open.c 27.4 KB
Newer Older
Linus Torvalds's avatar
Linus Torvalds committed
1 2 3 4 5 6 7 8 9
/*
 *  linux/fs/open.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

#include <linux/string.h>
#include <linux/mm.h>
#include <linux/file.h>
Al Viro's avatar
Al Viro committed
10
#include <linux/fdtable.h>
Linus Torvalds's avatar
Linus Torvalds committed
11
#include <linux/quotaops.h>
Robert Love's avatar
Robert Love committed
12
#include <linux/fsnotify.h>
Linus Torvalds's avatar
Linus Torvalds committed
13 14 15 16 17
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/tty.h>
#include <linux/namei.h>
#include <linux/backing-dev.h>
18
#include <linux/capability.h>
19
#include <linux/securebits.h>
Linus Torvalds's avatar
Linus Torvalds committed
20 21 22
#include <linux/security.h>
#include <linux/mount.h>
#include <linux/vfs.h>
23
#include <linux/fcntl.h>
Linus Torvalds's avatar
Linus Torvalds committed
24 25
#include <asm/uaccess.h>
#include <linux/fs.h>
26
#include <linux/personality.h>
Linus Torvalds's avatar
Linus Torvalds committed
27 28
#include <linux/pagemap.h>
#include <linux/syscalls.h>
29
#include <linux/rcupdate.h>
30
#include <linux/audit.h>
31
#include <linux/falloc.h>
32
#include <linux/fs_struct.h>
Linus Torvalds's avatar
Linus Torvalds committed
33

34
int vfs_statfs(struct dentry *dentry, struct kstatfs *buf)
Linus Torvalds's avatar
Linus Torvalds committed
35 36 37
{
	int retval = -ENODEV;

38
	if (dentry) {
Linus Torvalds's avatar
Linus Torvalds committed
39
		retval = -ENOSYS;
40
		if (dentry->d_sb->s_op->statfs) {
Linus Torvalds's avatar
Linus Torvalds committed
41
			memset(buf, 0, sizeof(*buf));
42
			retval = security_sb_statfs(dentry);
Linus Torvalds's avatar
Linus Torvalds committed
43 44
			if (retval)
				return retval;
45
			retval = dentry->d_sb->s_op->statfs(dentry, buf);
Linus Torvalds's avatar
Linus Torvalds committed
46 47 48 49 50 51 52 53 54
			if (retval == 0 && buf->f_frsize == 0)
				buf->f_frsize = buf->f_bsize;
		}
	}
	return retval;
}

EXPORT_SYMBOL(vfs_statfs);

55
static int vfs_statfs_native(struct dentry *dentry, struct statfs *buf)
Linus Torvalds's avatar
Linus Torvalds committed
56 57 58 59
{
	struct kstatfs st;
	int retval;

60
	retval = vfs_statfs(dentry, &st);
Linus Torvalds's avatar
Linus Torvalds committed
61 62 63 64 65 66 67
	if (retval)
		return retval;

	if (sizeof(*buf) == sizeof(st))
		memcpy(buf, &st, sizeof(st));
	else {
		if (sizeof buf->f_blocks == 4) {
Jon Tollefson's avatar
Jon Tollefson committed
68 69
			if ((st.f_blocks | st.f_bfree | st.f_bavail |
			     st.f_bsize | st.f_frsize) &
Linus Torvalds's avatar
Linus Torvalds committed
70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98
			    0xffffffff00000000ULL)
				return -EOVERFLOW;
			/*
			 * f_files and f_ffree may be -1; it's okay to stuff
			 * that into 32 bits
			 */
			if (st.f_files != -1 &&
			    (st.f_files & 0xffffffff00000000ULL))
				return -EOVERFLOW;
			if (st.f_ffree != -1 &&
			    (st.f_ffree & 0xffffffff00000000ULL))
				return -EOVERFLOW;
		}

		buf->f_type = st.f_type;
		buf->f_bsize = st.f_bsize;
		buf->f_blocks = st.f_blocks;
		buf->f_bfree = st.f_bfree;
		buf->f_bavail = st.f_bavail;
		buf->f_files = st.f_files;
		buf->f_ffree = st.f_ffree;
		buf->f_fsid = st.f_fsid;
		buf->f_namelen = st.f_namelen;
		buf->f_frsize = st.f_frsize;
		memset(buf->f_spare, 0, sizeof(buf->f_spare));
	}
	return 0;
}

99
static int vfs_statfs64(struct dentry *dentry, struct statfs64 *buf)
Linus Torvalds's avatar
Linus Torvalds committed
100 101 102 103
{
	struct kstatfs st;
	int retval;

