fs/open.c

   1 /*
   2  *  linux/fs/open.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6
   7 #include <linux/string.h>
   8 #include <linux/mm.h>
   9 #include <linux/utime.h>
  10 #include <linux/file.h>
  11 #include <linux/smp_lock.h>
  12 #include <linux/quotaops.h>
  13 #include <linux/fsnotify.h>
  14 #include <linux/module.h>
  15 #include <linux/slab.h>
  16 #include <linux/tty.h>
  17 #include <linux/namei.h>
  18 #include <linux/backing-dev.h>
  19 #include <linux/security.h>
  20 #include <linux/mount.h>
  21 #include <linux/vfs.h>
  22 #include <asm/uaccess.h>
  23 #include <linux/fs.h>
  24 #include <linux/personality.h>
  25 #include <linux/pagemap.h>
  26 #include <linux/syscalls.h>
  27 #include <linux/rcupdate.h>
  28
  29 #include <asm/unistd.h>
  30
  31 int vfs_statfs(struct super_block *sb, struct kstatfs *buf)
  32 {
  33         int retval = -ENODEV;
  34
  35         if (sb) {
  36                 retval = -ENOSYS;
  37                 if (sb->s_op->statfs) {
  38                         memset(buf, 0, sizeof(*buf));
  39                         retval = security_sb_statfs(sb);
  40                         if (retval)
  41                                 return retval;
  42                         retval = sb->s_op->statfs(sb, buf);
  43                         if (retval == 0 && buf->f_frsize == 0)
  44                                 buf->f_frsize = buf->f_bsize;
  45                 }
  46         }
  47         return retval;
  48 }
  49
  50 EXPORT_SYMBOL(vfs_statfs);
  51
  52 static int vfs_statfs_native(struct super_block *sb, struct statfs *buf)
  53 {
  54         struct kstatfs st;
  55         int retval;
  56
  57         retval = vfs_statfs(sb, &st);
  58         if (retval)
  59                 return retval;
  60
  61         if (sizeof(*buf) == sizeof(st))
  62                 memcpy(buf, &st, sizeof(st));
  63         else {
  64                 if (sizeof buf->f_blocks == 4) {
  65                         if ((st.f_blocks | st.f_bfree | st.f_bavail) &
  66                             0xffffffff00000000ULL)
  67                                 return -EOVERFLOW;
  68                         /*
  69                          * f_files and f_ffree may be -1; it's okay to stuff
  70                          * that into 32 bits
  71                          */
  72                         if (st.f_files != -1 &&
  73                             (st.f_files & 0xffffffff00000000ULL))
  74                                 return -EOVERFLOW;
  75                         if (st.f_ffree != -1 &&
  76                             (st.f_ffree & 0xffffffff00000000ULL))
  77                                 return -EOVERFLOW;
  78                 }
  79
  80                 buf->f_type = st.f_type;
  81                 buf->f_bsize = st.f_bsize;
  82                 buf->f_blocks = st.f_blocks;
  83                 buf->f_bfree = st.f_bfree;
  84                 buf->f_bavail = st.f_bavail;
  85                 buf->f_files = st.f_files;
  86                 buf->f_ffree = st.f_ffree;
  87                 buf->f_fsid = st.f_fsid;
  88                 buf->f_namelen = st.f_namelen;
  89                 buf->f_frsize = st.f_frsize;
  90                 memset(buf->f_spare, 0, sizeof(buf->f_spare));
  91         }
  92         return 0;
  93 }
  94
  95 static int vfs_statfs64(struct super_block *sb, struct statfs64 *buf)
  96 {
  97         struct kstatfs st;
  98         int retval;
  99
 100         retval = vfs_statfs(sb, &st);
 101         if (retval)
 102                 return retval;
 103
 104         if (sizeof(*buf) == sizeof(st))
 105                 memcpy(buf, &st, sizeof(st));
 106         else {
 107                 buf->f_type = st.f_type;
 108                 buf->f_bsize = st.f_bsize;
 109                 buf->f_blocks = st.f_blocks;
 110                 buf->f_bfree = st.f_bfree;
 111                 buf->f_bavail = st.f_bavail;
 112                 buf->f_files = st.f_files;
 113                 buf->f_ffree = st.f_ffree;
 114                 buf->f_fsid = st.f_fsid;
 115                 buf->f_namelen = st.f_namelen;
 116                 buf->f_frsize = st.f_frsize;
 117                 memset(buf->f_spare, 0, sizeof(buf->f_spare));
