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   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/filelock.h>
  14#include <linux/file.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#include <linux/mount.h>
  29#include <linux/rw_hint.h>
  30
  31#include <linux/poll.h>
  32#include <asm/siginfo.h>
  33#include <linux/uaccess.h>
  34
  35#include "internal.h"
  36
  37#define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT | O_NOATIME)
  38
  39static int setfl(int fd, struct file * filp, unsigned int arg)
  40{
  41	struct inode * inode = file_inode(filp);
  42	int error = 0;
  43
  44	/*
  45	 * O_APPEND cannot be cleared if the file is marked as append-only
  46	 * and the file is open for write.
  47	 */
  48	if (((arg ^ filp->f_flags) & O_APPEND) && IS_APPEND(inode))
  49		return -EPERM;
  50
  51	/* O_NOATIME can only be set by the owner or superuser */
  52	if ((arg & O_NOATIME) && !(filp->f_flags & O_NOATIME))
  53		if (!inode_owner_or_capable(file_mnt_idmap(filp), inode))
  54			return -EPERM;
  55
  56	/* required for strict SunOS emulation */
  57	if (O_NONBLOCK != O_NDELAY)
  58	       if (arg & O_NDELAY)
  59		   arg |= O_NONBLOCK;
  60
  61	/* Pipe packetized mode is controlled by O_DIRECT flag */
  62	if (!S_ISFIFO(inode->i_mode) &&
  63	    (arg & O_DIRECT) &&
  64	    !(filp->f_mode & FMODE_CAN_ODIRECT))
  65		return -EINVAL;
  66
  67	if (filp->f_op->check_flags)
  68		error = filp->f_op->check_flags(arg);
  69	if (error)
  70		return error;
  71
  72	/*
  73	 * ->fasync() is responsible for setting the FASYNC bit.
  74	 */
  75	if (((arg ^ filp->f_flags) & FASYNC) && filp->f_op->fasync) {
  76		error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0);
  77		if (error < 0)
  78			goto out;
  79		if (error > 0)
  80			error = 0;
  81	}
  82	spin_lock(&filp->f_lock);
  83	filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK);
  84	filp->f_iocb_flags = iocb_flags(filp);
  85	spin_unlock(&filp->f_lock);
  86
  87 out:
  88	return error;
  89}
  90
  91/*
  92 * Allocate an file->f_owner struct if it doesn't exist, handling racing
  93 * allocations correctly.
  94 */
  95int file_f_owner_allocate(struct file *file)
  96{
  97	struct fown_struct *f_owner;
  98
  99	f_owner = file_f_owner(file);
 100	if (f_owner)
 101		return 0;
 102
 103	f_owner = kzalloc(sizeof(struct fown_struct), GFP_KERNEL);
 104	if (!f_owner)
 105		return -ENOMEM;
 106
 107	rwlock_init(&f_owner->lock);
 108	f_owner->file = file;
 109	/* If someone else raced us, drop our allocation. */
 110	if (unlikely(cmpxchg(&file->f_owner, NULL, f_owner)))
 111		kfree(f_owner);
 112	return 0;
 113}
 114EXPORT_SYMBOL(file_f_owner_allocate);
 115
 116void file_f_owner_release(struct file *file)
 117{
 118	struct fown_struct *f_owner;
 119
 120	f_owner = file_f_owner(file);
 121	if (f_owner) {
 122		put_pid(f_owner->pid);
 123		kfree(f_owner);
 124	}
 125}
 126
 127void __f_setown(struct file *filp, struct pid *pid, enum pid_type type,
 128		int force)
 129{
 130	struct fown_struct *f_owner;
 131
 132	f_owner = file_f_owner(filp);
 133	if (WARN_ON_ONCE(!f_owner))
 134		return;
 135
 136	write_lock_irq(&f_owner->lock);
 137	if (force || !f_owner->pid) {
 138		put_pid(f_owner->pid);
 139		f_owner->pid = get_pid(pid);
 140		f_owner->pid_type = type;
 141
 142		if (pid) {
 143			const struct cred *cred = current_cred();
 144			security_file_set_fowner(filp);
 145			f_owner->uid = cred->uid;
 146			f_owner->euid = cred->euid;
 147		}
 148	}
 149	write_unlock_irq(&f_owner->lock);
 150}
 151EXPORT_SYMBOL(__f_setown);
 152
 153int f_setown(struct file *filp, int who, int force)
 154{
 155	enum pid_type type;
 156	struct pid *pid = NULL;
 157	int ret = 0;
 158
 159	might_sleep();
 160
 161	type = PIDTYPE_TGID;
 162	if (who < 0) {
 163		/* avoid overflow below */
 164		if (who == INT_MIN)
 165			return -EINVAL;
 166
 167		type = PIDTYPE_PGID;
 168		who = -who;
 169	}
 170
 171	ret = file_f_owner_allocate(filp);
 172	if (ret)
 173		return ret;
 174
 175	rcu_read_lock();
 176	if (who) {
 177		pid = find_vpid(who);
 178		if (!pid)
 179			ret = -ESRCH;
 180	}
 181
 182	if (!ret)
