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 read_lock(&filp->f_owner.lock); 154 rcu_read_lock(); 155 if (pid_task(filp->f_owner.pid, filp->f_owner.pid_type)) { 156 pid = pid_vnr(filp->f_owner.pid); 157 if (filp->f_owner.pid_type == PIDTYPE_PGID) 158 pid = -pid; 159 } 160 rcu_read_unlock(); 161 read_unlock(&filp->f_owner.lock); 162 return pid; 163 } 164 165 static int f_setown_ex(struct file *filp, unsigned long arg) 166 { 167 struct f_owner_ex __user *owner_p = (void __user *)arg; 168 struct f_owner_ex owner; 169 struct pid *pid; 170 int type; 171 int ret; 172 173 ret = copy_from_user(&owner, owner_p, sizeof(owner)); 174 if (ret) 175 return -EFAULT; 176 177 switch (owner.type) { 178 case F_OWNER_TID: 179 type = PIDTYPE_PID; 180 break; 181 182 case F_OWNER_PID: 183 type = PIDTYPE_TGID; 184 break; 185 186 case F_OWNER_PGRP: 187 type = PIDTYPE_PGID; 188 break; 189 190 default: 191 return -EINVAL; 192 } 193 194 rcu_read_lock(); 195 pid = find_vpid(owner.pid); 196 if (owner.pid && !pid) 197 ret = -ESRCH; 198 else 199 __f_setown(filp, pid, type, 1); 200 rcu_read_unlock(); 201 202 return ret; 203 } 204 205 static int f_getown_ex(struct file *filp, unsigned long arg) 206 { 207 struct f_owner_ex __user *owner_p = (void __user *)arg; 208 struct f_owner_ex owner = {}; 209 int ret = 0; 210 211 read_lock(&filp->f_owner.lock); 212 rcu_read_lock(); 213 if (pid_task(filp->f_owner.pid, filp->f_owner.pid_type)) 214 owner.pid = pid_vnr(filp->f_owner.pid); 215 rcu_read_unlock(); 216 switch (filp->f_owner.pid_type) { 217 case PIDTYPE_PID: 218 owner.type = F_OWNER_TID; 219 break; 220 221 case PIDTYPE_TGID: 222 owner.type = F_OWNER_PID; 223 break; 224 225 case PIDTYPE_PGID: 226 owner.type = F_OWNER_PGRP; 227 break; 228 229 default: 230 WARN_ON(1); 231 ret = -EINVAL; 232 break; 233 } 234 read_unlock(&filp->f_owner.lock); 235 236 if (!ret) { 237 ret = copy_to_user(owner_p, &owner, sizeof(owner)); 238 if (ret) 239 ret = -EFAULT; 240 } 241 return ret; 242 } 243 244 #ifdef CONFIG_CHECKPOINT_RESTORE 245 static int f_getowner_uids(struct file *filp, unsigned long arg) 246 { 247 struct user_namespace *user_ns = current_user_ns(); 248 uid_t __user *dst = (void __user *)arg; 249 uid_t src[2]; 250 int err; 251 252 read_lock(&filp->f_owner.lock); 253 src[0] = from_kuid(user_ns, filp->f_owner.uid); 254 src[1] = from_kuid(user_ns, filp->f_owner.euid); 255 read_unlock(&filp->f_owner.lock); 256 257 err = put_user(src[0], &dst[0]); 258 err |= put_user(src[1], &dst[1]); 259 260 return err; 261 } 262 #else 263 static int f_getowner_uids(struct file *filp, unsigned long arg) 264 { 265 return -EINVAL; 266 } 267 #endif 268 269 static bool rw_hint_valid(enum rw_hint hint) 270 { 271 switch (hint) { 272 case RWH_WRITE_LIFE_NOT_SET: 273 case RWH_WRITE_LIFE_NONE: 274 case RWH_WRITE_LIFE_SHORT: 275 case RWH_WRITE_LIFE_MEDIUM: 276 case RWH_WRITE_LIFE_LONG: 277 case RWH_WRITE_LIFE_EXTREME: 278 return true; 279 default: 280 return false; 281 } 282 } 283 284 static long fcntl_rw_hint(struct file *file, unsigned int cmd, 285 unsigned long arg) 286 { 287 struct inode *inode = file_inode(file); 288 u64 __user *argp = (u64 __user *)arg; 289 enum rw_hint hint; 290 u64 h; 291 292 switch (cmd) { 293 case F_GET_FILE_RW_HINT: 294 h = file_write_hint(file); 295 if (copy_to_user(argp, &h, sizeof(*argp))) 296 return -EFAULT; 297 return 0; 298 case F_SET_FILE_RW_HINT: 299 if (copy_from_user(&h, argp, sizeof(h))) 300 return -EFAULT; 301 hint = (enum rw_hint) h; 302 if (!rw_hint_valid(hint)) 303 return -EINVAL; 304 305 spin_lock(&file->f_lock); 306 file->f_write_hint = hint; 307 spin_unlock(&file->f_lock); 308 return 0; 309 case F_GET_RW_HINT: 310 h = inode->i_write_hint; 311 if (copy_to_user(argp, &h, sizeof(*argp))) 312 return -EFAULT; 313 return 0; 314 case F_SET_RW_HINT: 315 if (copy_from_user(&h, argp, sizeof(h))) 316 return -EFAULT; 317 hint = (enum rw_hint) h; 318 if (!rw_hint_valid(hint)) 319 return -EINVAL; 320 321 inode_lock(inode); 322 inode->i_write_hint = hint; 323 inode_unlock(inode); 324 return 0; 325 default: 326 return -EINVAL; 327 } 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 struct flock flock; 335 long err = -EINVAL; 336 337 switch (cmd) { 338 case F_DUPFD: 339 err = f_dupfd(arg, filp, 0); 340 break; 341 case F_DUPFD_CLOEXEC: 342 err = f_dupfd(arg, filp, O_CLOEXEC); 343 break; 344 case F_GETFD: 345 err = get_close_on_exec(fd) ? FD_CLOEXEC : 0; 346 break; 347 case F_SETFD: 348 err = 0; 349 set_close_on_exec(fd, arg & FD_CLOEXEC); 350 break; 351 case F_GETFL: 352 err = filp->f_flags; 353 break; 354 case F_SETFL: 355 err = setfl(fd, filp, arg); 356 break; 357 #if BITS_PER_LONG != 32 358 /* 32-bit arches must use fcntl64() */ 359 case F_OFD_GETLK: 360 #endif 361 case F_GETLK: 362 if (copy_from_user(&flock, argp, sizeof(flock))) 363 return -EFAULT; 364 err = fcntl_getlk(filp, cmd, &flock); 365 if (!err && copy_to_user(argp, &flock, sizeof(flock))) 366 return -EFAULT; 367 break; 368 #if BITS_PER_LONG != 32 369 /* 32-bit arches must use fcntl64() */ 370 case F_OFD_SETLK: 371 case F_OFD_SETLKW: 372 #endif 373 fallthrough; 374 case F_SETLK: 375 case F_SETLKW: 376 if (copy_from_user(&flock, argp, sizeof(flock))) 377 return -EFAULT; 378 err = fcntl_setlk(fd, filp, cmd, &flock); 379 break; 380 case F_GETOWN: 381 /* 382 * XXX If f_owner is a process group, the 383 * negative return value will get converted 384 * into an error. Oops. If we keep the 385 * current syscall conventions, the only way 386 * to fix this will be in libc. 387 */ 388 err = f_getown(filp); 389 force_successful_syscall_return(); 390 break; 391 case F_SETOWN: 392 err = f_setown(filp, arg, 1); 393 break; 394 case F_GETOWN_EX: 395 err = f_getown_ex(filp, arg); 396 break; 397 case F_SETOWN_EX: 398 err = f_setown_ex(filp, arg); 399 break; 400 case F_GETOWNER_UIDS: 401 err = f_getowner_uids(filp, arg); 402 break; 403 case F_GETSIG: 404 err = filp->f_owner.signum; 405 break; 406 case F_SETSIG: 407 /* arg == 0 restores default behaviour. */ 408 if (!valid_signal(arg)) { 409 break; 410 } 411 err = 0; 412 filp->f_owner.signum = arg; 413 break; 414 case F_GETLEASE: 415 err = fcntl_getlease(filp); 416 break; 417 case F_SETLEASE: 418 err = fcntl_setlease(fd, filp, arg); 419 break; 420 case F_NOTIFY: 421 err = fcntl_dirnotify(fd, filp, arg); 422 break; 423 case F_SETPIPE_SZ: 424 case F_GETPIPE_SZ: 425 err = pipe_fcntl(filp, cmd, arg); 426 break; 427 case F_ADD_SEALS: 428 case F_GET_SEALS: 429 err = memfd_fcntl(filp, cmd, arg); 430 break; 431 case F_GET_RW_HINT: 432 case F_SET_RW_HINT: 433 case F_GET_FILE_RW_HINT: 434 case F_SET_FILE_RW_HINT: 