| 1 | /* |
| 2 | * linux/kernel/sys.c |
| 3 | * |
| 4 | * Copyright (C) 1991, 1992 Linus Torvalds |
| 5 | */ |
| 6 | |
| 7 | #include <linux/config.h> |
| 8 | #include <linux/module.h> |
| 9 | #include <linux/mm.h> |
| 10 | #include <linux/utsname.h> |
| 11 | #include <linux/mman.h> |
| 12 | #include <linux/smp_lock.h> |
| 13 | #include <linux/notifier.h> |
| 14 | #include <linux/reboot.h> |
| 15 | #include <linux/prctl.h> |
| 16 | #include <linux/init.h> |
| 17 | #include <linux/highuid.h> |
| 18 | #include <linux/fs.h> |
| 19 | #include <linux/kernel.h> |
| 20 | #include <linux/kexec.h> |
| 21 | #include <linux/workqueue.h> |
| 22 | #include <linux/device.h> |
| 23 | #include <linux/key.h> |
| 24 | #include <linux/times.h> |
| 25 | #include <linux/posix-timers.h> |
| 26 | #include <linux/security.h> |
| 27 | #include <linux/dcookies.h> |
| 28 | #include <linux/suspend.h> |
| 29 | #include <linux/tty.h> |
| 30 | #include <linux/signal.h> |
| 31 | |
| 32 | #include <linux/compat.h> |
| 33 | #include <linux/syscalls.h> |
| 34 | |
| 35 | #include <asm/uaccess.h> |
| 36 | #include <asm/io.h> |
| 37 | #include <asm/unistd.h> |
| 38 | |
| 39 | #ifndef SET_UNALIGN_CTL |
| 40 | # define SET_UNALIGN_CTL(a,b) (-EINVAL) |
| 41 | #endif |
| 42 | #ifndef GET_UNALIGN_CTL |
| 43 | # define GET_UNALIGN_CTL(a,b) (-EINVAL) |
| 44 | #endif |
| 45 | #ifndef SET_FPEMU_CTL |
| 46 | # define SET_FPEMU_CTL(a,b) (-EINVAL) |
| 47 | #endif |
| 48 | #ifndef GET_FPEMU_CTL |
| 49 | # define GET_FPEMU_CTL(a,b) (-EINVAL) |
| 50 | #endif |
| 51 | #ifndef SET_FPEXC_CTL |
| 52 | # define SET_FPEXC_CTL(a,b) (-EINVAL) |
| 53 | #endif |
| 54 | #ifndef GET_FPEXC_CTL |
| 55 | # define GET_FPEXC_CTL(a,b) (-EINVAL) |
| 56 | #endif |
| 57 | |
| 58 | /* |
| 59 | * this is where the system-wide overflow UID and GID are defined, for |
| 60 | * architectures that now have 32-bit UID/GID but didn't in the past |
| 61 | */ |
| 62 | |
| 63 | int overflowuid = DEFAULT_OVERFLOWUID; |
| 64 | int overflowgid = DEFAULT_OVERFLOWGID; |
| 65 | |
| 66 | #ifdef CONFIG_UID16 |
| 67 | EXPORT_SYMBOL(overflowuid); |
| 68 | EXPORT_SYMBOL(overflowgid); |
| 69 | #endif |
| 70 | |
| 71 | /* |
| 72 | * the same as above, but for filesystems which can only store a 16-bit |
| 73 | * UID and GID. as such, this is needed on all architectures |
| 74 | */ |
| 75 | |
| 76 | int fs_overflowuid = DEFAULT_FS_OVERFLOWUID; |
| 77 | int fs_overflowgid = DEFAULT_FS_OVERFLOWUID; |
| 78 | |
| 79 | EXPORT_SYMBOL(fs_overflowuid); |
| 80 | EXPORT_SYMBOL(fs_overflowgid); |
| 81 | |
| 82 | /* |
| 83 | * this indicates whether you can reboot with ctrl-alt-del: the default is yes |
| 84 | */ |
| 85 | |
| 86 | int C_A_D = 1; |
| 87 | int cad_pid = 1; |
| 88 | |
| 89 | /* |
| 90 | * Notifier list for kernel code which wants to be called |
| 91 | * at shutdown. This is used to stop any idling DMA operations |
| 92 | * and the like. |
| 93 | */ |
| 94 | |
| 95 | static struct notifier_block *reboot_notifier_list; |
| 96 | static DEFINE_RWLOCK(notifier_lock); |
| 97 | |
| 98 | /** |
| 99 | * notifier_chain_register - Add notifier to a notifier chain |
| 100 | * @list: Pointer to root list pointer |
| 101 | * @n: New entry in notifier chain |
| 102 | * |
| 103 | * Adds a notifier to a notifier chain. |
| 104 | * |
| 105 | * Currently always returns zero. |
| 106 | */ |
| 107 | |
| 108 | int notifier_chain_register(struct notifier_block **list, struct notifier_block *n) |
| 109 | { |
| 110 | write_lock(¬ifier_lock); |
| 111 | while(*list) |
| 112 | { |
| 113 | if(n->priority > (*list)->priority) |
| 114 | break; |
| 115 | list= &((*list)->next); |
| 116 | } |
| 117 | n->next = *list; |
