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 29 #include <linux/poll.h> 30 #include <asm/siginfo.h> 31 #include <linux/uaccess.h> 32 33 #define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT | O_NOATIME) 34 35 static int setfl(int fd, struct file * filp, unsigned long arg) 36 { 37 struct inode * inode = file_inode(filp); 38 int error = 0; 39 40 /* 41 * O_APPEND cannot be cleared if the file is marked as append-only 42 * and the file is open for write. 43 */ 44 if (((arg ^ filp->f_flags) & O_APPEND) && IS_APPEND(inode)) 45 return -EPERM; 46 47 /* O_NOATIME can only be set by the owner or superuser */ 48 if ((arg & O_NOATIME) && !(filp->f_flags & O_NOATIME)) 49 if (!inode_owner_or_capable(inode)) 50 return -EPERM; 51 52 /* required for strict SunOS emulation */ 53 if (O_NONBLOCK != O_NDELAY) 54 if (arg & O_NDELAY) 55 arg |= O_NONBLOCK; 56 57 /* Pipe packetized mode is controlled by O_DIRECT flag */ 58 if (!S_ISFIFO(inode->i_mode) && (arg & O_DIRECT)) { 59 if (!filp->f_mapping || !filp->f_mapping->a_ops || 60 !filp->f_mapping->a_ops->direct_IO) 61 return -EINVAL; 62 } 63 64 if (filp->f_op->check_flags) 65 error = filp->f_op->check_flags(arg); 66 if (error) 67 return error; 68 69 /* 70 * ->fasync() is responsible for setting the FASYNC bit. 71 */ 72 if (((arg ^ filp->f_flags) & FASYNC) && filp->f_op->fasync) { 73 error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0); 74 if (error < 0) 75 goto out; 76 if (error > 0) 77 error = 0; 78 } 79 spin_lock(&filp->f_lock); 80 filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK); 81 spin_unlock(&filp->f_lock); 82 83 out: 84 return error; 85 } 86 87 static void f_modown(struct file *filp, struct pid *pid, enum pid_type type, 88 int force) 89 { 90 write_lock_irq(&filp->f_owner.lock); 91 if (force || !filp->f_owner.pid) { 92 put_pid(filp->f_owner.pid); 93 filp->f_owner.pid = get_pid(pid); 94 filp->f_owner.pid_type = type; 95 96 if (pid) { 97 const struct cred *cred = current_cred(); 98 filp->f_owner.uid = cred->uid; 99 filp->f_owner.euid = cred->euid; 100 } 101 } 102 write_unlock_irq(&filp->f_owner.lock); 103 } 104 105 void __f_setown(struct file *filp, struct pid *pid, enum pid_type type, 106 int force) 107 { 108 security_file_set_fowner(filp); 109 f_modown(filp, pid, type, force); 110 } 111 EXPORT_SYMBOL(__f_setown); 112 113 int f_setown(struct file *filp, unsigned long arg, int force) 114 { 115 enum pid_type type; 116 struct pid *pid = NULL; 117 int who = arg, ret = 0; 118 119 type = PIDTYPE_TGID; 120 if (who < 0) { 121 /* avoid overflow below */ 122 if (who == INT_MIN) 123 return -EINVAL; 124 125 type = PIDTYPE_PGID; 126 who = -who; 127 } 128 129 rcu_read_lock(); 130 if (who) { 131 pid = find_vpid(who); 132 if (!pid) 133 ret = -ESRCH; 134 } 135 136 if (!ret) 137 __f_setown(filp, pid, type, force); 138 rcu_read_unlock(); 139 140 return ret; 141 } 142 EXPORT_SYMBOL(f_setown); 143 144 void f_delown(struct file *filp) 145 { 146 f_modown(filp, NULL, PIDTYPE_TGID, 1); 147 } 148 149 pid_t f_getown(struct file *filp) 150 { 151 pid_t pid; 152 read_lock(&filp->f_owner.lock); 153 pid = pid_vnr(filp->f_owner.pid); 154 if (filp->f_owner.pid_type == PIDTYPE_PGID) 155 pid = -pid; 156 read_unlock(&filp->f_owner.lock); 