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