| 118 | *list=n; |
| 119 | write_unlock(¬ifier_lock); |
| 120 | return 0; |
| 121 | } |
| 122 | |
| 123 | EXPORT_SYMBOL(notifier_chain_register); |
| 124 | |
| 125 | /** |
| 126 | * notifier_chain_unregister - Remove notifier from a notifier chain |
| 127 | * @nl: Pointer to root list pointer |
| 128 | * @n: New entry in notifier chain |
| 129 | * |
| 130 | * Removes a notifier from a notifier chain. |
| 131 | * |
| 132 | * Returns zero on success, or %-ENOENT on failure. |
| 133 | */ |
| 134 | |
| 135 | int notifier_chain_unregister(struct notifier_block **nl, struct notifier_block *n) |
| 136 | { |
| 137 | write_lock(¬ifier_lock); |
| 138 | while((*nl)!=NULL) |
| 139 | { |
| 140 | if((*nl)==n) |
| 141 | { |
| 142 | *nl=n->next; |
| 143 | write_unlock(¬ifier_lock); |
| 144 | return 0; |
| 145 | } |
| 146 | nl=&((*nl)->next); |
| 147 | } |
| 148 | write_unlock(¬ifier_lock); |
| 149 | return -ENOENT; |
| 150 | } |
| 151 | |
| 152 | EXPORT_SYMBOL(notifier_chain_unregister); |
| 153 | |
| 154 | /** |
| 155 | * notifier_call_chain - Call functions in a notifier chain |
| 156 | * @n: Pointer to root pointer of notifier chain |
| 157 | * @val: Value passed unmodified to notifier function |
| 158 | * @v: Pointer passed unmodified to notifier function |
| 159 | * |
| 160 | * Calls each function in a notifier chain in turn. |
| 161 | * |
| 162 | * If the return value of the notifier can be and'd |
| 163 | * with %NOTIFY_STOP_MASK, then notifier_call_chain |
| 164 | * will return immediately, with the return value of |
| 165 | * the notifier function which halted execution. |
| 166 | * Otherwise, the return value is the return value |
| 167 | * of the last notifier function called. |
| 168 | */ |
| 169 | |
| 170 | int notifier_call_chain(struct notifier_block **n, unsigned long val, void *v) |
| 171 | { |
| 172 | int ret=NOTIFY_DONE; |
| 173 | struct notifier_block *nb = *n; |
| 174 | |
| 175 | while(nb) |
| 176 | { |
| 177 | ret=nb->notifier_call(nb,val,v); |
| 178 | if(ret&NOTIFY_STOP_MASK) |
| 179 | { |
| 180 | return ret; |
| 181 | } |
| 182 | nb=nb->next; |
| 183 | } |
| 184 | return ret; |
| 185 | } |
| 186 | |
| 187 | EXPORT_SYMBOL(notifier_call_chain); |
| 188 | |
| 189 | /** |
| 190 | * register_reboot_notifier - Register function to be called at reboot time |
| 191 | * @nb: Info about notifier function to be called |
| 192 | * |
| 193 | * Registers a function with the list of functions |
| 194 | * to be called at reboot time. |
| 195 | * |
| 196 | * Currently always returns zero, as notifier_chain_register |
| 197 | * always returns zero. |
| 198 | */ |
| 199 | |
| 200 | int register_reboot_notifier(struct notifier_block * nb) |
| 201 | { |
| 202 | return notifier_chain_register(&reboot_notifier_list, nb); |
| 203 | } |
| 204 | |
| 205 | EXPORT_SYMBOL(register_reboot_notifier); |
| 206 | |
| 207 | /** |
| 208 | * unregister_reboot_notifier - Unregister previously registered reboot notifier |
| 209 | * @nb: Hook to be unregistered |
| 210 | * |
| 211 | * Unregisters a previously registered reboot |
| 212 | * notifier function. |
| 213 | * |
| 214 | * Returns zero on success, or %-ENOENT on failure. |
| 215 | */ |
| 216 | |
| 217 | int unregister_reboot_notifier(struct notifier_block * nb) |
| 218 | { |
| 219 | return notifier_chain_unregister(&reboot_notifier_list, nb); |
| 220 | } |
| 221 | |
| 222 | EXPORT_SYMBOL(unregister_reboot_notifier); |
| 223 | |
| 224 | static int set_one_prio(struct task_struct *p, int niceval, int error) |
| 225 | { |
| 226 | int no_nice; |
| 227 | |
| 228 | if (p->uid != current->euid && |
| 229 | p->euid != current->euid && !capable(CAP_SYS_NICE)) { |
| 230 | error = -EPERM; |
