fs/autofs/inode.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
   4  * Copyright 2005-2006 Ian Kent <raven@themaw.net>
   5  */
   6
   7 #include <linux/seq_file.h>
   8 #include <linux/pagemap.h>
   9
  10 #include "autofs_i.h"
  11
  12 struct autofs_info *autofs_new_ino(struct autofs_sb_info *sbi)
  13 {
  14         struct autofs_info *ino;
  15
  16         ino = kzalloc(sizeof(*ino), GFP_KERNEL);
  17         if (ino) {
  18                 INIT_LIST_HEAD(&ino->active);
  19                 INIT_LIST_HEAD(&ino->expiring);
  20                 ino->last_used = jiffies;
  21                 ino->sbi = sbi;
  22                 ino->exp_timeout = -1;
  23                 ino->count = 1;
  24         }
  25         return ino;
  26 }
  27
  28 void autofs_clean_ino(struct autofs_info *ino)
  29 {
  30         ino->uid = GLOBAL_ROOT_UID;
  31         ino->gid = GLOBAL_ROOT_GID;
  32         ino->exp_timeout = -1;
  33         ino->last_used = jiffies;
  34 }
  35
  36 void autofs_free_ino(struct autofs_info *ino)
  37 {
  38         kfree_rcu(ino, rcu);
  39 }
  40
  41 void autofs_kill_sb(struct super_block *sb)
  42 {
  43         struct autofs_sb_info *sbi = autofs_sbi(sb);
  44
  45         /*
  46          * In the event of a failure in get_sb_nodev the superblock
  47          * info is not present so nothing else has been setup, so
  48          * just call kill_anon_super when we are called from
  49          * deactivate_super.
  50          */
  51         if (sbi) {
  52                 /* Free wait queues, close pipe */
  53                 autofs_catatonic_mode(sbi);
  54                 put_pid(sbi->oz_pgrp);
  55         }
  56
  57         pr_debug("shutting down\n");
  58         kill_litter_super(sb);
  59         if (sbi)
  60                 kfree_rcu(sbi, rcu);
  61 }
  62
  63 static int autofs_show_options(struct seq_file *m, struct dentry *root)
  64 {
  65         struct autofs_sb_info *sbi = autofs_sbi(root->d_sb);
  66         struct inode *root_inode = d_inode(root->d_sb->s_root);
  67
  68         if (!sbi)
  69                 return 0;
  70
  71         seq_printf(m, ",fd=%d", sbi->pipefd);
  72         if (!uid_eq(root_inode->i_uid, GLOBAL_ROOT_UID))
  73                 seq_printf(m, ",uid=%u",
  74                         from_kuid_munged(&init_user_ns, root_inode->i_uid));
  75         if (!gid_eq(root_inode->i_gid, GLOBAL_ROOT_GID))
  76                 seq_printf(m, ",gid=%u",
  77                         from_kgid_munged(&init_user_ns, root_inode->i_gid));
  78         seq_printf(m, ",pgrp=%d", pid_vnr(sbi->oz_pgrp));
  79         seq_printf(m, ",timeout=%lu", sbi->exp_timeout/HZ);
  80         seq_printf(m, ",minproto=%d", sbi->min_proto);
  81         seq_printf(m, ",maxproto=%d", sbi->max_proto);
  82
  83         if (autofs_type_offset(sbi->type))
  84                 seq_puts(m, ",offset");
  85         else if (autofs_type_direct(sbi->type))
  86                 seq_puts(m, ",direct");
  87         else
  88                 seq_puts(m, ",indirect");
  89         if (sbi->flags & AUTOFS_SBI_STRICTEXPIRE)
  90                 seq_puts(m, ",strictexpire");
  91         if (sbi->flags & AUTOFS_SBI_IGNORE)
  92                 seq_puts(m, ",ignore");
  93 #ifdef CONFIG_CHECKPOINT_RESTORE
  94         if (sbi->pipe)
  95                 seq_printf(m, ",pipe_ino=%ld", file_inode(sbi->pipe)->i_ino);
  96         else
  97                 seq_puts(m, ",pipe_ino=-1");
  98 #endif
  99         return 0;
 100 }
 101
 102 static void autofs_evict_inode(struct inode *inode)
 103 {
 104         clear_inode(inode);
 105         kfree(inode->i_private);
 106 }
 107
 108 static const struct super_operations autofs_sops = {
