fs/fcntl.c

   1 /*
   2  *  linux/fs/fcntl.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6
   7 #include <linux/syscalls.h>
   8 #include <linux/init.h>
   9 #include <linux/mm.h>
  10 #include <linux/sched/task.h>
  11 #include <linux/fs.h>
  12 #include <linux/file.h>
  13 #include <linux/fdtable.h>
  14 #include <linux/capability.h>
  15 #include <linux/dnotify.h>
  16 #include <linux/slab.h>
  17 #include <linux/module.h>
  18 #include <linux/pipe_fs_i.h>
  19 #include <linux/security.h>
  20 #include <linux/ptrace.h>
  21 #include <linux/signal.h>
  22 #include <linux/rcupdate.h>
  23 #include <linux/pid_namespace.h>
  24 #include <linux/user_namespace.h>
  25 #include <linux/shmem_fs.h>
  26 #include <linux/compat.h>
  27
  28 #include <asm/poll.h>
  29 #include <asm/siginfo.h>
  30 #include <linux/uaccess.h>
  31
  32 #define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT | O_NOATIME)
  33
  34 static int setfl(int fd, struct file * filp, unsigned long arg)
  35 {
  36         struct inode * inode = file_inode(filp);
  37         int error = 0;
  38
  39         /*
  40          * O_APPEND cannot be cleared if the file is marked as append-only
  41          * and the file is open for write.
  42          */
  43         if (((arg ^ filp->f_flags) & O_APPEND) && IS_APPEND(inode))
  44                 return -EPERM;
  45
  46         /* O_NOATIME can only be set by the owner or superuser */
  47         if ((arg & O_NOATIME) && !(filp->f_flags & O_NOATIME))
  48                 if (!inode_owner_or_capable(inode))
  49                         return -EPERM;
  50
  51         /* required for strict SunOS emulation */
  52         if (O_NONBLOCK != O_NDELAY)
  53                if (arg & O_NDELAY)
  54                    arg |= O_NONBLOCK;
  55
  56         /* Pipe packetized mode is controlled by O_DIRECT flag */
  57         if (!S_ISFIFO(inode->i_mode) && (arg & O_DIRECT)) {
  58                 if (!filp->f_mapping || !filp->f_mapping->a_ops ||
  59                         !filp->f_mapping->a_ops->direct_IO)
  60                                 return -EINVAL;
  61         }
  62
  63         if (filp->f_op->check_flags)
  64                 error = filp->f_op->check_flags(arg);
  65         if (error)
  66                 return error;
  67
  68         /*
  69          * ->fasync() is responsible for setting the FASYNC bit.
  70          */
  71         if (((arg ^ filp->f_flags) & FASYNC) && filp->f_op->fasync) {
  72                 error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0);
  73                 if (error < 0)
  74                         goto out;
  75                 if (error > 0)
  76                         error = 0;
  77         }
  78         spin_lock(&filp->f_lock);
  79         filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK);
  80         spin_unlock(&filp->f_lock);
  81
  82  out:
  83         return error;
  84 }
  85
  86 static void f_modown(struct file *filp, struct pid *pid, enum pid_type type,
  87                      int force)
  88 {
  89         write_lock_irq(&filp->f_owner.lock);
  90         if (force || !filp->f_owner.pid) {
  91                 put_pid(filp->f_owner.pid);
  92                 filp->f_owner.pid = get_pid(pid);
  93                 filp->f_owner.pid_type = type;
  94
  95                 if (pid) {
  96                         const struct cred *cred = current_cred();
  97                         filp->f_owner.uid = cred->uid;
  98                         filp->f_owner.euid = cred->euid;
  99                 }
 100         }
 101         write_unlock_irq(&filp->f_owner.lock);
 102 }
 103
 104 void __f_setown(struct file *filp, struct pid *pid, enum pid_type type,
 105                 int force)
 106 {
 107         security_file_set_fowner(filp);
 108         f_modown(filp, pid, type, force);
 109 }
 110 EXPORT_SYMBOL(__f_setown);
 111
 112 int f_setown(struct file *filp, unsigned long arg, int force)
 113 {
 114         enum pid_type type;
 115         struct pid *pid = NULL;
 116         int who = arg, ret = 0;
 117
 118         type = PIDTYPE_PID;
 119         if (who < 0) {
 120                 /* avoid overflow below */
