| 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/filelock.h> |
| 14 | #include <linux/file.h> |
| 15 | #include <linux/fdtable.h> |
| 16 | #include <linux/capability.h> |
| 17 | #include <linux/dnotify.h> |
| 18 | #include <linux/slab.h> |
| 19 | #include <linux/module.h> |
| 20 | #include <linux/pipe_fs_i.h> |
| 21 | #include <linux/security.h> |
| 22 | #include <linux/ptrace.h> |
| 23 | #include <linux/signal.h> |
| 24 | #include <linux/rcupdate.h> |
| 25 | #include <linux/pid_namespace.h> |
| 26 | #include <linux/user_namespace.h> |
| 27 | #include <linux/memfd.h> |
| 28 | #include <linux/compat.h> |
| 29 | #include <linux/mount.h> |
| 30 | |
| 31 | #include <linux/poll.h> |
| 32 | #include <asm/siginfo.h> |
| 33 | #include <linux/uaccess.h> |
| 34 | |
| 35 | #define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT | O_NOATIME) |
| 36 | |
| 37 | static int setfl(int fd, struct file * filp, unsigned long arg) |
| 38 | { |
| 39 | struct inode * inode = file_inode(filp); |
| 40 | int error = 0; |
| 41 | |
| 42 | /* |
| 43 | * O_APPEND cannot be cleared if the file is marked as append-only |
| 44 | * and the file is open for write. |
| 45 | */ |
| 46 | if (((arg ^ filp->f_flags) & O_APPEND) && IS_APPEND(inode)) |
| 47 | return -EPERM; |
| 48 | |
| 49 | /* O_NOATIME can only be set by the owner or superuser */ |
| 50 | if ((arg & O_NOATIME) && !(filp->f_flags & O_NOATIME)) |
| 51 | if (!inode_owner_or_capable(file_mnt_idmap(filp), inode)) |
| 52 | return -EPERM; |
| 53 | |
| 54 | /* required for strict SunOS emulation */ |
| 55 | if (O_NONBLOCK != O_NDELAY) |
| 56 | if (arg & O_NDELAY) |
| 57 | arg |= O_NONBLOCK; |
| 58 | |
| 59 | /* Pipe packetized mode is controlled by O_DIRECT flag */ |
| 60 | if (!S_ISFIFO(inode->i_mode) && |
| 61 | (arg & O_DIRECT) && |
| 62 | !(filp->f_mode & FMODE_CAN_ODIRECT)) |
| 63 | return -EINVAL; |
| 64 | |
| 65 | if (filp->f_op->check_flags) |
| 66 | error = filp->f_op->check_flags(arg); |
| 67 | if (error) |
| 68 | return error; |
| 69 | |
| 70 | /* |
| 71 | * ->fasync() is responsible for setting the FASYNC bit. |
| 72 | */ |
| 73 | if (((arg ^ filp->f_flags) & FASYNC) && filp->f_op->fasync) { |
| 74 | error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0); |
| 75 | if (error < 0) |
| 76 | goto out; |
| 77 | if (error > 0) |
| 78 | error = 0; |
| 79 | } |
| 80 | spin_lock(&filp->f_lock); |
| 81 | filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK); |
| 82 | filp->f_iocb_flags = iocb_flags(filp); |
| 83 | spin_unlock(&filp->f_lock); |
| 84 | |
| 85 | out: |
| 86 | return error; |
| 87 | } |
| 88 | |
| 89 | static void f_modown(struct file *filp, struct pid *pid, enum pid_type type, |
| 90 | int force) |
| 91 | { |
| 92 | write_lock_irq(&filp->f_owner.lock); |
| 93 | if (force || !filp->f_owner.pid) { |
| 94 | put_pid(filp->f_owner.pid); |
| 95 | filp->f_owner.pid = get_pid(pid); |
| 96 | filp->f_owner.pid_type = type; |
| 97 | |
| 98 | if (pid) { |
| 99 | const struct cred *cred = current_cred(); |
| 100 | filp->f_owner.uid = cred->uid; |
| 101 | filp->f_owner.euid = cred->euid; |
| 102 | } |
| 103 | } |
| 104 | write_unlock_irq(&filp->f_owner.lock); |
| 105 | } |
| 106 | |
| 107 | void __f_setown(struct file *filp, struct pid *pid, enum pid_type type, |
| 108 | int force) |
| 109 | { |
| 110 | security_file_set_fowner(filp); |
| 111 | f_modown(filp, pid, type, force); |
| 112 | } |
| 113 | EXPORT_SYMBOL(__f_setown); |
| 114 | |
| 115 | int f_setown(struct file *filp, unsigned long arg, int force) |
| 116 | { |
| 117 | enum pid_type type; |
| 118 | struct pid *pid = NULL; |
| 119 | int who = arg, ret = 0; |
| 120 | |
| 121 | type = PIDTYPE_TGID; |
| 122 | if (who < 0) { |
| 123 | /* avoid overflow below */ |
| 124 | if (who == INT_MIN) |
| 125 | return -EINVAL; |
| 126 | |
| 127 | type = PIDTYPE_PGID; |
| 128 | who = -who; |
| 129 | } |
| 130 | |
| 131 | rcu_read_lock(); |
| 132 | if (who) { |
| 133 | pid = find_vpid(who); |
