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1da177e4 LT |
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> | |
dc009d92 EB |
19 | #include <linux/kernel.h> |
20 | #include <linux/kexec.h> | |
1da177e4 LT |
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> | |
7ed20e1a | 30 | #include <linux/signal.h> |
1da177e4 LT |
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 | } | |
e43379f1 | 233 | if (niceval < task_nice(p) && !can_nice(p, niceval)) { |
1da177e4 LT |
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 | ||
4a00ea1e EB |
364 | void kernel_restart(char *cmd) |
365 | { | |
366 | notifier_call_chain(&reboot_notifier_list, SYS_RESTART, cmd); | |
367 | system_state = SYSTEM_RESTART; | |
368 | device_suspend(PMSG_FREEZE); | |
369 | device_shutdown(); | |
370 | if (!cmd) { | |
371 | printk(KERN_EMERG "Restarting system.\n"); | |
372 | } else { | |
373 | printk(KERN_EMERG "Restarting system with command '%s'.\n", cmd); | |
374 | } | |
375 | printk(".\n"); | |
376 | machine_restart(cmd); | |
377 | } | |
378 | EXPORT_SYMBOL_GPL(kernel_restart); | |
379 | ||
380 | void kernel_kexec(void) | |
381 | { | |
382 | #ifdef CONFIG_KEXEC | |
383 | struct kimage *image; | |
384 | image = xchg(&kexec_image, 0); | |
385 | if (!image) { | |
386 | return; | |
387 | } | |
388 | notifier_call_chain(&reboot_notifier_list, SYS_RESTART, NULL); | |
389 | system_state = SYSTEM_RESTART; | |
390 | device_suspend(PMSG_FREEZE); | |
391 | device_shutdown(); | |
392 | printk(KERN_EMERG "Starting new kernel\n"); | |
393 | machine_shutdown(); | |
394 | machine_kexec(image); | |
395 | #endif | |
396 | } | |
397 | EXPORT_SYMBOL_GPL(kernel_kexec); | |
398 | ||
399 | void kernel_halt(void) | |
400 | { | |
401 | notifier_call_chain(&reboot_notifier_list, SYS_HALT, NULL); | |
402 | system_state = SYSTEM_HALT; | |
403 | device_suspend(PMSG_SUSPEND); | |
404 | device_shutdown(); | |
405 | printk(KERN_EMERG "System halted.\n"); | |
406 | machine_halt(); | |
407 | } | |
408 | EXPORT_SYMBOL_GPL(kernel_halt); | |
409 | ||
410 | void kernel_power_off(void) | |
411 | { | |
412 | notifier_call_chain(&reboot_notifier_list, SYS_POWER_OFF, NULL); | |
413 | system_state = SYSTEM_POWER_OFF; | |
414 | device_suspend(PMSG_SUSPEND); | |
415 | device_shutdown(); | |
416 | printk(KERN_EMERG "Power down.\n"); | |
417 | machine_power_off(); | |
418 | } | |
419 | EXPORT_SYMBOL_GPL(kernel_power_off); | |
1da177e4 LT |
420 | |
421 | /* | |
422 | * Reboot system call: for obvious reasons only root may call it, | |
423 | * and even root needs to set up some magic numbers in the registers | |
424 | * so that some mistake won't make this reboot the whole machine. | |
425 | * You can also set the meaning of the ctrl-alt-del-key here. | |
426 | * | |
427 | * reboot doesn't sync: do that yourself before calling this. | |
428 | */ | |
429 | asmlinkage long sys_reboot(int magic1, int magic2, unsigned int cmd, void __user * arg) | |
430 | { | |
431 | char buffer[256]; | |
432 | ||
433 | /* We only trust the superuser with rebooting the system. */ | |
434 | if (!capable(CAP_SYS_BOOT)) | |
435 | return -EPERM; | |
436 | ||
437 | /* For safety, we require "magic" arguments. */ | |
438 | if (magic1 != LINUX_REBOOT_MAGIC1 || | |
439 | (magic2 != LINUX_REBOOT_MAGIC2 && | |
440 | magic2 != LINUX_REBOOT_MAGIC2A && | |
