1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  linux/fs/fcntl.c
4  *
5  *  Copyright (C) 1991, 1992  Linus Torvalds
6  */
7 
8 #include <linux/syscalls.h>
9 #include <linux/init.h>
10 #include <linux/mm.h>
11 #include <linux/sched/task.h>
12 #include <linux/fs.h>
13 #include <linux/file.h>
14 #include <linux/fdtable.h>
15 #include <linux/capability.h>
16 #include <linux/dnotify.h>
17 #include <linux/slab.h>
18 #include <linux/module.h>
19 #include <linux/pipe_fs_i.h>
20 #include <linux/security.h>
21 #include <linux/ptrace.h>
22 #include <linux/signal.h>
23 #include <linux/rcupdate.h>
24 #include <linux/pid_namespace.h>
25 #include <linux/user_namespace.h>
26 #include <linux/memfd.h>
27 #include <linux/compat.h>
28 
29 #include <linux/poll.h>
30 #include <asm/siginfo.h>
31 #include <linux/uaccess.h>
32 
33 #define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT | O_NOATIME)
34 
setfl(int fd,struct file * filp,unsigned long arg)35 static int setfl(int fd, struct file * filp, unsigned long arg)
36 {
37 	struct inode * inode = file_inode(filp);
38 	int error = 0;
39 
40 	/*
41 	 * O_APPEND cannot be cleared if the file is marked as append-only
42 	 * and the file is open for write.
43 	 */
44 	if (((arg ^ filp->f_flags) & O_APPEND) && IS_APPEND(inode))
45 		return -EPERM;
46 
47 	/* O_NOATIME can only be set by the owner or superuser */
48 	if ((arg & O_NOATIME) && !(filp->f_flags & O_NOATIME))
49 		if (!inode_owner_or_capable(inode))
50 			return -EPERM;
51 
52 	/* required for strict SunOS emulation */
53 	if (O_NONBLOCK != O_NDELAY)
54 	       if (arg & O_NDELAY)
55 		   arg |= O_NONBLOCK;
56 
57 	/* Pipe packetized mode is controlled by O_DIRECT flag */
58 	if (!S_ISFIFO(inode->i_mode) && (arg & O_DIRECT)) {
59 		if (!filp->f_mapping || !filp->f_mapping->a_ops ||
60 			!filp->f_mapping->a_ops->direct_IO)
61 				return -EINVAL;
62 	}
63 
64 	if (filp->f_op->check_flags)
65 		error = filp->f_op->check_flags(arg);
66 	if (error)
67 		return error;
68 
69 	/*
70 	 * ->fasync() is responsible for setting the FASYNC bit.
71 	 */
72 	if (((arg ^ filp->f_flags) & FASYNC) && filp->f_op->fasync) {
73 		error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0);
74 		if (error < 0)
75 			goto out;
76 		if (error > 0)
77 			error = 0;
78 	}
79 	spin_lock(&filp->f_lock);
80 	filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK);
81 	spin_unlock(&filp->f_lock);
82 
83  out:
84 	return error;
85 }
86 
f_modown(struct file * filp,struct pid * pid,enum pid_type type,int force)87 static void f_modown(struct file *filp, struct pid *pid, enum pid_type type,
88                      int force)
89 {
90 	write_lock_irq(&filp->f_owner.lock);
91 	if (force || !filp->f_owner.pid) {
92 		put_pid(filp->f_owner.pid);
93 		filp->f_owner.pid = get_pid(pid);
94 		filp->f_owner.pid_type = type;
95 
96 		if (pid) {
97 			const struct cred *cred = current_cred();
98 			filp->f_owner.uid = cred->uid;
99 			filp->f_owner.euid = cred->euid;
100 		}
101 	}
102 	write_unlock_irq(&filp->f_owner.lock);
103 }
104 
__f_setown(struct file * filp,struct pid * pid,enum pid_type type,int force)105 void __f_setown(struct file *filp, struct pid *pid, enum pid_type type,
106 		int force)
107 {
108 	security_file_set_fowner(filp);
109 	f_modown(filp, pid, type, force);
110 }
111 EXPORT_SYMBOL(__f_setown);
112 
f_setown(struct file * filp,unsigned long arg,int force)113 int f_setown(struct file *filp, unsigned long arg, int force)