| 134 | if (!pid) |
| 135 | ret = -ESRCH; |
| 136 | } |
| 137 | |
| 138 | if (!ret) |
| 139 | __f_setown(filp, pid, type, force); |
| 140 | rcu_read_unlock(); |
| 141 | |
| 142 | return ret; |
| 143 | } |
| 144 | EXPORT_SYMBOL(f_setown); |
| 145 | |
| 146 | void f_delown(struct file *filp) |
| 147 | { |
| 148 | f_modown(filp, NULL, PIDTYPE_TGID, 1); |
| 149 | } |
| 150 | |
| 151 | pid_t f_getown(struct file *filp) |
| 152 | { |
| 153 | pid_t pid = 0; |
| 154 | |
| 155 | read_lock_irq(&filp->f_owner.lock); |
| 156 | rcu_read_lock(); |
| 157 | if (pid_task(filp->f_owner.pid, filp->f_owner.pid_type)) { |
| 158 | pid = pid_vnr(filp->f_owner.pid); |
| 159 | if (filp->f_owner.pid_type == PIDTYPE_PGID) |
| 160 | pid = -pid; |
| 161 | } |
| 162 | rcu_read_unlock(); |
| 163 | read_unlock_irq(&filp->f_owner.lock); |
| 164 | return pid; |
| 165 | } |
| 166 | |
| 167 | static int f_setown_ex(struct file *filp, unsigned long arg) |
| 168 | { |
| 169 | struct f_owner_ex __user *owner_p = (void __user *)arg; |
| 170 | struct f_owner_ex owner; |
| 171 | struct pid *pid; |
| 172 | int type; |
| 173 | int ret; |
| 174 | |
| 175 | ret = copy_from_user(&owner, owner_p, sizeof(owner)); |
| 176 | if (ret) |
| 177 | return -EFAULT; |
| 178 | |
| 179 | switch (owner.type) { |
| 180 | case F_OWNER_TID: |
| 181 | type = PIDTYPE_PID; |
| 182 | break; |
| 183 | |
| 184 | case F_OWNER_PID: |
| 185 | type = PIDTYPE_TGID; |
| 186 | break; |
| 187 | |
| 188 | case F_OWNER_PGRP: |
| 189 | type = PIDTYPE_PGID; |
| 190 | break; |
| 191 | |
| 192 | default: |
| 193 | return -EINVAL; |
| 194 | } |
| 195 | |
| 196 | rcu_read_lock(); |
| 197 | pid = find_vpid(owner.pid); |
| 198 | if (owner.pid && !pid) |
| 199 | ret = -ESRCH; |
| 200 | else |
| 201 | __f_setown(filp, pid, type, 1); |
| 202 | rcu_read_unlock(); |
| 203 | |
| 204 | return ret; |
| 205 | } |
| 206 | |
| 207 | static int f_getown_ex(struct file *filp, unsigned long arg) |
| 208 | { |
| 209 | struct f_owner_ex __user *owner_p = (void __user *)arg; |
| 210 | struct f_owner_ex owner = {}; |
| 211 | int ret = 0; |
| 212 | |
| 213 | read_lock_irq(&filp->f_owner.lock); |
| 214 | rcu_read_lock(); |
| 215 | if (pid_task(filp->f_owner.pid, filp->f_owner.pid_type)) |
| 216 | owner.pid = pid_vnr(filp->f_owner.pid); |
| 217 | rcu_read_unlock(); |
| 218 | switch (filp->f_owner.pid_type) { |
| 219 | case PIDTYPE_PID: |
| 220 | owner.type = F_OWNER_TID; |
| 221 | break; |
| 222 | |
| 223 | case PIDTYPE_TGID: |
| 224 | owner.type = F_OWNER_PID; |
| 225 | break; |
| 226 | |
| 227 | case PIDTYPE_PGID: |
| 228 | owner.type = F_OWNER_PGRP; |
| 229 | break; |
| 230 | |
| 231 | default: |
| 232 | WARN_ON(1); |
| 233 | ret = -EINVAL; |
| 234 | break; |
| 235 | } |
| 236 | read_unlock_irq(&filp->f_owner.lock); |
| 237 | |
| 238 | if (!ret) { |
| 239 | ret = copy_to_user(owner_p, &owner, sizeof(owner)); |
| 240 | if (ret) |
| 241 | ret = -EFAULT; |
| 242 | } |
| 243 | return ret; |
| 244 | } |
| 245 | |
| 246 | #ifdef CONFIG_CHECKPOINT_RESTORE |
| 247 | static int f_getowner_uids(struct file *filp, unsigned long arg) |
| 248 | { |
| 249 | struct user_namespace *user_ns = current_user_ns(); |
| 250 | uid_t __user *dst = (void __user *)arg; |
| 251 | uid_t src[2]; |
| 252 | int err; |
| 253 | |
| 254 | read_lock_irq(&filp->f_owner.lock); |
| 255 | src[0] = from_kuid(user_ns, filp->f_owner.uid); |
| 256 | src[1] = from_kuid(user_ns, filp->f_owner.euid); |
| 257 | read_unlock_irq(&filp->f_owner.lock); |
| 258 | |
| 259 | err = put_user(src[0], &dst[0]); |
| 260 | err |= put_user(src[1], &dst[1]); |
| 261 | |
| 262 | return err; |
| 263 | } |
| 264 | #else |
| 265 | static int f_getowner_uids(struct file *filp, unsigned long arg) |
| 266 | { |
| 267 | return -EINVAL; |
| 268 | } |
| 269 | #endif |
| 270 | |
| 271 | static bool rw_hint_valid(enum rw_hint hint) |
| 272 | { |
| 273 | switch (hint) { |
| 274 | case RWH_WRITE_LIFE_NOT_SET: |
| 275 | case RWH_WRITE_LIFE_NONE: |
