fs/proc/inode.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  linux/fs/proc/inode.c
   4  *
   5  *  Copyright (C) 1991, 1992  Linus Torvalds
   6  */
   7
   8 #include <linux/cache.h>
   9 #include <linux/time.h>
  10 #include <linux/proc_fs.h>
  11 #include <linux/kernel.h>
  12 #include <linux/pid_namespace.h>
  13 #include <linux/mm.h>
  14 #include <linux/string.h>
  15 #include <linux/stat.h>
  16 #include <linux/completion.h>
  17 #include <linux/poll.h>
  18 #include <linux/printk.h>
  19 #include <linux/file.h>
  20 #include <linux/limits.h>
  21 #include <linux/init.h>
  22 #include <linux/module.h>
  23 #include <linux/sysctl.h>
  24 #include <linux/seq_file.h>
  25 #include <linux/slab.h>
  26 #include <linux/mount.h>
  27 #include <linux/bug.h>
  28
  29 #include "internal.h"
  30
  31 static void proc_evict_inode(struct inode *inode)
  32 {
  33         struct proc_dir_entry *de;
  34         struct ctl_table_header *head;
  35         struct proc_inode *ei = PROC_I(inode);
  36
  37         truncate_inode_pages_final(&inode->i_data);
  38         clear_inode(inode);
  39
  40         /* Stop tracking associated processes */
  41         if (ei->pid) {
  42                 proc_pid_evict_inode(ei);
  43                 ei->pid = NULL;
  44         }
  45
  46         /* Let go of any associated proc directory entry */
  47         de = ei->pde;
  48         if (de) {
  49                 pde_put(de);
  50                 ei->pde = NULL;
  51         }
  52
  53         head = ei->sysctl;
  54         if (head) {
  55                 RCU_INIT_POINTER(ei->sysctl, NULL);
  56                 proc_sys_evict_inode(inode, head);
  57         }
  58 }
  59
  60 static struct kmem_cache *proc_inode_cachep __ro_after_init;
  61 static struct kmem_cache *pde_opener_cache __ro_after_init;
  62
  63 static struct inode *proc_alloc_inode(struct super_block *sb)
  64 {
  65         struct proc_inode *ei;
  66
  67         ei = alloc_inode_sb(sb, proc_inode_cachep, GFP_KERNEL);
  68         if (!ei)
  69                 return NULL;
  70         ei->pid = NULL;
  71         ei->fd = 0;
  72         ei->op.proc_get_link = NULL;
  73         ei->pde = NULL;
  74         ei->sysctl = NULL;
  75         ei->sysctl_entry = NULL;
  76         INIT_HLIST_NODE(&ei->sibling_inodes);
  77         ei->ns_ops = NULL;
  78         return &ei->vfs_inode;
  79 }
  80
  81 static void proc_free_inode(struct inode *inode)
  82 {
  83         kmem_cache_free(proc_inode_cachep, PROC_I(inode));
  84 }
  85
  86 static void init_once(void *foo)
  87 {
  88         struct proc_inode *ei = (struct proc_inode *) foo;
  89
  90         inode_init_once(&ei->vfs_inode);
  91 }
  92
  93 void __init proc_init_kmemcache(void)
  94 {
  95         proc_inode_cachep = kmem_cache_create("proc_inode_cache",
  96                                              sizeof(struct proc_inode),
  97                                              0, (SLAB_RECLAIM_ACCOUNT|
  98                                                 SLAB_MEM_SPREAD|SLAB_ACCOUNT|
  99                                                 SLAB_PANIC),
 100                                              init_once);
 101         pde_opener_cache =
 102                 kmem_cache_create("pde_opener", sizeof(struct pde_opener), 0,
 103                                   SLAB_ACCOUNT|SLAB_PANIC, NULL);
 104         proc_dir_entry_cache = kmem_cache_create_usercopy(
 105                 "proc_dir_entry", SIZEOF_PDE, 0, SLAB_PANIC,
 106                 offsetof(struct proc_dir_entry, inline_name),
 107                 SIZEOF_PDE_INLINE_NAME, NULL);
 108         BUILD_BUG_ON(sizeof(struct proc_dir_entry) >= SIZEOF_PDE);
 109 }
 110
 111 void proc_invalidate_siblings_dcache(struct hlist_head *inodes, spinlock_t *lock)
 112 {
 113         struct inode *inode;
 114         struct proc_inode *ei;
 115         struct hlist_node *node;
