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/file.h> 14 #include <linux/fdtable.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 30 #include <linux/poll.h> 31 #include <asm/siginfo.h> 32 #include <linux/uaccess.h> 33 34 #define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT | O_NOATIME) 35 36 static int setfl(int fd, struct file * filp, unsigned long arg) 37 { 38 struct inode * inode = file_inode(filp); 39 int error = 0; 40 41 /* 42 * O_APPEND cannot be cleared if the file is marked as append-only 43 * and the file is open for write. 44 */ 45 if (((arg ^ filp->f_flags) & O_APPEND) && IS_APPEND(inode)) 46 return -EPERM; 47 48 /* O_NOATIME can only be set by the owner or superuser */ 49 if ((arg & O_NOATIME) && !(filp->f_flags & O_NOATIME)) 50 if (!inode_owner_or_capable(file_mnt_user_ns(filp), inode)) 51 return -EPERM; 52 53 /* required for strict SunOS emulation */ 54 if (O_NONBLOCK != O_NDELAY) 55 if (arg & O_NDELAY) 56 arg |= O_NONBLOCK; 57 58 /* Pipe packetized mode is controlled by O_DIRECT flag */ 59 if (!S_ISFIFO(inode->i_mode) && (arg & O_DIRECT)) { 60 if (!filp->f_mapping || !filp->f_mapping->a_ops || 61 !filp->f_mapping->a_ops->direct_IO) 62 return -EINVAL; 63 } 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 spin_unlock(&filp->f_lock); 83 84 out: 85 return error; 86 } 87 88 static void f_modown(struct file *filp, struct pid *pid, enum pid_type type, 89 int force) 90 { 91 write_lock_irq(&filp->f_owner.lock); 92 if (force || !filp->f_owner.pid) { 93 put_pid(filp->f_owner.pid); 94 filp->f_owner.pid = get_pid(pid); 95 filp->f_owner.pid_type = type; 96 97 if (pid) { 98 const struct cred *cred = current_cred(); 99 filp->f_owner.uid = cred->uid; 100 filp->f_owner.euid = cred->euid; 101 } 102 } 103 write_unlock_irq(&filp->f_owner.lock); 104 } 105 106 void __f_setown(struct file *filp, struct pid *pid, enum pid_type type, 107 int force) 108 { 109 security_file_set_fowner(filp); 110 f_modown(filp, pid, type, force); 111 } 112 EXPORT_SYMBOL(__f_setown); 113 114 int f_setown(struct file *filp, unsigned long arg, int force) 115 { 116 enum pid_type type; 117 struct pid *pid = NULL; 118 int who = arg, ret = 0; 119 120 type = PIDTYPE_TGID; 121 if (who < 0) { 122 /* avoid overflow below */ 123 if (who == INT_MIN) 124 return -EINVAL; 125 126 type = PIDTYPE_PGID; 127 who = -who; 128 } 129 130 rcu_read_lock(); 131 if (who) { 132 pid = find_vpid(who); 133 if (!pid) 134 ret = -ESRCH; 135 } 136 137 if (!ret) 138 __f_setown(filp, pid, type, force); 139 rcu_read_unlock(); 140 141 return ret; 142 } 143 EXPORT_SYMBOL(f_setown); 144 145 void f_delown(struct file *filp) 146 { 147 f_modown(filp, NULL, PIDTYPE_TGID, 1); 148 } 149 150 pid_t f_getown(struct file *filp) 151 { 152 pid_t pid = 0; 153 154 read_lock_irq(&filp->f_owner.lock); 155 rcu_read_lock(); 156 if (pid_task(filp->f_owner.pid, filp->f_owner.pid_type)) { 157 pid = pid_vnr(filp->f_owner.pid); 158 if (filp->f_owner.pid_type == PIDTYPE_PGID) 159 pid = -pid; 160 } 161 rcu_read_unlock(); 162 read_unlock_irq(&filp->f_owner.lock); 163 return pid; 164 } 165 166 static int f_setown_ex(struct file *filp, unsigned long arg) 167 { 168 struct f_owner_ex __user *owner_p = (void __user *)arg; 169 struct f_owner_ex owner; 170 struct pid *pid; 171 int type; 172 int ret; 173 174 ret = copy_from_user(&owner, owner_p, sizeof(owner)); 175 if (ret) 176 return -EFAULT; 177 178 switch (owner.type) { 179 case F_OWNER_TID: 180 type = PIDTYPE_PID; 181 break; 182 183 case F_OWNER_PID: 184 type = PIDTYPE_TGID; 185 break; 186 187 case F_OWNER_PGRP: 188 type = PIDTYPE_PGID; 189 break; 190 191 default: 192 return -EINVAL; 193 } 194 195 rcu_read_lock(); 196 pid = find_vpid(owner.pid); 197 if (owner.pid && !pid) 198 ret = -ESRCH; 199 else 200 __f_setown(filp, pid, type, 1); 201 rcu_read_unlock(); 202 203 return ret; 204 } 205 206 static int f_getown_ex(struct file *filp, unsigned long arg) 207 { 208 struct f_owner_ex __user *owner_p = (void __user *)arg; 209 struct f_owner_ex owner = {}; 210 int ret = 0; 211 212 read_lock_irq(&filp->f_owner.lock); 213 rcu_read_lock(); 214 if (pid_task(filp->f_owner.pid, filp->f_owner.pid_type)) 215 owner.pid = pid_vnr(filp->f_owner.pid); 216 rcu_read_unlock(); 217 switch (filp->f_owner.pid_type) { 218 case PIDTYPE_PID: 219 owner.type = F_OWNER_TID; 220 break; 221 222 case PIDTYPE_TGID: 223 owner.type = F_OWNER_PID; 224 break; 225 226 case PIDTYPE_PGID: 227 owner.type = F_OWNER_PGRP; 228 break; 229 230 default: 231 WARN_ON(1); 232 ret = -EINVAL; 233 break; 234 } 235 read_unlock_irq(&filp->f_owner.lock); 236 237 if (!ret) { 238 ret = copy_to_user(owner_p, &owner, sizeof(owner)); 239 if (ret) 240 ret = -EFAULT; 241 } 242 return ret; 243 } 244 245 #ifdef CONFIG_CHECKPOINT_RESTORE 246 static int f_getowner_uids(struct file *filp, unsigned long arg) 247 { 248 struct user_namespace *user_ns = current_user_ns(); 249 uid_t __user *dst = (void __user *)arg; 250 uid_t src[2]; 251 int err; 252 253 read_lock_irq(&filp->f_owner.lock); 254 src[0] = from_kuid(user_ns, filp->f_owner.uid); 255 src[1] = from_kuid(user_ns, filp->f_owner.euid); 256 read_unlock_irq(&filp->f_owner.lock); 257 258 err = put_user(src[0], &dst[0]); 259 err |= put_user(src[1], &dst[1]); 260 261 return err; 262 } 263 #else 264 static int f_getowner_uids(struct file *filp, unsigned long arg) 265 { 266 return -EINVAL; 267 } 268 #endif 269 270 static bool rw_hint_valid(enum rw_hint hint) 271 { 272 switch (hint) { 273 case RWH_WRITE_LIFE_NOT_SET: 274 case RWH_WRITE_LIFE_NONE: 275 case RWH_WRITE_LIFE_SHORT: 276 case RWH_WRITE_LIFE_MEDIUM: 277 case RWH_WRITE_LIFE_LONG: 278 case RWH_WRITE_LIFE_EXTREME: 279 return true; 280 default: 281 return false; 282 } 283 } 284 285 static long fcntl_rw_hint(struct file *file, unsigned int cmd, 286 unsigned long arg) 287 { 288 struct inode *inode = file_inode(file); 289 u64 __user *argp = (u64 __user *)arg; 290 enum rw_hint hint; 291 u64 h; 292 293 switch (cmd) { 294 case F_GET_RW_HINT: 295 h = inode->i_write_hint; 296 if (copy_to_user(argp, &h, sizeof(*argp))) 297 return -EFAULT; 298 return 0; 299 case F_SET_RW_HINT: 300 if (copy_from_user(&h, argp, sizeof(h))) 301 return -EFAULT; 302 hint = (enum rw_hint) h; 303 if (!rw_hint_valid(hint)) 304 return -EINVAL; 305 306 inode_lock(inode); 307 inode->i_write_hint = hint; 308 inode_unlock(inode); 309 return 0; 310 default: 311 return -EINVAL; 