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/fdtable.h> 16 #include <linux/capability.h> 17 #include <linux/dnotify.h> 18 #include <linux/slab.h> 19 #include <linux/module.h> 20 #include <linux/pipe_fs_i.h> 21 #include <linux/security.h> 22 #include <linux/ptrace.h> 23 #include <linux/signal.h> 24 #include <linux/rcupdate.h> 25 #include <linux/pid_namespace.h> 26 #include <linux/user_namespace.h> 27 #include <linux/memfd.h> 28 #include <linux/compat.h> 29 #include <linux/mount.h> 30 #include <linux/rw_hint.h> 31 32 #include <linux/poll.h> 33 #include <asm/siginfo.h> 34 #include <linux/uaccess.h> 35 36 #include "internal.h" 37 38 #define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT | O_NOATIME) 39 40 static int setfl(int fd, struct file * filp, unsigned int arg) 41 { 42 struct inode * inode = file_inode(filp); 43 int error = 0; 44 45 /* 46 * O_APPEND cannot be cleared if the file is marked as append-only 47 * and the file is open for write. 48 */ 49 if (((arg ^ filp->f_flags) & O_APPEND) && IS_APPEND(inode)) 50 return -EPERM; 51 52 /* O_NOATIME can only be set by the owner or superuser */ 53 if ((arg & O_NOATIME) && !(filp->f_flags & O_NOATIME)) 54 if (!inode_owner_or_capable(file_mnt_idmap(filp), inode)) 55 return -EPERM; 56 57 /* required for strict SunOS emulation */ 58 if (O_NONBLOCK != O_NDELAY) 59 if (arg & O_NDELAY) 60 arg |= O_NONBLOCK; 61 62 /* Pipe packetized mode is controlled by O_DIRECT flag */ 63 if (!S_ISFIFO(inode->i_mode) && 64 (arg & O_DIRECT) && 65 !(filp->f_mode & FMODE_CAN_ODIRECT)) 66 return -EINVAL; 67 68 if (filp->f_op->check_flags) 69 error = filp->f_op->check_flags(arg); 70 if (error) 71 return error; 72 73 /* 74 * ->fasync() is responsible for setting the FASYNC bit. 75 */ 76 if (((arg ^ filp->f_flags) & FASYNC) && filp->f_op->fasync) { 77 error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0); 78 if (error < 0) 79 goto out; 80 if (error > 0) 81 error = 0; 82 } 83 spin_lock(&filp->f_lock); 84 filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK); 85 filp->f_iocb_flags = iocb_flags(filp); 86 spin_unlock(&filp->f_lock); 87 88 out: 89 return error; 90 } 91 92 /* 93 * Allocate an file->f_owner struct if it doesn't exist, handling racing 94 * allocations correctly. 95 */ 96 int file_f_owner_allocate(struct file *file) 97 { 98 struct fown_struct *f_owner; 99 100 f_owner = file_f_owner(file); 101 if (f_owner) 102 return 0; 103 104 f_owner = kzalloc(sizeof(struct fown_struct), GFP_KERNEL); 105 if (!f_owner) 106 return -ENOMEM; 107 108 rwlock_init(&f_owner->lock); 109 f_owner->file = file; 110 /* If someone else raced us, drop our allocation. */ 111 if (unlikely(cmpxchg(&file->f_owner, NULL, f_owner))) 112 kfree(f_owner); 113 return 0; 114 } 115 EXPORT_SYMBOL(file_f_owner_allocate); 116 117 void file_f_owner_release(struct file *file) 118 { 119 struct fown_struct *f_owner; 120 121 f_owner = file_f_owner(file); 122 if (f_owner) { 123 put_pid(f_owner->pid); 124 kfree(f_owner); 125 } 126 } 127 128 void __f_setown(struct file *filp, struct pid *pid, enum pid_type type, 129 int force) 130 { 131 struct fown_struct *f_owner; 132 133 f_owner = file_f_owner(filp); 134 if (WARN_ON_ONCE(!f_owner)) 135 return; 136 137 write_lock_irq(&f_owner->lock); 138 if (force || !f_owner->pid) { 139 put_pid(f_owner->pid); 140 f_owner->pid = get_pid(pid); 141 f_owner->pid_type = type; 142 143 if (pid) { 144 const struct cred *cred = current_cred(); 145 security_file_set_fowner(filp); 146 f_owner->uid = cred->uid; 147 f_owner->euid = cred->euid; 148 } 149 } 150 write_unlock_irq(&f_owner->lock); 151 } 152 EXPORT_SYMBOL(__f_setown); 153 154 int f_setown(struct file *filp, int who, int force) 155 { 156 enum