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 39 static 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 */ 95 int 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_obj(struct fown_struct); 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 } 114 EXPORT_SYMBOL(file_f_owner_allocate); 115 116 void 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 } 126 127 void __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 } 151 EXPORT_SYMBOL(__f_setown); 152 153 int 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 } 188 EXPORT_SYMBOL(f_setown); 189 190 void f_delown(struct file *filp) 191 { 192 __f_setown(filp, NULL, PIDTYPE_TGID, 1); 193 } 194 195 pid_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 } 215 216 static 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 } 259 260 static 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 308 static 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 330 static int f_getowner_uids(struct file *filp, unsigned long arg) 331 { 332 return -EINVAL; 333 } 334 #endif 335 336 static 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 } 357 358 static long fcntl_get_rw_hint(struct file *file, unsigned long arg) 359 { 360 struct inode *inode = file_inode(file); 361 u64 __user *argp = (u64 __user *)arg; 362 u64 hint = READ_ONCE(inode->i_write_hint); 363 364 if (copy_to_user(argp, &hint, sizeof(*argp))) 365 return -EFAULT; 366 return 0; 367 } 368 369 static long fcntl_set_rw_hint(struct file *file, unsigned long arg) 370 { 371 struct inode *inode = file_inode(file); 372 u64 __user *argp = (u64 __user *)arg; 373 u64 hint; 374 375 /* nothing is ever written to it */ 376 if (IS_IMMUTABLE(inode)) 377 return -EPERM; 378 if (!inode_owner_or_capable(file_mnt_idmap(file), inode)) 379 return -EPERM; 380 381 if (copy_from_user(&hint, argp, sizeof(hint))) 382 return -EFAULT; 383 if (!rw_hint_valid(hint)) 384 return -EINVAL; 385 386 WRITE_ONCE(inode->i_write_hint, hint); 387 388 /* 389 * file->f_mapping->host may differ from inode. As an example, 390 * blkdev_open() modifies file->f_mapping. 391 */ 392 if (file->f_mapping->host != inode) 393 WRITE_ONCE(file->f_mapping->host->i_write_hint, hint); 394 395 return 0; 396 } 397 398 /* Is the file descriptor a dup of the file? */ 399 static long f_dupfd_query(int fd, struct file *filp) 400 { 401 CLASS(fd_raw, f)(fd); 402 403 if (fd_empty(f)) 404 return -EBADF; 405 406 /* 407 * We can do the 'fdput()' immediately, as the only thing that 408 * matters is the pointer value which isn't changed by the fdput. 409 * 410 * Technically we didn't need a ref at all, and 'fdget()' was 411 * overkill, but given our lockless file pointer lookup, the 412 * alternatives are complicated. 413 */ 414 return fd_file(f) == filp; 415 } 416 417 /* Let the caller figure out whether a given file was just created. */ 418 static long f_created_query(const struct file *filp) 419 { 420 return !!