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/pid_namespace.h> 11 #include <linux/mm.h> 12 #include <linux/string.h> 13 #include <linux/stat.h> 14 #include <linux/completion.h> 15 #include <linux/poll.h> 16 #include <linux/file.h> 17 #include <linux/limits.h> 18 #include <linux/init.h> 19 #include <linux/module.h> 20 #include <linux/sysctl.h> 21 #include <linux/seq_file.h> 22 #include <linux/slab.h> 23 #include <linux/mount.h> 24 25 #include <asm/system.h> 26 #include <asm/uaccess.h> 27 28 #include "internal.h" 29 30 static void proc_evict_inode(struct inode *inode) 31 { 32 struct proc_dir_entry *de; 33 struct ctl_table_header *head; 34 const struct proc_ns_operations *ns_ops; 35 36 truncate_inode_pages(&inode->i_data, 0); 37 end_writeback(inode); 38 39 /* Stop tracking associated processes */ 40 put_pid(PROC_I(inode)->pid); 41 42 /* Let go of any associated proc directory entry */ 43 de = PROC_I(inode)->pde; 44 if (de) 45 pde_put(de); 46 head = PROC_I(inode)->sysctl; 47 if (head) { 48 rcu_assign_pointer(PROC_I(inode)->sysctl, NULL); 49 sysctl_head_put(head); 50 } 51 /* Release any associated namespace */ 52 ns_ops = PROC_I(inode)->ns_ops; 53 if (ns_ops && ns_ops->put) 54 ns_ops->put(PROC_I(inode)->ns); 55 } 56 57 static struct kmem_cache * proc_inode_cachep; 58 59 static struct inode *proc_alloc_inode(struct super_block *sb) 60 { 61 struct proc_inode *ei; 62 struct inode *inode; 63 64 ei = (struct proc_inode *)kmem_cache_alloc(proc_inode_cachep, GFP_KERNEL); 65 if (!ei) 66 return NULL; 67 ei->pid = NULL; 68 ei->fd = 0; 69 ei->op.proc_get_link = NULL; 70 ei->pde = NULL; 71 ei->sysctl = NULL; 72 ei->sysctl_entry = NULL; 73 ei->ns = NULL; 74 ei->ns_ops = NULL; 75 inode = &ei->vfs_inode; 76 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 77 return inode; 78 } 79 80 static void proc_i_callback(struct rcu_head *head) 81 { 82 struct inode *inode = container_of(head, struct inode, i_rcu); 83 kmem_cache_free(proc_inode_cachep, PROC_I(inode)); 84 } 85 86 static void proc_destroy_inode(struct inode *inode) 87 { 88 call_rcu(&inode->i_rcu, proc_i_callback); 89 } 90 91 static void init_once(void *foo) 92 { 93 struct proc_inode *ei = (struct proc_inode *) foo; 94 95 inode_init_once(&ei->vfs_inode); 96 } 97 98 void __init proc_init_inodecache(void) 99 { 100 proc_inode_cachep = kmem_cache_create("proc_inode_cache", 101 sizeof(struct proc_inode), 102 0, (SLAB_RECLAIM_ACCOUNT| 103 SLAB_MEM_SPREAD|SLAB_PANIC), 104 init_once); 105 } 106 107 static int proc_show_options(struct seq_file *seq, struct dentry *root) 108 { 109 struct super_block *sb = root->d_sb; 110 struct pid_namespace *pid = sb->s_fs_info; 111 112 if (pid->pid_gid) 113 seq_printf(seq, ",gid=%lu", (unsigned long)pid->pid_gid); 114 if (pid->hide_pid != 0) 115 seq_printf(seq, ",hidepid=%u", pid->hide_pid); 116 117 return 0; 118 } 119 120 static const struct super_operations proc_sops = { 121 .alloc_inode = proc_alloc_inode, 122 .destroy_inode = proc_destroy_inode, 123 .drop_inode = generic_delete_inode, 124 .evict_inode = proc_evict_inode, 125 .statfs = simple_statfs, 126 .remount_fs = proc_remount, 127 .show_options = proc_show_options, 128 }; 129 130 static void __pde_users_dec(struct proc_dir_entry *pde) 131 { 132 pde->pde_users--; 133 if (pde->pde_unload_completion && pde->pde_users == 0) 134 complete(pde->pde_unload_completion); 135 } 136 137 void pde_users_dec(struct