fs/fcntl.c

   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/shmem_fs.h>
  27 #include <linux/compat.h>
  28
  29 #include <asm/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_PID;
 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_PID, 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_MAX;
 175                 break;
 176
 177         case F_OWNER_PID:
 178                 type = PIDTYPE_PID;
 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_MAX:
 210                 owner.type = F_OWNER_TID;
 211                 break;
 212
 213         case PIDTYPE_PID:
 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 = shmem_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 COMPAT_SYSCALL_DEFINE3(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(fcntl, unsigned int, fd, unsigned int, cmd,
 676                        compat_ulong_t, arg)
 677 {
 678         switch (cmd) {
 679         case F_GETLK64:
 680         case F_SETLK64:
 681         case F_SETLKW64:
 682         case F_OFD_GETLK:
 683         case F_OFD_SETLK:
 684         case F_OFD_SETLKW:
 685                 return -EINVAL;
 686         }
 687         return compat_sys_fcntl64(fd, cmd, arg);
 688 }
 689 #endif
 690
 691 /* Table to convert sigio signal codes into poll band bitmaps */
 692
 693 static const long band_table[NSIGPOLL] = {
 694         POLLIN | POLLRDNORM,                    /* POLL_IN */
 695         POLLOUT | POLLWRNORM | POLLWRBAND,      /* POLL_OUT */
 696         POLLIN | POLLRDNORM | POLLMSG,          /* POLL_MSG */
 697         POLLERR,                                /* POLL_ERR */
 698         POLLPRI | POLLRDBAND,                   /* POLL_PRI */
 699         POLLHUP | POLLERR                       /* POLL_HUP */
 700 };
 701
 702 static inline int sigio_perm(struct task_struct *p,
 703                              struct fown_struct *fown, int sig)
 704 {
 705         const struct cred *cred;
 706         int ret;
 707
 708         rcu_read_lock();
 709         cred = __task_cred(p);
 710         ret = ((uid_eq(fown->euid, GLOBAL_ROOT_UID) ||
 711                 uid_eq(fown->euid, cred->suid) || uid_eq(fown->euid, cred->uid) ||
 712                 uid_eq(fown->uid,  cred->suid) || uid_eq(fown->uid,  cred->uid)) &&
 713                !security_file_send_sigiotask(p, fown, sig));
 714         rcu_read_unlock();
 715         return ret;
 716 }
 717
 718 static void send_sigio_to_task(struct task_struct *p,
 719                                struct fown_struct *fown,
 720                                int fd, int reason, int group)
 721 {
 722         /*
 723          * F_SETSIG can change ->signum lockless in parallel, make
 724          * sure we read it once and use the same value throughout.
 725          */
 726         int signum = ACCESS_ONCE(fown->signum);
 727
 728         if (!sigio_perm(p, fown, signum))
 729                 return;
 730
 731         switch (signum) {
 732                 siginfo_t si;
 733                 default:
 734                         /* Queue a rt signal with the appropriate fd as its
 735                            value.  We use SI_SIGIO as the source, not
 736                            SI_KERNEL, since kernel signals always get
 737                            delivered even if we can't queue.  Failure to
 738                            queue in this case _should_ be reported; we fall
 739                            back to SIGIO in that case. --sct */
 740                         si.si_signo = signum;
 741                         si.si_errno = 0;
 742                         si.si_code  = reason;
 743                         /*
 744                          * Posix definies POLL_IN and friends to be signal
 745                          * specific si_codes for SIG_POLL.  Linux extended
 746                          * these si_codes to other signals in a way that is
 747                          * ambiguous if other signals also have signal
 748                          * specific si_codes.  In that case use SI_SIGIO instead
 749                          * to remove the ambiguity.