 118         }
 119         return 0;
 120 }
 121
 122 asmlinkage long sys_statfs(const char __user * path, struct statfs __user * buf)
 123 {
 124         struct nameidata nd;
 125         int error;
 126
 127         error = user_path_walk(path, &nd);
 128         if (!error) {
 129                 struct statfs tmp;
 130                 error = vfs_statfs_native(nd.dentry->d_inode->i_sb, &tmp);
 131                 if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
 132                         error = -EFAULT;
 133                 path_release(&nd);
 134         }
 135         return error;
 136 }
 137
 138
 139 asmlinkage long sys_statfs64(const char __user *path, size_t sz, struct statfs64 __user *buf)
 140 {
 141         struct nameidata nd;
 142         long error;
 143
 144         if (sz != sizeof(*buf))
 145                 return -EINVAL;
 146         error = user_path_walk(path, &nd);
 147         if (!error) {
 148                 struct statfs64 tmp;
 149                 error = vfs_statfs64(nd.dentry->d_inode->i_sb, &tmp);
 150                 if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
 151                         error = -EFAULT;
 152                 path_release(&nd);
 153         }
 154         return error;
 155 }
 156
 157
 158 asmlinkage long sys_fstatfs(unsigned int fd, struct statfs __user * buf)
 159 {
 160         struct file * file;
 161         struct statfs tmp;
 162         int error;
 163
 164         error = -EBADF;
 165         file = fget(fd);
 166         if (!file)
 167                 goto out;
 168         error = vfs_statfs_native(file->f_dentry->d_inode->i_sb, &tmp);
 169         if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
 170                 error = -EFAULT;
 171         fput(file);
 172 out:
 173         return error;
 174 }
 175
 176 asmlinkage long sys_fstatfs64(unsigned int fd, size_t sz, struct statfs64 __user *buf)
 177 {
 178         struct file * file;
 179         struct statfs64 tmp;
 180         int error;
 181
 182         if (sz != sizeof(*buf))
 183                 return -EINVAL;
 184
 185         error = -EBADF;
 186         file = fget(fd);
 187         if (!file)
 188                 goto out;
 189         error = vfs_statfs64(file->f_dentry->d_inode->i_sb, &tmp);
 190         if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
 191                 error = -EFAULT;
 192         fput(file);
 193 out:
 194         return error;
 195 }
 196
 197 int do_truncate(struct dentry *dentry, loff_t length)
 198 {
 199         int err;
 200         struct iattr newattrs;
 201
 202         /* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
 203         if (length < 0)
 204                 return -EINVAL;
 205
 206         newattrs.ia_size = length;
 207         newattrs.ia_valid = ATTR_SIZE | ATTR_CTIME;
 208
 209         down(&dentry->d_inode->i_sem);
 210         err = notify_change(dentry, &newattrs);
 211         up(&dentry->d_inode->i_sem);
 212         return err;
 213 }
 214
 215 static inline long do_sys_truncate(const char __user * path, loff_t length)
 216 {
 217         struct nameidata nd;
 218         struct inode * inode;
 219         int error;
 220
 221         error = -EINVAL;
 222         if (length < 0) /* sorry, but loff_t says... */
 223                 goto out;
 224
 225         error = user_path_walk(path, &nd);
 226         if (error)
 227                 goto out;
 228         inode = nd.dentry->d_inode;
 229
 230         /* For directories it's -EISDIR, for other non-regulars - -EINVAL */
 231         error = -EISDIR;
 232         if (S_ISDIR(inode->i_mode))
 233                 goto dput_and_out;
 234
 235         error = -EINVAL;
 236         if (!S_ISREG(inode->i_mode))
 237                 goto dput_and_out;
 238
 239         error = permission(inode,MAY_WRITE,&nd);
 240         if (error)
 241                 goto dput_and_out;
 242
 243         error = -EROFS;
 244         if (IS_RDONLY(inode))
 245                 goto dput_and_out;
 246
 247         error = -EPERM;
 248         if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
 249                 goto dput_and_out;
 250
 251         /*
 252          * Make sure that there are no leases.
