fs/proc/inode.c

   1 /*
   2  *  linux/fs/proc/inode.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6
   7 #include <linux/time.h>
   8 #include <linux/proc_fs.h>
   9 #include <linux/kernel.h>
  10 #include <linux/mm.h>
  11 #include <linux/string.h>
  12 #include <linux/stat.h>
  13 #include <linux/completion.h>
  14 #include <linux/poll.h>
  15 #include <linux/file.h>
  16 #include <linux/limits.h>
  17 #include <linux/init.h>
  18 #include <linux/module.h>
  19 #include <linux/smp_lock.h>
  20
  21 #include <asm/system.h>
  22 #include <asm/uaccess.h>
  23
  24 #include "internal.h"
  25
  26 struct proc_dir_entry *de_get(struct proc_dir_entry *de)
  27 {
  28         if (de)
  29                 atomic_inc(&de->count);
  30         return de;
  31 }
  32
  33 /*
  34  * Decrements the use count and checks for deferred deletion.
  35  */
  36 void de_put(struct proc_dir_entry *de)
  37 {
  38         if (de) {
  39                 lock_kernel();
  40                 if (!atomic_read(&de->count)) {
  41                         printk("de_put: entry %s already free!\n", de->name);
  42                         unlock_kernel();
  43                         return;
  44                 }
  45
  46                 if (atomic_dec_and_test(&de->count)) {
  47                         if (de->deleted) {
  48                                 printk("de_put: deferred delete of %s\n",
  49                                         de->name);
  50                                 free_proc_entry(de);
  51                         }
  52                 }
  53                 unlock_kernel();
  54         }
  55 }
  56
  57 /*
  58  * Decrement the use count of the proc_dir_entry.
  59  */
  60 static void proc_delete_inode(struct inode *inode)
  61 {
  62         struct proc_dir_entry *de;
  63
  64         truncate_inode_pages(&inode->i_data, 0);
  65
  66         /* Stop tracking associated processes */
  67         put_pid(PROC_I(inode)->pid);
  68
  69         /* Let go of any associated proc directory entry */
  70         de = PROC_I(inode)->pde;
  71         if (de) {
  72                 if (de->owner)
  73                         module_put(de->owner);
  74                 de_put(de);
  75         }
  76         clear_inode(inode);
  77 }
  78
  79 struct vfsmount *proc_mnt;
  80
  81 static void proc_read_inode(struct inode * inode)
  82 {
  83         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
  84 }
  85
  86 static struct kmem_cache * proc_inode_cachep;
  87
  88 static struct inode *proc_alloc_inode(struct super_block *sb)
  89 {
  90         struct proc_inode *ei;
  91         struct inode *inode;
  92
  93         ei = (struct proc_inode *)kmem_cache_alloc(proc_inode_cachep, GFP_KERNEL);
  94         if (!ei)
  95                 return NULL;
  96         ei->pid = NULL;
  97         ei->fd = 0;
  98         ei->op.proc_get_link = NULL;
  99         ei->pde = NULL;
 100         inode = &ei->vfs_inode;
 101         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
 102         return inode;
 103 }
 104
 105 static void proc_destroy_inode(struct inode *inode)
 106 {
 107         kmem_cache_free(proc_inode_cachep, PROC_I(inode));
 108 }
 109
 110 static void init_once(struct kmem_cache * cachep, void *foo)
 111 {
 112         struct proc_inode *ei = (struct proc_inode *) foo;
 113
 114         inode_init_once(&ei->vfs_inode);
 115 }
 116
 117 int __init proc_init_inodecache(void)
 118 {
 119         proc_inode_cachep = kmem_cache_create("proc_inode_cache",
 120                                              sizeof(struct proc_inode),
 121                                              0, (SLAB_RECLAIM_ACCOUNT|
 122                                                 SLAB_MEM_SPREAD|SLAB_PANIC),
 123                                              init_once);
 124         return 0;
 125 }
 126
 127 static int proc_remount(struct super_block *sb, int *flags, char *data)
 128 {
 129         *flags |= MS_NODIRATIME;
 130         return 0;
 131 }
 132
 133 static const struct super_operations proc_sops = {
 134         .alloc_inode    = proc_alloc_inode,
 135         .destroy_inode  = proc_destroy_inode,
 136         .read_inode     = proc_read_inode,
 137         .drop_inode     = generic_delete_inode,
 138         .delete_inode   = proc_delete_inode,
 139         .statfs         = simple_statfs,
 140         .remount_fs     = proc_remount,
 141 };
 142
 143 static void pde_users_dec(struct proc_dir_entry *pde)
 144 {
 145         spin_lock(&pde->pde_unload_lock);
 146         pde->pde_users--;
 147         if (pde->pde_unload_completion && pde->pde_users == 0)
 148                 complete(pde->pde_unload_completion);
 149         spin_unlock(&pde->pde_unload_lock);
 150 }
 151
 152 static loff_t proc_reg_llseek(struct file *file, loff_t offset, int whence)
 153 {
 154         struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
 155         loff_t rv = -EINVAL;
 156         loff_t (*llseek)(struct file *, loff_t, int);
 157
 158         spin_lock(&pde->pde_unload_lock);
 159         /*
 160          * remove_proc_entry() is going to delete PDE (as part of module
 161          * cleanup sequence). No new callers into module allowed.