104
	retval = vfs_statfs(dentry, &st);
Linus Torvalds's avatar
Linus Torvalds committed
105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125
	if (retval)
		return retval;

	if (sizeof(*buf) == sizeof(st))
		memcpy(buf, &st, sizeof(st));
	else {
		buf->f_type = st.f_type;
		buf->f_bsize = st.f_bsize;
		buf->f_blocks = st.f_blocks;
		buf->f_bfree = st.f_bfree;
		buf->f_bavail = st.f_bavail;
		buf->f_files = st.f_files;
		buf->f_ffree = st.f_ffree;
		buf->f_fsid = st.f_fsid;
		buf->f_namelen = st.f_namelen;
		buf->f_frsize = st.f_frsize;
		memset(buf->f_spare, 0, sizeof(buf->f_spare));
	}
	return 0;
}

126
SYSCALL_DEFINE2(statfs, const char __user *, pathname, struct statfs __user *, buf)
Linus Torvalds's avatar
Linus Torvalds committed
127
{
128
	struct path path;
Linus Torvalds's avatar
Linus Torvalds committed
129 130
	int error;

131
	error = user_path(pathname, &path);
Linus Torvalds's avatar
Linus Torvalds committed
132 133
	if (!error) {
		struct statfs tmp;
134
		error = vfs_statfs_native(path.dentry, &tmp);
Linus Torvalds's avatar
Linus Torvalds committed
135 136
		if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
			error = -EFAULT;
137
		path_put(&path);
Linus Torvalds's avatar
Linus Torvalds committed
138 139 140 141
	}
	return error;
}

142
SYSCALL_DEFINE3(statfs64, const char __user *, pathname, size_t, sz, struct statfs64 __user *, buf)
Linus Torvalds's avatar
Linus Torvalds committed
143
{
144
	struct path path;
Linus Torvalds's avatar
Linus Torvalds committed
145 146 147 148
	long error;

	if (sz != sizeof(*buf))
		return -EINVAL;
149
	error = user_path(pathname, &path);
Linus Torvalds's avatar
Linus Torvalds committed
150 151
	if (!error) {
		struct statfs64 tmp;
152
		error = vfs_statfs64(path.dentry, &tmp);
Linus Torvalds's avatar
Linus Torvalds committed
153 154
		if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
			error = -EFAULT;
155
		path_put(&path);
Linus Torvalds's avatar
Linus Torvalds committed
156 157 158 159
	}
	return error;
}

160
SYSCALL_DEFINE2(fstatfs, unsigned int, fd, struct statfs __user *, buf)
Linus Torvalds's avatar
Linus Torvalds committed
161 162 163 164 165 166 167 168 169
{
	struct file * file;
	struct statfs tmp;
	int error;

	error = -EBADF;
	file = fget(fd);
	if (!file)
		goto out;
170
	error = vfs_statfs_native(file->f_path.dentry, &tmp);
Linus Torvalds's avatar
Linus Torvalds committed
171 172 173 174 175 176 177
	if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
		error = -EFAULT;
	fput(file);
out:
	return error;
}

178
SYSCALL_DEFINE3(fstatfs64, unsigned int, fd, size_t, sz, struct statfs64 __user *, buf)
Linus Torvalds's avatar
Linus Torvalds committed
179 180 181 182 183 184 185 186 187 188 189 190
{
	struct file * file;
	struct statfs64 tmp;
	int error;

	if (sz != sizeof(*buf))
		return -EINVAL;

	error = -EBADF;
	file = fget(fd);
	if (!file)
		goto out;
191
	error = vfs_statfs64(file->f_path.dentry, &tmp);
Linus Torvalds's avatar
Linus Torvalds committed
192 193 194 195 196 197 198
	if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
		error = -EFAULT;
	fput(file);
out:
	return error;
}

199 200
int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
	struct file *filp)
Linus Torvalds's avatar
Linus Torvalds committed
201
{
202
	int ret;
Linus Torvalds's avatar
Linus Torvalds committed
203 204 205 206 207 208 209
	struct iattr newattrs;

	/* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
	if (length < 0)
		return -EINVAL;

	newattrs.ia_size = length;
210
	newattrs.ia_valid = ATTR_SIZE | time_attrs;
211 212 213 214
	if (filp) {
		newattrs.ia_file = filp;
		newattrs.ia_valid |= ATTR_FILE;
	}
Linus Torvalds's avatar
Linus Torvalds committed
215

216
	/* Remove suid/sgid on truncate too */
217 218 219
	ret = should_remove_suid(dentry);
	if (ret)
		newattrs.ia_valid |= ret | ATTR_FORCE;
220

221
	mutex_lock(&dentry->d_inode->i_mutex);
222
	ret = notify_change(dentry, &newattrs);
223
	mutex_unlock(&dentry->d_inode->i_mutex);
224
	return ret;
Linus Torvalds's avatar
Linus Torvalds committed
225 226
}