 253          */
 254         error = break_lease(inode, FMODE_WRITE);
 255         if (error)
 256                 goto dput_and_out;
 257
 258         error = get_write_access(inode);
 259         if (error)
 260                 goto dput_and_out;
 261
 262         error = locks_verify_truncate(inode, NULL, length);
 263         if (!error) {
 264                 DQUOT_INIT(inode);
 265                 error = do_truncate(nd.dentry, length);
 266         }
 267         put_write_access(inode);
 268
 269 dput_and_out:
 270         path_release(&nd);
 271 out:
 272         return error;
 273 }
 274
 275 asmlinkage long sys_truncate(const char __user * path, unsigned long length)
 276 {
 277         /* on 32-bit boxen it will cut the range 2^31--2^32-1 off */
 278         return do_sys_truncate(path, (long)length);
 279 }
 280
 281 static inline long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
 282 {
 283         struct inode * inode;
 284         struct dentry *dentry;
 285         struct file * file;
 286         int error;
 287
 288         error = -EINVAL;
 289         if (length < 0)
 290                 goto out;
 291         error = -EBADF;
 292         file = fget(fd);
 293         if (!file)
 294                 goto out;
 295
 296         /* explicitly opened as large or we are on 64-bit box */
 297         if (file->f_flags & O_LARGEFILE)
 298                 small = 0;
 299
 300         dentry = file->f_dentry;
 301         inode = dentry->d_inode;
 302         error = -EINVAL;
 303         if (!S_ISREG(inode->i_mode) || !(file->f_mode & FMODE_WRITE))
 304                 goto out_putf;
 305
 306         error = -EINVAL;
 307         /* Cannot ftruncate over 2^31 bytes without large file support */
 308         if (small && length > MAX_NON_LFS)
 309                 goto out_putf;
 310
 311         error = -EPERM;
 312         if (IS_APPEND(inode))
 313                 goto out_putf;
 314
 315         error = locks_verify_truncate(inode, file, length);
 316         if (!error)
 317                 error = do_truncate(dentry, length);
 318 out_putf:
 319         fput(file);
 320 out:
 321         return error;
 322 }
 323
 324 asmlinkage long sys_ftruncate(unsigned int fd, unsigned long length)
 325 {
 326         return do_sys_ftruncate(fd, length, 1);
 327 }
 328
 329 /* LFS versions of truncate are only needed on 32 bit machines */
 330 #if BITS_PER_LONG == 32
 331 asmlinkage long sys_truncate64(const char __user * path, loff_t length)
 332 {
 333         return do_sys_truncate(path, length);
 334 }
 335
 336 asmlinkage long sys_ftruncate64(unsigned int fd, loff_t length)
 337 {
 338         return do_sys_ftruncate(fd, length, 0);
 339 }
 340 #endif
 341
 342 #ifdef __ARCH_WANT_SYS_UTIME
 343
 344 /*
 345  * sys_utime() can be implemented in user-level using sys_utimes().
 346  * Is this for backwards compatibility?  If so, why not move it
 347  * into the appropriate arch directory (for those architectures that
 348  * need it).
 349  */
 350
 351 /* If times==NULL, set access and modification to current time,
 352  * must be owner or have write permission.
 353  * Else, update from *times, must be owner or super user.
 354  */
 355 asmlinkage long sys_utime(char __user * filename, struct utimbuf __user * times)
 356 {
 357         int error;
 358         struct nameidata nd;
 359         struct inode * inode;
 360         struct iattr newattrs;
 361
 362         error = user_path_walk(filename, &nd);
 363         if (error)
 364                 goto out;
 365         inode = nd.dentry->d_inode;
 366
 367         error = -EROFS;
 368         if (IS_RDONLY(inode))
 369                 goto dput_and_out;
 370
 371         /* Don't worry, the checks are done in inode_change_ok() */
 372         newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
 373         if (times) {
 374                 error = -EPERM;
 375                 if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
 376                         goto dput_and_out;
 377
 378                 error = get_user(newattrs.ia_atime.tv_sec, &times->actime);
 379                 newattrs.ia_atime.tv_nsec = 0;
 380                 if (!error)
 381                         error = get_user(newattrs.ia_mtime.tv_sec, &times->modtime);
 382                 newattrs.ia_mtime.tv_nsec = 0;
 383                 if (error)
 384                         goto dput_and_out;
 385
 386                 newattrs.ia_valid |= ATTR_ATIME_SET | ATTR_MTIME_SET;
 387         } else {
 388                 error = -EACCES;
 389                 if (IS_IMMUTABLE(inode))
 390                         goto dput_and_out;
 391
 392                 if (current->fsuid != inode->i_uid &&
 393                     (error = permission(inode,MAY_WRITE,&nd)) != 0)
 394                         goto dput_and_out;
 395         }
 396         down(&inode->i_sem);
 397         error = notify_change(nd.dentry, &newattrs);
 398         up(&inode->i_sem);
 399 dput_and_out:
 400         path_release(&nd);
 401 out:
 402         return error;
 403 }
 404
 405 #endif
 406
 407 /* If times==NULL, set access and modification to current time,
 408  * must be owner or have write permission.