(filp->f_mode & FMODE_CREATED); 421 } 422 423 static int f_owner_sig(struct file *filp, int signum, bool setsig) 424 { 425 int ret = 0; 426 struct fown_struct *f_owner; 427 428 might_sleep(); 429 430 if (setsig) { 431 if (!valid_signal(signum)) 432 return -EINVAL; 433 434 ret = file_f_owner_allocate(filp); 435 if (ret) 436 return ret; 437 } 438 439 f_owner = file_f_owner(filp); 440 if (setsig) 441 f_owner->signum = signum; 442 else if (f_owner) 443 ret = f_owner->signum; 444 return ret; 445 } 446 447 static long do_fcntl(int fd, unsigned int cmd, unsigned long arg, 448 struct file *filp) 449 { 450 void __user *argp = (void __user *)arg; 451 struct delegation deleg; 452 int argi = (int)arg; 453 struct flock flock; 454 long err = -EINVAL; 455 456 switch (cmd) { 457 case F_CREATED_QUERY: 458 err = f_created_query(filp); 459 break; 460 case F_DUPFD: 461 err = f_dupfd(argi, filp, 0); 462 break; 463 case F_DUPFD_CLOEXEC: 464 err = f_dupfd(argi, filp, O_CLOEXEC); 465 break; 466 case F_DUPFD_QUERY: 467 err = f_dupfd_query(argi, filp); 468 break; 469 case F_GETFD: 470 err = get_close_on_exec(fd) ? FD_CLOEXEC : 0; 471 break; 472 case F_SETFD: 473 err = 0; 474 set_close_on_exec(fd, argi & FD_CLOEXEC); 475 break; 476 case F_GETFL: 477 err = filp->f_flags; 478 break; 479 case F_SETFL: 480 err = setfl(fd, filp, argi); 481 break; 482 #if BITS_PER_LONG != 32 483 /* 32-bit arches must use fcntl64() */ 484 case F_OFD_GETLK: 485 #endif 486 case F_GETLK: 487 if (copy_from_user(&flock, argp, sizeof(flock))) 488 return -EFAULT; 489 err = fcntl_getlk(filp, cmd, &flock); 490 if (!err && copy_to_user(argp, &flock, sizeof(flock))) 491 return -EFAULT; 492 break; 493 #if BITS_PER_LONG != 32 494 /* 32-bit arches must use fcntl64() */ 495 case F_OFD_SETLK: 496 case F_OFD_SETLKW: 497 fallthrough; 498 #endif 499 case F_SETLK: 500 case F_SETLKW: 501 if (copy_from_user(&flock, argp, sizeof(flock))) 502 return -EFAULT; 503 err = fcntl_setlk(fd, filp, cmd, &flock); 504 break; 505 case F_GETOWN: 506 /* 507 * XXX If f_owner is a process group, the 508 * negative return value will get converted 509 * into an error. Oops. If we keep the 510 * current syscall conventions, the only way 511 * to fix this will be in libc. 512 */ 513 err = f_getown(filp); 514 force_successful_syscall_return(); 515 break; 516 case F_SETOWN: 517 err = f_setown(filp, argi, 1); 518 break; 519 case F_GETOWN_EX: 520 err = f_getown_ex(filp, arg); 521 break; 522 case F_SETOWN_EX: 523 err = f_setown_ex(filp, arg); 524 break; 525 case F_GETOWNER_UIDS: 526 err = f_getowner_uids(filp, arg); 527 break; 528 case F_GETSIG: 529 err = f_owner_sig(filp, 0, false); 530 break; 531 case F_SETSIG: 532 err = f_owner_sig(filp, argi, true); 533 break; 534 case F_GETLEASE: 535 err = fcntl_getlease(filp); 536 break; 537 case F_SETLEASE: 538 err = fcntl_setlease(fd, filp, argi); 539 break; 540 case F_NOTIFY: 541 err = fcntl_dirnotify(fd, filp, argi); 542 break; 543 case F_SETPIPE_SZ: 544 case F_GETPIPE_SZ: 545 err = pipe_fcntl(filp, cmd, argi); 546 break; 547 case F_ADD_SEALS: 548 case F_GET_SEALS: 549 err = memfd_fcntl(filp, cmd, argi); 550 break; 551 case F_GET_RW_HINT: 552 err = fcntl_get_rw_hint(filp, arg); 553 break; 554 case F_SET_RW_HINT: 555 err = fcntl_set_rw_hint(filp, arg); 556 break; 557 case F_GETDELEG: 558 if (copy_from_user(&deleg, argp, sizeof(deleg))) 559 return -EFAULT; 560 err = fcntl_getdeleg(filp, &deleg); 561 if (!err && copy_to_user(argp, &deleg, sizeof(deleg))) 562 return -EFAULT; 563 break; 564 case F_SETDELEG: 565 if (copy_from_user(&deleg, argp, sizeof(deleg))) 566 return -EFAULT; 567 err = fcntl_setdeleg(fd, filp, &deleg); 568 break; 569 default: 570 break; 571 } 