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   1 /*
   2   FUSE: Filesystem in Userspace
   3   Copyright (C) 2001-2005  Miklos Szeredi <miklos@szeredi.hu>
   4
   5   This program can be distributed under the terms of the GNU GPL.
   6   See the file COPYING.
   7 */
   8
   9 #include "fuse_i.h"
  10
  11 #include <linux/pagemap.h>
  12 #include <linux/slab.h>
  13 #include <linux/file.h>
  14 #include <linux/mount.h>
  15 #include <linux/seq_file.h>
  16 #include <linux/init.h>
  17 #include <linux/module.h>
  18 #include <linux/moduleparam.h>
  19 #include <linux/parser.h>
  20 #include <linux/statfs.h>
  21
  22 MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
  23 MODULE_DESCRIPTION("Filesystem in Userspace");
  24 MODULE_LICENSE("GPL");
  25
  26 spinlock_t fuse_lock;
  27 static kmem_cache_t *fuse_inode_cachep;
  28 static int mount_count;
  29
  30 static int mount_max = 1000;
  31 module_param(mount_max, int, 0644);
  32 MODULE_PARM_DESC(mount_max, "Maximum number of FUSE mounts allowed, if -1 then unlimited (default: 1000)");
  33
  34 #define FUSE_SUPER_MAGIC 0x65735546
  35
  36 struct fuse_mount_data {
  37         int fd;
  38         unsigned rootmode;
  39         unsigned user_id;
  40 };
  41
  42 static struct inode *fuse_alloc_inode(struct super_block *sb)
  43 {
  44         struct inode *inode;
  45         struct fuse_inode *fi;
  46
  47         inode = kmem_cache_alloc(fuse_inode_cachep, SLAB_KERNEL);
  48         if (!inode)
  49                 return NULL;
  50
  51         fi = get_fuse_inode(inode);
  52         fi->i_time = jiffies - 1;
  53         fi->nodeid = 0;
  54         fi->nlookup = 0;
  55         fi->forget_req = fuse_request_alloc();
  56         if (!fi->forget_req) {
  57                 kmem_cache_free(fuse_inode_cachep, inode);
  58                 return NULL;
  59         }
  60
  61         return inode;
  62 }
  63
  64 static void fuse_destroy_inode(struct inode *inode)
  65 {
  66         struct fuse_inode *fi = get_fuse_inode(inode);
  67         if (fi->forget_req)
  68                 fuse_request_free(fi->forget_req);
  69         kmem_cache_free(fuse_inode_cachep, inode);
  70 }
  71
  72 static void fuse_read_inode(struct inode *inode)
  73 {
  74         /* No op */
  75 }
  76
  77 void fuse_send_forget(struct fuse_conn *fc, struct fuse_req *req,
  78                       unsigned long nodeid, u64 nlookup)
  79 {
  80         struct fuse_forget_in *inarg = &req->misc.forget_in;
  81         inarg->nlookup = nlookup;
  82         req->in.h.opcode = FUSE_FORGET;
  83         req->in.h.nodeid = nodeid;
  84         req->in.numargs = 1;
  85         req->in.args[0].size = sizeof(struct fuse_forget_in);
  86         req->in.args[0].value = inarg;
  87         request_send_noreply(fc, req);
  88 }
  89
  90 static void fuse_clear_inode(struct inode *inode)
  91 {
  92         struct fuse_conn *fc = get_fuse_conn(inode);
  93         if (fc) {
  94                 struct fuse_inode *fi = get_fuse_inode(inode);
  95                 fuse_send_forget(fc, fi->forget_req, fi->nodeid, fi->nlookup);
  96                 fi->forget_req = NULL;
  97         }
  98 }
  99
 100 void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr)
 101 {
 102         if (S_ISREG(inode->i_mode) && i_size_read(inode) != attr->size)
 103                 invalidate_inode_pages(inode->i_mapping);
 104
 105         inode->i_ino     = attr->ino;
 106         inode->i_mode    = (inode->i_mode & S_IFMT) + (attr->mode & 07777);
 107         inode->i_nlink   = attr->nlink;
 108         inode->i_uid     = attr->uid;
 109         inode->i_gid     = attr->gid;
 110         i_size_write(inode, attr->size);
 111         inode->i_blksize = PAGE_CACHE_SIZE;
 112         inode->i_blocks  = attr->blocks;
 113         inode->i_atime.tv_sec   = attr->atime;