| 276 | case RWH_WRITE_LIFE_SHORT: |
| 277 | case RWH_WRITE_LIFE_MEDIUM: |
| 278 | case RWH_WRITE_LIFE_LONG: |
| 279 | case RWH_WRITE_LIFE_EXTREME: |
| 280 | return true; |
| 281 | default: |
| 282 | return false; |
| 283 | } |
| 284 | } |
| 285 | |
| 286 | static long fcntl_rw_hint(struct file *file, unsigned int cmd, |
| 287 | unsigned long arg) |
| 288 | { |
| 289 | struct inode *inode = file_inode(file); |
| 290 | u64 __user *argp = (u64 __user *)arg; |
| 291 | enum rw_hint hint; |
| 292 | u64 h; |
| 293 | |
| 294 | switch (cmd) { |
| 295 | case F_GET_RW_HINT: |
| 296 | h = inode->i_write_hint; |
| 297 | if (copy_to_user(argp, &h, sizeof(*argp))) |
| 298 | return -EFAULT; |
| 299 | return 0; |
| 300 | case F_SET_RW_HINT: |
| 301 | if (copy_from_user(&h, argp, sizeof(h))) |
| 302 | return -EFAULT; |
| 303 | hint = (enum rw_hint) h; |
| 304 | if (!rw_hint_valid(hint)) |
| 305 | return -EINVAL; |
| 306 | |
| 307 | inode_lock(inode); |
| 308 | inode->i_write_hint = hint; |
| 309 | inode_unlock(inode); |
| 310 | return 0; |
| 311 | default: |
| 312 | return -EINVAL; |
| 313 | } |
| 314 | } |
| 315 | |
| 316 | static long do_fcntl(int fd, unsigned int cmd, unsigned long arg, |
| 317 | struct file *filp) |
| 318 | { |
| 319 | void __user *argp = (void __user *)arg; |
| 320 | struct flock flock; |
| 321 | long err = -EINVAL; |
| 322 | |
| 323 | switch (cmd) { |
| 324 | case F_DUPFD: |
| 325 | err = f_dupfd(arg, filp, 0); |
| 326 | break; |
| 327 | case F_DUPFD_CLOEXEC: |
| 328 | err = f_dupfd(arg, filp, O_CLOEXEC); |
| 329 | break; |
| 330 | case F_GETFD: |
| 331 | err = get_close_on_exec(fd) ? FD_CLOEXEC : 0; |
| 332 | break; |
| 333 | case F_SETFD: |
| 334 | err = 0; |
| 335 | set_close_on_exec(fd, arg & FD_CLOEXEC); |
| 336 | break; |
| 337 | case F_GETFL: |
| 338 | err = filp->f_flags; |
| 339 | break; |
| 340 | case F_SETFL: |
| 341 | err = setfl(fd, filp, arg); |
| 342 | break; |
| 343 | #if BITS_PER_LONG != 32 |
| 344 | /* 32-bit arches must use fcntl64() */ |
| 345 | case F_OFD_GETLK: |
| 346 | #endif |
| 347 | case F_GETLK: |
| 348 | if (copy_from_user(&flock, argp, sizeof(flock))) |
| 349 | return -EFAULT; |
| 350 | err = fcntl_getlk(filp, cmd, &flock); |
| 351 | if (!err && copy_to_user(argp, &flock, sizeof(flock))) |
| 352 | return -EFAULT; |
| 353 | break; |
| 354 | #if BITS_PER_LONG != 32 |
| 355 | /* 32-bit arches must use fcntl64() */ |
| 356 | case F_OFD_SETLK: |
| 357 | case F_OFD_SETLKW: |
| 358 | fallthrough; |
| 359 | #endif |
| 360 | case F_SETLK: |
| 361 | case F_SETLKW: |
| 362 | if (copy_from_user(&flock, argp, sizeof(flock))) |
| 363 | return -EFAULT; |
| 364 | err = fcntl_setlk(fd, filp, cmd, &flock); |
| 365 | break; |
| 366 | case F_GETOWN: |
| 367 | /* |
| 368 | * XXX If f_owner is a process group, the |
| 369 | * negative return value will get converted |
| 370 | * into an error. Oops. If we keep the |
| 371 | * current syscall conventions, the only way |
| 372 | * to fix this will be in libc. |
| 373 | */ |
| 374 | err = f_getown(filp); |
| 375 | force_successful_syscall_return(); |
| 376 | break; |
| 377 | case F_SETOWN: |
| 378 | err = f_setown(filp, arg, 1); |
| 379 | break; |
| 380 | case F_GETOWN_EX: |
| 381 | err = f_getown_ex(filp, arg); |
| 382 | break; |
| 383 | case F_SETOWN_EX: |
| 384 | err = f_setown_ex(filp, arg); |
| 385 | break; |
| 386 | case F_GETOWNER_UIDS: |
| 387 | err = f_getowner_uids(filp, arg); |
| 388 | break; |
| 389 | case F_GETSIG: |
| 390 | err = filp->f_owner.signum; |
| 391 | break; |
| 392 | case F_SETSIG: |
| 393 | /* arg == 0 restores default behaviour. */ |
| 394 | if (!valid_signal(arg)) { |
| 395 | break; |
| 396 | } |
| 397 | err = 0; |
| 398 | filp->f_owner.signum = arg; |
| 399 | break; |
| 400 | case F_GETLEASE: |
| 401 | err = fcntl_getlease(filp); |
| 402 | break; |
| 403 | case F_SETLEASE: |
| 404 | err = fcntl_setlease(fd, filp, arg); |
| 405 | break; |
| 406 | case F_NOTIFY: |
| 407 | err = fcntl_dirnotify(fd, filp, arg); |