312 } 313 } 314 315 static long do_fcntl(int fd, unsigned int cmd, unsigned long arg, 316 struct file *filp) 317 { 318 void __user *argp = (void __user *)arg; 319 struct flock flock; 320 long err = -EINVAL; 321 322 switch (cmd) { 323 case F_DUPFD: 324 err = f_dupfd(arg, filp, 0); 325 break; 326 case F_DUPFD_CLOEXEC: 327 err = f_dupfd(arg, filp, O_CLOEXEC); 328 break; 329 case F_GETFD: 330 err = get_close_on_exec(fd) ? FD_CLOEXEC : 0; 331 break; 332 case F_SETFD: 333 err = 0; 334 set_close_on_exec(fd, arg & FD_CLOEXEC); 335 break; 336 case F_GETFL: 337 err = filp->f_flags; 338 break; 339 case F_SETFL: 340 err = setfl(fd, filp, arg); 341 break; 342 #if BITS_PER_LONG != 32 343 /* 32-bit arches must use fcntl64() */ 344 case F_OFD_GETLK: 345 #endif 346 case F_GETLK: 347 if (copy_from_user(&flock, argp, sizeof(flock))) 348 return -EFAULT; 349 err = fcntl_getlk(filp, cmd, &flock); 350 if (!err && copy_to_user(argp, &flock, sizeof(flock))) 351 return -EFAULT; 352 break; 353 #if BITS_PER_LONG != 32 354 /* 32-bit arches must use fcntl64() */ 355 case F_OFD_SETLK: 356 case F_OFD_SETLKW: 357 fallthrough; 358 #endif 359 case F_SETLK: 360 case F_SETLKW: 361 if (copy_from_user(&flock, argp, sizeof(flock))) 362 return -EFAULT; 363 err = fcntl_setlk(fd, filp, cmd, &flock); 364 break; 365 case F_GETOWN: 366 /* 367 * XXX If f_owner is a process group, the 368 * negative return value will get converted 369 * into an error. Oops. If we keep the 370 * current syscall conventions, the only way 371 * to fix this will be in libc. 372 */ 373 err = f_getown(filp); 374 force_successful_syscall_return(); 375 break; 376 case F_SETOWN: 377 err = f_setown(filp, arg, 1); 378 break; 379 case F_GETOWN_EX: 380 err = f_getown_ex(filp, arg); 381 break; 382 case F_SETOWN_EX: 383 err = f_setown_ex(filp, arg); 384 break; 385 case F_GETOWNER_UIDS: 386 err = f_getowner_uids(filp, arg); 387 break; 388 case F_GETSIG: 389 err = filp->f_owner.signum; 390 break; 391 case F_SETSIG: 392 /* arg == 0 restores default behaviour. */ 393 if (!valid_signal(arg)) { 394 break; 395 } 396 err = 0; 397 filp->f_owner.signum = arg; 398 break; 399 case F_GETLEASE: 400 err = fcntl_getlease(filp); 401 break; 402 case F_SETLEASE: 403 err = fcntl_setlease(fd, filp, arg); 404 break; 405 case F_NOTIFY: 406 err = fcntl_dirnotify(fd, filp, arg); 407 break; 408 case F_SETPIPE_SZ: 409 case F_GETPIPE_SZ: 410 err = pipe_fcntl(filp, cmd, arg); 411 break; 412 case F_ADD_SEALS: 413 case F_GET_SEALS: 414 err = memfd_fcntl(filp, cmd, arg); 415 break; 416 case F_GET_RW_HINT: 417 case F_SET_RW_HINT: 418 err = fcntl_rw_hint(filp, cmd, arg); 419 break; 420 default: 421 break; 422 } 423 return err; 424 } 425 426 static int check_fcntl_cmd(unsigned cmd) 427 { 428 switch (cmd) { 429 case F_DUPFD: 430 case F_DUPFD_CLOEXEC: 431 case F_GETFD: 432 case F_SETFD: 433 case F_GETFL: 434 return 1; 435 } 436 return 0; 437 } 438 439 SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg) 440 { 441 struct fd f = fdget_raw(fd); 442 long err = -EBADF; 443 444 if (!f.file) 445 goto out; 446 447 if (unlikely(f.file->f_mode & FMODE_PATH)) { 448 if (!check_fcntl_cmd(cmd)) 449 goto out1; 450 } 451 452 err = security_file_fcntl(f.file, cmd, arg); 453 if (!err) 454 err = do_fcntl(fd, cmd, arg, f.file); 455 456 out1: 457 fdput(f); 458 out: 459 return err; 460 } 461 462 #if BITS_PER_LONG == 32 463 SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd, 464 unsigned long, arg) 465 { 466 void __user *argp = (void __user *)arg; 467 struct fd f = fdget_raw(fd); 468 struct flock64 flock; 469 long err = -EBADF; 470 471 if (!f.file) 472 goto out; 473 474 if (unlikely(f.file->f_mode & FMODE_PATH)) { 475 if (!check_fcntl_cmd(cmd)) 476 goto out1; 477 } 478 479 err = security_file_fcntl(f.file, cmd, arg); 480 if (err) 481 goto out1; 482 483 switch (cmd) { 484 case F_GETLK64: 485 case F_OFD_GETLK: 486 err = -EFAULT; 487 if (copy_from_user(&flock, argp, sizeof(flock))) 488 break; 489 err = fcntl_getlk64(f.file, cmd, &flock); 490 if (!err && copy_to_user(argp, &flock, sizeof(flock))) 491 err = -EFAULT; 492 break; 493 case F_SETLK64: 494 case F_SETLKW64: 495 case F_OFD_SETLK: 496 case F_OFD_SETLKW: 497 err = -EFAULT; 498 if (copy_from_user(&flock, argp, sizeof(flock))) 499 break; 500 err = fcntl_setlk64(fd, f.file, cmd, &flock); 501 break; 502 default: 503 err = do_fcntl(fd, cmd, arg, f.file); 504 break; 505 } 506 out1: 507 fdput(f); 508 out: 509 return err; 510 } 511 #endif 512 513 #ifdef CONFIG_COMPAT 514 /* careful - don't use anywhere else */ 515 #define copy_flock_fields(dst, src) \ 516 (dst)->l_type = (src)->l_type; \ 517 (dst)->l_whence = (src)->l_whence; \ 518 (dst)->l_start = (src)->l_start; \ 519 (dst)->l_len = (src)->l_len; \ 520 (dst)->l_pid = (src)->l_pid; 521 522 static int get_compat_flock(struct flock *kfl, const struct compat_flock __user *ufl) 523 { 524 struct compat_flock fl; 525 526 if (copy_from_user(&fl, ufl, sizeof(struct compat_flock))) 527 return -EFAULT; 528 copy_flock_fields(kfl, &fl); 529 return 0; 530 } 531 532 static int get_compat_flock64(struct flock *kfl, const struct compat_flock64 __user *ufl) 533 { 534 struct compat_flock64 fl; 535 536 if (copy_from_user(&fl, ufl, sizeof(struct compat_flock64))) 537 return -EFAULT; 538 copy_flock_fields(kfl, &fl); 539 return 0; 540 } 541 542 static int put_compat_flock(const struct flock *kfl, struct compat_flock __user *ufl) 543 { 544 struct compat_flock fl; 545 546 memset(&fl, 0, sizeof(struct compat_flock)); 547 copy_flock_fields(&fl, kfl); 548 if (copy_to_user(ufl, &fl, sizeof(struct compat_flock))) 549 return -EFAULT; 550 return 0; 551 } 552 553 static int put_compat_flock64(const struct flock *kfl, struct compat_flock64 __user *ufl) 554 { 555 struct compat_flock64 fl; 556 557 BUILD_BUG_ON(sizeof(kfl->l_start) > sizeof(ufl->l_start)); 558 BUILD_BUG_ON(sizeof(kfl->l_len) > sizeof(ufl->l_len)); 559 560 memset(&fl, 0, sizeof(struct compat_flock64)); 561 copy_flock_fields(&fl, kfl); 562 if (copy_to_user(ufl, &fl, sizeof(struct compat_flock64))) 563 return -EFAULT; 564 return 0; 565 } 566 #undef copy_flock_fields 567 568 static unsigned int 569 convert_fcntl_cmd(unsigned int cmd) 570 { 571 switch (cmd) { 572 case F_GETLK64: 573 return F_GETLK; 574 case F_SETLK64: 575 return F_SETLK; 576 case F_SETLKW64: 577 return F_SETLKW; 578 } 579 580 return cmd; 581 } 582 583 /* 584 * GETLK was successful and we need to return the data, but it needs to fit in 585 * the compat structure. 