441 | magic2 != LINUX_REBOOT_MAGIC2B && | |
442 | magic2 != LINUX_REBOOT_MAGIC2C)) | |
443 | return -EINVAL; | |
444 | ||
445 | lock_kernel(); | |
446 | switch (cmd) { | |
447 | case LINUX_REBOOT_CMD_RESTART: | |
4a00ea1e | 448 | kernel_restart(NULL); |
1da177e4 LT |
449 | break; |
450 | ||
451 | case LINUX_REBOOT_CMD_CAD_ON: | |
452 | C_A_D = 1; | |
453 | break; | |
454 | ||
455 | case LINUX_REBOOT_CMD_CAD_OFF: | |
456 | C_A_D = 0; | |
457 | break; | |
458 | ||
459 | case LINUX_REBOOT_CMD_HALT: | |
4a00ea1e | 460 | kernel_halt(); |
1da177e4 LT |
461 | unlock_kernel(); |
462 | do_exit(0); | |
463 | break; | |
464 | ||
465 | case LINUX_REBOOT_CMD_POWER_OFF: | |
4a00ea1e | 466 | kernel_power_off(); |
1da177e4 LT |
467 | unlock_kernel(); |
468 | do_exit(0); | |
469 | break; | |
470 | ||
471 | case LINUX_REBOOT_CMD_RESTART2: | |
472 | if (strncpy_from_user(&buffer[0], arg, sizeof(buffer) - 1) < 0) { | |
473 | unlock_kernel(); | |
474 | return -EFAULT; | |
475 | } | |
476 | buffer[sizeof(buffer) - 1] = '\0'; | |
477 | ||
4a00ea1e | 478 | kernel_restart(buffer); |
1da177e4 LT |
479 | break; |
480 | ||
dc009d92 | 481 | case LINUX_REBOOT_CMD_KEXEC: |
4a00ea1e EB |
482 | kernel_kexec(); |
483 | unlock_kernel(); | |
484 | return -EINVAL; | |
485 | ||
1da177e4 LT |
486 | #ifdef CONFIG_SOFTWARE_SUSPEND |
487 | case LINUX_REBOOT_CMD_SW_SUSPEND: | |
488 | { | |
489 | int ret = software_suspend(); | |
490 | unlock_kernel(); | |
491 | return ret; | |
492 | } | |
493 | #endif | |
494 | ||
495 | default: | |
496 | unlock_kernel(); | |
497 | return -EINVAL; | |
498 | } | |
499 | unlock_kernel(); | |
500 | return 0; | |
501 | } | |
502 | ||
503 | static void deferred_cad(void *dummy) | |
504 | { | |
505 | notifier_call_chain(&reboot_notifier_list, SYS_RESTART, NULL); | |
506 | machine_restart(NULL); | |
507 | } | |
508 | ||
509 | /* | |
510 | * This function gets called by ctrl-alt-del - ie the keyboard interrupt. | |
511 | * As it's called within an interrupt, it may NOT sync: the only choice | |
512 | * is whether to reboot at once, or just ignore the ctrl-alt-del. | |
513 | */ | |
514 | void ctrl_alt_del(void) | |
515 | { | |
516 | static DECLARE_WORK(cad_work, deferred_cad, NULL); | |
517 | ||
518 | if (C_A_D) | |
519 | schedule_work(&cad_work); | |
520 | else | |
521 | kill_proc(cad_pid, SIGINT, 1); | |
522 | } | |
523 | ||
524 | ||
525 | /* | |
526 | * Unprivileged users may change the real gid to the effective gid | |
527 | * or vice versa. (BSD-style) | |
528 | * | |
529 | * If you set the real gid at all, or set the effective gid to a value not | |
530 | * equal to the real gid, then the saved gid is set to the new effective gid. | |
531 | * | |
532 | * This makes it possible for a setgid program to completely drop its | |
533 | * privileges, which is often a useful assertion to make when you are doing | |
534 | * a security audit over a program. | |
535 | * | |
536 | * The general idea is that a program which uses just setregid() will be | |
537 | * 100% compatible with BSD. A program which uses just setgid() will be | |
538 | * 100% compatible with POSIX with saved IDs. | |
539 | * | |
540 | * SMP: There are not races, the GIDs are checked only by filesystem | |
541 | * operations (as far as semantic preservation is concerned). | |
542 | */ | |