114 {
115 	enum pid_type type;
116 	struct pid *pid = NULL;
117 	int who = arg, ret = 0;
118 
119 	type = PIDTYPE_TGID;
120 	if (who < 0) {
121 		/* avoid overflow below */
122 		if (who == INT_MIN)
123 			return -EINVAL;
124 
125 		type = PIDTYPE_PGID;
126 		who = -who;
127 	}
128 
129 	rcu_read_lock();
130 	if (who) {
131 		pid = find_vpid(who);
132 		if (!pid)
133 			ret = -ESRCH;
134 	}
135 
136 	if (!ret)
137 		__f_setown(filp, pid, type, force);
138 	rcu_read_unlock();
139 
140 	return ret;
141 }
142 EXPORT_SYMBOL(f_setown);
143 
f_delown(struct file * filp)144 void f_delown(struct file *filp)
145 {
146 	f_modown(filp, NULL, PIDTYPE_TGID, 1);
147 }
148 
f_getown(struct file * filp)149 pid_t f_getown(struct file *filp)
150 {
151 	pid_t pid;
152 	read_lock(&filp->f_owner.lock);
153 	pid = pid_vnr(filp->f_owner.pid);
154 	if (filp->f_owner.pid_type == PIDTYPE_PGID)
155 		pid = -pid;
156 	read_unlock(&filp->f_owner.lock);
157 	return pid;
158 }
159 
f_setown_ex(struct file * filp,unsigned long arg)160 static int f_setown_ex(struct file *filp, unsigned long arg)
161 {
162 	struct f_owner_ex __user *owner_p = (void __user *)arg;
163 	struct f_owner_ex owner;
164 	struct pid *pid;
165 	int type;
166 	int ret;
167 
168 	ret = copy_from_user(&owner, owner_p, sizeof(owner));
169 	if (ret)
170 		return -EFAULT;
171 
172 	switch (owner.type) {
173 	case F_OWNER_TID:
174 		type = PIDTYPE_PID;
175 		break;
176 
177 	case F_OWNER_PID:
178 		type = PIDTYPE_TGID;
179 		break;
180 
181 	case F_OWNER_PGRP:
182 		type = PIDTYPE_PGID;
183 		break;
184 
185 	default:
186 		return -EINVAL;
187 	}
188 
189 	rcu_read_lock();
190 	pid = find_vpid(owner.pid);
191 	if (owner.pid && !pid)
192 		ret = -ESRCH;
193 	else
194 		 __f_setown(filp, pid, type, 1);
195 	rcu_read_unlock();
196 
197 	return ret;
198 }
199 
f_getown_ex(struct file * filp,unsigned long arg)200 static int f_getown_ex(struct file *filp, unsigned long arg)
201 {
202 	struct f_owner_ex __user *owner_p = (void __user *)arg;
203 	struct f_owner_ex owner;
204 	int ret = 0;
205 
206 	read_lock(&filp->f_owner.lock);
207 	owner.pid = pid_vnr(filp->f_owner.pid);
208 	switch (filp->f_owner.pid_type) {
209 	case PIDTYPE_PID:
210 		owner.type = F_OWNER_TID;
211 		break;
212 
213 	case PIDTYPE_TGID:
214 		owner.type = F_OWNER_PID;
215 		break;
216 
217 	case PIDTYPE_PGID:
218 		owner.type = F_OWNER_PGRP;
219 		break;
220 
221 	default:
222 		WARN_ON(1);
223 		ret = -EINVAL;
224 		break;
225 	}
226 	read_unlock(&filp->f_owner.lock);
227 
228 	if (!ret) {
229 		ret = copy_to_user(owner_p, &owner, sizeof(owner));
230 		if (ret)
231 			ret = -EFAULT;
232 	}
233 	return ret;
234 }
235 
236 #ifdef CONFIG_CHECKPOINT_RESTORE
f_getowner_uids(struct file * filp,unsigned long arg)237 static int f_getowner_uids(struct file *filp, unsigned long arg)
238 {
239 	struct user_namespace *user_ns = current_user_ns();
240 	uid_t __user *dst = (void __user *)arg;
241 	uid_t src[2];
242 	int err;
243 
244 	read_lock(&filp->f_owner.lock);
245 	src[0] = from_kuid(user_ns, filp->f_owner.uid);
246 	src[1] = from_kuid(user_ns, filp->f_owner.euid);
247 	read_unlock(&filp->f_owner.lock);
248 
249 	err  = put_user(src[0], &dst[0]);
250 	err |= put_user(src[1], &dst[1]);
251 
252 	return err;
253 }
254 #else
f_getowner_uids(struct file * filp,unsigned long arg)255 static int f_getowner_uids(struct file *filp, unsigned long arg)
