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 #define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT | O_NOATIME) 37 38 static int setfl(int fd, struct file * filp, unsigned int arg) 39 { 40 struct inode * inode = file_inode(filp); 41 int error = 0; 42 43 /* 44 * O_APPEND cannot be cleared if the file is marked as append-only 45 * and the file is open for write. 46 */ 47 if (((arg ^ filp->f_flags) & O_APPEND) && IS_APPEND(inode)) 48 return -EPERM; 49 50 /* O_NOATIME can only be set by the owner or superuser */ 51 if ((arg & O_NOATIME) && !(filp->f_flags & O_NOATIME)) 52 if (!inode_owner_or_capable(file_mnt_idmap(filp), inode)) 53 return -EPERM; 54 55 /* required for strict SunOS emulation */ 56 if (O_NONBLOCK != O_NDELAY) 57 if (arg & O_NDELAY) 58 arg |= O_NONBLOCK; 59 60 /* Pipe packetized mode is controlled by O_DIRECT flag */ 61 if (!S_ISFIFO(inode->i_mode) && 62 (arg & O_DIRECT) && 63 !(filp->f_mode & FMODE_CAN_ODIRECT)) 64 return -EINVAL; 65 66 if (filp->f_op->check_flags) 67 error = filp->f_op->check_flags(arg); 68 if (error) 69 return error; 70 71 /* 72 * ->fasync() is responsible for setting the FASYNC bit. 73 */ 74 if (((arg ^ filp->f_flags) & FASYNC) && filp->f_op->fasync) { 75 error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0); 76 if (error < 0) 77 goto out; 78 if (error > 0) 79 error = 0; 80 } 81 spin_lock(&filp->f_lock); 82 filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK); 83 filp->f_iocb_flags = iocb_flags(filp); 84 spin_unlock(&filp->f_lock); 85 86 out: 87 return error; 88 } 89 90 static void f_modown(struct file *filp, struct pid *pid, enum pid_type type, 91 int force) 92 { 93 write_lock_irq(&filp->f_owner.lock); 94 if (force || !filp->f_owner.pid) { 95 put_pid(filp->f_owner.pid); 96 filp->f_owner.pid = get_pid(pid); 97 filp->f_owner.pid_type = type; 98 99 if (pid) { 100 const struct cred *cred = current_cred(); 101 filp->f_owner.uid = cred->uid; 102 filp->f_owner.euid = cred->euid; 103 } 104 } 105 write_unlock_irq(&filp->f_owner.lock); 106 } 107 108 void __f_setown(struct file *filp, struct pid *pid, enum pid_type type, 109 int force) 110 { 111 security_file_set_fowner(filp); 112 f_modown(filp, pid, type, force); 113 } 114 EXPORT_SYMBOL(__f_setown); 115 116 int f_setown(struct file *filp, int who, int force) 117 { 118 enum pid_type type; 119 struct pid *pid = NULL; 120 int ret = 0; 121 122 type = PIDTYPE_TGID; 123 if (who < 0) { 124 /* avoid overflow below */ 125 if (who == INT_MIN) 126 return -EINVAL; 127 128 type = PIDTYPE_PGID; 129 who = -who; 130 } 131 132 rcu_read_lock(); 133 if (who) { 134 pid = find_vpid(who); 135 if (!pid) 136 ret = -ESRCH; 137 } 138 139 if (!ret) 140 __f_setown(filp, pid, type, force); 141 rcu_read_unlock(); 142 143 return ret; 144 } 145 EXPORT_SYMBOL(f_setown); 146 147 void f_delown(struct file *filp) 148 { 149 f_modown(filp, NULL, PIDTYPE_TGID, 1); 150 } 151 152 pid_t f_getown(struct file *filp) 153 { 154 pid_t pid = 0; 155 156 read_lock_irq(&filp->f_owner.lock); 157 rcu_read_lock(); 158 if (pid_task(filp->f_owner.pid, filp->f_owner.pid_type)) { 159 pid = pid_vnr(filp->f_owner.pid); 160 if (filp->f_owner.pid_type == PIDTYPE_PGID) 161 pid = -pid; 162 } 163 rcu_read_unlock(); 164 read_unlock_irq(&filp->f_owner.lock); 165 return pid; 166 } 