 114         inode->i_atime.tv_nsec  = attr->atimensec;
 115         inode->i_mtime.tv_sec   = attr->mtime;
 116         inode->i_mtime.tv_nsec  = attr->mtimensec;
 117         inode->i_ctime.tv_sec   = attr->ctime;
 118         inode->i_ctime.tv_nsec  = attr->ctimensec;
 119 }
 120
 121 static void fuse_init_inode(struct inode *inode, struct fuse_attr *attr)
 122 {
 123         inode->i_mode = attr->mode & S_IFMT;
 124         i_size_write(inode, attr->size);
 125         if (S_ISREG(inode->i_mode)) {
 126                 fuse_init_common(inode);
 127                 fuse_init_file_inode(inode);
 128         } else if (S_ISDIR(inode->i_mode))
 129                 fuse_init_dir(inode);
 130         else if (S_ISLNK(inode->i_mode))
 131                 fuse_init_symlink(inode);
 132         else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
 133                  S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
 134                 fuse_init_common(inode);
 135                 init_special_inode(inode, inode->i_mode,
 136                                    new_decode_dev(attr->rdev));
 137         } else {
 138                 /* Don't let user create weird files */
 139                 inode->i_mode = S_IFREG;
 140                 fuse_init_common(inode);
 141                 fuse_init_file_inode(inode);
 142         }
 143 }
 144
 145 static int fuse_inode_eq(struct inode *inode, void *_nodeidp)
 146 {
 147         unsigned long nodeid = *(unsigned long *) _nodeidp;
 148         if (get_node_id(inode) == nodeid)
 149                 return 1;
 150         else
 151                 return 0;
 152 }
 153
 154 static int fuse_inode_set(struct inode *inode, void *_nodeidp)
 155 {
 156         unsigned long nodeid = *(unsigned long *) _nodeidp;
 157         get_fuse_inode(inode)->nodeid = nodeid;
 158         return 0;
 159 }
 160
 161 struct inode *fuse_iget(struct super_block *sb, unsigned long nodeid,
 162                         int generation, struct fuse_attr *attr)
 163 {
 164         struct inode *inode;
 165         struct fuse_inode *fi;
 166         struct fuse_conn *fc = get_fuse_conn_super(sb);
 167         int retried = 0;
 168
 169  retry:
 170         inode = iget5_locked(sb, nodeid, fuse_inode_eq, fuse_inode_set, &nodeid);
 171         if (!inode)
 172                 return NULL;
 173
 174         if ((inode->i_state & I_NEW)) {
 175                 inode->i_generation = generation;
 176                 inode->i_data.backing_dev_info = &fc->bdi;
 177                 fuse_init_inode(inode, attr);
 178                 unlock_new_inode(inode);
 179         } else if ((inode->i_mode ^ attr->mode) & S_IFMT) {
 180                 BUG_ON(retried);
 181                 /* Inode has changed type, any I/O on the old should fail */
 182                 make_bad_inode(inode);
 183                 iput(inode);
 184                 retried = 1;
 185                 goto retry;
 186         }
 187
 188         fi = get_fuse_inode(inode);
 189         fi->nlookup ++;
 190         fuse_change_attributes(inode, attr);
 191         return inode;
 192 }
 193
 194 static void fuse_put_super(struct super_block *sb)
 195 {
 196         struct fuse_conn *fc = get_fuse_conn_super(sb);
 197
 198         spin_lock(&fuse_lock);
 199         mount_count --;
 200         fc->sb = NULL;
 201         fc->user_id = 0;
 202         /* Flush all readers on this fs */
 203         wake_up_all(&fc->waitq);
 204         fuse_release_conn(fc);
 205         *get_fuse_conn_super_p(sb) = NULL;
 206         spin_unlock(&fuse_lock);
 207 }
 208
 209 static void convert_fuse_statfs(struct kstatfs *stbuf, struct fuse_kstatfs *attr)
 210 {
 211         stbuf->f_type    = FUSE_SUPER_MAGIC;
 212         stbuf->f_bsize   = attr->bsize;
 213         stbuf->f_blocks  = attr->blocks;