| 408 | break; |
| 409 | case F_SETPIPE_SZ: |
| 410 | case F_GETPIPE_SZ: |
| 411 | err = pipe_fcntl(filp, cmd, arg); |
| 412 | break; |
| 413 | case F_ADD_SEALS: |
| 414 | case F_GET_SEALS: |
| 415 | err = memfd_fcntl(filp, cmd, arg); |
| 416 | break; |
| 417 | case F_GET_RW_HINT: |
| 418 | case F_SET_RW_HINT: |
| 419 | err = fcntl_rw_hint(filp, cmd, arg); |
| 420 | break; |
| 421 | default: |
| 422 | break; |
| 423 | } |
| 424 | return err; |
| 425 | } |
| 426 | |
| 427 | static int check_fcntl_cmd(unsigned cmd) |
| 428 | { |
| 429 | switch (cmd) { |
| 430 | case F_DUPFD: |
| 431 | case F_DUPFD_CLOEXEC: |
| 432 | case F_GETFD: |
| 433 | case F_SETFD: |
| 434 | case F_GETFL: |
| 435 | return 1; |
| 436 | } |
| 437 | return 0; |
| 438 | } |
| 439 | |
| 440 | SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg) |
| 441 | { |
| 442 | struct fd f = fdget_raw(fd); |
| 443 | long err = -EBADF; |
| 444 | |
| 445 | if (!f.file) |
| 446 | goto out; |
| 447 | |
| 448 | if (unlikely(f.file->f_mode & FMODE_PATH)) { |
| 449 | if (!check_fcntl_cmd(cmd)) |
| 450 | goto out1; |
| 451 | } |
| 452 | |
| 453 | err = security_file_fcntl(f.file, cmd, arg); |
| 454 | if (!err) |
| 455 | err = do_fcntl(fd, cmd, arg, f.file); |
| 456 | |
| 457 | out1: |
| 458 | fdput(f); |
| 459 | out: |
| 460 | return err; |
| 461 | } |
| 462 | |
| 463 | #if BITS_PER_LONG == 32 |
| 464 | SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd, |
| 465 | unsigned long, arg) |
| 466 | { |
| 467 | void __user *argp = (void __user *)arg; |
| 468 | struct fd f = fdget_raw(fd); |
| 469 | struct flock64 flock; |
| 470 | long err = -EBADF; |
| 471 | |
| 472 | if (!f.file) |
| 473 | goto out; |
| 474 | |
| 475 | if (unlikely(f.file->f_mode & FMODE_PATH)) { |
| 476 | if (!check_fcntl_cmd(cmd)) |
| 477 | goto out1; |
| 478 | } |
| 479 | |
| 480 | err = security_file_fcntl(f.file, cmd, arg); |
| 481 | if (err) |
| 482 | goto out1; |
| 483 | |
| 484 | switch (cmd) { |
| 485 | case F_GETLK64: |
| 486 | case F_OFD_GETLK: |
| 487 | err = -EFAULT; |
| 488 | if (copy_from_user(&flock, argp, sizeof(flock))) |
| 489 | break; |
| 490 | err = fcntl_getlk64(f.file, cmd, &flock); |
| 491 | if (!err && copy_to_user(argp, &flock, sizeof(flock))) |
| 492 | err = -EFAULT; |
| 493 | break; |
| 494 | case F_SETLK64: |
| 495 | case F_SETLKW64: |
| 496 | case F_OFD_SETLK: |
| 497 | case F_OFD_SETLKW: |
| 498 | err = -EFAULT; |
| 499 | if (copy_from_user(&flock, argp, sizeof(flock))) |
| 500 | break; |
| 501 | err = fcntl_setlk64(fd, f.file, cmd, &flock); |
| 502 | break; |
| 503 | default: |
| 504 | err = do_fcntl(fd, cmd, arg, f.file); |
| 505 | break; |
| 506 | } |
| 507 | out1: |
| 508 | fdput(f); |
| 509 | out: |
| 510 | return err; |
| 511 | } |
| 512 | #endif |
| 513 | |
| 514 | #ifdef CONFIG_COMPAT |
| 515 | /* careful - don't use anywhere else */ |
| 516 | #define copy_flock_fields(dst, src) \ |
| 517 | (dst)->l_type = (src)->l_type; \ |
| 518 | (dst)->l_whence = (src)->l_whence; \ |
| 519 | (dst)->l_start = (src)->l_start; \ |
| 520 | (dst)->l_len = (src)->l_len; \ |
| 521 | (dst)->l_pid = (src)->l_pid; |
| 522 | |
| 523 | static int get_compat_flock(struct flock *kfl, const struct compat_flock __user *ufl) |
| 524 | { |
| 525 | struct compat_flock fl; |
| 526 | |
| 527 | if (copy_from_user(&fl, ufl, sizeof(struct compat_flock))) |
| 528 | return -EFAULT; |
| 529 | copy_flock_fields(kfl, &fl); |
| 530 | return 0; |
| 531 | } |
| 532 | |
| 533 | static int get_compat_flock64(struct flock *kfl, const struct compat_flock64 __user *ufl) |
| 534 | { |
| 535 | struct compat_flock64 fl; |
| 536 | |
| 537 | if (copy_from_user(&fl, ufl, sizeof(struct compat_flock64))) |
| 538 | return -EFAULT; |
| 539 | copy_flock_fields(kfl, &fl); |
| 540 | return 0; |
| 541 | } |
| 542 | |
| 543 | static int put_compat_flock(const struct flock *kfl, struct compat_flock __user *ufl) |
| 544 | { |
| 545 | struct compat_flock fl; |
| 546 | |