227
static long do_sys_truncate(const char __user *pathname, loff_t length)
Linus Torvalds's avatar
Linus Torvalds committed
228
{
229 230
	struct path path;
	struct inode *inode;
Linus Torvalds's avatar
Linus Torvalds committed
231 232 233 234 235 236
	int error;

	error = -EINVAL;
	if (length < 0)	/* sorry, but loff_t says... */
		goto out;

237
	error = user_path(pathname, &path);
Linus Torvalds's avatar
Linus Torvalds committed
238 239
	if (error)
		goto out;
240
	inode = path.dentry->d_inode;
Linus Torvalds's avatar
Linus Torvalds committed
241 242 243 244 245 246 247 248 249 250

	/* For directories it's -EISDIR, for other non-regulars - -EINVAL */
	error = -EISDIR;
	if (S_ISDIR(inode->i_mode))
		goto dput_and_out;

	error = -EINVAL;
	if (!S_ISREG(inode->i_mode))
		goto dput_and_out;

251
	error = mnt_want_write(path.mnt);
Linus Torvalds's avatar
Linus Torvalds committed
252 253 254
	if (error)
		goto dput_and_out;

255
	error = inode_permission(inode, MAY_WRITE);
256 257
	if (error)
		goto mnt_drop_write_and_out;
Linus Torvalds's avatar
Linus Torvalds committed
258 259

	error = -EPERM;
260
	if (IS_APPEND(inode))
261
		goto mnt_drop_write_and_out;
Linus Torvalds's avatar
Linus Torvalds committed
262

263
	error = get_write_access(inode);
Linus Torvalds's avatar
Linus Torvalds committed
264
	if (error)
265
		goto mnt_drop_write_and_out;
Linus Torvalds's avatar
Linus Torvalds committed
266

267 268 269 270 271
	/*
	 * Make sure that there are no leases.  get_write_access() protects
	 * against the truncate racing with a lease-granting setlease().
	 */
	error = break_lease(inode, FMODE_WRITE);
Linus Torvalds's avatar
Linus Torvalds committed
272
	if (error)
273
		goto put_write_and_out;
Linus Torvalds's avatar
Linus Torvalds committed
274 275

	error = locks_verify_truncate(inode, NULL, length);
276 277
	if (!error)
		error = security_path_truncate(&path, length, 0);
Linus Torvalds's avatar
Linus Torvalds committed
278
	if (!error) {
279
		vfs_dq_init(inode);
280
		error = do_truncate(path.dentry, length, 0, NULL);
Linus Torvalds's avatar
Linus Torvalds committed
281 282
	}

283 284
put_write_and_out:
	put_write_access(inode);
285
mnt_drop_write_and_out:
286
	mnt_drop_write(path.mnt);
Linus Torvalds's avatar
Linus Torvalds committed
287
dput_and_out:
288
	path_put(&path);
Linus Torvalds's avatar
Linus Torvalds committed
289 290 291 292
out:
	return error;
}

293
SYSCALL_DEFINE2(truncate, const char __user *, path, long, length)
Linus Torvalds's avatar
Linus Torvalds committed
294
{
295
	return do_sys_truncate(path, length);
Linus Torvalds's avatar
Linus Torvalds committed
296 297
}

298
static long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
Linus Torvalds's avatar
Linus Torvalds committed
299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316
{
	struct inode * inode;
	struct dentry *dentry;
	struct file * file;
	int error;

	error = -EINVAL;
	if (length < 0)
		goto out;
	error = -EBADF;
	file = fget(fd);
	if (!file)
		goto out;

	/* explicitly opened as large or we are on 64-bit box */
	if (file->f_flags & O_LARGEFILE)
		small = 0;

317
	dentry = file->f_path.dentry;
Linus Torvalds's avatar
Linus Torvalds committed
318 319 320 321 322 323 324 325 326 327 328 329 330 331 332
	inode = dentry->d_inode;
	error = -EINVAL;
	if (!S_ISREG(inode->i_mode) || !(file->f_mode & FMODE_WRITE))
		goto out_putf;

	error = -EINVAL;
	/* Cannot ftruncate over 2^31 bytes without large file support */
	if (small && length > MAX_NON_LFS)
		goto out_putf;

	error = -EPERM;
	if (IS_APPEND(inode))
		goto out_putf;

	error = locks_verify_truncate(inode, file, length);
333 334 335
	if (!error)
		error = security_path_truncate(&file->f_path, length,
					       ATTR_MTIME|ATTR_CTIME);
Linus Torvalds's avatar
Linus Torvalds committed
336
	if (!error)
337
		error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, file);
Linus Torvalds's avatar
Linus Torvalds committed
338 339 340 341 342 343
out_putf:
	fput(file);
out:
	return error;
}

344
SYSCALL_DEFINE2(ftruncate, unsigned int, fd, unsigned long, length)
Linus Torvalds's avatar
Linus Torvalds committed
345
{
346
	long ret = do_sys_ftruncate(fd, length, 1);
347
	/* avoid REGPARM breakage on x86: */
348
	asmlinkage_protect(2, ret, fd, length);
349
	return ret;
Linus Torvalds's avatar
Linus Torvalds committed
350 351 352 353
}

