fcntl.c 13 KB
Newer Older
Linus Torvalds's avatar
Linus Torvalds committed
1 2 3 4 5 6 7 8 9 10 11
/*
 *  linux/fs/fcntl.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

#include <linux/syscalls.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/file.h>
Al Viro's avatar
Al Viro committed
12
#include <linux/fdtable.h>
13
#include <linux/capability.h>
Linus Torvalds's avatar
Linus Torvalds committed
14 15 16 17 18
#include <linux/dnotify.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/security.h>
#include <linux/ptrace.h>
19
#include <linux/signal.h>
20
#include <linux/rcupdate.h>
21
#include <linux/pid_namespace.h>
Linus Torvalds's avatar
Linus Torvalds committed
22 23 24 25 26

#include <asm/poll.h>
#include <asm/siginfo.h>
#include <asm/uaccess.h>

27
void set_close_on_exec(unsigned int fd, int flag)
Linus Torvalds's avatar
Linus Torvalds committed
28 29
{
	struct files_struct *files = current->files;
30
	struct fdtable *fdt;
Linus Torvalds's avatar
Linus Torvalds committed
31
	spin_lock(&files->file_lock);
32
	fdt = files_fdtable(files);
Linus Torvalds's avatar
Linus Torvalds committed
33
	if (flag)
34
		FD_SET(fd, fdt->close_on_exec);
Linus Torvalds's avatar
Linus Torvalds committed
35
	else
36
		FD_CLR(fd, fdt->close_on_exec);
Linus Torvalds's avatar
Linus Torvalds committed
37 38 39
	spin_unlock(&files->file_lock);
}

40
static int get_close_on_exec(unsigned int fd)
Linus Torvalds's avatar
Linus Torvalds committed
41 42
{
	struct files_struct *files = current->files;
43
	struct fdtable *fdt;
Linus Torvalds's avatar
Linus Torvalds committed
44
	int res;
45
	rcu_read_lock();
46 47
	fdt = files_fdtable(files);
	res = FD_ISSET(fd, fdt->close_on_exec);
48
	rcu_read_unlock();
Linus Torvalds's avatar
Linus Torvalds committed
49 50 51
	return res;
}

Ulrich Drepper's avatar
Ulrich Drepper committed
52
asmlinkage long sys_dup3(unsigned int oldfd, unsigned int newfd, int flags)
Linus Torvalds's avatar
Linus Torvalds committed
53 54 55 56
{
	int err = -EBADF;
	struct file * file, *tofree;
	struct files_struct * files = current->files;
57
	struct fdtable *fdt;
Linus Torvalds's avatar
Linus Torvalds committed
58

Ulrich Drepper's avatar
Ulrich Drepper committed
59 60 61
	if ((flags & ~O_CLOEXEC) != 0)
		return -EINVAL;

62 63 64
	if (unlikely(oldfd == newfd))
		return -EINVAL;

Linus Torvalds's avatar
Linus Torvalds committed
65 66 67 68 69 70
	spin_lock(&files->file_lock);
	if (!(file = fcheck(oldfd)))
		goto out_unlock;
	get_file(file);			/* We are now finished with oldfd */

	err = expand_files(files, newfd);
Al Viro's avatar
Al Viro committed
71 72 73
	if (unlikely(err < 0)) {
		if (err == -EMFILE)
			err = -EBADF;
Linus Torvalds's avatar
Linus Torvalds committed
74
		goto out_fput;
Al Viro's avatar
Al Viro committed
75
	}
Linus Torvalds's avatar
Linus Torvalds committed
76 77 78 79 80 81 82 83 84 85

	/* To avoid races with open() and dup(), we will mark the fd as
	 * in-use in the open-file bitmap throughout the entire dup2()
	 * process.  This is quite safe: do_close() uses the fd array
	 * entry, not the bitmap, to decide what work needs to be
	 * done.  --sct */
	/* Doesn't work. open() might be there first. --AV */

	/* Yes. It's a race. In user space. Nothing sane to do */
	err = -EBUSY;
86 87 88
	fdt = files_fdtable(files);
	tofree = fdt->fd[newfd];
	if (!tofree && FD_ISSET(newfd, fdt->open_fds))
Linus Torvalds's avatar
Linus Torvalds committed
89 90
		goto out_fput;

