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/capability.h>
  20 #include <linux/security.h>
  21 #include <linux/mount.h>
  22 #include <linux/vfs.h>
  23 #include <linux/fcntl.h>
  24 #include <asm/uaccess.h>
  25 #include <linux/fs.h>
  26 #include <linux/personality.h>
  27 #include <linux/pagemap.h>
  28 #include <linux/syscalls.h>
  29 #include <linux/rcupdate.h>
  30 #include <linux/audit.h>
  31
  32 #include <asm/unistd.h>
  33
  34 int vfs_statfs(struct dentry *dentry, struct kstatfs *buf)
  35 {
  36         int retval = -ENODEV;
  37
  38         if (dentry) {
  39                 retval = -ENOSYS;
  40                 if (dentry->d_sb->s_op->statfs) {
  41                         memset(buf, 0, sizeof(*buf));
  42                         retval = security_sb_statfs(dentry);
  43                         if (retval)
  44                                 return retval;
  45                         retval = dentry->d_sb->s_op->statfs(dentry, buf);
  46                         if (retval == 0 && buf->f_frsize == 0)
  47                                 buf->f_frsize = buf->f_bsize;
  48                 }
  49         }
  50         return retval;
  51 }
  52
  53 EXPORT_SYMBOL(vfs_statfs);
  54
  55 static int vfs_statfs_native(struct dentry *dentry, struct statfs *buf)
  56 {
  57         struct kstatfs st;
  58         int retval;
  59
  60         retval = vfs_statfs(dentry, &st);
  61         if (retval)
  62                 return retval;
  63
  64         if (sizeof(*buf) == sizeof(st))
  65                 memcpy(buf, &st, sizeof(st));
  66         else {
  67                 if (sizeof buf->f_blocks == 4) {
  68                         if ((st.f_blocks | st.f_bfree | st.f_bavail) &
  69                             0xffffffff00000000ULL)
  70                                 return -EOVERFLOW;
  71                         /*
  72                          * f_files and f_ffree may be -1; it's okay to stuff
  73                          * that into 32 bits
  74                          */
  75                         if (st.f_files != -1 &&
  76                             (st.f_files & 0xffffffff00000000ULL))
  77                                 return -EOVERFLOW;
  78                         if (st.f_ffree != -1 &&
  79                             (st.f_ffree & 0xffffffff00000000ULL))
  80                                 return -EOVERFLOW;
  81                 }
  82
  83                 buf->f_type = st.f_type;
  84                 buf->f_bsize = st.f_bsize;
  85                 buf->f_blocks = st.f_blocks;
  86                 buf->f_bfree = st.f_bfree;
  87                 buf->f_bavail = st.f_bavail;
  88                 buf->f_files = st.f_files;
  89                 buf->f_ffree = st.f_ffree;
  90                 buf->f_fsid = st.f_fsid;
  91                 buf->f_namelen = st.f_namelen;
  92                 buf->f_frsize = st.f_frsize;
  93                 memset(buf->f_spare, 0, sizeof(buf->f_spare));
  94         }
  95         return 0;
  96 }
  97
  98 static int vfs_statfs64(struct dentry *dentry, struct statfs64 *buf)
  99 {
 100         struct kstatfs st;
 101         int retval;
 102
 103         retval = vfs_statfs(dentry, &st);
 104         if (retval)
 105                 return retval;
 106
 107         if (sizeof(*buf) == sizeof(st))
 108                 memcpy(buf, &st, sizeof(st));
 109         else {
 110                 buf->f_type = st.f_type;
 111                 buf->f_bsize = st.f_bsize;
 112                 buf->f_blocks = st.f_blocks;
 113                 buf->f_bfree = st.f_bfree;
 114                 buf->f_bavail = st.f_bavail;
 115                 buf->f_files = st.f_files;
 116                 buf->f_ffree = st.f_ffree;
 117                 buf->f_fsid = st.f_fsid;
 118                 buf->f_namelen = st.f_namelen;
 119                 buf->f_frsize = st.f_frsize;
 120                 memset(buf->f_spare, 0, sizeof(buf->f_spare));
 121         }
 122         return 0;
 123 }
 124
 125 asmlinkage long sys_statfs(const char __user * path, struct statfs __user * buf)
 126 {
 127         struct nameidata nd;
 128         int error;
 129
 130         error = user_path_walk(path, &nd);
 131         if (!error) {
 132                 struct statfs tmp;
 133                 error = vfs_statfs_native(nd.dentry, &tmp);
 134                 if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
 135                         error = -EFAULT;
 136                 path_release(&nd);
 137         }
 138         return error;
 139 }
 140
 141
 142 asmlinkage long sys_statfs64(const char __user *path, size_t sz, struct statfs64 __user *buf)
 143 {
 144         struct nameidata nd;
 145         long error;
 146
 147         if (sz != sizeof(*buf))
 148                 return -EINVAL;
 149         error = user_path_walk(path, &nd);
 150         if (!error) {
 151                 struct statfs64 tmp;
 152                 error = vfs_statfs64(nd.dentry, &tmp);
 153                 if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
 154                         error = -EFAULT;
 155                 path_release(&nd);
 156         }
 157         return error;
 158 }
 159
 160
 161 asmlinkage long sys_fstatfs(unsigned int fd, struct statfs __user * buf)
 162 {
 163         struct file * file;
 164         struct statfs tmp;
 165         int error;
 166
 167         error = -EBADF;
 168         file = fget(fd);
 169         if (!file)
 170                 goto out;
 171         error = vfs_statfs_native(file->f_dentry, &tmp);
 172         if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
 173                 error = -EFAULT;
 174         fput(file);
 175 out:
