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/sysctl.h> 20 #include <linux/slab.h> 21 22 #include <asm/system.h> 23 #include <asm/uaccess.h> 24 25 #include "internal.h" 26 27 static void proc_evict_inode(struct inode *inode) 28 { 29 struct proc_dir_entry *de; 30 struct ctl_table_header *head; 31 const struct proc_ns_operations *ns_ops; 32 33 truncate_inode_pages(&inode->i_data, 0); 34 end_writeback(inode); 35 36 /* Stop tracking associated processes */ 37 put_pid(PROC_I(inode)->pid); 38 39 /* Let go of any associated proc directory entry */ 40 de = PROC_I(inode)->pde; 41 if (de) 42 pde_put(de); 43 head = PROC_I(inode)->sysctl; 44 if (head) { 45 rcu_assign_pointer(PROC_I(inode)->sysctl, NULL); 46 sysctl_head_put(head); 47 } 48 /* Release any associated namespace */ 49 ns_ops = PROC_I(inode)->ns_ops; 50 if (ns_ops && ns_ops->put) 51 ns_ops->put(PROC_I(inode)->ns); 52 } 53 54 static struct kmem_cache * proc_inode_cachep; 55 56 static struct inode *proc_alloc_inode(struct super_block *sb) 57 { 58 struct proc_inode *ei; 59 struct inode *inode; 60 61 ei = (struct proc_inode *)kmem_cache_alloc(proc_inode_cachep, GFP_KERNEL); 62 if (!ei) 63 return NULL; 64 ei->pid = NULL; 65 ei->fd = 0; 66 ei->op.proc_get_link = NULL; 67 ei->pde = NULL; 68 ei->sysctl = NULL; 69 ei->sysctl_entry = NULL; 70 ei->ns = NULL; 71 ei->ns_ops = NULL; 72 inode = &ei->vfs_inode; 73 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 74 return inode; 75 } 76 77 static void proc_i_callback(struct rcu_head *head) 78 { 79 struct inode *inode = container_of(head, struct inode, i_rcu); 80 kmem_cache_free(proc_inode_cachep, PROC_I(inode)); 81 } 82 83 static void proc_destroy_inode(struct inode *inode) 84 { 85 call_rcu(&inode->i_rcu, proc_i_callback); 86 } 87 88 static void init_once(void *foo) 89 { 90 struct proc_inode *ei = (struct proc_inode *) foo; 91 92 inode_init_once(&ei->vfs_inode); 93 } 94 95 void __init proc_init_inodecache(void) 96 { 97 proc_inode_cachep = kmem_cache_create("proc_inode_cache", 98 sizeof(struct proc_inode), 99 0, (SLAB_RECLAIM_ACCOUNT| 100 SLAB_MEM_SPREAD|SLAB_PANIC), 101 init_once); 102 } 103 104 static const struct super_operations proc_sops = { 105 .alloc_inode = proc_alloc_inode, 106 .destroy_inode = proc_destroy_inode, 107 .drop_inode = generic_delete_inode, 108 .evict_inode = proc_evict_inode, 109 .statfs = simple_statfs, 110 }; 111 112 static void __pde_users_dec(struct proc_dir_entry *pde) 113 { 114 pde->pde_users--; 115 if (pde->pde_unload_completion && pde->pde_users == 0) 116 complete(pde->pde_unload_completion); 117 } 118 119 void pde_users_dec(struct proc_dir_entry *pde) 120 { 121 spin_lock(&pde->pde_unload_lock); 122 __pde_users_dec(pde); 123 spin_unlock(&pde->pde_unload_lock); 124 } 125 126 static loff_t proc_reg_llseek(struct file *file, loff_t offset, int whence) 127 { 128 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode); 129 loff_t rv = -EINVAL; 130 loff_t (*llseek)(struct file *, loff_t, int); 131 132 spin_lock(&pde->pde_unload_lock); 133 /* 134 * remove_proc_entry() is going to delete PDE (as part of module 135 * cleanup sequence). No new callers into module allowed. 