 183		__f_setown(filp, pid, type, force);
 184	rcu_read_unlock();
 185
 186	return ret;
 187}
 188EXPORT_SYMBOL(f_setown);
 189
 190void f_delown(struct file *filp)
 191{
 192	__f_setown(filp, NULL, PIDTYPE_TGID, 1);
 193}
 194
 195pid_t f_getown(struct file *filp)
 196{
 197	pid_t pid = 0;
 198	struct fown_struct *f_owner;
 199
 200	f_owner = file_f_owner(filp);
 201	if (!f_owner)
 202		return pid;
 203
 204	read_lock_irq(&f_owner->lock);
 205	rcu_read_lock();
 206	if (pid_task(f_owner->pid, f_owner->pid_type)) {
 207		pid = pid_vnr(f_owner->pid);
 208		if (f_owner->pid_type == PIDTYPE_PGID)
 209			pid = -pid;
 210	}
 211	rcu_read_unlock();
 212	read_unlock_irq(&f_owner->lock);
 213	return pid;
 214}
 215
 216static int f_setown_ex(struct file *filp, unsigned long arg)
 217{
 218	struct f_owner_ex __user *owner_p = (void __user *)arg;
 219	struct f_owner_ex owner;
 220	struct pid *pid;
 221	int type;
 222	int ret;
 223
 224	ret = copy_from_user(&owner, owner_p, sizeof(owner));
 225	if (ret)
 226		return -EFAULT;
 227
 228	switch (owner.type) {
 229	case F_OWNER_TID:
 230		type = PIDTYPE_PID;
 231		break;
 232
 233	case F_OWNER_PID:
 234		type = PIDTYPE_TGID;
 235		break;
 236
 237	case F_OWNER_PGRP:
 238		type = PIDTYPE_PGID;
 239		break;
 240
 241	default:
 242		return -EINVAL;
 243	}
 244
 245	ret = file_f_owner_allocate(filp);
 246	if (ret)
 247		return ret;
 248
 249	rcu_read_lock();
 250	pid = find_vpid(owner.pid);
 251	if (owner.pid && !pid)
 252		ret = -ESRCH;
 253	else
 254		 __f_setown(filp, pid, type, 1);
 255	rcu_read_unlock();
 256
 257	return ret;
 258}
 259
 260static int f_getown_ex(struct file *filp, unsigned long arg)
 261{
 262	struct f_owner_ex __user *owner_p = (void __user *)arg;
 263	struct f_owner_ex owner = {};
 264	int ret = 0;
 265	struct fown_struct *f_owner;
 266	enum pid_type pid_type = PIDTYPE_PID;
 267
 268	f_owner = file_f_owner(filp);
 269	if (f_owner) {
 270		read_lock_irq(&f_owner->lock);
 271		rcu_read_lock();
 272		if (pid_task(f_owner->pid, f_owner->pid_type))
 273			owner.pid = pid_vnr(f_owner->pid);
 274		rcu_read_unlock();
 275		pid_type = f_owner->pid_type;
 276	}
 277
 278	switch (pid_type) {
 279	case PIDTYPE_PID:
 280		owner.type = F_OWNER_TID;
 281		break;
 282
 283	case PIDTYPE_TGID:
 284		owner.type = F_OWNER_PID;
 285		break;
 286
 287	case PIDTYPE_PGID:
 288		owner.type = F_OWNER_PGRP;
 289		break;
 290
 291	default:
 292		WARN_ON(1);
 293		ret = -EINVAL;
 294		break;
 295	}
 296	if (f_owner)
 297		read_unlock_irq(&f_owner->lock);
 298
 299	if (!ret) {
 300		ret = copy_to_user(owner_p, &owner, sizeof(owner));
 301		if (ret)
 302			ret = -EFAULT;
 303	}
 304	return ret;
 305}
 306
 307#ifdef CONFIG_CHECKPOINT_RESTORE
 308static int f_getowner_uids(struct file *filp, unsigned long arg)
 309{
 310	struct user_namespace *user_ns = current_user_ns();
 311	struct fown_struct *f_owner;
 312	uid_t __user *dst = (void __user *)arg;
 313	uid_t src[2] = {0, 0};
 314	int err;
 315
 316	f_owner = file_f_owner(filp);
 317	if (f_owner) {
 318		read_lock_irq(&f_owner->lock);
 319		src[0] = from_kuid(user_ns, f_owner->uid);
 320		src[1] = from_kuid(user_ns, f_owner->euid);
 321		read_unlock_irq(&f_owner->lock);
 322	}
 323
 324	err  = put_user(src[0], &dst[0]);
 325	err |= put_user(src[1], &dst[1]);
 326
 327	return err;
 328}
 329#else
 330static int f_getowner_uids(struct file *filp, unsigned long arg)
 331{
 332	return -EINVAL;
 333}
 334#endif
 335
 336static bool rw_hint_valid(u64 hint)
 337{
 338	BUILD_BUG_ON(WRITE_LIFE_NOT_SET != RWH_WRITE_LIFE_NOT_SET);
 339	BUILD_BUG_ON(WRITE_LIFE_NONE != RWH_WRITE_LIFE_NONE);
 340	BUILD_BUG_ON(WRITE_LIFE_SHORT != RWH_WRITE_LIFE_SHORT);
 341	BUILD_BUG_ON(WRITE_LIFE_MEDIUM != RWH_WRITE_LIFE_MEDIUM);
 342	BUILD_BUG_ON(WRITE_LIFE_LONG != RWH_WRITE_LIFE_LONG);
 343	BUILD_BUG_ON(WRITE_LIFE_EXTREME != RWH_WRITE_LIFE_EXTREME);
 344
 345	switch (hint) {
 346	case RWH_WRITE_LIFE_NOT_SET:
 347	case RWH_WRITE_LIFE_NONE:
 348	case RWH_WRITE_LIFE_SHORT:
 349	case RWH_WRITE_LIFE_MEDIUM:
 350	case RWH_WRITE_LIFE_LONG:
 351	case RWH_WRITE_LIFE_EXTREME:
 352		return true;
 353	default:
 354		return false;
 355	}
 356}