 409  * Else, update from *times, must be owner or super user.
 410  */
 411 long do_utimes(char __user * filename, struct timeval * times)
 412 {
 413         int error;
 414         struct nameidata nd;
 415         struct inode * inode;
 416         struct iattr newattrs;
 417
 418         error = user_path_walk(filename, &nd);
 419
 420         if (error)
 421                 goto out;
 422         inode = nd.dentry->d_inode;
 423
 424         error = -EROFS;
 425         if (IS_RDONLY(inode))
 426                 goto dput_and_out;
 427
 428         /* Don't worry, the checks are done in inode_change_ok() */
 429         newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
 430         if (times) {
 431                 error = -EPERM;
 432                 if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
 433                         goto dput_and_out;
 434
 435                 newattrs.ia_atime.tv_sec = times[0].tv_sec;
 436                 newattrs.ia_atime.tv_nsec = times[0].tv_usec * 1000;
 437                 newattrs.ia_mtime.tv_sec = times[1].tv_sec;
 438                 newattrs.ia_mtime.tv_nsec = times[1].tv_usec * 1000;
 439                 newattrs.ia_valid |= ATTR_ATIME_SET | ATTR_MTIME_SET;
 440         } else {
 441                 error = -EACCES;
 442                 if (IS_IMMUTABLE(inode))
 443                         goto dput_and_out;
 444
 445                 if (current->fsuid != inode->i_uid &&
 446                     (error = permission(inode,MAY_WRITE,&nd)) != 0)
 447                         goto dput_and_out;
 448         }
 449         down(&inode->i_sem);
 450         error = notify_change(nd.dentry, &newattrs);
 451         up(&inode->i_sem);
 452 dput_and_out:
 453         path_release(&nd);
 454 out:
 455         return error;
 456 }
 457
 458 asmlinkage long sys_utimes(char __user * filename, struct timeval __user * utimes)
 459 {
 460         struct timeval times[2];
 461
 462         if (utimes && copy_from_user(&times, utimes, sizeof(times)))
 463                 return -EFAULT;
 464         return do_utimes(filename, utimes ? times : NULL);
 465 }
 466
 467
 468 /*
 469  * access() needs to use the real uid/gid, not the effective uid/gid.
 470  * We do this by temporarily clearing all FS-related capabilities and
 471  * switching the fsuid/fsgid around to the real ones.
 472  */
 473 asmlinkage long sys_access(const char __user * filename, int mode)
 474 {
 475         struct nameidata nd;
 476         int old_fsuid, old_fsgid;
 477         kernel_cap_t old_cap;
 478         int res;
 479
 480         if (mode & ~S_IRWXO)    /* where's F_OK, X_OK, W_OK, R_OK? */
 481                 return -EINVAL;
 482
 483         old_fsuid = current->fsuid;
 484         old_fsgid = current->fsgid;
 485         old_cap = current->cap_effective;
 486
 487         current->fsuid = current->uid;
 488         current->fsgid = current->gid;
 489
 490         /*
 491          * Clear the capabilities if we switch to a non-root user
 492          *
 493          * FIXME: There is a race here against sys_capset.  The
 494          * capabilities can change yet we will restore the old
 495          * value below.  We should hold task_capabilities_lock,
 496          * but we cannot because user_path_walk can sleep.
