| 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/printk.h> |
| 17 | #include <linux/file.h> |
| 18 | #include <linux/limits.h> |
| 19 | #include <linux/init.h> |
| 20 | #include <linux/module.h> |
| 21 | #include <linux/sysctl.h> |
| 22 | #include <linux/seq_file.h> |
| 23 | #include <linux/slab.h> |
| 24 | #include <linux/mount.h> |
| 25 | #include <linux/magic.h> |
| 26 | |
| 27 | #include <asm/uaccess.h> |
| 28 | |
| 29 | #include "internal.h" |
| 30 | |
| 31 | static void proc_evict_inode(struct inode *inode) |
| 32 | { |
| 33 | struct proc_dir_entry *de; |
| 34 | struct ctl_table_header *head; |
| 35 | const struct proc_ns_operations *ns_ops; |
| 36 | void *ns; |
| 37 | |
| 38 | truncate_inode_pages(&inode->i_data, 0); |
| 39 | clear_inode(inode); |
| 40 | |
| 41 | /* Stop tracking associated processes */ |
| 42 | put_pid(PROC_I(inode)->pid); |
| 43 | |
| 44 | /* Let go of any associated proc directory entry */ |
| 45 | de = PROC_I(inode)->pde; |
| 46 | if (de) |
| 47 | pde_put(de); |
| 48 | head = PROC_I(inode)->sysctl; |
| 49 | if (head) { |
| 50 | rcu_assign_pointer(PROC_I(inode)->sysctl, NULL); |
| 51 | sysctl_head_put(head); |
| 52 | } |
| 53 | /* Release any associated namespace */ |
| 54 | ns_ops = PROC_I(inode)->ns.ns_ops; |
| 55 | ns = PROC_I(inode)->ns.ns; |
| 56 | if (ns_ops && ns) |
| 57 | ns_ops->put(ns); |
| 58 | } |
| 59 | |
| 60 | static struct kmem_cache * proc_inode_cachep; |
| 61 | |
| 62 | static struct inode *proc_alloc_inode(struct super_block *sb) |
| 63 | { |
| 64 | struct proc_inode *ei; |
| 65 | struct inode *inode; |
| 66 | |
| 67 | ei = (struct proc_inode *)kmem_cache_alloc(proc_inode_cachep, GFP_KERNEL); |
| 68 | if (!ei) |
| 69 | return NULL; |
| 70 | ei->pid = NULL; |
| 71 | ei->fd = 0; |
| 72 | ei->op.proc_get_link = NULL; |
| 73 | ei->pde = NULL; |
| 74 | ei->sysctl = NULL; |
| 75 | ei->sysctl_entry = NULL; |
| 76 | ei->ns.ns = NULL; |
| 77 | ei->ns.ns_ops = NULL; |
| 78 | inode = &ei->vfs_inode; |
| 79 | inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; |
| 80 | return inode; |
| 81 | } |
| 82 | |
| 83 | static void proc_i_callback(struct rcu_head *head) |
| 84 | { |
| 85 | struct inode *inode = container_of(head, struct inode, i_rcu); |
| 86 | kmem_cache_free(proc_inode_cachep, PROC_I(inode)); |
| 87 | } |
| 88 | |
| 89 | static void proc_destroy_inode(struct inode *inode) |
| 90 | { |
| 91 | call_rcu(&inode->i_rcu, proc_i_callback); |
| 92 | } |
| 93 | |
| 94 | static void init_once(void *foo) |
| 95 | { |
| 96 | struct proc_inode *ei = (struct proc_inode *) foo; |
| 97 | |
| 98 | inode_init_once(&ei->vfs_inode); |
| 99 | } |
| 100 | |
| 101 | void __init proc_init_inodecache(void) |
| 102 | { |
| 103 | proc_inode_cachep = kmem_cache_create("proc_inode_cache", |
| 104 | sizeof(struct proc_inode), |
| 105 | 0, (SLAB_RECLAIM_ACCOUNT| |
| 106 | SLAB_MEM_SPREAD|SLAB_PANIC), |
| 107 | init_once); |
| 108 | } |
| 109 | |