 176         return error;
 177 }
 178
 179 asmlinkage long sys_fstatfs64(unsigned int fd, size_t sz, struct statfs64 __user *buf)
 180 {
 181         struct file * file;
 182         struct statfs64 tmp;
 183         int error;
 184
 185         if (sz != sizeof(*buf))
 186                 return -EINVAL;
 187
 188         error = -EBADF;
 189         file = fget(fd);
 190         if (!file)
 191                 goto out;
 192         error = vfs_statfs64(file->f_dentry, &tmp);
 193         if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
 194                 error = -EFAULT;
 195         fput(file);
 196 out:
 197         return error;
 198 }
 199
 200 int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
 201         struct file *filp)
 202 {
 203         int err;
 204         struct iattr newattrs;
 205
 206         /* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
 207         if (length < 0)
 208                 return -EINVAL;
 209
 210         newattrs.ia_size = length;
 211         newattrs.ia_valid = ATTR_SIZE | time_attrs;
 212         if (filp) {
 213                 newattrs.ia_file = filp;
 214                 newattrs.ia_valid |= ATTR_FILE;
 215         }
 216
 217         mutex_lock(&dentry->d_inode->i_mutex);
 218         err = notify_change(dentry, &newattrs);
 219         mutex_unlock(&dentry->d_inode->i_mutex);
 220         return err;
 221 }
 222
 223 static long do_sys_truncate(const char __user * path, loff_t length)
 224 {
 225         struct nameidata nd;
 226         struct inode * inode;
 227         int error;
 228
 229         error = -EINVAL;
 230         if (length < 0) /* sorry, but loff_t says... */
 231                 goto out;
 232
 233         error = user_path_walk(path, &nd);
 234         if (error)
 235                 goto out;
 236         inode = nd.dentry->d_inode;
 237
 238         /* For directories it's -EISDIR, for other non-regulars - -EINVAL */
 239         error = -EISDIR;
 240         if (S_ISDIR(inode->i_mode))
 241                 goto dput_and_out;
 242
 243         error = -EINVAL;
 244         if (!S_ISREG(inode->i_mode))
 245                 goto dput_and_out;
 246
 247         error = vfs_permission(&nd, MAY_WRITE);
 248         if (error)
 249                 goto dput_and_out;
 250
 251         error = -EROFS;
 252         if (IS_RDONLY(inode))
 253                 goto dput_and_out;
 254
 255         error = -EPERM;
 256         if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
 257                 goto dput_and_out;
 258
 259         /*
 260          * Make sure that there are no leases.
 261          */
 262         error = break_lease(inode, FMODE_WRITE);
 263         if (error)
 264                 goto dput_and_out;
 265
 266         error = get_write_access(inode);
 267         if (error)
 268                 goto dput_and_out;
 269
 270         error = locks_verify_truncate(inode, NULL, length);
 271         if (!error) {
 272                 DQUOT_INIT(inode);
 273                 error = do_truncate(nd.dentry, length, 0, NULL);
 274         }
 275         put_write_access(inode);
 276
 277 dput_and_out:
 278         path_release(&nd);
 279 out:
 280         return error;
 281 }
 282
 283 asmlinkage long sys_truncate(const char __user * path, unsigned long length)
 284 {
 285         /* on 32-bit boxen it will cut the range 2^31--2^32-1 off */
 286         return do_sys_truncate(path, (long)length);
 287 }
 288
 289 static long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
 290 {
 291         struct inode * inode;
 292         struct dentry *dentry;
 293         struct file * file;
 294         int error;
 295
 296         error = -EINVAL;
 297         if (length < 0)
 298                 goto out;
 299         error = -EBADF;
 300         file = fget(fd);
 301         if (!file)
 302                 goto out;
 303
 304         /* explicitly opened as large or we are on 64-bit box */
 305         if (file->f_flags & O_LARGEFILE)
 306                 small = 0;
 307
 308         dentry = file->f_dentry;
 309         inode = dentry->d_inode;
 310         error = -EINVAL;
 311         if (!S_ISREG(inode->i_mode) || !(file->f_mode & FMODE_WRITE))
 312                 goto out_putf;
 313
 314         error = -EINVAL;
 315         /* Cannot ftruncate over 2^31 bytes without large file support */
 316         if (small && length > MAX_NON_LFS)
 317                 goto out_putf;
 318
 319         error = -EPERM;
 320         if (IS_APPEND(inode))
 321                 goto out_putf;
 322
 323         error = locks_verify_truncate(inode, file, length);
 324         if (!error)
 325                 error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, file);
 326 out_putf:
 327         fput(file);
 328 out:
 329         return error;
 330 }
 331
 332 asmlinkage long sys_ftruncate(unsigned int fd, unsigned long length)
 333 {
 334         long ret = do_sys_ftruncate(fd, length, 1);
 335         /* avoid REGPARM breakage on x86: */
 336         prevent_tail_call(ret);
 337         return ret;
 338 }
 339
 340 /* LFS versions of truncate are only needed on 32 bit machines */
 341 #if BITS_PER_LONG == 32
 342 asmlinkage long sys_truncate64(const char __user * path, loff_t length)
 343 {
 344         return do_sys_truncate(path, length);
 345 }
 346
 347 asmlinkage long sys_ftruncate64(unsigned int fd, loff_t length)
 348 {
 349         long ret = do_sys_ftruncate(fd, length, 0);
 350         /* avoid REGPARM breakage on x86: */
 351         prevent_tail_call(ret);
 352         return ret;
 353 }
 354 #endif
 355
 356 #ifdef __ARCH_WANT_SYS_UTIME
 357
 358 /*
 359  * sys_utime() can be implemented in user-level using sys_utimes().