256 {
257 	return -EINVAL;
258 }
259 #endif
260 
rw_hint_valid(enum rw_hint hint)261 static bool rw_hint_valid(enum rw_hint hint)
262 {
263 	switch (hint) {
264 	case RWF_WRITE_LIFE_NOT_SET:
265 	case RWH_WRITE_LIFE_NONE:
266 	case RWH_WRITE_LIFE_SHORT:
267 	case RWH_WRITE_LIFE_MEDIUM:
268 	case RWH_WRITE_LIFE_LONG:
269 	case RWH_WRITE_LIFE_EXTREME:
270 		return true;
271 	default:
272 		return false;
273 	}
274 }
275 
fcntl_rw_hint(struct file * file,unsigned int cmd,unsigned long arg)276 static long fcntl_rw_hint(struct file *file, unsigned int cmd,
277 			  unsigned long arg)
278 {
279 	struct inode *inode = file_inode(file);
280 	u64 *argp = (u64 __user *)arg;
281 	enum rw_hint hint;
282 	u64 h;
283 
284 	switch (cmd) {
285 	case F_GET_FILE_RW_HINT:
286 		h = file_write_hint(file);
287 		if (copy_to_user(argp, &h, sizeof(*argp)))
288 			return -EFAULT;
289 		return 0;
290 	case F_SET_FILE_RW_HINT:
291 		if (copy_from_user(&h, argp, sizeof(h)))
292 			return -EFAULT;
293 		hint = (enum rw_hint) h;
294 		if (!rw_hint_valid(hint))
295 			return -EINVAL;
296 
297 		spin_lock(&file->f_lock);
298 		file->f_write_hint = hint;
299 		spin_unlock(&file->f_lock);
300 		return 0;
301 	case F_GET_RW_HINT:
302 		h = inode->i_write_hint;
303 		if (copy_to_user(argp, &h, sizeof(*argp)))
304 			return -EFAULT;
305 		return 0;
306 	case F_SET_RW_HINT:
307 		if (copy_from_user(&h, argp, sizeof(h)))
308 			return -EFAULT;
309 		hint = (enum rw_hint) h;
310 		if (!rw_hint_valid(hint))
311 			return -EINVAL;
312 
313 		inode_lock(inode);
314 		inode->i_write_hint = hint;
315 		inode_unlock(inode);
316 		return 0;
317 	default:
318 		return -EINVAL;
319 	}
320 }
321 
do_fcntl(int fd,unsigned int cmd,unsigned long arg,struct file * filp)322 static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
323 		struct file *filp)
324 {
325 	void __user *argp = (void __user *)arg;
326 	struct flock flock;
327 	long err = -EINVAL;
328 
329 	switch (cmd) {
330 	case F_DUPFD:
331 		err = f_dupfd(arg, filp, 0);
332 		break;
333 	case F_DUPFD_CLOEXEC:
334 		err = f_dupfd(arg, filp, O_CLOEXEC);
335 		break;
336 	case F_GETFD:
337 		err = get_close_on_exec(fd) ? FD_CLOEXEC : 0;
338 		break;
339 	case F_SETFD:
340 		err = 0;
341 		set_close_on_exec(fd, arg & FD_CLOEXEC);
342 		break;
343 	case F_GETFL:
344 		err = filp->f_flags;
345 		break;
346 	case F_SETFL:
347 		err = setfl(fd, filp, arg);
348 		break;
349 #if BITS_PER_LONG != 32
350 	/* 32-bit arches must use fcntl64() */
351 	case F_OFD_GETLK:
352 #endif
353 	case F_GETLK:
354 		if (copy_from_user(&flock, argp, sizeof(flock)))
355 			return -EFAULT;
356 		err = fcntl_getlk(filp, cmd, &flock);
357 		if (!err && copy_to_user(argp, &flock, sizeof(flock)))
358 			return -EFAULT;
359 		break;
360 #if BITS_PER_LONG != 32
361 	/* 32-bit arches must use fcntl64() */
362 	case F_OFD_SETLK:
363 	case F_OFD_SETLKW:
364 #endif
365 		/* Fallthrough */
366 	case F_SETLK:
367 	case F_SETLKW:
368 		if (copy_from_user(&flock, argp, sizeof(flock)))
369 			return -EFAULT;
370 		err = fcntl_setlk(fd, filp, cmd, &flock);
371 		break;
372 	case F_GETOWN:
373 		/*
374 		 * XXX If f_owner is a process group, the
375 		 * negative return value will get converted
376 		 * into an error.  Oops.  If we keep the
377 		 * current syscall conventions, the only way
378 		 * to fix this will be in libc.