 162          */
 163         if (!pde->proc_fops) {
 164                 spin_unlock(&pde->pde_unload_lock);
 165                 return rv;
 166         }
 167         /*
 168          * Bump refcount so that remove_proc_entry will wail for ->llseek to
 169          * complete.
 170          */
 171         pde->pde_users++;
 172         /*
 173          * Save function pointer under lock, to protect against ->proc_fops
 174          * NULL'ifying right after ->pde_unload_lock is dropped.
 175          */
 176         llseek = pde->proc_fops->llseek;
 177         spin_unlock(&pde->pde_unload_lock);
 178
 179         if (!llseek)
 180                 llseek = default_llseek;
 181         rv = llseek(file, offset, whence);
 182
 183         pde_users_dec(pde);
 184         return rv;
 185 }
 186
 187 static ssize_t proc_reg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 188 {
 189         struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
 190         ssize_t rv = -EIO;
 191         ssize_t (*read)(struct file *, char __user *, size_t, loff_t *);
 192
 193         spin_lock(&pde->pde_unload_lock);
 194         if (!pde->proc_fops) {
 195                 spin_unlock(&pde->pde_unload_lock);
 196                 return rv;
 197         }
 198         pde->pde_users++;
 199         read = pde->proc_fops->read;
 200         spin_unlock(&pde->pde_unload_lock);
 201
 202         if (read)
 203                 rv = read(file, buf, count, ppos);
 204
 205         pde_users_dec(pde);
 206         return rv;
 207 }
 208
 209 static ssize_t proc_reg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 210 {
 211         struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
 212         ssize_t rv = -EIO;
 213         ssize_t (*write)(struct file *, const char __user *, size_t, loff_t *);
 214
 215         spin_lock(&pde->pde_unload_lock);
 216         if (!pde->proc_fops) {
 217                 spin_unlock(&pde->pde_unload_lock);
 218                 return rv;
 219         }
 220         pde->pde_users++;
 221         write = pde->proc_fops->write;
 222         spin_unlock(&pde->pde_unload_lock);
 223
 224         if (write)
 225                 rv = write(file, buf, count, ppos);
 226
 227         pde_users_dec(pde);
 228         return rv;
 229 }
 230
 231 static unsigned int proc_reg_poll(struct file *file, struct poll_table_struct *pts)
 232 {
 233         struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
 234         unsigned int rv = DEFAULT_POLLMASK;
 235         unsigned int (*poll)(struct file *, struct poll_table_struct *);
 236
 237         spin_lock(&pde->pde_unload_lock);
 238         if (!pde->proc_fops) {
 239                 spin_unlock(&pde->pde_unload_lock);
 240                 return rv;
 241         }
 242         pde->pde_users++;
 243         poll = pde->proc_fops->poll;
 244         spin_unlock(&pde->pde_unload_lock);
 245
 246         if (poll)
 247                 rv = poll(file, pts);
 248
 249         pde_users_dec(pde);
 250         return rv;
 251 }
 252
 253 static long proc_reg_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 254 {
 255         struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
 256         long rv = -ENOTTY;
 257         long (*unlocked_ioctl)(struct file *, unsigned int, unsigned long);
 258         int (*ioctl)(struct inode *, struct file *, unsigned int, unsigned long);
 259
 260         spin_lock(&pde->pde_unload_lock);
 261         if (!pde->proc_fops) {
 262                 spin_unlock(&pde->pde_unload_lock);
 263                 return rv;
 264         }
 265         pde->pde_users++;