| 547 | memset(&fl, 0, sizeof(struct compat_flock)); |
| 548 | copy_flock_fields(&fl, kfl); |
| 549 | if (copy_to_user(ufl, &fl, sizeof(struct compat_flock))) |
| 550 | return -EFAULT; |
| 551 | return 0; |
| 552 | } |
| 553 | |
| 554 | static int put_compat_flock64(const struct flock *kfl, struct compat_flock64 __user *ufl) |
| 555 | { |
| 556 | struct compat_flock64 fl; |
| 557 | |
| 558 | BUILD_BUG_ON(sizeof(kfl->l_start) > sizeof(ufl->l_start)); |
| 559 | BUILD_BUG_ON(sizeof(kfl->l_len) > sizeof(ufl->l_len)); |
| 560 | |
| 561 | memset(&fl, 0, sizeof(struct compat_flock64)); |
| 562 | copy_flock_fields(&fl, kfl); |
| 563 | if (copy_to_user(ufl, &fl, sizeof(struct compat_flock64))) |
| 564 | return -EFAULT; |
| 565 | return 0; |
| 566 | } |
| 567 | #undef copy_flock_fields |
| 568 | |
| 569 | static unsigned int |
| 570 | convert_fcntl_cmd(unsigned int cmd) |
| 571 | { |
| 572 | switch (cmd) { |
| 573 | case F_GETLK64: |
| 574 | return F_GETLK; |
| 575 | case F_SETLK64: |
| 576 | return F_SETLK; |
| 577 | case F_SETLKW64: |
| 578 | return F_SETLKW; |
| 579 | } |
| 580 | |
| 581 | return cmd; |
| 582 | } |
| 583 | |
| 584 | /* |
| 585 | * GETLK was successful and we need to return the data, but it needs to fit in |
| 586 | * the compat structure. |
| 587 | * l_start shouldn't be too big, unless the original start + end is greater than |
| 588 | * COMPAT_OFF_T_MAX, in which case the app was asking for trouble, so we return |
| 589 | * -EOVERFLOW in that case. l_len could be too big, in which case we just |
| 590 | * truncate it, and only allow the app to see that part of the conflicting lock |
| 591 | * that might make sense to it anyway |
| 592 | */ |
| 593 | static int fixup_compat_flock(struct flock *flock) |
| 594 | { |
| 595 | if (flock->l_start > COMPAT_OFF_T_MAX) |
| 596 | return -EOVERFLOW; |
| 597 | if (flock->l_len > COMPAT_OFF_T_MAX) |
| 598 | flock->l_len = COMPAT_OFF_T_MAX; |
| 599 | return 0; |
| 600 | } |
| 601 | |
| 602 | static long do_compat_fcntl64(unsigned int fd, unsigned int cmd, |
| 603 | compat_ulong_t arg) |
| 604 | { |
| 605 | struct fd f = fdget_raw(fd); |
| 606 | struct flock flock; |
| 607 | long err = -EBADF; |
| 608 | |
| 609 | if (!f.file) |
| 610 | return err; |
| 611 | |
| 612 | if (unlikely(f.file->f_mode & FMODE_PATH)) { |
| 613 | if (!check_fcntl_cmd(cmd)) |
| 614 | goto out_put; |
| 615 | } |
| 616 | |
| 617 | err = security_file_fcntl(f.file, cmd, arg); |
| 618 | if (err) |
| 619 | goto out_put; |
| 620 | |
| 621 | switch (cmd) { |
| 622 | case F_GETLK: |
| 623 | err = get_compat_flock(&flock, compat_ptr(arg)); |
| 624 | if (err) |
| 625 | break; |
| 626 | err = fcntl_getlk(f.file, convert_fcntl_cmd(cmd), &flock); |
| 627 | if (err) |
| 628 | break; |
| 629 | err = fixup_compat_flock(&flock); |
| 630 | if (!err) |
| 631 | err = put_compat_flock(&flock, compat_ptr(arg)); |
| 632 | break; |
| 633 | case F_GETLK64: |
| 634 | case F_OFD_GETLK: |
| 635 | err = get_compat_flock64(&flock, compat_ptr(arg)); |
| 636 | if (err) |
| 637 | break; |
| 638 | err = fcntl_getlk(f.file, convert_fcntl_cmd(cmd), &flock); |
| 639 | if (!err) |
| 640 | err = put_compat_flock64(&flock, compat_ptr(arg)); |
| 641 | break; |
| 642 | case F_SETLK: |
| 643 | case F_SETLKW: |
| 644 | err = get_compat_flock(&flock, compat_ptr(arg)); |
| 645 | if (err) |
| 646 | break; |
| 647 | err = fcntl_setlk(fd, f.file, convert_fcntl_cmd(cmd), &flock); |
| 648 | break; |
| 649 | case F_SETLK64: |
| 650 | case F_SETLKW64: |
| 651 | case F_OFD_SETLK: |
| 652 | case F_OFD_SETLKW: |
| 653 | err = get_compat_flock64(&flock, compat_ptr(arg)); |
| 654 | if (err) |
| 655 | break; |
| 656 | err = fcntl_setlk(fd, f.file, convert_fcntl_cmd(cmd), &flock); |
| 657 | break; |
| 658 | default: |
| 659 | err = do_fcntl(fd, cmd, arg, f.file); |
| 660 | break; |
| 661 | } |
| 662 | out_put: |
| 663 | fdput(f); |
| 664 | return err; |
| 665 | } |
| 666 | |
| 667 | COMPAT_SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd, |