586 * l_start shouldn't be too big, unless the original start + end is greater than 587 * COMPAT_OFF_T_MAX, in which case the app was asking for trouble, so we return 588 * -EOVERFLOW in that case. l_len could be too big, in which case we just 589 * truncate it, and only allow the app to see that part of the conflicting lock 590 * that might make sense to it anyway 591 */ 592 static int fixup_compat_flock(struct flock *flock) 593 { 594 if (flock->l_start > COMPAT_OFF_T_MAX) 595 return -EOVERFLOW; 596 if (flock->l_len > COMPAT_OFF_T_MAX) 597 flock->l_len = COMPAT_OFF_T_MAX; 598 return 0; 599 } 600 601 static long do_compat_fcntl64(unsigned int fd, unsigned int cmd, 602 compat_ulong_t arg) 603 { 604 struct fd f = fdget_raw(fd); 605 struct flock flock; 606 long err = -EBADF; 607 608 if (!f.file) 609 return err; 610 611 if (unlikely(f.file->f_mode & FMODE_PATH)) { 612 if (!check_fcntl_cmd(cmd)) 613 goto out_put; 614 } 615 616 err = security_file_fcntl(f.file, cmd, arg); 617 if (err) 618 goto out_put; 619 620 switch (cmd) { 621 case F_GETLK: 622 err = get_compat_flock(&flock, compat_ptr(arg)); 623 if (err) 624 break; 625 err = fcntl_getlk(f.file, convert_fcntl_cmd(cmd), &flock); 626 if (err) 627 break; 628 err = fixup_compat_flock(&flock); 629 if (!err) 630 err = put_compat_flock(&flock, compat_ptr(arg)); 631 break; 632 case F_GETLK64: 633 case F_OFD_GETLK: 634 err = get_compat_flock64(&flock, compat_ptr(arg)); 635 if (err) 636 break; 637 err = fcntl_getlk(f.file, convert_fcntl_cmd(cmd), &flock); 638 if (!err) 639 err = put_compat_flock64(&flock, compat_ptr(arg)); 640 break; 641 case F_SETLK: 642 case F_SETLKW: 643 err = get_compat_flock(&flock, compat_ptr(arg)); 644 if (err) 645 break; 646 err = fcntl_setlk(fd, f.file, convert_fcntl_cmd(cmd), &flock); 647 break; 648 case F_SETLK64: 649 case F_SETLKW64: 650 case F_OFD_SETLK: 651 case F_OFD_SETLKW: 652 err = get_compat_flock64(&flock, compat_ptr(arg)); 653 if (err) 654 break; 655 err = fcntl_setlk(fd, f.file, convert_fcntl_cmd(cmd), &flock); 656 break; 657 default: 658 err = do_fcntl(fd, cmd, arg, f.file); 659 break; 660 } 661 out_put: 662 fdput(f); 663 return err; 664 } 665 666 COMPAT_SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd, 667 compat_ulong_t, arg) 668 { 669 return do_compat_fcntl64(fd, cmd, arg); 670 } 671 672 COMPAT_SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, 673 compat_ulong_t, arg) 674 { 675 switch (cmd) { 676 case F_GETLK64: 677 case F_SETLK64: 678 case F_SETLKW64: 679 case F_OFD_GETLK: 680 case F_OFD_SETLK: 681 case F_OFD_SETLKW: 682 return -EINVAL; 683 } 684 return do_compat_fcntl64(fd, cmd, arg); 685 } 686 #endif 687 688 /* Table to convert sigio signal codes into poll band bitmaps */ 689 690 static const __poll_t band_table[NSIGPOLL] = { 691 EPOLLIN | EPOLLRDNORM, /* POLL_IN */ 692 EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND, /* POLL_OUT */ 693 EPOLLIN | EPOLLRDNORM | EPOLLMSG, /* POLL_MSG */ 694 EPOLLERR, /* POLL_ERR */ 695 EPOLLPRI | EPOLLRDBAND, /* POLL_PRI */ 696 EPOLLHUP | EPOLLERR /* POLL_HUP */ 697 }; 698 699 static inline int