 116         struct super_block *old_sb = NULL;
 117
 118         rcu_read_lock();
 119         for (;;) {
 120                 struct super_block *sb;
 121                 node = hlist_first_rcu(inodes);
 122                 if (!node)
 123                         break;
 124                 ei = hlist_entry(node, struct proc_inode, sibling_inodes);
 125                 spin_lock(lock);
 126                 hlist_del_init_rcu(&ei->sibling_inodes);
 127                 spin_unlock(lock);
 128
 129                 inode = &ei->vfs_inode;
 130                 sb = inode->i_sb;
 131                 if ((sb != old_sb) && !atomic_inc_not_zero(&sb->s_active))
 132                         continue;
 133                 inode = igrab(inode);
 134                 rcu_read_unlock();
 135                 if (sb != old_sb) {
 136                         if (old_sb)
 137                                 deactivate_super(old_sb);
 138                         old_sb = sb;
 139                 }
 140                 if (unlikely(!inode)) {
 141                         rcu_read_lock();
 142                         continue;
 143                 }
 144
 145                 if (S_ISDIR(inode->i_mode)) {
 146                         struct dentry *dir = d_find_any_alias(inode);
 147                         if (dir) {
 148                                 d_invalidate(dir);
 149                                 dput(dir);
 150                         }
 151                 } else {
 152                         struct dentry *dentry;
 153                         while ((dentry = d_find_alias(inode))) {
 154                                 d_invalidate(dentry);
 155                                 dput(dentry);
 156                         }
 157                 }
 158                 iput(inode);
 159
 160                 rcu_read_lock();
 161         }
 162         rcu_read_unlock();
 163         if (old_sb)
 164                 deactivate_super(old_sb);
 165 }
 166
 167 static inline const char *hidepid2str(enum proc_hidepid v)
 168 {
 169         switch (v) {
 170                 case HIDEPID_OFF: return "off";
 171                 case HIDEPID_NO_ACCESS: return "noaccess";
 172                 case HIDEPID_INVISIBLE: return "invisible";
 173                 case HIDEPID_NOT_PTRACEABLE: return "ptraceable";
 174         }
 175         WARN_ONCE(1, "bad hide_pid value: %d\n", v);
 176         return "unknown";
 177 }
 178
 179 static int proc_show_options(struct seq_file *seq, struct dentry *root)
 180 {
 181         struct proc_fs_info *fs_info = proc_sb_info(root->d_sb);
 182
 183         if (!gid_eq(fs_info->pid_gid, GLOBAL_ROOT_GID))
 184                 seq_printf(seq, ",gid=%u", from_kgid_munged(&init_user_ns, fs_info->pid_gid));
 185         if (fs_info->hide_pid != HIDEPID_OFF)
 186                 seq_printf(seq, ",hidepid=%s", hidepid2str(fs_info->hide_pid));
 187         if (fs_info->pidonly != PROC_PIDONLY_OFF)
 188                 seq_printf(seq, ",subset=pid");
 189
 190         return 0;
 191 }
 192
 193 const struct super_operations proc_sops = {
 194         .alloc_inode    = proc_alloc_inode,
 195         .free_inode     = proc_free_inode,
 196         .drop_inode     = generic_delete_inode,
 197         .evict_inode    = proc_evict_inode,
 198         .statfs         = simple_statfs,
 199         .show_options   = proc_show_options,
 200 };
 201
 202 enum {BIAS = -1U<<31};
 203
 204 static inline int use_pde(struct proc_dir_entry *pde)
 205 {
 206         return likely(atomic_inc_unless_negative(&pde->in_use));
 207 }
 208
 209 static void unuse_pde(struct proc_dir_entry *pde)
 210 {
 211         if (unlikely(atomic_dec_return(&pde->in_use) == BIAS))
 212                 complete(pde->pde_unload_completion);
 213 }
 214
 215 /*
 216  * At most 2 contexts can enter this function: the one doing the last
 217  * close on the descriptor and whoever is deleting PDE itself.