157 return pid; 158 } 159 160 static int f_setown_ex(struct file *filp, unsigned long arg) 161 { 162 struct f_owner_ex __user *owner_p = (void __user *)arg; 163 struct f_owner_ex owner; 164 struct pid *pid; 165 int type; 166 int ret; 167 168 ret = copy_from_user(&owner, owner_p, sizeof(owner)); 169 if (ret) 170 return -EFAULT; 171 172 switch (owner.type) { 173 case F_OWNER_TID: 174 type = PIDTYPE_PID; 175 break; 176 177 case F_OWNER_PID: 178 type = PIDTYPE_TGID; 179 break; 180 181 case F_OWNER_PGRP: 182 type = PIDTYPE_PGID; 183 break; 184 185 default: 186 return -EINVAL; 187 } 188 189 rcu_read_lock(); 190 pid = find_vpid(owner.pid); 191 if (owner.pid && !pid) 192 ret = -ESRCH; 193 else 194 __f_setown(filp, pid, type, 1); 195 rcu_read_unlock(); 196 197 return ret; 198 } 199 200 static int f_getown_ex(struct file *filp, unsigned long arg) 201 { 202 struct f_owner_ex __user *owner_p = (void __user *)arg; 203 struct f_owner_ex owner; 204 int ret = 0; 205 206 read_lock(&filp->f_owner.lock); 207 owner.pid = pid_vnr(filp->f_owner.pid); 208 switch (filp->f_owner.pid_type) { 209 case PIDTYPE_PID: 210 owner.type = F_OWNER_TID; 211 break; 212 213 case PIDTYPE_TGID: 214 owner.type = F_OWNER_PID; 215 break; 216 217 case PIDTYPE_PGID: 218 owner.type = F_OWNER_PGRP; 219 break; 220 221 default: 222 WARN_ON(1); 223 ret = -EINVAL; 224 break; 225 } 226 read_unlock(&filp->f_owner.lock); 227 228 if (!ret) { 229 ret = copy_to_user(owner_p, &owner, sizeof(owner)); 230 if (ret) 231 ret = -EFAULT; 232 } 233 return ret; 234 } 235 236 #ifdef CONFIG_CHECKPOINT_RESTORE 237 static int f_getowner_uids(struct file *filp, unsigned long arg) 238 { 239 struct user_namespace *user_ns = current_user_ns(); 240 uid_t __user *dst = (void __user *)arg; 241 uid_t src[2]; 242 int err; 243 244 read_lock(&filp->f_owner.lock); 245 src[0] = from_kuid(user_ns, filp->f_owner.uid); 246 src[1] = from_kuid(user_ns, filp->f_owner.euid); 247 read_unlock(&filp->f_owner.lock); 248 249 err = put_user(src[0], &dst[0]); 250 err |= put_user(src[1], &dst[1]); 251 252 return err; 253 } 254 #else 255 static int f_getowner_uids(struct file *filp, unsigned long arg) 256 { 257 return -EINVAL; 258 } 259 #endif 260 261 static bool rw_hint_valid(enum rw_hint hint) 262 { 263 switch (hint) { 264 case RWF_WRITE_LIFE_NOT_SET: 265 case RWH_WRITE_LIFE_NONE: 266 case RWH_WRITE_LIFE_SHORT: 267 case RWH_WRITE_LIFE_MEDIUM: 268 case RWH_WRITE_LIFE_LONG: 269 case RWH_WRITE_LIFE_EXTREME: 270 return true; 271 default: 272 return false; 273 } 274 } 275 276 static long fcntl_rw_hint(struct file *file, unsigned int cmd, 277 unsigned long arg) 278 { 279 struct inode *inode = file_inode(file); 280 u64 *argp = (u64 __user *)arg; 281 enum rw_hint hint; 282 u64 h; 283 284 switch (cmd) { 285 case F_GET_FILE_RW_HINT: 286 h = file_write_hint(file); 287 if (copy_to_user(argp, &h, sizeof(*argp))) 288 return -EFAULT; 289 return 0; 290 case F_SET_FILE_RW_HINT: 291 if (copy_from_user(&h, argp, sizeof(h))) 292 return -EFAULT; 293 hint = (enum rw_hint) h; 294 if (!rw_hint_valid(hint)) 295 return -EINVAL; 296 297 spin_lock(&file->f_lock); 298 file->f_write_hint = hint; 299 spin_unlock(&file->f_lock); 300 return 0; 301 case F_GET_RW_HINT: 302 h = inode->i_write_hint; 