 357
 358static long fcntl_get_rw_hint(struct file *file, unsigned int cmd,
 359			      unsigned long arg)
 360{
 361	struct inode *inode = file_inode(file);
 362	u64 __user *argp = (u64 __user *)arg;
 363	u64 hint = READ_ONCE(inode->i_write_hint);
 364
 365	if (copy_to_user(argp, &hint, sizeof(*argp)))
 366		return -EFAULT;
 367	return 0;
 368}
 369
 370static long fcntl_set_rw_hint(struct file *file, unsigned int cmd,
 371			      unsigned long arg)
 372{
 373	struct inode *inode = file_inode(file);
 374	u64 __user *argp = (u64 __user *)arg;
 375	u64 hint;
 376
 377	if (!inode_owner_or_capable(file_mnt_idmap(file), inode))
 378		return -EPERM;
 379
 380	if (copy_from_user(&hint, argp, sizeof(hint)))
 381		return -EFAULT;
 382	if (!rw_hint_valid(hint))
 383		return -EINVAL;
 384
 385	WRITE_ONCE(inode->i_write_hint, hint);
 386
 387	/*
 388	 * file->f_mapping->host may differ from inode. As an example,
 389	 * blkdev_open() modifies file->f_mapping.
 390	 */
 391	if (file->f_mapping->host != inode)
 392		WRITE_ONCE(file->f_mapping->host->i_write_hint, hint);
 393
 394	return 0;
 395}
 396
 397/* Is the file descriptor a dup of the file? */
 398static long f_dupfd_query(int fd, struct file *filp)
 399{
 400	CLASS(fd_raw, f)(fd);
 401
 402	if (fd_empty(f))
 403		return -EBADF;
 404
 405	/*
 406	 * We can do the 'fdput()' immediately, as the only thing that
 407	 * matters is the pointer value which isn't changed by the fdput.
 408	 *
 409	 * Technically we didn't need a ref at all, and 'fdget()' was
 410	 * overkill, but given our lockless file pointer lookup, the
 411	 * alternatives are complicated.
 412	 */
 413	return fd_file(f) == filp;
 414}
 415
 416/* Let the caller figure out whether a given file was just created. */
 417static long f_created_query(const struct file *filp)
 418{
 419	return !!(filp->f_mode & FMODE_CREATED);
 420}
 421
 422static int f_owner_sig(struct file *filp, int signum, bool setsig)
 423{
 424	int ret = 0;
 425	struct fown_struct *f_owner;
 426
 427	might_sleep();
 428
 429	if (setsig) {
 430		if (!valid_signal(signum))
 431			return -EINVAL;
 432
 433		ret = file_f_owner_allocate(filp);
 434		if (ret)
 435			return ret;
 436	}
 437
 438	f_owner = file_f_owner(filp);
 439	if (setsig)
 440		f_owner->signum = signum;
 441	else if (f_owner)
 442		ret = f_owner->signum;
 443	return ret;
 444}
 445
 446static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
 447		struct file *filp)
 448{
 449	void __user *argp = (void __user *)arg;
 450	int argi = (int)arg;
 451	struct flock flock;
 452	long err = -EINVAL;
 453
 454	switch (cmd) {
 455	case F_CREATED_QUERY:
 456		err = f_created_query(filp);
 457		break;
 458	case F_DUPFD:
 459		err = f_dupfd(argi, filp, 0);
 460		break;
 461	case F_DUPFD_CLOEXEC:
 462		err = f_dupfd(argi, filp, O_CLOEXEC);
 463		break;
 464	case F_DUPFD_QUERY:
 465		err = f_dupfd_query(argi, filp);
 466		break;
 467	case F_GETFD:
 468		err = get_close_on_exec(fd) ? FD_CLOEXEC : 0;
 469		break;
 470	case F_SETFD:
 471		err = 0;
 472		set_close_on_exec(fd, argi & FD_CLOEXEC);
 473		break;
 474	case F_GETFL:
 475		err = filp->f_flags;
 476		break;
 477	case F_SETFL:
 478		err = setfl(fd, filp, argi);
 479		break;
 480#if BITS_PER_LONG != 32
 481	/* 32-bit arches must use fcntl64() */
 482	case F_OFD_GETLK:
 483#endif
 484	case F_GETLK:
 485		if (copy_from_user(&flock, argp, sizeof(flock)))
 486			return -EFAULT;
 487		err = fcntl_getlk(filp, cmd, &flock);
 488		if (!err && copy_to_user(argp, &flock, sizeof(flock)))
 489			return -EFAULT;
 490		break;
 491#if BITS_PER_LONG != 32
 492	/* 32-bit arches must use fcntl64() */
 493	case F_OFD_SETLK:
 494	case F_OFD_SETLKW:
 495		fallthrough;
 496#endif
 497	case F_SETLK:
 498	case F_SETLKW:
 499		if (copy_from_user(&flock, argp, sizeof(flock)))
 500			return -EFAULT;
 501		err = fcntl_setlk(fd, filp, cmd, &flock);
 502		break;
 503	case F_GETOWN:
 504		/*
 505		 * XXX If f_owner is a process group, the
 506		 * negative return value will get converted
 507		 * into an error.  Oops.  If we keep the
 508		 * current syscall conventions, the only way
 509		 * to fix this will be in libc.
