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