| 110 | static int proc_show_options(struct seq_file *seq, struct dentry *root) |
| 111 | { |
| 112 | struct super_block *sb = root->d_sb; |
| 113 | struct pid_namespace *pid = sb->s_fs_info; |
| 114 | |
| 115 | if (!gid_eq(pid->pid_gid, GLOBAL_ROOT_GID)) |
| 116 | seq_printf(seq, ",gid=%u", from_kgid_munged(&init_user_ns, pid->pid_gid)); |
| 117 | if (pid->hide_pid != 0) |
| 118 | seq_printf(seq, ",hidepid=%u", pid->hide_pid); |
| 119 | |
| 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 | .evict_inode = proc_evict_inode, |
| 128 | .statfs = simple_statfs, |
| 129 | .remount_fs = proc_remount, |
| 130 | .show_options = proc_show_options, |
| 131 | }; |
| 132 | |
| 133 | enum {BIAS = -1U<<31}; |
| 134 | |
| 135 | static inline int use_pde(struct proc_dir_entry *pde) |
| 136 | { |
| 137 | return atomic_inc_unless_negative(&pde->in_use); |
| 138 | } |
| 139 | |
| 140 | static void unuse_pde(struct proc_dir_entry *pde) |
| 141 | { |
| 142 | if (atomic_dec_return(&pde->in_use) == BIAS) |
| 143 | complete(pde->pde_unload_completion); |
| 144 | } |
| 145 | |
| 146 | /* pde is locked */ |
| 147 | static void close_pdeo(struct proc_dir_entry *pde, struct pde_opener *pdeo) |
| 148 | { |
| 149 | if (pdeo->closing) { |
| 150 | /* somebody else is doing that, just wait */ |
| 151 | DECLARE_COMPLETION_ONSTACK(c); |
| 152 | pdeo->c = &c; |
| 153 | spin_unlock(&pde->pde_unload_lock); |
| 154 | wait_for_completion(&c); |
| 155 | spin_lock(&pde->pde_unload_lock); |
| 156 | } else { |
| 157 | struct file *file; |
| 158 | pdeo->closing = 1; |
| 159 | spin_unlock(&pde->pde_unload_lock); |
| 160 | file = pdeo->file; |
| 161 | pde->proc_fops->release(file_inode(file), file); |
| 162 | spin_lock(&pde->pde_unload_lock); |
| 163 | list_del_init(&pdeo->lh); |
| 164 | if (pdeo->c) |
| 165 | complete(pdeo->c); |
| 166 | kfree(pdeo); |
| 167 | } |
| 168 | } |
| 169 | |
| 170 | void proc_entry_rundown(struct proc_dir_entry *de) |
| 171 | { |
| 172 | DECLARE_COMPLETION_ONSTACK(c); |
| 173 | /* Wait until all existing callers into module are done. */ |
| 174 | de->pde_unload_completion = &c; |
| 175 | if (atomic_add_return(BIAS, &de->in_use) != BIAS) |
| 176 | wait_for_completion(&c); |
| 177 | |
| 178 | spin_lock(&de->pde_unload_lock); |
| 179 | while (!list_empty(&de->pde_openers)) { |
| 180 | struct pde_opener *pdeo; |
| 181 | pdeo = list_first_entry(&de->pde_openers, struct pde_opener, lh); |
| 182 | close_pdeo(de, pdeo); |
| 183 | } |
| 184 | spin_unlock(&de->pde_unload_lock); |
| 185 | } |
| 186 | |
| 187 | static loff_t proc_reg_llseek(struct file *file, loff_t offset, int whence) |
| 188 | { |
| 189 | struct proc_dir_entry *pde = PDE(file_inode(file)); |
| 190 | loff_t rv = -EINVAL; |
| 191 | if (use_pde(pde)) { |
| 192 | loff_t (*llseek)(struct file *, loff_t, int); |
| 193 | llseek = pde->proc_fops->llseek; |
| 194 | if (!llseek) |
| 195 | llseek = default_llseek; |
| 196 | rv = llseek(file, offset, whence); |
| 197 | unuse_pde(pde); |
| 198 | } |
