 if (!fc_may_access(fc, controller, path1, path2, fi->flags))
 505                         return -EPERM;
 506
 507                 /* TODO - we want to cache this info for read/write */
 508                 return 0;
 509         }
 510
 511         return -EINVAL;
 512 }
 513
 514 static int cg_read(const char *path, char *buf, size_t size, off_t offset,
 515                 struct fuse_file_info *fi)
 516 {
 517         nih_local char *controller = NULL;
 518         const char *cgroup;
 519         char *fpath = NULL, *path1, *path2;
 520         struct fuse_context *fc = fuse_get_context();
 521         nih_local char * cgdir = NULL;
 522         nih_local struct cgm_keys *k = NULL;
 523
 524         if (offset)
 525                 return -EIO;
 526
 527         if (!fc)
 528                 return -EIO;
 529
 530         controller = pick_controller_from_path(fc, path);
 531         if (!controller)
 532                 return -EIO;
 533         cgroup = find_cgroup_in_path(path);
 534         if (!cgroup)
 535                 return -EINVAL;
 536
 537         get_cgdir_and_path(cgroup, &cgdir, &fpath);
 538         if (!fpath) {
 539                 path1 = "/";
 540                 path2 = cgdir;
 541         } else {
 542                 path1 = cgdir;
 543                 path2 = fpath;
 544         }
 545
 546         if ((k = get_cgroup_key(controller, path1, path2)) != NULL) {
 547                 nih_local char *data = NULL;
 548                 int s;
 549
 550                 if (!fc_may_access(fc, controller, path1, path2, O_RDONLY))
 551                         return -EPERM;
 552
 553                 if (!cgm_get_value(controller, path1, path2, &data))
 554                         return -EINVAL;
 555
 556                 s = strlen(data);
 557                 if (s > size)
 558                         s = size;
 559                 memcpy(buf, data, s);
 560
 561                 return s;
 562         }
 563
 564         return -EINVAL;
 565 }
 566
 567 int cg_write(const char *path, const char *buf, size_t size, off_t offset,
 568              struct fuse_file_info *fi)
 569 {
 570         nih_local char *controller = NULL;
 571         const char *cgroup;
 572         char *fpath = NULL, *path1, *path2;
 573         struct fuse_context *fc = fuse_get_context();
 574         nih_local char * cgdir = NULL;
 575         nih_local struct cgm_keys *k = NULL;
 576
 577 fprintf(stderr, "cg_write: starting\n");
 578
 579         if (offset)
 580                 return -EIO;
 581
 582         if (!fc)
 583                 return -EIO;
 584
 585         controller = pick_controller_from_path(fc, path);
 586         if (!controller)
 587                 return -EIO;
 588         cgroup = find_cgroup_in_path(path);
 589         if (!cgroup)
 590                 return -EINVAL;
 591
 592         get_cgdir_and_path(cgroup, &cgdir, &fpath);
 593         if (!fpath) {
 594                 path1 = "/";
 595                 path2 = cgdir;
 596         } else {
 597                 path1 = cgdir;
 598                 path2 = fpath;
 599         }
 600
 601         if ((k = get_cgroup_key(controller, path1, path2)) != NULL) {
 602                 if (!fc_may_access(fc, controller, path1, path2, O_WRONLY))
 603                         return -EPERM;
 604
 605                 if (!cgm_set_value(controller, path1, path2, buf))
 606                         return -EINVAL;
 607
 608                 return size;
 609         }
 610
 611         return -EINVAL;
 612 }
 613
 614
 615 int cg_mkdir(const char *path, mode_t mode)
 616 {
 617         struct fuse_context *fc = fuse_get_context();
 618         nih_local struct cgm_keys **list = NULL;
 619         char *fpath = NULL, *path1;
 620         nih_local char * cgdir = NULL;
 621         const char *cgroup;
 622         nih_local char *controller = NULL;
 623
 624         if (!fc)
 625                 return -EIO;
 626
 627
 628         controller = pick_controller_from_path(fc, path);
 629         if (!controller)
 630                 return -EIO;
 631
 632         cgroup = find_cgroup_in_path(path);
 633         if (!cgroup)
 634                 return -EIO;
 635