435 err = fcntl_rw_hint(filp, cmd, arg); 436 break; 437 default: 438 break; 439 } 440 return err; 441 } 442 443 static int check_fcntl_cmd(unsigned cmd) 444 { 445 switch (cmd) { 446 case F_DUPFD: 447 case F_DUPFD_CLOEXEC: 448 case F_GETFD: 449 case F_SETFD: 450 case F_GETFL: 451 return 1; 452 } 453 return 0; 454 } 455 456 SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg) 457 { 458 struct fd f = fdget_raw(fd); 459 long err = -EBADF; 460 461 if (!f.file) 462 goto out; 463 464 if (unlikely(f.file->f_mode & FMODE_PATH)) { 465 if (!check_fcntl_cmd(cmd)) 466 goto out1; 467 } 468 469 err = security_file_fcntl(f.file, cmd, arg); 470 if (!err) 471 err = do_fcntl(fd, cmd, arg, f.file); 472 473 out1: 474 fdput(f); 475 out: 476 return err; 477 } 478 479 #if BITS_PER_LONG == 32 480 SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd, 481 unsigned long, arg) 482 { 483 void __user *argp = (void __user *)arg; 484 struct fd f = fdget_raw(fd); 485 struct flock64 flock; 486 long err = -EBADF; 487 488 if (!f.file) 489 goto out; 490 491 if (unlikely(f.file->f_mode & FMODE_PATH)) { 492 if (!check_fcntl_cmd(cmd)) 493 goto out1; 494 } 495 496 err = security_file_fcntl(f.file, cmd, arg); 497 if (err) 498 goto out1; 499 500 switch (cmd) { 501 case F_GETLK64: 502 case F_OFD_GETLK: 503 err = -EFAULT; 504 if (copy_from_user(&flock, argp, sizeof(flock))) 505 break; 506 err = fcntl_getlk64(f.file, cmd, &flock); 507 if (!err && copy_to_user(argp, &flock, sizeof(flock))) 508 err = -EFAULT; 509 break; 510 case F_SETLK64: 511 case F_SETLKW64: 512 case F_OFD_SETLK: 513 case F_OFD_SETLKW: 514 err = -EFAULT; 515 if (copy_from_user(&flock, argp, sizeof(flock))) 516 break; 517 err = fcntl_setlk64(fd, f.file, cmd, &flock); 518 break; 519 default: 520 err = do_fcntl(fd, cmd, arg, f.file); 521 break; 522 } 523 out1: 524 fdput(f); 525 out: 526 return err; 527 } 528 #endif 529 530 #ifdef CONFIG_COMPAT 531 /* careful - don't use anywhere else */ 532 #define copy_flock_fields(dst, src) \ 533 (dst)->l_type = (src)->l_type; \ 534 (dst)->l_whence = (src)->l_whence; \ 535 (dst)->l_start = (src)->l_start; \ 536 (dst)->l_len = (src)->l_len; \ 537 (dst)->l_pid = (src)->l_pid; 538 539 static int get_compat_flock(struct flock *kfl, const struct compat_flock __user *ufl) 540 { 541 struct compat_flock fl; 542 543 if (copy_from_user(&fl, ufl, sizeof(struct compat_flock))) 544 return -EFAULT; 545 copy_flock_fields(kfl, &fl); 546 return 0; 547 } 548 549 static int get_compat_flock64(struct flock *kfl, const struct compat_flock64 __user *ufl) 550 { 551 struct compat_flock64 fl; 552 553 if (copy_from_user(&fl, ufl, sizeof(struct compat_flock64))) 554 return -EFAULT; 555 copy_flock_fields(kfl, &fl); 556 return 0; 557 } 558 559 static int put_compat_flock(const struct flock *kfl, struct compat_flock __user *ufl) 560 { 561 struct compat_flock fl; 562 563 memset(&fl, 0, sizeof(struct compat_flock)); 564 copy_flock_fields(&fl, kfl); 565 if (copy_to_user(ufl, &fl, sizeof(struct compat_flock))) 566 return -EFAULT; 567 return 0; 568 } 569 570 static int put_compat_flock64(const struct flock *kfl, struct compat_flock64 __user *ufl) 571 { 572 struct compat_flock64 fl; 573 574 BUILD_BUG_ON(sizeof(kfl->l_start) > sizeof(ufl->l_start)); 575 BUILD_BUG_ON(sizeof(kfl->l_len) > sizeof(ufl->l_len)); 