fs/stat.c

   1 /*
   2  *  linux/fs/stat.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6
   7 #include <linux/export.h>
   8 #include <linux/mm.h>
   9 #include <linux/errno.h>
  10 #include <linux/file.h>
  11 #include <linux/highuid.h>
  12 #include <linux/fs.h>
  13 #include <linux/namei.h>
  14 #include <linux/security.h>
  15 #include <linux/syscalls.h>
  16 #include <linux/pagemap.h>
  17
  18 #include <linux/uaccess.h>
  19 #include <asm/unistd.h>
  20
  21 void generic_fillattr(struct inode *inode, struct kstat *stat)
  22 {
  23         stat->dev = inode->i_sb->s_dev;
  24         stat->ino = inode->i_ino;
  25         stat->mode = inode->i_mode;
  26         stat->nlink = inode->i_nlink;
  27         stat->uid = inode->i_uid;
  28         stat->gid = inode->i_gid;
  29         stat->rdev = inode->i_rdev;
  30         stat->size = i_size_read(inode);
  31         stat->atime = inode->i_atime;
  32         stat->mtime = inode->i_mtime;
  33         stat->ctime = inode->i_ctime;
  34         stat->blksize = (1 << inode->i_blkbits);
  35         stat->blocks = inode->i_blocks;
  36 }
  37
  38 EXPORT_SYMBOL(generic_fillattr);
  39
  40 /**
  41  * vfs_getattr_nosec - getattr without security checks
  42  * @path: file to get attributes from
  43  * @stat: structure to return attributes in
  44  *
  45  * Get attributes without calling security_inode_getattr.
  46  *
  47  * Currently the only caller other than vfs_getattr is internal to the
  48  * filehandle lookup code, which uses only the inode number and returns
  49  * no attributes to any user.  Any other code probably wants
  50  * vfs_getattr.
  51  */
  52 int vfs_getattr_nosec(struct path *path, struct kstat *stat)
  53 {
  54         struct inode *inode = d_backing_inode(path->dentry);
  55
  56         if (inode->i_op->getattr)
  57                 return inode->i_op->getattr(path->mnt, path->dentry, stat);
  58
  59         generic_fillattr(inode, stat);
  60         return 0;
  61 }
  62
  63 EXPORT_SYMBOL(vfs_getattr_nosec);
  64
  65 int vfs_getattr(struct path *path, struct kstat *stat)
  66 {
  67         int retval;
  68
  69         retval = security_inode_getattr(path);
  70         if (retval)
  71                 return retval;
  72         return vfs_getattr_nosec(path, stat);
  73 }
  74
  75 EXPORT_SYMBOL(vfs_getattr);
  76
  77 int vfs_fstat(unsigned int fd, struct kstat *stat)
  78 {
  79         struct fd f = fdget_raw(fd);
  80         int error = -EBADF;
  81
  82         if (f.file) {
  83                 error = vfs_getattr(&f.file->f_path, stat);
  84                 fdput(f);
  85         }
  86         return error;
  87 }
  88 EXPORT_SYMBOL(vfs_fstat);
  89
  90 int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat,
  91                 int flag)
  92 {
  93         struct path path;
  94         int error = -EINVAL;
  95         unsigned int lookup_flags = 0;
  96
  97         if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT |
  98                       AT_EMPTY_PATH)) != 0)
  99                 goto out;
 100
 101         if (!(flag & AT_SYMLINK_NOFOLLOW))
 102                 lookup_flags |= LOOKUP_FOLLOW;
 103         if (flag & AT_EMPTY_PATH)
 104                 lookup_flags |= LOOKUP_EMPTY;
 105 retry:
 106         error = user_path_at(dfd, filename, lookup_flags, &path);
 107         if (error)
 108                 goto out;
 109
 110         error = vfs_getattr(&path, stat);
 111         path_put(&path);
 112         if (retry_estale(error, lookup_flags)) {
 113                 lookup_flags |= LOOKUP_REVAL;
 114                 goto retry;
 115         }
 116 out:
 117         return error;
 118 }
 119 EXPORT_SYMBOL(vfs_fstatat);
 120
 121 int vfs_stat(const char __user *name, struct kstat *stat)
 122 {
 123         return vfs_fstatat(AT_FDCWD, name, stat, 0);
 124 }
 125 EXPORT_SYMBOL(vfs_stat);
 126
 127 int vfs_lstat(const char __user *name, struct kstat *stat)
 128 {
 129         return vfs_fstatat(AT_FDCWD, name, stat, AT_SYMLINK_NOFOLLOW);
 130 }
 131 EXPORT_SYMBOL(vfs_lstat);
 132
 133
 134 #ifdef __ARCH_WANT_OLD_STAT
 135
 136 /*
 137  * For backward compatibility?  Maybe this should be moved
 138  * into arch/i386 instead?