 218  *
 219  * First to enter calls ->proc_release hook and signals its completion
 220  * to the second one which waits and then does nothing.
 221  *
 222  * PDE is locked on entry, unlocked on exit.
 223  */
 224 static void close_pdeo(struct proc_dir_entry *pde, struct pde_opener *pdeo)
 225         __releases(&pde->pde_unload_lock)
 226 {
 227         /*
 228          * close() (proc_reg_release()) can't delete an entry and proceed:
 229          * ->release hook needs to be available at the right moment.
 230          *
 231          * rmmod (remove_proc_entry() et al) can't delete an entry and proceed:
 232          * "struct file" needs to be available at the right moment.
 233          */
 234         if (pdeo->closing) {
 235                 /* somebody else is doing that, just wait */
 236                 DECLARE_COMPLETION_ONSTACK(c);
 237                 pdeo->c = &c;
 238                 spin_unlock(&pde->pde_unload_lock);
 239                 wait_for_completion(&c);
 240         } else {
 241                 struct file *file;
 242                 struct completion *c;
 243
 244                 pdeo->closing = true;
 245                 spin_unlock(&pde->pde_unload_lock);
 246
 247                 file = pdeo->file;
 248                 pde->proc_ops->proc_release(file_inode(file), file);
 249
 250                 spin_lock(&pde->pde_unload_lock);
 251                 /* Strictly after ->proc_release, see above. */
 252                 list_del(&pdeo->lh);
 253                 c = pdeo->c;
 254                 spin_unlock(&pde->pde_unload_lock);
 255                 if (unlikely(c))
 256                         complete(c);
 257                 kmem_cache_free(pde_opener_cache, pdeo);
 258         }
 259 }
 260
 261 void proc_entry_rundown(struct proc_dir_entry *de)
 262 {
 263         DECLARE_COMPLETION_ONSTACK(c);
 264         /* Wait until all existing callers into module are done. */
 265         de->pde_unload_completion = &c;
 266         if (atomic_add_return(BIAS, &de->in_use) != BIAS)
 267                 wait_for_completion(&c);
 268
 269         /* ->pde_openers list can't grow from now on. */
 270
 271         spin_lock(&de->pde_unload_lock);
 272         while (!list_empty(&de->pde_openers)) {
 273                 struct pde_opener *pdeo;
 274                 pdeo = list_first_entry(&de->pde_openers, struct pde_opener, lh);
 275                 close_pdeo(de, pdeo);
 276                 spin_lock(&de->pde_unload_lock);
 277         }
 278         spin_unlock(&de->pde_unload_lock);
 279 }
 280
 281 static loff_t proc_reg_llseek(struct file *file, loff_t offset, int whence)
 282 {
 283         struct proc_dir_entry *pde = PDE(file_inode(file));
 284         loff_t rv = -EINVAL;
 285
 286         if (pde_is_permanent(pde)) {
 287                 return pde->proc_ops->proc_lseek(file, offset, whence);
 288         } else if (use_pde(pde)) {
 289                 rv = pde->proc_ops->proc_lseek(file, offset, whence);
 290                 unuse_pde(pde);
 291         }
 292         return rv;
 293 }
 294
 295 static ssize_t proc_reg_read_iter(struct kiocb *iocb, struct iov_iter *iter)
 296 {
 297         struct proc_dir_entry *pde = PDE(file_inode(iocb->ki_filp));
 298         ssize_t ret;
 299
 300         if (pde_is_permanent(pde))
 301                 return pde->proc_ops->proc_read_iter(iocb, iter);
 302
 303         if (!use_pde(pde))
 304                 return -EIO;
 305         ret = pde->proc_ops->proc_read_iter(iocb, iter);
 306         unuse_pde(pde);
 307         return ret;
 308 }
 309