576 577 memset(&fl, 0, sizeof(struct compat_flock64)); 578 copy_flock_fields(&fl, kfl); 579 if (copy_to_user(ufl, &fl, sizeof(struct compat_flock64))) 580 return -EFAULT; 581 return 0; 582 } 583 #undef copy_flock_fields 584 585 static unsigned int 586 convert_fcntl_cmd(unsigned int cmd) 587 { 588 switch (cmd) { 589 case F_GETLK64: 590 return F_GETLK; 591 case F_SETLK64: 592 return F_SETLK; 593 case F_SETLKW64: 594 return F_SETLKW; 595 } 596 597 return cmd; 598 } 599 600 /* 601 * GETLK was successful and we need to return the data, but it needs to fit in 602 * the compat structure. 603 * l_start shouldn't be too big, unless the original start + end is greater than 604 * COMPAT_OFF_T_MAX, in which case the app was asking for trouble, so we return 605 * -EOVERFLOW in that case. l_len could be too big, in which case we just 606 * truncate it, and only allow the app to see that part of the conflicting lock 607 * that might make sense to it anyway 608 */ 609 static int fixup_compat_flock(struct flock *flock) 610 { 611 if (flock->l_start > COMPAT_OFF_T_MAX) 612 return -EOVERFLOW; 613 if (flock->l_len > COMPAT_OFF_T_MAX) 614 flock->l_len = COMPAT_OFF_T_MAX; 615 return 0; 616 } 617 618 static long do_compat_fcntl64(unsigned int fd, unsigned int cmd, 619 compat_ulong_t arg) 620 { 621 struct fd f = fdget_raw(fd); 622 struct flock flock; 623 long err = -EBADF; 624 625 if (!f.file) 626 return err; 627 628 if (unlikely(f.file->f_mode & FMODE_PATH)) { 629 if (!check_fcntl_cmd(cmd)) 630 goto out_put; 631 } 632 633 err = security_file_fcntl(f.file, cmd, arg); 634 if (err) 635 goto out_put; 636 637 switch (cmd) { 638 case F_GETLK: 639 err = get_compat_flock(&flock, compat_ptr(arg)); 640 if (err) 641 break; 642 err = fcntl_getlk(f.file, convert_fcntl_cmd(cmd), &flock); 643 if (err) 644 break; 645 err = fixup_compat_flock(&flock); 646 if (!err) 647 err = put_compat_flock(&flock, compat_ptr(arg)); 648 break; 649 case F_GETLK64: 650 case F_OFD_GETLK: 651 err = get_compat_flock64(&flock, compat_ptr(arg)); 652 if (err) 653 break; 654 err = fcntl_getlk(f.file, convert_fcntl_cmd(cmd), &flock); 655 if (!err) 656 err = put_compat_flock64(&flock, compat_ptr(arg)); 657 break; 658 case F_SETLK: 659 case F_SETLKW: 660 err = get_compat_flock(&flock, compat_ptr(arg)); 661 if (err) 662 break; 663 err = fcntl_setlk(fd, f.file, convert_fcntl_cmd(cmd), &flock); 664 break; 665 case F_SETLK64: 666 case F_SETLKW64: 667 case F_OFD_SETLK: 668 case F_OFD_SETLKW: 669 err = get_compat_flock64(&flock, compat_ptr(arg)); 670 if (err) 671 break; 672 err = fcntl_setlk(fd, f.file, convert_fcntl_cmd(cmd), &flock); 673 break; 674 default: 675 err = do_fcntl(fd, cmd, arg, f.file); 676 break; 677 } 678 out_put: 679 fdput(f); 680 return err; 681 } 682 683 COMPAT_SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd, 684 compat_ulong_t, arg) 685 { 686 return do_compat_fcntl64(fd, cmd, arg); 687 } 688 689 COMPAT_SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, 690 compat_ulong_t, arg) 691 { 692 switch (cmd) { 693 case F_GETLK64: 694 case F_SETLK64: 695 case F_SETLKW64: 696 case F_OFD_GETLK: 697 case F_OFD_SETLK: 698 case F_OFD_SETLKW: 699 return -EINVAL; 700 } 701 return do_compat_fcntl64(fd, cmd, arg); 702 } 703 #endif 704 705 /* Table to convert sigio signal codes into poll