| 231 | goto out; |
| 232 | } |
| 233 | if (niceval < task_nice(p) && !can_nice(p, niceval)) { |
| 234 | error = -EACCES; |
| 235 | goto out; |
| 236 | } |
| 237 | no_nice = security_task_setnice(p, niceval); |
| 238 | if (no_nice) { |
| 239 | error = no_nice; |
| 240 | goto out; |
| 241 | } |
| 242 | if (error == -ESRCH) |
| 243 | error = 0; |
| 244 | set_user_nice(p, niceval); |
| 245 | out: |
| 246 | return error; |
| 247 | } |
| 248 | |
| 249 | asmlinkage long sys_setpriority(int which, int who, int niceval) |
| 250 | { |
| 251 | struct task_struct *g, *p; |
| 252 | struct user_struct *user; |
| 253 | int error = -EINVAL; |
| 254 | |
| 255 | if (which > 2 || which < 0) |
| 256 | goto out; |
| 257 | |
| 258 | /* normalize: avoid signed division (rounding problems) */ |
| 259 | error = -ESRCH; |
| 260 | if (niceval < -20) |
| 261 | niceval = -20; |
| 262 | if (niceval > 19) |
| 263 | niceval = 19; |
| 264 | |
| 265 | read_lock(&tasklist_lock); |
| 266 | switch (which) { |
| 267 | case PRIO_PROCESS: |
| 268 | if (!who) |
| 269 | who = current->pid; |
| 270 | p = find_task_by_pid(who); |
| 271 | if (p) |
| 272 | error = set_one_prio(p, niceval, error); |
| 273 | break; |
| 274 | case PRIO_PGRP: |
| 275 | if (!who) |
| 276 | who = process_group(current); |
| 277 | do_each_task_pid(who, PIDTYPE_PGID, p) { |
| 278 | error = set_one_prio(p, niceval, error); |
| 279 | } while_each_task_pid(who, PIDTYPE_PGID, p); |
| 280 | break; |
| 281 | case PRIO_USER: |
| 282 | user = current->user; |
| 283 | if (!who) |
| 284 | who = current->uid; |
| 285 | else |
| 286 | if ((who != current->uid) && !(user = find_user(who))) |
| 287 | goto out_unlock; /* No processes for this user */ |
| 288 | |
| 289 | do_each_thread(g, p) |
| 290 | if (p->uid == who) |
| 291 | error = set_one_prio(p, niceval, error); |
| 292 | while_each_thread(g, p); |
| 293 | if (who != current->uid) |
| 294 | free_uid(user); /* For find_user() */ |
| 295 | break; |
| 296 | } |
| 297 | out_unlock: |
| 298 | read_unlock(&tasklist_lock); |
| 299 | out: |
| 300 | return error; |
| 301 | } |
| 302 | |
| 303 | /* |
| 304 | * Ugh. To avoid negative return values, "getpriority()" will |
| 305 | * not return the normal nice-value, but a negated value that |
| 306 | * has been offset by 20 (ie it returns 40..1 instead of -20..19) |
| 307 | * to stay compatible. |
| 308 | */ |
| 309 | asmlinkage long sys_getpriority(int which, int who) |
| 310 | { |
| 311 | struct task_struct *g, *p; |
| 312 | struct user_struct *user; |
| 313 | long niceval, retval = -ESRCH; |
| 314 | |
| 315 | if (which > 2 || which < 0) |
| 316 | return -EINVAL; |
| 317 | |
| 318 | read_lock(&tasklist_lock); |
| 319 | switch (which) { |
| 320 | case PRIO_PROCESS: |
| 321 | if (!who) |
| 322 | who = current->pid; |
| 323 | p = find_task_by_pid(who); |
| 324 | if (p) { |
| 325 | niceval = 20 - task_nice(p); |
| 326 | if (niceval > retval) |
| 327 | retval = niceval; |
| 328 | } |
| 329 | break; |
| 330 | case PRIO_PGRP: |
| 331 | if (!who) |
| 332 | who = process_group(current); |
| 333 | do_each_task_pid(who, PIDTYPE_PGID, p) { |
| 334 | niceval = 20 - task_nice(p); |
| 335 | if (niceval > retval) |
| 336 | retval = niceval; |
| 337 | } while_each_task_pid(who, PIDTYPE_PGID, p); |
| 338 | break; |
| 339 | case PRIO_USER: |
| 340 | user = current->user; |
| 341 | if (!who) |
| 342 | who = current->uid; |
| 343 | else |
| 344 | if ((who != current->uid) && !(user = find_user(who))) |
| 345 | goto out_unlock; /* No processes for this user */ |
| 346 | |
| 347 | do_each_thread(g, p) |
| 348 | if (p->uid == who) { |
| 349 | niceval = 20 - task_nice(p); |
| 350 | if (niceval > retval) |