pid_type type; 157 struct pid *pid = NULL; 158 int ret = 0; 159 160 might_sleep(); 161 162 type = PIDTYPE_TGID; 163 if (who < 0) { 164 /* avoid overflow below */ 165 if (who == INT_MIN) 166 return -EINVAL; 167 168 type = PIDTYPE_PGID; 169 who = -who; 170 } 171 172 ret = file_f_owner_allocate(filp); 173 if (ret) 174 return ret; 175 176 rcu_read_lock(); 177 if (who) { 178 pid = find_vpid(who); 179 if (!pid) 180 ret = -ESRCH; 181 } 182 183 if (!ret) 184 __f_setown(filp, pid, type, force); 185 rcu_read_unlock(); 186 187 return ret; 188 } 189 EXPORT_SYMBOL(f_setown); 190 191 void f_delown(struct file *filp) 192 { 193 __f_setown(filp, NULL, PIDTYPE_TGID, 1); 194 } 195 196 pid_t f_getown(struct file *filp) 197 { 198 pid_t pid = 0; 199 struct fown_struct *f_owner; 200 201 f_owner = file_f_owner(filp); 202 if (!f_owner) 203 return pid; 204 205 read_lock_irq(&f_owner->lock); 206 rcu_read_lock(); 207 if (pid_task(f_owner->pid, f_owner->pid_type)) { 208 pid = pid_vnr(f_owner->pid); 209 if (f_owner->pid_type == PIDTYPE_PGID) 210 pid = -pid; 211 } 212 rcu_read_unlock(); 213 read_unlock_irq(&f_owner->lock); 214 return pid; 215 } 216 217 static int f_setown_ex(struct file *filp, unsigned long arg) 218 { 219 struct f_owner_ex __user *owner_p = (void __user *)arg; 220 struct f_owner_ex owner; 221 struct pid *pid; 222 int type; 223 int ret; 224 225 ret = copy_from_user(&owner, owner_p, sizeof(owner)); 226 if (ret) 227 return -EFAULT; 228 229 switch (owner.type) { 230 case F_OWNER_TID: 231 type = PIDTYPE_PID; 232 break; 233 234 case F_OWNER_PID: 235 type = PIDTYPE_TGID; 236 break; 237 238 case F_OWNER_PGRP: 239 type = PIDTYPE_PGID; 240 break; 241 242 default: 243 return -EINVAL; 244 } 245 246 ret = file_f_owner_allocate(filp); 247 if (ret) 248 return ret; 249 250 rcu_read_lock(); 251 pid = find_vpid(owner.pid); 252 if (owner.pid && !pid) 253 ret = -ESRCH; 254 else 255 __f_setown(filp, pid, type, 1); 256 rcu_read_unlock(); 257 258 return ret; 259 } 260 261 static int f_getown_ex(struct file *filp, unsigned long arg) 262 { 263 struct f_owner_ex __user *owner_p = (void __user *)arg; 264 struct f_owner_ex owner = {}; 265 int ret = 0; 266 struct fown_struct *f_owner; 267 enum pid_type pid_type = PIDTYPE_PID; 268 269 f_owner = file_f_owner(filp); 270 if (f_owner) { 271 read_lock_irq(&f_owner->lock); 272 rcu_read_lock(); 273 if (pid_task(f_owner->pid, f_owner->pid_type)) 274 owner.pid = pid_vnr(f_owner->pid); 275 rcu_read_unlock(); 276 pid_type = f_owner->pid_type; 277 } 278 279 switch (pid_type) { 280 case PIDTYPE_PID: 281 owner.type = F_OWNER_TID; 282 break; 283 284 case PIDTYPE_TGID: 285 owner.type = F_OWNER_PID; 286 break; 287 288 case PIDTYPE_PGID: 289 owner.type = F_OWNER_PGRP; 290 break; 291 292 default: 293 WARN_ON(1); 294 ret = -EINVAL; 295 break; 296 } 297 if (f_owner) 298 read_unlock_irq(&f_owner->lock); 299 300 if (!ret) { 301 ret = copy_to_user(owner_p, &owner, sizeof(owner)); 302 if (ret) 303 ret = -EFAULT; 304 } 305 return ret; 306 } 307 308 #ifdef CONFIG_CHECKPOINT_RESTORE 309 static int f_getowner_uids(struct file *filp, unsigned long arg) 310 { 311 struct user_namespace *user_ns = current_user_ns(); 312 struct fown_struct *f_owner; 313 uid_t __user *dst = (void __user *)arg; 314 uid_t src[2] = {0, 0}; 315 int err; 316 317 f_owner = file_f_owner(filp); 318 if (f_owner) { 319 read_lock_irq(&f_owner->lock); 320 src[0] = from_kuid(user_ns, f_owner->uid); 321 src[1] = from_kuid(user_ns, f_owner->euid); 322 read_unlock_irq(&f_owner->lock); 323 } 324 325 err = put_user(src[0], &dst[0]); 326 err |= put_user(src[1], &dst[1]); 327 328 return err; 329 } 330 #else 331 static int f_getowner_uids(struct file *filp, unsigned long arg) 332 { 