167 168 static int f_setown_ex(struct file *filp, unsigned long arg) 169 { 170 struct f_owner_ex __user *owner_p = (void __user *)arg; 171 struct f_owner_ex owner; 172 struct pid *pid; 173 int type; 174 int ret; 175 176 ret = copy_from_user(&owner, owner_p, sizeof(owner)); 177 if (ret) 178 return -EFAULT; 179 180 switch (owner.type) { 181 case F_OWNER_TID: 182 type = PIDTYPE_PID; 183 break; 184 185 case F_OWNER_PID: 186 type = PIDTYPE_TGID; 187 break; 188 189 case F_OWNER_PGRP: 190 type = PIDTYPE_PGID; 191 break; 192 193 default: 194 return -EINVAL; 195 } 196 197 rcu_read_lock(); 198 pid = find_vpid(owner.pid); 199 if (owner.pid && !pid) 200 ret = -ESRCH; 201 else 202 __f_setown(filp, pid, type, 1); 203 rcu_read_unlock(); 204 205 return ret; 206 } 207 208 static int f_getown_ex(struct file *filp, unsigned long arg) 209 { 210 struct f_owner_ex __user *owner_p = (void __user *)arg; 211 struct f_owner_ex owner = {}; 212 int ret = 0; 213 214 read_lock_irq(&filp->f_owner.lock); 215 rcu_read_lock(); 216 if (pid_task(filp->f_owner.pid, filp->f_owner.pid_type)) 217 owner.pid = pid_vnr(filp->f_owner.pid); 218 rcu_read_unlock(); 219 switch (filp->f_owner.pid_type) { 220 case PIDTYPE_PID: 221 owner.type = F_OWNER_TID; 222 break; 223 224 case PIDTYPE_TGID: 225 owner.type = F_OWNER_PID; 226 break; 227 228 case PIDTYPE_PGID: 229 owner.type = F_OWNER_PGRP; 230 break; 231 232 default: 233 WARN_ON(1); 234 ret = -EINVAL; 235 break; 236 } 237 read_unlock_irq(&filp->f_owner.lock); 238 239 if (!ret) { 240 ret = copy_to_user(owner_p, &owner, sizeof(owner)); 241 if (ret) 242 ret = -EFAULT; 243 } 244 return ret; 245 } 246 247 #ifdef CONFIG_CHECKPOINT_RESTORE 248 static int f_getowner_uids(struct file *filp, unsigned long arg) 249 { 250 struct user_namespace *user_ns = current_user_ns(); 251 uid_t __user *dst = (void __user *)arg; 252 uid_t src[2]; 253 int err; 254 255 read_lock_irq(&filp->f_owner.lock); 256 src[0] = from_kuid(user_ns, filp->f_owner.uid); 257 src[1] = from_kuid(user_ns, filp->f_owner.euid); 258 read_unlock_irq(&filp->f_owner.lock); 259 260 err = put_user(src[0], &dst[0]); 261 err |= put_user(src[1], &dst[1]); 262 263 return err; 264 } 265 #else 266 static int f_getowner_uids(struct file *filp, unsigned long arg) 267 { 268 return -EINVAL; 269 } 270 #endif 271 272 static bool rw_hint_valid(u64 hint) 273 { 274 BUILD_BUG_ON(WRITE_LIFE_NOT_SET != RWH_WRITE_LIFE_NOT_SET); 275 BUILD_BUG_ON(WRITE_LIFE_NONE != RWH_WRITE_LIFE_NONE); 276 BUILD_BUG_ON(WRITE_LIFE_SHORT != RWH_WRITE_LIFE_SHORT); 277 BUILD_BUG_ON(WRITE_LIFE_MEDIUM != RWH_WRITE_LIFE_MEDIUM); 278 BUILD_BUG_ON(WRITE_LIFE_LONG != RWH_WRITE_LIFE_LONG); 279 BUILD_BUG_ON(WRITE_LIFE_EXTREME != RWH_WRITE_LIFE_EXTREME); 280 281 switch (hint) { 282 case RWH_WRITE_LIFE_NOT_SET: 283 case RWH_WRITE_LIFE_NONE: 284 case RWH_WRITE_LIFE_SHORT: 285 case RWH_WRITE_LIFE_MEDIUM: 286 case RWH_WRITE_LIFE_LONG: 287 case RWH_WRITE_LIFE_EXTREME: 288 return true; 289 default: 290 return false; 291 } 292 } 293 294 static long fcntl_get_rw_hint(struct file *file, unsigned int cmd, 295 unsigned long arg) 296 { 297 struct inode *inode = file_inode(file); 298 u64 __user *argp = (u64 __user *)arg; 299 u64 hint = READ_ONCE(inode->i_write_hint); 300 301 if (copy_to_user(argp, &hint, sizeof(*argp))) 302 return -EFAULT; 303 return 0; 304 } 305 306 static long fcntl_set_rw_hint(struct file *file, unsigned int cmd, 307 unsigned long arg) 308 { 309 struct inode *inode = file_inode(file); 310 u64 __user *argp = (u64 __user *)arg; 311 u64 hint; 312 313 if (copy_from_user(&hint, argp, sizeof(hint))) 314 return -EFAULT; 315 if (!rw_hint_valid(hint)) 316 return -EINVAL; 317 318 WRITE_ONCE(inode->i_write_hint, hint); 319 320 /* 321 * file->f_mapping->host may differ from inode. As an example, 322 * blkdev_open() modifies file->f_mapping. 323 */ 324 if (file->f_mapping->host != inode) 325 WRITE_ONCE(file->f_mapping->host->i_write_hint, hint); 326 327 return 0; 328 } 329 330 static long do_fcntl(int fd, unsigned int cmd, unsigned long arg, 331 struct file *filp) 332 { 333 void __user *argp = (void __user *)arg; 334 int argi = (int)arg; 335 struct flock flock; 336 long err = -EINVAL; 337 338 switch (cmd) { 339 case F_DUPFD: 340 err = f_dupfd(argi, filp, 0); 341 break; 342 case F_DUPFD_CLOEXEC: 343 err = f_dupfd(argi, filp, O_CLOEXEC); 344 break; 345 case F_GETFD: 346 err = get_close_on_exec(fd) ? FD_CLOEXEC : 0; 347 break; 348 case F_SETFD: 349 err = 0; 350 set_close_on_exec(fd, argi & FD_CLOEXEC); 351 break; 352 case F_GETFL: 353 err = filp->f_flags; 354 break; 355 case F_SETFL: 356 err = setfl(fd, filp, argi); 357 break; 358 #if BITS_PER_LONG != 32 359 /* 32-bit arches must use fcntl64() */ 360 case F_OFD_GETLK: 361 #endif 362 case F_GETLK: 363 if (copy_from_user(&flock, argp, sizeof(flock))) 364 return -EFAULT; 365 err = fcntl_getlk(filp, cmd, &flock); 366 if (!err && copy_to_user(argp, &flock, sizeof(flock))) 367 return -EFAULT; 368 break; 369 #if BITS_PER_LONG != 32 370 /* 32-bit arches must use fcntl64() */ 371 case F_OFD_SETLK: 372 case F_OFD_SETLKW: 373 fallthrough; 374 #endif 375 case F_SETLK: 376 case F_SETLKW: 377 if (copy_from_user(&flock, argp, sizeof(flock))) 378 return -EFAULT; 379 err = fcntl_setlk(fd, filp, cmd, &flock); 380 break; 381 case F_GETOWN: 382 /* 383 * XXX If f_owner is a process group, the 384 * negative return value will get converted 385 * into an error. Oops. If we keep the 386 * current syscall conventions, the only way 387 * to fix this will be in libc. 388 */ 389 err = f_getown(filp); 390 force_successful_syscall_return(); 391 break; 392 case F_SETOWN: 393 err = f_setown(filp, argi, 1); 394 break; 395 case F_GETOWN_EX: 396 err = f_getown_ex(filp, arg); 397 break; 398 case F_SETOWN_EX: 399 err = f_setown_ex(filp, arg); 400 break; 401 case F_GETOWNER_UIDS: 402 err = f_getowner_uids(filp, arg); 403 break; 404 case F_GETSIG: 405 err = filp->f_owner.signum; 406 break; 407 case F_SETSIG: 408 /* arg == 0 restores default behaviour. */ 409 if (!valid_signal(argi)) { 410 break; 411 } 412 err = 0; 413 filp->f_owner.signum = argi; 414 break; 415 case F_GETLEASE: 416 err = fcntl_getlease(filp); 417 break; 418 case F_SETLEASE: 419 err = fcntl_setlease(fd, filp, argi); 420 break; 421 case F_NOTIFY: 422 err = fcntl_dirnotify(fd, filp, argi); 423 break; 424 case F_SETPIPE_SZ: 425 case F_GETPIPE_SZ: 426 err = pipe_fcntl(filp, cmd, argi); 427 break; 428 case F_ADD_SEALS: 429 case F_GET_SEALS: 430 err = memfd_fcntl(filp, cmd, argi); 431 break; 432 case F_GET_RW_HINT: 433 err = fcntl_get_rw_hint(filp, cmd, arg); 434 