| 199 | return rv; |
| 200 | } |
| 201 | |
| 202 | static ssize_t proc_reg_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) |
| 203 | { |
| 204 | ssize_t (*read)(struct file *, char __user *, size_t, loff_t *); |
| 205 | struct proc_dir_entry *pde = PDE(file_inode(file)); |
| 206 | ssize_t rv = -EIO; |
| 207 | if (use_pde(pde)) { |
| 208 | read = pde->proc_fops->read; |
| 209 | if (read) |
| 210 | rv = read(file, buf, count, ppos); |
| 211 | unuse_pde(pde); |
| 212 | } |
| 213 | return rv; |
| 214 | } |
| 215 | |
| 216 | static ssize_t proc_reg_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) |
| 217 | { |
| 218 | ssize_t (*write)(struct file *, const char __user *, size_t, loff_t *); |
| 219 | struct proc_dir_entry *pde = PDE(file_inode(file)); |
| 220 | ssize_t rv = -EIO; |
| 221 | if (use_pde(pde)) { |
| 222 | write = pde->proc_fops->write; |
| 223 | if (write) |
| 224 | rv = write(file, buf, count, ppos); |
| 225 | unuse_pde(pde); |
| 226 | } |
| 227 | return rv; |
| 228 | } |
| 229 | |
| 230 | static unsigned int proc_reg_poll(struct file *file, struct poll_table_struct *pts) |
| 231 | { |
| 232 | struct proc_dir_entry *pde = PDE(file_inode(file)); |
| 233 | unsigned int rv = DEFAULT_POLLMASK; |
| 234 | unsigned int (*poll)(struct file *, struct poll_table_struct *); |
| 235 | if (use_pde(pde)) { |
| 236 | poll = pde->proc_fops->poll; |
| 237 | if (poll) |
| 238 | rv = poll(file, pts); |
| 239 | unuse_pde(pde); |
| 240 | } |
| 241 | return rv; |
| 242 | } |
| 243 | |
| 244 | static long proc_reg_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg) |
| 245 | { |
| 246 | struct proc_dir_entry *pde = PDE(file_inode(file)); |
| 247 | long rv = -ENOTTY; |
| 248 | long (*ioctl)(struct file *, unsigned int, unsigned long); |
| 249 | if (use_pde(pde)) { |
| 250 | ioctl = pde->proc_fops->unlocked_ioctl; |
| 251 | if (ioctl) |
| 252 | rv = ioctl(file, cmd, arg); |
| 253 | unuse_pde(pde); |
| 254 | } |
| 255 | return rv; |
| 256 | } |
| 257 | |
| 258 | #ifdef CONFIG_COMPAT |
| 259 | static long proc_reg_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) |
| 260 | { |
| 261 | struct proc_dir_entry *pde = PDE(file_inode(file)); |
| 262 | long rv = -ENOTTY; |
| 263 | long (*compat_ioctl)(struct file *, unsigned int, unsigned long); |
| 264 | if (use_pde(pde)) { |
| 265 | compat_ioctl = pde->proc_fops->compat_ioctl; |
| 266 | if (compat_ioctl) |
| 267 | rv = compat_ioctl(file, cmd, arg); |
| 268 | unuse_pde(pde); |
| 269 | } |
| 270 | return rv; |
| 271 | } |
| 272 | #endif |
| 273 | |
| 274 | static int proc_reg_mmap(struct file *file, struct vm_area_struct *vma) |
| 275 | { |
| 276 | struct proc_dir_entry *pde = PDE(file_inode(file)); |
| 277 | int rv = -EIO; |
| 278 | int (*mmap)(struct file *, struct vm_area_struct *); |
| 279 | if (use_pde(pde)) { |
| 280 | mmap = pde->proc_fops->mmap; |
| 281 | if (mmap) |
| 282 | rv = mmap(file, vma); |
| 283 | unuse_pde(pde); |
| 284 | } |
| 285 | return rv; |