 121                 if (who == INT_MIN)
 122                         return -EINVAL;
 123
 124                 type = PIDTYPE_PGID;
 125                 who = -who;
 126         }
 127
 128         rcu_read_lock();
 129         if (who) {
 130                 pid = find_vpid(who);
 131                 if (!pid)
 132                         ret = -ESRCH;
 133         }
 134
 135         if (!ret)
 136                 __f_setown(filp, pid, type, force);
 137         rcu_read_unlock();
 138
 139         return ret;
 140 }
 141 EXPORT_SYMBOL(f_setown);
 142
 143 void f_delown(struct file *filp)
 144 {
 145         f_modown(filp, NULL, PIDTYPE_PID, 1);
 146 }
 147
 148 pid_t f_getown(struct file *filp)
 149 {
 150         pid_t pid;
 151         read_lock(&filp->f_owner.lock);
 152         pid = pid_vnr(filp->f_owner.pid);
 153         if (filp->f_owner.pid_type == PIDTYPE_PGID)
 154                 pid = -pid;
 155         read_unlock(&filp->f_owner.lock);
 156         return pid;
 157 }
 158
 159 static int f_setown_ex(struct file *filp, unsigned long arg)
 160 {
 161         struct f_owner_ex __user *owner_p = (void __user *)arg;
 162         struct f_owner_ex owner;
 163         struct pid *pid;
 164         int type;
 165         int ret;
 166
 167         ret = copy_from_user(&owner, owner_p, sizeof(owner));
 168         if (ret)
 169                 return -EFAULT;
 170
 171         switch (owner.type) {
 172         case F_OWNER_TID:
 173                 type = PIDTYPE_MAX;
 174                 break;
 175
 176         case F_OWNER_PID:
 177                 type = PIDTYPE_PID;
 178                 break;
 179
 180         case F_OWNER_PGRP:
 181                 type = PIDTYPE_PGID;
 182                 break;
 183
 184         default:
 185                 return -EINVAL;
 186         }
 187
 188         rcu_read_lock();
 189         pid = find_vpid(owner.pid);
 190         if (owner.pid && !pid)
 191                 ret = -ESRCH;
 192         else
 193                  __f_setown(filp, pid, type, 1);
 194         rcu_read_unlock();
 195
 196         return ret;
 197 }
 198
 199 static int f_getown_ex(struct file *filp, unsigned long arg)
 200 {
 201         struct f_owner_ex __user *owner_p = (void __user *)arg;
 202         struct f_owner_ex owner;
 203         int ret = 0;
 204
 205         read_lock(&filp->f_owner.lock);
 206         owner.pid = pid_vnr(filp->f_owner.pid);
 207         switch (filp->f_owner.pid_type) {
 208         case PIDTYPE_MAX:
 209                 owner.type = F_OWNER_TID;
 210                 break;
 211
 212         case PIDTYPE_PID:
 213                 owner.type = F_OWNER_PID;
 214                 break;
 215
 216         case PIDTYPE_PGID:
 217                 owner.type = F_OWNER_PGRP;
 218                 break;
 219
 220         default:
 221                 WARN_ON(1);
 222                 ret = -EINVAL;
 223                 break;
 224         }
 225         read_unlock(&filp->f_owner.lock);
 226
 227         if (!ret) {
 228                 ret = copy_to_user(owner_p, &owner, sizeof(owner));
 229                 if (ret)
 230                         ret = -EFAULT;
 231         }
 232         return ret;
 233 }
 234
 235 #ifdef CONFIG_CHECKPOINT_RESTORE
 236 static int f_getowner_uids(struct file *filp, unsigned long arg)
 237 {
 238         struct user_namespace *user_ns = current_user_ns();
 239         uid_t __user *dst = (void __user *)arg;
 240         uid_t src[2];
 241         int err;
 242
 243         read_lock(&filp->f_owner.lock);
 244         src[0] = from_kuid(user_ns, filp->f_owner.uid);
 245         src[1] = from_kuid(user_ns, filp->f_owner.euid);
 246         read_unlock(&filp->f_owner.lock);
 247
 248         err  = put_user(src[0], &dst[0]);
 249         err |= put_user(src[1], &dst[1]);
 250
 251         return err;
 252 }
 253 #else
 254 static int f_getowner_uids(struct file *filp, unsigned long arg)
 255 {
 256         return -EINVAL;
 257 }
 258 #endif
 259
 260 static bool rw_hint_valid(enum rw_hint hint)
 261 {
 262         switch (hint) {
 263         case RWF_WRITE_LIFE_NOT_SET:
 264         case RWH_WRITE_LIFE_NONE:
 265         case RWH_WRITE_LIFE_SHORT:
 266         case RWH_WRITE_LIFE_MEDIUM:
 267         case RWH_WRITE_LIFE_LONG:
 268         case RWH_WRITE_LIFE_EXTREME:
 269                 return true;
 270         default:
 271                 return false;
 272         }
 273 }
 274
 275 static long fcntl_rw_hint(struct file *file, unsigned int cmd,
 276                           unsigned long arg)
 277 {
 278         struct inode *inode = file_inode(file);
 279         u64 *argp = (u64 __user *)arg;
 280         enum rw_hint hint;
 281         u64 h;
 282
 283         switch (cmd) {
 284         case F_GET_FILE_RW_HINT:
 285                 h = file_write_hint(file);
 286                 if (copy_to_user(argp, &h, sizeof(*argp)))
 287                         return -EFAULT;
 288                 return 0;
 289         case F_SET_FILE_RW_HINT:
 290                 if (copy_from_user(&h, argp, sizeof(h)))
 291                         return -EFAULT;
 292                 hint = (enum rw_hint) h;
 293                 if (!rw_hint_valid(hint))
 294                         return -EINVAL;
 295
 296                 spin_lock(&file->f_lock);
 297                 file->f_write_hint = hint;
 298                 spin_unlock(&file->f_lock);
 299                 return 0;
 300         case F_GET_RW_HINT:
 301                 h = inode->i_write_hint;
 302                 if (copy_to_user(argp, &h, sizeof(*argp)))
 303                         return -EFAULT;
 304                 return 0;
 305         case F_SET_RW_HINT:
 306                 if (copy_from_user(&h, argp, sizeof(h)))
 307                         return -EFAULT;
 308                 hint = (enum rw_hint) h;
 309                 if (!rw_hint_valid(hint))
 310                         return -EINVAL;
 311
 312                 inode_lock(inode);
 313                 inode->i_write_hint = hint;
 314                 inode_unlock(inode);
 315                 return 0;
 316         default:
 317                 return -EINVAL;
 318         }
 319 }
 320
 321 static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
 322                 struct file *filp)
 323 {
 324         void __user *argp = (void __user *)arg;
 325         struct flock flock;
 326         long err = -EINVAL;
 327
 328         switch (cmd) {
 329         case F_DUPFD:
 330                 err = f_dupfd(arg, filp, 0);
 331                 break;
 332         case F_DUPFD_CLOEXEC:
 333                 err = f_dupfd(arg, filp, O_CLOEXEC);
 334                 break;
 335         case F_GETFD:
 336                 err = get_close_on_exec(fd) ? FD_CLOEXEC : 0;
 337                 break;
 338         case F_SETFD:
 339                 err = 0;
 340                 set_close_on_exec(fd, arg & FD_CLOEXEC);
 341                 break;
 342         case F_GETFL:
 343                 err = filp->f_flags;
 344                 break;
 345         case F_SETFL:
 346                 err = setfl(fd, filp, arg);
 347                 break;
 348 #if BITS_PER_LONG != 32
 349         /* 32-bit arches must use fcntl64() */
 350         case F_OFD_GETLK:
 351 #endif
 352         case F_GETLK:
 353                 if (copy_from_user(&flock, argp, sizeof(flock)))
 354                         return -EFAULT;
 355                 err = fcntl_getlk(filp, cmd, &flock);
 356                 if (!err && copy_to_user(argp, &flock, sizeof(flock)))
 357                         return -EFAULT;
 358                 break;
 359 #if BITS_PER_LONG != 32
 360         /* 32-bit arches must use fcntl64() */
 361         case F_OFD_SETLK:
 362         case F_OFD_SETLKW:
 363 #endif
 364                 /* Fallthrough */
 365         case F_SETLK:
 366         case F_SETLKW:
 367                 if (copy_from_user(&flock, argp, sizeof(flock)))
 368                         return -EFAULT;
 369                 err = fcntl_setlk(fd, filp, cmd, &flock);
 370                 break;
 371         case F_GETOWN:
 372                 /*
 373                  * XXX If f_owner is a process group, the
 374                  * negative return value will get converted
 375                  * into an error.  Oops.  If we keep the
 376                  * current syscall conventions, the only way
 377                  * to fix this will be in libc.