333 return -EINVAL; 334 } 335 #endif 336 337 static bool rw_hint_valid(u64 hint) 338 { 339 BUILD_BUG_ON(WRITE_LIFE_NOT_SET != RWH_WRITE_LIFE_NOT_SET); 340 BUILD_BUG_ON(WRITE_LIFE_NONE != RWH_WRITE_LIFE_NONE); 341 BUILD_BUG_ON(WRITE_LIFE_SHORT != RWH_WRITE_LIFE_SHORT); 342 BUILD_BUG_ON(WRITE_LIFE_MEDIUM != RWH_WRITE_LIFE_MEDIUM); 343 BUILD_BUG_ON(WRITE_LIFE_LONG != RWH_WRITE_LIFE_LONG); 344 BUILD_BUG_ON(WRITE_LIFE_EXTREME != RWH_WRITE_LIFE_EXTREME); 345 346 switch (hint) { 347 case RWH_WRITE_LIFE_NOT_SET: 348 case RWH_WRITE_LIFE_NONE: 349 case RWH_WRITE_LIFE_SHORT: 350 case RWH_WRITE_LIFE_MEDIUM: 351 case RWH_WRITE_LIFE_LONG: 352 case RWH_WRITE_LIFE_EXTREME: 353 return true; 354 default: 355 return false; 356 } 357 } 358 359 static long fcntl_get_rw_hint(struct file *file, unsigned int cmd, 360 unsigned long arg) 361 { 362 struct inode *inode = file_inode(file); 363 u64 __user *argp = (u64 __user *)arg; 364 u64 hint = READ_ONCE(inode->i_write_hint); 365 366 if (copy_to_user(argp, &hint, sizeof(*argp))) 367 return -EFAULT; 368 return 0; 369 } 370 371 static long fcntl_set_rw_hint(struct file *file, unsigned int cmd, 372 unsigned long arg) 373 { 374 struct inode *inode = file_inode(file); 375 u64 __user *argp = (u64 __user *)arg; 376 u64 hint; 377 378 if (copy_from_user(&hint, argp, sizeof(hint))) 379 return -EFAULT; 380 if (!rw_hint_valid(hint)) 381 return -EINVAL; 382 383 WRITE_ONCE(inode->i_write_hint, hint); 384 385 /* 386 * file->f_mapping->host may differ from inode. As an example, 387 * blkdev_open() modifies file->f_mapping. 388 */ 389 if (file->f_mapping->host != inode) 390 WRITE_ONCE(file->f_mapping->host->i_write_hint, hint); 391 392 return 0; 393 } 394 395 /* Is the file descriptor a dup of the file? */ 396 static long f_dupfd_query(int fd, struct file *filp) 397 { 398 CLASS(fd_raw, f)(fd); 399 400 /* 401 * We can do the 'fdput()' immediately, as the only thing that 402 * matters is the pointer value which isn't changed by the fdput. 403 * 404 * Technically we didn't need a ref at all, and 'fdget()' was 405 * overkill, but given our lockless file pointer lookup, the 406 * alternatives are complicated. 407 */ 408 return fd_file(f) == filp; 409 } 410 411 /* Let the caller figure out whether a given file was just created. */ 412 static long f_created_query(const struct file *filp) 413 { 414 return !!(filp->f_mode & FMODE_CREATED); 415 } 416 417 static int f_owner_sig(struct file *filp, int signum, bool setsig) 418 { 419 int ret = 0; 420 struct fown_struct *f_owner; 421 422 might_sleep(); 423 424 if (setsig) { 425 if (!valid_signal(signum)) 426 return -EINVAL; 427 428 ret = file_f_owner_allocate(filp); 429 if (ret) 430 return ret; 431 } 432 433 f_owner = file_f_owner(filp); 434 if (setsig) 435 f_owner->signum = signum; 436 else if (f_owner) 437 ret = f_owner->signum; 438 return ret; 439 } 440 441 static long do_fcntl(int fd, unsigned int cmd, unsigned long arg, 442 struct file *filp) 443 { 444 void __user *argp = (void __user *)arg; 445 int argi = (int)arg; 446 struct flock flock; 447 long err = -EINVAL; 448 449 switch (cmd) { 450 case F_CREATED_QUERY: 451 err = f_created_query(filp); 452 break; 453 case F_DUPFD: 454 err = f_dupfd(argi, filp, 0); 455 break; 456 case F_DUPFD_CLOEXEC: 457 err = f_dupfd(argi, filp, O_CLOEXEC); 458 break; 459 case F_DUPFD_QUERY: 460 err = f_dupfd_query(argi, filp); 461 break; 462 case F_GETFD: 463 err = get_close_on_exec(fd) ? FD_CLOEXEC : 0; 464 break; 465 case F_SETFD: 466 err = 0; 467 set_close_on_exec(fd, argi & FD_CLOEXEC); 468 break; 469 case F_GETFL: 470 err = filp->f_flags; 471 break; 472 case F_SETFL: 473 err = setfl(fd, filp, argi); 474 break; 475 #if BITS_PER_LONG != 32 476 /* 