 139  */
 140 static int cp_old_stat(struct kstat *stat, struct __old_kernel_stat __user * statbuf)
 141 {
 142         static int warncount = 5;
 143         struct __old_kernel_stat tmp;
 144
 145         if (warncount > 0) {
 146                 warncount--;
 147                 printk(KERN_WARNING "VFS: Warning: %s using old stat() call. Recompile your binary.\n",
 148                         current->comm);
 149         } else if (warncount < 0) {
 150                 /* it's laughable, but... */
 151                 warncount = 0;
 152         }
 153
 154         memset(&tmp, 0, sizeof(struct __old_kernel_stat));
 155         tmp.st_dev = old_encode_dev(stat->dev);
 156         tmp.st_ino = stat->ino;
 157         if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
 158                 return -EOVERFLOW;
 159         tmp.st_mode = stat->mode;
 160         tmp.st_nlink = stat->nlink;
 161         if (tmp.st_nlink != stat->nlink)
 162                 return -EOVERFLOW;
 163         SET_UID(tmp.st_uid, from_kuid_munged(current_user_ns(), stat->uid));
 164         SET_GID(tmp.st_gid, from_kgid_munged(current_user_ns(), stat->gid));
 165         tmp.st_rdev = old_encode_dev(stat->rdev);
 166 #if BITS_PER_LONG == 32
 167         if (stat->size > MAX_NON_LFS)
 168                 return -EOVERFLOW;
 169 #endif
 170         tmp.st_size = stat->size;
 171         tmp.st_atime = stat->atime.tv_sec;
 172         tmp.st_mtime = stat->mtime.tv_sec;
 173         tmp.st_ctime = stat->ctime.tv_sec;
 174         return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
 175 }
 176
 177 SYSCALL_DEFINE2(stat, const char __user *, filename,
 178                 struct __old_kernel_stat __user *, statbuf)
 179 {
 180         struct kstat stat;
 181         int error;
 182
 183         error = vfs_stat(filename, &stat);
 184         if (error)
 185                 return error;
 186
 187         return cp_old_stat(&stat, statbuf);
 188 }
 189
 190 SYSCALL_DEFINE2(lstat, const char __user *, filename,
 191                 struct __old_kernel_stat __user *, statbuf)
 192 {
 193         struct kstat stat;
 194         int error;
 195
 196         error = vfs_lstat(filename, &stat);
 197         if (error)
 198                 return error;
 199
 200         return cp_old_stat(&stat, statbuf);
 201 }
 202
 203 SYSCALL_DEFINE2(fstat, unsigned int, fd, struct __old_kernel_stat __user *, statbuf)
 204 {
 205         struct kstat stat;
 206         int error = vfs_fstat(fd, &stat);
 207
 208         if (!error)
 209                 error = cp_old_stat(&stat, statbuf);
 210
 211         return error;
 212 }
 213
 214 #endif /* __ARCH_WANT_OLD_STAT */
 215
 216 #if BITS_PER_LONG == 32
 217 #  define choose_32_64(a,b) a
 218 #else
 219 #  define choose_32_64(a,b) b
 220 #endif
 221
 222 #define valid_dev(x)  choose_32_64(old_valid_dev(x),true)
 223 #define encode_dev(x) choose_32_64(old_encode_dev,new_encode_dev)(x)
 224
 225 #ifndef INIT_STRUCT_STAT_PADDING
 226 #  define INIT_STRUCT_STAT_PADDING(st) memset(&st, 0, sizeof(st))
 227 #endif
 228
 229 static int cp_new_stat(struct kstat *stat, struct stat __user *statbuf)
 230 {
 231         struct stat tmp;