 510		 */
 511		err = f_getown(filp);
 512		force_successful_syscall_return();
 513		break;
 514	case F_SETOWN:
 515		err = f_setown(filp, argi, 1);
 516		break;
 517	case F_GETOWN_EX:
 518		err = f_getown_ex(filp, arg);
 519		break;
 520	case F_SETOWN_EX:
 521		err = f_setown_ex(filp, arg);
 522		break;
 523	case F_GETOWNER_UIDS:
 524		err = f_getowner_uids(filp, arg);
 525		break;
 526	case F_GETSIG:
 527		err = f_owner_sig(filp, 0, false);
 528		break;
 529	case F_SETSIG:
 530		err = f_owner_sig(filp, argi, true);
 531		break;
 532	case F_GETLEASE:
 533		err = fcntl_getlease(filp);
 534		break;
 535	case F_SETLEASE:
 536		err = fcntl_setlease(fd, filp, argi);
 537		break;
 538	case F_NOTIFY:
 539		err = fcntl_dirnotify(fd, filp, argi);
 540		break;
 541	case F_SETPIPE_SZ:
 542	case F_GETPIPE_SZ:
 543		err = pipe_fcntl(filp, cmd, argi);
 544		break;
 545	case F_ADD_SEALS:
 546	case F_GET_SEALS:
 547		err = memfd_fcntl(filp, cmd, argi);
 548		break;
 549	case F_GET_RW_HINT:
 550		err = fcntl_get_rw_hint(filp, cmd, arg);
 551		break;
 552	case F_SET_RW_HINT:
 553		err = fcntl_set_rw_hint(filp, cmd, arg);
 554		break;
 555	default:
 556		break;
 557	}
 558	return err;
 559}
 560
 561static int check_fcntl_cmd(unsigned cmd)
 562{
 563	switch (cmd) {
 564	case F_CREATED_QUERY:
 565	case F_DUPFD:
 566	case F_DUPFD_CLOEXEC:
 567	case F_DUPFD_QUERY:
 568	case F_GETFD:
 569	case F_SETFD:
 570	case F_GETFL:
 571		return 1;
 572	}
 573	return 0;
 574}
 575
 576SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
 577{	
 578	CLASS(fd_raw, f)(fd);
 579	long err;
 580
 581	if (fd_empty(f))
 582		return -EBADF;
 583
 584	if (unlikely(fd_file(f)->f_mode & FMODE_PATH)) {
 585		if (!check_fcntl_cmd(cmd))
 586			return -EBADF;
 587	}
 588
 589	err = security_file_fcntl(fd_file(f), cmd, arg);
 590	if (!err)
 591		err = do_fcntl(fd, cmd, arg, fd_file(f));
 592
 593	return err;
 594}
 595
 596#if BITS_PER_LONG == 32
 597SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd,
 598		unsigned long, arg)
 599{	
 600	void __user *argp = (void __user *)arg;
 601	CLASS(fd_raw, f)(fd);
 602	struct flock64 flock;
 603	long err;
 604
 605	if (fd_empty(f))
 606		return -EBADF;
 607
 608	if (unlikely(fd_file(f)->f_mode & FMODE_PATH)) {
 609		if (!check_fcntl_cmd(cmd))
 610			return -EBADF;
 611	}
 612
 613	err = security_file_fcntl(fd_file(f), cmd, arg);
 614	if (err)
 615		return err;
 616	
 617	switch (cmd) {
 618	case F_GETLK64:
 619	case F_OFD_GETLK:
 620		err = -EFAULT;
 621		if (copy_from_user(&flock, argp, sizeof(flock)))
 622			break;
 623		err = fcntl_getlk64(fd_file(f), cmd, &flock);
 624		if (!err && copy_to_user(argp, &flock, sizeof(flock)))
 625			err = -EFAULT;
 626		break;
 627	case F_SETLK64:
 628	case F_SETLKW64:
 629	case F_OFD_SETLK:
 630	case F_OFD_SETLKW:
 631		err = -EFAULT;
 632		if (copy_from_user(&flock, argp, sizeof(flock)))
 633			break;
 634		err = fcntl_setlk64(fd, fd_file(f), cmd, &flock);
 635		break;
 636	default:
 637		err = do_fcntl(fd, cmd, arg, fd_file(f));
 638		break;
 639	}
 640	return err;
 641}
 642#endif
 643
 644#ifdef CONFIG_COMPAT
 645/* careful - don't use anywhere else */
 646#define copy_flock_fields(dst, src)		\
 647	(dst)->l_type = (src)->l_type;		\
 648	(dst)->l_whence = (src)->l_whence;	\
 649	(dst)->l_start = (src)->l_start;	\
 650	(dst)->l_len = (src)->l_len;		\
 651	(dst)->l_pid = (src)->l_pid;
 652
