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