| 668 | compat_ulong_t, arg) |
| 669 | { |
| 670 | return do_compat_fcntl64(fd, cmd, arg); |
| 671 | } |
| 672 | |
| 673 | COMPAT_SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, |
| 674 | compat_ulong_t, arg) |
| 675 | { |
| 676 | switch (cmd) { |
| 677 | case F_GETLK64: |
| 678 | case F_SETLK64: |
| 679 | case F_SETLKW64: |
| 680 | case F_OFD_GETLK: |
| 681 | case F_OFD_SETLK: |
| 682 | case F_OFD_SETLKW: |
| 683 | return -EINVAL; |
| 684 | } |
| 685 | return do_compat_fcntl64(fd, cmd, arg); |
| 686 | } |
| 687 | #endif |
| 688 | |
| 689 | /* Table to convert sigio signal codes into poll band bitmaps */ |
| 690 | |
| 691 | static const __poll_t band_table[NSIGPOLL] = { |
| 692 | EPOLLIN | EPOLLRDNORM, /* POLL_IN */ |
| 693 | EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND, /* POLL_OUT */ |
| 694 | EPOLLIN | EPOLLRDNORM | EPOLLMSG, /* POLL_MSG */ |
| 695 | EPOLLERR, /* POLL_ERR */ |
| 696 | EPOLLPRI | EPOLLRDBAND, /* POLL_PRI */ |
| 697 | EPOLLHUP | EPOLLERR /* POLL_HUP */ |
| 698 | }; |
| 699 | |
| 700 | static inline int sigio_perm(struct task_struct *p, |
| 701 | struct fown_struct *fown, int sig) |
| 702 | { |
| 703 | const struct cred *cred; |
| 704 | int ret; |
| 705 | |
| 706 | rcu_read_lock(); |
| 707 | cred = __task_cred(p); |
| 708 | ret = ((uid_eq(fown->euid, GLOBAL_ROOT_UID) || |
| 709 | uid_eq(fown->euid, cred->suid) || uid_eq(fown->euid, cred->uid) || |
| 710 | uid_eq(fown->uid, cred->suid) || uid_eq(fown->uid, cred->uid)) && |
| 711 | !security_file_send_sigiotask(p, fown, sig)); |
| 712 | rcu_read_unlock(); |
| 713 | return ret; |
| 714 | } |
| 715 | |
| 716 | static void send_sigio_to_task(struct task_struct *p, |
| 717 | struct fown_struct *fown, |
| 718 | int fd, int reason, enum pid_type type) |
| 719 | { |
| 720 | /* |
| 721 | * F_SETSIG can change ->signum lockless in parallel, make |
| 722 | * sure we read it once and use the same value throughout. |
| 723 | */ |
| 724 | int signum = READ_ONCE(fown->signum); |
| 725 | |
| 726 | if (!sigio_perm(p, fown, signum)) |
| 727 | return; |
| 728 | |
| 729 | switch (signum) { |
| 730 | default: { |
| 731 | kernel_siginfo_t si; |
| 732 | |
| 733 | /* Queue a rt signal with the appropriate fd as its |
| 734 | value. We use SI_SIGIO as the source, not |
| 735 | SI_KERNEL, since kernel signals always get |
| 736 | delivered even if we can't queue. Failure to |
| 737 | queue in this case _should_ be reported; we fall |
| 738 | back to SIGIO in that case. --sct */ |
| 739 | clear_siginfo(&si); |
| 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 = mangle_poll(band_table[reason - POLL_IN]); |
| 762 | si.si_fd = fd; |
| 763 | if (!do_send_sig_info(signum, &si, p, type)) |
| 764 | break; |
| 765 | } |
| 766 | fallthrough; /* fall back on the old plain SIGIO signal */ |
| 767 | case 0: |
| 768 | do_send_sig_info(SIGIO, SEND_SIG_PRIV, p, type); |
| 769 | } |
| 770 | } |
| 771 | |
| 772 | void send_sigio(struct fown_struct *fown, int fd, int band) |
| 773 | { |
| 774 | struct task_struct *p; |
| 775 | enum pid_type type; |
| 776 | unsigned long flags; |
| 777 | struct pid *pid; |
| 778 | |
| 779 | read_lock_irqsave(&fown->lock, flags); |
| 780 | |
| 781 | type = fown->pid_type; |
| 782 | pid = fown->pid; |
| 783 | if (!pid) |
| 784 | goto out_unlock_fown; |
| 785 | |
| 786 | if (type <= PIDTYPE_TGID) { |
| 787 | rcu_read_lock(); |
| 788 | p = pid_task(pid, PIDTYPE_PID); |
| 789 | if (p) |
| 790 | send_sigio_to_task(p, fown, fd, band, type); |
| 791 | rcu_read_unlock(); |
| 792 | } else { |
| 793 | read_lock(&tasklist_lock); |
| 794 | do_each_pid_task(pid, type, p) { |
| 795 | send_sigio_to_task(p, fown, fd, band, type); |
| 796 | } while_each_pid_task(pid, type, p); |
| 797 | read_unlock(&tasklist_lock); |
| 798 | } |
| 799 | out_unlock_fown: |
| 800 | read_unlock_irqrestore(&fown->lock, flags); |
| 801 | } |
| 802 | |
| 803 | static void send_sigurg_to_task(struct task_struct *p, |