 109         .statfs         = simple_statfs,
 110         .show_options   = autofs_show_options,
 111         .evict_inode    = autofs_evict_inode,
 112 };
 113
 114 enum {
 115         Opt_direct,
 116         Opt_fd,
 117         Opt_gid,
 118         Opt_ignore,
 119         Opt_indirect,
 120         Opt_maxproto,
 121         Opt_minproto,
 122         Opt_offset,
 123         Opt_pgrp,
 124         Opt_strictexpire,
 125         Opt_uid,
 126 };
 127
 128 const struct fs_parameter_spec autofs_param_specs[] = {
 129         fsparam_flag    ("direct",              Opt_direct),
 130         fsparam_fd      ("fd",                  Opt_fd),
 131         fsparam_gid     ("gid",                 Opt_gid),
 132         fsparam_flag    ("ignore",              Opt_ignore),
 133         fsparam_flag    ("indirect",            Opt_indirect),
 134         fsparam_u32     ("maxproto",            Opt_maxproto),
 135         fsparam_u32     ("minproto",            Opt_minproto),
 136         fsparam_flag    ("offset",              Opt_offset),
 137         fsparam_u32     ("pgrp",                Opt_pgrp),
 138         fsparam_flag    ("strictexpire",        Opt_strictexpire),
 139         fsparam_uid     ("uid",                 Opt_uid),
 140         {}
 141 };
 142
 143 struct autofs_fs_context {
 144         kuid_t  uid;
 145         kgid_t  gid;
 146         int     pgrp;
 147         bool    pgrp_set;
 148 };
 149
 150 /*
 151  * Open the fd.  We do it here rather than in get_tree so that it's done in the
 152  * context of the system call that passed the data and not the one that
 153  * triggered the superblock creation, lest the fd gets reassigned.
 154  */
 155 static int autofs_parse_fd(struct fs_context *fc, struct autofs_sb_info *sbi,
 156                            struct fs_parameter *param,
 157                            struct fs_parse_result *result)
 158 {
 159         struct file *pipe;
 160         int ret;
 161
 162         if (param->type == fs_value_is_file) {
 163                 /* came through the new api */
 164                 pipe = param->file;
 165                 param->file = NULL;
 166         } else {
 167                 pipe = fget(result->uint_32);
 168         }
 169         if (!pipe) {
 170                 errorf(fc, "could not open pipe file descriptor");
 171                 return -EBADF;
 172         }
 173
 174         ret = autofs_check_pipe(pipe);
 175         if (ret < 0) {
 176                 errorf(fc, "Invalid/unusable pipe");
 177                 fput(pipe);
 178                 return -EBADF;
 179         }
 180
 181         autofs_set_packet_pipe_flags(pipe);
 182
 183         if (sbi->pipe)
 184                 fput(sbi->pipe);
 185
 186         sbi->pipefd = result->uint_32;
 187         sbi->pipe = pipe;
 188
 189         return 0;
 190 }
 191
 192 static int autofs_parse_param(struct fs_context *fc, struct fs_parameter *param)
 193 {
 194         struct autofs_fs_context *ctx = fc->fs_private;
 195         struct autofs_sb_info *sbi = fc->s_fs_info;
 196         struct fs_parse_result result;
 197         int opt;
 198
 199         opt = fs_parse(fc, autofs_param_specs, param, &result);
 200         if (opt < 0)
 201                 return opt;
 202
 203         switch (opt) {
 204         case Opt_fd:
 205                 return autofs_parse_fd(fc, sbi, param, &result);
 206         case Opt_uid:
 207                 ctx->uid = result.uid;
 208                 break;
 209         case Opt_gid:
 210                 ctx->gid = result.gid;
 211                 break;
 212         case Opt_pgrp:
 213                 ctx->pgrp = result.uint_32;
 214                 ctx->pgrp_set = true;