 653static int get_compat_flock(struct flock *kfl, const struct compat_flock __user *ufl)
 654{
 655	struct compat_flock fl;
 656
 657	if (copy_from_user(&fl, ufl, sizeof(struct compat_flock)))
 658		return -EFAULT;
 659	copy_flock_fields(kfl, &fl);
 660	return 0;
 661}
 662
 663static int get_compat_flock64(struct flock *kfl, const struct compat_flock64 __user *ufl)
 664{
 665	struct compat_flock64 fl;
 666
 667	if (copy_from_user(&fl, ufl, sizeof(struct compat_flock64)))
 668		return -EFAULT;
 669	copy_flock_fields(kfl, &fl);
 670	return 0;
 671}
 672
 673static int put_compat_flock(const struct flock *kfl, struct compat_flock __user *ufl)
 674{
 675	struct compat_flock fl;
 676
 677	memset(&fl, 0, sizeof(struct compat_flock));
 678	copy_flock_fields(&fl, kfl);
 679	if (copy_to_user(ufl, &fl, sizeof(struct compat_flock)))
 680		return -EFAULT;
 681	return 0;
 682}
 683
 684static int put_compat_flock64(const struct flock *kfl, struct compat_flock64 __user *ufl)
 685{
 686	struct compat_flock64 fl;
 687
 688	BUILD_BUG_ON(sizeof(kfl->l_start) > sizeof(ufl->l_start));
 689	BUILD_BUG_ON(sizeof(kfl->l_len) > sizeof(ufl->l_len));
 690
 691	memset(&fl, 0, sizeof(struct compat_flock64));
 692	copy_flock_fields(&fl, kfl);
 693	if (copy_to_user(ufl, &fl, sizeof(struct compat_flock64)))
 694		return -EFAULT;
 695	return 0;
 696}
 697#undef copy_flock_fields
 698
 699static unsigned int
 700convert_fcntl_cmd(unsigned int cmd)
 701{
 702	switch (cmd) {
 703	case F_GETLK64:
 704		return F_GETLK;
 705	case F_SETLK64:
 706		return F_SETLK;
 707	case F_SETLKW64:
 708		return F_SETLKW;
 709	}
 710
 711	return cmd;
 712}
 713
 714/*
 715 * GETLK was successful and we need to return the data, but it needs to fit in
 716 * the compat structure.
 717 * l_start shouldn't be too big, unless the original start + end is greater than
 718 * COMPAT_OFF_T_MAX, in which case the app was asking for trouble, so we return
 719 * -EOVERFLOW in that case.  l_len could be too big, in which case we just
 720 * truncate it, and only allow the app to see that part of the conflicting lock
 721 * that might make sense to it anyway
 722 */
 723static int fixup_compat_flock(struct flock *flock)
 724{
 725	if (flock->l_start > COMPAT_OFF_T_MAX)
 726		return -EOVERFLOW;
 727	if (flock->l_len > COMPAT_OFF_T_MAX)
 728		flock->l_len = COMPAT_OFF_T_MAX;
 729	return 0;
 730}
 731
 732static long do_compat_fcntl64(unsigned int fd, unsigned int cmd,
 733			     compat_ulong_t arg)
 734{
 735	CLASS(fd_raw, f)(fd);
 736	struct flock flock;
 737	long err;
 738
 739	if (fd_empty(f))
 740		return -EBADF;
 741
 742	if (unlikely(fd_file(f)->f_mode & FMODE_PATH)) {
 743		if (!check_fcntl_cmd(cmd))
 744			return -EBADF;
 745	}
 746
 747	err = security_file_fcntl(fd_file(f), cmd, arg);
 748	if (err)
 749		return err;
 750
 751	switch (cmd) {
 752	case F_GETLK:
 753		err = get_compat_flock(&flock, compat_ptr(arg));
 754		if (err)
 755			break;
 756		err = fcntl_getlk(fd_file(f), convert_fcntl_cmd(cmd), &flock);
 757		if (err)
 758			break;
 759		err = fixup_compat_flock(&flock);
 760		if (!err)
 761			err = put_compat_flock(&flock, compat_ptr(arg));
 762		break;
 763	case F_GETLK64:
 764	case F_OFD_GETLK:
 765		err = get_compat_flock64(&flock, compat_ptr(arg));
 766		if (err)
 767			break;
 768		err = fcntl_getlk(fd_file(f), convert_fcntl_cmd(cmd), &flock);
 769		if (!err)