 360  * Is this for backwards compatibility?  If so, why not move it
 361  * into the appropriate arch directory (for those architectures that
 362  * need it).
 363  */
 364
 365 /* If times==NULL, set access and modification to current time,
 366  * must be owner or have write permission.
 367  * Else, update from *times, must be owner or super user.
 368  */
 369 asmlinkage long sys_utime(char __user * filename, struct utimbuf __user * times)
 370 {
 371         int error;
 372         struct nameidata nd;
 373         struct inode * inode;
 374         struct iattr newattrs;
 375
 376         error = user_path_walk(filename, &nd);
 377         if (error)
 378                 goto out;
 379         inode = nd.dentry->d_inode;
 380
 381         error = -EROFS;
 382         if (IS_RDONLY(inode))
 383                 goto dput_and_out;
 384
 385         /* Don't worry, the checks are done in inode_change_ok() */
 386         newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
 387         if (times) {
 388                 error = -EPERM;
 389                 if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
 390                         goto dput_and_out;
 391
 392                 error = get_user(newattrs.ia_atime.tv_sec, &times->actime);
 393                 newattrs.ia_atime.tv_nsec = 0;
 394                 if (!error)
 395                         error = get_user(newattrs.ia_mtime.tv_sec, &times->modtime);
 396                 newattrs.ia_mtime.tv_nsec = 0;
 397                 if (error)
 398                         goto dput_and_out;
 399
 400                 newattrs.ia_valid |= ATTR_ATIME_SET | ATTR_MTIME_SET;
 401         } else {
 402                 error = -EACCES;
 403                 if (IS_IMMUTABLE(inode))
 404                         goto dput_and_out;
 405
 406                 if (current->fsuid != inode->i_uid &&
 407                     (error = vfs_permission(&nd, MAY_WRITE)) != 0)
 408                         goto dput_and_out;
 409         }
 410         mutex_lock(&inode->i_mutex);
 411         error = notify_change(nd.dentry, &newattrs);
 412         mutex_unlock(&inode->i_mutex);
 413 dput_and_out:
 414         path_release(&nd);
 415 out:
 416         return error;
 417 }
 418
 419 #endif
 420
 421 /* If times==NULL, set access and modification to current time,
 422  * must be owner or have write permission.
 423  * Else, update from *times, must be owner or super user.
 424  */
 425 long do_utimes(int dfd, char __user *filename, struct timeval *times)
 426 {
 427         int error;
 428         struct nameidata nd;
 429         struct inode * inode;
 430         struct iattr newattrs;
 431
 432         error = __user_walk_fd(dfd, filename, LOOKUP_FOLLOW, &nd);
 433
 434         if (error)
 435                 goto out;
 436         inode = nd.dentry->d_inode;
 437
 438         error = -EROFS;
 439         if (IS_RDONLY(inode))
 440                 goto dput_and_out;
 441
 442         /* Don't worry, the checks are done in inode_change_ok() */
 443         newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
 444         if (times) {
 445                 error = -EPERM;
 446                 if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
 447                         goto dput_and_out;
 448
 449                 newattrs.ia_atime.tv_sec = times[0].tv_sec;
 450                 newattrs.ia_atime.tv_nsec = times[0].tv_usec * 1000;
 451                 newattrs.ia_mtime.tv_sec = times[1].tv_sec;
 452                 newattrs.ia_mtime.tv_nsec = times[1].tv_usec * 1000;
 453                 newattrs.ia_valid |= ATTR_ATIME_SET | ATTR_MTIME_SET;
 454         } else {
 455                 error = -EACCES;
 456                 if (IS_IMMUTABLE(inode))
 457                         goto dput_and_out;
 458
 459                 if (current->fsuid != inode->i_uid &&
 460                     (error = vfs_permission(&nd, MAY_WRITE)) != 0)
 461                         goto dput_and_out;
 462         }
 463         mutex_lock(&inode->i_mutex);
 464         error = notify_change(nd.dentry, &newattrs);
 465         mutex_unlock(&inode->i_mutex);
 466 dput_and_out:
 467         path_release(&nd);
 468 out:
 469         return error;
 470 }
 471
 472 asmlinkage long sys_futimesat(int dfd, char __user *filename, struct timeval __user *utimes)
 473 {
 474         struct timeval times[2];
 475
 476         if (utimes && copy_from_user(&times, utimes, sizeof(times)))
 477                 return -EFAULT;
 478         return do_utimes(dfd, filename, utimes ? times : NULL);
 479 }
 480
 481 asmlinkage long sys_utimes(char __user *filename, struct timeval __user *utimes)
 482 {
 483         return sys_futimesat(AT_FDCWD, filename, utimes);
 484 }
 485
 486
 487 /*
 488  * access() needs to use the real uid/gid, not the effective uid/gid.