 215                 break;
 216         case Opt_minproto:
 217                 sbi->min_proto = result.uint_32;
 218                 break;
 219         case Opt_maxproto:
 220                 sbi->max_proto = result.uint_32;
 221                 break;
 222         case Opt_indirect:
 223                 set_autofs_type_indirect(&sbi->type);
 224                 break;
 225         case Opt_direct:
 226                 set_autofs_type_direct(&sbi->type);
 227                 break;
 228         case Opt_offset:
 229                 set_autofs_type_offset(&sbi->type);
 230                 break;
 231         case Opt_strictexpire:
 232                 sbi->flags |= AUTOFS_SBI_STRICTEXPIRE;
 233                 break;
 234         case Opt_ignore:
 235                 sbi->flags |= AUTOFS_SBI_IGNORE;
 236         }
 237
 238         return 0;
 239 }
 240
 241 static struct autofs_sb_info *autofs_alloc_sbi(void)
 242 {
 243         struct autofs_sb_info *sbi;
 244
 245         sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
 246         if (!sbi)
 247                 return NULL;
 248
 249         sbi->magic = AUTOFS_SBI_MAGIC;
 250         sbi->flags = AUTOFS_SBI_CATATONIC;
 251         sbi->min_proto = AUTOFS_MIN_PROTO_VERSION;
 252         sbi->max_proto = AUTOFS_MAX_PROTO_VERSION;
 253         sbi->pipefd = -1;
 254
 255         set_autofs_type_indirect(&sbi->type);
 256         mutex_init(&sbi->wq_mutex);
 257         mutex_init(&sbi->pipe_mutex);
 258         spin_lock_init(&sbi->fs_lock);
 259         spin_lock_init(&sbi->lookup_lock);
 260         INIT_LIST_HEAD(&sbi->active_list);
 261         INIT_LIST_HEAD(&sbi->expiring_list);
 262
 263         return sbi;
 264 }
 265
 266 static int autofs_validate_protocol(struct fs_context *fc)
 267 {
 268         struct autofs_sb_info *sbi = fc->s_fs_info;
 269
 270         /* Test versions first */
 271         if (sbi->max_proto < AUTOFS_MIN_PROTO_VERSION ||
 272             sbi->min_proto > AUTOFS_MAX_PROTO_VERSION) {
 273                 errorf(fc, "kernel does not match daemon version "
 274                        "daemon (%d, %d) kernel (%d, %d)\n",
 275                        sbi->min_proto, sbi->max_proto,
 276                        AUTOFS_MIN_PROTO_VERSION, AUTOFS_MAX_PROTO_VERSION);
 277                 return -EINVAL;
 278         }
 279
 280         /* Establish highest kernel protocol version */
 281         if (sbi->max_proto > AUTOFS_MAX_PROTO_VERSION)
 282                 sbi->version = AUTOFS_MAX_PROTO_VERSION;
 283         else
 284                 sbi->version = sbi->max_proto;
 285
 286         switch (sbi->version) {
 287         case 4:
 288                 sbi->sub_version = 7;
 289                 break;
 290         case 5:
 291                 sbi->sub_version = AUTOFS_PROTO_SUBVERSION;
 292                 break;
 293         default:
 294                 sbi->sub_version = 0;
 295         }
 296
 297         return 0;
 298 }
 299
 300 static int autofs_fill_super(struct super_block *s, struct fs_context *fc)
 301 {
 302         struct autofs_fs_context *ctx = fc->fs_private;
 303         struct autofs_sb_info *sbi = s->s_fs_info;
 304         struct inode *root_inode;
 305         struct autofs_info *ino;
 306
 307         pr_debug("starting up, sbi = %p\n", sbi);
 308
 309         sbi->sb = s;
 310         s->s_blocksize = 1024;
 311         s->s_blocksize_bits = 10;
 312         s->s_magic = AUTOFS_SUPER_MAGIC;
 313         s->s_op = &autofs_sops;
 314         s->s_d_op = &autofs_dentry_operations;
 315         s->s_time_gran = 1;
 316
 317         /*
 318          * Get the root inode and dentry, but defer checking for errors.