 310 static ssize_t pde_read(struct proc_dir_entry *pde, struct file *file, char __user *buf, size_t count, loff_t *ppos)
 311 {
 312         typeof_member(struct proc_ops, proc_read) read;
 313
 314         read = pde->proc_ops->proc_read;
 315         if (read)
 316                 return read(file, buf, count, ppos);
 317         return -EIO;
 318 }
 319
 320 static ssize_t proc_reg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 321 {
 322         struct proc_dir_entry *pde = PDE(file_inode(file));
 323         ssize_t rv = -EIO;
 324
 325         if (pde_is_permanent(pde)) {
 326                 return pde_read(pde, file, buf, count, ppos);
 327         } else if (use_pde(pde)) {
 328                 rv = pde_read(pde, file, buf, count, ppos);
 329                 unuse_pde(pde);
 330         }
 331         return rv;
 332 }
 333
 334 static ssize_t pde_write(struct proc_dir_entry *pde, struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 335 {
 336         typeof_member(struct proc_ops, proc_write) write;
 337
 338         write = pde->proc_ops->proc_write;
 339         if (write)
 340                 return write(file, buf, count, ppos);
 341         return -EIO;
 342 }
 343
 344 static ssize_t proc_reg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 345 {
 346         struct proc_dir_entry *pde = PDE(file_inode(file));
 347         ssize_t rv = -EIO;
 348
 349         if (pde_is_permanent(pde)) {
 350                 return pde_write(pde, file, buf, count, ppos);
 351         } else if (use_pde(pde)) {
 352                 rv = pde_write(pde, file, buf, count, ppos);
 353                 unuse_pde(pde);
 354         }
 355         return rv;
 356 }
 357
 358 static __poll_t pde_poll(struct proc_dir_entry *pde, struct file *file, struct poll_table_struct *pts)
 359 {
 360         typeof_member(struct proc_ops, proc_poll) poll;
 361
 362         poll = pde->proc_ops->proc_poll;
 363         if (poll)
 364                 return poll(file, pts);
 365         return DEFAULT_POLLMASK;
 366 }
 367
 368 static __poll_t proc_reg_poll(struct file *file, struct poll_table_struct *pts)
 369 {
 370         struct proc_dir_entry *pde = PDE(file_inode(file));
 371         __poll_t rv = DEFAULT_POLLMASK;
 372
 373         if (pde_is_permanent(pde)) {
 374                 return pde_poll(pde, file, pts);
 375         } else if (use_pde(pde)) {
 376                 rv = pde_poll(pde, file, pts);
 377                 unuse_pde(pde);
 378         }
 379         return rv;
 380 }
 381
 382 static long pde_ioctl(struct proc_dir_entry *pde, struct file *file, unsigned int cmd, unsigned long arg)
 383 {
 384         typeof_member(struct proc_ops, proc_ioctl) ioctl;
 385
 386         ioctl = pde->proc_ops->proc_ioctl;
 387         if (ioctl)
 388                 return ioctl(file, cmd, arg);
 389         return -ENOTTY;
 390 }
 391
 392 static long proc_reg_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 393 {
 394         struct proc_dir_entry *pde = PDE(file_inode(file));
 395         long rv = -ENOTTY;
 396
 397         if (pde_is_permanent(pde)) {
 398                 return pde_ioctl(pde, file, cmd, arg);
 399         } else if (use_pde(pde)) {
 400                 rv = pde_ioctl(pde, file, cmd, arg);
 401                 unuse_pde(pde);
 402         }
 403         return rv;
 404 }
 405
 406 #ifdef CONFIG_COMPAT
 407 static long pde_compat_ioctl(struct proc_dir_entry *pde, struct file *file, unsigned int cmd, unsigned long arg)
 408 {
 409         typeof_member(struct proc_ops, proc_compat_ioctl) compat_ioctl;
 410
 411         compat_ioctl = pde->proc_ops->proc_compat_ioctl;
 412         if (compat_ioctl)