| 286 | } |
| 287 | |
| 288 | static unsigned long proc_reg_get_unmapped_area(struct file *file, unsigned long orig_addr, unsigned long len, unsigned long pgoff, unsigned long flags) |
| 289 | { |
| 290 | struct proc_dir_entry *pde = PDE(file_inode(file)); |
| 291 | unsigned long rv = -EIO; |
| 292 | unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long) = NULL; |
| 293 | if (use_pde(pde)) { |
| 294 | #ifdef CONFIG_MMU |
| 295 | get_unmapped_area = current->mm->get_unmapped_area; |
| 296 | #endif |
| 297 | if (pde->proc_fops->get_unmapped_area) |
| 298 | get_unmapped_area = pde->proc_fops->get_unmapped_area; |
| 299 | if (get_unmapped_area) |
| 300 | rv = get_unmapped_area(file, orig_addr, len, pgoff, flags); |
| 301 | unuse_pde(pde); |
| 302 | } |
| 303 | return rv; |
| 304 | } |
| 305 | |
| 306 | static int proc_reg_open(struct inode *inode, struct file *file) |
| 307 | { |
| 308 | struct proc_dir_entry *pde = PDE(inode); |
| 309 | int rv = 0; |
| 310 | int (*open)(struct inode *, struct file *); |
| 311 | int (*release)(struct inode *, struct file *); |
| 312 | struct pde_opener *pdeo; |
| 313 | |
| 314 | /* |
| 315 | * What for, you ask? Well, we can have open, rmmod, remove_proc_entry |
| 316 | * sequence. ->release won't be called because ->proc_fops will be |
| 317 | * cleared. Depending on complexity of ->release, consequences vary. |
| 318 | * |
| 319 | * We can't wait for mercy when close will be done for real, it's |
| 320 | * deadlockable: rmmod foo </proc/foo . So, we're going to do ->release |
| 321 | * by hand in remove_proc_entry(). For this, save opener's credentials |
| 322 | * for later. |
| 323 | */ |
| 324 | pdeo = kzalloc(sizeof(struct pde_opener), GFP_KERNEL); |
| 325 | if (!pdeo) |
| 326 | return -ENOMEM; |
| 327 | |
| 328 | if (!use_pde(pde)) { |
| 329 | kfree(pdeo); |
| 330 | return -ENOENT; |
| 331 | } |
| 332 | open = pde->proc_fops->open; |
| 333 | release = pde->proc_fops->release; |
| 334 | |
| 335 | if (open) |
| 336 | rv = open(inode, file); |
| 337 | |
| 338 | if (rv == 0 && release) { |
| 339 | /* To know what to release. */ |
| 340 | pdeo->file = file; |
| 341 | /* Strictly for "too late" ->release in proc_reg_release(). */ |
| 342 | spin_lock(&pde->pde_unload_lock); |
| 343 | list_add(&pdeo->lh, &pde->pde_openers); |
| 344 | spin_unlock(&pde->pde_unload_lock); |
| 345 | } else |
| 346 | kfree(pdeo); |
| 347 | |
| 348 | unuse_pde(pde); |
| 349 | return rv; |
| 350 | } |
| 351 | |
| 352 | static int proc_reg_release(struct inode *inode, struct file *file) |
| 353 | { |
| 354 | struct proc_dir_entry *pde = PDE(inode); |
| 355 | struct pde_opener *pdeo; |
| 356 | spin_lock(&pde->pde_unload_lock); |
| 357 | list_for_each_entry(pdeo, &pde->pde_openers, lh) { |
| 358 | if (pdeo->file == file) { |
| 359 | close_pdeo(pde, pdeo); |
| 360 | break; |
| 361 | } |
| 362 | } |
| 363 | spin_unlock(&pde->pde_unload_lock); |
| 364 | return 0; |
| 365 | } |
| 366 | |