32-bit arches must use fcntl64() */ 477 case F_OFD_GETLK: 478 #endif 479 case F_GETLK: 480 if (copy_from_user(&flock, argp, sizeof(flock))) 481 return -EFAULT; 482 err = fcntl_getlk(filp, cmd, &flock); 483 if (!err && copy_to_user(argp, &flock, sizeof(flock))) 484 return -EFAULT; 485 break; 486 #if BITS_PER_LONG != 32 487 /* 32-bit arches must use fcntl64() */ 488 case F_OFD_SETLK: 489 case F_OFD_SETLKW: 490 fallthrough; 491 #endif 492 case F_SETLK: 493 case F_SETLKW: 494 if (copy_from_user(&flock, argp, sizeof(flock))) 495 return -EFAULT; 496 err = fcntl_setlk(fd, filp, cmd, &flock); 497 break; 498 case F_GETOWN: 499 /* 500 * XXX If f_owner is a process group, the 501 * negative return value will get converted 502 * into an error. Oops. If we keep the 503 * current syscall conventions, the only way 504 * to fix this will be in libc. 505 */ 506 err = f_getown(filp); 507 force_successful_syscall_return(); 508 break; 509 case F_SETOWN: 510 err = f_setown(filp, argi, 1); 511 break; 512 case F_GETOWN_EX: 513 err = f_getown_ex(filp, arg); 514 break; 515 case F_SETOWN_EX: 516 err = f_setown_ex(filp, arg); 517 break; 518 case F_GETOWNER_UIDS: 519 err = f_getowner_uids(filp, arg); 520 break; 521 case F_GETSIG: 522 err = f_owner_sig(filp, 0, false); 523 break; 524 case F_SETSIG: 525 err = f_owner_sig(filp, argi, true); 526 break; 527 case F_GETLEASE: 528 err = fcntl_getlease(filp); 529 break; 530 case F_SETLEASE: 531 err = fcntl_setlease(fd, filp, argi); 532 break; 533 case F_NOTIFY: 534 err = fcntl_dirnotify(fd, filp, argi); 535 break; 536 case F_SETPIPE_SZ: 537 case F_GETPIPE_SZ: 538 err = pipe_fcntl(filp, cmd, argi); 539 break; 540 case F_ADD_SEALS: 541 case F_GET_SEALS: 542 err = memfd_fcntl(filp, cmd, argi); 543 break; 544 case F_GET_RW_HINT: 545 err = fcntl_get_rw_hint(filp, cmd, arg); 546 break; 547 case F_SET_RW_HINT: 548 err = fcntl_set_rw_hint(filp, cmd, arg); 549 break; 550 default: 551 break; 552 } 553 return err; 554 } 555 556 static int check_fcntl_cmd(unsigned cmd) 557 { 558 switch (cmd) { 559 case F_CREATED_QUERY: 560 case F_DUPFD: 561 case F_DUPFD_CLOEXEC: 562 case F_DUPFD_QUERY: 563 case F_GETFD: 564 case F_SETFD: 565 case F_GETFL: 566 return 1; 567 } 568 return 0; 569 } 570 571 SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg) 572 { 573 CLASS(fd_raw, f)(fd); 574 long err; 575 576 if (fd_empty(f)) 577 return -EBADF; 578 579 if (unlikely(fd_file(f)->f_mode & FMODE_PATH)) { 580 if (!check_fcntl_cmd(cmd)) 581 return -EBADF; 582 } 583 584 err = security_file_fcntl(fd_file(f), cmd, arg); 585 if (!err) 586 err = do_fcntl(fd, cmd, arg, fd_file(f)); 587 588 return err; 589 } 590 591 #if BITS_PER_LONG == 32 592 SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd, 593 unsigned long, arg) 594 { 595 void __user *argp = (void __user *)arg; 596 CLASS(fd_raw, f)(fd); 597 struct flock64 flock; 598 long err; 599 600 if (fd_empty(f)) 601 return -EBADF; 602 603 if (unlikely(fd_file(f)->f_mode & FMODE_PATH)) { 604 if (!check_fcntl_cmd(cmd)) 605 return -EBADF; 606 } 607 608 err = security_file_fcntl(fd_file(f), cmd, arg); 609 if (err) 610 return err; 611 612 switch (cmd) { 613 case F_GETLK64: 614 case F_OFD_GETLK: 615 err = -EFAULT; 616 if (copy_from_user(&flock, argp, sizeof(flock))) 617 break; 618 err = fcntl_getlk64(fd_file(f), cmd, &flock); 619 if (!err && copy_to_user(argp, &flock, sizeof(flock))) 620 err = -EFAULT; 621 break; 622 case F_SETLK64: 623 case F_SETLKW64: 624 case F_OFD_SETLK: 625 case F_OFD_SETLKW: 626 err = -EFAULT; 627 if (copy_from_user(&flock, argp, sizeof(flock))) 628 break; 629 err = fcntl_setlk64(fd, fd_file(f), cmd, &flock); 630 break; 631 default: 632 err = do_fcntl(fd, cmd, arg, fd_file(f)); 633 