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