136 */ 137 if (!pde->proc_fops) { 138 spin_unlock(&pde->pde_unload_lock); 139 return rv; 140 } 141 /* 142 * Bump refcount so that remove_proc_entry will wail for ->llseek to 143 * complete. 144 */ 145 pde->pde_users++; 146 /* 147 * Save function pointer under lock, to protect against ->proc_fops 148 * NULL'ifying right after ->pde_unload_lock is dropped. 149 */ 150 llseek = pde->proc_fops->llseek; 151 spin_unlock(&pde->pde_unload_lock); 152 153 if (!llseek) 154 llseek = default_llseek; 155 rv = llseek(file, offset, whence); 156 157 pde_users_dec(pde); 158 return rv; 159 } 160 161 static ssize_t proc_reg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) 162 { 163 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode); 164 ssize_t rv = -EIO; 165 ssize_t (*read)(struct file *, char __user *, size_t, loff_t *); 166 167 spin_lock(&pde->pde_unload_lock); 168 if (!pde->proc_fops) { 169 spin_unlock(&pde->pde_unload_lock); 170 return rv; 171 } 172 pde->pde_users++; 173 read = pde->proc_fops->read; 174 spin_unlock(&pde->pde_unload_lock); 175 176 if (read) 177 rv = read(file, buf, count, ppos); 178 179 pde_users_dec(pde); 180 return rv; 181 } 182 183 static ssize_t proc_reg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) 184 { 185 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode); 186 ssize_t rv = -EIO; 187 ssize_t (*write)(struct file *, const char __user *, size_t, loff_t *); 188 189 spin_lock(&pde->pde_unload_lock); 190 if (!pde->proc_fops) { 191 spin_unlock(&pde->pde_unload_lock); 192 return rv; 193 } 194 pde->pde_users++; 195 write = pde->proc_fops->write; 196 spin_unlock(&pde->pde_unload_lock); 197 198 if (write) 199 rv = write(file, buf, count, ppos); 200 201 pde_users_dec(pde); 202 return rv; 203 } 204 205 static unsigned int proc_reg_poll(struct file *file, struct poll_table_struct *pts) 206 { 207 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode); 208 unsigned int rv = DEFAULT_POLLMASK; 209 unsigned int (*poll)(struct file *, struct poll_table_struct *); 210 211 spin_lock(&pde->pde_unload_lock); 212 if (!pde->proc_fops) { 213 spin_unlock(&pde->pde_unload_lock); 214 return rv; 215 } 216 pde->pde_users++; 217 poll = pde->proc_fops->poll; 218 spin_unlock(&pde->pde_unload_lock); 219 220 if (poll) 221 rv = poll(file, pts); 222 223 pde_users_dec(pde); 224 return rv; 225 } 226 227 static long proc_reg_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 228 { 229 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode); 230 long rv = -ENOTTY; 231 long (*ioctl)(struct file *, unsigned int, unsigned long); 232 233 spin_lock(&pde->pde_unload_lock); 234 if (!pde->proc_fops) { 235 spin_unlock(&pde->pde_unload_lock); 236 return rv; 237 } 238 pde->pde_users++; 239 ioctl = pde->proc_fops->unlocked_ioctl; 240 spin_unlock(&pde->pde_unload_lock); 241 242 if (ioctl) 243 rv = ioctl(file, cmd, arg); 244 245 pde_users_dec(pde); 246 return rv; 247 } 248 249 #ifdef CONFIG_COMPAT 250 static long proc_reg_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 251 { 252 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode); 253 long rv = -ENOTTY; 254 long (*compat_ioctl)(struct file *, unsigned int, unsigned long); 255 256 spin_lock(&pde->pde_unload_lock); 257 if (!pde->proc_fops) { 258 spin_unlock(&pde->pde_unload_lock); 259 return rv; 260 } 261 pde->pde_users++; 262 compat_ioctl = pde->proc_fops->compat_ioctl; 263 spin_unlock(&pde->pde_unload_lock); 264 265 if (compat_ioctl) 266 rv = compat_ioctl(file, cmd, arg); 267 268 pde_users_dec(pde); 269 return rv; 270 } 271 #endif 272 273 static int proc_reg_mmap(struct file *file, struct vm_area_struct *vma) 274 { 275 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode); 276 int rv = -EIO; 277 int (*mmap)(struct file *, struct vm_area_struct *); 278 279 spin_lock(&pde->pde_unload_lock); 280 if (!pde->proc_fops) { 281 spin_unlock(&pde->pde_unload_lock); 282 return rv; 283 } 284 pde->pde_users++; 285 mmap = pde->proc_fops->mmap; 286 spin_unlock(&pde->pde_unload_lock); 287 288 if (mmap) 289 rv = mmap(file, vma); 290 291 pde_users_dec(pde); 292 return rv; 293 } 294 295 static int proc_reg_open(struct inode *inode, struct file *file) 296 { 297 struct proc_dir_entry *pde = PDE(inode); 298 int rv = 0; 299 int (*open)(struct inode *, struct file *); 300 int (*release)(struct inode *, struct file *); 301 struct pde_opener *pdeo; 302 303 /* 304 * What for, you ask? Well, we can have open, rmmod, remove_proc_entry 305 * sequence. ->release won't be called because ->proc_fops will be 306 * cleared. Depending on complexity of ->release, consequences vary. 307 * 308 * We can't wait for mercy when close will be done for real, it's 309 * deadlockable: rmmod foo </proc/foo . So, we're going to do ->release 310 * by hand in remove_proc_entry(). For this, save opener's credentials 311 * for later. 312 */ 313 pdeo = kmalloc(sizeof(struct pde_opener), GFP_KERNEL); 314 if (!pdeo) 315 return -ENOMEM; 316 317 spin_lock(&pde->pde_unload_lock); 318 if (!pde->proc_fops) { 319 spin_unlock(&pde->pde_unload_lock); 320 kfree(pdeo); 321 return -ENOENT; 322 } 323 pde->pde_users++; 324 open = pde->proc_fops->open; 325 release = pde->proc_fops->release; 326 spin_unlock(&pde->pde_unload_lock); 327 328 if (open) 329 rv = open(inode, file); 330 331 spin_lock(&pde->pde_unload_lock); 332 if (rv == 0 && release) { 333 /* To know what to release. */ 334 pdeo->inode = inode; 335 pdeo->file = file; 336 /* Strictly for "too late" ->release in proc_reg_release(). */ 337 pdeo->release = release; 338 list_add(&pdeo->lh, &pde->pde_openers); 339 } else 340 kfree(pdeo); 341 __pde_users_dec(pde); 342 spin_unlock(&pde->pde_unload_lock); 343 return rv; 344 } 345 346 static struct pde_opener *find_pde_opener(struct proc_dir_entry *pde, 347 struct inode *inode, struct file *file) 348 { 349 struct pde_opener *pdeo; 350 351 list_for_each_entry(pdeo, &pde->pde_openers, lh) { 352 if (pdeo->inode == inode && pdeo->file == file) 353 return pdeo; 354 } 355 return NULL; 356 } 357 358 static int proc_reg_release(struct inode *inode, struct file *file) 359 { 360 struct proc_dir_entry *pde = PDE(inode); 361 int rv = 0; 362 int (*release)(struct inode *, struct file *); 363 struct pde_opener *pdeo; 364 365 spin_lock(&pde->pde_unload_lock); 366 pdeo = find_pde_opener(pde, inode, file); 367 if (!pde->proc_fops) { 368 /* 369 * Can't simply exit, __fput() will think that everything is OK, 370 * and move on to