break; 634 } 635 return err; 636 } 637 #endif 638 639 #ifdef CONFIG_COMPAT 640 /* careful - don't use anywhere else */ 641 #define copy_flock_fields(dst, src) \ 642 (dst)->l_type = (src)->l_type; \ 643 (dst)->l_whence = (src)->l_whence; \ 644 (dst)->l_start = (src)->l_start; \ 645 (dst)->l_len = (src)->l_len; \ 646 (dst)->l_pid = (src)->l_pid; 647 648 static int get_compat_flock(struct flock *kfl, const struct compat_flock __user *ufl) 649 { 650 struct compat_flock fl; 651 652 if (copy_from_user(&fl, ufl, sizeof(struct compat_flock))) 653 return -EFAULT; 654 copy_flock_fields(kfl, &fl); 655 return 0; 656 } 657 658 static int get_compat_flock64(struct flock *kfl, const struct compat_flock64 __user *ufl) 659 { 660 struct compat_flock64 fl; 661 662 if (copy_from_user(&fl, ufl, sizeof(struct compat_flock64))) 663 return -EFAULT; 664 copy_flock_fields(kfl, &fl); 665 return 0; 666 } 667 668 static int put_compat_flock(const struct flock *kfl, struct compat_flock __user *ufl) 669 { 670 struct compat_flock fl; 671 672 memset(&fl, 0, sizeof(struct compat_flock)); 673 copy_flock_fields(&fl, kfl); 674 if (copy_to_user(ufl, &fl, sizeof(struct compat_flock))) 675 return -EFAULT; 676 return 0; 677 } 678 679 static int put_compat_flock64(const struct flock *kfl, struct compat_flock64 __user *ufl) 680 { 681 struct compat_flock64 fl; 682 683 BUILD_BUG_ON(sizeof(kfl->l_start) > sizeof(ufl->l_start)); 684 BUILD_BUG_ON(sizeof(kfl->l_len) > sizeof(ufl->l_len)); 685 686 memset(&fl, 0, sizeof(struct compat_flock64)); 687 copy_flock_fields(&fl, kfl); 688 if (copy_to_user(ufl, &fl, sizeof(struct compat_flock64))) 689 return -EFAULT; 690 return 0; 691 } 692 #undef copy_flock_fields 693 694 static unsigned int 695 convert_fcntl_cmd(unsigned int cmd) 696 { 697 switch (cmd) { 698 case F_GETLK64: 699 return F_GETLK; 700 case F_SETLK64: 701 return F_SETLK; 702 case F_SETLKW64: 703 return F_SETLKW; 704 } 705 706 return cmd; 707 } 708 709 /* 710 * GETLK was successful and we need to return the data, but it needs to fit in 711 * the compat structure. 712 * l_start shouldn't be too big, unless the original start + end is greater than 713 * COMPAT_OFF_T_MAX, in which case the app was asking for trouble, so we return 714 * -EOVERFLOW in that case. l_len could be too big, in which case we just 715 * truncate it, and only allow the app to see that part of the conflicting lock 716 * that might make sense to it anyway 717 */ 718 static int fixup_compat_flock(struct flock *flock) 719 { 720 if (flock->l_start > COMPAT_OFF_T_MAX) 721 return -EOVERFLOW; 722 if (flock->l_len > COMPAT_OFF_T_MAX) 723 flock->l_len = COMPAT_OFF_T_MAX; 724 return 0; 725 } 726 727 static long do_compat_fcntl64(unsigned int fd, unsigned int cmd, 728 compat_ulong_t arg) 729 { 730 CLASS(fd_raw, f)(fd); 731 struct flock flock; 732 long err; 733 734 if (fd_empty(f)) 735 return -EBADF; 736 737 if (unlikely(fd_file(f)->f_mode & FMODE_PATH)) { 738 if (!check_fcntl_cmd(cmd)) 739 return -EBADF; 740 } 741 742 err = security_file_fcntl(fd_file(f), cmd, arg); 743 if (err) 744 return err; 745 746 switch (cmd) { 747 case F_GETLK: 748 err = get_compat_flock(&flock, compat_ptr(arg)); 749 if (err) 750 break; 751 err = fcntl_getlk(fd_file(f), convert_fcntl_cmd(cmd), &flock); 752 if (err) 753 break; 754 err = fixup_compat_flock(&flock); 755 if (!err) 756 err = put_compat_flock(&flock, compat_ptr(arg)); 757 break; 758 case F_GETLK64: 759 case F_OFD_GETLK: 760 err = get_compat_flock64(&flock, compat_ptr(arg)); 761 if (err) 762 break; 763 err = fcntl_getlk(fd_file(f), convert_fcntl_cmd(cmd), &flock); 764 if (!err) 765 err = put_compat_flock64(&flock, compat_ptr(arg)); 766 break; 767 case F_SETLK: 768 case