 378                  */
 379                 err = f_getown(filp);
 380                 force_successful_syscall_return();
 381                 break;
 382         case F_SETOWN:
 383                 err = f_setown(filp, arg, 1);
 384                 break;
 385         case F_GETOWN_EX:
 386                 err = f_getown_ex(filp, arg);
 387                 break;
 388         case F_SETOWN_EX:
 389                 err = f_setown_ex(filp, arg);
 390                 break;
 391         case F_GETOWNER_UIDS:
 392                 err = f_getowner_uids(filp, arg);
 393                 break;
 394         case F_GETSIG:
 395                 err = filp->f_owner.signum;
 396                 break;
 397         case F_SETSIG:
 398                 /* arg == 0 restores default behaviour. */
 399                 if (!valid_signal(arg)) {
 400                         break;
 401                 }
 402                 err = 0;
 403                 filp->f_owner.signum = arg;
 404                 break;
 405         case F_GETLEASE:
 406                 err = fcntl_getlease(filp);
 407                 break;
 408         case F_SETLEASE:
 409                 err = fcntl_setlease(fd, filp, arg);
 410                 break;
 411         case F_NOTIFY:
 412                 err = fcntl_dirnotify(fd, filp, arg);
 413                 break;
 414         case F_SETPIPE_SZ:
 415         case F_GETPIPE_SZ:
 416                 err = pipe_fcntl(filp, cmd, arg);
 417                 break;
 418         case F_ADD_SEALS:
 419         case F_GET_SEALS:
 420                 err = shmem_fcntl(filp, cmd, arg);
 421                 break;
 422         case F_GET_RW_HINT:
 423         case F_SET_RW_HINT:
 424         case F_GET_FILE_RW_HINT:
 425         case F_SET_FILE_RW_HINT:
 426                 err = fcntl_rw_hint(filp, cmd, arg);
 427                 break;
 428         default:
 429                 break;
 430         }
 431         return err;
 432 }
 433
 434 static int check_fcntl_cmd(unsigned cmd)
 435 {
 436         switch (cmd) {
 437         case F_DUPFD:
 438         case F_DUPFD_CLOEXEC:
 439         case F_GETFD:
 440         case F_SETFD:
 441         case F_GETFL:
 442                 return 1;
 443         }
 444         return 0;
 445 }
 446
 447 SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
 448 {
 449         struct fd f = fdget_raw(fd);
 450         long err = -EBADF;
 451
 452         if (!f.file)
 453                 goto out;
 454
 455         if (unlikely(f.file->f_mode & FMODE_PATH)) {
 456                 if (!check_fcntl_cmd(cmd))
 457                         goto out1;
 458         }
 459
 460         err = security_file_fcntl(f.file, cmd, arg);
 461         if (!err)
 462                 err = do_fcntl(fd, cmd, arg, f.file);
 463
 464 out1:
 465         fdput(f);
 466 out:
 467         return err;
 468 }
 469
 470 #if BITS_PER_LONG == 32
 471 SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd,
 472                 unsigned long, arg)
 473 {
 474         void __user *argp = (void __user *)arg;
 475         struct fd f = fdget_raw(fd);
 476         struct flock64 flock;
 477         long err = -EBADF;
 478
 479         if (!f.file)
 480                 goto out;
 481
 482         if (unlikely(f.file->f_mode & FMODE_PATH)) {
 483                 if (!check_fcntl_cmd(cmd))
 484                         goto out1;
 485         }
 486
 487         err = security_file_fcntl(f.file, cmd, arg);
 488         if (err)
 489                 goto out1;
 490
 491         switch (cmd) {
 492         case F_GETLK64:
 493         case F_OFD_GETLK:
 494                 err = -EFAULT;
 495                 if (copy_from_user(&flock, argp, sizeof(flock)))
 496                         break;
 497                 err = fcntl_getlk64(f.file, cmd, &flock);
 498                 if (!err && copy_to_user(argp, &flock, sizeof(flock)))
 499                         err = -EFAULT;
 500                 break;
 501         case F_SETLK64:
 502         case F_SETLKW64:
 503         case F_OFD_SETLK:
 504         case F_OFD_SETLKW:
 505                 err = -EFAULT;
 506                 if (copy_from_user(&flock, argp, sizeof(flock)))
 507                         break;
 508                 err = fcntl_setlk64(fd, f.file, cmd, &flock);
 509                 break;
 510         default:
 511                 err = do_fcntl(fd, cmd, arg, f.file);
 512                 break;
 513         }
 514 out1:
 515         fdput(f);
 516 out:
 517         return err;
 518 }
 519 #endif
 520
 521 #ifdef CONFIG_COMPAT
 522 /* careful - don't use anywhere else */
 523 #define copy_flock_fields(dst, src)             \
 524         (dst)->l_type = (src)->l_type;          \
 525         (dst)->l_whence = (src)->l_whence;      \
 526         (dst)->l_start = (src)->l_start;        \
 527         (dst)->l_len = (src)->l_len;            \
 528         (dst)->l_pid = (src)->l_pid;
 529
 530 static int get_compat_flock(struct flock *kfl, const struct compat_flock __user *ufl)
 531 {
 532         struct compat_flock fl;
 533
 534         if (copy_from_user(&fl, ufl, sizeof(struct compat_flock)))
 535                 return -EFAULT;
 536         copy_flock_fields(kfl, &fl);
 537         return 0;
 538 }
 539
 540 static int get_compat_flock64(struct flock *kfl, const struct compat_flock64 __user *ufl)
 541 {
 542         struct compat_flock64 fl;
 543
 544         if (copy_from_user(&fl, ufl, sizeof(struct compat_flock64)))
 545                 return -EFAULT;
 546         copy_flock_fields(kfl, &fl);
 547         return 0;
 548 }
 549
 550 static int put_compat_flock(const struct flock *kfl, struct compat_flock __user *ufl)
 551 {
 552         struct compat_flock fl;
 553
 554         memset(&fl, 0, sizeof(struct compat_flock));
 555         copy_flock_fields(&fl, kfl);
 556         if (copy_to_user(ufl, &fl, sizeof(struct compat_flock)))
 557                 return -EFAULT;
 558         return 0;
 559 }
 560
 561 static int put_compat_flock64(const struct flock *kfl, struct compat_flock64 __user *ufl)
 562 {
 563         struct compat_flock64 fl;
 564
 565         memset(&fl, 0, sizeof(struct compat_flock64));
 566         copy_flock_fields(&fl, kfl);
 567         if (copy_to_user(ufl, &fl, sizeof(struct compat_flock64)))
 568                 return -EFAULT;
 569         return 0;
 570 }
 571 #undef copy_flock_fields
 572
 573 static unsigned int
 574 convert_fcntl_cmd(unsigned int cmd)
 575 {
 576         switch (cmd) {
 577         case F_GETLK64:
 578                 return F_GETLK;
 579         case F_SETLK64:
 580                 return F_SETLK;
 581         case F_SETLKW64:
 582                 return F_SETLKW;
 583         }
 584
 585         return cmd;
 586 }
 587
 588 /*
 589  * GETLK was successful and we need to return the data, but it needs to fit in
 590  * the compat structure.
 591  * l_start shouldn't be too big, unless the original start + end is greater than
 592  * COMPAT_OFF_T_MAX, in which case the app was asking for trouble, so we return
 593  * -EOVERFLOW in that case.  l_len could be too big, in which case we just
 594  * truncate it, and only allow the app to see that part of the conflicting lock
 595  * that might make sense to it anyway
 596  */
 597 static int fixup_compat_flock(struct flock *flock)
 598 {
 599         if (flock->l_start > COMPAT_OFF_T_MAX)
 600                 return -EOVERFLOW;
 601         if (flock->l_len > COMPAT_OFF_T_MAX)
 602                 flock->l_len = COMPAT_OFF_T_MAX;
 603         return 0;
 604 }
 605
 606 COMPAT_SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd,
 607                        compat_ulong_t, arg)
 608 {
 609         struct fd f = fdget_raw(fd);
 610         struct flock flock;
 611         long err = -EBADF;
 612
 613         if (!f.file)
 614                 return err;
 615
 616         if (unlikely(f.file->f_mode & FMODE_PATH)) {
 617                 if (!check_fcntl_cmd(cmd))
 618                         goto out_put;
 619         }
 620
 621         err = security_file_fcntl(f.file, cmd, arg);
 622         if (err)
 623                 goto out_put;
 624
 625         switch (cmd) {
 626         case F_GETLK:
 627                 err = get_compat_flock(&flock, compat_ptr(arg));
 628                 if (err)
 629                         break;
 630                 err = fcntl_getlk(f.file, convert_fcntl_cmd(cmd), &flock);
 631                 if (err)
 632                         break;
 633                 err = fixup_compat_flock(&flock);
 634                 if (err)
 635                         return err;
 636                 err = put_compat_flock(&flock, compat_ptr(arg));
 637                 break;
 638         case F_GETLK64:
 639         case F_OFD_GETLK:
 640                 err = get_compat_flock64(&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                         return err;