 413                 return compat_ioctl(file, cmd, arg);
 414         return -ENOTTY;
 415 }
 416
 417 static long proc_reg_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 418 {
 419         struct proc_dir_entry *pde = PDE(file_inode(file));
 420         long rv = -ENOTTY;
 421         if (pde_is_permanent(pde)) {
 422                 return pde_compat_ioctl(pde, file, cmd, arg);
 423         } else if (use_pde(pde)) {
 424                 rv = pde_compat_ioctl(pde, file, cmd, arg);
 425                 unuse_pde(pde);
 426         }
 427         return rv;
 428 }
 429 #endif
 430
 431 static int pde_mmap(struct proc_dir_entry *pde, struct file *file, struct vm_area_struct *vma)
 432 {
 433         typeof_member(struct proc_ops, proc_mmap) mmap;
 434
 435         mmap = pde->proc_ops->proc_mmap;
 436         if (mmap)
 437                 return mmap(file, vma);
 438         return -EIO;
 439 }
 440
 441 static int proc_reg_mmap(struct file *file, struct vm_area_struct *vma)
 442 {
 443         struct proc_dir_entry *pde = PDE(file_inode(file));
 444         int rv = -EIO;
 445
 446         if (pde_is_permanent(pde)) {
 447                 return pde_mmap(pde, file, vma);
 448         } else if (use_pde(pde)) {
 449                 rv = pde_mmap(pde, file, vma);
 450                 unuse_pde(pde);
 451         }
 452         return rv;
 453 }
 454
 455 static unsigned long
 456 pde_get_unmapped_area(struct proc_dir_entry *pde, struct file *file, unsigned long orig_addr,
 457                            unsigned long len, unsigned long pgoff,
 458                            unsigned long flags)
 459 {
 460         typeof_member(struct proc_ops, proc_get_unmapped_area) get_area;
 461
 462         get_area = pde->proc_ops->proc_get_unmapped_area;
 463 #ifdef CONFIG_MMU
 464         if (!get_area)
 465                 get_area = current->mm->get_unmapped_area;
 466 #endif
 467         if (get_area)
 468                 return get_area(file, orig_addr, len, pgoff, flags);
 469         return orig_addr;
 470 }
 471
 472 static unsigned long
 473 proc_reg_get_unmapped_area(struct file *file, unsigned long orig_addr,
 474                            unsigned long len, unsigned long pgoff,
 475                            unsigned long flags)
 476 {
 477         struct proc_dir_entry *pde = PDE(file_inode(file));
 478         unsigned long rv = -EIO;
 479
 480         if (pde_is_permanent(pde)) {
 481                 return pde_get_unmapped_area(pde, file, orig_addr, len, pgoff, flags);
 482         } else if (use_pde(pde)) {
 483                 rv = pde_get_unmapped_area(pde, file, orig_addr, len, pgoff, flags);
 484                 unuse_pde(pde);
 485         }
 486         return rv;
 487 }
 488
 489 static int proc_reg_open(struct inode *inode, struct file *file)
 490 {
 491         struct proc_dir_entry *pde = PDE(inode);
 492         int rv = 0;
 493         typeof_member(struct proc_ops, proc_open) open;
 494         typeof_member(struct proc_ops, proc_release) release;
 495         struct pde_opener *pdeo;
 496
 497         if (!pde->proc_ops->proc_lseek)
 498                 file->f_mode &= ~FMODE_LSEEK;
 499
 500         if (pde_is_permanent(pde)) {
 501                 open = pde->proc_ops->proc_open;
 502                 if (open)
 503                         rv = open(inode, file);
 504                 return rv;
 505         }
 506
 507         /*
 508          * Ensure that
 509          * 1) PDE's ->release hook will be called no matter what
 510          *    either normally by close()/->release, or forcefully by
 511          *    rmmod/remove_proc_entry.