F_SETLKW: 769 err = get_compat_flock(&flock, compat_ptr(arg)); 770 if (err) 771 break; 772 err = fcntl_setlk(fd, fd_file(f), convert_fcntl_cmd(cmd), &flock); 773 break; 774 case F_SETLK64: 775 case F_SETLKW64: 776 case F_OFD_SETLK: 777 case F_OFD_SETLKW: 778 err = get_compat_flock64(&flock, compat_ptr(arg)); 779 if (err) 780 break; 781 err = fcntl_setlk(fd, fd_file(f), convert_fcntl_cmd(cmd), &flock); 782 break; 783 default: 784 err = do_fcntl(fd, cmd, arg, fd_file(f)); 785 break; 786 } 787 return err; 788 } 789 790 COMPAT_SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd, 791 compat_ulong_t, arg) 792 { 793 return do_compat_fcntl64(fd, cmd, arg); 794 } 795 796 COMPAT_SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, 797 compat_ulong_t, arg) 798 { 799 switch (cmd) { 800 case F_GETLK64: 801 case F_SETLK64: 802 case F_SETLKW64: 803 case F_OFD_GETLK: 804 case F_OFD_SETLK: 805 case F_OFD_SETLKW: 806 return -EINVAL; 807 } 808 return do_compat_fcntl64(fd, cmd, arg); 809 } 810 #endif 811 812 /* Table to convert sigio signal codes into poll band bitmaps */ 813 814 static const __poll_t band_table[NSIGPOLL] = { 815 EPOLLIN | EPOLLRDNORM, /* POLL_IN */ 816 EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND, /* POLL_OUT */ 817 EPOLLIN | EPOLLRDNORM | EPOLLMSG, /* POLL_MSG */ 818 EPOLLERR, /* POLL_ERR */ 819 EPOLLPRI | EPOLLRDBAND, /* POLL_PRI */ 820 EPOLLHUP | EPOLLERR /* POLL_HUP */ 821 }; 822 823 static inline int sigio_perm(struct task_struct *p, 824 struct fown_struct *fown, int sig) 825 { 826 const struct cred *cred; 827 int ret; 828 829 rcu_read_lock(); 830 cred = __task_cred(p); 831 ret = ((uid_eq(fown->euid, GLOBAL_ROOT_UID) || 832 uid_eq(fown->euid, cred->suid) || uid_eq(fown->euid, cred->uid) || 833 uid_eq(fown->uid, cred->suid) || uid_eq(fown->uid, cred->uid)) && 834 !security_file_send_sigiotask(p, fown, sig)); 835 rcu_read_unlock(); 836 return ret; 837 } 838 839 static void send_sigio_to_task(struct task_struct *p, 840 struct fown_struct *fown, 841 int fd, int reason, enum pid_type type) 842 { 843 /* 844 * F_SETSIG can change ->signum lockless in parallel, make 845 * sure we read it once and use the same value throughout. 846 */ 847 int signum = READ_ONCE(fown->signum); 848 849 if (!sigio_perm(p, fown, signum)) 850 return; 851 852 switch (signum) { 853 default: { 854 kernel_siginfo_t si; 855 856 /* Queue a rt signal with the appropriate fd as its 857 value. We use SI_SIGIO as the source, not 858 SI_KERNEL, since kernel signals always get 859 delivered even if we can't queue. Failure to 860 queue in this case _should_ be reported; we fall 861 back to SIGIO in that case. --sct */ 862 clear_siginfo(&si); 863 si.si_signo = signum; 864 si.si_errno = 0; 865 si.si_code = reason; 866 /* 867 * Posix definies POLL_IN and friends to be signal 868 * specific si_codes for SIG_POLL. Linux extended 869 * these si_codes to other signals in a way that is 870 * ambiguous if other signals also have signal 871 * specific si_codes. In that case use SI_SIGIO instead 872 * to remove the ambiguity. 873 */ 874 if ((signum != SIGPOLL) && sig_specific_sicodes(signum)) 875 si.si_code = SI_SIGIO; 876 877 /* Make sure we are called with one of the POLL_* 878 reasons, otherwise we could leak kernel stack into 879 userspace. */ 880 BUG_ON((reason < POLL_IN) || ((reason - POLL_IN) >= NSIGPOLL)); 881 if (reason - POLL_IN >= NSIGPOLL) 882 si.si_band = ~0L; 883 else 884 si.si_band = mangle_poll(band_table[reason - POLL_IN]); 885 si.si_fd = fd; 886 if (!do_send_sig_info(signum, &si, p, type)) 887 break; 888 } 889 fallthrough; /* fall back on the old plain SIGIO signal */ 890 case 0: 891 do_send_sig_info(SIGIO, SEND_SIG_PRIV, p, type); 892 } 893 } 894 895 void send_sigio(struct fown_struct *fown, int fd, int band) 896 { 897 struct task_struct *p; 898 enum pid_type type; 899 unsigned long flags; 900 struct pid *pid; 901 902 read_lock_irqsave(&fown->lock, flags); 903 904 type = fown->pid_type; 905 pid = fown->pid; 906 if (!pid) 907 goto out_unlock_fown; 908 909 if (type <= PIDTYPE_TGID) { 910 rcu_read_lock(); 911 p = pid_task(pid, PIDTYPE_PID); 912 if (p) 913 send_sigio_to_task(p, fown, fd, band, type); 914 rcu_read_unlock(); 915 } else { 916 read_lock(&tasklist_lock); 917 do_each_pid_task(pid, type, p) { 918 send_sigio_to_task(p, fown, fd, band, type); 919 } while_each_pid_task(pid, type, p); 920 read_unlock(&tasklist_lock); 921 } 922 out_unlock_fown: 923 read_unlock_irqrestore(&fown->lock, flags); 924 } 925 926 static void send_sigurg_to_task(struct task_struct *p, 927 struct fown_struct *fown, enum pid_type type) 928 { 929 if (sigio_perm(p, fown, SIGURG)) 930 do_send_sig_info(SIGURG, SEND_SIG_PRIV, p, type); 931 } 932 933 int send_sigurg(struct file *file) 934 { 935 struct fown_struct *fown; 936 struct task_struct *p; 937 enum pid_type type; 938 struct pid *pid; 939 unsigned long flags; 940 int ret = 0; 941 942 fown = file_f_owner(file); 943 if (!fown) 944 return 0; 945 946 read_lock_irqsave(&fown->lock, flags); 947 948 type = fown->pid_type; 949 pid = fown->pid; 950 if (!pid) 951 goto out_unlock_fown; 952 953 ret = 1; 954 955 if (type <= PIDTYPE_TGID) { 956 rcu_read_lock(); 957 p = pid_task(pid, PIDTYPE_PID); 958 if (p) 959 send_sigurg_to_task(p, fown, type); 960 rcu_read_unlock(); 961 } else { 962 read_lock(&tasklist_lock); 963 do_each_pid_task(pid, type, p) { 964 send_sigurg_to_task(p, fown, type); 965 } while_each_pid_task(pid, type, p); 966 read_unlock(&tasklist_lock); 967 } 968 out_unlock_fown: 969 read_unlock_irqrestore(&fown->lock, flags); 970 return ret; 971 } 972 973 static DEFINE_SPINLOCK(fasync_lock); 974 static struct kmem_cache *fasync_cache __ro_after_init; 975 976 /* 977 * Remove a fasync entry. If successfully removed, return 978 * positive and clear the FASYNC flag. If no entry exists, 979 * do nothing and return 0. 980 * 981 * NOTE! It is very important that the FASYNC flag always 982 * match the state "is the filp on a fasync list". 983 * 984 */ 985 int fasync_remove_entry(struct file *filp, struct fasync_struct **fapp) 986 { 987 struct fasync_struct *fa, **fp; 988 int result = 0; 989 990 spin_lock(&filp->f_lock); 991 spin_lock(&fasync_lock); 992 for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) { 993 if (fa->fa_file != filp) 994 continue; 995 996 write_lock_irq(&fa->fa_lock); 997 fa->fa_file = NULL; 998 write_unlock_irq(&fa->fa_lock); 999 1000 *fp = fa->fa_next; 1001 kfree_rcu(fa, fa_rcu); 1002 filp->f_flags &= ~FASYNC; 1003 result = 1; 1004 break; 1005 } 1006 spin_unlock(&fasync_lock); 1007 spin_unlock(&filp->f_lock); 1008 return result; 1009 } 1010 1011 struct fasync_struct *fasync_alloc(void) 1012 { 1013 return kmem_cache_alloc(fasync_cache, GFP_KERNEL); 1014 } 1015 1016 /* 1017 * NOTE! This can be used only for unused fasync entries: 1018 * entries that actually got inserted on the fasync list 1019 * need to be released by rcu - see fasync_remove_entry. 1020 */ 1021 void fasync_free(struct fasync_struct *new) 1022 { 1023 kmem_cache_free(fasync_cache, new); 1024 } 1025 1026 /* 1027 * Insert a new entry into the fasync list. Return the pointer to the 1028 * old one if we didn't use the new one. 1029 * 1030 * NOTE! It is very important that the FASYNC flag always 1031 * match the state "is the filp on a fasync list". 