 497          */
 498         if (current->uid)
 499                 cap_clear(current->cap_effective);
 500         else
 501                 current->cap_effective = current->cap_permitted;
 502
 503         res = __user_walk(filename, LOOKUP_FOLLOW|LOOKUP_ACCESS, &nd);
 504         if (!res) {
 505                 res = permission(nd.dentry->d_inode, mode, &nd);
 506                 /* SuS v2 requires we report a read only fs too */
 507                 if(!res && (mode & S_IWOTH) && IS_RDONLY(nd.dentry->d_inode)
 508                    && !special_file(nd.dentry->d_inode->i_mode))
 509                         res = -EROFS;
 510                 path_release(&nd);
 511         }
 512
 513         current->fsuid = old_fsuid;
 514         current->fsgid = old_fsgid;
 515         current->cap_effective = old_cap;
 516
 517         return res;
 518 }
 519
 520 asmlinkage long sys_chdir(const char __user * filename)
 521 {
 522         struct nameidata nd;
 523         int error;
 524
 525         error = __user_walk(filename, LOOKUP_FOLLOW|LOOKUP_DIRECTORY, &nd);
 526         if (error)
 527                 goto out;
 528
 529         error = permission(nd.dentry->d_inode,MAY_EXEC,&nd);
 530         if (error)
 531                 goto dput_and_out;
 532
 533         set_fs_pwd(current->fs, nd.mnt, nd.dentry);
 534
 535 dput_and_out:
 536         path_release(&nd);
 537 out:
 538         return error;
 539 }
 540
 541 asmlinkage long sys_fchdir(unsigned int fd)
 542 {
 543         struct file *file;
 544         struct dentry *dentry;
 545         struct inode *inode;
 546         struct vfsmount *mnt;
 547         int error;
 548
 549         error = -EBADF;
 550         file = fget(fd);
 551         if (!file)
 552                 goto out;
 553
 554         dentry = file->f_dentry;
 555         mnt = file->f_vfsmnt;
 556         inode = dentry->d_inode;
 557
 558         error = -ENOTDIR;
 559         if (!S_ISDIR(inode->i_mode))
 560                 goto out_putf;
 561
 562         error = permission(inode, MAY_EXEC, NULL);
 563         if (!error)
 564                 set_fs_pwd(current->fs, mnt, dentry);
 565 out_putf:
 566         fput(file);
 567 out:
 568         return error;
 569 }
 570
 571 asmlinkage long sys_chroot(const char __user * filename)
 572 {
 573         struct nameidata nd;
 574         int error;
 575
 576         error = __user_walk(filename, LOOKUP_FOLLOW | LOOKUP_DIRECTORY | LOOKUP_NOALT, &nd);
 577         if (error)
 578                 goto out;
 579
 580         error = permission(nd.dentry->d_inode,MAY_EXEC,&nd);
 581         if (error)
 582                 goto dput_and_out;
 583
 584         error = -EPERM;
 585         if (!capable(CAP_SYS_CHROOT))
 586                 goto dput_and_out;
 587
 588         set_fs_root(current->fs, nd.mnt, nd.dentry);
 589         set_fs_altroot();
 590         error = 0;
 591 dput_and_out:
 592         path_release(&nd);
 593 out:
 594         return error;
 595 }
 596
 597 asmlinkage long sys_fchmod(unsigned int fd, mode_t mode)
 598 {
 599         struct inode * inode;
 600         struct dentry * dentry;
 601         struct file * file;
 602         int err = -EBADF;
 603         struct iattr newattrs;
 604
 605         file = fget(fd);
 606         if (!file)
 607                 goto out;
 608
 609         dentry = file->f_dentry;
 610         inode = dentry->d_inode;
 611
 612         err = -EROFS;
 613         if (IS_RDONLY(inode))
 614                 goto out_putf;
 615         err = -EPERM;
 616         if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
 617                 goto out_putf;
 618         down(&inode->i_sem);
 619         if (mode == (mode_t) -1)
 620                 mode = inode->i_mode;
 621         newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
 622         newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
 623         err = notify_change(dentry, &newattrs);
 624         up(&inode->i_sem);
 625
 626 out_putf:
 627         fput(file);
 628 out:
 629         return err;
 630 }
 631
 632 asmlinkage long sys_chmod(const char __user * filename, mode_t mode)
 633 {
 634         struct nameidata nd;
 635         struct inode * inode;
 636         int error;
 637         struct iattr newattrs;
 638
 639         error = user_path_walk(filename, &nd);
 640         if (error)
 641                 goto out;
 642         inode = nd.dentry->d_inode;
 643
 644         error = -EROFS;
 645         if (IS_RDONLY(inode))
 646                 goto dput_and_out;
 647
 648         error = -EPERM;
 649         if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
 650                 goto dput_and_out;
 651
 652         down(&inode->i_sem);
 653         if (mode == (mode_t) -1)
 654                 mode = inode->i_mode;
 655         newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
 656         newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
 657         error = notify_change(nd.dentry, &newattrs);