break; 435 case F_SET_RW_HINT: 436 err = fcntl_set_rw_hint(filp, cmd, arg); 437 break; 438 default: 439 break; 440 } 441 return err; 442 } 443 444 static int check_fcntl_cmd(unsigned cmd) 445 { 446 switch (cmd) { 447 case F_DUPFD: 448 case F_DUPFD_CLOEXEC: 449 case F_GETFD: 450 case F_SETFD: 451 case F_GETFL: 452 return 1; 453 } 454 return 0; 455 } 456 457 SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg) 458 { 459 struct fd f = fdget_raw(fd); 460 long err = -EBADF; 461 462 if (!f.file) 463 goto out; 464 465 if (unlikely(f.file->f_mode & FMODE_PATH)) { 466 if (!check_fcntl_cmd(cmd)) 467 goto out1; 468 } 469 470 err = security_file_fcntl(f.file, cmd, arg); 471 if (!err) 472 err = do_fcntl(fd, cmd, arg, f.file); 473 474 out1: 475 fdput(f); 476 out: 477 return err; 478 } 479 480 #if BITS_PER_LONG == 32 481 SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd, 482 unsigned long, arg) 483 { 484 void __user *argp = (void __user *)arg; 485 struct fd f = fdget_raw(fd); 486 struct flock64 flock; 487 long err = -EBADF; 488 489 if (!f.file) 490 goto out; 491 492 if (unlikely(f.file->f_mode & FMODE_PATH)) { 493 if (!check_fcntl_cmd(cmd)) 494 goto out1; 495 } 496 497 err = security_file_fcntl(f.file, cmd, arg); 498 if (err) 499 goto out1; 500 501 switch (cmd) { 502 case F_GETLK64: 503 case F_OFD_GETLK: 504 err = -EFAULT; 505 if (copy_from_user(&flock, argp, sizeof(flock))) 506 break; 507 err = fcntl_getlk64(f.file, cmd, &flock); 508 if (!err && copy_to_user(argp, &flock, sizeof(flock))) 509 err = -EFAULT; 510 break; 511 case F_SETLK64: 512 case F_SETLKW64: 513 case F_OFD_SETLK: 514 case F_OFD_SETLKW: 515 err = -EFAULT; 516 if (copy_from_user(&flock, argp, sizeof(flock))) 517 break; 518 err = fcntl_setlk64(fd, f.file, cmd, &flock); 519 break; 520 default: 521 err = do_fcntl(fd, cmd, arg, f.file); 522 break; 523 } 524 out1: 525 fdput(f); 526 out: 527 return err; 528 } 529 #endif 530 531 #ifdef CONFIG_COMPAT 532 /* careful - don't use anywhere else */ 533 #define copy_flock_fields(dst, src) \ 534 (dst)->l_type = (src)->l_type; \ 535 (dst)->l_whence = (src)->l_whence; \ 536 (dst)->l_start = (src)->l_start; \ 537 (dst)->l_len = (src)->l_len; \ 538 (dst)->l_pid = (src)->l_pid; 539 540 static int get_compat_flock(struct flock *kfl, const struct compat_flock __user *ufl) 541 { 542 struct compat_flock fl; 543 544 if (copy_from_user(&fl, ufl, sizeof(struct compat_flock))) 545 return -EFAULT; 546 copy_flock_fields(kfl, &fl); 547 return 0; 548 } 549 550 static int get_compat_flock64(struct flock *kfl, const struct compat_flock64 __user *ufl) 551 { 552 struct compat_flock64 fl; 553 554 if (copy_from_user(&fl, ufl, sizeof(struct compat_flock64))) 555 return -EFAULT; 556 copy_flock_fields(kfl, &fl); 557 return 0; 558 } 559 560 static int put_compat_flock(const struct flock *kfl, struct compat_flock __user *ufl) 561 { 562 struct compat_flock fl; 563 564 memset(&fl, 0, sizeof(struct compat_flock)); 565 copy_flock_fields(&fl, kfl); 566 if (copy_to_user(ufl, &fl, sizeof(struct compat_flock))) 567 return -EFAULT; 568 return 0; 569 } 570 571 static int put_compat_flock64(const struct flock *kfl, struct compat_flock64 __user *ufl) 572 { 573 struct compat_flock64 fl; 574 575 BUILD_BUG_ON(sizeof(kfl->l_start) > sizeof(ufl->l_start)); 576 