 512          *
 513          * 2) rmmod isn't blocked by opening file in /proc and sitting on
 514          *    the descriptor (including "rmmod foo </proc/foo" scenario).
 515          *
 516          * Save every "struct file" with custom ->release hook.
 517          */
 518         if (!use_pde(pde))
 519                 return -ENOENT;
 520
 521         release = pde->proc_ops->proc_release;
 522         if (release) {
 523                 pdeo = kmem_cache_alloc(pde_opener_cache, GFP_KERNEL);
 524                 if (!pdeo) {
 525                         rv = -ENOMEM;
 526                         goto out_unuse;
 527                 }
 528         }
 529
 530         open = pde->proc_ops->proc_open;
 531         if (open)
 532                 rv = open(inode, file);
 533
 534         if (release) {
 535                 if (rv == 0) {
 536                         /* To know what to release. */
 537                         pdeo->file = file;
 538                         pdeo->closing = false;
 539                         pdeo->c = NULL;
 540                         spin_lock(&pde->pde_unload_lock);
 541                         list_add(&pdeo->lh, &pde->pde_openers);
 542                         spin_unlock(&pde->pde_unload_lock);
 543                 } else
 544                         kmem_cache_free(pde_opener_cache, pdeo);
 545         }
 546
 547 out_unuse:
 548         unuse_pde(pde);
 549         return rv;
 550 }
 551
 552 static int proc_reg_release(struct inode *inode, struct file *file)
 553 {
 554         struct proc_dir_entry *pde = PDE(inode);
 555         struct pde_opener *pdeo;
 556
 557         if (pde_is_permanent(pde)) {
 558                 typeof_member(struct proc_ops, proc_release) release;
 559
 560                 release = pde->proc_ops->proc_release;
 561                 if (release) {
 562                         return release(inode, file);
 563                 }
 564                 return 0;
 565         }
 566
 567         spin_lock(&pde->pde_unload_lock);
 568         list_for_each_entry(pdeo, &pde->pde_openers, lh) {
 569                 if (pdeo->file == file) {
 570                         close_pdeo(pde, pdeo);
 571                         return 0;
 572                 }
 573         }
 574         spin_unlock(&pde->pde_unload_lock);
 575         return 0;
 576 }
 577
 578 static const struct file_operations proc_reg_file_ops = {
 579         .llseek         = proc_reg_llseek,
 580         .read           = proc_reg_read,
 581         .write          = proc_reg_write,
 582         .poll           = proc_reg_poll,
 583         .unlocked_ioctl = proc_reg_unlocked_ioctl,
 584         .mmap           = proc_reg_mmap,
 585         .get_unmapped_area = proc_reg_get_unmapped_area,
 586         .open           = proc_reg_open,
 587         .release        = proc_reg_release,
 588 };
 589
 590 static const struct file_operations proc_iter_file_ops = {
 591         .llseek         = proc_reg_llseek,
 592         .read_iter      = proc_reg_read_iter,
 593         .write          = proc_reg_write,
 594         .splice_read    = generic_file_splice_read,
 595         .poll           = proc_reg_poll,
 596         .unlocked_ioctl = proc_reg_unlocked_ioctl,
 597         .mmap           = proc_reg_mmap,
 598         .get_unmapped_area = proc_reg_get_unmapped_area,
 599         .open           = proc_reg_open,
 600         .release        = proc_reg_release,
 601 };
 602
 603 #ifdef CONFIG_COMPAT
 604 static const struct file_operations proc_reg_file_ops_compat = {
 605         .llseek         = proc_reg_llseek,
 606         .read           = proc_reg_read,
 607         .write          = proc_reg_write,