 658         up(&inode->i_sem);
 659
 660 dput_and_out:
 661         path_release(&nd);
 662 out:
 663         return error;
 664 }
 665
 666 static int chown_common(struct dentry * dentry, uid_t user, gid_t group)
 667 {
 668         struct inode * inode;
 669         int error;
 670         struct iattr newattrs;
 671
 672         error = -ENOENT;
 673         if (!(inode = dentry->d_inode)) {
 674                 printk(KERN_ERR "chown_common: NULL inode\n");
 675                 goto out;
 676         }
 677         error = -EROFS;
 678         if (IS_RDONLY(inode))
 679                 goto out;
 680         error = -EPERM;
 681         if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
 682                 goto out;
 683         newattrs.ia_valid =  ATTR_CTIME;
 684         if (user != (uid_t) -1) {
 685                 newattrs.ia_valid |= ATTR_UID;
 686                 newattrs.ia_uid = user;
 687         }
 688         if (group != (gid_t) -1) {
 689                 newattrs.ia_valid |= ATTR_GID;
 690                 newattrs.ia_gid = group;
 691         }
 692         if (!S_ISDIR(inode->i_mode))
 693                 newattrs.ia_valid |= ATTR_KILL_SUID|ATTR_KILL_SGID;
 694         down(&inode->i_sem);
 695         error = notify_change(dentry, &newattrs);
 696         up(&inode->i_sem);
 697 out:
 698         return error;
 699 }
 700
 701 asmlinkage long sys_chown(const char __user * filename, uid_t user, gid_t group)
 702 {
 703         struct nameidata nd;
 704         int error;
 705
 706         error = user_path_walk(filename, &nd);
 707         if (!error) {
 708                 error = chown_common(nd.dentry, user, group);
 709                 path_release(&nd);
 710         }
 711         return error;
 712 }
 713
 714 asmlinkage long sys_lchown(const char __user * filename, uid_t user, gid_t group)
 715 {
 716         struct nameidata nd;
 717         int error;
 718
 719         error = user_path_walk_link(filename, &nd);
 720         if (!error) {
 721                 error = chown_common(nd.dentry, user, group);
 722                 path_release(&nd);
 723         }
 724         return error;
 725 }
 726
 727
 728 asmlinkage long sys_fchown(unsigned int fd, uid_t user, gid_t group)
 729 {
 730         struct file * file;
 731         int error = -EBADF;
 732
 733         file = fget(fd);
 734         if (file) {
 735                 error = chown_common(file->f_dentry, user, group);
 736                 fput(file);
 737         }
 738         return error;
 739 }
 740
 741 static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
 742                                         int flags, struct file *f)
 743 {
 744         struct inode *inode;
 745         int error;
 746
 747         f->f_flags = flags;
 748         f->f_mode = ((flags+1) & O_ACCMODE) | FMODE_LSEEK |
 749                                 FMODE_PREAD | FMODE_PWRITE;
 750         inode = dentry->d_inode;
 751         if (f->f_mode & FMODE_WRITE) {
 752                 error = get_write_access(inode);
 753                 if (error)
 754                         goto cleanup_file;
 755         }
 756
 757         f->f_mapping = inode->i_mapping;
 758         f->f_dentry = dentry;
 759         f->f_vfsmnt = mnt;
 760         f->f_pos = 0;
 761         f->f_op = fops_get(inode->i_fop);
 762         file_move(f, &inode->i_sb->s_files);
 763
 764         if (f->f_op && f->f_op->open) {
 765                 error = f->f_op->open(inode,f);
 766                 if (error)
 767                         goto cleanup_all;
 768         }
 769         f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
 770
 771         file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
 772
 773         /* NB: we're sure to have correct a_ops only after f_op->open */
 774         if (f->f_flags & O_DIRECT) {
 775                 if (!f->f_mapping->a_ops ||
 776                     ((!f->f_mapping->a_ops->direct_IO) &&
 777                     (!f->f_mapping->a_ops->get_xip_page))) {
 778                         fput(f);
 779                         f = ERR_PTR(-EINVAL);
 780                 }
 781         }
 782
 783         return f;
 784
 785 cleanup_all:
 786         fops_put(f->f_op);
 787         if (f->f_mode & FMODE_WRITE)
 788                 put_write_access(inode);
 789         file_kill(f);
 790         f->f_dentry = NULL;
 791         f->f_vfsmnt = NULL;
 792 cleanup_file:
 793         put_filp(f);
 794         dput(dentry);
 795         mntput(mnt);
 796         return ERR_PTR(error);
 797 }
 798
 799 /*
 800  * Note that while the flag value (low two bits) for sys_open means:
 801  *      00 - read-only
 802  *      01 - write-only
 803  *      10 - read-write
 804  *      11 - special
 805  * it is changed into
 806  *      00 - no permissions needed
 807  *      01 - read-permission
 808  *      10 - write-permission
 809  *      11 - read-write
 810  * for the internal routines (ie open_namei()/follow_link() etc). 00 is
 811  * used by symlinks.