303 if (copy_to_user(argp, &h, sizeof(*argp))) 304 return -EFAULT; 305 return 0; 306 case F_SET_RW_HINT: 307 if (copy_from_user(&h, argp, sizeof(h))) 308 return -EFAULT; 309 hint = (enum rw_hint) h; 310 if (!rw_hint_valid(hint)) 311 return -EINVAL; 312 313 inode_lock(inode); 314 inode->i_write_hint = hint; 315 inode_unlock(inode); 316 return 0; 317 default: 318 return -EINVAL; 319 } 320 } 321 322 static long do_fcntl(int fd, unsigned int cmd, unsigned long arg, 323 struct file *filp) 324 { 325 void __user *argp = (void __user *)arg; 326 struct flock flock; 327 long err = -EINVAL; 328 329 switch (cmd) { 330 case F_DUPFD: 331 err = f_dupfd(arg, filp, 0); 332 break; 333 case F_DUPFD_CLOEXEC: 334 err = f_dupfd(arg, filp, O_CLOEXEC); 335 break; 336 case F_GETFD: 337 err = get_close_on_exec(fd) ? FD_CLOEXEC : 0; 338 break; 339 case F_SETFD: 340 err = 0; 341 set_close_on_exec(fd, arg & FD_CLOEXEC); 342 break; 343 case F_GETFL: 344 err = filp->f_flags; 345 break; 346 case F_SETFL: 347 err = setfl(fd, filp, arg); 348 break; 349 #if BITS_PER_LONG != 32 350 /* 32-bit arches must use fcntl64() */ 351 case F_OFD_GETLK: 352 #endif 353 case F_GETLK: 354 if (copy_from_user(&flock, argp, sizeof(flock))) 355 return -EFAULT; 356 err = fcntl_getlk(filp, cmd, &flock); 357 if (!err && copy_to_user(argp, &flock, sizeof(flock))) 358 return -EFAULT; 359 break; 360 #if BITS_PER_LONG != 32 361 /* 32-bit arches must use fcntl64() */ 362 case F_OFD_SETLK: 363 case F_OFD_SETLKW: 364 #endif 365 /* Fallthrough */ 366 case F_SETLK: 367 case F_SETLKW: 368 if (copy_from_user(&flock, argp, sizeof(flock))) 369 return -EFAULT; 370 err = fcntl_setlk(fd, filp, cmd, &flock); 371 break; 372 case F_GETOWN: 373 /* 374 * XXX If f_owner is a process group, the 375 * negative return value will get converted 376 * into an error. Oops. If we keep the 377 * current syscall conventions, the only way 378 * to fix this will be in libc. 379 */ 380 err = f_getown(filp); 381 force_successful_syscall_return(); 382 break; 383 case F_SETOWN: 384 err = f_setown(filp, arg, 1); 385 break; 386 case F_GETOWN_EX: 387 err = f_getown_ex(filp, arg); 388 break; 389 case F_SETOWN_EX: 390 err = f_setown_ex(filp, arg); 391 break; 392 case F_GETOWNER_UIDS: 393 err = f_getowner_uids(filp, arg); 394 break; 395 case F_GETSIG: 396 err = filp->f_owner.signum; 397 break; 398 case F_SETSIG: 399 /* arg == 0 restores default behaviour. */ 400 if (!valid_signal(arg)) { 401 break; 402 } 403 err = 0; 404 filp->f_owner.signum = arg; 405 break; 406 case F_GETLEASE: 407 err = fcntl_getlease(filp); 408 break; 409 case F_SETLEASE: 410 err = fcntl_setlease(fd, filp, arg); 411 break; 412 case F_NOTIFY: 413 err = fcntl_dirnotify(fd, filp, arg); 414 break; 415 case F_SETPIPE_SZ: 416 case F_GETPIPE_SZ: 417 err = pipe_fcntl(filp, cmd, arg); 418 break; 419 case F_ADD_SEALS: 420 case F_GET_SEALS: 421 err = memfd_fcntl(filp, cmd, arg); 422 break; 423 case F_GET_RW_HINT: 424 case F_SET_RW_HINT: 425 case F_GET_FILE_RW_HINT: 426 case F_SET_FILE_RW_HINT: 427 err = fcntl_rw_hint(filp, cmd, arg); 428 break; 429 default: 430 break; 431 } 432 return err; 433 } 434 435 static int check_fcntl_cmd(unsigned cmd) 436 { 437 switch (cmd) { 438 case F_DUPFD: 439 case