 770			err = put_compat_flock64(&flock, compat_ptr(arg));
 771		break;
 772	case F_SETLK:
 773	case F_SETLKW:
 774		err = get_compat_flock(&flock, compat_ptr(arg));
 775		if (err)
 776			break;
 777		err = fcntl_setlk(fd, fd_file(f), convert_fcntl_cmd(cmd), &flock);
 778		break;
 779	case F_SETLK64:
 780	case F_SETLKW64:
 781	case F_OFD_SETLK:
 782	case F_OFD_SETLKW:
 783		err = get_compat_flock64(&flock, compat_ptr(arg));
 784		if (err)
 785			break;
 786		err = fcntl_setlk(fd, fd_file(f), convert_fcntl_cmd(cmd), &flock);
 787		break;
 788	default:
 789		err = do_fcntl(fd, cmd, arg, fd_file(f));
 790		break;
 791	}
 792	return err;
 793}
 794
 795COMPAT_SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd,
 796		       compat_ulong_t, arg)
 797{
 798	return do_compat_fcntl64(fd, cmd, arg);
 799}
 800
 801COMPAT_SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd,
 802		       compat_ulong_t, arg)
 803{
 804	switch (cmd) {
 805	case F_GETLK64:
 806	case F_SETLK64:
 807	case F_SETLKW64:
 808	case F_OFD_GETLK:
 809	case F_OFD_SETLK:
 810	case F_OFD_SETLKW:
 811		return -EINVAL;
 812	}
 813	return do_compat_fcntl64(fd, cmd, arg);
 814}
 815#endif
 816
 817/* Table to convert sigio signal codes into poll band bitmaps */
 818
 819static const __poll_t band_table[NSIGPOLL] = {
 820	EPOLLIN | EPOLLRDNORM,			/* POLL_IN */
 821	EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND,	/* POLL_OUT */
 822	EPOLLIN | EPOLLRDNORM | EPOLLMSG,		/* POLL_MSG */
 823	EPOLLERR,				/* POLL_ERR */
 824	EPOLLPRI | EPOLLRDBAND,			/* POLL_PRI */
 825	EPOLLHUP | EPOLLERR			/* POLL_HUP */
 826};
 827
 828static inline int sigio_perm(struct task_struct *p,
 829                             struct fown_struct *fown, int sig)
 830{
 831	const struct cred *cred;
 832	int ret;
 833
 834	rcu_read_lock();
 835	cred = __task_cred(p);
 836	ret = ((uid_eq(fown->euid, GLOBAL_ROOT_UID) ||
 837		uid_eq(fown->euid, cred->suid) || uid_eq(fown->euid, cred->uid) ||
 838		uid_eq(fown->uid,  cred->suid) || uid_eq(fown->uid,  cred->uid)) &&
 839	       !security_file_send_sigiotask(p, fown, sig));
 840	rcu_read_unlock();
 841	return ret;
 842}
 843
 844static void send_sigio_to_task(struct task_struct *p,
 845			       struct fown_struct *fown,
 846			       int fd, int reason, enum pid_type type)
 847{
 848	/*
 849	 * F_SETSIG can change ->signum lockless in parallel, make
 850	 * sure we read it once and use the same value throughout.
 851	 */
 852	int signum = READ_ONCE(fown->signum);
 853
 854	if (!sigio_perm(p, fown, signum))
 855		return;
 856
 857	switch (signum) {
 858		default: {
 859			kernel_siginfo_t si;
 860
 861			/* Queue a rt signal with the appropriate fd as its
 862			   value.  We use SI_SIGIO as the source, not 
 863			   SI_KERNEL, since kernel signals always get 
 864			   delivered even if we can't queue.  Failure to
 865			   queue in this case _should_ be reported; we fall
 866			   back to SIGIO in that case. --sct */
 867			clear_siginfo(&si);
 868			si.si_signo = signum;
 869			si.si_errno = 0;
 870		        si.si_code  = reason;
 871			/*
 872			 * Posix definies POLL_IN and friends to be signal
 873			 * specific si_codes for SIG_POLL.  Linux extended
 874			 * these si_codes to other signals in a way that is
 875			 * ambiguous if other signals also have signal
 876			 * specific si_codes.  In that case use SI_SIGIO instead
 877			 * to remove the ambiguity.