 214         stbuf->f_bfree   = attr->bfree;
 215         stbuf->f_bavail  = attr->bavail;
 216         stbuf->f_files   = attr->files;
 217         stbuf->f_ffree   = attr->ffree;
 218         stbuf->f_namelen = attr->namelen;
 219         /* fsid is left zero */
 220 }
 221
 222 static int fuse_statfs(struct super_block *sb, struct kstatfs *buf)
 223 {
 224         struct fuse_conn *fc = get_fuse_conn_super(sb);
 225         struct fuse_req *req;
 226         struct fuse_statfs_out outarg;
 227         int err;
 228
 229         req = fuse_get_request(fc);
 230         if (!req)
 231                 return -ERESTARTSYS;
 232
 233         req->in.numargs = 0;
 234         req->in.h.opcode = FUSE_STATFS;
 235         req->out.numargs = 1;
 236         req->out.args[0].size = sizeof(outarg);
 237         req->out.args[0].value = &outarg;
 238         request_send(fc, req);
 239         err = req->out.h.error;
 240         if (!err)
 241                 convert_fuse_statfs(buf, &outarg.st);
 242         fuse_put_request(fc, req);
 243         return err;
 244 }
 245
 246 enum {
 247         OPT_FD,
 248         OPT_ROOTMODE,
 249         OPT_USER_ID,
 250         OPT_DEFAULT_PERMISSIONS,
 251         OPT_ALLOW_OTHER,
 252         OPT_ALLOW_ROOT,
 253         OPT_KERNEL_CACHE,
 254         OPT_ERR
 255 };
 256
 257 static match_table_t tokens = {
 258         {OPT_FD,                        "fd=%u"},
 259         {OPT_ROOTMODE,                  "rootmode=%o"},
 260         {OPT_USER_ID,                   "user_id=%u"},
 261         {OPT_DEFAULT_PERMISSIONS,       "default_permissions"},
 262         {OPT_ALLOW_OTHER,               "allow_other"},
 263         {OPT_ALLOW_ROOT,                "allow_root"},
 264         {OPT_KERNEL_CACHE,              "kernel_cache"},
 265         {OPT_ERR,                       NULL}
 266 };
 267
 268 static int parse_fuse_opt(char *opt, struct fuse_mount_data *d)
 269 {
 270         char *p;
 271         memset(d, 0, sizeof(struct fuse_mount_data));
 272         d->fd = -1;
 273
 274         while ((p = strsep(&opt, ",")) != NULL) {
 275                 int token;
 276                 int value;
 277                 substring_t args[MAX_OPT_ARGS];
 278                 if (!*p)
 279                         continue;
 280
 281                 token = match_token(p, tokens, args);
 282                 switch (token) {
 283                 case OPT_FD:
 284                         if (match_int(&args[0], &value))
 285                                 return 0;
 286                         d->fd = value;
 287                         break;
 288
 289                 case OPT_ROOTMODE:
 290                         if (match_octal(&args[0], &value))
 291                                 return 0;
 292                         d->rootmode = value;
 293                         break;
 294
 295                 case OPT_USER_ID:
 296                         if (match_int(&args[0], &value))
 297                                 return 0;
 298                         d->user_id = value;
 299                         break;
 300
 301                 default:
 302                         return 0;
 303                 }
 304         }
 305         if (d->fd == -1)
 306                 return 0;
 307
 308         return 1;
 309 }
 310
 311 static int fuse_show_options(struct seq_file *m, struct vfsmount *mnt)
 312 {
 313         struct fuse_conn *fc = get_fuse_conn_super(mnt->mnt_sb);
 314
 315         seq_printf(m, ",user_id=%u", fc->user_id);
 316         return 0;
 317 }
 318
 319 static void free_conn(struct fuse_conn *fc)
 320 {
 321         while (!list_empty(&fc->unused_list)) {
 322                 struct fuse_req *req;
 323                 req = list_entry(fc->unused_list.next, struct fuse_req, list);
 324                 list_del(&req->list);
