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_FILE_RW_HINT: 295 h = file_write_hint(file); 296 if (copy_to_user(argp, &h, sizeof(*argp))) 297 return -EFAULT; 298 return 0; 299 case F_SET_FILE_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 spin_lock(&file->f_lock); 307 file->f_write_hint = hint; 308 spin_unlock(&file->f_lock); 309 return 0; 310 case F_GET_RW_HINT: 311 h = inode->i_write_hint; 312 if (copy_to_user(argp, &h, sizeof(*argp))) 313 return -EFAULT; 314 return 0; 315 case F_SET_RW_HINT: 316 if (copy_from_user(&h, argp, sizeof(h))) 317 return -EFAULT; 318 hint = (enum rw_hint) h; 319 if (!rw_hint_valid(hint)) 320 return -EINVAL; 321 322 inode_lock(inode); 323 inode->i_write_hint = hint; 324 inode_unlock(inode); 325 return 0; 326 default: 327 return -EINVAL; 328 } 329 } 330 331 static long do_fcntl(int fd, unsigned int cmd, unsigned long arg, 332 struct file *filp) 333 { 334 void __user *argp = (void __user *)arg; 335 struct flock flock; 336 long err = -EINVAL; 337 338 switch (cmd) { 339 case F_DUPFD: 340 err = f_dupfd(arg, filp, 0); 341 break; 342 case F_DUPFD_CLOEXEC: 343 err = f_dupfd(arg, 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, arg & FD_CLOEXEC); 351 break; 352 case F_GETFL: 353 err = filp->f_flags; 354 break; 355 case F_SETFL: 356 err = setfl(fd, filp, arg); 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, arg, 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(arg)) { 410 break; 411 } 412 err = 0; 413 filp->f_owner.signum = arg; 414 break; 415 case F_GETLEASE: 416 err = fcntl_getlease(filp); 417 break; 418 case F_SETLEASE: 419 err = fcntl_setlease(fd, filp, arg); 420 break; 421 case F_NOTIFY: 422 err = fcntl_dirnotify(fd, filp, arg); 423 break; 424 case F_SETPIPE_SZ: 425 case F_GETPIPE_SZ: 426 err = pipe_fcntl(filp, cmd, arg); 427 break; 428 case F_ADD_SEALS: 429 case F_GET_SEALS: 430 err = memfd_fcntl(filp, cmd, arg); 431 break; 432 case F_GET_RW_HINT: 433 case F_SET_RW_HINT: 434 case F_GET_FILE_RW_HINT: 435 case F_SET_FILE_RW_HINT: 436 err = fcntl_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 __read_mostly; 864 865 static void fasync_free_rcu(struct rcu_head *head) 866 { 867 kmem_cache_free(fasync_cache, 868 container_of(head, struct fasync_struct, fa_rcu)); 869 } 870 871 /* 872 * Remove a fasync entry. If successfully removed, return 873 * positive and clear the FASYNC flag. If no entry exists, 874 * do nothing and return 0. 875 * 876 * NOTE! It is very important that the FASYNC flag always 877 * match the state "is the filp on a fasync list". 878 * 879 */ 880 int fasync_remove_entry(struct file *filp, struct fasync_struct **fapp) 881 { 882 struct fasync_struct *fa, **fp; 883 int result = 0; 884 885 spin_lock(&filp->f_lock); 886 spin_lock(&fasync_lock); 887 for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) { 888 if (fa->fa_file != filp) 889 continue; 890 891 write_lock_irq(&fa->fa_lock); 892 fa->fa_file = NULL; 893 write_unlock_irq(&fa->fa_lock); 894 895 *fp = fa->fa_next; 896 call_rcu(&fa->fa_rcu, fasync_free_rcu); 897 filp->f_flags &= ~FASYNC; 898 result = 1; 899 break; 900 } 901 spin_unlock(&fasync_lock); 902 spin_unlock(&filp->f_lock); 903 return result; 904 } 905 906 struct fasync_struct *fasync_alloc(void) 907 { 908 return kmem_cache_alloc(fasync_cache, GFP_KERNEL); 909 } 910 911 /* 912 * NOTE! This can be used only for unused fasync entries: 913 * entries that actually got inserted on the fasync list 914 * need to be released by rcu - see fasync_remove_entry. 915 */ 916 void fasync_free(struct fasync_struct *new) 917 { 918 kmem_cache_free(fasync_cache, new); 919 } 920 921 /* 922 * Insert a new entry into the fasync list. Return the pointer to the 923 * old one if we didn't use the new one. 924 * 925 * NOTE! It is very important that the FASYNC flag always 926 * match the state "is the filp on a fasync list". 