91
	rcu_assign_pointer(fdt->fd[newfd], file);
92
	FD_SET(newfd, fdt->open_fds);
Ulrich Drepper's avatar
Ulrich Drepper committed
93 94 95 96
	if (flags & O_CLOEXEC)
		FD_SET(newfd, fdt->close_on_exec);
	else
		FD_CLR(newfd, fdt->close_on_exec);
Linus Torvalds's avatar
Linus Torvalds committed
97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112
	spin_unlock(&files->file_lock);

	if (tofree)
		filp_close(tofree, files);
	err = newfd;
out:
	return err;
out_unlock:
	spin_unlock(&files->file_lock);
	goto out;

out_fput:
	spin_unlock(&files->file_lock);
	fput(file);
	goto out;
}
Ulrich Drepper's avatar
Ulrich Drepper committed
113 114 115

asmlinkage long sys_dup2(unsigned int oldfd, unsigned int newfd)
{
116 117 118 119 120 121 122 123
	if (unlikely(newfd == oldfd)) { /* corner case */
		struct files_struct *files = current->files;
		rcu_read_lock();
		if (!fcheck_files(files, oldfd))
			oldfd = -EBADF;
		rcu_read_unlock();
		return oldfd;
	}
Ulrich Drepper's avatar
Ulrich Drepper committed
124 125
	return sys_dup3(oldfd, newfd, 0);
}
Linus Torvalds's avatar
Linus Torvalds committed
126 127 128 129

asmlinkage long sys_dup(unsigned int fildes)
{
	int ret = -EBADF;
130 131 132 133 134 135 136 137 138
	struct file *file = fget(fildes);

	if (file) {
		ret = get_unused_fd();
		if (ret >= 0)
			fd_install(ret, file);
		else
			fput(file);
	}
Linus Torvalds's avatar
Linus Torvalds committed
139 140 141 142 143 144 145
	return ret;
}

#define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | FASYNC | O_DIRECT | O_NOATIME)

static int setfl(int fd, struct file * filp, unsigned long arg)
{
146
	struct inode * inode = filp->f_path.dentry->d_inode;
Linus Torvalds's avatar
Linus Torvalds committed
147 148
	int error = 0;

149 150 151 152 153
	/*
	 * O_APPEND cannot be cleared if the file is marked as append-only
	 * and the file is open for write.
	 */
	if (((arg ^ filp->f_flags) & O_APPEND) && IS_APPEND(inode))
Linus Torvalds's avatar
Linus Torvalds committed
154 155 156 157
		return -EPERM;

	/* O_NOATIME can only be set by the owner or superuser */
	if ((arg & O_NOATIME) && !(filp->f_flags & O_NOATIME))
158
		if (!is_owner_or_cap(inode))
Linus Torvalds's avatar
Linus Torvalds committed
159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189
			return -EPERM;

	/* required for strict SunOS emulation */
	if (O_NONBLOCK != O_NDELAY)
	       if (arg & O_NDELAY)
		   arg |= O_NONBLOCK;

	if (arg & O_DIRECT) {
		if (!filp->f_mapping || !filp->f_mapping->a_ops ||
			!filp->f_mapping->a_ops->direct_IO)
				return -EINVAL;
	}

	if (filp->f_op && filp->f_op->check_flags)
		error = filp->f_op->check_flags(arg);
	if (error)
		return error;

	if ((arg ^ filp->f_flags) & FASYNC) {
		if (filp->f_op && filp->f_op->fasync) {
			error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0);
			if (error < 0)
				goto out;
		}
	}

	filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK);
 out:
	return error;
}

190
static void f_modown(struct file *filp, struct pid *pid, enum pid_type type,
Linus Torvalds's avatar
Linus Torvalds committed
191 192 193 194
                     uid_t uid, uid_t euid, int force)
{
	write_lock_irq(&filp->f_owner.lock);
	if (force || !filp->f_owner.pid) {
195 196 197
		put_pid(filp->f_owner.pid);
		filp->f_owner.pid = get_pid(pid);
		filp->f_owner.pid_type = type;
Linus Torvalds's avatar
Linus Torvalds committed
198 199 200 201 202 203
		filp->f_owner.uid = uid;
		filp->f_owner.euid = euid;
	}
	write_unlock_irq(&filp->f_owner.lock);
}

204 205
int __f_setown(struct file *filp, struct pid *pid, enum pid_type type,
		int force)
Linus Torvalds's avatar
Linus Torvalds committed
206 207 208 209 210 211 212
{
	int err;
	
	err = security_file_set_fowner(filp);
	if (err)
		return err;