379 		 */
380 		err = f_getown(filp);
381 		force_successful_syscall_return();
382 		break;
383 	case F_SETOWN:
384 		err = f_setown(filp, arg, 1);
385 		break;
386 	case F_GETOWN_EX:
387 		err = f_getown_ex(filp, arg);
388 		break;
389 	case F_SETOWN_EX:
390 		err = f_setown_ex(filp, arg);
391 		break;
392 	case F_GETOWNER_UIDS:
393 		err = f_getowner_uids(filp, arg);
394 		break;
395 	case F_GETSIG:
396 		err = filp->f_owner.signum;
397 		break;
398 	case F_SETSIG:
399 		/* arg == 0 restores default behaviour. */
400 		if (!valid_signal(arg)) {
401 			break;
402 		}
403 		err = 0;
404 		filp->f_owner.signum = arg;
405 		break;
406 	case F_GETLEASE:
407 		err = fcntl_getlease(filp);
408 		break;
409 	case F_SETLEASE:
410 		err = fcntl_setlease(fd, filp, arg);
411 		break;
412 	case F_NOTIFY:
413 		err = fcntl_dirnotify(fd, filp, arg);
414 		break;
415 	case F_SETPIPE_SZ:
416 	case F_GETPIPE_SZ:
417 		err = pipe_fcntl(filp, cmd, arg);
418 		break;
419 	case F_ADD_SEALS:
420 	case F_GET_SEALS:
421 		err = memfd_fcntl(filp, cmd, arg);
422 		break;
423 	case F_GET_RW_HINT:
424 	case F_SET_RW_HINT:
425 	case F_GET_FILE_RW_HINT:
426 	case F_SET_FILE_RW_HINT:
427 		err = fcntl_rw_hint(filp, cmd, arg);
428 		break;
429 	default:
430 		break;
431 	}
432 	return err;
433 }
434 
check_fcntl_cmd(unsigned cmd)435 static int check_fcntl_cmd(unsigned cmd)
436 {
437 	switch (cmd) {
438 	case F_DUPFD:
439 	case F_DUPFD_CLOEXEC:
440 	case F_GETFD:
441 	case F_SETFD:
442 	case F_GETFL:
443 		return 1;
444 	}
445 	return 0;
446 }
447 
SYSCALL_DEFINE3(fcntl,unsigned int,fd,unsigned int,cmd,unsigned long,arg)448 SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
449 {
450 	struct fd f = fdget_raw(fd);
451 	long err = -EBADF;
452 
453 	if (!f.file)
454 		goto out;
455 
456 	if (unlikely(f.file->f_mode & FMODE_PATH)) {
457 		if (!check_fcntl_cmd(cmd))
458 			goto out1;
459 	}
460 
461 	err = security_file_fcntl(f.file, cmd, arg);
462 	if (!err)
463 		err = do_fcntl(fd, cmd, arg, f.file);
464 
465 out1:
466  	fdput(f);
467 out:
468 	return err;
469 }
470 
471 #if BITS_PER_LONG == 32
SYSCALL_DEFINE3(fcntl64,unsigned int,fd,unsigned int,cmd,unsigned long,arg)472 SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd,
473 		unsigned long, arg)
474 {
475 	void __user *argp = (void __user *)arg;
476 	struct fd f = fdget_raw(fd);
477 	struct flock64 flock;
478 	long err = -EBADF;
479 
480 	if (!f.file)
481 		goto out;
482 
483 	if (unlikely(f.file->f_mode & FMODE_PATH)) {
484 		if (!check_fcntl_cmd(cmd))
485 			goto out1;
486 	}
487 
488 	err = security_file_fcntl(f.file, cmd, arg);
489 	if (err)
490 		goto out1;
491 
492 	switch (cmd) {
493 	case F_GETLK64:
494 	case F_OFD_GETLK:
495 		err = -EFAULT;
496 		if (copy_from_user(&flock, argp, sizeof(flock)))
497 			break;
498 		err = fcntl_getlk64(f.file, cmd, &flock);
499 		if (!err && copy_to_user(argp, &flock, sizeof(flock)))
500 			err = -EFAULT;
501 		break;
502 	case F_SETLK64:
503 	case F_SETLKW64:
504 	case F_OFD_SETLK:
505 	case F_OFD_SETLKW:
506 		err = -EFAULT;
507 		if (copy_from_user(&flock, argp, sizeof(flock)))
508 			break;
509 		err = fcntl_setlk64(fd, f.file, cmd, &flock);
510 		break;
511 	default:
512 		err = do_fcntl(fd, cmd, arg, f.file);
513 		break;
514 	}
515 out1:
516 	fdput(f);
517 out:
518 	return err;
519 }
520 #endif
521 
522 #ifdef CONFIG_COMPAT
523 /* careful - don't use anywhere else */
524 #define copy_flock_fields(dst, src)		\
525 	(dst)->l_type = (src)->l_type;		\
526 	(dst)->l_whence = (src)->l_whence;	\
527 	(dst)->l_start = (src)->l_start;	\
528 	(dst)->l_len = (src)->l_len;		\
529 	(dst)->l_pid = (src)->l_pid;
530 
get_compat_flock(struct flock * kfl,const struct compat_flock __user * ufl)531 static int get_compat_flock(struct flock *kfl, const struct compat_flock __user *ufl)