 750                          */
 751                         if ((signum != SIGPOLL) && sig_specific_sicodes(signum))
 752                                 si.si_code = SI_SIGIO;
 753
 754                         /* Make sure we are called with one of the POLL_*
 755                            reasons, otherwise we could leak kernel stack into
 756                            userspace.  */
 757                         BUG_ON((reason < POLL_IN) || ((reason - POLL_IN) >= NSIGPOLL));
 758                         if (reason - POLL_IN >= NSIGPOLL)
 759                                 si.si_band  = ~0L;
 760                         else
 761                                 si.si_band = band_table[reason - POLL_IN];
 762                         si.si_fd    = fd;
 763                         if (!do_send_sig_info(signum, &si, p, group))
 764                                 break;
 765                 /* fall-through: fall back on the old plain SIGIO signal */
 766                 case 0:
 767                         do_send_sig_info(SIGIO, SEND_SIG_PRIV, p, group);
 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         struct pid *pid;
 776         int group = 1;
 777
 778         read_lock(&fown->lock);
 779
 780         type = fown->pid_type;
 781         if (type == PIDTYPE_MAX) {
 782                 group = 0;
 783                 type = PIDTYPE_PID;
 784         }
 785
 786         pid = fown->pid;
 787         if (!pid)
 788                 goto out_unlock_fown;
 789
 790         read_lock(&tasklist_lock);
 791         do_each_pid_task(pid, type, p) {
 792                 send_sigio_to_task(p, fown, fd, band, group);
 793         } while_each_pid_task(pid, type, p);
 794         read_unlock(&tasklist_lock);
 795  out_unlock_fown:
 796         read_unlock(&fown->lock);
 797 }
 798
 799 static void send_sigurg_to_task(struct task_struct *p,
 800                                 struct fown_struct *fown, int group)
 801 {
 802         if (sigio_perm(p, fown, SIGURG))
 803                 do_send_sig_info(SIGURG, SEND_SIG_PRIV, p, group);
 804 }
 805
 806 int send_sigurg(struct fown_struct *fown)
 807 {
 808         struct task_struct *p;
 809         enum pid_type type;
 810         struct pid *pid;
 811         int group = 1;
 812         int ret = 0;
 813
 814         read_lock(&fown->lock);
 815
 816         type = fown->pid_type;
 817         if (type == PIDTYPE_MAX) {
 818                 group = 0;
 819                 type = PIDTYPE_PID;
 820         }
 821
 822         pid = fown->pid;
 823         if (!pid)
 824                 goto out_unlock_fown;
 825
 826         ret = 1;
 827
 828         read_lock(&tasklist_lock);
 829         do_each_pid_task(pid, type, p) {
 830                 send_sigurg_to_task(p, fown, group);
 831         } while_each_pid_task(pid, type, p);
 832         read_unlock(&tasklist_lock);
 833  out_unlock_fown:
 834         read_unlock(&fown->lock);
 835         return ret;
 836 }
 837
 838 static DEFINE_SPINLOCK(fasync_lock);
 839 static struct kmem_cache *fasync_cache __read_mostly;
 840
 841 static void fasync_free_rcu(struct rcu_head *head)
 842 {
 843         kmem_cache_free(fasync_cache,
 844                         container_of(head, struct fasync_struct, fa_rcu));
 845 }
 846
 847 /*
 848  * Remove a fasync entry. If successfully removed, return
 849  * positive and clear the FASYNC flag. If no entry exists,
 850  * do nothing and return 0.
 851  *
 852  * NOTE! It is very important that the FASYNC flag always
 853  * match the state "is the filp on a fasync list".
 854  *
 855  */
 856 int fasync_remove_entry(struct file *filp, struct fasync_struct **fapp)
 857 {
 858         struct fasync_struct *fa, **fp;
 859         int result = 0;
 860
 861         spin_lock(&filp->f_lock);
 862         spin_lock(&fasync_lock);
 863         for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
 864                 if (fa->fa_file != filp)
 865                         continue;
 866
 867                 spin_lock_irq(&fa->fa_lock);
 868                 fa->fa_file = NULL;
 869                 spin_unlock_irq(&fa->fa_lock);
 870
 871                 *fp = fa->fa_next;
 872                 call_rcu(&fa->fa_rcu, fasync_free_rcu);
 873                 filp->f_flags &= ~FASYNC;
 874                 result = 1;
 875                 break;
 876         }
 877         spin_unlock(&fasync_lock);
 878         spin_unlock(&filp->f_lock);
 879         return result;
 880 }
 881
 882 struct fasync_struct *fasync_alloc(void)
 883 {
 884         return kmem_cache_alloc(fasync_cache, GFP_KERNEL);
 885 }
 886
 887 /*
 888  * NOTE! This can be used only for unused fasync entries:
 889  * entries that actually got inserted on the fasync list
 890  * need to be released by rcu - see fasync_remove_entry.
 891  */
 892 void fasync_free(struct fasync_struct *new)
 893 {
 894         kmem_cache_free(fasync_cache, new);
 895 }
 896
 897 /*
 898  * Insert a new entry into the fasync list.  Return the pointer to the
 899  * old one if we didn't use the new one.
 900  *
 901  * NOTE! It is very important that the FASYNC flag always
 902  * match the state "is the filp on a fasync list".