 649                 err = put_compat_flock64(&flock, compat_ptr(arg));
 650                 break;
 651         case F_SETLK:
 652         case F_SETLKW:
 653                 err = get_compat_flock(&flock, compat_ptr(arg));
 654                 if (err)
 655                         break;
 656                 err = fcntl_setlk(fd, f.file, convert_fcntl_cmd(cmd), &flock);
 657                 break;
 658         case F_SETLK64:
 659         case F_SETLKW64:
 660         case F_OFD_SETLK:
 661         case F_OFD_SETLKW:
 662                 err = get_compat_flock64(&flock, compat_ptr(arg));
 663                 if (err)
 664                         break;
 665                 err = fcntl_setlk(fd, f.file, convert_fcntl_cmd(cmd), &flock);
 666                 break;
 667         default:
 668                 err = do_fcntl(fd, cmd, arg, f.file);
 669                 break;
 670         }
 671 out_put:
 672         fdput(f);
 673         return err;
 674 }
 675
 676 COMPAT_SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd,
 677                        compat_ulong_t, arg)
 678 {
 679         switch (cmd) {
 680         case F_GETLK64:
 681         case F_SETLK64:
 682         case F_SETLKW64:
 683         case F_OFD_GETLK:
 684         case F_OFD_SETLK:
 685         case F_OFD_SETLKW:
 686                 return -EINVAL;
 687         }
 688         return compat_sys_fcntl64(fd, cmd, arg);
 689 }
 690 #endif
 691
 692 /* Table to convert sigio signal codes into poll band bitmaps */
 693
 694 static const long band_table[NSIGPOLL] = {
 695         POLLIN | POLLRDNORM,                    /* POLL_IN */
 696         POLLOUT | POLLWRNORM | POLLWRBAND,      /* POLL_OUT */
 697         POLLIN | POLLRDNORM | POLLMSG,          /* POLL_MSG */
 698         POLLERR,                                /* POLL_ERR */
 699         POLLPRI | POLLRDBAND,                   /* POLL_PRI */
 700         POLLHUP | POLLERR                       /* POLL_HUP */
 701 };
 702
 703 static inline int sigio_perm(struct task_struct *p,
 704                              struct fown_struct *fown, int sig)
 705 {
 706         const struct cred *cred;
 707         int ret;
 708
 709         rcu_read_lock();
 710         cred = __task_cred(p);
 711         ret = ((uid_eq(fown->euid, GLOBAL_ROOT_UID) ||
 712                 uid_eq(fown->euid, cred->suid) || uid_eq(fown->euid, cred->uid) ||
 713                 uid_eq(fown->uid,  cred->suid) || uid_eq(fown->uid,  cred->uid)) &&
 714                !security_file_send_sigiotask(p, fown, sig));
 715         rcu_read_unlock();
 716         return ret;
 717 }
 718
 719 static void send_sigio_to_task(struct task_struct *p,
 720                                struct fown_struct *fown,
 721                                int fd, int reason, int group)
 722 {
 723         /*
 724          * F_SETSIG can change ->signum lockless in parallel, make
 725          * sure we read it once and use the same value throughout.
 726          */
 727         int signum = ACCESS_ONCE(fown->signum);
 728
 729         if (!sigio_perm(p, fown, signum))
 730                 return;
 731
 732         switch (signum) {
 733                 siginfo_t si;
 734                 default:
 735                         /* Queue a rt signal with the appropriate fd as its
 736                            value.  We use SI_SIGIO as the source, not
 737                            SI_KERNEL, since kernel signals always get
 738                            delivered even if we can't queue.  Failure to
 739                            queue in this case _should_ be reported; we fall
 740                            back to SIGIO in that case. --sct */
 741                         si.si_signo = signum;
 742                         si.si_errno = 0;
 743                         si.si_code  = reason;
 744                         /* Make sure we are called with one of the POLL_*
 745                            reasons, otherwise we could leak kernel stack into
 746                            userspace.  */
 747                         BUG_ON((reason & __SI_MASK) != __SI_POLL);
 748                         if (reason - POLL_IN >= NSIGPOLL)
 749                                 si.si_band  = ~0L;
 750                         else
 751                                 si.si_band = band_table[reason - POLL_IN];
 752                         si.si_fd    = fd;
 753                         if (!do_send_sig_info(signum, &si, p, group))