213
	f_modown(filp, pid, type, current->uid, current->euid, force);
Linus Torvalds's avatar
Linus Torvalds committed
214 215
	return 0;
}
216
EXPORT_SYMBOL(__f_setown);
Linus Torvalds's avatar
Linus Torvalds committed
217

218 219 220 221 222 223 224 225 226 227 228 229
int f_setown(struct file *filp, unsigned long arg, int force)
{
	enum pid_type type;
	struct pid *pid;
	int who = arg;
	int result;
	type = PIDTYPE_PID;
	if (who < 0) {
		type = PIDTYPE_PGID;
		who = -who;
	}
	rcu_read_lock();
230
	pid = find_vpid(who);
231 232 233 234
	result = __f_setown(filp, pid, type, force);
	rcu_read_unlock();
	return result;
}
Linus Torvalds's avatar
Linus Torvalds committed
235 236 237 238
EXPORT_SYMBOL(f_setown);

void f_delown(struct file *filp)
{
239 240 241 242 243 244
	f_modown(filp, NULL, PIDTYPE_PID, 0, 0, 1);
}

pid_t f_getown(struct file *filp)
{
	pid_t pid;
245
	read_lock(&filp->f_owner.lock);
246
	pid = pid_vnr(filp->f_owner.pid);
247 248
	if (filp->f_owner.pid_type == PIDTYPE_PGID)
		pid = -pid;
249
	read_unlock(&filp->f_owner.lock);
250
	return pid;
Linus Torvalds's avatar
Linus Torvalds committed
251 252 253 254 255 256 257 258 259
}

static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
		struct file *filp)
{
	long err = -EINVAL;

	switch (cmd) {
	case F_DUPFD:
260
	case F_DUPFD_CLOEXEC:
Al Viro's avatar
Al Viro committed
261 262
		if (arg >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur)
			break;
263 264 265 266 267
		err = alloc_fd(arg, cmd == F_DUPFD_CLOEXEC ? O_CLOEXEC : 0);
		if (err >= 0) {
			get_file(filp);
			fd_install(err, filp);
		}
Linus Torvalds's avatar
Linus Torvalds committed
268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286
		break;
	case F_GETFD:
		err = get_close_on_exec(fd) ? FD_CLOEXEC : 0;
		break;
	case F_SETFD:
		err = 0;
		set_close_on_exec(fd, arg & FD_CLOEXEC);
		break;
	case F_GETFL:
		err = filp->f_flags;
		break;
	case F_SETFL:
		err = setfl(fd, filp, arg);
		break;
	case F_GETLK:
		err = fcntl_getlk(filp, (struct flock __user *) arg);
		break;
	case F_SETLK:
	case F_SETLKW:
287
		err = fcntl_setlk(fd, filp, cmd, (struct flock __user *) arg);
Linus Torvalds's avatar
Linus Torvalds committed
288 289 290 291 292 293 294 295 296
		break;
	case F_GETOWN:
		/*
		 * XXX If f_owner is a process group, the
		 * negative return value will get converted
		 * into an error.  Oops.  If we keep the
		 * current syscall conventions, the only way
		 * to fix this will be in libc.
		 */
297
		err = f_getown(filp);
Linus Torvalds's avatar
Linus Torvalds committed
298 299 300 301 302 303 304 305 306 307
		force_successful_syscall_return();
		break;
	case F_SETOWN:
		err = f_setown(filp, arg, 1);
		break;
	case F_GETSIG:
		err = filp->f_owner.signum;
		break;
	case F_SETSIG:
		/* arg == 0 restores default behaviour. */
308
		if (!valid_signal(arg)) {
Linus Torvalds's avatar
Linus Torvalds committed
309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374
			break;
		}
		err = 0;
		filp->f_owner.signum = arg;
		break;
	case F_GETLEASE:
		err = fcntl_getlease(filp);
		break;
	case F_SETLEASE:
		err = fcntl_setlease(fd, filp, arg);
		break;
	case F_NOTIFY:
		err = fcntl_dirnotify(fd, filp, arg);
		break;
	default:
		break;
	}
	return err;
}

asmlinkage long sys_fcntl(unsigned int fd, unsigned int cmd, unsigned long arg)
{	
	struct file *filp;
	long err = -EBADF;