543 | asmlinkage long sys_setregid(gid_t rgid, gid_t egid) | |
544 | { | |
545 | int old_rgid = current->gid; | |
546 | int old_egid = current->egid; | |
547 | int new_rgid = old_rgid; | |
548 | int new_egid = old_egid; | |
549 | int retval; | |
550 | ||
551 | retval = security_task_setgid(rgid, egid, (gid_t)-1, LSM_SETID_RE); | |
552 | if (retval) | |
553 | return retval; | |
554 | ||
555 | if (rgid != (gid_t) -1) { | |
556 | if ((old_rgid == rgid) || | |
557 | (current->egid==rgid) || | |
558 | capable(CAP_SETGID)) | |
559 | new_rgid = rgid; | |
560 | else | |
561 | return -EPERM; | |
562 | } | |
563 | if (egid != (gid_t) -1) { | |
564 | if ((old_rgid == egid) || | |
565 | (current->egid == egid) || | |
566 | (current->sgid == egid) || | |
567 | capable(CAP_SETGID)) | |
568 | new_egid = egid; | |
569 | else { | |
570 | return -EPERM; | |
571 | } | |
572 | } | |
573 | if (new_egid != old_egid) | |
574 | { | |
d6e71144 | 575 | current->mm->dumpable = suid_dumpable; |
d59dd462 | 576 | smp_wmb(); |
1da177e4 LT |
577 | } |
578 | if (rgid != (gid_t) -1 || | |
579 | (egid != (gid_t) -1 && egid != old_rgid)) | |
580 | current->sgid = new_egid; | |
581 | current->fsgid = new_egid; | |
582 | current->egid = new_egid; | |
583 | current->gid = new_rgid; | |
584 | key_fsgid_changed(current); | |
585 | return 0; | |
586 | } | |
587 | ||
588 | /* | |
589 | * setgid() is implemented like SysV w/ SAVED_IDS | |
590 | * | |
591 | * SMP: Same implicit races as above. | |
592 | */ | |
593 | asmlinkage long sys_setgid(gid_t gid) | |
594 | { | |
595 | int old_egid = current->egid; | |
596 | int retval; | |
597 | ||
598 | retval = security_task_setgid(gid, (gid_t)-1, (gid_t)-1, LSM_SETID_ID); | |
599 | if (retval) | |
600 | return retval; | |
601 | ||
602 | if (capable(CAP_SETGID)) | |
603 | { | |
604 | if(old_egid != gid) | |
605 | { | |
d6e71144 | 606 | current->mm->dumpable = suid_dumpable; |
d59dd462 | 607 | smp_wmb(); |
1da177e4 LT |
608 | } |
609 | current->gid = current->egid = current->sgid = current->fsgid = gid; | |
610 | } | |
611 | else if ((gid == current->gid) || (gid == current->sgid)) | |
612 | { | |
613 | if(old_egid != gid) | |
614 | { | |
d6e71144 | 615 | current->mm->dumpable = suid_dumpable; |
d59dd462 | 616 | smp_wmb(); |
1da177e4 LT |
617 | } |
618 | current->egid = current->fsgid = gid; | |
619 | } | |
620 | else | |
621 | return -EPERM; | |
622 | ||
623 | key_fsgid_changed(current); | |
624 | return 0; | |
625 | } | |
626 | ||
627 | static int set_user(uid_t new_ruid, int dumpclear) | |
628 | { | |
629 | struct user_struct *new_user; | |
630 | ||
631 | new_user = alloc_uid(new_ruid); | |
632 | if (!new_user) | |
633 | return -EAGAIN; | |
634 | ||
635 | if (atomic_read(&new_user->processes) >= | |
636 | current->signal->rlim[RLIMIT_NPROC].rlim_cur && | |
637 | new_user != &root_user) { | |
638 | free_uid(new_user); | |
639 | return -EAGAIN; | |
640 | } | |
641 | ||
642 | switch_uid(new_user); | |
643 | ||
644 | if(dumpclear) | |
645 | { | |
d6e71144 | 646 | current->mm->dumpable = suid_dumpable; |
d59dd462 | 647 | smp_wmb(); |
1da177e4 LT |
648 | } |
649 | current->uid = new_ruid; | |
650 | return 0; | |
651 | } | |
652 | ||
653 | /* | |
654 | * Unprivileged users may change the real uid to the effective uid | |
655 | * or vice versa. (BSD-style) | |