 754                                 break;
 755                 /* fall-through: fall back on the old plain SIGIO signal */
 756                 case 0:
 757                         do_send_sig_info(SIGIO, SEND_SIG_PRIV, p, group);
 758         }
 759 }
 760
 761 void send_sigio(struct fown_struct *fown, int fd, int band)
 762 {
 763         struct task_struct *p;
 764         enum pid_type type;
 765         struct pid *pid;
 766         int group = 1;
 767
 768         read_lock(&fown->lock);
 769
 770         type = fown->pid_type;
 771         if (type == PIDTYPE_MAX) {
 772                 group = 0;
 773                 type = PIDTYPE_PID;
 774         }
 775
 776         pid = fown->pid;
 777         if (!pid)
 778                 goto out_unlock_fown;
 779
 780         read_lock(&tasklist_lock);
 781         do_each_pid_task(pid, type, p) {
 782                 send_sigio_to_task(p, fown, fd, band, group);
 783         } while_each_pid_task(pid, type, p);
 784         read_unlock(&tasklist_lock);
 785  out_unlock_fown:
 786         read_unlock(&fown->lock);
 787 }
 788
 789 static void send_sigurg_to_task(struct task_struct *p,
 790                                 struct fown_struct *fown, int group)
 791 {
 792         if (sigio_perm(p, fown, SIGURG))
 793                 do_send_sig_info(SIGURG, SEND_SIG_PRIV, p, group);
 794 }
 795
 796 int send_sigurg(struct fown_struct *fown)
 797 {
 798         struct task_struct *p;
 799         enum pid_type type;
 800         struct pid *pid;
 801         int group = 1;
 802         int ret = 0;
 803
 804         read_lock(&fown->lock);
 805
 806         type = fown->pid_type;
 807         if (type == PIDTYPE_MAX) {
 808                 group = 0;
 809                 type = PIDTYPE_PID;
 810         }
 811
 812         pid = fown->pid;
 813         if (!pid)
 814                 goto out_unlock_fown;
 815
 816         ret = 1;
 817
 818         read_lock(&tasklist_lock);
 819         do_each_pid_task(pid, type, p) {
 820                 send_sigurg_to_task(p, fown, group);
 821         } while_each_pid_task(pid, type, p);
 822         read_unlock(&tasklist_lock);
 823  out_unlock_fown:
 824         read_unlock(&fown->lock);
 825         return ret;
 826 }
 827
 828 static DEFINE_SPINLOCK(fasync_lock);
 829 static struct kmem_cache *fasync_cache __read_mostly;
 830
 831 static void fasync_free_rcu(struct rcu_head *head)
 832 {
 833         kmem_cache_free(fasync_cache,
 834                         container_of(head, struct fasync_struct, fa_rcu));
 835 }
 836
 837 /*
 838  * Remove a fasync entry. If successfully removed, return
 839  * positive and clear the FASYNC flag. If no entry exists,
 840  * do nothing and return 0.
 841  *
 842  * NOTE! It is very important that the FASYNC flag always
 843  * match the state "is the filp on a fasync list".
 844  *
 845  */
 846 int fasync_remove_entry(struct file *filp, struct fasync_struct **fapp)
 847 {
 848         struct fasync_struct *fa, **fp;
 849         int result = 0;
 850
 851         spin_lock(&filp->f_lock);
 852         spin_lock(&fasync_lock);
 853         for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
 854                 if (fa->fa_file != filp)
 855                         continue;
 856
 857                 spin_lock_irq(&fa->fa_lock);
 858                 fa->fa_file = NULL;
 859                 spin_unlock_irq(&fa->fa_lock);
 860
 861                 *fp = fa->fa_next;
 862                 call_rcu(&fa->fa_rcu, fasync_free_rcu);
 863                 filp->f_flags &= ~FASYNC;
 864                 result = 1;
 865                 break;
 866         }
 867         spin_unlock(&fasync_lock);
 868         spin_unlock(&filp->f_lock);
 869         return result;
 870 }
 871
 872 struct fasync_struct *fasync_alloc(void)
 873 {
 874         return kmem_cache_alloc(fasync_cache, GFP_KERNEL);
 875 }
 876
 877 /*
 878  * NOTE! This can be used only for unused fasync entries:
 879  * entries that actually got inserted on the fasync list
 880  * need to be released by rcu - see fasync_remove_entry.
 881  */
 882 void fasync_free(struct fasync_struct *new)
 883 {
 884         kmem_cache_free(fasync_cache, new);
 885 }
 886
 887 /*
 888  * Insert a new entry into the fasync list.  Return the pointer to the
 889  * old one if we didn't use the new one.
 890  *
 891  * NOTE! It is very important that the FASYNC flag always
 892  * match the state "is the filp on a fasync list".