532 {
533 	struct compat_flock fl;
534 
535 	if (copy_from_user(&fl, ufl, sizeof(struct compat_flock)))
536 		return -EFAULT;
537 	copy_flock_fields(kfl, &fl);
538 	return 0;
539 }
540 
get_compat_flock64(struct flock * kfl,const struct compat_flock64 __user * ufl)541 static int get_compat_flock64(struct flock *kfl, const struct compat_flock64 __user *ufl)
542 {
543 	struct compat_flock64 fl;
544 
545 	if (copy_from_user(&fl, ufl, sizeof(struct compat_flock64)))
546 		return -EFAULT;
547 	copy_flock_fields(kfl, &fl);
548 	return 0;
549 }
550 
put_compat_flock(const struct flock * kfl,struct compat_flock __user * ufl)551 static int put_compat_flock(const struct flock *kfl, struct compat_flock __user *ufl)
552 {
553 	struct compat_flock fl;
554 
555 	memset(&fl, 0, sizeof(struct compat_flock));
556 	copy_flock_fields(&fl, kfl);
557 	if (copy_to_user(ufl, &fl, sizeof(struct compat_flock)))
558 		return -EFAULT;
559 	return 0;
560 }
561 
put_compat_flock64(const struct flock * kfl,struct compat_flock64 __user * ufl)562 static int put_compat_flock64(const struct flock *kfl, struct compat_flock64 __user *ufl)
563 {
564 	struct compat_flock64 fl;
565 
566 	BUILD_BUG_ON(sizeof(kfl->l_start) > sizeof(ufl->l_start));
567 	BUILD_BUG_ON(sizeof(kfl->l_len) > sizeof(ufl->l_len));
568 
569 	memset(&fl, 0, sizeof(struct compat_flock64));
570 	copy_flock_fields(&fl, kfl);
571 	if (copy_to_user(ufl, &fl, sizeof(struct compat_flock64)))
572 		return -EFAULT;
573 	return 0;
574 }
575 #undef copy_flock_fields
576 
577 static unsigned int
convert_fcntl_cmd(unsigned int cmd)578 convert_fcntl_cmd(unsigned int cmd)
579 {
580 	switch (cmd) {
581 	case F_GETLK64:
582 		return F_GETLK;
583 	case F_SETLK64:
584 		return F_SETLK;
585 	case F_SETLKW64:
586 		return F_SETLKW;
587 	}
588 
589 	return cmd;
590 }
591 
592 /*
593  * GETLK was successful and we need to return the data, but it needs to fit in
594  * the compat structure.
595  * l_start shouldn't be too big, unless the original start + end is greater than
596  * COMPAT_OFF_T_MAX, in which case the app was asking for trouble, so we return
597  * -EOVERFLOW in that case.  l_len could be too big, in which case we just
598  * truncate it, and only allow the app to see that part of the conflicting lock
599  * that might make sense to it anyway
600  */
fixup_compat_flock(struct flock * flock)601 static int fixup_compat_flock(struct flock *flock)
602 {
603 	if (flock->l_start > COMPAT_OFF_T_MAX)
604 		return -EOVERFLOW;
605 	if (flock->l_len > COMPAT_OFF_T_MAX)
606 		flock->l_len = COMPAT_OFF_T_MAX;
607 	return 0;
608 }
609 
do_compat_fcntl64(unsigned int fd,unsigned int cmd,compat_ulong_t arg)610 static long do_compat_fcntl64(unsigned int fd, unsigned int cmd,
611 			     compat_ulong_t arg)
612 {
613 	struct fd f = fdget_raw(fd);
614 	struct flock flock;
615 	long err = -EBADF;
616 
617 	if (!f.file)
618 		return err;
619 
620 	if (unlikely(f.file->f_mode & FMODE_PATH)) {
621 		if (!check_fcntl_cmd(cmd))
622 			goto out_put;
623 	}
624 
625 	err = security_file_fcntl(f.file, cmd, arg);
626 	if (err)
627 		goto out_put;
628 
629 	switch (cmd) {
630 	case F_GETLK:
631 		err = get_compat_flock(&flock, compat_ptr(arg));
632 		if (err)
633 			break;
634 		err = fcntl_getlk(f.file, convert_fcntl_cmd(cmd), &flock);
635 		if (err)
636 			break;
637 		err = fixup_compat_flock(&flock);
638 		if (!err)
639 			err = put_compat_flock(&flock, compat_ptr(arg));
640 		break;
641 	case F_GETLK64:
642 	case F_OFD_GETLK:
643 		err = get_compat_flock64(&flock, compat_ptr(arg));
644 		if (err)
645 			break;
646 		err = fcntl_getlk(f.file, convert_fcntl_cmd(cmd), &flock);
647 		if (!err)