 325                 fuse_request_free(req);
 326         }
 327         kfree(fc);
 328 }
 329
 330 /* Must be called with the fuse lock held */
 331 void fuse_release_conn(struct fuse_conn *fc)
 332 {
 333         if (!fc->sb && !fc->file)
 334                 free_conn(fc);
 335 }
 336
 337 static struct fuse_conn *new_conn(void)
 338 {
 339         struct fuse_conn *fc;
 340
 341         fc = kmalloc(sizeof(*fc), GFP_KERNEL);
 342         if (fc != NULL) {
 343                 int i;
 344                 memset(fc, 0, sizeof(*fc));
 345                 fc->sb = NULL;
 346                 fc->file = NULL;
 347                 fc->user_id = 0;
 348                 init_waitqueue_head(&fc->waitq);
 349                 INIT_LIST_HEAD(&fc->pending);
 350                 INIT_LIST_HEAD(&fc->processing);
 351                 INIT_LIST_HEAD(&fc->unused_list);
 352                 sema_init(&fc->outstanding_sem, 0);
 353                 for (i = 0; i < FUSE_MAX_OUTSTANDING; i++) {
 354                         struct fuse_req *req = fuse_request_alloc();
 355                         if (!req) {
 356                                 free_conn(fc);
 357                                 return NULL;
 358                         }
 359                         list_add(&req->list, &fc->unused_list);
 360                 }
 361                 fc->bdi.ra_pages = (VM_MAX_READAHEAD * 1024) / PAGE_CACHE_SIZE;
 362                 fc->bdi.unplug_io_fn = default_unplug_io_fn;
 363                 fc->reqctr = 0;
 364         }
 365         return fc;
 366 }
 367
 368 static struct fuse_conn *get_conn(struct file *file, struct super_block *sb)
 369 {
 370         struct fuse_conn *fc;
 371
 372         if (file->f_op != &fuse_dev_operations)
 373                 return ERR_PTR(-EINVAL);
 374         fc = new_conn();
 375         if (fc == NULL)
 376                 return ERR_PTR(-ENOMEM);
 377         spin_lock(&fuse_lock);
 378         if (file->private_data) {
 379                 free_conn(fc);
 380                 fc = ERR_PTR(-EINVAL);
 381         } else {
 382                 file->private_data = fc;
 383                 fc->sb = sb;
 384                 fc->file = file;
 385         }
 386         spin_unlock(&fuse_lock);
 387         return fc;
 388 }
 389
 390 static struct inode *get_root_inode(struct super_block *sb, unsigned mode)
 391 {
 392         struct fuse_attr attr;
 393         memset(&attr, 0, sizeof(attr));
 394
 395         attr.mode = mode;
 396         attr.ino = FUSE_ROOT_ID;
 397         return fuse_iget(sb, 1, 0, &attr);
 398 }
 399
 400 static struct super_operations fuse_super_operations = {
 401         .alloc_inode    = fuse_alloc_inode,
 402         .destroy_inode  = fuse_destroy_inode,
 403         .read_inode     = fuse_read_inode,
 404         .clear_inode    = fuse_clear_inode,
 405         .put_super      = fuse_put_super,
 406         .statfs         = fuse_statfs,
 407         .show_options   = fuse_show_options,
 408 };
 409
 410 static int inc_mount_count(void)
 411 {
 412         int success = 0;
 413         spin_lock(&fuse_lock);
 414         mount_count ++;
 415         if (mount_max == -1 || mount_count <= mount_max)
 416                 success = 1;
 417         spin_unlock(&fuse_lock);
 418         return success;
 419 }
 420
 421 static int fuse_fill_super(struct super_block *sb, void *data, int silent)
 422 {
 423         struct fuse_conn *fc;
 424         struct inode *root;
 425         struct fuse_mount_data d;
 426         struct file *file;
 427         int err;
 428
 429         if (!parse_fuse_opt((char *) data, &d))
 430                 return -EINVAL;
 431
 432         sb->s_blocksize = PAGE_CACHE_SIZE;
 433         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 434         sb->s_magic = FUSE_SUPER_MAGIC;