 893  */
 894 struct fasync_struct *fasync_insert_entry(int fd, struct file *filp, struct fasync_struct **fapp, struct fasync_struct *new)
 895 {
 896         struct fasync_struct *fa, **fp;
 897
 898         spin_lock(&filp->f_lock);
 899         spin_lock(&fasync_lock);
 900         for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
 901                 if (fa->fa_file != filp)
 902                         continue;
 903
 904                 spin_lock_irq(&fa->fa_lock);
 905                 fa->fa_fd = fd;
 906                 spin_unlock_irq(&fa->fa_lock);
 907                 goto out;
 908         }
 909
 910         spin_lock_init(&new->fa_lock);
 911         new->magic = FASYNC_MAGIC;
 912         new->fa_file = filp;
 913         new->fa_fd = fd;
 914         new->fa_next = *fapp;
 915         rcu_assign_pointer(*fapp, new);
 916         filp->f_flags |= FASYNC;
 917
 918 out:
 919         spin_unlock(&fasync_lock);
 920         spin_unlock(&filp->f_lock);
 921         return fa;
 922 }
 923
 924 /*
 925  * Add a fasync entry. Return negative on error, positive if
 926  * added, and zero if did nothing but change an existing one.
 927  */
 928 static int fasync_add_entry(int fd, struct file *filp, struct fasync_struct **fapp)
 929 {
 930         struct fasync_struct *new;
 931
 932         new = fasync_alloc();
 933         if (!new)
 934                 return -ENOMEM;
 935
 936         /*
 937          * fasync_insert_entry() returns the old (update) entry if
 938          * it existed.
 939          *
 940          * So free the (unused) new entry and return 0 to let the
 941          * caller know that we didn't add any new fasync entries.
 942          */
 943         if (fasync_insert_entry(fd, filp, fapp, new)) {
 944                 fasync_free(new);
 945                 return 0;
 946         }
 947
 948         return 1;
 949 }
 950
 951 /*
 952  * fasync_helper() is used by almost all character device drivers
 953  * to set up the fasync queue, and for regular files by the file
 954  * lease code. It returns negative on error, 0 if it did no changes
 955  * and positive if it added/deleted the entry.
 956  */
 957 int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp)
 958 {
 959         if (!on)
 960                 return fasync_remove_entry(filp, fapp);
 961         return fasync_add_entry(fd, filp, fapp);
 962 }
 963
 964 EXPORT_SYMBOL(fasync_helper);
 965
 966 /*
 967  * rcu_read_lock() is held
 968  */
 969 static void kill_fasync_rcu(struct fasync_struct *fa, int sig, int band)
 970 {
 971         while (fa) {
 972                 struct fown_struct *fown;
 973                 unsigned long flags;
 974
 975                 if (fa->magic != FASYNC_MAGIC) {
 976                         printk(KERN_ERR "kill_fasync: bad magic number in "
 977                                "fasync_struct!\n");
 978                         return;
 979                 }
 980                 spin_lock_irqsave(&fa->fa_lock, flags);
 981                 if (fa->fa_file) {
 982                         fown = &fa->fa_file->f_owner;
 983                         /* Don't send SIGURG to processes which have not set a
 984                            queued signum: SIGURG has its own default signalling
 985                            mechanism. */
 986                         if (!(sig == SIGURG && fown->signum == 0))
 987                                 send_sigio(fown, fa->fa_fd, band);
 988                 }
 989                 spin_unlock_irqrestore(&fa->fa_lock, flags);
 990                 fa = rcu_dereference(fa->fa_next);
 991         }
 992 }
 993
 994 void kill_fasync(struct fasync_struct **fp, int sig, int band)
 995 {
 996         /* First a quick test without locking: usually
 997          * the list is empty.
 998          */
 999         if (*fp) {
1000                 rcu_read_lock();
1001                 kill_fasync_rcu(rcu_dereference(*fp), sig, band);
1002                 rcu_read_unlock();
1003         }
1004 }
1005 EXPORT_SYMBOL(kill_fasync);
1006
1007 static int __init fcntl_init(void)
1008 {
1009         /*
1010          * Please add new bits here to ensure allocation uniqueness.
1011          * Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY
1012          * is defined as O_NONBLOCK on some platforms and not on others.
1013          */
1014         BUILD_BUG_ON(21 - 1 /* for O_RDONLY being 0 */ !=
1015                 HWEIGHT32(
1016                         (VALID_OPEN_FLAGS & ~(O_NONBLOCK | O_NDELAY)) |
1017                         __FMODE_EXEC | __FMODE_NONOTIFY));
1018
1019         fasync_cache = kmem_cache_create("fasync_cache",
1020                 sizeof(struct fasync_struct), 0, SLAB_PANIC, NULL);
1021         return 0;
1022 }
1023
1024 module_init(fcntl_init)