572 return err; 573 } 574 575 static int check_fcntl_cmd(unsigned cmd) 576 { 577 switch (cmd) { 578 case F_CREATED_QUERY: 579 case F_DUPFD: 580 case F_DUPFD_CLOEXEC: 581 case F_DUPFD_QUERY: 582 case F_GETFD: 583 case F_SETFD: 584 case F_GETFL: 585 return 1; 586 } 587 return 0; 588 } 589 590 SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg) 591 { 592 CLASS(fd_raw, f)(fd); 593 long err; 594 595 if (fd_empty(f)) 596 return -EBADF; 597 598 if (unlikely(fd_file(f)->f_mode & FMODE_PATH)) { 599 if (!check_fcntl_cmd(cmd)) 600 return -EBADF; 601 } 602 603 err = security_file_fcntl(fd_file(f), cmd, arg); 604 if (!err) 605 err = do_fcntl(fd, cmd, arg, fd_file(f)); 606 607 return err; 608 } 609 610 #if BITS_PER_LONG == 32 611 SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd, 612 unsigned long, arg) 613 { 614 void __user *argp = (void __user *)arg; 615 CLASS(fd_raw, f)(fd); 616 struct flock64 flock; 617 long err; 618 619 if (fd_empty(f)) 620 return -EBADF; 621 622 if (unlikely(fd_file(f)->f_mode & FMODE_PATH)) { 623 if (!check_fcntl_cmd(cmd)) 624 return -EBADF; 625 } 626 627 err = security_file_fcntl(fd_file(f), cmd, arg); 628 if (err) 629 return err; 630 631 switch (cmd) { 632 case F_GETLK64: 633 case F_OFD_GETLK: 634 err = -EFAULT; 635 if (copy_from_user(&flock, argp, sizeof(flock))) 636 break; 637 err = fcntl_getlk64(fd_file(f), cmd, &flock); 638 if (!err && copy_to_user(argp, &flock, sizeof(flock))) 639 err = -EFAULT; 640 break; 641 case F_SETLK64: 642 case F_SETLKW64: 643 case F_OFD_SETLK: 644 case F_OFD_SETLKW: 645 err = -EFAULT; 646 if (copy_from_user(&flock, argp, sizeof(flock))) 647 break; 648 err = fcntl_setlk64(fd, fd_file(f), cmd, &flock); 649 break; 650 default: 651 err = do_fcntl(fd, cmd, arg, fd_file(f)); 652 break; 653 } 654 return err; 655 } 656 #endif 657 658 #ifdef CONFIG_COMPAT 659 /* careful - don't use anywhere else */ 660 #define copy_flock_fields(dst, src) \ 661 (dst)->l_type = (src)->l_type; \ 662 (dst)->l_whence = (src)->l_whence; \ 663 (dst)->l_start = (src)->l_start; \ 664 (dst)->l_len = (src)->l_len; \ 665 (dst)->l_pid = (src)->l_pid; 666 667 static int get_compat_flock(struct flock *kfl, const struct compat_flock __user *ufl) 668 { 669 struct compat_flock fl; 670 671 if (copy_from_user(&fl, ufl, sizeof(struct compat_flock))) 672 return -EFAULT; 673 copy_flock_fields(kfl, &fl); 674 return 0; 675 } 676 677 static int get_compat_flock64(struct flock *kfl, const struct compat_flock64 __user *ufl) 678 { 679 struct compat_flock64 fl; 680 681 if (copy_from_user(&fl, ufl, sizeof(struct compat_flock64))) 682 return -EFAULT; 683 copy_flock_fields(kfl, &fl); 684 return 0; 685 } 686 687 static int put_compat_flock(const struct flock *kfl, struct compat_flock __user *ufl) 688 { 689 struct compat_flock fl; 690 691 memset(&fl, 0, sizeof(struct compat_flock)); 692 copy_flock_fields(&fl, kfl); 693 if (copy_to_user(ufl, &fl, sizeof(struct compat_flock))) 694 return -EFAULT; 695 return 0; 696 } 697 698 static int put_compat_flock64(const struct flock *kfl, struct compat_flock64 __user *ufl) 699 { 700 struct compat_flock64 fl; 701 702 BUILD_BUG_ON(sizeof(kfl->l_start) > sizeof(ufl->l_start)); 703 BUILD_BUG_ON(sizeof(kfl->l_len) > sizeof(ufl->l_len)); 704 705 memset(&fl, 0, sizeof(struct compat_flock64)); 706 copy_flock_fields(&fl, kfl); 