| 351 | retval = niceval; |
| 352 | } |
| 353 | while_each_thread(g, p); |
| 354 | if (who != current->uid) |
| 355 | free_uid(user); /* for find_user() */ |
| 356 | break; |
| 357 | } |
| 358 | out_unlock: |
| 359 | read_unlock(&tasklist_lock); |
| 360 | |
| 361 | return retval; |
| 362 | } |
| 363 | |
| 364 | void emergency_restart(void) |
| 365 | { |
| 366 | machine_emergency_restart(); |
| 367 | } |
| 368 | EXPORT_SYMBOL_GPL(emergency_restart); |
| 369 | |
| 370 | void kernel_restart(char *cmd) |
| 371 | { |
| 372 | notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd); |
| 373 | system_state = SYSTEM_RESTART; |
| 374 | device_shutdown(); |
| 375 | if (!cmd) { |
| 376 | printk(KERN_EMERG "Restarting system.\n"); |
| 377 | } else { |
| 378 | printk(KERN_EMERG "Restarting system with command '%s'.\n", cmd); |
| 379 | } |
| 380 | printk(".\n"); |
| 381 | machine_restart(cmd); |
| 382 | } |
| 383 | EXPORT_SYMBOL_GPL(kernel_restart); |
| 384 | |
| 385 | void kernel_kexec(void) |
| 386 | { |
| 387 | #ifdef CONFIG_KEXEC |
| 388 | struct kimage *image; |
| 389 | image = xchg(&kexec_image, 0); |
| 390 | if (!image) { |
| 391 | return; |
| 392 | } |
| 393 | notifier_call_chain(&reboot_notifier_list, SYS_RESTART, NULL); |
| 394 | system_state = SYSTEM_RESTART; |
| 395 | device_shutdown(); |
| 396 | printk(KERN_EMERG "Starting new kernel\n"); |
| 397 | machine_shutdown(); |
| 398 | machine_kexec(image); |
| 399 | #endif |
| 400 | } |
| 401 | EXPORT_SYMBOL_GPL(kernel_kexec); |
| 402 | |
| 403 | void kernel_halt(void) |
| 404 | { |
| 405 | notifier_call_chain(&reboot_notifier_list, SYS_HALT, NULL); |
| 406 | system_state = SYSTEM_HALT; |
| 407 | device_suspend(PMSG_SUSPEND); |
| 408 | device_shutdown(); |
| 409 | printk(KERN_EMERG "System halted.\n"); |
| 410 | machine_halt(); |
| 411 | } |
| 412 | EXPORT_SYMBOL_GPL(kernel_halt); |
| 413 | |
| 414 | void kernel_power_off(void) |
| 415 | { |
| 416 | notifier_call_chain(&reboot_notifier_list, SYS_POWER_OFF, NULL); |
| 417 | system_state = SYSTEM_POWER_OFF; |
| 418 | device_suspend(PMSG_SUSPEND); |
| 419 | device_shutdown(); |
| 420 | printk(KERN_EMERG "Power down.\n"); |
| 421 | machine_power_off(); |
| 422 | } |
| 423 | EXPORT_SYMBOL_GPL(kernel_power_off); |
| 424 | |
| 425 | /* |
| 426 | * Reboot system call: for obvious reasons only root may call it, |
| 427 | * and even root needs to set up some magic numbers in the registers |
| 428 | * so that some mistake won't make this reboot the whole machine. |
| 429 | * You can also set the meaning of the ctrl-alt-del-key here. |
| 430 | * |
| 431 | * reboot doesn't sync: do that yourself before calling this. |
| 432 | */ |
| 433 | asmlinkage long sys_reboot(int magic1, int magic2, unsigned int cmd, void __user * arg) |
| 434 | { |
| 435 | char buffer[256]; |
| 436 | |
| 437 | /* We only trust the superuser with rebooting the system. */ |
| 438 | if (!capable(CAP_SYS_BOOT)) |
| 439 | return -EPERM; |
| 440 | |
| 441 | /* For safety, we require "magic" arguments. */ |
| 442 | if (magic1 != LINUX_REBOOT_MAGIC1 || |
| 443 | (magic2 != LINUX_REBOOT_MAGIC2 && |
| 444 | magic2 != LINUX_REBOOT_MAGIC2A && |
| 445 | magic2 != LINUX_REBOOT_MAGIC2B && |
| 446 | magic2 != LINUX_REBOOT_MAGIC2C)) |
| 447 | return -EINVAL; |
| 448 | |
| 449 | lock_kernel(); |
| 450 | switch (cmd) { |
| 451 | case LINUX_REBOOT_CMD_RESTART: |
| 452 | kernel_restart(NULL); |
| 453 | break; |
| 454 | |
| 455 | case LINUX_REBOOT_CMD_CAD_ON: |
| 456 | C_A_D = 1; |
| 457 | break; |
| 458 | |
| 459 | case LINUX_REBOOT_CMD_CAD_OFF: |
| 460 | C_A_D = 0; |
| 461 | break; |
| 462 | |
| 463 | case LINUX_REBOOT_CMD_HALT: |
| 464 | kernel_halt(); |