band bitmaps */ 706 707 static const __poll_t band_table[NSIGPOLL] = { 708 EPOLLIN | EPOLLRDNORM, /* POLL_IN */ 709 EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND, /* POLL_OUT */ 710 EPOLLIN | EPOLLRDNORM | EPOLLMSG, /* POLL_MSG */ 711 EPOLLERR, /* POLL_ERR */ 712 EPOLLPRI | EPOLLRDBAND, /* POLL_PRI */ 713 EPOLLHUP | EPOLLERR /* POLL_HUP */ 714 }; 715 716 static inline int sigio_perm(struct task_struct *p, 717 struct fown_struct *fown, int sig) 718 { 719 const struct cred *cred; 720 int ret; 721 722 rcu_read_lock(); 723 cred = __task_cred(p); 724 ret = ((uid_eq(fown->euid, GLOBAL_ROOT_UID) || 725 uid_eq(fown->euid, cred->suid) || uid_eq(fown->euid, cred->uid) || 726 uid_eq(fown->uid, cred->suid) || uid_eq(fown->uid, cred->uid)) && 727 !security_file_send_sigiotask(p, fown, sig)); 728 rcu_read_unlock(); 729 return ret; 730 } 731 732 static void send_sigio_to_task(struct task_struct *p, 733 struct fown_struct *fown, 734 int fd, int reason, enum pid_type type) 735 { 736 /* 737 * F_SETSIG can change ->signum lockless in parallel, make 738 * sure we read it once and use the same value throughout. 739 */ 740 int signum = READ_ONCE(fown->signum); 741 742 if (!sigio_perm(p, fown, signum)) 743 return; 744 745 switch (signum) { 746 default: { 747 kernel_siginfo_t si; 748 749 /* Queue a rt signal with the appropriate fd as its 750 value. We use SI_SIGIO as the source, not 751 SI_KERNEL, since kernel signals always get 752 delivered even if we can't queue. Failure to 753 queue in this case _should_ be reported; we fall 754 back to SIGIO in that case. --sct */ 755 clear_siginfo(&si); 756 si.si_signo = signum; 757 si.si_errno = 0; 758 si.si_code = reason; 759 /* 760 * Posix definies POLL_IN and friends to be signal 761 * specific si_codes for SIG_POLL. Linux extended 762 * these si_codes to other signals in a way that is 763 * ambiguous if other signals also have signal 764 * specific si_codes. In that case use SI_SIGIO instead 765 * to remove the ambiguity. 766 */ 767 if ((signum != SIGPOLL) && sig_specific_sicodes(signum)) 768 si.si_code = SI_SIGIO; 769 770 /* Make sure we are called with one of the POLL_* 771 reasons, otherwise we could leak kernel stack into 772 userspace. */ 773 BUG_ON((reason < POLL_IN) || ((reason - POLL_IN) >= NSIGPOLL)); 774 if (reason - POLL_IN >= NSIGPOLL) 775 si.si_band = ~0L; 776 else 777 si.si_band = mangle_poll(band_table[reason - POLL_IN]); 778 si.si_fd = fd; 779 if (!do_send_sig_info(signum, &si, p, type)) 780 break; 781 } 782 fallthrough; /* fall back on the old plain SIGIO signal */ 783 case 0: 784 do_send_sig_info(SIGIO, SEND_SIG_PRIV, p, type); 785 } 786 } 787 788 void send_sigio(struct fown_struct *fown, int fd, int band) 789 { 790 struct task_struct *p; 791 enum pid_type type; 792 unsigned long flags; 793 struct pid *pid; 794 795 read_lock_irqsave(&fown->lock, flags); 796 797 type = fown->pid_type; 798 pid = fown->pid; 799 if (!pid) 800 goto out_unlock_fown; 801 802 if (type <= PIDTYPE_TGID) { 803 rcu_read_lock(); 804 p = pid_task(pid, PIDTYPE_PID); 805 if (p) 806 send_sigio_to_task(p, fown, fd, band, type); 807 rcu_read_unlock(); 808 } else { 809 read_lock(&tasklist_lock); 810 do_each_pid_task(pid, type, p) { 811 send_sigio_to_task(p, fown, fd, band, type); 812 } while_each_pid_task(pid, type, p); 