| 367 | static const struct file_operations proc_reg_file_ops = { |
| 368 | .llseek = proc_reg_llseek, |
| 369 | .read = proc_reg_read, |
| 370 | .write = proc_reg_write, |
| 371 | .poll = proc_reg_poll, |
| 372 | .unlocked_ioctl = proc_reg_unlocked_ioctl, |
| 373 | #ifdef CONFIG_COMPAT |
| 374 | .compat_ioctl = proc_reg_compat_ioctl, |
| 375 | #endif |
| 376 | .mmap = proc_reg_mmap, |
| 377 | .get_unmapped_area = proc_reg_get_unmapped_area, |
| 378 | .open = proc_reg_open, |
| 379 | .release = proc_reg_release, |
| 380 | }; |
| 381 | |
| 382 | #ifdef CONFIG_COMPAT |
| 383 | static const struct file_operations proc_reg_file_ops_no_compat = { |
| 384 | .llseek = proc_reg_llseek, |
| 385 | .read = proc_reg_read, |
| 386 | .write = proc_reg_write, |
| 387 | .poll = proc_reg_poll, |
| 388 | .unlocked_ioctl = proc_reg_unlocked_ioctl, |
| 389 | .mmap = proc_reg_mmap, |
| 390 | .get_unmapped_area = proc_reg_get_unmapped_area, |
| 391 | .open = proc_reg_open, |
| 392 | .release = proc_reg_release, |
| 393 | }; |
| 394 | #endif |
| 395 | |
| 396 | struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de) |
| 397 | { |
| 398 | struct inode *inode = new_inode_pseudo(sb); |
| 399 | |
| 400 | if (inode) { |
| 401 | inode->i_ino = de->low_ino; |
| 402 | inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME; |
| 403 | PROC_I(inode)->pde = de; |
| 404 | |
| 405 | if (de->mode) { |
| 406 | inode->i_mode = de->mode; |
| 407 | inode->i_uid = de->uid; |
| 408 | inode->i_gid = de->gid; |
| 409 | } |
| 410 | if (de->size) |
| 411 | inode->i_size = de->size; |
| 412 | if (de->nlink) |
| 413 | set_nlink(inode, de->nlink); |
| 414 | WARN_ON(!de->proc_iops); |
| 415 | inode->i_op = de->proc_iops; |
| 416 | if (de->proc_fops) { |
| 417 | if (S_ISREG(inode->i_mode)) { |
| 418 | #ifdef CONFIG_COMPAT |
| 419 | if (!de->proc_fops->compat_ioctl) |
| 420 | inode->i_fop = |
| 421 | &proc_reg_file_ops_no_compat; |
| 422 | else |
| 423 | #endif |
| 424 | inode->i_fop = &proc_reg_file_ops; |
| 425 | } else { |
| 426 | inode->i_fop = de->proc_fops; |
| 427 | } |
| 428 | } |
| 429 | } else |
| 430 | pde_put(de); |
| 431 | return inode; |
| 432 | } |
| 433 | |
| 434 | int proc_fill_super(struct super_block *s) |
| 435 | { |
| 436 | struct inode *root_inode; |
| 437 | |
| 438 | s->s_flags |= MS_NODIRATIME | MS_NOSUID | MS_NOEXEC; |
| 439 | s->s_blocksize = 1024; |
| 440 | s->s_blocksize_bits = 10; |
| 441 | s->s_magic = PROC_SUPER_MAGIC; |
| 442 | s->s_op = &proc_sops; |
| 443 | s->s_time_gran = 1; |
| 444 | |
| 445 | pde_get(&proc_root); |
| 446 | root_inode = proc_get_inode(s, &proc_root); |
| 447 | if (!root_inode) { |
| 448 | pr_err("proc_fill_super: get root inode failed\n"); |
| 449 | return -ENOMEM; |
| 450 | } |
| 451 | |
| 452 | s->s_root = d_make_root(root_inode); |
| 453 | if (!s->s_root) { |
| 454 | pr_err("proc_fill_super: allocate dentry failed\n"); |
| 455 | return -ENOMEM; |
| 456 | } |
| 457 | |
| 458 | return proc_setup_self(s); |
| 459 | } |