656 | * | |
657 | * If you set the real uid at all, or set the effective uid to a value not | |
658 | * equal to the real uid, then the saved uid is set to the new effective uid. | |
659 | * | |
660 | * This makes it possible for a setuid program to completely drop its | |
661 | * privileges, which is often a useful assertion to make when you are doing | |
662 | * a security audit over a program. | |
663 | * | |
664 | * The general idea is that a program which uses just setreuid() will be | |
665 | * 100% compatible with BSD. A program which uses just setuid() will be | |
666 | * 100% compatible with POSIX with saved IDs. | |
667 | */ | |
668 | asmlinkage long sys_setreuid(uid_t ruid, uid_t euid) | |
669 | { | |
670 | int old_ruid, old_euid, old_suid, new_ruid, new_euid; | |
671 | int retval; | |
672 | ||
673 | retval = security_task_setuid(ruid, euid, (uid_t)-1, LSM_SETID_RE); | |
674 | if (retval) | |
675 | return retval; | |
676 | ||
677 | new_ruid = old_ruid = current->uid; | |
678 | new_euid = old_euid = current->euid; | |
679 | old_suid = current->suid; | |
680 | ||
681 | if (ruid != (uid_t) -1) { | |
682 | new_ruid = ruid; | |
683 | if ((old_ruid != ruid) && | |
684 | (current->euid != ruid) && | |
685 | !capable(CAP_SETUID)) | |
686 | return -EPERM; | |
687 | } | |
688 | ||
689 | if (euid != (uid_t) -1) { | |
690 | new_euid = euid; | |
691 | if ((old_ruid != euid) && | |
692 | (current->euid != euid) && | |
693 | (current->suid != euid) && | |
694 | !capable(CAP_SETUID)) | |
695 | return -EPERM; | |
696 | } | |
697 | ||
698 | if (new_ruid != old_ruid && set_user(new_ruid, new_euid != old_euid) < 0) | |
699 | return -EAGAIN; | |
700 | ||
701 | if (new_euid != old_euid) | |
702 | { | |
d6e71144 | 703 | current->mm->dumpable = suid_dumpable; |
d59dd462 | 704 | smp_wmb(); |
1da177e4 LT |
705 | } |
706 | current->fsuid = current->euid = new_euid; | |
707 | if (ruid != (uid_t) -1 || | |
708 | (euid != (uid_t) -1 && euid != old_ruid)) | |
709 | current->suid = current->euid; | |
710 | current->fsuid = current->euid; | |
711 | ||
712 | key_fsuid_changed(current); | |
713 | ||
714 | return security_task_post_setuid(old_ruid, old_euid, old_suid, LSM_SETID_RE); | |
715 | } | |
716 | ||
717 | ||
718 | ||
719 | /* | |
720 | * setuid() is implemented like SysV with SAVED_IDS | |
721 | * | |
722 | * Note that SAVED_ID's is deficient in that a setuid root program | |
723 | * like sendmail, for example, cannot set its uid to be a normal | |
724 | * user and then switch back, because if you're root, setuid() sets | |
725 | * the saved uid too. If you don't like this, blame the bright people | |
726 | * in the POSIX committee and/or USG. Note that the BSD-style setreuid() | |
727 | * will allow a root program to temporarily drop privileges and be able to | |
728 | * regain them by swapping the real and effective uid. | |
729 | */ | |
730 | asmlinkage long sys_setuid(uid_t uid) | |
731 | { | |
732 | int old_euid = current->euid; | |
733 | int old_ruid, old_suid, new_ruid, new_suid; | |
734 | int retval; | |
735 | ||
736 | retval = security_task_setuid(uid, (uid_t)-1, (uid_t)-1, LSM_SETID_ID); | |
737 | if (retval) | |
738 | return retval; | |
739 | ||
740 | old_ruid = new_ruid = current->uid; | |
741 | old_suid = current->suid; | |
742 | new_suid = old_suid; | |
743 | ||