 489  * We do this by temporarily clearing all FS-related capabilities and
 490  * switching the fsuid/fsgid around to the real ones.
 491  */
 492 asmlinkage long sys_faccessat(int dfd, const char __user *filename, int mode)
 493 {
 494         struct nameidata nd;
 495         int old_fsuid, old_fsgid;
 496         kernel_cap_t old_cap;
 497         int res;
 498
 499         if (mode & ~S_IRWXO)    /* where's F_OK, X_OK, W_OK, R_OK? */
 500                 return -EINVAL;
 501
 502         old_fsuid = current->fsuid;
 503         old_fsgid = current->fsgid;
 504         old_cap = current->cap_effective;
 505
 506         current->fsuid = current->uid;
 507         current->fsgid = current->gid;
 508
 509         /*
 510          * Clear the capabilities if we switch to a non-root user
 511          *
 512          * FIXME: There is a race here against sys_capset.  The
 513          * capabilities can change yet we will restore the old
 514          * value below.  We should hold task_capabilities_lock,
 515          * but we cannot because user_path_walk can sleep.
 516          */
 517         if (current->uid)
 518                 cap_clear(current->cap_effective);
 519         else
 520                 current->cap_effective = current->cap_permitted;
 521
 522         res = __user_walk_fd(dfd, filename, LOOKUP_FOLLOW|LOOKUP_ACCESS, &nd);
 523         if (!res) {
 524                 res = vfs_permission(&nd, mode);
 525                 /* SuS v2 requires we report a read only fs too */
 526                 if(!res && (mode & S_IWOTH) && IS_RDONLY(nd.dentry->d_inode)
 527                    && !special_file(nd.dentry->d_inode->i_mode))
 528                         res = -EROFS;
 529                 path_release(&nd);
 530         }
 531
 532         current->fsuid = old_fsuid;
 533         current->fsgid = old_fsgid;
 534         current->cap_effective = old_cap;
 535
 536         return res;
 537 }
 538
 539 asmlinkage long sys_access(const char __user *filename, int mode)
 540 {
 541         return sys_faccessat(AT_FDCWD, filename, mode);
 542 }
 543
 544 asmlinkage long sys_chdir(const char __user * filename)
 545 {
 546         struct nameidata nd;
 547         int error;
 548
 549         error = __user_walk(filename, LOOKUP_FOLLOW|LOOKUP_DIRECTORY, &nd);
 550         if (error)
 551                 goto out;
 552
 553         error = vfs_permission(&nd, MAY_EXEC);
 554         if (error)
 555                 goto dput_and_out;
 556
 557         set_fs_pwd(current->fs, nd.mnt, nd.dentry);
 558
 559 dput_and_out:
 560         path_release(&nd);
 561 out:
 562         return error;
 563 }
 564
 565 asmlinkage long sys_fchdir(unsigned int fd)
 566 {
 567         struct file *file;
 568         struct dentry *dentry;
 569         struct inode *inode;
 570         struct vfsmount *mnt;
 571         int error;
 572
 573         error = -EBADF;
 574         file = fget(fd);
 575         if (!file)
 576                 goto out;
 577
 578         dentry = file->f_dentry;
 579         mnt = file->f_vfsmnt;
 580         inode = dentry->d_inode;
 581
 582         error = -ENOTDIR;
 583         if (!S_ISDIR(inode->i_mode))
 584                 goto out_putf;
 585
 586         error = file_permission(file, MAY_EXEC);
 587         if (!error)
 588                 set_fs_pwd(current->fs, mnt, dentry);
 589 out_putf:
 590         fput(file);
 591 out:
 592         return error;
 593 }
 594
 595 asmlinkage long sys_chroot(const char __user * filename)
 596 {
 597         struct nameidata nd;
 598         int error;
 599
 600         error = __user_walk(filename, LOOKUP_FOLLOW | LOOKUP_DIRECTORY | LOOKUP_NOALT, &nd);
 601         if (error)
 602                 goto out;
 603
 604         error = vfs_permission(&nd, MAY_EXEC);
 605         if (error)
 606                 goto dput_and_out;
 607
 608         error = -EPERM;
 609         if (!capable(CAP_SYS_CHROOT))
 610                 goto dput_and_out;
 611
 612         set_fs_root(current->fs, nd.mnt, nd.dentry);
 613         set_fs_altroot();
 614         error = 0;
 615 dput_and_out:
 616         path_release(&nd);
 617 out:
 618         return error;
 619 }
 620
 621 asmlinkage long sys_fchmod(unsigned int fd, mode_t mode)
 622 {
 623         struct inode * inode;
 624         struct dentry * dentry;
 625         struct file * file;
 626         int err = -EBADF;
 627         struct iattr newattrs;
 628
 629         file = fget(fd);
 630         if (!file)
 631                 goto out;
 632
 633         dentry = file->f_dentry;
 634         inode = dentry->d_inode;
 635
 636         audit_inode(NULL, inode);
 637
 638         err = -EROFS;
 639         if (IS_RDONLY(inode))
 640                 goto out_putf;