/* LFS versions of truncate are only needed on 32 bit machines */
#if BITS_PER_LONG == 32
354
SYSCALL_DEFINE(truncate64)(const char __user * path, loff_t length)
Linus Torvalds's avatar
Linus Torvalds committed
355 356 357
{
	return do_sys_truncate(path, length);
}
358 359 360 361 362 363 364
#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
asmlinkage long SyS_truncate64(long path, loff_t length)
{
	return SYSC_truncate64((const char __user *) path, length);
}
SYSCALL_ALIAS(sys_truncate64, SyS_truncate64);
#endif
Linus Torvalds's avatar
Linus Torvalds committed
365

366
SYSCALL_DEFINE(ftruncate64)(unsigned int fd, loff_t length)
Linus Torvalds's avatar
Linus Torvalds committed
367
{
368
	long ret = do_sys_ftruncate(fd, length, 0);
369
	/* avoid REGPARM breakage on x86: */
370
	asmlinkage_protect(2, ret, fd, length);
371
	return ret;
Linus Torvalds's avatar
Linus Torvalds committed
372
}
373 374 375 376 377 378
#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
asmlinkage long SyS_ftruncate64(long fd, loff_t length)
{
	return SYSC_ftruncate64((unsigned int) fd, length);
}
SYSCALL_ALIAS(sys_ftruncate64, SyS_ftruncate64);
Linus Torvalds's avatar
Linus Torvalds committed
379
#endif
380
#endif /* BITS_PER_LONG == 32 */
Linus Torvalds's avatar
Linus Torvalds committed
381

382 383

int do_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
384
{
385 386
	struct inode *inode = file->f_path.dentry->d_inode;
	long ret;
387 388

	if (offset < 0 || len <= 0)
389
		return -EINVAL;
390 391 392

	/* Return error if mode is not supported */
	if (mode && !(mode & FALLOC_FL_KEEP_SIZE))
393
		return -EOPNOTSUPP;
394 395

	if (!(file->f_mode & FMODE_WRITE))
396
		return -EBADF;
397 398 399 400 401 402
	/*
	 * Revalidate the write permissions, in case security policy has
	 * changed since the files were opened.
	 */
	ret = security_file_permission(file, MAY_WRITE);
	if (ret)
403
		return ret;
404 405

	if (S_ISFIFO(inode->i_mode))
406
		return -ESPIPE;
407 408 409 410 411 412

	/*
	 * Let individual file system decide if it supports preallocation
	 * for directories or not.
	 */
	if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
413
		return -ENODEV;
414 415 416

	/* Check for wrap through zero too */
	if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
417
		return -EFBIG;
418

419 420
	if (!inode->i_op->fallocate)
		return -EOPNOTSUPP;
421

422 423 424 425 426 427 428 429 430 431 432 433 434 435 436
	return inode->i_op->fallocate(inode, mode, offset, len);
}

SYSCALL_DEFINE(fallocate)(int fd, int mode, loff_t offset, loff_t len)
{
	struct file *file;
	int error = -EBADF;

	file = fget(fd);
	if (file) {
		error = do_fallocate(file, mode, offset, len);
		fput(file);
	}

	return error;
437
}
438

439 440 441 442 443 444 445
#ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
asmlinkage long SyS_fallocate(long fd, long mode, loff_t offset, loff_t len)
{
	return SYSC_fallocate((int)fd, (int)mode, offset, len);
}
SYSCALL_ALIAS(sys_fallocate, SyS_fallocate);
#endif
446

Linus Torvalds's avatar
Linus Torvalds committed
447 448 449 450 451
/*
 * access() needs to use the real uid/gid, not the effective uid/gid.
 * We do this by temporarily clearing all FS-related capabilities and
 * switching the fsuid/fsgid around to the real ones.
 */
452
SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
Linus Torvalds's avatar
Linus Torvalds committed
453
{
454 455
	const struct cred *old_cred;
	struct cred *override_cred;
456
	struct path path;
457
	struct inode *inode;
Linus Torvalds's avatar
Linus Torvalds committed
458 459 460 461 462
	int res;

	if (mode & ~S_IRWXO)	/* where's F_OK, X_OK, W_OK, R_OK? */
		return -EINVAL;

463 464 465
	override_cred = prepare_creds();
	if (!override_cred)
		return -ENOMEM;
Linus Torvalds's avatar
Linus Torvalds committed
466

467 468
	override_cred->fsuid = override_cred->uid;
	override_cred->fsgid = override_cred->gid;
Linus Torvalds's avatar
Linus Torvalds committed
469