| 465 | unlock_kernel(); |
| 466 | do_exit(0); |
| 467 | break; |
| 468 | |
| 469 | case LINUX_REBOOT_CMD_POWER_OFF: |
| 470 | kernel_power_off(); |
| 471 | unlock_kernel(); |
| 472 | do_exit(0); |
| 473 | break; |
| 474 | |
| 475 | case LINUX_REBOOT_CMD_RESTART2: |
| 476 | if (strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1) < 0) { |
| 477 | unlock_kernel(); |
| 478 | return -EFAULT; |
| 479 | } |
| 480 | buffer[sizeof(buffer) - 1] = '\0'; |
| 481 | |
| 482 | kernel_restart(buffer); |
| 483 | break; |
| 484 | |
| 485 | case LINUX_REBOOT_CMD_KEXEC: |
| 486 | kernel_kexec(); |
| 487 | unlock_kernel(); |
| 488 | return -EINVAL; |
| 489 | |
| 490 | #ifdef CONFIG_SOFTWARE_SUSPEND |
| 491 | case LINUX_REBOOT_CMD_SW_SUSPEND: |
| 492 | { |
| 493 | int ret = software_suspend(); |
| 494 | unlock_kernel(); |
| 495 | return ret; |
| 496 | } |
| 497 | #endif |
| 498 | |
| 499 | default: |
| 500 | unlock_kernel(); |
| 501 | return -EINVAL; |
| 502 | } |
| 503 | unlock_kernel(); |
| 504 | return 0; |
| 505 | } |
| 506 | |
| 507 | static void deferred_cad(void *dummy) |
| 508 | { |
| 509 | kernel_restart(NULL); |
| 510 | } |
| 511 | |
| 512 | /* |
| 513 | * This function gets called by ctrl-alt-del - ie the keyboard interrupt. |
| 514 | * As it's called within an interrupt, it may NOT sync: the only choice |
| 515 | * is whether to reboot at once, or just ignore the ctrl-alt-del. |
| 516 | */ |
| 517 | void ctrl_alt_del(void) |
| 518 | { |
| 519 | static DECLARE_WORK(cad_work, deferred_cad, NULL); |
| 520 | |
| 521 | if (C_A_D) |
| 522 | schedule_work(&cad_work); |
| 523 | else |
| 524 | kill_proc(cad_pid, SIGINT, 1); |
| 525 | } |
| 526 | |
| 527 | |
| 528 | /* |
| 529 | * Unprivileged users may change the real gid to the effective gid |
| 530 | * or vice versa. (BSD-style) |
| 531 | * |
| 532 | * If you set the real gid at all, or set the effective gid to a value not |
| 533 | * equal to the real gid, then the saved gid is set to the new effective gid. |
| 534 | * |
| 535 | * This makes it possible for a setgid program to completely drop its |
| 536 | * privileges, which is often a useful assertion to make when you are doing |
| 537 | * a security audit over a program. |
| 538 | * |
| 539 | * The general idea is that a program which uses just setregid() will be |
| 540 | * 100% compatible with BSD. A program which uses just setgid() will be |
| 541 | * 100% compatible with POSIX with saved IDs. |
| 542 | * |
| 543 | * SMP: There are not races, the GIDs are checked only by filesystem |
| 544 | * operations (as far as semantic preservation is concerned). |
| 545 | */ |
| 546 | asmlinkage long sys_setregid(gid_t rgid, gid_t egid) |
| 547 | { |
| 548 | int old_rgid = current->gid; |
| 549 | int old_egid = current->egid; |
| 550 | int new_rgid = old_rgid; |
| 551 | int new_egid = old_egid; |
| 552 | int retval; |
| 553 | |
| 554 | retval = security_task_setgid(rgid, egid, (gid_t)-1, LSM_SETID_RE); |
| 555 | if (retval) |
| 556 | return retval; |
| 557 | |
| 558 | if (rgid != (gid_t) -1) { |
| 559 | if ((old_rgid == rgid) || |
| 560 | (current->egid==rgid) || |
| 561 | capable(CAP_SETGID)) |
| 562 | new_rgid = rgid; |
| 563 | else |
| 564 | return -EPERM; |
| 565 | } |
| 566 | if (egid != (gid_t) -1) { |
| 567 | if ((old_rgid == egid) || |
| 568 | (current->egid == egid) || |
| 569 | (current->sgid == egid) || |
| 570 | capable(CAP_SETGID)) |
| 571 | new_egid = egid; |
| 572 | else { |
| 573 | return -EPERM; |
| 574 | } |
| 575 | } |
| 576 | if (new_egid != old_egid) |
| 577 | { |
| 578 | current->mm->dumpable = suid_dumpable; |
| 579 | smp_wmb(); |
| 580 | } |
| 581 | if (rgid != (gid_t) -1 || |