 641         err = -EPERM;
 642         if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
 643                 goto out_putf;
 644         mutex_lock(&inode->i_mutex);
 645         if (mode == (mode_t) -1)
 646                 mode = inode->i_mode;
 647         newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
 648         newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
 649         err = notify_change(dentry, &newattrs);
 650         mutex_unlock(&inode->i_mutex);
 651
 652 out_putf:
 653         fput(file);
 654 out:
 655         return err;
 656 }
 657
 658 asmlinkage long sys_fchmodat(int dfd, const char __user *filename,
 659                              mode_t mode)
 660 {
 661         struct nameidata nd;
 662         struct inode * inode;
 663         int error;
 664         struct iattr newattrs;
 665
 666         error = __user_walk_fd(dfd, filename, LOOKUP_FOLLOW, &nd);
 667         if (error)
 668                 goto out;
 669         inode = nd.dentry->d_inode;
 670
 671         error = -EROFS;
 672         if (IS_RDONLY(inode))
 673                 goto dput_and_out;
 674
 675         error = -EPERM;
 676         if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
 677                 goto dput_and_out;
 678
 679         mutex_lock(&inode->i_mutex);
 680         if (mode == (mode_t) -1)
 681                 mode = inode->i_mode;
 682         newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
 683         newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
 684         error = notify_change(nd.dentry, &newattrs);
 685         mutex_unlock(&inode->i_mutex);
 686
 687 dput_and_out:
 688         path_release(&nd);
 689 out:
 690         return error;
 691 }
 692
 693 asmlinkage long sys_chmod(const char __user *filename, mode_t mode)
 694 {
 695         return sys_fchmodat(AT_FDCWD, filename, mode);
 696 }
 697
 698 static int chown_common(struct dentry * dentry, uid_t user, gid_t group)
 699 {
 700         struct inode * inode;
 701         int error;
 702         struct iattr newattrs;
 703
 704         error = -ENOENT;
 705         if (!(inode = dentry->d_inode)) {
 706                 printk(KERN_ERR "chown_common: NULL inode\n");
 707                 goto out;
 708         }
 709         error = -EROFS;
 710         if (IS_RDONLY(inode))
 711                 goto out;
 712         error = -EPERM;
 713         if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
 714                 goto out;
 715         newattrs.ia_valid =  ATTR_CTIME;
 716         if (user != (uid_t) -1) {
 717                 newattrs.ia_valid |= ATTR_UID;
 718                 newattrs.ia_uid = user;
 719         }
 720         if (group != (gid_t) -1) {
 721                 newattrs.ia_valid |= ATTR_GID;
 722                 newattrs.ia_gid = group;
 723         }
 724         if (!S_ISDIR(inode->i_mode))
 725                 newattrs.ia_valid |= ATTR_KILL_SUID|ATTR_KILL_SGID;
 726         mutex_lock(&inode->i_mutex);
 727         error = notify_change(dentry, &newattrs);
 728         mutex_unlock(&inode->i_mutex);
 729 out:
 730         return error;
 731 }
 732
 733 asmlinkage long sys_chown(const char __user * filename, uid_t user, gid_t group)
 734 {
 735         struct nameidata nd;
 736         int error;
 737
 738         error = user_path_walk(filename, &nd);
 739         if (!error) {
 740                 error = chown_common(nd.dentry, user, group);
 741                 path_release(&nd);
 742         }
 743         return error;
 744 }
 745
 746 asmlinkage long sys_fchownat(int dfd, const char __user *filename, uid_t user,
 747                              gid_t group, int flag)
 748 {
 749         struct nameidata nd;
 750         int error = -EINVAL;
 751         int follow;
 752
 753         if ((flag & ~AT_SYMLINK_NOFOLLOW) != 0)
 754                 goto out;
 755
 756         follow = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
 757         error = __user_walk_fd(dfd, filename, follow, &nd);
 758         if (!error) {
 759                 error = chown_common(nd.dentry, user, group);
 760                 path_release(&nd);
 761         }
 762 out:
 763         return error;
 764 }
 765
 766 asmlinkage long sys_lchown(const char __user * filename, uid_t user, gid_t group)
 767 {
 768         struct nameidata nd;
 769         int error;
 770
 771         error = user_path_walk_link(filename, &nd);
 772         if (!error) {
 773                 error = chown_common(nd.dentry, user, group);
 774                 path_release(&nd);
 775         }
 776         return error;
 777 }
 778
 779
 780 asmlinkage long sys_fchown(unsigned int fd, uid_t user, gid_t group)
 781 {
 782         struct file * file;