F_DUPFD_CLOEXEC: 440 case F_GETFD: 441 case F_SETFD: 442 case F_GETFL: 443 return 1; 444 } 445 return 0; 446 } 447 448 SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg) 449 { 450 struct fd f = fdget_raw(fd); 451 long err = -EBADF; 452 453 if (!f.file) 454 goto out; 455 456 if (unlikely(f.file->f_mode & FMODE_PATH)) { 457 if (!check_fcntl_cmd(cmd)) 458 goto out1; 459 } 460 461 err = security_file_fcntl(f.file, cmd, arg); 462 if (!err) 463 err = do_fcntl(fd, cmd, arg, f.file); 464 465 out1: 466 fdput(f); 467 out: 468 return err; 469 } 470 471 #if BITS_PER_LONG == 32 472 SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd, 473 unsigned long, arg) 474 { 475 void __user *argp = (void __user *)arg; 476 struct fd f = fdget_raw(fd); 477 struct flock64 flock; 478 long err = -EBADF; 479 480 if (!f.file) 481 goto out; 482 483 if (unlikely(f.file->f_mode & FMODE_PATH)) { 484 if (!check_fcntl_cmd(cmd)) 485 goto out1; 486 } 487 488 err = security_file_fcntl(f.file, cmd, arg); 489 if (err) 490 goto out1; 491 492 switch (cmd) { 493 case F_GETLK64: 494 case F_OFD_GETLK: 495 err = -EFAULT; 496 if (copy_from_user(&flock, argp, sizeof(flock))) 497 break; 498 err = fcntl_getlk64(f.file, cmd, &flock); 499 if (!err && copy_to_user(argp, &flock, sizeof(flock))) 500 err = -EFAULT; 501 break; 502 case F_SETLK64: 503 case F_SETLKW64: 504 case F_OFD_SETLK: 505 case F_OFD_SETLKW: 506 err = -EFAULT; 507 if (copy_from_user(&flock, argp, sizeof(flock))) 508 break; 509 err = fcntl_setlk64(fd, f.file, cmd, &flock); 510 break; 511 default: 512 err = do_fcntl(fd, cmd, arg, f.file); 513 break; 514 } 515 out1: 516 fdput(f); 517 out: 518 return err; 519 } 520 #endif 521 522 #ifdef CONFIG_COMPAT 523 /* careful - don't use anywhere else */ 524 #define copy_flock_fields(dst, src) \ 525 (dst)->l_type = (src)->l_type; \ 526 (dst)->l_whence = (src)->l_whence; \ 527 (dst)->l_start = (src)->l_start; \ 528 (dst)->l_len = (src)->l_len; \ 529 (dst)->l_pid = (src)->l_pid; 530 531 static int get_compat_flock(struct flock *kfl, const struct compat_flock __user *ufl) 532 { 533 struct compat_flock fl; 534 535 if (copy_from_user(&fl, ufl, sizeof(struct compat_flock))) 536 return -EFAULT; 537 copy_flock_fields(kfl, &fl); 538 return 0; 539 } 540 541 static int get_compat_flock64(struct flock *kfl, const struct compat_flock64 __user *ufl) 542 { 543 struct compat_flock64 fl; 544 545 if (copy_from_user(&fl, ufl, sizeof(struct compat_flock64))) 546 return -EFAULT; 547 copy_flock_fields(kfl, &fl); 548 return 0; 549 } 550 551 static int put_compat_flock(const struct flock *kfl, struct compat_flock __user *ufl) 552 { 553 struct compat_flock fl; 554 555 memset(&fl, 0, sizeof(struct compat_flock)); 556 copy_flock_fields(&fl, kfl); 557 if (copy_to_user(ufl, &fl, sizeof(struct compat_flock))) 558 return -EFAULT; 559 return 0; 560 } 561 562 static int put_compat_flock64(const struct flock *kfl, struct compat_flock64 __user *ufl) 563 { 564 struct compat_flock64 fl; 565 566 BUILD_BUG_ON(sizeof(kfl->l_start) > sizeof(ufl->l_start)); 567 BUILD_BUG_ON(sizeof(kfl->l_len) > sizeof(ufl->l_len)); 568 569 memset(&fl, 0, sizeof(struct compat_flock64)); 570 copy_flock_fields(&fl, kfl); 571 if (copy_to_user(ufl, &fl, sizeof(struct compat_flock64))) 572 return -EFAULT; 573 return 0; 574 } 575 #undef copy_flock_fields 576 577 static unsigned int 578 convert_fcntl_cmd(unsigned int cmd) 579 { 580 switch (cmd) { 581 case F_GETLK64: 582 return F_GETLK; 583 case F_SETLK64: 584 return F_SETLK; 585 case F_SETLKW64: 586 return F_SETLKW; 587 } 588 589 return cmd; 590 } 591 592 /* 593 * GETLK was successful and we need to return the data, but it needs to fit in 594 * the compat structure. 