sigio_perm(struct task_struct *p, 700 struct fown_struct *fown, int sig) 701 { 702 const struct cred *cred; 703 int ret; 704 705 rcu_read_lock(); 706 cred = __task_cred(p); 707 ret = ((uid_eq(fown->euid, GLOBAL_ROOT_UID) || 708 uid_eq(fown->euid, cred->suid) || uid_eq(fown->euid, cred->uid) || 709 uid_eq(fown->uid, cred->suid) || uid_eq(fown->uid, cred->uid)) && 710 !security_file_send_sigiotask(p, fown, sig)); 711 rcu_read_unlock(); 712 return ret; 713 } 714 715 static void send_sigio_to_task(struct task_struct *p, 716 struct fown_struct *fown, 717 int fd, int reason, enum pid_type type) 718 { 719 /* 720 * F_SETSIG can change ->signum lockless in parallel, make 721 * sure we read it once and use the same value throughout. 722 */ 723 int signum = READ_ONCE(fown->signum); 724 725 if (!sigio_perm(p, fown, signum)) 726 return; 727 728 switch (signum) { 729 default: { 730 kernel_siginfo_t si; 731 732 /* Queue a rt signal with the appropriate fd as its 733 value. We use SI_SIGIO as the source, not 734 SI_KERNEL, since kernel signals always get 735 delivered even if we can't queue. Failure to 736 queue in this case _should_ be reported; we fall 737 back to SIGIO in that case. --sct */ 738 clear_siginfo(&si); 739 si.si_signo = signum; 740 si.si_errno = 0; 741 si.si_code = reason; 742 /* 743 * Posix definies POLL_IN and friends to be signal 744 * specific si_codes for SIG_POLL. Linux extended 745 * these si_codes to other signals in a way that is 746 * ambiguous if other signals also have signal 747 * specific si_codes. In that case use SI_SIGIO instead 748 * to remove the ambiguity. 749 */ 750 if ((signum != SIGPOLL) && sig_specific_sicodes(signum)) 751 si.si_code = SI_SIGIO; 752 753 /* Make sure we are called with one of the POLL_* 754 reasons, otherwise we could leak kernel stack into 755 userspace. */ 756 BUG_ON((reason < POLL_IN) || ((reason - POLL_IN) >= NSIGPOLL)); 757 if (reason - POLL_IN >= NSIGPOLL) 758 si.si_band = ~0L; 759 else 760 si.si_band = mangle_poll(band_table[reason - POLL_IN]); 761 si.si_fd = fd; 762 if (!do_send_sig_info(signum, &si, p, type)) 763 break; 764 } 765 fallthrough; /* fall back on the old plain SIGIO signal */ 766 case 0: 767 do_send_sig_info(SIGIO, SEND_SIG_PRIV, p, type); 768 } 769 } 770 771 void send_sigio(struct fown_struct *fown, int fd, int band) 772 { 773 struct task_struct *p; 774 enum pid_type type; 775 unsigned long flags; 776 struct pid *pid; 777 778 read_lock_irqsave(&fown->lock, flags); 779 780 type = fown->pid_type; 781 pid = fown->pid; 782 if (!pid) 783 goto out_unlock_fown; 784 785 if (type <= PIDTYPE_TGID) { 786 rcu_read_lock(); 787 p = pid_task(pid, PIDTYPE_PID); 788 if (p) 789 send_sigio_to_task(p, fown, fd, band, type); 790 rcu_read_unlock(); 791 } else { 792 read_lock(&tasklist_lock); 793 do_each_pid_task(pid, type, p) { 794 send_sigio_to_task(p, fown, fd, band, type); 795 } while_each_pid_task(pid, type, p); 796 read_unlock(&tasklist_lock); 797 } 798 out_unlock_fown: 799 read_unlock_irqrestore(&fown->lock, flags); 800 } 801 802 static void send_sigurg_to_task(struct task_struct *p, 803 struct fown_struct *fown, enum pid_type type) 804 { 805 if (sigio_perm(p, fown, SIGURG)) 806 