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