 783         int error = -EBADF;
 784
 785         file = fget(fd);
 786         if (file) {
 787                 struct dentry * dentry;
 788                 dentry = file->f_dentry;
 789                 audit_inode(NULL, dentry->d_inode);
 790                 error = chown_common(dentry, user, group);
 791                 fput(file);
 792         }
 793         return error;
 794 }
 795
 796 static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
 797                                         int flags, struct file *f,
 798                                         int (*open)(struct inode *, struct file *))
 799 {
 800         struct inode *inode;
 801         int error;
 802
 803         f->f_flags = flags;
 804         f->f_mode = ((flags+1) & O_ACCMODE) | FMODE_LSEEK |
 805                                 FMODE_PREAD | FMODE_PWRITE;
 806         inode = dentry->d_inode;
 807         if (f->f_mode & FMODE_WRITE) {
 808                 error = get_write_access(inode);
 809                 if (error)
 810                         goto cleanup_file;
 811         }
 812
 813         f->f_mapping = inode->i_mapping;
 814         f->f_dentry = dentry;
 815         f->f_vfsmnt = mnt;
 816         f->f_pos = 0;
 817         f->f_op = fops_get(inode->i_fop);
 818         file_move(f, &inode->i_sb->s_files);
 819
 820         if (!open && f->f_op)
 821                 open = f->f_op->open;
 822         if (open) {
 823                 error = open(inode, f);
 824                 if (error)
 825                         goto cleanup_all;
 826         }
 827
 828         f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
 829
 830         file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
 831
 832         /* NB: we're sure to have correct a_ops only after f_op->open */
 833         if (f->f_flags & O_DIRECT) {
 834                 if (!f->f_mapping->a_ops ||
 835                     ((!f->f_mapping->a_ops->direct_IO) &&
 836                     (!f->f_mapping->a_ops->get_xip_page))) {
 837                         fput(f);
 838                         f = ERR_PTR(-EINVAL);
 839                 }
 840         }
 841
 842         return f;
 843
 844 cleanup_all:
 845         fops_put(f->f_op);
 846         if (f->f_mode & FMODE_WRITE)
 847                 put_write_access(inode);
 848         file_kill(f);
 849         f->f_dentry = NULL;
 850         f->f_vfsmnt = NULL;
 851 cleanup_file:
 852         put_filp(f);
 853         dput(dentry);
 854         mntput(mnt);
 855         return ERR_PTR(error);
 856 }
 857
 858 /*
 859  * Note that while the flag value (low two bits) for sys_open means:
 860  *      00 - read-only
 861  *      01 - write-only
 862  *      10 - read-write
 863  *      11 - special
 864  * it is changed into
 865  *      00 - no permissions needed
 866  *      01 - read-permission
 867  *      10 - write-permission
 868  *      11 - read-write
 869  * for the internal routines (ie open_namei()/follow_link() etc). 00 is
 870  * used by symlinks.
 871  */
 872 static struct file *do_filp_open(int dfd, const char *filename, int flags,
 873                                  int mode)
 874 {
 875         int namei_flags, error;
 876         struct nameidata nd;
 877
 878         namei_flags = flags;
 879         if ((namei_flags+1) & O_ACCMODE)
 880                 namei_flags++;
 881
 882         error = open_namei(dfd, filename, namei_flags, mode, &nd);
 883         if (!error)
 884                 return nameidata_to_filp(&nd, flags);
 885
 886         return ERR_PTR(error);
 887 }
 888
 889 struct file *filp_open(const char *filename, int flags, int mode)
 890 {
 891         return do_filp_open(AT_FDCWD, filename, flags, mode);
 892 }
 893 EXPORT_SYMBOL(filp_open);
 894
 895 /**
 896  * lookup_instantiate_filp - instantiates the open intent filp
 897  * @nd: pointer to nameidata
 898  * @dentry: pointer to dentry
 899  * @open: open callback
 900  *
 901  * Helper for filesystems that want to use lookup open intents and pass back
 902  * a fully instantiated struct file to the caller.
 903  * This function is meant to be called from within a filesystem's
 904  * lookup method.
 905  * Beware of calling it for non-regular files! Those ->open methods might block
 906  * (e.g. in fifo_open), leaving you with parent locked (and in case of fifo,
 907  * leading to a deadlock, as nobody can open that fifo anymore, because
 908  * another process to open fifo will block on locked parent when doing lookup).
 909  * Note that in case of error, nd->intent.open.file is destroyed, but the
 910  * path information remains valid.
 911  * If the open callback is set to NULL, then the standard f_op->open()
 912  * filesystem callback is substituted.