470
	if (!issecure(SECURE_NO_SETUID_FIXUP)) {
David Howells's avatar
David Howells committed
471
		/* Clear the capabilities if we switch to a non-root user */
472 473
		if (override_cred->uid)
			cap_clear(override_cred->cap_effective);
474
		else
475 476
			override_cred->cap_effective =
				override_cred->cap_permitted;
477
	}
Linus Torvalds's avatar
Linus Torvalds committed
478

479 480
	old_cred = override_creds(override_cred);

481
	res = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path);
482 483 484
	if (res)
		goto out;

485
	inode = path.dentry->d_inode;
486 487

	if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
488 489 490 491 492
		/*
		 * MAY_EXEC on regular files is denied if the fs is mounted
		 * with the "noexec" flag.
		 */
		res = -EACCES;
493
		if (path.mnt->mnt_flags & MNT_NOEXEC)
494 495 496
			goto out_path_release;
	}

497
	res = inode_permission(inode, mode | MAY_ACCESS);
498
	/* SuS v2 requires we report a read only fs too */
499
	if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
500
		goto out_path_release;
501 502 503 504 505 506 507 508 509 510
	/*
	 * This is a rare case where using __mnt_is_readonly()
	 * is OK without a mnt_want/drop_write() pair.  Since
	 * no actual write to the fs is performed here, we do
	 * not need to telegraph to that to anyone.
	 *
	 * By doing this, we accept that this access is
	 * inherently racy and know that the fs may change
	 * state before we even see this result.
	 */
511
	if (__mnt_is_readonly(path.mnt))
512
		res = -EROFS;
Linus Torvalds's avatar
Linus Torvalds committed
513

514
out_path_release:
515
	path_put(&path);
516
out:
517 518
	revert_creds(old_cred);
	put_cred(override_cred);
Linus Torvalds's avatar
Linus Torvalds committed
519 520 521
	return res;
}

522
SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
523 524 525 526
{
	return sys_faccessat(AT_FDCWD, filename, mode);
}

527
SYSCALL_DEFINE1(chdir, const char __user *, filename)
Linus Torvalds's avatar
Linus Torvalds committed
528
{
529
	struct path path;
Linus Torvalds's avatar
Linus Torvalds committed
530 531
	int error;

532
	error = user_path_dir(filename, &path);
Linus Torvalds's avatar
Linus Torvalds committed
533 534 535
	if (error)
		goto out;

536
	error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_ACCESS);
Linus Torvalds's avatar
Linus Torvalds committed
537 538 539
	if (error)
		goto dput_and_out;

540
	set_fs_pwd(current->fs, &path);
Linus Torvalds's avatar
Linus Torvalds committed
541 542

dput_and_out:
543
	path_put(&path);
Linus Torvalds's avatar
Linus Torvalds committed
544 545 546 547
out:
	return error;
}

548
SYSCALL_DEFINE1(fchdir, unsigned int, fd)
Linus Torvalds's avatar
Linus Torvalds committed
549 550 551 552 553 554 555 556 557 558
{
	struct file *file;
	struct inode *inode;
	int error;

	error = -EBADF;
	file = fget(fd);
	if (!file)
		goto out;

559
	inode = file->f_path.dentry->d_inode;
Linus Torvalds's avatar
Linus Torvalds committed
560 561 562 563 564

	error = -ENOTDIR;
	if (!S_ISDIR(inode->i_mode))
		goto out_putf;

565
	error = inode_permission(inode, MAY_EXEC | MAY_ACCESS);
Linus Torvalds's avatar
Linus Torvalds committed
566
	if (!error)
567
		set_fs_pwd(current->fs, &file->f_path);
Linus Torvalds's avatar
Linus Torvalds committed
568 569 570 571 572 573
out_putf:
	fput(file);
out:
	return error;
}

574
SYSCALL_DEFINE1(chroot, const char __user *, filename)
Linus Torvalds's avatar
Linus Torvalds committed
575
{
576
	struct path path;
Linus Torvalds's avatar
Linus Torvalds committed
577 578
	int error;

579
	error = user_path_dir(filename, &path);
Linus Torvalds's avatar
Linus Torvalds committed
580 581 582
	if (error)
		goto out;

583
	error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_ACCESS);
Linus Torvalds's avatar
Linus Torvalds committed
584 585 586 587 588 589 590
	if (error)
		goto dput_and_out;

	error = -EPERM;
	if (!capable(CAP_SYS_CHROOT))
		goto dput_and_out;

591
	set_fs_root(current->fs, &path);
Linus Torvalds's avatar
Linus Torvalds committed
592 593
	error = 0;
dput_and_out:
594
	path_put(&path);
Linus Torvalds's avatar
Linus Torvalds committed
595 596 597 598
out:
	return error;
}