 232
 233         if (!valid_dev(stat->dev) || !valid_dev(stat->rdev))
 234                 return -EOVERFLOW;
 235 #if BITS_PER_LONG == 32
 236         if (stat->size > MAX_NON_LFS)
 237                 return -EOVERFLOW;
 238 #endif
 239
 240         INIT_STRUCT_STAT_PADDING(tmp);
 241         tmp.st_dev = encode_dev(stat->dev);
 242         tmp.st_ino = stat->ino;
 243         if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
 244                 return -EOVERFLOW;
 245         tmp.st_mode = stat->mode;
 246         tmp.st_nlink = stat->nlink;
 247         if (tmp.st_nlink != stat->nlink)
 248                 return -EOVERFLOW;
 249         SET_UID(tmp.st_uid, from_kuid_munged(current_user_ns(), stat->uid));
 250         SET_GID(tmp.st_gid, from_kgid_munged(current_user_ns(), stat->gid));
 251         tmp.st_rdev = encode_dev(stat->rdev);
 252         tmp.st_size = stat->size;
 253         tmp.st_atime = stat->atime.tv_sec;
 254         tmp.st_mtime = stat->mtime.tv_sec;
 255         tmp.st_ctime = stat->ctime.tv_sec;
 256 #ifdef STAT_HAVE_NSEC
 257         tmp.st_atime_nsec = stat->atime.tv_nsec;
 258         tmp.st_mtime_nsec = stat->mtime.tv_nsec;
 259         tmp.st_ctime_nsec = stat->ctime.tv_nsec;
 260 #endif
 261         tmp.st_blocks = stat->blocks;
 262         tmp.st_blksize = stat->blksize;
 263         return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
 264 }
 265
 266 SYSCALL_DEFINE2(newstat, const char __user *, filename,
 267                 struct stat __user *, statbuf)
 268 {
 269         struct kstat stat;
 270         int error = vfs_stat(filename, &stat);
 271
 272         if (error)
 273                 return error;
 274         return cp_new_stat(&stat, statbuf);
 275 }
 276
 277 SYSCALL_DEFINE2(newlstat, const char __user *, filename,
 278                 struct stat __user *, statbuf)
 279 {
 280         struct kstat stat;
 281         int error;
 282
 283         error = vfs_lstat(filename, &stat);
 284         if (error)
 285                 return error;
 286
 287         return cp_new_stat(&stat, statbuf);
 288 }
 289
 290 #if !defined(__ARCH_WANT_STAT64) || defined(__ARCH_WANT_SYS_NEWFSTATAT)
 291 SYSCALL_DEFINE4(newfstatat, int, dfd, const char __user *, filename,
 292                 struct stat __user *, statbuf, int, flag)
 293 {
 294         struct kstat stat;
 295         int error;
 296
 297         error = vfs_fstatat(dfd, filename, &stat, flag);
 298         if (error)
 299                 return error;
 300         return cp_new_stat(&stat, statbuf);
 301 }
 302 #endif
 303
 304 SYSCALL_DEFINE2(newfstat, unsigned int, fd, struct stat __user *, statbuf)
 305 {
 306         struct kstat stat;
 307         int error = vfs_fstat(fd, &stat);
 308
 309         if (!error)
 310                 error = cp_new_stat(&stat, statbuf);
 311
 312         return error;
 313 }
 314
 315 SYSCALL_DEFINE4(readlinkat, int, dfd, const char __user *, pathname,
 316                 char __user *, buf, int, bufsiz)
 317 {
 318         struct path path;
 319         int error;
 320         int empty = 0;
 321         unsigned int lookup_flags = LOOKUP_EMPTY;
 322
 323         if (bufsiz <= 0)