do_send_sig_info(SIGURG, SEND_SIG_PRIV, p, type); 807 } 808 809 int send_sigurg(struct fown_struct *fown) 810 { 811 struct task_struct *p; 812 enum pid_type type; 813 struct pid *pid; 814 unsigned long flags; 815 int ret = 0; 816 817 read_lock_irqsave(&fown->lock, flags); 818 819 type = fown->pid_type; 820 pid = fown->pid; 821 if (!pid) 822 goto out_unlock_fown; 823 824 ret = 1; 825 826 if (type <= PIDTYPE_TGID) { 827 rcu_read_lock(); 828 p = pid_task(pid, PIDTYPE_PID); 829 if (p) 830 send_sigurg_to_task(p, fown, type); 831 rcu_read_unlock(); 832 } else { 833 read_lock(&tasklist_lock); 834 do_each_pid_task(pid, type, p) { 835 send_sigurg_to_task(p, fown, type); 836 } while_each_pid_task(pid, type, p); 837 read_unlock(&tasklist_lock); 838 } 839 out_unlock_fown: 840 read_unlock_irqrestore(&fown->lock, flags); 841 return ret; 842 } 843 844 static DEFINE_SPINLOCK(fasync_lock); 845 static struct kmem_cache *fasync_cache __read_mostly; 846 847 static void fasync_free_rcu(struct rcu_head *head) 848 { 849 kmem_cache_free(fasync_cache, 850 container_of(head, struct fasync_struct, fa_rcu)); 851 } 852 853 /* 854 * Remove a fasync entry. If successfully removed, return 855 * positive and clear the FASYNC flag. If no entry exists, 856 * do nothing and return 0. 857 * 858 * NOTE! It is very important that the FASYNC flag always 859 * match the state "is the filp on a fasync list". 860 * 861 */ 862 int fasync_remove_entry(struct file *filp, struct fasync_struct **fapp) 863 { 864 struct fasync_struct *fa, **fp; 865 int result = 0; 866 867 spin_lock(&filp->f_lock); 868 spin_lock(&fasync_lock); 869 for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) { 870 if (fa->fa_file != filp) 871 continue; 872 873 write_lock_irq(&fa->fa_lock); 874 fa->fa_file = NULL; 875 write_unlock_irq(&fa->fa_lock); 876 877 *fp = fa->fa_next; 878 call_rcu(&fa->fa_rcu, fasync_free_rcu); 879 filp->f_flags &= ~FASYNC; 880 result = 1; 881 break; 882 } 883 spin_unlock(&fasync_lock); 884 spin_unlock(&filp->f_lock); 885 return result; 886 } 887 888 struct fasync_struct *fasync_alloc(void) 889 { 890 return kmem_cache_alloc(fasync_cache, GFP_KERNEL); 891 } 892 893 /* 894 * NOTE! This can be used only for unused fasync entries: 895 * entries that actually got inserted on the fasync list 896 * need to be released by rcu - see fasync_remove_entry. 897 */ 898 void fasync_free(struct fasync_struct *new) 899 { 900 kmem_cache_free(fasync_cache, new); 901 } 902 903 /* 904 * Insert a new entry into the fasync list. Return the pointer to the 905 * old one if we didn't use the new one. 906 * 907 * NOTE! It is very important that the FASYNC flag always 908 * match the state "is the filp on a fasync list". 909 */ 910 struct fasync_struct *fasync_insert_entry(int fd, struct file *filp, struct fasync_struct **fapp, struct fasync_struct *new) 911 { 912 struct fasync_struct *fa, **fp; 913 914 spin_lock(&filp->f_lock); 915 spin_lock(&fasync_lock); 916 for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) { 917 if (fa->fa_file != filp) 918 continue; 919 920 write_lock_irq(&fa->fa_lock); 921 fa->fa_fd = fd; 922 write_unlock_irq(&fa->fa_lock); 923 goto out; 924 } 925 926 rwlock_init(&new->fa_lock); 