BUILD_BUG_ON(sizeof(kfl->l_len) > sizeof(ufl->l_len)); 577 578 memset(&fl, 0, sizeof(struct compat_flock64)); 579 copy_flock_fields(&fl, kfl); 580 if (copy_to_user(ufl, &fl, sizeof(struct compat_flock64))) 581 return -EFAULT; 582 return 0; 583 } 584 #undef copy_flock_fields 585 586 static unsigned int 587 convert_fcntl_cmd(unsigned int cmd) 588 { 589 switch (cmd) { 590 case F_GETLK64: 591 return F_GETLK; 592 case F_SETLK64: 593 return F_SETLK; 594 case F_SETLKW64: 595 return F_SETLKW; 596 } 597 598 return cmd; 599 } 600 601 /* 602 * GETLK was successful and we need to return the data, but it needs to fit in 603 * the compat structure. 604 * l_start shouldn't be too big, unless the original start + end is greater than 605 * COMPAT_OFF_T_MAX, in which case the app was asking for trouble, so we return 606 * -EOVERFLOW in that case. l_len could be too big, in which case we just 607 * truncate it, and only allow the app to see that part of the conflicting lock 608 * that might make sense to it anyway 609 */ 610 static int fixup_compat_flock(struct flock *flock) 611 { 612 if (flock->l_start > COMPAT_OFF_T_MAX) 613 return -EOVERFLOW; 614 if (flock->l_len > COMPAT_OFF_T_MAX) 615 flock->l_len = COMPAT_OFF_T_MAX; 616 return 0; 617 } 618 619 static long do_compat_fcntl64(unsigned int fd, unsigned int cmd, 620 compat_ulong_t arg) 621 { 622 struct fd f = fdget_raw(fd); 623 struct flock flock; 624 long err = -EBADF; 625 626 if (!f.file) 627 return err; 628 629 if (unlikely(f.file->f_mode & FMODE_PATH)) { 630 if (!check_fcntl_cmd(cmd)) 631 goto out_put; 632 } 633 634 err = security_file_fcntl(f.file, cmd, arg); 635 if (err) 636 goto out_put; 637 638 switch (cmd) { 639 case F_GETLK: 640 err = get_compat_flock(&flock, compat_ptr(arg)); 641 if (err) 642 break; 643 err = fcntl_getlk(f.file, convert_fcntl_cmd(cmd), &flock); 644 if (err) 645 break; 646 err = fixup_compat_flock(&flock); 647 if (!err) 648 err = put_compat_flock(&flock, compat_ptr(arg)); 649 break; 650 case F_GETLK64: 651 case F_OFD_GETLK: 652 err = get_compat_flock64(&flock, compat_ptr(arg)); 653 if (err) 654 break; 655 err = fcntl_getlk(f.file, convert_fcntl_cmd(cmd), &flock); 656 if (!err) 657 err = put_compat_flock64(&flock, compat_ptr(arg)); 658 break; 659 case F_SETLK: 660 case F_SETLKW: 661 err = get_compat_flock(&flock, compat_ptr(arg)); 662 if (err) 663 break; 664 err = fcntl_setlk(fd, f.file, convert_fcntl_cmd(cmd), &flock); 665 break; 666 case F_SETLK64: 667 case F_SETLKW64: 668 case F_OFD_SETLK: 669 case F_OFD_SETLKW: 670 err = get_compat_flock64(&flock, compat_ptr(arg)); 671 if (err) 672 break; 673 err = fcntl_setlk(fd, f.file, convert_fcntl_cmd(cmd), &flock); 674 break; 675 default: 676 err = do_fcntl(fd, cmd, arg, f.file); 677 break; 678 } 679 out_put: 680 fdput(f); 681 return err; 682 } 683 684 COMPAT_SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd, 685 compat_ulong_t, arg) 686 { 687 return do_compat_fcntl64(fd, cmd, arg); 688 } 689 690 COMPAT_SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, 691 compat_ulong_t, arg) 692 { 693 switch (cmd) { 694 case F_GETLK64: 695 case F_SETLK64: 696 case F_SETLKW64: 697 case F_OFD_GETLK: 698 case F_OFD_SETLK: 699 case F_OFD_SETLKW: 700 return -EINVAL; 701 } 702 return do_compat_fcntl64(fd, cmd, arg); 703 } 704 #endif 705 706 /* Table to convert sigio signal codes into poll band bitmaps */ 707 708 static const __poll_t band_table[NSIGPOLL] = { 709 EPOLLIN | EPOLLRDNORM, /* POLL_IN */ 710 EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND, /* POLL_OUT */ 711 EPOLLIN | EPOLLRDNORM | EPOLLMSG, /* POLL_MSG */ 712 EPOLLERR, /* POLL_ERR */ 713 EPOLLPRI | EPOLLRDBAND, /* POLL_PRI */ 714 EPOLLHUP | EPOLLERR /* POLL_HUP */ 715 }; 716 717 static inline int sigio_perm(struct task_struct *p, 718 struct fown_struct *fown, int sig) 719 { 720 const struct cred *cred; 721 int ret; 722 723 rcu_read_lock(); 724 cred = __task_cred(p); 725 ret = ((uid_eq(fown->euid, GLOBAL_ROOT_UID) || 726 uid_eq(fown->euid, cred->suid) || uid_eq(fown->euid, cred->uid) || 727 uid_eq(fown->uid, cred->suid) || uid_eq(fown->uid, cred->uid)) && 728 !security_file_send_sigiotask(p, fown, sig)); 729 rcu_read_unlock(); 730 return ret; 731 } 732 733 static void send_sigio_to_task(struct task_struct *p, 734 struct fown_struct *fown, 735 int fd, int reason, enum pid_type type) 736 { 737 /* 738 * F_SETSIG can change ->signum lockless in parallel, make 739 * sure we read it once and use the same value throughout. 740 */ 741 int signum = READ_ONCE(fown->signum); 742 743 if (!sigio_perm(p, fown, signum)) 744 return; 745 746 switch (signum) { 747 default: { 748 kernel_siginfo_t si; 749 750 /* Queue a rt signal with the appropriate fd as its 751 value. We use SI_SIGIO as the source, not 752 SI_KERNEL, since kernel signals always get 753 delivered even if we can't queue. Failure to 754 queue in this case _should_ be reported; we fall 755 back to SIGIO in that case. --sct */ 756 clear_siginfo(&si); 757 si.si_signo = signum; 758 si.si_errno = 0; 759 si.si_code = reason; 760 /* 761 * Posix definies POLL_IN and friends to be signal 762 * specific si_codes for SIG_POLL. Linux extended 763 * these si_codes to other signals in a way that is 764 * ambiguous if other signals also have signal 765 * specific si_codes. In that case use SI_SIGIO instead 766 * to remove the ambiguity. 767 */ 768 if ((signum != SIGPOLL) && sig_specific_sicodes(signum)) 769 si.si_code = SI_SIGIO; 770 771 /* Make sure we are called with one of the POLL_* 772 reasons, otherwise we could leak kernel stack into 773 userspace. */ 774 BUG_ON((reason < POLL_IN) || ((reason - POLL_IN) >= NSIGPOLL)); 775 if (reason - POLL_IN >= NSIGPOLL) 776 si.si_band = ~0L; 777 else 778 si.si_band = mangle_poll(band_table[reason - POLL_IN]); 779 si.si_fd = fd; 780 if (!do_send_sig_info(signum, &si, p, type)) 781 break; 782 } 783 fallthrough; /* fall back on the old plain SIGIO signal */ 784 case 0: 785 do_send_sig_info(SIGIO, SEND_SIG_PRIV, p, type); 786 } 787 } 788 789 void send_sigio(struct fown_struct *fown, int fd, int band) 790 { 791 struct task_struct *p; 792 enum pid_type type; 793 unsigned long flags; 794 struct pid *pid; 795 796 read_lock_irqsave(&fown->lock, flags); 797 798 type = fown->pid_type; 799 pid = fown->pid; 800 if (!pid) 801 goto out_unlock_fown; 802 803 if (type <= PIDTYPE_TGID) { 804 rcu_read_lock(); 805 p = pid_task(pid, PIDTYPE_PID); 806 if (p) 807 send_sigio_to_task(p, fown, fd, band, type); 808 rcu_read_unlock(); 809 } else { 810 read_lock(&tasklist_lock); 811 do_each_pid_task(pid, type, p) { 812 