707 if (copy_to_user(ufl, &fl, sizeof(struct compat_flock64))) 708 return -EFAULT; 709 return 0; 710 } 711 #undef copy_flock_fields 712 713 static unsigned int 714 convert_fcntl_cmd(unsigned int cmd) 715 { 716 switch (cmd) { 717 case F_GETLK64: 718 return F_GETLK; 719 case F_SETLK64: 720 return F_SETLK; 721 case F_SETLKW64: 722 return F_SETLKW; 723 } 724 725 return cmd; 726 } 727 728 /* 729 * GETLK was successful and we need to return the data, but it needs to fit in 730 * the compat structure. 731 * l_start shouldn't be too big, unless the original start + end is greater than 732 * COMPAT_OFF_T_MAX, in which case the app was asking for trouble, so we return 733 * -EOVERFLOW in that case. l_len could be too big, in which case we just 734 * truncate it, and only allow the app to see that part of the conflicting lock 735 * that might make sense to it anyway 736 */ 737 static int fixup_compat_flock(struct flock *flock) 738 { 739 if (flock->l_start > COMPAT_OFF_T_MAX) 740 return -EOVERFLOW; 741 if (flock->l_len > COMPAT_OFF_T_MAX) 742 flock->l_len = COMPAT_OFF_T_MAX; 743 return 0; 744 } 745 746 static long do_compat_fcntl64(unsigned int fd, unsigned int cmd, 747 compat_ulong_t arg) 748 { 749 CLASS(fd_raw, f)(fd); 750 struct flock flock; 751 long err; 752 753 if (fd_empty(f)) 754 return -EBADF; 755 756 if (unlikely(fd_file(f)->f_mode & FMODE_PATH)) { 757 if (!check_fcntl_cmd(cmd)) 758 return -EBADF; 759 } 760 761 err = security_file_fcntl(fd_file(f), cmd, arg); 762 if (err) 763 return err; 764 765 switch (cmd) { 766 case F_GETLK: 767 err = get_compat_flock(&flock, compat_ptr(arg)); 768 if (err) 769 break; 770 err = fcntl_getlk(fd_file(f), convert_fcntl_cmd(cmd), &flock); 771 if (err) 772 break; 773 err = fixup_compat_flock(&flock); 774 if (!err) 775 err = put_compat_flock(&flock, compat_ptr(arg)); 776 break; 777 case F_GETLK64: 778 case F_OFD_GETLK: 779 err = get_compat_flock64(&flock, compat_ptr(arg)); 780 if (err) 781 break; 782 err = fcntl_getlk(fd_file(f), convert_fcntl_cmd(cmd), &flock); 783 if (!err) 784 err = put_compat_flock64(&flock, compat_ptr(arg)); 785 break; 786 case F_SETLK: 787 case F_SETLKW: 788 err = get_compat_flock(&flock, compat_ptr(arg)); 789 if (err) 790 break; 791 err = fcntl_setlk(fd, fd_file(f), convert_fcntl_cmd(cmd), &flock); 792 break; 793 case F_SETLK64: 794 case F_SETLKW64: 795 case F_OFD_SETLK: 796 case F_OFD_SETLKW: 797 err = get_compat_flock64(&flock, compat_ptr(arg)); 798 if (err) 799 break; 800 err = fcntl_setlk(fd, fd_file(f), convert_fcntl_cmd(cmd), &flock); 801 break; 802 default: 803 err = do_fcntl(fd, cmd, arg, fd_file(f)); 804 break; 805 } 806 return err; 807 } 808 809 COMPAT_SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd, 810 compat_ulong_t, arg) 811 { 812 return do_compat_fcntl64(fd, cmd, arg); 813 } 814 815 COMPAT_SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, 816 compat_ulong_t, arg) 817 { 818 switch (cmd) { 819 case F_GETLK64: 820 case F_SETLK64: 821 case F_SETLKW64: 822 case F_OFD_GETLK: 823 case F_OFD_SETLK: 824 case F_OFD_SETLKW: 825 return -EINVAL; 826 } 827 return do_compat_fcntl64(fd, cmd, arg); 828 } 829 #endif 830 831 /* Table to convert sigio signal codes into poll band bitmaps */ 832 833 static const __poll_t band_table[NSIGPOLL] = { 834 EPOLLIN | EPOLLRDNORM, /* POLL_IN */ 835 EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND, /* POLL_OUT */ 836 EPOLLIN | EPOLLRDNORM | EPOLLMSG, /* POLL_MSG */ 837 EPOLLERR, /* POLL_ERR */ 838 EPOLLPRI | EPOLLRDBAND, /* POLL_PRI */ 839 EPOLLHUP | EPOLLERR /* POLL_HUP */ 840 }; 841 842 static inline int sigio_perm(struct task_struct *p, 843 struct fown_struct *fown, int sig) 844 { 845 const struct cred *cred; 846 int ret; 847 848 rcu_read_lock(); 849 cred = __task_cred(p); 850 ret = ((uid_eq(fown->euid, GLOBAL_ROOT_UID) || 851 uid_eq(fown->euid, cred->suid) || uid_eq(fown->euid, cred->uid) || 852 uid_eq(fown->uid, cred->suid) || uid_eq(fown->uid, cred->uid)) && 853 !security_file_send_sigiotask(p, fown, sig)); 854 rcu_read_unlock(); 855 return ret; 856 } 857 858 static void send_sigio_to_task(struct task_struct *p, 859 struct fown_struct *fown, 860 int fd, int reason, enum pid_type type) 861 { 862 /* 863 * F_SETSIG can change ->signum lockless in parallel, make 864 * sure we read it once and use the same value throughout. 865 */ 866 int signum = READ_ONCE(fown->signum); 867 868 if (!sigio_perm(p, fown, signum)) 869 return; 870 871 switch (signum) { 872 default: { 873 kernel_siginfo_t si; 874 875 /* Queue a rt signal with the appropriate fd as its 876 value. We use SI_SIGIO as the source, not 877 SI_KERNEL, since kernel signals always get 878 delivered even if we can't queue. Failure to 879 queue in this case _should_ be reported; we fall 880 back to SIGIO in that case. --sct */ 881 clear_siginfo(&si); 882 si.si_signo = signum; 883 si.si_errno = 0; 884 si.si_code = reason; 885 /* 886 * Posix definies POLL_IN and friends to be signal 887 * specific si_codes for SIG_POLL. Linux extended 888 * these si_codes to other signals in a way that is 889 * ambiguous if other signals also have signal 890 * specific si_codes. In that case use SI_SIGIO instead 891 * to remove the ambiguity. 892 */ 893 if ((signum != SIGPOLL) && sig_specific_sicodes(signum)) 894 si.si_code = SI_SIGIO; 895 896 /* Make sure we are called with one of the POLL_* 897 reasons, otherwise we could leak kernel stack into 898 userspace. */ 899 BUG_ON((reason < POLL_IN) || ((reason - POLL_IN) >= NSIGPOLL)); 900 if (reason - POLL_IN >= NSIGPOLL) 901 si.si_band = ~0L; 902 else 903 si.si_band = mangle_poll(band_table[reason - POLL_IN]); 904 si.si_fd = fd; 905 if (!do_send_sig_info(signum, &si, p, type)) 906 break; 907 } 908 fallthrough; /* fall back on the old plain SIGIO signal */ 909 case 0: 910 do_send_sig_info(SIGIO, SEND_SIG_PRIV, p, type); 911 } 912 } 913 914 void send_sigio(struct fown_struct *fown, int fd, int band) 915 { 916 struct task_struct *p; 917 enum pid_type type; 918 unsigned long flags; 919 struct pid *pid; 920 921 read_lock_irqsave(&fown->lock, flags); 922 923 type = fown->pid_type; 924 pid = fown->pid; 925 if (!pid) 926 goto out_unlock_fown; 927 928 if (type <= PIDTYPE_TGID) { 929 rcu_read_lock(); 930 p = pid_task(pid, PIDTYPE_PID); 931 if (p) 932 send_sigio_to_task(p, fown, fd, band, type); 933 rcu_read_unlock(); 934 } else { 935 rcu_read_lock(); 936 do_each_pid_task(pid, type, p) { 937 send_sigio_to_task(p, fown, fd, band, type); 938 } while_each_pid_task(pid, type, p); 939 rcu_read_unlock(); 940 } 941 out_unlock_fown: 942 read_unlock_irqrestore(&fown->lock, flags); 943 } 944 