927 new->magic = FASYNC_MAGIC; 928 new->fa_file = filp; 929 new->fa_fd = fd; 930 new->fa_next = *fapp; 931 rcu_assign_pointer(*fapp, new); 932 filp->f_flags |= FASYNC; 933 934 out: 935 spin_unlock(&fasync_lock); 936 spin_unlock(&filp->f_lock); 937 return fa; 938 } 939 940 /* 941 * Add a fasync entry. Return negative on error, positive if 942 * added, and zero if did nothing but change an existing one. 943 */ 944 static int fasync_add_entry(int fd, struct file *filp, struct fasync_struct **fapp) 945 { 946 struct fasync_struct *new; 947 948 new = fasync_alloc(); 949 if (!new) 950 return -ENOMEM; 951 952 /* 953 * fasync_insert_entry() returns the old (update) entry if 954 * it existed. 955 * 956 * So free the (unused) new entry and return 0 to let the 957 * caller know that we didn't add any new fasync entries. 958 */ 959 if (fasync_insert_entry(fd, filp, fapp, new)) { 960 fasync_free(new); 961 return 0; 962 } 963 964 return 1; 965 } 966 967 /* 968 * fasync_helper() is used by almost all character device drivers 969 * to set up the fasync queue, and for regular files by the file 970 * lease code. It returns negative on error, 0 if it did no changes 971 * and positive if it added/deleted the entry. 972 */ 973 int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp) 974 { 975 if (!on) 976 return fasync_remove_entry(filp, fapp); 977 return fasync_add_entry(fd, filp, fapp); 978 } 979 980 EXPORT_SYMBOL(fasync_helper); 981 982 /* 983 * rcu_read_lock() is held 984 */ 985 static void kill_fasync_rcu(struct fasync_struct *fa, int sig, int band) 986 { 987 while (fa) { 988 struct fown_struct *fown; 989 unsigned long flags; 990 991 if (fa->magic != FASYNC_MAGIC) { 992 printk(KERN_ERR "kill_fasync: bad magic number in " 993 "fasync_struct!\n"); 994 return; 995 } 996 read_lock_irqsave(&fa->fa_lock, flags); 997 if (fa->fa_file) { 998 fown = &fa->fa_file->f_owner; 999 /* Don't send SIGURG to processes which have not set a 1000 queued signum: SIGURG has its own default signalling 1001 mechanism. */ 1002 if (!(sig == SIGURG && fown->signum == 0)) 1003 send_sigio(fown, fa->fa_fd, band); 1004 } 1005 read_unlock_irqrestore(&fa->fa_lock, flags); 1006 fa = rcu_dereference(fa->fa_next); 1007 } 1008 } 1009 1010 void kill_fasync(struct fasync_struct **fp, int sig, int band) 1011 { 1012 /* First a quick test without locking: usually 1013 * the list is empty. 1014 */ 1015 if (*fp) { 1016 rcu_read_lock(); 1017 kill_fasync_rcu(rcu_dereference(*fp), sig, band); 1018 rcu_read_unlock(); 1019 } 1020 } 1021 EXPORT_SYMBOL(kill_fasync); 1022 1023 static int __init fcntl_init(void) 1024 { 1025 /* 1026 * Please add new bits here to ensure allocation uniqueness. 1027 * Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY 1028 * is defined as O_NONBLOCK on some platforms and not on others. 1029 */ 1030 BUILD_BUG_ON(21 - 1 /* for O_RDONLY being 0 */ != 1031 HWEIGHT32( 1032 (VALID_OPEN_FLAGS & ~(O_NONBLOCK | O_NDELAY)) | 1033 __FMODE_EXEC | __FMODE_NONOTIFY)); 1034 1035 fasync_cache = kmem_cache_create("fasync_cache", 1036 sizeof(struct fasync_struct), 0, 1037 SLAB_PANIC | SLAB_ACCOUNT, NULL); 1038 return 0; 1039 } 1040 1041 module_init(fcntl_init) 1042