 636         get_cgdir_and_path(cgroup, &cgdir, &fpath);
 637         if (!fpath)
 638                 path1 = "/";
 639         else
 640                 path1 = cgdir;
 641
 642         if (!fc_may_access(fc, controller, path1, NULL, O_RDWR))
 643                 return -EPERM;
 644
 645
 646         if (!cgm_create(controller, cgroup, fc->uid, fc->gid))
 647                 return -EINVAL;
 648
 649         return 0;
 650 }
 651
 652 /*
 653  * FUSE ops for /proc
 654  */
 655
 656 static int proc_getattr(const char *path, struct stat *sb)
 657 {
 658         if (strcmp(path, "/proc") != 0)
 659                 return -EINVAL;
 660         sb->st_mode = S_IFDIR | 00755;
 661         sb->st_nlink = 2;
 662         return 0;
 663 }
 664
 665 /*
 666  * FUSE ops for /
 667  * these just delegate to the /proc and /cgroup ops as
 668  * needed
 669  */
 670
 671 static int lxcfs_getattr(const char *path, struct stat *sb)
 672 {
 673         if (strcmp(path, "/") == 0) {
 674                 sb->st_mode = S_IFDIR | 00755;
 675                 sb->st_nlink = 2;
 676                 return 0;
 677         }
 678         if (strncmp(path, "/cgroup", 7) == 0) {
 679                 return cg_getattr(path, sb);
 680         }
 681         if (strncmp(path, "/proc", 7) == 0) {
 682                 return proc_getattr(path, sb);
 683         }
 684         return -EINVAL;
 685 }
 686
 687 static int lxcfs_opendir(const char *path, struct fuse_file_info *fi)
 688 {
 689         if (strcmp(path, "/") == 0)
 690                 return 0;
 691
 692         if (strncmp(path, "/cgroup", 7) == 0) {
 693                 return cg_opendir(path, fi);
 694         }
 695         return -EINVAL;
 696 }
 697
 698 static int lxcfs_readdir(const char *path, void *buf, fuse_fill_dir_t filler, off_t offset,
 699                 struct fuse_file_info *fi)
 700 {
 701         if (strcmp(path, "/") == 0) {
 702                 if (filler(buf, "proc", NULL, 0) != 0 ||
 703                                 filler(buf, "cgroup", NULL, 0) != 0)
 704                         return -EINVAL;
 705                 return 0;
 706         }
 707         if (strncmp(path, "/cgroup", 7) == 0) {
 708                 return cg_readdir(path, buf, filler, offset, fi);
 709         }
 710         return -EINVAL;
 711 }
 712
 713 static int lxcfs_releasedir(const char *path, struct fuse_file_info *fi)
 714 {
 715         if (strcmp(path, "/") == 0)
 716                 return 0;
 717         if (strncmp(path, "/cgroup", 7) == 0) {
 718                 return cg_releasedir(path, fi);
 719         }
 720         return -EINVAL;
 721 }
 722
 723 static int lxcfs_open(const char *path, struct fuse_file_info *fi)
 724 {
 725         if (strncmp(path, "/cgroup", 7) == 0) {
 726                 return cg_open(path, fi);
 727         }
 728
 729         return -EINVAL;
 730 }
 731
 732 static int lxcfs_read(const char *path, char *buf, size_t size, off_t offset,
 733                 struct fuse_file_info *fi)
 734 {
 735         if (strncmp(path, "/cgroup", 7) == 0) {
 736                 return cg_read(path, buf, size, offset, fi);
 737         }
 738
 739         return -EINVAL;
 740 }
 741
 742 int lxcfs_write(const char *path, const char *buf, size_t size, off_t offset,
 743              struct fuse_file_info *fi)
 744 {
 745         if (strncmp(path, "/cgroup", 7) == 0) {
 746                 return cg_write(path, buf, size, offset, fi);
 747         }
 748
 749         return -EINVAL;
 750 }
 751
 752 static int lxcfs_flush(const char *path, struct fuse_file_info *fi)
 753 {
 754         return 0;
 755 }
 756
 757 static int lxcfs_release(const char *path, struct fuse_file_info *fi)
 758 {
 759         return 0;
 760 }
 761
 762 static int lxcfs_fsync(const char *path, int datasync, struct fuse_file_info *fi)
 763 {
 764         return 0;
 765 }
 766
 767 int lxcfs_mkdir(const char *path, mode_t mode)
 768 {
 769         if (strncmp(path, "/cgroup", 7) == 0)
 770                 return cg_mkdir(path, mode);
 771
 772         return -EINVAL;
 773 }
 774
 775 /*
 776  * cat first does a truncate before doing ops->write.  This doesn't
 777  * really make sense for cgroups.  So just return 0 always but do
 778  * nothing.