| 582 | (egid != (gid_t) -1 && egid != old_rgid)) |
| 583 | current->sgid = new_egid; |
| 584 | current->fsgid = new_egid; |
| 585 | current->egid = new_egid; |
| 586 | current->gid = new_rgid; |
| 587 | key_fsgid_changed(current); |
| 588 | return 0; |
| 589 | } |
| 590 | |
| 591 | /* |
| 592 | * setgid() is implemented like SysV w/ SAVED_IDS |
| 593 | * |
| 594 | * SMP: Same implicit races as above. |
| 595 | */ |
| 596 | asmlinkage long sys_setgid(gid_t gid) |
| 597 | { |
| 598 | int old_egid = current->egid; |
| 599 | int retval; |
| 600 | |
| 601 | retval = security_task_setgid(gid, (gid_t)-1, (gid_t)-1, LSM_SETID_ID); |
| 602 | if (retval) |
| 603 | return retval; |
| 604 | |
| 605 | if (capable(CAP_SETGID)) |
| 606 | { |
| 607 | if(old_egid != gid) |
| 608 | { |
| 609 | current->mm->dumpable = suid_dumpable; |
| 610 | smp_wmb(); |
| 611 | } |
| 612 | current->gid = current->egid = current->sgid = current->fsgid = gid; |
| 613 | } |
| 614 | else if ((gid == current->gid) || (gid == current->sgid)) |
| 615 | { |
| 616 | if(old_egid != gid) |
| 617 | { |
| 618 | current->mm->dumpable = suid_dumpable; |
| 619 | smp_wmb(); |
| 620 | } |
| 621 | current->egid = current->fsgid = gid; |
| 622 | } |
| 623 | else |
| 624 | return -EPERM; |
| 625 | |
| 626 | key_fsgid_changed(current); |
| 627 | return 0; |
| 628 | } |
| 629 | |
| 630 | static int set_user(uid_t new_ruid, int dumpclear) |
| 631 | { |
| 632 | struct user_struct *new_user; |
| 633 | |
| 634 | new_user = alloc_uid(new_ruid); |
| 635 | if (!new_user) |
| 636 | return -EAGAIN; |
| 637 | |
| 638 | if (atomic_read(&new_user->processes) >= |
| 639 | current->signal->rlim[RLIMIT_NPROC].rlim_cur && |
| 640 | new_user != &root_user) { |
| 641 | free_uid(new_user); |
| 642 | return -EAGAIN; |
| 643 | } |
| 644 | |
| 645 | switch_uid(new_user); |
| 646 | |
| 647 | if(dumpclear) |
| 648 | { |
| 649 | current->mm->dumpable = suid_dumpable; |
| 650 | smp_wmb(); |
| 651 | } |
| 652 | current->uid = new_ruid; |
| 653 | return 0; |
| 654 | } |
| 655 | |
| 656 | /* |
| 657 | * Unprivileged users may change the real uid to the effective uid |
| 658 | * or vice versa. (BSD-style) |
| 659 | * |
| 660 | * If you set the real uid at all, or set the effective uid to a value not |
| 661 | * equal to the real uid, then the saved uid is set to the new effective uid. |
| 662 | * |
| 663 | * This makes it possible for a setuid program to completely drop its |
| 664 | * privileges, which is often a useful assertion to make when you are doing |
| 665 | * a security audit over a program. |
| 666 | * |
| 667 | * The general idea is that a program which uses just setreuid() will be |
| 668 | * 100% compatible with BSD. A program which uses just setuid() will be |
| 669 | * 100% compatible with POSIX with saved IDs. |
| 670 | */ |
| 671 | asmlinkage long sys_setreuid(uid_t ruid, uid_t euid) |
| 672 | { |
| 673 | int old_ruid, old_euid, old_suid, new_ruid, new_euid; |
| 674 | int retval; |
| 675 | |
| 676 | retval = security_task_setuid(ruid, euid, (uid_t)-1, LSM_SETID_RE); |
| 677 | if (retval) |
| 678 | return retval; |
| 679 | |
| 680 | new_ruid = old_ruid = current->uid; |
| 681 | new_euid = old_euid = current->euid; |
| 682 | old_suid = current->suid; |
| 683 | |
| 684 | if (ruid != (uid_t) -1) { |
| 685 | new_ruid = ruid; |
| 686 | if ((old_ruid != ruid) && |
| 687 | (current->euid != ruid) && |
| 688 | !capable(CAP_SETUID)) |
| 689 | return -EPERM; |
| 690 | } |
| 691 | |
| 692 | if (euid != (uid_t) -1) { |
| 693 | new_euid = euid; |
| 694 | if ((old_ruid != euid) && |
| 695 | (current->euid != euid) && |
| 696 | (current->suid != euid) && |
| 697 | !capable(CAP_SETUID)) |