 324                 return -EINVAL;
 325
 326 retry:
 327         error = user_path_at_empty(dfd, pathname, lookup_flags, &path, &empty);
 328         if (!error) {
 329                 struct inode *inode = d_backing_inode(path.dentry);
 330
 331                 error = empty ? -ENOENT : -EINVAL;
 332                 /*
 333                  * AFS mountpoints allow readlink(2) but are not symlinks
 334                  */
 335                 if (d_is_symlink(path.dentry) || inode->i_op->readlink) {
 336                         error = security_inode_readlink(path.dentry);
 337                         if (!error) {
 338                                 touch_atime(&path);
 339                                 error = vfs_readlink(path.dentry, buf, bufsiz);
 340                         }
 341                 }
 342                 path_put(&path);
 343                 if (retry_estale(error, lookup_flags)) {
 344                         lookup_flags |= LOOKUP_REVAL;
 345                         goto retry;
 346                 }
 347         }
 348         return error;
 349 }
 350
 351 SYSCALL_DEFINE3(readlink, const char __user *, path, char __user *, buf,
 352                 int, bufsiz)
 353 {
 354         return sys_readlinkat(AT_FDCWD, path, buf, bufsiz);
 355 }
 356
 357
 358 /* ---------- LFS-64 ----------- */
 359 #if defined(__ARCH_WANT_STAT64) || defined(__ARCH_WANT_COMPAT_STAT64)
 360
 361 #ifndef INIT_STRUCT_STAT64_PADDING
 362 #  define INIT_STRUCT_STAT64_PADDING(st) memset(&st, 0, sizeof(st))
 363 #endif
 364
 365 static long cp_new_stat64(struct kstat *stat, struct stat64 __user *statbuf)
 366 {
 367         struct stat64 tmp;
 368
 369         INIT_STRUCT_STAT64_PADDING(tmp);
 370 #ifdef CONFIG_MIPS
 371         /* mips has weird padding, so we don't get 64 bits there */
 372         tmp.st_dev = new_encode_dev(stat->dev);
 373         tmp.st_rdev = new_encode_dev(stat->rdev);
 374 #else
 375         tmp.st_dev = huge_encode_dev(stat->dev);
 376         tmp.st_rdev = huge_encode_dev(stat->rdev);
 377 #endif
 378         tmp.st_ino = stat->ino;
 379         if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
 380                 return -EOVERFLOW;
 381 #ifdef STAT64_HAS_BROKEN_ST_INO
 382         tmp.__st_ino = stat->ino;
 383 #endif
 384         tmp.st_mode = stat->mode;
 385         tmp.st_nlink = stat->nlink;
 386         tmp.st_uid = from_kuid_munged(current_user_ns(), stat->uid);
 387         tmp.st_gid = from_kgid_munged(current_user_ns(), stat->gid);
 388         tmp.st_atime = stat->atime.tv_sec;
 389         tmp.st_atime_nsec = stat->atime.tv_nsec;
 390         tmp.st_mtime = stat->mtime.tv_sec;
 391         tmp.st_mtime_nsec = stat->mtime.tv_nsec;
 392         tmp.st_ctime = stat->ctime.tv_sec;
 393         tmp.st_ctime_nsec = stat->ctime.tv_nsec;
 394         tmp.st_size = stat->size;
 395         tmp.st_blocks = stat->blocks;
 396         tmp.st_blksize = stat->blksize;
 397         return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
 398 }
 399
 400 SYSCALL_DEFINE2(stat64, const char __user *, filename,
 401                 struct stat64 __user *, statbuf)
 402 {
 403         struct kstat stat;