595 * l_start shouldn't be too big, unless the original start + end is greater than 596 * COMPAT_OFF_T_MAX, in which case the app was asking for trouble, so we return 597 * -EOVERFLOW in that case. l_len could be too big, in which case we just 598 * truncate it, and only allow the app to see that part of the conflicting lock 599 * that might make sense to it anyway 600 */ 601 static int fixup_compat_flock(struct flock *flock) 602 { 603 if (flock->l_start > COMPAT_OFF_T_MAX) 604 return -EOVERFLOW; 605 if (flock->l_len > COMPAT_OFF_T_MAX) 606 flock->l_len = COMPAT_OFF_T_MAX; 607 return 0; 608 } 609 610 static long do_compat_fcntl64(unsigned int fd, unsigned int cmd, 611 compat_ulong_t arg) 612 { 613 struct fd f = fdget_raw(fd); 614 struct flock flock; 615 long err = -EBADF; 616 617 if (!f.file) 618 return err; 619 620 if (unlikely(f.file->f_mode & FMODE_PATH)) { 621 if (!check_fcntl_cmd(cmd)) 622 goto out_put; 623 } 624 625 err = security_file_fcntl(f.file, cmd, arg); 626 if (err) 627 goto out_put; 628 629 switch (cmd) { 630 case F_GETLK: 631 err = get_compat_flock(&flock, compat_ptr(arg)); 632 if (err) 633 break; 634 err = fcntl_getlk(f.file, convert_fcntl_cmd(cmd), &flock); 635 if (err) 636 break; 637 err = fixup_compat_flock(&flock); 638 if (!err) 639 err = put_compat_flock(&flock, compat_ptr(arg)); 640 break; 641 case F_GETLK64: 642 case F_OFD_GETLK: 643 err = get_compat_flock64(&flock, compat_ptr(arg)); 644 if (err) 645 break; 646 err = fcntl_getlk(f.file, convert_fcntl_cmd(cmd), &flock); 647 if (!err) 648 err = put_compat_flock64(&flock, compat_ptr(arg)); 649 break; 650 case F_SETLK: 651 case F_SETLKW: 652 err = get_compat_flock(&flock, compat_ptr(arg)); 653 if (err) 654 break; 655 err = fcntl_setlk(fd, f.file, convert_fcntl_cmd(cmd), &flock); 656 break; 657 case F_SETLK64: 658 case F_SETLKW64: 659 case F_OFD_SETLK: 660 case F_OFD_SETLKW: 661 err = get_compat_flock64(&flock, compat_ptr(arg)); 662 if (err) 663 break; 664 err = fcntl_setlk(fd, f.file, convert_fcntl_cmd(cmd), &flock); 665 break; 666 default: 667 err = do_fcntl(fd, cmd, arg, f.file); 668 break; 669 } 670 out_put: 671 fdput(f); 672 return err; 673 } 674 675 COMPAT_SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd, 676 compat_ulong_t, arg) 677 { 678 return do_compat_fcntl64(fd, cmd, arg); 679 } 680 681 COMPAT_SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, 682 compat_ulong_t, arg) 683 { 684 switch (cmd) { 685 case F_GETLK64: 686 case F_SETLK64: 687 case F_SETLKW64: 688 case F_OFD_GETLK: 689 case F_OFD_SETLK: 690 case F_OFD_SETLKW: 691 return -EINVAL; 692 } 693 return do_compat_fcntl64(fd, cmd, arg); 694 } 695 #endif 696 697 /* Table to convert sigio signal codes into poll band bitmaps */ 698 699 static const __poll_t band_table[NSIGPOLL] = { 