 903  */
 904 struct fasync_struct *fasync_insert_entry(int fd, struct file *filp, struct fasync_struct **fapp, struct fasync_struct *new)
 905 {
 906         struct fasync_struct *fa, **fp;
 907
 908         spin_lock(&filp->f_lock);
 909         spin_lock(&fasync_lock);
 910         for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
 911                 if (fa->fa_file != filp)
 912                         continue;
 913
 914                 spin_lock_irq(&fa->fa_lock);
 915                 fa->fa_fd = fd;
 916                 spin_unlock_irq(&fa->fa_lock);
 917                 goto out;
 918         }
 919
 920         spin_lock_init(&new->fa_lock);
 921         new->magic = FASYNC_MAGIC;
 922         new->fa_file = filp;
 923         new->fa_fd = fd;
 924         new->fa_next = *fapp;
 925         rcu_assign_pointer(*fapp, new);
 926         filp->f_flags |= FASYNC;
 927
 928 out:
 929         spin_unlock(&fasync_lock);
 930         spin_unlock(&filp->f_lock);
 931         return fa;
 932 }
 933
 934 /*
 935  * Add a fasync entry. Return negative on error, positive if
 936  * added, and zero if did nothing but change an existing one.
 937  */
 938 static int fasync_add_entry(int fd, struct file *filp, struct fasync_struct **fapp)
 939 {
 940         struct fasync_struct *new;
 941
 942         new = fasync_alloc();
 943         if (!new)
 944                 return -ENOMEM;
 945
 946         /*
 947          * fasync_insert_entry() returns the old (update) entry if
 948          * it existed.
 949          *
 950          * So free the (unused) new entry and return 0 to let the
 951          * caller know that we didn't add any new fasync entries.
 952          */
 953         if (fasync_insert_entry(fd, filp, fapp, new)) {
 954                 fasync_free(new);
 955                 return 0;
 956         }
 957
 958         return 1;
 959 }
 960
 961 /*
 962  * fasync_helper() is used by almost all character device drivers
 963  * to set up the fasync queue, and for regular files by the file
 964  * lease code. It returns negative on error, 0 if it did no changes
 965  * and positive if it added/deleted the entry.
 966  */
 967 int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp)
 968 {
 969         if (!on)
 970                 return fasync_remove_entry(filp, fapp);
 971         return fasync_add_entry(fd, filp, fapp);
 972 }
 973
 974 EXPORT_SYMBOL(fasync_helper);
 975
 976 /*
 977  * rcu_read_lock() is held
 978  */
 979 static void kill_fasync_rcu(struct fasync_struct *fa, int sig, int band)
 980 {
 981         while (fa) {
 982                 struct fown_struct *fown;
 983                 unsigned long flags;
 984
 985                 if (fa->magic != FASYNC_MAGIC) {
 986                         printk(KERN_ERR "kill_fasync: bad magic number in "
 987                                "fasync_struct!\n");
 988                         return;
 989                 }
 990                 spin_lock_irqsave(&fa->fa_lock, flags);
 991                 if (fa->fa_file) {
 992                         fown = &fa->fa_file->f_owner;
 993                         /* Don't send SIGURG to processes which have not set a
 994                            queued signum: SIGURG has its own default signalling
 995                            mechanism. */
 996                         if (!(sig == SIGURG && fown->signum == 0))
 997                                 send_sigio(fown, fa->fa_fd, band);
 998                 }
 999                 spin_unlock_irqrestore(&fa->fa_lock, flags);
1000                 fa = rcu_dereference(fa->fa_next);
1001         }
1002 }
1003
1004 void kill_fasync(struct fasync_struct **fp, int sig, int band)
1005 {
1006         /* First a quick test without locking: usually
1007          * the list is empty.
1008          */
1009         if (*fp) {
1010                 rcu_read_lock();
1011                 kill_fasync_rcu(rcu_dereference(*fp), sig, band);
1012                 rcu_read_unlock();
1013         }
1014 }
1015 EXPORT_SYMBOL(kill_fasync);
1016
1017 static int __init fcntl_init(void)
1018 {
1019         /*
1020          * Please add new bits here to ensure allocation uniqueness.
1021          * Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY
1022          * is defined as O_NONBLOCK on some platforms and not on others.
1023          */
1024         BUILD_BUG_ON(21 - 1 /* for O_RDONLY being 0 */ !=
1025                 HWEIGHT32(
1026                         (VALID_OPEN_FLAGS & ~(O_NONBLOCK | O_NDELAY)) |
1027                         __FMODE_EXEC | __FMODE_NONOTIFY));
1028
1029         fasync_cache = kmem_cache_create("fasync_cache",
1030                 sizeof(struct fasync_struct), 0, SLAB_PANIC, NULL);
1031         return 0;
1032 }
1033
1034 module_init(fcntl_init)