 435         sb->s_op = &fuse_super_operations;
 436         sb->s_maxbytes = MAX_LFS_FILESIZE;
 437
 438         file = fget(d.fd);
 439         if (!file)
 440                 return -EINVAL;
 441
 442         fc = get_conn(file, sb);
 443         fput(file);
 444         if (IS_ERR(fc))
 445                 return PTR_ERR(fc);
 446
 447         fc->user_id = d.user_id;
 448
 449         *get_fuse_conn_super_p(sb) = fc;
 450
 451         err = -ENFILE;
 452         if (!inc_mount_count() && current->uid != 0)
 453                 goto err;
 454
 455         err = -ENOMEM;
 456         root = get_root_inode(sb, d.rootmode);
 457         if (root == NULL)
 458                 goto err;
 459
 460         sb->s_root = d_alloc_root(root);
 461         if (!sb->s_root) {
 462                 iput(root);
 463                 goto err;
 464         }
 465         fuse_send_init(fc);
 466         return 0;
 467
 468  err:
 469         spin_lock(&fuse_lock);
 470         mount_count --;
 471         fc->sb = NULL;
 472         fuse_release_conn(fc);
 473         spin_unlock(&fuse_lock);
 474         *get_fuse_conn_super_p(sb) = NULL;
 475         return err;
 476 }
 477
 478 static struct super_block *fuse_get_sb(struct file_system_type *fs_type,
 479                                        int flags, const char *dev_name,
 480                                        void *raw_data)
 481 {
 482         return get_sb_nodev(fs_type, flags, raw_data, fuse_fill_super);
 483 }
 484
 485 static struct file_system_type fuse_fs_type = {
 486         .owner          = THIS_MODULE,
 487         .name           = "fuse",
 488         .get_sb         = fuse_get_sb,
 489         .kill_sb        = kill_anon_super,
 490 };
 491
 492 static void fuse_inode_init_once(void *foo, kmem_cache_t *cachep,
 493                                  unsigned long flags)
 494 {
 495         struct inode * inode = foo;
 496
 497         if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
 498             SLAB_CTOR_CONSTRUCTOR)
 499                 inode_init_once(inode);
 500 }
 501
 502 static int __init fuse_fs_init(void)
 503 {
 504         int err;
 505
 506         err = register_filesystem(&fuse_fs_type);
 507         if (err)
 508                 printk("fuse: failed to register filesystem\n");
 509         else {
 510                 fuse_inode_cachep = kmem_cache_create("fuse_inode",
 511                                                       sizeof(struct fuse_inode),
 512                                                       0, SLAB_HWCACHE_ALIGN,
 513                                                       fuse_inode_init_once, NULL);
 514                 if (!fuse_inode_cachep) {
 515                         unregister_filesystem(&fuse_fs_type);
 516                         err = -ENOMEM;
 517                 }
 518         }
 519
 520         return err;
 521 }
 522
 523 static void fuse_fs_cleanup(void)
 524 {
 525         unregister_filesystem(&fuse_fs_type);
 526         kmem_cache_destroy(fuse_inode_cachep);
 527 }
 528
 529 static int __init fuse_init(void)
 530 {
 531         int res;
 532
 533         printk("fuse init (API version %i.%i)\n",
 534                FUSE_KERNEL_VERSION, FUSE_KERNEL_MINOR_VERSION);
 535
 536         spin_lock_init(&fuse_lock);
 537         res = fuse_fs_init();
 538         if (res)
 539                 goto err;
 540
 541         res = fuse_dev_init();
 542         if (res)
 543                 goto err_fs_cleanup;
 544
 545         return 0;
 546
 547  err_fs_cleanup:
 548         fuse_fs_cleanup();
 549  err:
 550         return res;
 551 }
 552
 553 static void __exit fuse_exit(void)
 554 {
 555         printk(KERN_DEBUG "fuse exit\n");
 556
 557         fuse_fs_cleanup();
 558         fuse_dev_cleanup();
 559 }
 560
 561 module_init(fuse_init);
 562 module_exit(fuse_exit);