 319          */
 320         ino = autofs_new_ino(sbi);
 321         if (!ino)
 322                 return -ENOMEM;
 323
 324         root_inode = autofs_get_inode(s, S_IFDIR | 0755);
 325         if (!root_inode)
 326                 return -ENOMEM;
 327
 328         root_inode->i_uid = ctx->uid;
 329         root_inode->i_gid = ctx->gid;
 330         root_inode->i_fop = &autofs_root_operations;
 331         root_inode->i_op = &autofs_dir_inode_operations;
 332
 333         s->s_root = d_make_root(root_inode);
 334         if (unlikely(!s->s_root)) {
 335                 autofs_free_ino(ino);
 336                 return -ENOMEM;
 337         }
 338         s->s_root->d_fsdata = ino;
 339
 340         if (ctx->pgrp_set) {
 341                 sbi->oz_pgrp = find_get_pid(ctx->pgrp);
 342                 if (!sbi->oz_pgrp)
 343                         return invalf(fc, "Could not find process group %d",
 344                                       ctx->pgrp);
 345         } else
 346                 sbi->oz_pgrp = get_task_pid(current, PIDTYPE_PGID);
 347
 348         if (autofs_type_trigger(sbi->type))
 349                 /* s->s_root won't be contended so there's little to
 350                  * be gained by not taking the d_lock when setting
 351                  * d_flags, even when a lot mounts are being done.
 352                  */
 353                 managed_dentry_set_managed(s->s_root);
 354
 355         pr_debug("pipe fd = %d, pgrp = %u\n",
 356                  sbi->pipefd, pid_nr(sbi->oz_pgrp));
 357
 358         sbi->flags &= ~AUTOFS_SBI_CATATONIC;
 359         return 0;
 360 }
 361
 362 /*
 363  * Validate the parameters and then request a superblock.
 364  */
 365 static int autofs_get_tree(struct fs_context *fc)
 366 {
 367         struct autofs_sb_info *sbi = fc->s_fs_info;
 368         int ret;
 369
 370         ret = autofs_validate_protocol(fc);
 371         if (ret)
 372                 return ret;
 373
 374         if (sbi->pipefd < 0)
 375                 return invalf(fc, "No control pipe specified");
 376
 377         return get_tree_nodev(fc, autofs_fill_super);
 378 }
 379
 380 static void autofs_free_fc(struct fs_context *fc)
 381 {
 382         struct autofs_fs_context *ctx = fc->fs_private;
 383         struct autofs_sb_info *sbi = fc->s_fs_info;
 384
 385         if (sbi) {
 386                 if (sbi->pipe)
 387                         fput(sbi->pipe);
 388                 kfree(sbi);
 389         }
 390         kfree(ctx);
 391 }
 392
 393 static const struct fs_context_operations autofs_context_ops = {
 394         .free           = autofs_free_fc,
 395         .parse_param    = autofs_parse_param,
 396         .get_tree       = autofs_get_tree,
 397 };
 398
 399 /*
 400  * Set up the filesystem mount context.
 401  */
 402 int autofs_init_fs_context(struct fs_context *fc)
 403 {
 404         struct autofs_fs_context *ctx;
 405         struct autofs_sb_info *sbi;
 406
 407         ctx = kzalloc(sizeof(struct autofs_fs_context), GFP_KERNEL);
 408         if (!ctx)
 409                 goto nomem;
 410
 411         ctx->uid = current_uid();
 412         ctx->gid = current_gid();
 413
 414         sbi = autofs_alloc_sbi();
 415         if (!sbi)
 416                 goto nomem_ctx;
 417
 418         fc->fs_private = ctx;
 419         fc->s_fs_info = sbi;
 420         fc->ops = &autofs_context_ops;
 421         return 0;
 422
 423 nomem_ctx:
 424         kfree(ctx);
 425 nomem:
 426         return -ENOMEM;
 427 }
 428
 429 struct inode *autofs_get_inode(struct super_block *sb, umode_t mode)
 430 {
 431         struct inode *inode = new_inode(sb);
 432
 433         if (inode == NULL)
 434                 return NULL;
 435
 436         inode->i_mode = mode;
 437         if (sb->s_root) {
 438                 inode->i_uid = d_inode(sb->s_root)->i_uid;
 439                 inode->i_gid = d_inode(sb->s_root)->i_gid;
 440         }
 441         simple_inode_init_ts(inode);
 442         inode->i_ino = get_next_ino();
 443
 444         if (S_ISDIR(mode)) {
 445                 set_nlink(inode, 2);
 446                 inode->i_op = &autofs_dir_inode_operations;
 447                 inode->i_fop = &autofs_dir_operations;
 448         } else if (S_ISLNK(mode)) {
 449                 inode->i_op = &autofs_symlink_inode_operations;
 450         } else
 451                 WARN_ON(1);
 452
 453         return inode;
 454 }