813 read_unlock(&tasklist_lock); 814 } 815 out_unlock_fown: 816 read_unlock_irqrestore(&fown->lock, flags); 817 } 818 819 static void send_sigurg_to_task(struct task_struct *p, 820 struct fown_struct *fown, enum pid_type type) 821 { 822 if (sigio_perm(p, fown, SIGURG)) 823 do_send_sig_info(SIGURG, SEND_SIG_PRIV, p, type); 824 } 825 826 int send_sigurg(struct fown_struct *fown) 827 { 828 struct task_struct *p; 829 enum pid_type type; 830 struct pid *pid; 831 unsigned long flags; 832 int ret = 0; 833 834 read_lock_irqsave(&fown->lock, flags); 835 836 type = fown->pid_type; 837 pid = fown->pid; 838 if (!pid) 839 goto out_unlock_fown; 840 841 ret = 1; 842 843 if (type <= PIDTYPE_TGID) { 844 rcu_read_lock(); 845 p = pid_task(pid, PIDTYPE_PID); 846 if (p) 847 send_sigurg_to_task(p, fown, type); 848 rcu_read_unlock(); 849 } else { 850 read_lock(&tasklist_lock); 851 do_each_pid_task(pid, type, p) { 852 send_sigurg_to_task(p, fown, type); 853 } while_each_pid_task(pid, type, p); 854 read_unlock(&tasklist_lock); 855 } 856 out_unlock_fown: 857 read_unlock_irqrestore(&fown->lock, flags); 858 return ret; 859 } 860 861 static DEFINE_SPINLOCK(fasync_lock); 862 static struct kmem_cache *fasync_cache __read_mostly; 863 864 static void fasync_free_rcu(struct rcu_head *head) 865 { 866 kmem_cache_free(fasync_cache, 867 container_of(head, struct fasync_struct, fa_rcu)); 868 } 869 870 /* 871 * Remove a fasync entry. If successfully removed, return 872 * positive and clear the FASYNC flag. If no entry exists, 873 * do nothing and return 0. 874 * 875 * NOTE! It is very important that the FASYNC flag always 876 * match the state "is the filp on a fasync list". 877 * 878 */ 879 int fasync_remove_entry(struct file *filp, struct fasync_struct **fapp) 880 { 881 struct fasync_struct *fa, **fp; 882 int result = 0; 883 884 spin_lock(&filp->f_lock); 885 spin_lock(&fasync_lock); 886 for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) { 887 if (fa->fa_file != filp) 888 continue; 889 890 write_lock_irq(&fa->fa_lock); 891 fa->fa_file = NULL; 892 write_unlock_irq(&fa->fa_lock); 893 894 *fp = fa->fa_next; 895 call_rcu(&fa->fa_rcu, fasync_free_rcu); 896 filp->f_flags &= ~FASYNC; 897 result = 1; 898 break; 899 } 900 spin_unlock(&fasync_lock); 901 spin_unlock(&filp->f_lock); 902 return result; 903 } 904 905 struct fasync_struct *fasync_alloc(void) 906 { 907 return kmem_cache_alloc(fasync_cache, GFP_KERNEL); 908 } 909 910 /* 911 * NOTE! This can be used only for unused fasync entries: 912 * entries that actually got inserted on the fasync list 913 * need to be released by rcu - see fasync_remove_entry. 914 */ 915 void fasync_free(struct fasync_struct *new) 916 { 917 kmem_cache_free(fasync_cache, new); 918 } 919 920 /* 921 * Insert a new entry into the fasync list. Return the pointer to the 922 * old one if we didn't use the new one. 923 * 924 * NOTE! It is very important that the FASYNC flag always 925 * match the state "is the filp on a fasync list". 