700 EPOLLIN | EPOLLRDNORM, /* POLL_IN */ 701 EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND, /* POLL_OUT */ 702 EPOLLIN | EPOLLRDNORM | EPOLLMSG, /* POLL_MSG */ 703 EPOLLERR, /* POLL_ERR */ 704 EPOLLPRI | EPOLLRDBAND, /* POLL_PRI */ 705 EPOLLHUP | EPOLLERR /* POLL_HUP */ 706 }; 707 708 static inline int sigio_perm(struct task_struct *p, 709 struct fown_struct *fown, int sig) 710 { 711 const struct cred *cred; 712 int ret; 713 714 rcu_read_lock(); 715 cred = __task_cred(p); 716 ret = ((uid_eq(fown->euid, GLOBAL_ROOT_UID) || 717 uid_eq(fown->euid, cred->suid) || uid_eq(fown->euid, cred->uid) || 718 uid_eq(fown->uid, cred->suid) || uid_eq(fown->uid, cred->uid)) && 719 !security_file_send_sigiotask(p, fown, sig)); 720 rcu_read_unlock(); 721 return ret; 722 } 723 724 static void send_sigio_to_task(struct task_struct *p, 725 struct fown_struct *fown, 726 int fd, int reason, enum pid_type type) 727 { 728 /* 729 * F_SETSIG can change ->signum lockless in parallel, make 730 * sure we read it once and use the same value throughout. 731 */ 732 int signum = READ_ONCE(fown->signum); 733 734 if (!sigio_perm(p, fown, signum)) 735 return; 736 737 switch (signum) { 738 kernel_siginfo_t si; 739 default: 740 /* Queue a rt signal with the appropriate fd as its 741 value. We use SI_SIGIO as the source, not 742 SI_KERNEL, since kernel signals always get 743 delivered even if we can't queue. Failure to 744 queue in this case _should_ be reported; we fall 745 back to SIGIO in that case. --sct */ 746 clear_siginfo(&si); 747 si.si_signo = signum; 748 si.si_errno = 0; 749 si.si_code = reason; 750 /* 751 * Posix definies POLL_IN and friends to be signal 752 * specific si_codes for SIG_POLL. Linux extended 753 * these si_codes to other signals in a way that is 754 * ambiguous if other signals also have signal 755 * specific si_codes. In that case use SI_SIGIO instead 756 * to remove the ambiguity. 757 */ 758 if ((signum != SIGPOLL) && sig_specific_sicodes(signum)) 759 si.si_code = SI_SIGIO; 760 761 /* Make sure we are called with one of the POLL_* 762 reasons, otherwise we could leak kernel stack into 763 userspace. */ 764 BUG_ON((reason < POLL_IN) || ((reason - POLL_IN) >= NSIGPOLL)); 765 if (reason - POLL_IN >= NSIGPOLL) 766 si.si_band = ~0L; 767 else 768 si.si_band = mangle_poll(band_table[reason - POLL_IN]); 769 si.si_fd = fd; 770 if (!do_send_sig_info(signum, &si, p, type)) 771 break; 772 /* fall-through: fall back on the old plain SIGIO signal */ 773 case 0: 774 do_send_sig_info(SIGIO, SEND_SIG_PRIV, p, type); 775 } 776 } 777 778 void send_sigio(struct fown_struct *fown, int fd, int band) 779 { 780 struct task_struct *p; 781 enum pid_type type; 782 struct pid *pid; 783 784 read_lock(&fown->lock); 785 786 type = fown->pid_type; 787 pid = fown->pid; 788 if (!pid) 789 goto out_unlock_fown; 790 791 if (type <= PIDTYPE_TGID) { 792 rcu_read_lock(); 793 p = pid_task(pid, PIDTYPE_PID); 794 if (p) 795 send_sigio_to_task(p, fown, fd, band, type); 796 rcu_read_unlock(); 797 } else { 798 read_lock(&tasklist_lock); 799 do_each_pid_task(pid, type, p) { 800 send_sigio_to_task(p, fown, fd, band, type); 801 } while_each_pid_task(pid, type, p); 802 read_unlock(&tasklist_lock); 803 } 804 