 913  */
 914 struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry,
 915                 int (*open)(struct inode *, struct file *))
 916 {
 917         if (IS_ERR(nd->intent.open.file))
 918                 goto out;
 919         if (IS_ERR(dentry))
 920                 goto out_err;
 921         nd->intent.open.file = __dentry_open(dget(dentry), mntget(nd->mnt),
 922                                              nd->intent.open.flags - 1,
 923                                              nd->intent.open.file,
 924                                              open);
 925 out:
 926         return nd->intent.open.file;
 927 out_err:
 928         release_open_intent(nd);
 929         nd->intent.open.file = (struct file *)dentry;
 930         goto out;
 931 }
 932 EXPORT_SYMBOL_GPL(lookup_instantiate_filp);
 933
 934 /**
 935  * nameidata_to_filp - convert a nameidata to an open filp.
 936  * @nd: pointer to nameidata
 937  * @flags: open flags
 938  *
 939  * Note that this function destroys the original nameidata
 940  */
 941 struct file *nameidata_to_filp(struct nameidata *nd, int flags)
 942 {
 943         struct file *filp;
 944
 945         /* Pick up the filp from the open intent */
 946         filp = nd->intent.open.file;
 947         /* Has the filesystem initialised the file for us? */
 948         if (filp->f_dentry == NULL)
 949                 filp = __dentry_open(nd->dentry, nd->mnt, flags, filp, NULL);
 950         else
 951                 path_release(nd);
 952         return filp;
 953 }
 954
 955 /*
 956  * dentry_open() will have done dput(dentry) and mntput(mnt) if it returns an
 957  * error.
 958  */
 959 struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags)
 960 {
 961         int error;
 962         struct file *f;
 963
 964         error = -ENFILE;
 965         f = get_empty_filp();
 966         if (f == NULL) {
 967                 dput(dentry);
 968                 mntput(mnt);
 969                 return ERR_PTR(error);
 970         }
 971
 972         return __dentry_open(dentry, mnt, flags, f, NULL);
 973 }
 974 EXPORT_SYMBOL(dentry_open);
 975
 976 /*
 977  * Find an empty file descriptor entry, and mark it busy.
 978  */
 979 int get_unused_fd(void)
 980 {
 981         struct files_struct * files = current->files;
 982         int fd, error;
 983         struct fdtable *fdt;
 984
 985         error = -EMFILE;
 986         spin_lock(&files->file_lock);
 987
 988 repeat:
 989         fdt = files_fdtable(files);
 990         fd = find_next_zero_bit(fdt->open_fds->fds_bits,
 991                                 fdt->max_fdset,
 992                                 files->next_fd);
 993
 994         /*
 995          * N.B. For clone tasks sharing a files structure, this test
 996          * will limit the total number of files that can be opened.
 997          */
 998         if (fd >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur)
 999                 goto out;
1000
1001         /* Do we need to expand the fd array or fd set?  */
1002         error = expand_files(files, fd);
1003         if (error < 0)
1004                 goto out;
1005
1006         if (error) {
1007                 /*
1008                  * If we needed to expand the fs array we
1009                  * might have blocked - try again.
1010                  */
1011                 error = -EMFILE;
1012                 goto repeat;
1013         }
1014
1015         FD_SET(fd, fdt->open_fds);
1016         FD_CLR(fd, fdt->close_on_exec);
1017         files->next_fd = fd + 1;
1018 #if 1
1019         /* Sanity check */
1020         if (fdt->fd[fd] != NULL) {
1021                 printk(KERN_WARNING "get_unused_fd: slot %d not NULL!\n", fd);
1022                 fdt->fd[fd] = NULL;
1023         }
1024 #endif
1025         error = fd;
1026
1027 out:
1028         spin_unlock(&files->file_lock);
1029         return error;
1030 }
1031
1032 EXPORT_SYMBOL(get_unused_fd);
1033
1034 static void __put_unused_fd(struct files_struct *files, unsigned int fd)
1035 {
1036         struct fdtable *fdt = files_fdtable(files);
1037         __FD_CLR(fd, fdt->open_fds);
1038         if (fd < files->next_fd)
1039                 files->next_fd = fd;
1040 }
1041
1042 void fastcall put_unused_fd(unsigned int fd)
1043 {
1044         struct files_struct *files = current->files;
1045         spin_lock(&files->file_lock);
1046         __put_unused_fd(files, fd);
1047         spin_unlock(&files->file_lock);
1048 }
1049
1050 EXPORT_SYMBOL(put_unused_fd);
1051
1052 /*
1053  * Install a file pointer in the fd array.
1054  *
1055  * The VFS is full of places where we drop the files lock between
1056  * setting the open_fds bitmap and installing the file in the file
1057  * array.  At any such point, we are vulnerable to a dup2() race
1058  * installing a file in the array before us.  We need to detect this and
1059  * fput() the struct file we are about to overwrite in this case.
1060  *
1061  * It should never happen - if we allow dup2() do it, _really_ bad things
1062  * will follow.
