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