 812  */
 813 struct file *filp_open(const char * filename, int flags, int mode)
 814 {
 815         int namei_flags, error;
 816         struct nameidata nd;
 817         struct file *f;
 818
 819         namei_flags = flags;
 820         if ((namei_flags+1) & O_ACCMODE)
 821                 namei_flags++;
 822         if (namei_flags & O_TRUNC)
 823                 namei_flags |= 2;
 824
 825         error = -ENFILE;
 826         f = get_empty_filp();
 827         if (f == NULL)
 828                 return ERR_PTR(error);
 829
 830         error = open_namei(filename, namei_flags, mode, &nd);
 831         if (!error)
 832                 return __dentry_open(nd.dentry, nd.mnt, flags, f);
 833
 834         put_filp(f);
 835         return ERR_PTR(error);
 836 }
 837 EXPORT_SYMBOL(filp_open);
 838
 839 struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags)
 840 {
 841         int error;
 842         struct file *f;
 843
 844         error = -ENFILE;
 845         f = get_empty_filp();
 846         if (f == NULL)
 847                 return ERR_PTR(error);
 848
 849         return __dentry_open(dentry, mnt, flags, f);
 850 }
 851 EXPORT_SYMBOL(dentry_open);
 852
 853 /*
 854  * Find an empty file descriptor entry, and mark it busy.
 855  */
 856 int get_unused_fd(void)
 857 {
 858         struct files_struct * files = current->files;
 859         int fd, error;
 860         struct fdtable *fdt;
 861
 862         error = -EMFILE;
 863         spin_lock(&files->file_lock);
 864
 865 repeat:
 866         fdt = files_fdtable(files);
 867         fd = find_next_zero_bit(fdt->open_fds->fds_bits,
 868                                 fdt->max_fdset,
 869                                 fdt->next_fd);
 870
 871         /*
 872          * N.B. For clone tasks sharing a files structure, this test
 873          * will limit the total number of files that can be opened.
 874          */
 875         if (fd >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur)
 876                 goto out;
 877
 878         /* Do we need to expand the fd array or fd set?  */
 879         error = expand_files(files, fd);
 880         if (error < 0)
 881                 goto out;
 882
 883         if (error) {
 884                 /*
 885                  * If we needed to expand the fs array we
 886                  * might have blocked - try again.
 887                  */
 888                 error = -EMFILE;
 889                 goto repeat;
 890         }
 891
 892         FD_SET(fd, fdt->open_fds);
 893         FD_CLR(fd, fdt->close_on_exec);
 894         fdt->next_fd = fd + 1;
 895 #if 1
 896         /* Sanity check */
 897         if (fdt->fd[fd] != NULL) {
 898                 printk(KERN_WARNING "get_unused_fd: slot %d not NULL!\n", fd);
 899                 fdt->fd[fd] = NULL;
 900         }
 901 #endif
 902         error = fd;
 903
 904 out:
 905         spin_unlock(&files->file_lock);
 906         return error;
 907 }
 908
 909 EXPORT_SYMBOL(get_unused_fd);
 910
 911 static inline void __put_unused_fd(struct files_struct *files, unsigned int fd)
 912 {
 913         struct fdtable *fdt = files_fdtable(files);
 914         __FD_CLR(fd, fdt->open_fds);
 915         if (fd < fdt->next_fd)
 916                 fdt->next_fd = fd;
 917 }
 918
 919 void fastcall put_unused_fd(unsigned int fd)
 920 {
 921         struct files_struct *files = current->files;
 922         spin_lock(&files->file_lock);
 923         __put_unused_fd(files, fd);
 924         spin_unlock(&files->file_lock);
 925 }
 926
 927 EXPORT_SYMBOL(put_unused_fd);
 928
 929 /*
 930  * Install a file pointer in the fd array.
 931  *
 932  * The VFS is full of places where we drop the files lock between
 933  * setting the open_fds bitmap and installing the file in the file
 934  * array.  At any such point, we are vulnerable to a dup2() race
 935  * installing a file in the array before us.  We need to detect this and
 936  * fput() the struct file we are about to overwrite in this case.
 937  *
 938  * It should never happen - if we allow dup2() do it, _really_ bad things
 939  * will follow.