1063  */
1064
1065 void fastcall fd_install(unsigned int fd, struct file * file)
1066 {
1067         struct files_struct *files = current->files;
1068         struct fdtable *fdt;
1069         spin_lock(&files->file_lock);
1070         fdt = files_fdtable(files);
1071         BUG_ON(fdt->fd[fd] != NULL);
1072         rcu_assign_pointer(fdt->fd[fd], file);
1073         spin_unlock(&files->file_lock);
1074 }
1075
1076 EXPORT_SYMBOL(fd_install);
1077
1078 long do_sys_open(int dfd, const char __user *filename, int flags, int mode)
1079 {
1080         char *tmp = getname(filename);
1081         int fd = PTR_ERR(tmp);
1082
1083         if (!IS_ERR(tmp)) {
1084                 fd = get_unused_fd();
1085                 if (fd >= 0) {
1086                         struct file *f = do_filp_open(dfd, tmp, flags, mode);
1087                         if (IS_ERR(f)) {
1088                                 put_unused_fd(fd);
1089                                 fd = PTR_ERR(f);
1090                         } else {
1091                                 fsnotify_open(f->f_dentry);
1092                                 fd_install(fd, f);
1093                         }
1094                 }
1095                 putname(tmp);
1096         }
1097         return fd;
1098 }
1099
1100 asmlinkage long sys_open(const char __user *filename, int flags, int mode)
1101 {
1102         long ret;
1103
1104         if (force_o_largefile())
1105                 flags |= O_LARGEFILE;
1106
1107         ret = do_sys_open(AT_FDCWD, filename, flags, mode);
1108         /* avoid REGPARM breakage on x86: */
1109         prevent_tail_call(ret);
1110         return ret;
1111 }
1112 EXPORT_SYMBOL_GPL(sys_open);
1113
1114 asmlinkage long sys_openat(int dfd, const char __user *filename, int flags,
1115                            int mode)
1116 {
1117         long ret;
1118
1119         if (force_o_largefile())
1120                 flags |= O_LARGEFILE;
1121
1122         ret = do_sys_open(dfd, filename, flags, mode);
1123         /* avoid REGPARM breakage on x86: */
1124         prevent_tail_call(ret);
1125         return ret;
1126 }
1127
1128 #ifndef __alpha__
1129
1130 /*
1131  * For backward compatibility?  Maybe this should be moved
1132  * into arch/i386 instead?
1133  */
1134 asmlinkage long sys_creat(const char __user * pathname, int mode)
1135 {
1136         return sys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode);
1137 }
1138
1139 #endif
1140
1141 /*
1142  * "id" is the POSIX thread ID. We use the
1143  * files pointer for this..
1144  */
1145 int filp_close(struct file *filp, fl_owner_t id)
1146 {
1147         int retval = 0;
1148
1149         if (!file_count(filp)) {
1150                 printk(KERN_ERR "VFS: Close: file count is 0\n");
1151                 return 0;
1152         }
1153
1154         if (filp->f_op && filp->f_op->flush)
1155                 retval = filp->f_op->flush(filp, id);
1156
1157         dnotify_flush(filp, id);
1158         locks_remove_posix(filp, id);
1159         fput(filp);
1160         return retval;
1161 }
1162
1163 EXPORT_SYMBOL(filp_close);
1164
1165 /*
1166  * Careful here! We test whether the file pointer is NULL before
1167  * releasing the fd. This ensures that one clone task can't release
1168  * an fd while another clone is opening it.
1169  */
1170 asmlinkage long sys_close(unsigned int fd)
1171 {
1172         struct file * filp;
1173         struct files_struct *files = current->files;
1174         struct fdtable *fdt;
1175
1176         spin_lock(&files->file_lock);
1177         fdt = files_fdtable(files);
1178         if (fd >= fdt->max_fds)
1179                 goto out_unlock;
1180         filp = fdt->fd[fd];
1181         if (!filp)
1182                 goto out_unlock;
1183         rcu_assign_pointer(fdt->fd[fd], NULL);
1184         FD_CLR(fd, fdt->close_on_exec);
1185         __put_unused_fd(files, fd);
1186         spin_unlock(&files->file_lock);
1187         return filp_close(filp, files);
1188
1189 out_unlock:
1190         spin_unlock(&files->file_lock);
1191         return -EBADF;
1192 }
1193
1194 EXPORT_SYMBOL(sys_close);
1195
1196 /*
1197  * This routine simulates a hangup on the tty, to arrange that users
1198  * are given clean terminals at login time.
1199  */
1200 asmlinkage long sys_vhangup(void)
1201 {
1202         if (capable(CAP_SYS_TTY_CONFIG)) {
1203                 tty_vhangup(current->signal->tty);
1204                 return 0;
1205         }
1206         return -EPERM;
1207 }
1208
1209 /*
1210  * Called when an inode is about to be open.
1211  * We use this to disallow opening large files on 32bit systems if
1212  * the caller didn't specify O_LARGEFILE.  On 64bit systems we force
1213  * on this flag in sys_open.
1214  */
1215 int generic_file_open(struct inode * inode, struct file * filp)
1216 {
1217         if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
1218                 return -EFBIG;
1219         return 0;
1220 }
1221
1222 EXPORT_SYMBOL(generic_file_open);
1223
1224 /*
1225  * This is used by subsystems that don't want seekable
1226  * file descriptors
1227  */
1228 int nonseekable_open(struct inode *inode, struct file *filp)
1229 {
1230         filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
1231         return 0;
1232 }
1233
1234 EXPORT_SYMBOL(nonseekable_open);