 266         unlocked_ioctl = pde->proc_fops->unlocked_ioctl;
 267         ioctl = pde->proc_fops->ioctl;
 268         spin_unlock(&pde->pde_unload_lock);
 269
 270         if (unlocked_ioctl) {
 271                 rv = unlocked_ioctl(file, cmd, arg);
 272                 if (rv == -ENOIOCTLCMD)
 273                         rv = -EINVAL;
 274         } else if (ioctl) {
 275                 lock_kernel();
 276                 rv = ioctl(file->f_path.dentry->d_inode, file, cmd, arg);
 277                 unlock_kernel();
 278         }
 279
 280         pde_users_dec(pde);
 281         return rv;
 282 }
 283
 284 #ifdef CONFIG_COMPAT
 285 static long proc_reg_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 286 {
 287         struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
 288         long rv = -ENOTTY;
 289         long (*compat_ioctl)(struct file *, unsigned int, unsigned long);
 290
 291         spin_lock(&pde->pde_unload_lock);
 292         if (!pde->proc_fops) {
 293                 spin_unlock(&pde->pde_unload_lock);
 294                 return rv;
 295         }
 296         pde->pde_users++;
 297         compat_ioctl = pde->proc_fops->compat_ioctl;
 298         spin_unlock(&pde->pde_unload_lock);
 299
 300         if (compat_ioctl)
 301                 rv = compat_ioctl(file, cmd, arg);
 302
 303         pde_users_dec(pde);
 304         return rv;
 305 }
 306 #endif
 307
 308 static int proc_reg_mmap(struct file *file, struct vm_area_struct *vma)
 309 {
 310         struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
 311         int rv = -EIO;
 312         int (*mmap)(struct file *, struct vm_area_struct *);
 313
 314         spin_lock(&pde->pde_unload_lock);
 315         if (!pde->proc_fops) {
 316                 spin_unlock(&pde->pde_unload_lock);
 317                 return rv;
 318         }
 319         pde->pde_users++;
 320         mmap = pde->proc_fops->mmap;
 321         spin_unlock(&pde->pde_unload_lock);
 322
 323         if (mmap)
 324                 rv = mmap(file, vma);
 325
 326         pde_users_dec(pde);
 327         return rv;
 328 }
 329
 330 static int proc_reg_open(struct inode *inode, struct file *file)
 331 {
 332         struct proc_dir_entry *pde = PDE(inode);
 333         int rv = 0;
 334         int (*open)(struct inode *, struct file *);
 335
 336         spin_lock(&pde->pde_unload_lock);
 337         if (!pde->proc_fops) {
 338                 spin_unlock(&pde->pde_unload_lock);
 339                 return rv;
 340         }
 341         pde->pde_users++;
 342         open = pde->proc_fops->open;
 343         spin_unlock(&pde->pde_unload_lock);
 344
 345         if (open)
 346                 rv = open(inode, file);
 347
 348         pde_users_dec(pde);
 349         return rv;
 350 }
 351
 352 static int proc_reg_release(struct inode *inode, struct file *file)
 353 {
 354         struct proc_dir_entry *pde = PDE(inode);
 355         int rv = 0;
 356         int (*release)(struct inode *, struct file *);
 357
 358         spin_lock(&pde->pde_unload_lock);
 359         if (!pde->proc_fops) {
 360                 spin_unlock(&pde->pde_unload_lock);
 361                 return rv;
 362         }
 363         pde->pde_users++;
 364         release = pde->proc_fops->release;
 365         spin_unlock(&pde->pde_unload_lock);
 366
 367         if (release)
 368                 rv = release(inode, file);
 369
 370         pde_users_dec(pde);
 371         return rv;
 372 }
 373
 374 static const struct file_operations proc_reg_file_ops = {
 375         .llseek         = proc_reg_llseek,
 376         .read           = proc_reg_read,