| 804 | struct fown_struct *fown, enum pid_type type) |
| 805 | { |
| 806 | if (sigio_perm(p, fown, SIGURG)) |
| 807 | do_send_sig_info(SIGURG, SEND_SIG_PRIV, p, type); |
| 808 | } |
| 809 | |
| 810 | int send_sigurg(struct fown_struct *fown) |
| 811 | { |
| 812 | struct task_struct *p; |
| 813 | enum pid_type type; |
| 814 | struct pid *pid; |
| 815 | unsigned long flags; |
| 816 | int ret = 0; |
| 817 | |
| 818 | read_lock_irqsave(&fown->lock, flags); |
| 819 | |
| 820 | type = fown->pid_type; |
| 821 | pid = fown->pid; |
| 822 | if (!pid) |
| 823 | goto out_unlock_fown; |
| 824 | |
| 825 | ret = 1; |
| 826 | |
| 827 | if (type <= PIDTYPE_TGID) { |
| 828 | rcu_read_lock(); |
| 829 | p = pid_task(pid, PIDTYPE_PID); |
| 830 | if (p) |
| 831 | send_sigurg_to_task(p, fown, type); |
| 832 | rcu_read_unlock(); |
| 833 | } else { |
| 834 | read_lock(&tasklist_lock); |
| 835 | do_each_pid_task(pid, type, p) { |
| 836 | send_sigurg_to_task(p, fown, type); |
| 837 | } while_each_pid_task(pid, type, p); |
| 838 | read_unlock(&tasklist_lock); |
| 839 | } |
| 840 | out_unlock_fown: |
| 841 | read_unlock_irqrestore(&fown->lock, flags); |
| 842 | return ret; |
| 843 | } |
| 844 | |
| 845 | static DEFINE_SPINLOCK(fasync_lock); |
| 846 | static struct kmem_cache *fasync_cache __read_mostly; |
| 847 | |
| 848 | static void fasync_free_rcu(struct rcu_head *head) |
| 849 | { |
| 850 | kmem_cache_free(fasync_cache, |
| 851 | container_of(head, struct fasync_struct, fa_rcu)); |
| 852 | } |
| 853 | |
| 854 | /* |
| 855 | * Remove a fasync entry. If successfully removed, return |
| 856 | * positive and clear the FASYNC flag. If no entry exists, |
| 857 | * do nothing and return 0. |
| 858 | * |
| 859 | * NOTE! It is very important that the FASYNC flag always |
| 860 | * match the state "is the filp on a fasync list". |
| 861 | * |
| 862 | */ |
| 863 | int fasync_remove_entry(struct file *filp, struct fasync_struct **fapp) |
| 864 | { |
| 865 | struct fasync_struct *fa, **fp; |
| 866 | int result = 0; |
| 867 | |
| 868 | spin_lock(&filp->f_lock); |
| 869 | spin_lock(&fasync_lock); |
| 870 | for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) { |
| 871 | if (fa->fa_file != filp) |
| 872 | continue; |
| 873 | |
| 874 | write_lock_irq(&fa->fa_lock); |
| 875 | fa->fa_file = NULL; |
| 876 | write_unlock_irq(&fa->fa_lock); |
| 877 | |
| 878 | *fp = fa->fa_next; |
| 879 | call_rcu(&fa->fa_rcu, fasync_free_rcu); |
| 880 | filp->f_flags &= ~FASYNC; |
| 881 | result = 1; |
| 882 | break; |
| 883 | } |
| 884 | spin_unlock(&fasync_lock); |
| 885 | spin_unlock(&filp->f_lock); |
| 886 | return result; |
| 887 | } |
| 888 | |
| 889 | struct fasync_struct *fasync_alloc(void) |
| 890 | { |
| 891 | return kmem_cache_alloc(fasync_cache, GFP_KERNEL); |
| 892 | } |
| 893 | |
| 894 | /* |
| 895 | * NOTE! This can be used only for unused fasync entries: |
| 896 | * entries that actually got inserted on the fasync list |
| 897 | * need to be released by rcu - see fasync_remove_entry. |
| 898 | */ |
| 899 | void fasync_free(struct fasync_struct *new) |
| 900 | { |
| 901 | kmem_cache_free(fasync_cache, new); |
| 902 | } |
| 903 | |
| 904 | /* |
| 905 | * Insert a new entry into the fasync list. Return the pointer to the |
| 906 | * old one if we didn't use the new one. |
| 907 | * |
| 908 | * NOTE! It is very important that the FASYNC flag always |
| 909 | * match the state "is the filp on a fasync list". |
| 910 | */ |
| 911 | struct fasync_struct *fasync_insert_entry(int fd, struct file *filp, struct fasync_struct **fapp, struct fasync_struct *new) |
| 912 | { |
| 913 | struct fasync_struct *fa, **fp; |
| 914 | |
| 915 | spin_lock(&filp->f_lock); |
| 916 | spin_lock(&fasync_lock); |
| 917 | for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) { |
| 918 | if (fa->fa_file != filp) |
| 919 | continue; |
| 920 | |
| 921 | write_lock_irq(&fa->fa_lock); |
| 922 | fa->fa_fd = fd; |
| 923 | write_unlock_irq(&fa->fa_lock); |