945 static void send_sigurg_to_task(struct task_struct *p, 946 struct fown_struct *fown, enum pid_type type) 947 { 948 if (sigio_perm(p, fown, SIGURG)) 949 do_send_sig_info(SIGURG, SEND_SIG_PRIV, p, type); 950 } 951 952 int send_sigurg(struct file *file) 953 { 954 struct fown_struct *fown; 955 struct task_struct *p; 956 enum pid_type type; 957 struct pid *pid; 958 unsigned long flags; 959 int ret = 0; 960 961 fown = file_f_owner(file); 962 if (!fown) 963 return 0; 964 965 read_lock_irqsave(&fown->lock, flags); 966 967 type = fown->pid_type; 968 pid = fown->pid; 969 if (!pid) 970 goto out_unlock_fown; 971 972 ret = 1; 973 974 if (type <= PIDTYPE_TGID) { 975 rcu_read_lock(); 976 p = pid_task(pid, PIDTYPE_PID); 977 if (p) 978 send_sigurg_to_task(p, fown, type); 979 rcu_read_unlock(); 980 } else { 981 rcu_read_lock(); 982 do_each_pid_task(pid, type, p) { 983 send_sigurg_to_task(p, fown, type); 984 } while_each_pid_task(pid, type, p); 985 rcu_read_unlock(); 986 } 987 out_unlock_fown: 988 read_unlock_irqrestore(&fown->lock, flags); 989 return ret; 990 } 991 992 static DEFINE_SPINLOCK(fasync_lock); 993 static struct kmem_cache *fasync_cache __ro_after_init; 994 995 /* 996 * Remove a fasync entry. If successfully removed, return 997 * positive and clear the FASYNC flag. If no entry exists, 998 * do nothing and return 0. 999 * 1000 * NOTE! It is very important that the FASYNC flag always 1001 * match the state "is the filp on a fasync list". 1002 * 1003 */ 1004 int fasync_remove_entry(struct file *filp, struct fasync_struct **fapp) 1005 { 1006 struct fasync_struct *fa, **fp; 1007 int result = 0; 1008 1009 spin_lock(&filp->f_lock); 1010 spin_lock(&fasync_lock); 1011 for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) { 1012 if (fa->fa_file != filp) 1013 continue; 1014 1015 write_lock_irq(&fa->fa_lock); 1016 fa->fa_file = NULL; 1017 write_unlock_irq(&fa->fa_lock); 1018 1019 *fp = fa->fa_next; 1020 kfree_rcu(fa, fa_rcu); 1021 filp->f_flags &= ~FASYNC; 1022 result = 1; 1023 break; 1024 } 1025 spin_unlock(&fasync_lock); 1026 spin_unlock(&filp->f_lock); 1027 return result; 1028 } 1029 1030 struct fasync_struct *fasync_alloc(void) 1031 { 1032 return kmem_cache_alloc(fasync_cache, GFP_KERNEL); 1033 } 1034 1035 /* 1036 * NOTE! This can be used only for unused fasync entries: 1037 * entries that actually got inserted on the fasync list 1038 * need to be released by rcu - see fasync_remove_entry. 1039 */ 1040 void fasync_free(struct fasync_struct *new) 1041 { 1042 kmem_cache_free(fasync_cache, new); 1043 } 1044 1045 /* 1046 * Insert a new entry into the fasync list. Return the pointer to the 1047 * old one if we didn't use the new one. 1048 * 1049 * NOTE! It is very important that the FASYNC flag always 1050 * match the state "is the filp on a fasync list". 1051 */ 1052 struct fasync_struct *fasync_insert_entry(int fd, struct file *filp, struct fasync_struct **fapp, struct fasync_struct *new) 1053 { 1054 struct fasync_struct *fa, **fp; 1055 1056 spin_lock(&filp->f_lock); 1057 spin_lock(&fasync_lock); 1058 for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) { 1059 if (fa->fa_file != filp) 1060 continue; 1061 1062 write_lock_irq(&fa->fa_lock); 1063 fa->fa_fd = fd; 1064 write_unlock_irq(&fa->fa_lock); 1065 goto out; 1066 } 1067 1068 rwlock_init(&new->fa_lock); 