| 698 | return -EPERM; |
| 699 | } |
| 700 | |
| 701 | if (new_ruid != old_ruid && set_user(new_ruid, new_euid != old_euid) < 0) |
| 702 | return -EAGAIN; |
| 703 | |
| 704 | if (new_euid != old_euid) |
| 705 | { |
| 706 | current->mm->dumpable = suid_dumpable; |
| 707 | smp_wmb(); |
| 708 | } |
| 709 | current->fsuid = current->euid = new_euid; |
| 710 | if (ruid != (uid_t) -1 || |
| 711 | (euid != (uid_t) -1 && euid != old_ruid)) |
| 712 | current->suid = current->euid; |
| 713 | current->fsuid = current->euid; |
| 714 | |
| 715 | key_fsuid_changed(current); |
| 716 | |
| 717 | return security_task_post_setuid(old_ruid, old_euid, old_suid, LSM_SETID_RE); |
| 718 | } |
| 719 | |
| 720 | |
| 721 | |
| 722 | /* |
| 723 | * setuid() is implemented like SysV with SAVED_IDS |
| 724 | * |
| 725 | * Note that SAVED_ID's is deficient in that a setuid root program |
| 726 | * like sendmail, for example, cannot set its uid to be a normal |
| 727 | * user and then switch back, because if you're root, setuid() sets |
| 728 | * the saved uid too. If you don't like this, blame the bright people |
| 729 | * in the POSIX committee and/or USG. Note that the BSD-style setreuid() |
| 730 | * will allow a root program to temporarily drop privileges and be able to |
| 731 | * regain them by swapping the real and effective uid. |
| 732 | */ |
| 733 | asmlinkage long sys_setuid(uid_t uid) |
| 734 | { |
| 735 | int old_euid = current->euid; |
| 736 | int old_ruid, old_suid, new_ruid, new_suid; |
| 737 | int retval; |
| 738 | |
| 739 | retval = security_task_setuid(uid, (uid_t)-1, (uid_t)-1, LSM_SETID_ID); |
| 740 | if (retval) |
| 741 | return retval; |
| 742 | |
| 743 | old_ruid = new_ruid = current->uid; |
| 744 | old_suid = current->suid; |
| 745 | new_suid = old_suid; |
| 746 | |
| 747 | if (capable(CAP_SETUID)) { |
| 748 | if (uid != old_ruid && set_user(uid, old_euid != uid) < 0) |
| 749 | return -EAGAIN; |
| 750 | new_suid = uid; |
| 751 | } else if ((uid != current->uid) && (uid != new_suid)) |
| 752 | return -EPERM; |
| 753 | |
| 754 | if (old_euid != uid) |
| 755 | { |
| 756 | current->mm->dumpable = suid_dumpable; |
| 757 | smp_wmb(); |
| 758 | } |
| 759 | current->fsuid = current->euid = uid; |
| 760 | current->suid = new_suid; |
| 761 | |
| 762 | key_fsuid_changed(current); |
| 763 | |
| 764 | return security_task_post_setuid(old_ruid, old_euid, old_suid, LSM_SETID_ID); |
| 765 | } |
| 766 | |
| 767 | |
| 768 | /* |
| 769 | * This function implements a generic ability to update ruid, euid, |
| 770 | * and suid. This allows you to implement the 4.4 compatible seteuid(). |
| 771 | */ |
| 772 | asmlinkage long sys_setresuid(uid_t ruid, uid_t euid, uid_t suid) |
| 773 | { |
| 774 | int old_ruid = current->uid; |
| 775 | int old_euid = current->euid; |
| 776 | int old_suid = current->suid; |
| 777 | int retval; |
| 778 | |
| 779 | retval = security_task_setuid(ruid, euid, suid, LSM_SETID_RES); |
| 780 | if (retval) |
| 781 | return retval; |
| 782 | |
| 783 | if (!capable(CAP_SETUID)) { |
| 784 | if ((ruid != (uid_t) -1) && (ruid != current->uid) && |
| 785 | (ruid != current->euid) && (ruid != current->suid)) |
| 786 | return -EPERM; |
| 787 | if ((euid != (uid_t) -1) && (euid != current->uid) && |
| 788 | (euid != current->euid) && (euid != current->suid)) |
| 789 | return -EPERM; |
| 790 | if ((suid != (uid_t) -1) && (suid != current->uid) && |
| 791 | (suid != current->euid) && (suid != current->suid)) |
| 792 | return -EPERM; |
| 793 | } |
| 794 | if (ruid != (uid_t) -1) { |
| 795 | if (ruid != current->uid && set_user(ruid, euid != current->euid) < 0) |
| 796 | return -EAGAIN; |
| 797 | } |