 878			 */
 879			if ((signum != SIGPOLL) && sig_specific_sicodes(signum))
 880				si.si_code = SI_SIGIO;
 881
 882			/* Make sure we are called with one of the POLL_*
 883			   reasons, otherwise we could leak kernel stack into
 884			   userspace.  */
 885			BUG_ON((reason < POLL_IN) || ((reason - POLL_IN) >= NSIGPOLL));
 886			if (reason - POLL_IN >= NSIGPOLL)
 887				si.si_band  = ~0L;
 888			else
 889				si.si_band = mangle_poll(band_table[reason - POLL_IN]);
 890			si.si_fd    = fd;
 891			if (!do_send_sig_info(signum, &si, p, type))
 892				break;
 893		}
 894			fallthrough;	/* fall back on the old plain SIGIO signal */
 895		case 0:
 896			do_send_sig_info(SIGIO, SEND_SIG_PRIV, p, type);
 897	}
 898}
 899
 900void send_sigio(struct fown_struct *fown, int fd, int band)
 901{
 902	struct task_struct *p;
 903	enum pid_type type;
 904	unsigned long flags;
 905	struct pid *pid;
 906	
 907	read_lock_irqsave(&fown->lock, flags);
 908
 909	type = fown->pid_type;
 910	pid = fown->pid;
 911	if (!pid)
 912		goto out_unlock_fown;
 913
 914	if (type <= PIDTYPE_TGID) {
 915		rcu_read_lock();
 916		p = pid_task(pid, PIDTYPE_PID);
 917		if (p)
 918			send_sigio_to_task(p, fown, fd, band, type);
 919		rcu_read_unlock();
 920	} else {
 921		read_lock(&tasklist_lock);
 922		do_each_pid_task(pid, type, p) {
 923			send_sigio_to_task(p, fown, fd, band, type);
 924		} while_each_pid_task(pid, type, p);
 925		read_unlock(&tasklist_lock);
 926	}
 927 out_unlock_fown:
 928	read_unlock_irqrestore(&fown->lock, flags);
 929}
 930
 931static void send_sigurg_to_task(struct task_struct *p,
 932				struct fown_struct *fown, enum pid_type type)
 933{
 934	if (sigio_perm(p, fown, SIGURG))
 935		do_send_sig_info(SIGURG, SEND_SIG_PRIV, p, type);
 936}
 937
 938int send_sigurg(struct file *file)
 939{
 940	struct fown_struct *fown;
 941	struct task_struct *p;
 942	enum pid_type type;
 943	struct pid *pid;
 944	unsigned long flags;
 945	int ret = 0;
 946	
 947	fown = file_f_owner(file);
 948	if (!fown)
 949		return 0;
 950
 951	read_lock_irqsave(&fown->lock, flags);
 952
 953	type = fown->pid_type;
 954	pid = fown->pid;
 955	if (!pid)
 956		goto out_unlock_fown;
 957
 958	ret = 1;
 959
 960	if (type <= PIDTYPE_TGID) {
 961		rcu_read_lock();
 962		p = pid_task(pid, PIDTYPE_PID);
 963		if (p)
 964			send_sigurg_to_task(p, fown, type);
 965		rcu_read_unlock();
 966	} else {
 967		read_lock(&tasklist_lock);
 968		do_each_pid_task(pid, type, p) {
 969			send_sigurg_to_task(p, fown, type);
 970		} while_each_pid_task(pid, type, p);
 971		read_unlock(&tasklist_lock);
 972	}
 973 out_unlock_fown:
 974	read_unlock_irqrestore(&fown->lock, flags);
 975	return ret;
 976}
 977
 978static DEFINE_SPINLOCK(fasync_lock);
 979static struct kmem_cache *fasync_cache __ro_after_init;
 980
 981/*
 982 * Remove a fasync entry. If successfully removed, return
 983 * positive and clear the FASYNC flag. If no entry exists,
 984 * do nothing and return 0.
 985 *
 986 * NOTE! It is very important that the FASYNC flag always
 987 * match the state "is the filp on a fasync list".
 988 *
 989 */
 990int fasync_remove_entry(struct file *filp, struct fasync_struct **fapp)
 991{
 992	struct fasync_struct *fa, **fp;
 993	int result = 0;
 994
 995	spin_lock(&filp->f_lock);
 996	spin_lock(&fasync_lock);
 997	for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
 998		if (fa->fa_file != filp)
 999			continue;
1000
1001		write_lock_irq(&fa->fa_lock);
1002		fa->fa_file = NULL;
1003		write_unlock_irq(&fa->fa_lock);
1004
1005		*fp = fa->fa_next;
1006		kfree_rcu(fa, fa_rcu);
1007		filp->f_flags &= ~FASYNC;
1008		result = 1;
1009		break;
1010	}
1011	spin_unlock(&fasync_lock);
1012	spin_unlock(&filp->f_lock);
1013	return result;
1014}
1015
1016struct fasync_struct *fasync_alloc(void)
1017{
1018	return kmem_cache_alloc(fasync_cache, GFP_KERNEL);
1019}
1020
1021/*
1022 * NOTE! This can be used only for unused fasync entries:
1023 * entries that actually got inserted on the fasync list
1024 * need to be released by rcu - see fasync_remove_entry.