proc_dir_entry *pde) 138 { 139 spin_lock(&pde->pde_unload_lock); 140 __pde_users_dec(pde); 141 spin_unlock(&pde->pde_unload_lock); 142 } 143 144 static loff_t proc_reg_llseek(struct file *file, loff_t offset, int whence) 145 { 146 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode); 147 loff_t rv = -EINVAL; 148 loff_t (*llseek)(struct file *, loff_t, int); 149 150 spin_lock(&pde->pde_unload_lock); 151 /* 152 * remove_proc_entry() is going to delete PDE (as part of module 153 * cleanup sequence). No new callers into module allowed. 154 */ 155 if (!pde->proc_fops) { 156 spin_unlock(&pde->pde_unload_lock); 157 return rv; 158 } 159 /* 160 * Bump refcount so that remove_proc_entry will wail for ->llseek to 161 * complete. 162 */ 163 pde->pde_users++; 164 /* 165 * Save function pointer under lock, to protect against ->proc_fops 166 * NULL'ifying right after ->pde_unload_lock is dropped. 167 */ 168 llseek = pde->proc_fops->llseek; 169 spin_unlock(&pde->pde_unload_lock); 170 171 if (!llseek) 172 llseek = default_llseek; 173 rv = llseek(file, offset, whence); 174 175 pde_users_dec(pde); 176 return rv; 177 } 178 179 static ssize_t proc_reg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) 180 { 181 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode); 182 ssize_t rv = -EIO; 183 ssize_t (*read)(struct file *, char __user *, size_t, loff_t *); 184 185 spin_lock(&pde->pde_unload_lock); 186 if (!pde->proc_fops) { 187 spin_unlock(&pde->pde_unload_lock); 188 return rv; 189 } 190 pde->pde_users++; 191 read = pde->proc_fops->read; 192 spin_unlock(&pde->pde_unload_lock); 193 194 if (read) 195 rv = read(file, buf, count, ppos); 196 197 pde_users_dec(pde); 198 return rv; 199 } 200 201 static ssize_t proc_reg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) 202 { 203 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode); 204 ssize_t rv = -EIO; 205 ssize_t (*write)(struct file *, const char __user *, size_t, loff_t *); 206 207 spin_lock(&pde->pde_unload_lock); 208 if (!pde->proc_fops) { 209 spin_unlock(&pde->pde_unload_lock); 210 return rv; 211 } 212 pde->pde_users++; 213 write = pde->proc_fops->write; 214 spin_unlock(&pde->pde_unload_lock); 215 216 if (write) 217 rv = write(file, buf, count, ppos); 218 219 pde_users_dec(pde); 220 return rv; 221 } 222 223 static unsigned int proc_reg_poll(struct file *file, struct poll_table_struct *pts) 224 { 225 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode); 226 unsigned int rv = DEFAULT_POLLMASK; 227 unsigned int (*poll)(struct file *, struct poll_table_struct *); 228 229 spin_lock(&pde->pde_unload_lock); 230 if (!pde->proc_fops) { 231 spin_unlock(&pde->pde_unload_lock); 232 return rv; 233 } 234 pde->pde_users++; 235 poll = pde->proc_fops->poll; 236 spin_unlock(&pde->pde_unload_lock); 237 238 if (poll) 239 rv = poll(file, pts); 240 241 pde_users_dec(pde); 242 return rv; 243 } 244 245 static long proc_reg_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 246 { 247 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode); 248 long rv = -ENOTTY; 249 long (*ioctl)(struct file *, unsigned int, unsigned long); 250 251 spin_lock(&pde->pde_unload_lock); 252 if (!pde->proc_fops) { 253 spin_unlock(&pde->pde_unload_lock); 254 return rv; 255 } 256 pde->pde_users++; 257 ioctl = pde->proc_fops->unlocked_ioctl; 258 spin_unlock(&pde->pde_unload_lock); 259 260 if (ioctl) 261 rv = ioctl(file, cmd, arg); 262 263 pde_users_dec(pde); 264 return rv; 265 } 266 267 #ifdef CONFIG_COMPAT 268 static long proc_reg_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 269 { 270 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode); 271 long rv = -ENOTTY; 272 long (*compat_ioctl)(struct file *, unsigned int, unsigned long); 273 274 spin_lock(&pde->pde_unload_lock); 275 if (!pde->proc_fops) { 276 spin_unlock(&pde->pde_unload_lock); 277 return rv; 278 } 279 pde->pde_users++; 280 compat_ioctl = pde->proc_fops->compat_ioctl; 281 spin_unlock(&pde->pde_unload_lock); 282 283 if (compat_ioctl) 284 rv = compat_ioctl(file, cmd, arg); 285 286 pde_users_dec(pde); 287 return rv; 288 } 289 #endif 290 291 static int proc_reg_mmap(struct file *file, struct vm_area_struct *vma) 292 { 293 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode); 294 int rv = -EIO; 295 int (*mmap)(struct file *, struct vm_area_struct *); 296 297 spin_lock(&pde->pde_unload_lock); 298 if (!pde->proc_fops) { 299 spin_unlock(&pde->pde_unload_lock); 300 return rv; 301 } 302 pde->pde_users++; 303 mmap = pde->proc_fops->mmap; 304 spin_unlock(&pde->pde_unload_lock); 305 306 if (mmap) 307 rv = mmap(file, vma); 308 309 pde_users_dec(pde); 310 return rv; 311 } 312 313 static int proc_reg_open(struct inode *inode, struct file *file) 314 { 315 struct proc_dir_entry *pde = PDE(inode); 316 int rv = 0; 317 int (*open)(struct inode *, struct file *); 318 int (*release)(struct inode *, struct file *); 319 struct pde_opener *pdeo; 320 321 /* 322 * What for, you ask? Well, we can have open, rmmod, remove_proc_entry 323 * sequence. ->release won't be called because ->proc_fops will be 324 * cleared. Depending on complexity of ->release, consequences vary. 325 * 326 * We can't wait for mercy when close will be done for real, it's 327 * deadlockable: rmmod foo </proc/foo . So, we're going to do ->release 328 * by hand in remove_proc_entry(). For this, save opener's credentials 329 * for later. 330 */ 331 pdeo = kmalloc(sizeof(struct pde_opener), GFP_KERNEL); 332 if (!pdeo) 333 return -ENOMEM; 334 335 spin_lock(&pde->pde_unload_lock); 336 if (!pde->proc_fops) { 337 spin_unlock(&pde->pde_unload_lock); 338 kfree(pdeo); 339 return -ENOENT; 340 } 341 pde->pde_users++; 342 open = pde->proc_fops->open; 343 release = pde->proc_fops->release; 344 spin_unlock(&pde->pde_unload_lock); 345 346 if (open) 347 rv = open(inode, file); 348 349 spin_lock(&pde->pde_unload_lock); 350 if (rv == 0 && release) { 351 /* To know what to release. */ 352 pdeo->inode = inode; 353 pdeo->file = file; 354 /* Strictly for "too late" ->release in proc_reg_release(). */ 355 pdeo->release = release; 356 list_add(&pdeo->lh, &pde->pde_openers); 357 } else 358 kfree(pdeo); 359 __pde_users_dec(pde); 360 spin_unlock(&pde->pde_unload_lock); 361 return rv; 362 } 363 364 static struct pde_opener *find_pde_opener(struct proc_dir_entry *pde, 365 struct inode *inode, struct file *file) 366 { 367 struct pde_opener *pdeo; 368 369 list_for_each_entry(pdeo, &pde->pde_openers, lh) { 370 if (pdeo->inode == inode && pdeo->file == file) 371 return pdeo; 372 } 373 return NULL; 374 } 375 376 static int proc_reg_release(struct inode *inode, struct file *file) 377 { 378 struct proc_dir_entry *pde = PDE(inode); 379 int rv = 0; 380 int (*release)(struct inode *, struct file *); 381 struct pde_opener *pdeo; 382 383 