599
SYSCALL_DEFINE2(fchmod, unsigned int, fd, mode_t, mode)
Linus Torvalds's avatar
Linus Torvalds committed
600 601 602 603 604 605 606 607 608 609 610
{
	struct inode * inode;
	struct dentry * dentry;
	struct file * file;
	int err = -EBADF;
	struct iattr newattrs;

	file = fget(fd);
	if (!file)
		goto out;

611
	dentry = file->f_path.dentry;
Linus Torvalds's avatar
Linus Torvalds committed
612 613
	inode = dentry->d_inode;

614
	audit_inode(NULL, dentry);
615

616
	err = mnt_want_write_file(file);
617
	if (err)
Linus Torvalds's avatar
Linus Torvalds committed
618
		goto out_putf;
619 620 621
	err = security_path_chmod(dentry, file->f_vfsmnt, mode);
	if (err)
		goto out_drop_write;
622
	mutex_lock(&inode->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
623 624 625 626 627
	if (mode == (mode_t) -1)
		mode = inode->i_mode;
	newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
	newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
	err = notify_change(dentry, &newattrs);
628
	mutex_unlock(&inode->i_mutex);
629
out_drop_write:
630
	mnt_drop_write(file->f_path.mnt);
Linus Torvalds's avatar
Linus Torvalds committed
631 632 633 634 635 636
out_putf:
	fput(file);
out:
	return err;
}

637
SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, mode_t, mode)
Linus Torvalds's avatar
Linus Torvalds committed
638
{
639 640
	struct path path;
	struct inode *inode;
Linus Torvalds's avatar
Linus Torvalds committed
641 642 643
	int error;
	struct iattr newattrs;

644
	error = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path);
Linus Torvalds's avatar
Linus Torvalds committed
645 646
	if (error)
		goto out;
647
	inode = path.dentry->d_inode;
Linus Torvalds's avatar
Linus Torvalds committed
648

649
	error = mnt_want_write(path.mnt);
650
	if (error)
Linus Torvalds's avatar
Linus Torvalds committed
651
		goto dput_and_out;
652 653 654
	error = security_path_chmod(path.dentry, path.mnt, mode);
	if (error)
		goto out_drop_write;
655
	mutex_lock(&inode->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
656 657 658 659
	if (mode == (mode_t) -1)
		mode = inode->i_mode;
	newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
	newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
660
	error = notify_change(path.dentry, &newattrs);
661
	mutex_unlock(&inode->i_mutex);
662
out_drop_write:
663
	mnt_drop_write(path.mnt);
Linus Torvalds's avatar
Linus Torvalds committed
664
dput_and_out:
665
	path_put(&path);
Linus Torvalds's avatar
Linus Torvalds committed
666 667 668 669
out:
	return error;
}

670
SYSCALL_DEFINE2(chmod, const char __user *, filename, mode_t, mode)
671 672 673 674
{
	return sys_fchmodat(AT_FDCWD, filename, mode);
}

Linus Torvalds's avatar
Linus Torvalds committed
675 676
static int chown_common(struct dentry * dentry, uid_t user, gid_t group)
{
677
	struct inode *inode = dentry->d_inode;
Linus Torvalds's avatar
Linus Torvalds committed
678 679 680 681 682 683 684 685 686 687 688 689 690
	int error;
	struct iattr newattrs;

	newattrs.ia_valid =  ATTR_CTIME;
	if (user != (uid_t) -1) {
		newattrs.ia_valid |= ATTR_UID;
		newattrs.ia_uid = user;
	}
	if (group != (gid_t) -1) {
		newattrs.ia_valid |= ATTR_GID;
		newattrs.ia_gid = group;
	}
	if (!S_ISDIR(inode->i_mode))
691 692
		newattrs.ia_valid |=
			ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
693
	mutex_lock(&inode->i_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
694
	error = notify_change(dentry, &newattrs);
695
	mutex_unlock(&inode->i_mutex);
696

Linus Torvalds's avatar
Linus Torvalds committed
697 698 699
	return error;
}

700
SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
Linus Torvalds's avatar
Linus Torvalds committed
701
{
702
	struct path path;
Linus Torvalds's avatar
Linus Torvalds committed
703 704
	int error;

705
	error = user_path(filename, &path);
706 707
	if (error)
		goto out;
708
	error = mnt_want_write(path.mnt);
709 710
	if (error)
		goto out_release;
711 712 713
	error = security_path_chown(&path, user, group);
	if (!error)
		error = chown_common(path.dentry, user, group);
714
	mnt_drop_write(path.mnt);
715
out_release:
716
	path_put(&path);
717
out:
Linus Torvalds's avatar
Linus Torvalds committed
718 719 720
	return error;
}