send_sigio_to_task(p, fown, fd, band, type); 813 } while_each_pid_task(pid, type, p); 814 read_unlock(&tasklist_lock); 815 } 816 out_unlock_fown: 817 read_unlock_irqrestore(&fown->lock, flags); 818 } 819 820 static void send_sigurg_to_task(struct task_struct *p, 821 struct fown_struct *fown, enum pid_type type) 822 { 823 if (sigio_perm(p, fown, SIGURG)) 824 do_send_sig_info(SIGURG, SEND_SIG_PRIV, p, type); 825 } 826 827 int send_sigurg(struct fown_struct *fown) 828 { 829 struct task_struct *p; 830 enum pid_type type; 831 struct pid *pid; 832 unsigned long flags; 833 int ret = 0; 834 835 read_lock_irqsave(&fown->lock, flags); 836 837 type = fown->pid_type; 838 pid = fown->pid; 839 if (!pid) 840 goto out_unlock_fown; 841 842 ret = 1; 843 844 if (type <= PIDTYPE_TGID) { 845 rcu_read_lock(); 846 p = pid_task(pid, PIDTYPE_PID); 847 if (p) 848 send_sigurg_to_task(p, fown, type); 849 rcu_read_unlock(); 850 } else { 851 read_lock(&tasklist_lock); 852 do_each_pid_task(pid, type, p) { 853 send_sigurg_to_task(p, fown, type); 854 } while_each_pid_task(pid, type, p); 855 read_unlock(&tasklist_lock); 856 } 857 out_unlock_fown: 858 read_unlock_irqrestore(&fown->lock, flags); 859 return ret; 860 } 861 862 static DEFINE_SPINLOCK(fasync_lock); 863 static struct kmem_cache *fasync_cache __ro_after_init; 864 865 /* 866 * Remove a fasync entry. If successfully removed, return 867 * positive and clear the FASYNC flag. If no entry exists, 868 * do nothing and return 0. 869 * 870 * NOTE! It is very important that the FASYNC flag always 871 * match the state "is the filp on a fasync list". 872 * 873 */ 874 int fasync_remove_entry(struct file *filp, struct fasync_struct **fapp) 875 { 876 struct fasync_struct *fa, **fp; 877 int result = 0; 878 879 spin_lock(&filp->f_lock); 880 spin_lock(&fasync_lock); 881 for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) { 882 if (fa->fa_file != filp) 883 continue; 884 885 write_lock_irq(&fa->fa_lock); 886 fa->fa_file = NULL; 887 write_unlock_irq(&fa->fa_lock); 888 889 *fp = fa->fa_next; 890 kfree_rcu(fa, fa_rcu); 891 filp->f_flags &= ~FASYNC; 892 result = 1; 893 break; 894 } 895 spin_unlock(&fasync_lock); 896 spin_unlock(&filp->f_lock); 897 return result; 898 } 899 900 struct fasync_struct *fasync_alloc(void) 901 { 902 return kmem_cache_alloc(fasync_cache, GFP_KERNEL); 903 } 904 905 /* 906 * NOTE! This can be used only for unused fasync entries: 907 * entries that actually got inserted on the fasync list 908 * need to be released by rcu - see fasync_remove_entry. 909 */ 910 void fasync_free(struct fasync_struct *new) 911 { 912 kmem_cache_free(fasync_cache, new); 913 } 914 915 /* 916 * Insert a new entry into the fasync list. Return the pointer to the 917 * old one if we didn't use the new one. 918 * 919 * NOTE! It is very important that the FASYNC flag always 920 * match the state "is the filp on a fasync list". 