1032 */ 1033 struct fasync_struct *fasync_insert_entry(int fd, struct file *filp, struct fasync_struct **fapp, struct fasync_struct *new) 1034 { 1035 struct fasync_struct *fa, **fp; 1036 1037 spin_lock(&filp->f_lock); 1038 spin_lock(&fasync_lock); 1039 for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) { 1040 if (fa->fa_file != filp) 1041 continue; 1042 1043 write_lock_irq(&fa->fa_lock); 1044 fa->fa_fd = fd; 1045 write_unlock_irq(&fa->fa_lock); 1046 goto out; 1047 } 1048 1049 rwlock_init(&new->fa_lock); 1050 new->magic = FASYNC_MAGIC; 1051 new->fa_file = filp; 1052 new->fa_fd = fd; 1053 new->fa_next = *fapp; 1054 rcu_assign_pointer(*fapp, new); 1055 filp->f_flags |= FASYNC; 1056 1057 out: 1058 spin_unlock(&fasync_lock); 1059 spin_unlock(&filp->f_lock); 1060 return fa; 1061 } 1062 1063 /* 1064 * Add a fasync entry. Return negative on error, positive if 1065 * added, and zero if did nothing but change an existing one. 1066 */ 1067 static int fasync_add_entry(int fd, struct file *filp, struct fasync_struct **fapp) 1068 { 1069 struct fasync_struct *new; 1070 1071 new = fasync_alloc(); 1072 if (!new) 1073 return -ENOMEM; 1074 1075 /* 1076 * fasync_insert_entry() returns the old (update) entry if 1077 * it existed. 1078 * 1079 * So free the (unused) new entry and return 0 to let the 1080 * caller know that we didn't add any new fasync entries. 1081 */ 1082 if (fasync_insert_entry(fd, filp, fapp, new)) { 1083 fasync_free(new); 1084 return 0; 1085 } 1086 1087 return 1; 1088 } 1089 1090 /* 1091 * fasync_helper() is used by almost all character device drivers 1092 * to set up the fasync queue, and for regular files by the file 1093 * lease code. It returns negative on error, 0 if it did no changes 1094 * and positive if it added/deleted the entry. 1095 */ 1096 int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp) 1097 { 1098 if (!on) 1099 return fasync_remove_entry(filp, fapp); 1100 return fasync_add_entry(fd, filp, fapp); 1101 } 1102 1103 EXPORT_SYMBOL(fasync_helper); 1104 1105 /* 1106 * rcu_read_lock() is held 1107 */ 1108 static void kill_fasync_rcu(struct fasync_struct *fa, int sig, int band) 1109 { 1110 while (fa) { 1111 struct fown_struct *fown; 1112 unsigned long flags; 1113 1114 if (fa->magic != FASYNC_MAGIC) { 1115 printk(KERN_ERR "kill_fasync: bad magic number in " 1116 "fasync_struct!\n"); 1117 return; 1118 } 1119 read_lock_irqsave(&fa->fa_lock, flags); 1120 if (fa->fa_file) { 1121 fown = file_f_owner(fa->fa_file); 1122 if (!fown) 1123 goto next; 1124 /* Don't send SIGURG to processes which have not set a 1125 queued signum: SIGURG has its own default signalling 1126 mechanism. */ 1127 if (!(sig == SIGURG && fown->signum == 0)) 1128 send_sigio(fown, fa->fa_fd, band); 1129 } 1130 next: 1131 read_unlock_irqrestore(&fa->fa_lock, flags); 1132 fa = rcu_dereference(fa->fa_next); 1133 } 1134 } 1135 1136 void kill_fasync(struct fasync_struct **fp, int sig, int band) 1137 { 1138 /* First a quick test without locking: usually 1139 * the list is empty. 1140 */ 1141 if (*fp) { 1142 rcu_read_lock(); 1143 kill_fasync_rcu(rcu_dereference(*fp), sig, band); 1144 rcu_read_unlock(); 1145 } 1146 } 1147 EXPORT_SYMBOL(kill_fasync); 1148 1149 static int __init fcntl_init(void) 1150 { 1151 /* 1152 * Please add new bits here to ensure allocation uniqueness. 1153 * Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY 1154 * is defined as O_NONBLOCK on some platforms and not on others. 1155 */ 1156 BUILD_BUG_ON(21 - 1 /* for O_RDONLY being 0 */ != 1157 HWEIGHT32( 1158 (VALID_OPEN_FLAGS & ~(O_NONBLOCK | O_NDELAY)) | 1159 __FMODE_EXEC | __FMODE_NONOTIFY)); 1160 1161 fasync_cache = kmem_cache_create("fasync_cache", 1162 sizeof(struct fasync_struct), 0, 1163 SLAB_PANIC | SLAB_ACCOUNT, NULL); 1164 return 0; 1165 } 1166 1167 module_init(fcntl_init) 1168