721 722
SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
		gid_t, group, int, flag)
723
{
724
	struct path path;
725 726 727 728 729 730 731
	int error = -EINVAL;
	int follow;

	if ((flag & ~AT_SYMLINK_NOFOLLOW) != 0)
		goto out;

	follow = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
732
	error = user_path_at(dfd, filename, follow, &path);
733 734
	if (error)
		goto out;
735
	error = mnt_want_write(path.mnt);
736 737
	if (error)
		goto out_release;
738 739 740
	error = security_path_chown(&path, user, group);
	if (!error)
		error = chown_common(path.dentry, user, group);
741
	mnt_drop_write(path.mnt);
742
out_release:
743
	path_put(&path);
744 745 746 747
out:
	return error;
}

748
SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
Linus Torvalds's avatar
Linus Torvalds committed
749
{
750
	struct path path;
Linus Torvalds's avatar
Linus Torvalds committed
751 752
	int error;

753
	error = user_lpath(filename, &path);
754 755
	if (error)
		goto out;
756
	error = mnt_want_write(path.mnt);
757 758
	if (error)
		goto out_release;
759 760 761
	error = security_path_chown(&path, user, group);
	if (!error)
		error = chown_common(path.dentry, user, group);
762
	mnt_drop_write(path.mnt);
763
out_release:
764
	path_put(&path);
765
out:
Linus Torvalds's avatar
Linus Torvalds committed
766 767 768
	return error;
}

769
SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
Linus Torvalds's avatar
Linus Torvalds committed
770 771 772
{
	struct file * file;
	int error = -EBADF;
773
	struct dentry * dentry;
Linus Torvalds's avatar
Linus Torvalds committed
774 775

	file = fget(fd);
776 777 778
	if (!file)
		goto out;

779
	error = mnt_want_write_file(file);
780 781
	if (error)
		goto out_fput;
782
	dentry = file->f_path.dentry;
783
	audit_inode(NULL, dentry);
784 785 786
	error = security_path_chown(&file->f_path, user, group);
	if (!error)
		error = chown_common(dentry, user, group);
787 788
	mnt_drop_write(file->f_path.mnt);
out_fput:
789 790
	fput(file);
out:
Linus Torvalds's avatar
Linus Torvalds committed
791 792 793
	return error;
}

794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822
/*
 * You have to be very careful that these write
 * counts get cleaned up in error cases and
 * upon __fput().  This should probably never
 * be called outside of __dentry_open().
 */
static inline int __get_file_write_access(struct inode *inode,
					  struct vfsmount *mnt)
{
	int error;
	error = get_write_access(inode);
	if (error)
		return error;
	/*
	 * Do not take mount writer counts on
	 * special files since no writes to
	 * the mount itself will occur.
	 */
	if (!special_file(inode->i_mode)) {
		/*
		 * Balanced in __fput()
		 */
		error = mnt_want_write(mnt);
		if (error)
			put_write_access(inode);
	}
	return error;
}

823
static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
824
					int flags, struct file *f,
825 826
					int (*open)(struct inode *, struct file *),
					const struct cred *cred)
Linus Torvalds's avatar
Linus Torvalds committed
827 828 829 830 831
{
	struct inode *inode;
	int error;

	f->f_flags = flags;
832
	f->f_mode = (__force fmode_t)((flags+1) & O_ACCMODE) | FMODE_LSEEK |
833
				FMODE_PREAD | FMODE_PWRITE;
Linus Torvalds's avatar
Linus Torvalds committed
834 835
	inode = dentry->d_inode;
	if (f->f_mode & FMODE_WRITE) {
836
		error = __get_file_write_access(inode, mnt);
Linus Torvalds's avatar
Linus Torvalds committed
837 838
		if (error)
			goto cleanup_file;
839 840
		if (!special_file(inode->i_mode))
			file_take_write(f);
Linus Torvalds's avatar
Linus Torvalds committed
841 842 843
	}

	f->f_mapping = inode->i_mapping;
844 845
	f->f_path.dentry = dentry;
	f->f_path.mnt = mnt;
Linus Torvalds's avatar
Linus Torvalds committed
846 847 848 849
	f->f_pos = 0;
	f->f_op = fops_get(inode->i_fop);
	file_move(f, &inode->i_sb->s_files);

850
	error = security_dentry_open(f, cred);
851 852 853
	if (error)
		goto cleanup_all;

854 855 856 857
	if (!open && f->f_op)
		open = f->f_op->open;
	if (open) {
		error = open(inode, f);
Linus Torvalds's avatar
Linus Torvalds committed
858 859 860
		if (error)
			goto cleanup_all;
	}
861

Linus Torvalds's avatar
Linus Torvalds committed
862 863 864 865 866 867
	f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);

	file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);