927 */ 928 struct fasync_struct *fasync_insert_entry(int fd, struct file *filp, struct fasync_struct **fapp, struct fasync_struct *new) 929 { 930 struct fasync_struct *fa, **fp; 931 932 spin_lock(&filp->f_lock); 933 spin_lock(&fasync_lock); 934 for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) { 935 if (fa->fa_file != filp) 936 continue; 937 938 write_lock_irq(&fa->fa_lock); 939 fa->fa_fd = fd; 940 write_unlock_irq(&fa->fa_lock); 941 goto out; 942 } 943 944 rwlock_init(&new->fa_lock); 945 new->magic = FASYNC_MAGIC; 946 new->fa_file = filp; 947 new->fa_fd = fd; 948 new->fa_next = *fapp; 949 rcu_assign_pointer(*fapp, new); 950 filp->f_flags |= FASYNC; 951 952 out: 953 spin_unlock(&fasync_lock); 954 spin_unlock(&filp->f_lock); 955 return fa; 956 } 957 958 /* 959 * Add a fasync entry. Return negative on error, positive if 960 * added, and zero if did nothing but change an existing one. 961 */ 962 static int fasync_add_entry(int fd, struct file *filp, struct fasync_struct **fapp) 963 { 964 struct fasync_struct *new; 965 966 new = fasync_alloc(); 967 if (!new) 968 return -ENOMEM; 969 970 /* 971 * fasync_insert_entry() returns the old (update) entry if 972 * it existed. 973 * 974 * So free the (unused) new entry and return 0 to let the 975 * caller know that we didn't add any new fasync entries. 976 */ 977 if (fasync_insert_entry(fd, filp, fapp, new)) { 978 fasync_free(new); 979 return 0; 980 } 981 982 return 1; 983 } 984 985 /* 986 * fasync_helper() is used by almost all character device drivers 987 * to set up the fasync queue, and for regular files by the file 988 * lease code. It returns negative on error, 0 if it did no changes 989 * and positive if it added/deleted the entry. 990 */ 991 int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp) 992 { 993 if (!on) 994 return fasync_remove_entry(filp, fapp); 995 return fasync_add_entry(fd, filp, fapp); 996 } 997 998 EXPORT_SYMBOL(fasync_helper); 999 1000 /* 1001 * rcu_read_lock() is held 1002 */ 1003 static void kill_fasync_rcu(struct fasync_struct *fa, int sig, int band) 1004 { 1005 while (fa) { 1006 struct fown_struct *fown; 1007 unsigned long flags; 1008 1009 if (fa->magic != FASYNC_MAGIC) { 1010 printk(KERN_ERR "kill_fasync: bad magic number in " 1011 "fasync_struct!\n"); 1012 return; 1013 } 1014 read_lock_irqsave(&fa->fa_lock, flags); 1015 if (fa->fa_file) { 1016 fown = &fa->fa_file->f_owner; 1017 /* Don't send SIGURG to processes which have not set a 1018 queued signum: SIGURG has its own default signalling 1019 mechanism. */ 1020 if (!(sig == SIGURG && fown->signum == 0)) 1021 send_sigio(fown, fa->fa_fd, band); 1022 } 1023 read_unlock_irqrestore(&fa->fa_lock, flags); 1024 fa = rcu_dereference(fa->fa_next); 1025 } 1026 } 1027 1028 void kill_fasync(struct fasync_struct **fp, int sig, int band) 1029 { 1030 /* First a quick test without locking: usually 1031 * the list is empty. 1032 */ 1033 if (*fp) { 1034 rcu_read_lock(); 1035 kill_fasync_rcu(rcu_dereference(*fp), sig, band); 1036 rcu_read_unlock(); 1037 } 1038 } 1039 EXPORT_SYMBOL(kill_fasync); 1040 1041 static int __init fcntl_init(void) 1042 { 1043 /* 1044 * Please add new bits here to ensure allocation uniqueness. 1045 * Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY 1046 * is defined as O_NONBLOCK on some platforms and not on others. 1047 */ 1048 BUILD_BUG_ON(21 - 1 /* for O_RDONLY being 0 */ != 1049 HWEIGHT32( 1050 (VALID_OPEN_FLAGS & ~(O_NONBLOCK | O_NDELAY)) | 1051 __FMODE_EXEC | __FMODE_NONOTIFY)); 1052 1053 fasync_cache = kmem_cache_create("fasync_cache", 1054 sizeof(struct fasync_struct), 0, 1055 SLAB_PANIC | SLAB_ACCOUNT, NULL); 1056 return 0; 1057 } 1058 1059 module_init(fcntl_init) 1060