1069 new->magic = FASYNC_MAGIC; 1070 new->fa_file = filp; 1071 new->fa_fd = fd; 1072 new->fa_next = *fapp; 1073 rcu_assign_pointer(*fapp, new); 1074 filp->f_flags |= FASYNC; 1075 1076 out: 1077 spin_unlock(&fasync_lock); 1078 spin_unlock(&filp->f_lock); 1079 return fa; 1080 } 1081 1082 /* 1083 * Add a fasync entry. Return negative on error, positive if 1084 * added, and zero if did nothing but change an existing one. 1085 */ 1086 static int fasync_add_entry(int fd, struct file *filp, struct fasync_struct **fapp) 1087 { 1088 struct fasync_struct *new; 1089 1090 new = fasync_alloc(); 1091 if (!new) 1092 return -ENOMEM; 1093 1094 /* 1095 * fasync_insert_entry() returns the old (update) entry if 1096 * it existed. 1097 * 1098 * So free the (unused) new entry and return 0 to let the 1099 * caller know that we didn't add any new fasync entries. 1100 */ 1101 if (fasync_insert_entry(fd, filp, fapp, new)) { 1102 fasync_free(new); 1103 return 0; 1104 } 1105 1106 return 1; 1107 } 1108 1109 /* 1110 * fasync_helper() is used by almost all character device drivers 1111 * to set up the fasync queue, and for regular files by the file 1112 * lease code. It returns negative on error, 0 if it did no changes 1113 * and positive if it added/deleted the entry. 1114 */ 1115 int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp) 1116 { 1117 if (!on) 1118 return fasync_remove_entry(filp, fapp); 1119 return fasync_add_entry(fd, filp, fapp); 1120 } 1121 1122 EXPORT_SYMBOL(fasync_helper); 1123 1124 /* 1125 * rcu_read_lock() is held 1126 */ 1127 static void kill_fasync_rcu(struct fasync_struct *fa, int sig, int band) 1128 { 1129 while (fa) { 1130 struct fown_struct *fown; 1131 unsigned long flags; 1132 1133 if (fa->magic != FASYNC_MAGIC) { 1134 printk(KERN_ERR "kill_fasync: bad magic number in " 1135 "fasync_struct!\n"); 1136 return; 1137 } 1138 read_lock_irqsave(&fa->fa_lock, flags); 1139 if (fa->fa_file) { 1140 fown = file_f_owner(fa->fa_file); 1141 if (!fown) 1142 goto next; 1143 /* Don't send SIGURG to processes which have not set a 1144 queued signum: SIGURG has its own default signalling 1145 mechanism. */ 1146 if (!(sig == SIGURG && fown->signum == 0)) 1147 send_sigio(fown, fa->fa_fd, band); 1148 } 1149 next: 1150 read_unlock_irqrestore(&fa->fa_lock, flags); 1151 fa = rcu_dereference(fa->fa_next); 1152 } 1153 } 1154 1155 void kill_fasync(struct fasync_struct **fp, int sig, int band) 1156 { 1157 /* First a quick test without locking: usually 1158 * the list is empty. 1159 */ 1160 if (*fp) { 1161 rcu_read_lock(); 1162 kill_fasync_rcu(rcu_dereference(*fp), sig, band); 1163 rcu_read_unlock(); 1164 } 1165 } 1166 EXPORT_SYMBOL(kill_fasync); 1167 1168 static int __init fcntl_init(void) 1169 { 1170 /* 1171 * Please add new bits here to ensure allocation uniqueness. 1172 * Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY 1173 * is defined as O_NONBLOCK on some platforms and not on others. 1174 */ 1175 BUILD_BUG_ON(22 - 1 /* for O_RDONLY being 0 */ != 1176 HWEIGHT32( 1177 (VALID_OPEN_FLAGS & ~(O_NONBLOCK | O_NDELAY)) | 1178 __FMODE_EXEC | __O_REGULAR)); 1179 1180 fasync_cache = kmem_cache_create("fasync_cache", 1181 sizeof(struct fasync_struct), 0, 1182 SLAB_PANIC | SLAB_ACCOUNT, NULL); 1183 return 0; 1184 } 1185 1186 module_init(fcntl_init) 1187