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

	err = security_file_fcntl(filp, cmd, arg);
	if (err) {
		fput(filp);
		return err;
	}

	err = do_fcntl(fd, cmd, arg, filp);

 	fput(filp);
out:
	return err;
}

#if BITS_PER_LONG == 32
asmlinkage long sys_fcntl64(unsigned int fd, unsigned int cmd, unsigned long arg)
{	
	struct file * filp;
	long err;

	err = -EBADF;
	filp = fget(fd);
	if (!filp)
		goto out;

	err = security_file_fcntl(filp, cmd, arg);
	if (err) {
		fput(filp);
		return err;
	}
	err = -EBADF;
	
	switch (cmd) {
		case F_GETLK64:
			err = fcntl_getlk64(filp, (struct flock64 __user *) arg);
			break;
		case F_SETLK64:
		case F_SETLKW64:
375 376
			err = fcntl_setlk64(fd, filp, cmd,
					(struct flock64 __user *) arg);
Linus Torvalds's avatar
Linus Torvalds committed
377 378 379 380 381 382 383 384 385 386 387 388 389
			break;
		default:
			err = do_fcntl(fd, cmd, arg, filp);
			break;
	}
	fput(filp);
out:
	return err;
}
#endif

/* Table to convert sigio signal codes into poll band bitmaps */

390
static const long band_table[NSIGPOLL] = {
Linus Torvalds's avatar
Linus Torvalds committed
391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430
	POLLIN | POLLRDNORM,			/* POLL_IN */
	POLLOUT | POLLWRNORM | POLLWRBAND,	/* POLL_OUT */
	POLLIN | POLLRDNORM | POLLMSG,		/* POLL_MSG */
	POLLERR,				/* POLL_ERR */
	POLLPRI | POLLRDBAND,			/* POLL_PRI */
	POLLHUP | POLLERR			/* POLL_HUP */
};

static inline int sigio_perm(struct task_struct *p,
                             struct fown_struct *fown, int sig)
{
	return (((fown->euid == 0) ||
		 (fown->euid == p->suid) || (fown->euid == p->uid) ||
		 (fown->uid == p->suid) || (fown->uid == p->uid)) &&
		!security_file_send_sigiotask(p, fown, sig));
}

static void send_sigio_to_task(struct task_struct *p,
			       struct fown_struct *fown, 
			       int fd,
			       int reason)
{
	if (!sigio_perm(p, fown, fown->signum))
		return;

	switch (fown->signum) {
		siginfo_t si;
		default:
			/* Queue a rt signal with the appropriate fd as its
			   value.  We use SI_SIGIO as the source, not 
			   SI_KERNEL, since kernel signals always get 
			   delivered even if we can't queue.  Failure to
			   queue in this case _should_ be reported; we fall
			   back to SIGIO in that case. --sct */
			si.si_signo = fown->signum;
			si.si_errno = 0;
		        si.si_code  = reason;
			/* Make sure we are called with one of the POLL_*
			   reasons, otherwise we could leak kernel stack into
			   userspace.  */
431
			BUG_ON((reason & __SI_MASK) != __SI_POLL);
Linus Torvalds's avatar
Linus Torvalds committed
432 433 434 435 436
			if (reason - POLL_IN >= NSIGPOLL)
				si.si_band  = ~0L;
			else
				si.si_band = band_table[reason - POLL_IN];
			si.si_fd    = fd;
437
			if (!group_send_sig_info(fown->signum, &si, p))
Linus Torvalds's avatar
Linus Torvalds committed
438 439 440
				break;
		/* fall-through: fall back on the old plain SIGIO signal */
		case 0:
441
			group_send_sig_info(SIGIO, SEND_SIG_PRIV, p);
Linus Torvalds's avatar
Linus Torvalds committed
442 443 444 445 446 447
	}
}

void send_sigio(struct fown_struct *fown, int fd, int band)
{
	struct task_struct *p;
448 449
	enum pid_type type;
	struct pid *pid;
Linus Torvalds's avatar
Linus Torvalds committed
450 451
	
	read_lock(&fown->lock);
452
	type = fown->pid_type;
Linus Torvalds's avatar
Linus Torvalds committed
453 454 455 456 457
	pid = fown->pid;
	if (!pid)
		goto out_unlock_fown;
	