1025 */
1026void fasync_free(struct fasync_struct *new)
1027{
1028	kmem_cache_free(fasync_cache, new);
1029}
1030
1031/*
1032 * Insert a new entry into the fasync list.  Return the pointer to the
1033 * old one if we didn't use the new one.
1034 *
1035 * NOTE! It is very important that the FASYNC flag always
1036 * match the state "is the filp on a fasync list".
1037 */
1038struct fasync_struct *fasync_insert_entry(int fd, struct file *filp, struct fasync_struct **fapp, struct fasync_struct *new)
1039{
1040        struct fasync_struct *fa, **fp;
1041
1042	spin_lock(&filp->f_lock);
1043	spin_lock(&fasync_lock);
1044	for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
1045		if (fa->fa_file != filp)
1046			continue;
1047
1048		write_lock_irq(&fa->fa_lock);
1049		fa->fa_fd = fd;
1050		write_unlock_irq(&fa->fa_lock);
1051		goto out;
1052	}
1053
1054	rwlock_init(&new->fa_lock);
1055	new->magic = FASYNC_MAGIC;
1056	new->fa_file = filp;
1057	new->fa_fd = fd;
1058	new->fa_next = *fapp;
1059	rcu_assign_pointer(*fapp, new);
1060	filp->f_flags |= FASYNC;
1061
1062out:
1063	spin_unlock(&fasync_lock);
1064	spin_unlock(&filp->f_lock);
1065	return fa;
1066}
1067
1068/*
1069 * Add a fasync entry. Return negative on error, positive if
1070 * added, and zero if did nothing but change an existing one.
1071 */
1072static int fasync_add_entry(int fd, struct file *filp, struct fasync_struct **fapp)
1073{
1074	struct fasync_struct *new;
1075
1076	new = fasync_alloc();
1077	if (!new)
1078		return -ENOMEM;
1079
1080	/*
1081	 * fasync_insert_entry() returns the old (update) entry if
1082	 * it existed.
1083	 *
1084	 * So free the (unused) new entry and return 0 to let the
1085	 * caller know that we didn't add any new fasync entries.
1086	 */
1087	if (fasync_insert_entry(fd, filp, fapp, new)) {
1088		fasync_free(new);
1089		return 0;
1090	}
1091
1092	return 1;
1093}
1094
1095/*
1096 * fasync_helper() is used by almost all character device drivers
1097 * to set up the fasync queue, and for regular files by the file
1098 * lease code. It returns negative on error, 0 if it did no changes
1099 * and positive if it added/deleted the entry.
1100 */
1101int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp)
1102{
1103	if (!on)
1104		return fasync_remove_entry(filp, fapp);
1105	return fasync_add_entry(fd, filp, fapp);
1106}
1107
1108EXPORT_SYMBOL(fasync_helper);
1109
1110/*
1111 * rcu_read_lock() is held
1112 */
1113static void kill_fasync_rcu(struct fasync_struct *fa, int sig, int band)
1114{
1115	while (fa) {
1116		struct fown_struct *fown;
1117		unsigned long flags;
1118
1119		if (fa->magic != FASYNC_MAGIC) {
1120			printk(KERN_ERR "kill_fasync: bad magic number in "
1121			       "fasync_struct!\n");
1122			return;
1123		}
1124		read_lock_irqsave(&fa->fa_lock, flags);
1125		if (fa->fa_file) {
1126			fown = file_f_owner(fa->fa_file);
1127			if (!fown)
1128				goto next;
1129			/* Don't send SIGURG to processes which have not set a
1130			   queued signum: SIGURG has its own default signalling
1131			   mechanism. */
1132			if (!(sig == SIGURG && fown->signum == 0))
1133				send_sigio(fown, fa->fa_fd, band);
1134		}
1135next:
1136		read_unlock_irqrestore(&fa->fa_lock, flags);
1137		fa = rcu_dereference(fa->fa_next);
1138	}
1139}
1140
1141void kill_fasync(struct fasync_struct **fp, int sig, int band)
1142{
1143	/* First a quick test without locking: usually
1144	 * the list is empty.
1145	 */
1146	if (*fp) {
1147		rcu_read_lock();
1148		kill_fasync_rcu(rcu_dereference(*fp), sig, band);
1149		rcu_read_unlock();
1150	}
1151}
1152EXPORT_SYMBOL(kill_fasync);
1153
1154static int __init fcntl_init(void)
1155{
1156	/*
1157	 * Please add new bits here to ensure allocation uniqueness.
1158	 * Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY
1159	 * is defined as O_NONBLOCK on some platforms and not on others.
1160	 */
1161	BUILD_BUG_ON(21 - 1 /* for O_RDONLY being 0 */ !=
1162		HWEIGHT32(
1163			(VALID_OPEN_FLAGS & ~(O_NONBLOCK | O_NDELAY)) |
1164			__FMODE_EXEC | __FMODE_NONOTIFY));
1165
1166	fasync_cache = kmem_cache_create("fasync_cache",
1167					 sizeof(struct fasync_struct), 0,
1168					 SLAB_PANIC | SLAB_ACCOUNT, NULL);
1169	return 0;
1170}
1171
1172module_init(fcntl_init)