648 			err = put_compat_flock64(&flock, compat_ptr(arg));
649 		break;
650 	case F_SETLK:
651 	case F_SETLKW:
652 		err = get_compat_flock(&flock, compat_ptr(arg));
653 		if (err)
654 			break;
655 		err = fcntl_setlk(fd, f.file, convert_fcntl_cmd(cmd), &flock);
656 		break;
657 	case F_SETLK64:
658 	case F_SETLKW64:
659 	case F_OFD_SETLK:
660 	case F_OFD_SETLKW:
661 		err = get_compat_flock64(&flock, compat_ptr(arg));
662 		if (err)
663 			break;
664 		err = fcntl_setlk(fd, f.file, convert_fcntl_cmd(cmd), &flock);
665 		break;
666 	default:
667 		err = do_fcntl(fd, cmd, arg, f.file);
668 		break;
669 	}
670 out_put:
671 	fdput(f);
672 	return err;
673 }
674 
COMPAT_SYSCALL_DEFINE3(fcntl64,unsigned int,fd,unsigned int,cmd,compat_ulong_t,arg)675 COMPAT_SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd,
676 		       compat_ulong_t, arg)
677 {
678 	return do_compat_fcntl64(fd, cmd, arg);
679 }
680 
COMPAT_SYSCALL_DEFINE3(fcntl,unsigned int,fd,unsigned int,cmd,compat_ulong_t,arg)681 COMPAT_SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd,
682 		       compat_ulong_t, arg)
683 {
684 	switch (cmd) {
685 	case F_GETLK64:
686 	case F_SETLK64:
687 	case F_SETLKW64:
688 	case F_OFD_GETLK:
689 	case F_OFD_SETLK:
690 	case F_OFD_SETLKW:
691 		return -EINVAL;
692 	}
693 	return do_compat_fcntl64(fd, cmd, arg);
694 }
695 #endif
696 
697 /* Table to convert sigio signal codes into poll band bitmaps */
698 
699 static const __poll_t band_table[NSIGPOLL] = {
700 	EPOLLIN | EPOLLRDNORM,			/* POLL_IN */
701 	EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND,	/* POLL_OUT */
702 	EPOLLIN | EPOLLRDNORM | EPOLLMSG,		/* POLL_MSG */
703 	EPOLLERR,				/* POLL_ERR */
704 	EPOLLPRI | EPOLLRDBAND,			/* POLL_PRI */
705 	EPOLLHUP | EPOLLERR			/* POLL_HUP */
706 };
707 
sigio_perm(struct task_struct * p,struct fown_struct * fown,int sig)708 static inline int sigio_perm(struct task_struct *p,
709                              struct fown_struct *fown, int sig)
710 {
711 	const struct cred *cred;
712 	int ret;
713 
714 	rcu_read_lock();
715 	cred = __task_cred(p);
716 	ret = ((uid_eq(fown->euid, GLOBAL_ROOT_UID) ||
717 		uid_eq(fown->euid, cred->suid) || uid_eq(fown->euid, cred->uid) ||
718 		uid_eq(fown->uid,  cred->suid) || uid_eq(fown->uid,  cred->uid)) &&
719 	       !security_file_send_sigiotask(p, fown, sig));
720 	rcu_read_unlock();
721 	return ret;
722 }
723 
send_sigio_to_task(struct task_struct * p,struct fown_struct * fown,int fd,int reason,enum pid_type type)724 static void send_sigio_to_task(struct task_struct *p,
725 			       struct fown_struct *fown,
726 			       int fd, int reason, enum pid_type type)
727 {
728 	/*
729 	 * F_SETSIG can change ->signum lockless in parallel, make
730 	 * sure we read it once and use the same value throughout.
731 	 */
732 	int signum = READ_ONCE(fown->signum);
733 
734 	if (!sigio_perm(p, fown, signum))
735 		return;
736 
737 	switch (signum) {
738 		siginfo_t si;
739 		default:
740 			/* Queue a rt signal with the appropriate fd as its
741 			   value.  We use SI_SIGIO as the source, not
742 			   SI_KERNEL, since kernel signals always get
743 			   delivered even if we can't queue.  Failure to
744 			   queue in this case _should_ be reported; we fall
745 			   back to SIGIO in that case. --sct */
746 			clear_siginfo(&si);
747 			si.si_signo = signum;
748 			si.si_errno = 0;
749 		        si.si_code  = reason;
750 			/*
751 			 * Posix definies POLL_IN and friends to be signal
752 			 * specific si_codes for SIG_POLL.  Linux extended
753 			 * these si_codes to other signals in a way that is
754 			 * ambiguous if other signals also have signal
755 			 * specific si_codes.  In that case use SI_SIGIO instead
756 			 * to remove the ambiguity.