out_unlock_fown: 805 read_unlock(&fown->lock); 806 } 807 808 static void send_sigurg_to_task(struct task_struct *p, 809 struct fown_struct *fown, enum pid_type type) 810 { 811 if (sigio_perm(p, fown, SIGURG)) 812 do_send_sig_info(SIGURG, SEND_SIG_PRIV, p, type); 813 } 814 815 int send_sigurg(struct fown_struct *fown) 816 { 817 struct task_struct *p; 818 enum pid_type type; 819 struct pid *pid; 820 int ret = 0; 821 822 read_lock(&fown->lock); 823 824 type = fown->pid_type; 825 pid = fown->pid; 826 if (!pid) 827 goto out_unlock_fown; 828 829 ret = 1; 830 831 if (type <= PIDTYPE_TGID) { 832 rcu_read_lock(); 833 p = pid_task(pid, PIDTYPE_PID); 834 if (p) 835 send_sigurg_to_task(p, fown, type); 836 rcu_read_unlock(); 837 } else { 838 read_lock(&tasklist_lock); 839 do_each_pid_task(pid, type, p) { 840 send_sigurg_to_task(p, fown, type); 841 } while_each_pid_task(pid, type, p); 842 read_unlock(&tasklist_lock); 843 } 844 out_unlock_fown: 845 read_unlock(&fown->lock); 846 return ret; 847 } 848 849 static DEFINE_SPINLOCK(fasync_lock); 850 static struct kmem_cache *fasync_cache __read_mostly; 851 852 static void fasync_free_rcu(struct rcu_head *head) 853 { 854 kmem_cache_free(fasync_cache, 855 container_of(head, struct fasync_struct, fa_rcu)); 856 } 857 858 /* 859 * Remove a fasync entry. If successfully removed, return 860 * positive and clear the FASYNC flag. If no entry exists, 861 * do nothing and return 0. 862 * 863 * NOTE! It is very important that the FASYNC flag always 864 * match the state "is the filp on a fasync list". 865 * 866 */ 867 int fasync_remove_entry(struct file *filp, struct fasync_struct **fapp) 868 { 869 struct fasync_struct *fa, **fp; 870 int result = 0; 871 872 spin_lock(&filp->f_lock); 873 spin_lock(&fasync_lock); 874 for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) { 875 if (fa->fa_file != filp) 876 continue; 877 878 write_lock_irq(&fa->fa_lock); 879 fa->fa_file = NULL; 880 write_unlock_irq(&fa->fa_lock); 881 882 *fp = fa->fa_next; 883 call_rcu(&fa->fa_rcu, fasync_free_rcu); 884 filp->f_flags &= ~FASYNC; 885 result = 1; 886 break; 887 } 888 spin_unlock(&fasync_lock); 889 spin_unlock(&filp->f_lock); 890 return result; 891 } 892 893 struct fasync_struct *fasync_alloc(void) 894 { 895 return kmem_cache_alloc(fasync_cache, GFP_KERNEL); 896 } 897 898 /* 899 * NOTE! This can be used only for unused fasync entries: 900 * entries that actually got inserted on the fasync list 901 * need to be released by rcu - see fasync_remove_entry. 902 */ 903 void fasync_free(struct fasync_struct *new) 904 { 905 kmem_cache_free(fasync_cache, new); 906 } 907 908 /* 909 * Insert a new entry into the fasync list. Return the pointer to the 910 * old one if we didn't use the new one. 911 * 912 * NOTE! It is very important that the FASYNC flag always 913 * match the state "is the filp on a fasync list". 