921 */ 922 struct fasync_struct *fasync_insert_entry(int fd, struct file *filp, struct fasync_struct **fapp, struct fasync_struct *new) 923 { 924 struct fasync_struct *fa, **fp; 925 926 spin_lock(&filp->f_lock); 927 spin_lock(&fasync_lock); 928 for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) { 929 if (fa->fa_file != filp) 930 continue; 931 932 write_lock_irq(&fa->fa_lock); 933 fa->fa_fd = fd; 934 write_unlock_irq(&fa->fa_lock); 935 goto out; 936 } 937 938 rwlock_init(&new->fa_lock); 939 new->magic = FASYNC_MAGIC; 940 new->fa_file = filp; 941 new->fa_fd = fd; 942 new->fa_next = *fapp; 943 rcu_assign_pointer(*fapp, new); 944 filp->f_flags |= FASYNC; 945 946 out: 947 spin_unlock(&fasync_lock); 948 spin_unlock(&filp->f_lock); 949 return fa; 950 } 951 952 /* 953 * Add a fasync entry. Return negative on error, positive if 954 * added, and zero if did nothing but change an existing one. 955 */ 956 static int fasync_add_entry(int fd, struct file *filp, struct fasync_struct **fapp) 957 { 958 struct fasync_struct *new; 959 960 new = fasync_alloc(); 961 if (!new) 962 return -ENOMEM; 963 964 /* 965 * fasync_insert_entry() returns the old (update) entry if 966 * it existed. 967 * 968 * So free the (unused) new entry and return 0 to let the 969 * caller know that we didn't add any new fasync entries. 970 */ 971 if (fasync_insert_entry(fd, filp, fapp, new)) { 972 fasync_free(new); 973 return 0; 974 } 975 976 return 1; 977 } 978 979 /* 980 * fasync_helper() is used by almost all character device drivers 981 * to set up the fasync queue, and for regular files by the file 982 * lease code. It returns negative on error, 0 if it did no changes 983 * and positive if it added/deleted the entry. 984 */ 985 int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp) 986 { 987 if (!on) 988 return fasync_remove_entry(filp, fapp); 989 return fasync_add_entry(fd, filp, fapp); 990 } 991 992 EXPORT_SYMBOL(fasync_helper); 993 994 /* 995 * rcu_read_lock() is held 996 */ 997 static void kill_fasync_rcu(struct fasync_struct *fa, int sig, int band) 998 { 999 while (fa) { 1000 struct fown_struct *fown; 1001 unsigned long flags; 1002 1003 if (fa->magic != FASYNC_MAGIC) { 1004 printk(KERN_ERR "kill_fasync: bad magic number in " 1005 "fasync_struct!\n"); 1006 return; 1007 } 1008 read_lock_irqsave(&fa->fa_lock, flags); 1009 if (fa->fa_file) { 1010 fown = &fa->fa_file->f_owner; 1011 /* Don't send SIGURG to processes which have not set a 1012 queued signum: SIGURG has its own default signalling 1013 mechanism. */ 1014 if (!(sig == SIGURG && fown->signum == 0)) 1015 send_sigio(fown, fa->fa_fd, band); 1016 } 1017 read_unlock_irqrestore(&fa->fa_lock, flags); 1018 fa = rcu_dereference(fa->fa_next); 1019 } 1020 } 1021 1022 void kill_fasync(struct fasync_struct **fp, int sig, int band) 1023 { 1024 /* First a quick test without locking: usually 1025 * the list is empty. 1026 */ 1027 if (*fp) { 1028 rcu_read_lock(); 1029 kill_fasync_rcu(rcu_dereference(*fp), sig, band); 1030 rcu_read_unlock(); 1031 } 1032 } 1033 EXPORT_SYMBOL(kill_fasync); 1034 1035 static int __init fcntl_init(void) 1036 { 1037 /* 1038 * Please add new bits here to ensure allocation uniqueness. 1039 * Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY 1040 * is defined as O_NONBLOCK on some platforms and not on others. 1041 */ 1042 BUILD_BUG_ON(21 - 1 /* for O_RDONLY being 0 */ != 1043 HWEIGHT32( 1044 (VALID_OPEN_FLAGS & ~(O_NONBLOCK | O_NDELAY)) | 1045 __FMODE_EXEC | __FMODE_NONOTIFY)); 1046 1047 fasync_cache = kmem_cache_create("fasync_cache", 1048 sizeof(struct fasync_struct), 0, 1049 SLAB_PANIC | SLAB_ACCOUNT, NULL); 1050 return 0; 1051 } 1052 1053 module_init(fcntl_init) 1054