 940  */
 941
 942 void fastcall fd_install(unsigned int fd, struct file * file)
 943 {
 944         struct files_struct *files = current->files;
 945         struct fdtable *fdt;
 946         spin_lock(&files->file_lock);
 947         fdt = files_fdtable(files);
 948         BUG_ON(fdt->fd[fd] != NULL);
 949         rcu_assign_pointer(fdt->fd[fd], file);
 950         spin_unlock(&files->file_lock);
 951 }
 952
 953 EXPORT_SYMBOL(fd_install);
 954
 955 long do_sys_open(const char __user *filename, int flags, int mode)
 956 {
 957         char *tmp = getname(filename);
 958         int fd = PTR_ERR(tmp);
 959
 960         if (!IS_ERR(tmp)) {
 961                 fd = get_unused_fd();
 962                 if (fd >= 0) {
 963                         struct file *f = filp_open(tmp, flags, mode);
 964                         if (IS_ERR(f)) {
 965                                 put_unused_fd(fd);
 966                                 fd = PTR_ERR(f);
 967                         } else {
 968                                 fsnotify_open(f->f_dentry);
 969                                 fd_install(fd, f);
 970                         }
 971                 }
 972                 putname(tmp);
 973         }
 974         return fd;
 975 }
 976
 977 asmlinkage long sys_open(const char __user *filename, int flags, int mode)
 978 {
 979         if (force_o_largefile())
 980                 flags |= O_LARGEFILE;
 981
 982         return do_sys_open(filename, flags, mode);
 983 }
 984 EXPORT_SYMBOL_GPL(sys_open);
 985
 986 #ifndef __alpha__
 987
 988 /*
 989  * For backward compatibility?  Maybe this should be moved
 990  * into arch/i386 instead?
 991  */
 992 asmlinkage long sys_creat(const char __user * pathname, int mode)
 993 {
 994         return sys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode);
 995 }
 996
 997 #endif
 998
 999 /*
1000  * "id" is the POSIX thread ID. We use the
1001  * files pointer for this..
1002  */
1003 int filp_close(struct file *filp, fl_owner_t id)
1004 {
1005         int retval = 0;
1006
1007         if (!file_count(filp)) {
1008                 printk(KERN_ERR "VFS: Close: file count is 0\n");
1009                 return 0;
1010         }
1011
1012         if (filp->f_op && filp->f_op->flush)
1013                 retval = filp->f_op->flush(filp);
1014
1015         dnotify_flush(filp, id);
1016         locks_remove_posix(filp, id);
1017         fput(filp);
1018         return retval;
1019 }
1020
1021 EXPORT_SYMBOL(filp_close);
1022
1023 /*
1024  * Careful here! We test whether the file pointer is NULL before
1025  * releasing the fd. This ensures that one clone task can't release
1026  * an fd while another clone is opening it.
1027  */
1028 asmlinkage long sys_close(unsigned int fd)
1029 {
1030         struct file * filp;
1031         struct files_struct *files = current->files;
1032         struct fdtable *fdt;
1033
1034         spin_lock(&files->file_lock);
1035         fdt = files_fdtable(files);
1036         if (fd >= fdt->max_fds)
1037                 goto out_unlock;
1038         filp = fdt->fd[fd];
1039         if (!filp)
1040                 goto out_unlock;
1041         rcu_assign_pointer(fdt->fd[fd], NULL);
1042         FD_CLR(fd, fdt->close_on_exec);
1043         __put_unused_fd(files, fd);
1044         spin_unlock(&files->file_lock);
1045         return filp_close(filp, files);
1046
1047 out_unlock:
1048         spin_unlock(&files->file_lock);
1049         return -EBADF;
1050 }
1051
1052 EXPORT_SYMBOL(sys_close);
1053
1054 /*
1055  * This routine simulates a hangup on the tty, to arrange that users
1056  * are given clean terminals at login time.
1057  */
1058 asmlinkage long sys_vhangup(void)
1059 {
1060         if (capable(CAP_SYS_TTY_CONFIG)) {
1061                 tty_vhangup(current->signal->tty);
1062                 return 0;
1063         }
1064         return -EPERM;
1065 }
1066
1067 /*
1068  * Called when an inode is about to be open.
1069  * We use this to disallow opening large files on 32bit systems if
1070  * the caller didn't specify O_LARGEFILE.  On 64bit systems we force
1071  * on this flag in sys_open.
1072  */
1073 int generic_file_open(struct inode * inode, struct file * filp)
1074 {
1075         if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
1076                 return -EFBIG;
1077         return 0;
1078 }
1079
1080 EXPORT_SYMBOL(generic_file_open);
1081
1082 /*
1083  * This is used by subsystems that don't want seekable
1084  * file descriptors
1085  */
1086 int nonseekable_open(struct inode *inode, struct file *filp)
1087 {
1088         filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
1089         return 0;
1090 }
1091
1092 EXPORT_SYMBOL(nonseekable_open);