| 798 | if (euid != (uid_t) -1) { |
| 799 | if (euid != current->euid) |
| 800 | { |
| 801 | current->mm->dumpable = suid_dumpable; |
| 802 | smp_wmb(); |
| 803 | } |
| 804 | current->euid = euid; |
| 805 | } |
| 806 | current->fsuid = current->euid; |
| 807 | if (suid != (uid_t) -1) |
| 808 | current->suid = suid; |
| 809 | |
| 810 | key_fsuid_changed(current); |
| 811 | |
| 812 | return security_task_post_setuid(old_ruid, old_euid, old_suid, LSM_SETID_RES); |
| 813 | } |
| 814 | |
| 815 | asmlinkage long sys_getresuid(uid_t __user *ruid, uid_t __user *euid, uid_t __user *suid) |
| 816 | { |
| 817 | int retval; |
| 818 | |
| 819 | if (!(retval = put_user(current->uid, ruid)) && |
| 820 | !(retval = put_user(current->euid, euid))) |
| 821 | retval = put_user(current->suid, suid); |
| 822 | |
| 823 | return retval; |
| 824 | } |
| 825 | |
| 826 | /* |
| 827 | * Same as above, but for rgid, egid, sgid. |
| 828 | */ |
| 829 | asmlinkage long sys_setresgid(gid_t rgid, gid_t egid, gid_t sgid) |
| 830 | { |
| 831 | int retval; |
| 832 | |
| 833 | retval = security_task_setgid(rgid, egid, sgid, LSM_SETID_RES); |
| 834 | if (retval) |
| 835 | return retval; |
| 836 | |
| 837 | if (!capable(CAP_SETGID)) { |
| 838 | if ((rgid != (gid_t) -1) && (rgid != current->gid) && |
| 839 | (rgid != current->egid) && (rgid != current->sgid)) |
| 840 | return -EPERM; |
| 841 | if ((egid != (gid_t) -1) && (egid != current->gid) && |
| 842 | (egid != current->egid) && (egid != current->sgid)) |
| 843 | return -EPERM; |
| 844 | if ((sgid != (gid_t) -1) && (sgid != current->gid) && |
| 845 | (sgid != current->egid) && (sgid != current->sgid)) |
| 846 | return -EPERM; |
| 847 | } |
| 848 | if (egid != (gid_t) -1) { |
| 849 | if (egid != current->egid) |
| 850 | { |
| 851 | current->mm->dumpable = suid_dumpable; |
| 852 | smp_wmb(); |
| 853 | } |
| 854 | current->egid = egid; |
| 855 | } |
| 856 | current->fsgid = current->egid; |
| 857 | if (rgid != (gid_t) -1) |
| 858 | current->gid = rgid; |
| 859 | if (sgid != (gid_t) -1) |
| 860 | current->sgid = sgid; |
| 861 | |
| 862 | key_fsgid_changed(current); |
| 863 | return 0; |
| 864 | } |
| 865 | |
| 866 | asmlinkage long sys_getresgid(gid_t __user *rgid, gid_t __user *egid, gid_t __user *sgid) |
| 867 | { |
| 868 | int retval; |
| 869 | |
| 870 | if (!(retval = put_user(current->gid, rgid)) && |
| 871 | !(retval = put_user(current->egid, egid))) |
| 872 | retval = put_user(current->sgid, sgid); |
| 873 | |
| 874 | return retval; |
| 875 | } |
| 876 | |
| 877 | |
| 878 | /* |
| 879 | * "setfsuid()" sets the fsuid - the uid used for filesystem checks. This |
| 880 | * is used for "access()" and for the NFS daemon (letting nfsd stay at |
| 881 | * whatever uid it wants to). It normally shadows "euid", except when |
| 882 | * explicitly set by setfsuid() or for access.. |
| 883 | */ |
| 884 | asmlinkage long sys_setfsuid(uid_t uid) |
| 885 | { |
| 886 | int old_fsuid; |
| 887 | |
| 888 | old_fsuid = current->fsuid; |
| 889 | if (security_task_setuid(uid, (uid_t)-1, (uid_t)-1, LSM_SETID_FS)) |
| 890 | return old_fsuid; |
| 891 | |
| 892 | if (uid == current->uid || uid == current->euid || |
| 893 | uid == current->suid || uid == current->fsuid || |
| 894 | capable(CAP_SETUID)) |
| 895 | { |
| 896 | if (uid != old_fsuid) |
| 897 | { |
| 898 | current->mm->dumpable = suid_dumpable; |
| 899 | smp_wmb(); |
| 900 | } |
| 901 | current->fsuid = uid; |
| 902 | } |
| 903 | |
| 904 | key_fsuid_changed(current); |
| 905 | |
| 906 | security_task_post_setuid(old_fsuid, (uid_t)-1, (uid_t)-1, LSM_SETID_FS); |
| 907 | |
| 908 | return old_fsuid; |
| 909 | } |
| 910 | |
| 911 | /* |
| 912 |