	read_lock(&tasklist_lock);
458 459 460
	do_each_pid_task(pid, type, p) {
		send_sigio_to_task(p, fown, fd, band);
	} while_each_pid_task(pid, type, p);
Linus Torvalds's avatar
Linus Torvalds committed
461 462 463 464 465 466 467 468 469
	read_unlock(&tasklist_lock);
 out_unlock_fown:
	read_unlock(&fown->lock);
}

static void send_sigurg_to_task(struct task_struct *p,
                                struct fown_struct *fown)
{
	if (sigio_perm(p, fown, SIGURG))
470
		group_send_sig_info(SIGURG, SEND_SIG_PRIV, p);
Linus Torvalds's avatar
Linus Torvalds committed
471 472 473 474 475
}

int send_sigurg(struct fown_struct *fown)
{
	struct task_struct *p;
476 477 478
	enum pid_type type;
	struct pid *pid;
	int ret = 0;
Linus Torvalds's avatar
Linus Torvalds committed
479 480
	
	read_lock(&fown->lock);
481
	type = fown->pid_type;
Linus Torvalds's avatar
Linus Torvalds committed
482 483 484 485 486 487 488
	pid = fown->pid;
	if (!pid)
		goto out_unlock_fown;

	ret = 1;
	
	read_lock(&tasklist_lock);
489 490 491
	do_each_pid_task(pid, type, p) {
		send_sigurg_to_task(p, fown);
	} while_each_pid_task(pid, type, p);
Linus Torvalds's avatar
Linus Torvalds committed
492 493 494 495 496 497 498
	read_unlock(&tasklist_lock);
 out_unlock_fown:
	read_unlock(&fown->lock);
	return ret;
}

static DEFINE_RWLOCK(fasync_lock);
499
static struct kmem_cache *fasync_cache __read_mostly;
Linus Torvalds's avatar
Linus Torvalds committed
500 501 502 503 504 505 506 507 508 509 510 511 512

/*
 * fasync_helper() is used by some character device drivers (mainly mice)
 * to set up the fasync queue. It returns negative on error, 0 if it did
 * no changes and positive if it added/deleted the entry.
 */
int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp)
{
	struct fasync_struct *fa, **fp;
	struct fasync_struct *new = NULL;
	int result = 0;

	if (on) {
513
		new = kmem_cache_alloc(fasync_cache, GFP_KERNEL);
Linus Torvalds's avatar
Linus Torvalds committed
514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584
		if (!new)
			return -ENOMEM;
	}
	write_lock_irq(&fasync_lock);
	for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
		if (fa->fa_file == filp) {
			if(on) {
				fa->fa_fd = fd;
				kmem_cache_free(fasync_cache, new);
			} else {
				*fp = fa->fa_next;
				kmem_cache_free(fasync_cache, fa);
				result = 1;
			}
			goto out;
		}
	}

	if (on) {
		new->magic = FASYNC_MAGIC;
		new->fa_file = filp;
		new->fa_fd = fd;
		new->fa_next = *fapp;
		*fapp = new;
		result = 1;
	}
out:
	write_unlock_irq(&fasync_lock);
	return result;
}

EXPORT_SYMBOL(fasync_helper);

void __kill_fasync(struct fasync_struct *fa, int sig, int band)
{
	while (fa) {
		struct fown_struct * fown;
		if (fa->magic != FASYNC_MAGIC) {
			printk(KERN_ERR "kill_fasync: bad magic number in "
			       "fasync_struct!\n");
			return;
		}
		fown = &fa->fa_file->f_owner;
		/* Don't send SIGURG to processes which have not set a
		   queued signum: SIGURG has its own default signalling
		   mechanism. */
		if (!(sig == SIGURG && fown->signum == 0))
			send_sigio(fown, fa->fa_fd, band);
		fa = fa->fa_next;
	}
}

EXPORT_SYMBOL(__kill_fasync);

void kill_fasync(struct fasync_struct **fp, int sig, int band)
{
	/* First a quick test without locking: usually
	 * the list is empty.
	 */
	if (*fp) {
		read_lock(&fasync_lock);
		/* reread *fp after obtaining the lock */
		__kill_fasync(*fp, sig, band);
		read_unlock(&fasync_lock);
	}
}
EXPORT_SYMBOL(kill_fasync);

static int __init fasync_init(void)
{
	fasync_cache = kmem_cache_create("fasync_cache",
585
		sizeof(struct fasync_struct), 0, SLAB_PANIC, NULL);
Linus Torvalds's avatar
Linus Torvalds committed
586 587 588 589
	return 0;
}

module_init(fasync_init)