926 */ 927 struct fasync_struct *fasync_insert_entry(int fd, struct file *filp, struct fasync_struct **fapp, struct fasync_struct *new) 928 { 929 struct fasync_struct *fa, **fp; 930 931 spin_lock(&filp->f_lock); 932 spin_lock(&fasync_lock); 933 for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) { 934 if (fa->fa_file != filp) 935 continue; 936 937 write_lock_irq(&fa->fa_lock); 938 fa->fa_fd = fd; 939 write_unlock_irq(&fa->fa_lock); 940 goto out; 941 } 942 943 rwlock_init(&new->fa_lock); 944 new->magic = FASYNC_MAGIC; 945 new->fa_file = filp; 946 new->fa_fd = fd; 947 new->fa_next = *fapp; 948 rcu_assign_pointer(*fapp, new); 949 filp->f_flags |= FASYNC; 950 951 out: 952 spin_unlock(&fasync_lock); 953 spin_unlock(&filp->f_lock); 954 return fa; 955 } 956 957 /* 958 * Add a fasync entry. Return negative on error, positive if 959 * added, and zero if did nothing but change an existing one. 960 */ 961 static int fasync_add_entry(int fd, struct file *filp, struct fasync_struct **fapp) 962 { 963 struct fasync_struct *new; 964 965 new = fasync_alloc(); 966 if (!new) 967 return -ENOMEM; 968 969 /* 970 * fasync_insert_entry() returns the old (update) entry if 971 * it existed. 972 * 973 * So free the (unused) new entry and return 0 to let the 974 * caller know that we didn't add any new fasync entries. 975 */ 976 if (fasync_insert_entry(fd, filp, fapp, new)) { 977 fasync_free(new); 978 return 0; 979 } 980 981 return 1; 982 } 983 984 /* 985 * fasync_helper() is used by almost all character device drivers 986 * to set up the fasync queue, and for regular files by the file 987 * lease code. It returns negative on error, 0 if it did no changes 988 * and positive if it added/deleted the entry. 989 */ 990 int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp) 991 { 992 if (!on) 993 return fasync_remove_entry(filp, fapp); 994 return fasync_add_entry(fd, filp, fapp); 995 } 996 997 EXPORT_SYMBOL(fasync_helper); 998 999 /* 1000 * rcu_read_lock() is held 1001 */ 1002 static void kill_fasync_rcu(struct fasync_struct *fa, int sig, int band) 1003 { 1004 while (fa) { 1005 struct fown_struct *fown; 1006 1007 if (fa->magic != FASYNC_MAGIC) { 1008 printk(KERN_ERR "kill_fasync: bad magic number in " 1009 "fasync_struct!\n"); 1010 return; 1011 } 1012 read_lock(&fa->fa_lock); 1013 if (fa->fa_file) { 1014 fown = &fa->fa_file->f_owner; 1015 /* Don't send SIGURG to processes which have not set a 1016 queued signum: SIGURG has its own default signalling 1017 mechanism. */ 1018 if (!(sig == SIGURG && fown->signum == 0)) 1019 send_sigio(fown, fa->fa_fd, band); 1020 } 1021 read_unlock(&fa->fa_lock); 1022 fa = rcu_dereference(fa->fa_next); 1023 } 1024 } 1025 1026 void kill_fasync(struct fasync_struct **fp, int sig, int band) 1027 { 1028 /* First a quick test without locking: usually 1029 * the list is empty. 1030 */ 1031 if (*fp) { 1032 rcu_read_lock(); 1033 kill_fasync_rcu(rcu_dereference(*fp), sig, band); 1034 rcu_read_unlock(); 1035 } 1036 } 1037 EXPORT_SYMBOL(kill_fasync); 1038 1039 static int __init fcntl_init(void) 1040 { 1041 /* 1042 * Please add new bits here to ensure allocation uniqueness. 1043 * Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY 1044 * is defined as O_NONBLOCK on some platforms and not on others. 1045 */ 1046 BUILD_BUG_ON(21 - 1 /* for O_RDONLY being 0 */ != 1047 HWEIGHT32( 1048 (VALID_OPEN_FLAGS & ~(O_NONBLOCK | O_NDELAY)) | 1049 __FMODE_EXEC | __FMODE_NONOTIFY)); 1050 1051 fasync_cache = kmem_cache_create("fasync_cache", 1052 sizeof(struct fasync_struct), 0, SLAB_PANIC, NULL); 1053 return 0; 1054 } 1055 1056 module_init(fcntl_init) 1057