 404         int error = vfs_stat(filename, &stat);
 405
 406         if (!error)
 407                 error = cp_new_stat64(&stat, statbuf);
 408
 409         return error;
 410 }
 411
 412 SYSCALL_DEFINE2(lstat64, const char __user *, filename,
 413                 struct stat64 __user *, statbuf)
 414 {
 415         struct kstat stat;
 416         int error = vfs_lstat(filename, &stat);
 417
 418         if (!error)
 419                 error = cp_new_stat64(&stat, statbuf);
 420
 421         return error;
 422 }
 423
 424 SYSCALL_DEFINE2(fstat64, unsigned long, fd, struct stat64 __user *, statbuf)
 425 {
 426         struct kstat stat;
 427         int error = vfs_fstat(fd, &stat);
 428
 429         if (!error)
 430                 error = cp_new_stat64(&stat, statbuf);
 431
 432         return error;
 433 }
 434
 435 SYSCALL_DEFINE4(fstatat64, int, dfd, const char __user *, filename,
 436                 struct stat64 __user *, statbuf, int, flag)
 437 {
 438         struct kstat stat;
 439         int error;
 440
 441         error = vfs_fstatat(dfd, filename, &stat, flag);
 442         if (error)
 443                 return error;
 444         return cp_new_stat64(&stat, statbuf);
 445 }
 446 #endif /* __ARCH_WANT_STAT64 || __ARCH_WANT_COMPAT_STAT64 */
 447
 448 /* Caller is here responsible for sufficient locking (ie. inode->i_lock) */
 449 void __inode_add_bytes(struct inode *inode, loff_t bytes)
 450 {
 451         inode->i_blocks += bytes >> 9;
 452         bytes &= 511;
 453         inode->i_bytes += bytes;
 454         if (inode->i_bytes >= 512) {
 455                 inode->i_blocks++;
 456                 inode->i_bytes -= 512;
 457         }
 458 }
 459
 460 void inode_add_bytes(struct inode *inode, loff_t bytes)
 461 {
 462         spin_lock(&inode->i_lock);
 463         __inode_add_bytes(inode, bytes);
 464         spin_unlock(&inode->i_lock);
 465 }
 466
 467 EXPORT_SYMBOL(inode_add_bytes);
 468
 469 void __inode_sub_bytes(struct inode *inode, loff_t bytes)
 470 {
 471         inode->i_blocks -= bytes >> 9;
 472         bytes &= 511;
 473         if (inode->i_bytes < bytes) {
 474                 inode->i_blocks--;
 475                 inode->i_bytes += 512;
 476         }
 477         inode->i_bytes -= bytes;
 478 }
 479
 480 EXPORT_SYMBOL(__inode_sub_bytes);
 481
 482 void inode_sub_bytes(struct inode *inode, loff_t bytes)
 483 {
 484         spin_lock(&inode->i_lock);
 485         __inode_sub_bytes(inode, bytes);
 486         spin_unlock(&inode->i_lock);
 487 }
 488
 489 EXPORT_SYMBOL(inode_sub_bytes);
 490
 491 loff_t inode_get_bytes(struct inode *inode)
 492 {
 493         loff_t ret;
 494
 495         spin_lock(&inode->i_lock);
 496         ret = (((loff_t)inode->i_blocks) << 9) + inode->i_bytes;
 497         spin_unlock(&inode->i_lock);
 498         return ret;
 499 }
 500
 501 EXPORT_SYMBOL(inode_get_bytes);
 502
 503 void inode_set_bytes(struct inode *inode, loff_t bytes)
 504 {
 505         /* Caller is here responsible for sufficient locking
 506          * (ie. inode->i_lock) */
 507         inode->i_blocks = bytes >> 9;
 508         inode->i_bytes = bytes & 511;
 509 }
 510
 511 EXPORT_SYMBOL(inode_set_bytes);