spin_lock(&pde->pde_unload_lock); 384 pdeo = find_pde_opener(pde, inode, file); 385 if (!pde->proc_fops) { 386 /* 387 * Can't simply exit, __fput() will think that everything is OK, 388 * and move on to freeing struct file. remove_proc_entry() will 389 * find slacker in opener's list and will try to do non-trivial 390 * things with struct file. Therefore, remove opener from list. 391 * 392 * But if opener is removed from list, who will ->release it? 393 */ 394 if (pdeo) { 395 list_del(&pdeo->lh); 396 spin_unlock(&pde->pde_unload_lock); 397 rv = pdeo->release(inode, file); 398 kfree(pdeo); 399 } else 400 spin_unlock(&pde->pde_unload_lock); 401 return rv; 402 } 403 pde->pde_users++; 404 release = pde->proc_fops->release; 405 if (pdeo) { 406 list_del(&pdeo->lh); 407 kfree(pdeo); 408 } 409 spin_unlock(&pde->pde_unload_lock); 410 411 if (release) 412 rv = release(inode, file); 413 414 pde_users_dec(pde); 415 return rv; 416 } 417 418 static const struct file_operations proc_reg_file_ops = { 419 .llseek = proc_reg_llseek, 420 .read = proc_reg_read, 421 .write = proc_reg_write, 422 .poll = proc_reg_poll, 423 .unlocked_ioctl = proc_reg_unlocked_ioctl, 424 #ifdef CONFIG_COMPAT 425 .compat_ioctl = proc_reg_compat_ioctl, 426 #endif 427 .mmap = proc_reg_mmap, 428 .open = proc_reg_open, 429 .release = proc_reg_release, 430 }; 431 432 #ifdef CONFIG_COMPAT 433 static const struct file_operations proc_reg_file_ops_no_compat = { 434 .llseek = proc_reg_llseek, 435 .read = proc_reg_read, 436 .write = proc_reg_write, 437 .poll = proc_reg_poll, 438 .unlocked_ioctl = proc_reg_unlocked_ioctl, 439 .mmap = proc_reg_mmap, 440 .open = proc_reg_open, 441 .release = proc_reg_release, 442 }; 443 #endif 444 445 struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de) 446 { 447 struct inode * inode; 448 449 inode = iget_locked(sb, de->low_ino); 450 if (!inode) 451 return NULL; 452 if (inode->i_state & I_NEW) { 453 inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; 454 PROC_I(inode)->fd = 0; 455 PROC_I(inode)->pde = de; 456 457 if (de->mode) { 458 inode->i_mode = de->mode; 459 inode->i_uid = de->uid; 460 inode->i_gid = de->gid; 461 } 462 if (de->size) 463 inode->i_size = de->size; 464 if (de->nlink) 465 set_nlink(inode, de->nlink); 466 if (de->proc_iops) 467 inode->i_op = de->proc_iops; 468 if (de->proc_fops) { 469 if (S_ISREG(inode->i_mode)) { 470 #ifdef CONFIG_COMPAT 471 if (!de->proc_fops->compat_ioctl) 472 inode->i_fop = 473 &proc_reg_file_ops_no_compat; 474 else 475 #endif 476 inode->i_fop = &proc_reg_file_ops; 477 } else { 478 inode->i_fop = de->proc_fops; 479 } 480 } 481 unlock_new_inode(inode); 482 } else 483 pde_put(de); 484 return inode; 485 } 486 487 int proc_fill_super(struct super_block *s) 488 { 489 struct inode * root_inode; 490 491 s->s_flags |= MS_NODIRATIME | MS_NOSUID | MS_NOEXEC; 492 s->s_blocksize = 1024; 493 s->s_blocksize_bits = 10; 494 s->s_magic = PROC_SUPER_MAGIC; 495 s->s_op = &proc_sops; 496 s->s_time_gran = 1; 497 498 pde_get(&proc_root); 499 root_inode = proc_get_inode(s, &proc_root); 500 if (!root_inode) 501 goto out_no_root; 502 root_inode->i_uid = 0; 503 root_inode->i_gid = 0; 504 s->s_root = d_alloc_root(root_inode); 505 if (!s->s_root) 506 goto out_no_root; 507 return 0; 508 509 out_no_root: 510 printk("proc_read_super: get root inode failed\n"); 511 iput(root_inode); 512 pde_put(&proc_root); 513 return -ENOMEM; 514 } 515