 377         .write          = proc_reg_write,
 378         .poll           = proc_reg_poll,
 379         .unlocked_ioctl = proc_reg_unlocked_ioctl,
 380 #ifdef CONFIG_COMPAT
 381         .compat_ioctl   = proc_reg_compat_ioctl,
 382 #endif
 383         .mmap           = proc_reg_mmap,
 384         .open           = proc_reg_open,
 385         .release        = proc_reg_release,
 386 };
 387
 388 #ifdef CONFIG_COMPAT
 389 static const struct file_operations proc_reg_file_ops_no_compat = {
 390         .llseek         = proc_reg_llseek,
 391         .read           = proc_reg_read,
 392         .write          = proc_reg_write,
 393         .poll           = proc_reg_poll,
 394         .unlocked_ioctl = proc_reg_unlocked_ioctl,
 395         .mmap           = proc_reg_mmap,
 396         .open           = proc_reg_open,
 397         .release        = proc_reg_release,
 398 };
 399 #endif
 400
 401 struct inode *proc_get_inode(struct super_block *sb, unsigned int ino,
 402                                 struct proc_dir_entry *de)
 403 {
 404         struct inode * inode;
 405
 406         if (de != NULL && !try_module_get(de->owner))
 407                 goto out_mod;
 408
 409         inode = iget(sb, ino);
 410         if (!inode)
 411                 goto out_ino;
 412
 413         PROC_I(inode)->fd = 0;
 414         PROC_I(inode)->pde = de;
 415         if (de) {
 416                 if (de->mode) {
 417                         inode->i_mode = de->mode;
 418                         inode->i_uid = de->uid;
 419                         inode->i_gid = de->gid;
 420                 }
 421                 if (de->size)
 422                         inode->i_size = de->size;
 423                 if (de->nlink)
 424                         inode->i_nlink = de->nlink;
 425                 if (de->proc_iops)
 426                         inode->i_op = de->proc_iops;
 427                 if (de->proc_fops) {
 428                         if (S_ISREG(inode->i_mode)) {
 429 #ifdef CONFIG_COMPAT
 430                                 if (!de->proc_fops->compat_ioctl)
 431                                         inode->i_fop =
 432                                                 &proc_reg_file_ops_no_compat;
 433                                 else
 434 #endif
 435                                         inode->i_fop = &proc_reg_file_ops;
 436                         }
 437                         else
 438                                 inode->i_fop = de->proc_fops;
 439                 }
 440         }
 441
 442         return inode;
 443
 444 out_ino:
 445         if (de != NULL)
 446                 module_put(de->owner);
 447 out_mod:
 448         return NULL;
 449 }
 450
 451 int proc_fill_super(struct super_block *s)
 452 {
 453         struct inode * root_inode;
 454
 455         s->s_flags |= MS_NODIRATIME | MS_NOSUID | MS_NOEXEC;
 456         s->s_blocksize = 1024;
 457         s->s_blocksize_bits = 10;
 458         s->s_magic = PROC_SUPER_MAGIC;
 459         s->s_op = &proc_sops;
 460         s->s_time_gran = 1;
 461
 462         de_get(&proc_root);
 463         root_inode = proc_get_inode(s, PROC_ROOT_INO, &proc_root);
 464         if (!root_inode)
 465                 goto out_no_root;
 466         root_inode->i_uid = 0;
 467         root_inode->i_gid = 0;
 468         s->s_root = d_alloc_root(root_inode);
 469         if (!s->s_root)
 470                 goto out_no_root;
 471         return 0;
 472
 473 out_no_root:
 474         printk("proc_read_super: get root inode failed\n");
 475         iput(root_inode);
 476         de_put(&proc_root);
 477         return -ENOMEM;
 478 }
 479 MODULE_LICENSE("GPL");