914 */ 915 struct fasync_struct *fasync_insert_entry(int fd, struct file *filp, struct fasync_struct **fapp, struct fasync_struct *new) 916 { 917 struct fasync_struct *fa, **fp; 918 919 spin_lock(&filp->f_lock); 920 spin_lock(&fasync_lock); 921 for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) { 922 if (fa->fa_file != filp) 923 continue; 924 925 write_lock_irq(&fa->fa_lock); 926 fa->fa_fd = fd; 927 write_unlock_irq(&fa->fa_lock); 928 goto out; 929 } 930 931 rwlock_init(&new->fa_lock); 932 new->magic = FASYNC_MAGIC; 933 new->fa_file = filp; 934 new->fa_fd = fd; 935 new->fa_next = *fapp; 936 rcu_assign_pointer(*fapp, new); 937 filp->f_flags |= FASYNC; 938 939 out: 940 spin_unlock(&fasync_lock); 941 spin_unlock(&filp->f_lock); 942 return fa; 943 } 944 945 /* 946 * Add a fasync entry. Return negative on error, positive if 947 * added, and zero if did nothing but change an existing one. 948 */ 949 static int fasync_add_entry(int fd, struct file *filp, struct fasync_struct **fapp) 950 { 951 struct fasync_struct *new; 952 953 new = fasync_alloc(); 954 if (!new) 955 return -ENOMEM; 956 957 /* 958 * fasync_insert_entry() returns the old (update) entry if 959 * it existed. 960 * 961 * So free the (unused) new entry and return 0 to let the 962 * caller know that we didn't add any new fasync entries. 963 */ 964 if (fasync_insert_entry(fd, filp, fapp, new)) { 965 fasync_free(new); 966 return 0; 967 } 968 969 return 1; 970 } 971 972 /* 973 * fasync_helper() is used by almost all character device drivers 974 * to set up the fasync queue, and for regular files by the file 975 * lease code. It returns negative on error, 0 if it did no changes 976 * and positive if it added/deleted the entry. 977 */ 978 int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp) 979 { 980 if (!on) 981 return fasync_remove_entry(filp, fapp); 982 return fasync_add_entry(fd, filp, fapp); 983 } 984 985 EXPORT_SYMBOL(fasync_helper); 986 987 /* 988 * rcu_read_lock() is held 989 */ 990 static void kill_fasync_rcu(struct fasync_struct *fa, int sig, int band) 991 { 992 while (fa) { 993 struct fown_struct *fown; 994 995 if (fa->magic != FASYNC_MAGIC) { 996 printk(KERN_ERR "kill_fasync: bad magic number in " 997 "fasync_struct!\n"); 998 return; 999 } 1000 read_lock(&fa->fa_lock); 1001 if (fa->fa_file) { 1002 fown = &fa->fa_file->f_owner; 1003 /* Don't send SIGURG to processes which have not set a 1004 queued signum: SIGURG has its own default signalling 1005 mechanism. */ 1006 if (!(sig == SIGURG && fown->signum == 0)) 1007 send_sigio(fown, fa->fa_fd, band); 1008 } 1009 read_unlock(&fa->fa_lock); 1010 fa = rcu_dereference(fa->fa_next); 1011 } 1012 } 1013 1014 void kill_fasync(struct fasync_struct **fp, int sig, int band) 1015 { 1016 /* First a quick test without locking: usually 1017 * the list is empty. 1018 */ 1019 if (*fp) { 1020 rcu_read_lock(); 1021 kill_fasync_rcu(rcu_dereference(*fp), sig, band); 1022 rcu_read_unlock(); 1023 } 1024 } 1025 EXPORT_SYMBOL(kill_fasync); 1026 1027 static int __init fcntl_init(void) 1028 { 1029 /* 1030 * Please add new bits here to ensure allocation uniqueness. 1031 * Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY 1032 * is defined as O_NONBLOCK on some platforms and not on others. 1033 */ 1034 BUILD_BUG_ON(21 - 1 /* for O_RDONLY being 0 */ != 1035 HWEIGHT32( 1036 (VALID_OPEN_FLAGS & ~(O_NONBLOCK | O_NDELAY)) | 1037 __FMODE_EXEC | __FMODE_NONOTIFY)); 1038 1039 fasync_cache = kmem_cache_create("fasync_cache", 1040 sizeof(struct fasync_struct), 0, SLAB_PANIC, NULL); 1041 return 0; 1042 } 1043 1044 module_init(fcntl_init) 1045