757 			 */
758 			if ((signum != SIGPOLL) && sig_specific_sicodes(signum))
759 				si.si_code = SI_SIGIO;
760 
761 			/* Make sure we are called with one of the POLL_*
762 			   reasons, otherwise we could leak kernel stack into
763 			   userspace.  */
764 			BUG_ON((reason < POLL_IN) || ((reason - POLL_IN) >= NSIGPOLL));
765 			if (reason - POLL_IN >= NSIGPOLL)
766 				si.si_band  = ~0L;
767 			else
768 				si.si_band = mangle_poll(band_table[reason - POLL_IN]);
769 			si.si_fd    = fd;
770 			if (!do_send_sig_info(signum, &si, p, type))
771 				break;
772 		/* fall-through: fall back on the old plain SIGIO signal */
773 		case 0:
774 			do_send_sig_info(SIGIO, SEND_SIG_PRIV, p, type);
775 	}
776 }
777 
send_sigio(struct fown_struct * fown,int fd,int band)778 void send_sigio(struct fown_struct *fown, int fd, int band)
779 {
780 	struct task_struct *p;
781 	enum pid_type type;
782 	unsigned long flags;
783 	struct pid *pid;
784 
785 	read_lock_irqsave(&fown->lock, flags);
786 
787 	type = fown->pid_type;
788 	pid = fown->pid;
789 	if (!pid)
790 		goto out_unlock_fown;
791 
792 	if (type <= PIDTYPE_TGID) {
793 		rcu_read_lock();
794 		p = pid_task(pid, PIDTYPE_PID);
795 		if (p)
796 			send_sigio_to_task(p, fown, fd, band, type);
797 		rcu_read_unlock();
798 	} else {
799 		read_lock(&tasklist_lock);
800 		do_each_pid_task(pid, type, p) {
801 			send_sigio_to_task(p, fown, fd, band, type);
802 		} while_each_pid_task(pid, type, p);
803 		read_unlock(&tasklist_lock);
804 	}
805  out_unlock_fown:
806 	read_unlock_irqrestore(&fown->lock, flags);
807 }
808 
send_sigurg_to_task(struct task_struct * p,struct fown_struct * fown,enum pid_type type)809 static void send_sigurg_to_task(struct task_struct *p,
810 				struct fown_struct *fown, enum pid_type type)
811 {
812 	if (sigio_perm(p, fown, SIGURG))
813 		do_send_sig_info(SIGURG, SEND_SIG_PRIV, p, type);
814 }
815 
send_sigurg(struct fown_struct * fown)816 int send_sigurg(struct fown_struct *fown)
817 {
818 	struct task_struct *p;
819 	enum pid_type type;
820 	struct pid *pid;
821 	unsigned long flags;
822 	int ret = 0;
823 
824 	read_lock_irqsave(&fown->lock, flags);
825 
826 	type = fown->pid_type;
827 	pid = fown->pid;
828 	if (!pid)
829 		goto out_unlock_fown;
830 
831 	ret = 1;
832 
833 	if (type <= PIDTYPE_TGID) {
834 		rcu_read_lock();
835 		p = pid_task(pid, PIDTYPE_PID);
836 		if (p)
837 			send_sigurg_to_task(p, fown, type);
838 		rcu_read_unlock();
839 	} else {
840 		read_lock(&tasklist_lock);
841 		do_each_pid_task(pid, type, p) {
842 			send_sigurg_to_task(p, fown, type);
843 		} while_each_pid_task(pid, type, p);
844 		read_unlock(&tasklist_lock);
845 	}
846  out_unlock_fown:
847 	read_unlock_irqrestore(&fown->lock, flags);
848 	return ret;
849 }
850 
851 static DEFINE_SPINLOCK(fasync_lock);
852 static struct kmem_cache *fasync_cache __read_mostly;
853 
fasync_free_rcu(struct rcu_head * head)854 static void fasync_free_rcu(struct rcu_head *head)
855 {
856 	kmem_cache_free(fasync_cache,
857 			container_of(head, struct fasync_struct, fa_rcu));
858 }
859 
860 /*
861  * Remove a fasync entry. If successfully removed, return
862  * positive and clear the FASYNC flag. If no entry exists,
863  * do nothing and return 0.
864  *
865  * NOTE! It is very important that the FASYNC flag always
866  * match the state "is the filp on a fasync list".
867  *
868  */
fasync_remove_entry(struct file * filp,struct fasync_struct ** fapp)869 int fasync_remove_entry(struct file *filp, struct fasync_struct **fapp)
870 {
871 	struct fasync_struct *fa, **fp;
872 	int result = 0;
873 
874 	spin_lock(&filp->f_lock);
875 	spin_lock(&fasync_lock);
876 	for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
877 		if (fa->fa_file != filp)
878 			continue;
879 
880 		write_lock_irq(&fa->fa_lock);
881 		fa->fa_file = NULL;
882 		write_unlock_irq(&fa->fa_lock);
883 
884 		*fp = fa->fa_next;
885 		call_rcu(&fa->fa_rcu, fasync_free_rcu);
886 		filp->f_flags &= ~FASYNC;
887 		result = 1;
888 		break;
889 	}
890 	spin_unlock(&fasync_lock);
891 	spin_unlock(&filp->f_lock);
892 	return result;
893 }
894 
fasync_alloc(void)895 struct fasync_struct *fasync_alloc(void)
896 {
897 	return kmem_cache_alloc(fasync_cache, GFP_KERNEL);
898 }
899 
900 /*
901  * NOTE! This can be used only for unused fasync entries:
902  * entries that actually got inserted on the fasync list
903  * need to be released by rcu - see fasync_remove_entry.
904  */
fasync_free(struct fasync_struct * new)905 void fasync_free(struct fasync_struct *new)
906 {
907 	kmem_cache_free(fasync_cache, new);
908 }
909 
910 /*
911  * Insert a new entry into the fasync list.  Return the pointer to the
912  * old one if we didn't use the new one.
913  *
914  * NOTE! It is very important that the FASYNC flag always
915  * match the state "is the filp on a fasync list".