 779  */
 780 int lxcfs_truncate(const char *path, off_t newsize)
 781 {
 782         if (strncmp(path, "/cgroup", 7) == 0)
 783                 return 0;
 784         return -EINVAL;
 785 }
 786
 787 const struct fuse_operations lxcfs_ops = {
 788         .getattr = lxcfs_getattr,
 789         .readlink = NULL,
 790         .getdir = NULL,
 791         .mknod = NULL,
 792         .mkdir = lxcfs_mkdir,
 793         .unlink = NULL,
 794         .rmdir = NULL,
 795         .symlink = NULL,
 796         .rename = NULL,
 797         .link = NULL,
 798         .chmod = NULL,
 799         .chown = NULL,
 800         .truncate = lxcfs_truncate,
 801         .utime = NULL,
 802
 803         .open = lxcfs_open,
 804         .read = lxcfs_read,
 805         .release = lxcfs_release,
 806         .write = lxcfs_write,
 807
 808         .statfs = NULL,
 809         .flush = lxcfs_flush,
 810         .fsync = lxcfs_fsync,
 811
 812         .setxattr = NULL,
 813         .getxattr = NULL,
 814         .listxattr = NULL,
 815         .removexattr = NULL,
 816
 817         .opendir = lxcfs_opendir,
 818         .readdir = lxcfs_readdir,
 819         .releasedir = lxcfs_releasedir,
 820
 821         .fsyncdir = NULL,
 822         .init = NULL,
 823         .destroy = NULL,
 824         .access = NULL,
 825         .create = NULL,
 826         .ftruncate = NULL,
 827         .fgetattr = NULL,
 828 };
 829
 830 static void usage(const char *me)
 831 {
 832         fprintf(stderr, "Usage:\n");
 833         fprintf(stderr, "\n");
 834         fprintf(stderr, "%s [FUSE and mount options] mountpoint\n", me);
 835         exit(1);
 836 }
 837
 838 static bool is_help(char *w)
 839 {
 840         if (strcmp(w, "-h") == 0 ||
 841                         strcmp(w, "--help") == 0 ||
 842                         strcmp(w, "-help") == 0 ||
 843                         strcmp(w, "help") == 0)
 844                 return true;
 845         return false;
 846 }
 847
 848 int main(int argc, char *argv[])
 849 {
 850         int ret;
 851         struct lxcfs_state *d;
 852
 853         if (argc < 2 || is_help(argv[1]))
 854                 usage(argv[0]);
 855
 856         d = malloc(sizeof(*d));
 857         if (!d)
 858                 return -1;
 859
 860         if (!cgm_escape_cgroup())
 861                 fprintf(stderr, "WARNING: failed to escape to root cgroup\n");
 862
 863         if (!cgm_get_controllers(&d->subsystems))
 864                 return -1;
 865
 866         ret = fuse_main(argc, argv, &lxcfs_ops, d);
 867
 868         return ret;
 869 }