	/* NB: we're sure to have correct a_ops only after f_op->open */
	if (f->f_flags & O_DIRECT) {
868 869
		if (!f->f_mapping->a_ops ||
		    ((!f->f_mapping->a_ops->direct_IO) &&
870
		    (!f->f_mapping->a_ops->get_xip_mem))) {
Linus Torvalds's avatar
Linus Torvalds committed
871 872 873 874 875 876 877 878 879
			fput(f);
			f = ERR_PTR(-EINVAL);
		}
	}

	return f;

cleanup_all:
	fops_put(f->f_op);
880
	if (f->f_mode & FMODE_WRITE) {
Linus Torvalds's avatar
Linus Torvalds committed
881
		put_write_access(inode);
882 883 884 885 886 887 888 889
		if (!special_file(inode->i_mode)) {
			/*
			 * We don't consider this a real
			 * mnt_want/drop_write() pair
			 * because it all happenend right
			 * here, so just reset the state.
			 */
			file_reset_write(f);
890
			mnt_drop_write(mnt);
891
		}
892
	}
Linus Torvalds's avatar
Linus Torvalds committed
893
	file_kill(f);
894 895
	f->f_path.dentry = NULL;
	f->f_path.mnt = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
896 897 898 899 900 901 902
cleanup_file:
	put_filp(f);
	dput(dentry);
	mntput(mnt);
	return ERR_PTR(error);
}

903 904 905 906 907 908 909 910 911 912
/**
 * lookup_instantiate_filp - instantiates the open intent filp
 * @nd: pointer to nameidata
 * @dentry: pointer to dentry
 * @open: open callback
 *
 * Helper for filesystems that want to use lookup open intents and pass back
 * a fully instantiated struct file to the caller.
 * This function is meant to be called from within a filesystem's
 * lookup method.
913 914 915 916
 * Beware of calling it for non-regular files! Those ->open methods might block
 * (e.g. in fifo_open), leaving you with parent locked (and in case of fifo,
 * leading to a deadlock, as nobody can open that fifo anymore, because
 * another process to open fifo will block on locked parent when doing lookup).
917 918 919 920 921 922 923 924
 * Note that in case of error, nd->intent.open.file is destroyed, but the
 * path information remains valid.
 * If the open callback is set to NULL, then the standard f_op->open()
 * filesystem callback is substituted.
 */
struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry,
		int (*open)(struct inode *, struct file *))
{
925 926
	const struct cred *cred = current_cred();

927 928 929 930
	if (IS_ERR(nd->intent.open.file))
		goto out;
	if (IS_ERR(dentry))
		goto out_err;
931
	nd->intent.open.file = __dentry_open(dget(dentry), mntget(nd->path.mnt),
932 933
					     nd->intent.open.flags - 1,
					     nd->intent.open.file,
934
					     open, cred);
935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952
out:
	return nd->intent.open.file;
out_err:
	release_open_intent(nd);
	nd->intent.open.file = (struct file *)dentry;
	goto out;
}
EXPORT_SYMBOL_GPL(lookup_instantiate_filp);

/**
 * nameidata_to_filp - convert a nameidata to an open filp.
 * @nd: pointer to nameidata
 * @flags: open flags
 *
 * Note that this function destroys the original nameidata
 */
struct file *nameidata_to_filp(struct nameidata *nd, int flags)
{
953
	const struct cred *cred = current_cred();
954 955 956 957 958
	struct file *filp;

	/* Pick up the filp from the open intent */
	filp = nd->intent.open.file;
	/* Has the filesystem initialised the file for us? */
959
	if (filp->f_path.dentry == NULL)
960
		filp = __dentry_open(nd->path.dentry, nd->path.mnt, flags, filp,
961
				     NULL, cred);
962
	else
Jan Blunck's avatar
Jan Blunck committed
963
		path_put(&nd->path);
964 965 966
	return filp;
}

967 968 969 970
/*
 * dentry_open() will have done dput(dentry) and mntput(mnt) if it returns an
 * error.
 */
971 972
struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags,
			 const struct cred *cred)
973 974 975 976
{
	int error;
	struct file *f;

977 978
	validate_creds(cred);

979 980 981 982 983 984 985 986 987 988 989 990
	/*
	 * We must always pass in a valid mount pointer.   Historically
	 * callers got away with not passing it, but we must enforce this at
	 * the earliest possible point now to avoid strange problems deep in the
	 * filesystem stack.
	 */
	if (!mnt) {
		printk(KERN_WARNING "%s called with NULL vfsmount\n", __func__);
		dump_stack();
		return ERR_PTR(-EINVAL);
	}

991 992
	error = -ENFILE;
	f = get_empty_filp();
993 994 995
	if (f == NULL) {
		dput(dentry);
		mntput(mnt);
996
		return ERR_PTR(error);
997
	}
998

999
	return __dentry_open(dentry, mnt, flags, f, NULL, cred);
1000
}
Linus Torvalds's avatar
Linus Torvalds committed
1001 1002
EXPORT_SYMBOL(dentry_open);

1003
static void __put_unused_fd(struct files_struct *files, unsigned int fd)
Linus Torvalds's avatar
Linus Torvalds committed
1004
{
1005 1006