 608         .poll           = proc_reg_poll,
 609         .unlocked_ioctl = proc_reg_unlocked_ioctl,
 610         .compat_ioctl   = proc_reg_compat_ioctl,
 611         .mmap           = proc_reg_mmap,
 612         .get_unmapped_area = proc_reg_get_unmapped_area,
 613         .open           = proc_reg_open,
 614         .release        = proc_reg_release,
 615 };
 616
 617 static const struct file_operations proc_iter_file_ops_compat = {
 618         .llseek         = proc_reg_llseek,
 619         .read_iter      = proc_reg_read_iter,
 620         .splice_read    = generic_file_splice_read,
 621         .write          = proc_reg_write,
 622         .poll           = proc_reg_poll,
 623         .unlocked_ioctl = proc_reg_unlocked_ioctl,
 624         .compat_ioctl   = proc_reg_compat_ioctl,
 625         .mmap           = proc_reg_mmap,
 626         .get_unmapped_area = proc_reg_get_unmapped_area,
 627         .open           = proc_reg_open,
 628         .release        = proc_reg_release,
 629 };
 630 #endif
 631
 632 static void proc_put_link(void *p)
 633 {
 634         unuse_pde(p);
 635 }
 636
 637 static const char *proc_get_link(struct dentry *dentry,
 638                                  struct inode *inode,
 639                                  struct delayed_call *done)
 640 {
 641         struct proc_dir_entry *pde = PDE(inode);
 642         if (!use_pde(pde))
 643                 return ERR_PTR(-EINVAL);
 644         set_delayed_call(done, proc_put_link, pde);
 645         return pde->data;
 646 }
 647
 648 const struct inode_operations proc_link_inode_operations = {
 649         .get_link       = proc_get_link,
 650 };
 651
 652 struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de)
 653 {
 654         struct inode *inode = new_inode(sb);
 655
 656         if (!inode) {
 657                 pde_put(de);
 658                 return NULL;
 659         }
 660
 661         inode->i_private = de->data;
 662         inode->i_ino = de->low_ino;
 663         inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
 664         PROC_I(inode)->pde = de;
 665         if (is_empty_pde(de)) {
 666                 make_empty_dir_inode(inode);
 667                 return inode;
 668         }
 669
 670         if (de->mode) {
 671                 inode->i_mode = de->mode;
 672                 inode->i_uid = de->uid;
 673                 inode->i_gid = de->gid;
 674         }
 675         if (de->size)
 676                 inode->i_size = de->size;
 677         if (de->nlink)
 678                 set_nlink(inode, de->nlink);
 679
 680         if (S_ISREG(inode->i_mode)) {
 681                 inode->i_op = de->proc_iops;
 682                 if (de->proc_ops->proc_read_iter)
 683                         inode->i_fop = &proc_iter_file_ops;
 684                 else
 685                         inode->i_fop = &proc_reg_file_ops;
 686 #ifdef CONFIG_COMPAT
 687                 if (de->proc_ops->proc_compat_ioctl) {
 688                         if (de->proc_ops->proc_read_iter)
 689                                 inode->i_fop = &proc_iter_file_ops_compat;
 690                         else
 691                                 inode->i_fop = &proc_reg_file_ops_compat;
 692                 }
 693 #endif
 694         } else if (S_ISDIR(inode->i_mode)) {
 695                 inode->i_op = de->proc_iops;
 696                 inode->i_fop = de->proc_dir_ops;
 697         } else if (S_ISLNK(inode->i_mode)) {
 698                 inode->i_op = de->proc_iops;
 699                 inode->i_fop = NULL;
 700         } else {
 701                 BUG();
 702         }
 703         return inode;
 704 }