916  */
fasync_insert_entry(int fd,struct file * filp,struct fasync_struct ** fapp,struct fasync_struct * new)917 struct fasync_struct *fasync_insert_entry(int fd, struct file *filp, struct fasync_struct **fapp, struct fasync_struct *new)
918 {
919         struct fasync_struct *fa, **fp;
920 
921 	spin_lock(&filp->f_lock);
922 	spin_lock(&fasync_lock);
923 	for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
924 		if (fa->fa_file != filp)
925 			continue;
926 
927 		write_lock_irq(&fa->fa_lock);
928 		fa->fa_fd = fd;
929 		write_unlock_irq(&fa->fa_lock);
930 		goto out;
931 	}
932 
933 	rwlock_init(&new->fa_lock);
934 	new->magic = FASYNC_MAGIC;
935 	new->fa_file = filp;
936 	new->fa_fd = fd;
937 	new->fa_next = *fapp;
938 	rcu_assign_pointer(*fapp, new);
939 	filp->f_flags |= FASYNC;
940 
941 out:
942 	spin_unlock(&fasync_lock);
943 	spin_unlock(&filp->f_lock);
944 	return fa;
945 }
946 
947 /*
948  * Add a fasync entry. Return negative on error, positive if
949  * added, and zero if did nothing but change an existing one.
950  */
fasync_add_entry(int fd,struct file * filp,struct fasync_struct ** fapp)951 static int fasync_add_entry(int fd, struct file *filp, struct fasync_struct **fapp)
952 {
953 	struct fasync_struct *new;
954 
955 	new = fasync_alloc();
956 	if (!new)
957 		return -ENOMEM;
958 
959 	/*
960 	 * fasync_insert_entry() returns the old (update) entry if
961 	 * it existed.
962 	 *
963 	 * So free the (unused) new entry and return 0 to let the
964 	 * caller know that we didn't add any new fasync entries.
965 	 */
966 	if (fasync_insert_entry(fd, filp, fapp, new)) {
967 		fasync_free(new);
968 		return 0;
969 	}
970 
971 	return 1;
972 }
973 
974 /*
975  * fasync_helper() is used by almost all character device drivers
976  * to set up the fasync queue, and for regular files by the file
977  * lease code. It returns negative on error, 0 if it did no changes
978  * and positive if it added/deleted the entry.
979  */
fasync_helper(int fd,struct file * filp,int on,struct fasync_struct ** fapp)980 int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp)
981 {
982 	if (!on)
983 		return fasync_remove_entry(filp, fapp);
984 	return fasync_add_entry(fd, filp, fapp);
985 }
986 
987 EXPORT_SYMBOL(fasync_helper);
988 
989 /*
990  * rcu_read_lock() is held
991  */
kill_fasync_rcu(struct fasync_struct * fa,int sig,int band)992 static void kill_fasync_rcu(struct fasync_struct *fa, int sig, int band)
993 {
994 	while (fa) {
995 		struct fown_struct *fown;
996 		unsigned long flags;
997 
998 		if (fa->magic != FASYNC_MAGIC) {
999 			printk(KERN_ERR "kill_fasync: bad magic number in "
1000 			       "fasync_struct!\n");
1001 			return;
1002 		}
1003 		read_lock_irqsave(&fa->fa_lock, flags);
1004 		if (fa->fa_file) {
1005 			fown = &fa->fa_file->f_owner;
1006 			/* Don't send SIGURG to processes which have not set a
1007 			   queued signum: SIGURG has its own default signalling
1008 			   mechanism. */
1009 			if (!(sig == SIGURG && fown->signum == 0))
1010 				send_sigio(fown, fa->fa_fd, band);
1011 		}
1012 		read_unlock_irqrestore(&fa->fa_lock, flags);
1013 		fa = rcu_dereference(fa->fa_next);
1014 	}
1015 }
1016 
kill_fasync(struct fasync_struct ** fp,int sig,int band)1017 void kill_fasync(struct fasync_struct **fp, int sig, int band)
1018 {
1019 	/* First a quick test without locking: usually
1020 	 * the list is empty.
1021 	 */
1022 	if (*fp) {
1023 		rcu_read_lock();
1024 		kill_fasync_rcu(rcu_dereference(*fp), sig, band);
1025 		rcu_read_unlock();
1026 	}
1027 }
1028 EXPORT_SYMBOL(kill_fasync);
1029 
fcntl_init(void)1030 static int __init fcntl_init(void)
1031 {
1032 	/*
1033 	 * Please add new bits here to ensure allocation uniqueness.
1034 	 * Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY
1035 	 * is defined as O_NONBLOCK on some platforms and not on others.
1036 	 */
1037 	BUILD_BUG_ON(21 - 1 /* for O_RDONLY being 0 */ !=
1038 		HWEIGHT32(
1039 			(VALID_OPEN_FLAGS & ~(O_NONBLOCK | O_NDELAY)) |
1040 			__FMODE_EXEC | __FMODE_NONOTIFY));
1041 
1042 	fasync_cache = kmem_cache_create("fasync_cache",
1043 		sizeof(struct fasync_struct), 0, SLAB_PANIC, NULL);
1044 	return 0;
1045 }
1046 
1047 module_init(fcntl_init)
1048