| 924 | goto out; |
| 925 | } |
| 926 | |
| 927 | rwlock_init(&new->fa_lock); |
| 928 | new->magic = FASYNC_MAGIC; |
| 929 | new->fa_file = filp; |
| 930 | new->fa_fd = fd; |
| 931 | new->fa_next = *fapp; |
| 932 | rcu_assign_pointer(*fapp, new); |
| 933 | filp->f_flags |= FASYNC; |
| 934 | |
| 935 | out: |
| 936 | spin_unlock(&fasync_lock); |
| 937 | spin_unlock(&filp->f_lock); |
| 938 | return fa; |
| 939 | } |
| 940 | |
| 941 | /* |
| 942 | * Add a fasync entry. Return negative on error, positive if |
| 943 | * added, and zero if did nothing but change an existing one. |
| 944 | */ |
| 945 | static int fasync_add_entry(int fd, struct file *filp, struct fasync_struct **fapp) |
| 946 | { |
| 947 | struct fasync_struct *new; |
| 948 | |
| 949 | new = fasync_alloc(); |
| 950 | if (!new) |
| 951 | return -ENOMEM; |
| 952 | |
| 953 | /* |
| 954 | * fasync_insert_entry() returns the old (update) entry if |
| 955 | * it existed. |
| 956 | * |
| 957 | * So free the (unused) new entry and return 0 to let the |
| 958 | * caller know that we didn't add any new fasync entries. |
| 959 | */ |
| 960 | if (fasync_insert_entry(fd, filp, fapp, new)) { |
| 961 | fasync_free(new); |
| 962 | return 0; |
| 963 | } |
| 964 | |
| 965 | return 1; |
| 966 | } |
| 967 | |
| 968 | /* |
| 969 | * fasync_helper() is used by almost all character device drivers |
| 970 | * to set up the fasync queue, and for regular files by the file |
| 971 | * lease code. It returns negative on error, 0 if it did no changes |
| 972 | * and positive if it added/deleted the entry. |
| 973 | */ |
| 974 | int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp) |
| 975 | { |
| 976 | if (!on) |
| 977 | return fasync_remove_entry(filp, fapp); |
| 978 | return fasync_add_entry(fd, filp, fapp); |
| 979 | } |
| 980 | |
| 981 | EXPORT_SYMBOL(fasync_helper); |
| 982 | |
| 983 | /* |
| 984 | * rcu_read_lock() is held |
| 985 | */ |
| 986 | static void kill_fasync_rcu(struct fasync_struct *fa, int sig, int band) |
| 987 | { |
| 988 | while (fa) { |
| 989 | struct fown_struct *fown; |
| 990 | unsigned long flags; |
| 991 | |
| 992 | if (fa->magic != FASYNC_MAGIC) { |
| 993 | printk(KERN_ERR "kill_fasync: bad magic number in " |
| 994 | "fasync_struct!\n"); |
| 995 | return; |
| 996 | } |
| 997 | read_lock_irqsave(&fa->fa_lock, flags); |
| 998 | if (fa->fa_file) { |
| 999 | fown = &fa->fa_file->f_owner; |
| 1000 | /* Don't send SIGURG to processes which have not set a |
| 1001 | queued signum: SIGURG has its own default signalling |
| 1002 | mechanism. */ |
| 1003 | if (!(sig == SIGURG && fown->signum == 0)) |
| 1004 | send_sigio(fown, fa->fa_fd, band); |
| 1005 | } |
| 1006 | read_unlock_irqrestore(&fa->fa_lock, flags); |
| 1007 | fa = rcu_dereference(fa->fa_next); |
| 1008 | } |
| 1009 | } |
| 1010 | |
| 1011 | void kill_fasync(struct fasync_struct **fp, int sig, int band) |
| 1012 | { |
| 1013 | /* First a quick test without locking: usually |
| 1014 | * the list is empty. |
| 1015 | */ |
| 1016 | if (*fp) { |
| 1017 | rcu_read_lock(); |
| 1018 | kill_fasync_rcu(rcu_dereference(*fp), sig, band); |
| 1019 | rcu_read_unlock(); |
| 1020 | } |
| 1021 | } |
| 1022 | EXPORT_SYMBOL(kill_fasync); |
| 1023 | |
| 1024 | static int __init fcntl_init(void) |
| 1025 | { |
| 1026 | /* |
| 1027 | * Please add new bits here to ensure allocation uniqueness. |
| 1028 | * Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY |
| 1029 | * is defined as O_NONBLOCK on some platforms and not on others. |
| 1030 | */ |
| 1031 | BUILD_BUG_ON(21 - 1 /* for O_RDONLY being 0 */ != |
| 1032 | HWEIGHT32( |
| 1033 | (VALID_OPEN_FLAGS & ~(O_NONBLOCK | O_NDELAY)) | |
| 1034 | __FMODE_EXEC | __FMODE_NONOTIFY)); |
| 1035 | |
| 1036 | fasync_cache = kmem_cache_create("fasync_cache", |
| 1037 | sizeof(struct fasync_struct), 0, |
| 1038 | SLAB_PANIC | SLAB_ACCOUNT, NULL); |
| 1039 | return 0; |
| 1040 | } |
| 1041 | |
| 1042 | module_init(fcntl_init) |