freeing struct file. remove_proc_entry() will 371 * find slacker in opener's list and will try to do non-trivial 372 * things with struct file. Therefore, remove opener from list. 373 * 374 * But if opener is removed from list, who will ->release it? 375 */ 376 if (pdeo) { 377 list_del(&pdeo->lh); 378 spin_unlock(&pde->pde_unload_lock); 379 rv = pdeo->release(inode, file); 380 kfree(pdeo); 381 } else 382 spin_unlock(&pde->pde_unload_lock); 383 return rv; 384 } 385 pde->pde_users++; 386 release = pde->proc_fops->release; 387 if (pdeo) { 388 list_del(&pdeo->lh); 389 kfree(pdeo); 390 } 391 spin_unlock(&pde->pde_unload_lock); 392 393 if (release) 394 rv = release(inode, file); 395 396 pde_users_dec(pde); 397 return rv; 398 } 399 400 static const struct file_operations proc_reg_file_ops = { 401 .llseek = proc_reg_llseek, 402 .read = proc_reg_read, 403 .write = proc_reg_write, 404 .poll = proc_reg_poll, 405 .unlocked_ioctl = proc_reg_unlocked_ioctl, 406 #ifdef CONFIG_COMPAT 407 .compat_ioctl = proc_reg_compat_ioctl, 408 #endif 409 .mmap = proc_reg_mmap, 410 .open = proc_reg_open, 411 .release = proc_reg_release, 412 }; 413 414 #ifdef CONFIG_COMPAT 415 static const struct file_operations proc_reg_file_ops_no_compat = { 416 .llseek = proc_reg_llseek, 417 .read = proc_reg_read, 418 .write = proc_reg_write, 419 .poll = proc_reg_poll, 420 .unlocked_ioctl = proc_reg_unlocked_ioctl, 421 .mmap = proc_reg_mmap, 422 .open = proc_reg_open, 423 .release = proc_reg_release, 424 }; 425 #endif 426 427 struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de) 428 { 429 struct inode * inode; 430 431 inode = iget_locked(sb, de->low_ino); 432 if (!inode) 433 return NULL; 434 if (inode->i_state & I_NEW) { 435 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 436 PROC_I(inode)->fd = 0; 437 PROC_I(inode)->pde = de; 438 439 if (de->mode) { 440 inode->i_mode = de->mode; 441 inode->i_uid = de->uid; 442 inode->i_gid = de->gid; 443 } 444 if (de->size) 445 inode->i_size = de->size; 446 if (de->nlink) 447 set_nlink(inode, de->nlink); 448 if (de->proc_iops) 449 inode->i_op = de->proc_iops; 450 if (de->proc_fops) { 451 if (S_ISREG(inode->i_mode)) { 452 #ifdef CONFIG_COMPAT 453 if (!de->proc_fops->compat_ioctl) 454 inode->i_fop = 455 &proc_reg_file_ops_no_compat; 456 else 457 #endif 458 inode->i_fop = &proc_reg_file_ops; 459 } else { 460 inode->i_fop = de->proc_fops; 461 } 462 } 463 unlock_new_inode(inode); 464 } else 465 pde_put(de); 466 return inode; 467 } 468 469 int proc_fill_super(struct super_block *s) 470 { 471 struct inode * root_inode; 472 473 s->s_flags |= MS_NODIRATIME | MS_NOSUID | MS_NOEXEC; 474 s->s_blocksize = 1024; 475 s->s_blocksize_bits = 10; 476 s->s_magic = PROC_SUPER_MAGIC; 477 s->s_op = &proc_sops; 478 s->s_time_gran = 1; 479 480 pde_get(&proc_root); 481 root_inode = proc_get_inode(s, &proc_root); 482 if (!root_inode) 483 goto out_no_root; 484 root_inode->i_uid = 0; 485 root_inode->i_gid = 0; 486 s->s_root = d_alloc_root(root_inode); 487 if (!s->s_root) 488 goto out_no_root; 489 return 0; 490 491 out_no_root: 492 printk("proc_read_super: get root inode failed\n"); 493 iput(root_inode); 494 pde_put(&proc_root); 495 return -ENOMEM; 496 } 497