744 | if (capable(CAP_SETUID)) { | |
745 | if (uid != old_ruid && set_user(uid, old_euid != uid) < 0) | |
746 | return -EAGAIN; | |
747 | new_suid = uid; | |
748 | } else if ((uid != current->uid) && (uid != new_suid)) | |
749 | return -EPERM; | |
750 | ||
751 | if (old_euid != uid) | |
752 | { | |
d6e71144 | 753 | current->mm->dumpable = suid_dumpable; |
d59dd462 | 754 | smp_wmb(); |
1da177e4 LT |
755 | } |
756 | current->fsuid = current->euid = uid; | |
757 | current->suid = new_suid; | |
758 | ||
759 | key_fsuid_changed(current); | |
760 | ||
761 | return security_task_post_setuid(old_ruid, old_euid, old_suid, LSM_SETID_ID); | |
762 | } | |
763 | ||
764 | ||
765 | /* | |
766 | * This function implements a generic ability to update ruid, euid, | |
767 | * and suid. This allows you to implement the 4.4 compatible seteuid(). | |
768 | */ | |
769 | asmlinkage long sys_setresuid(uid_t ruid, uid_t euid, uid_t suid) | |
770 | { | |
771 | int old_ruid = current->uid; | |
772 | int old_euid = current->euid; | |
773 | int old_suid = current->suid; | |
774 | int retval; | |
775 | ||
776 | retval = security_task_setuid(ruid, euid, suid, LSM_SETID_RES); | |
777 | if (retval) | |
778 | return retval; | |
779 | ||
780 | if (!capable(CAP_SETUID)) { | |
781 | if ((ruid != (uid_t) -1) && (ruid != current->uid) && | |
782 | (ruid != current->euid) && (ruid != current->suid)) | |
783 | return -EPERM; | |
784 | if ((euid != (uid_t) -1) && (euid != current->uid) && | |
785 | (euid != current->euid) && (euid != current->suid)) | |
786 | return -EPERM; | |
787 | if ((suid != (uid_t) -1) && (suid != current->uid) && | |
788 | (suid != current->euid) && (suid != current->suid)) | |
789 | return -EPERM; | |
790 | } | |
791 | if (ruid != (uid_t) -1) { | |
792 | if (ruid != current->uid && set_user(ruid, euid != current->euid) < 0) | |
793 | return -EAGAIN; | |
794 | } | |
795 | if (euid != (uid_t) -1) { | |
796 | if (euid != current->euid) | |
797 | { | |
d6e71144 | 798 | current->mm->dumpable = suid_dumpable; |
d59dd462 | 799 | smp_wmb(); |
1da177e4 LT |
800 | } |
801 | current->euid = euid; | |
802 | } | |
803 | current->fsuid = current->euid; | |
804 | if (suid != (uid_t) -1) | |
805 | current->suid = suid; | |
806 | ||
807 | key_fsuid_changed(current); | |
808 | ||
809 | return security_task_post_setuid(old_ruid, old_euid, old_suid, LSM_SETID_RES); | |
810 | } | |
811 | ||
812 | asmlinkage long sys_getresuid(uid_t __user *ruid, uid_t __user *euid, uid_t __user *suid) | |
813 | { | |
814 | int retval; | |
815 | ||
816 | if (!(retval = put_user(current->uid, ruid)) && | |
817 | !(retval = put_user(current->euid, euid))) | |
818 | retval = put_user(current->suid, suid); | |
819 | ||
820 | return retval; | |
821 | } | |
822 | ||
823 | /* | |
824 | * Same as above, but for rgid, egid, sgid. | |
825 | */ | |
826 | asmlinkage long sys_setresgid(gid_t rgid, gid_t egid, gid_t sgid) | |
827 | { | |
828 | int retval; | |
829 | ||
830 | retval = security_task_setgid(rgid, egid, sgid, LSM_SETID_RES); | |
831 | if (retval) | |
832 | return retval; | |
833 | ||
834 | if (!capable(CAP_SETGID)) { | |
835 | if ((rgid != (gid_t) -1) && (rgid != current->gid) && | |
836 | (rgid != current->egid) && (rgid != current->sgid)) | |
837 | return -EPERM; | |
838 | if ((egid != (gid_t) -1) && (egid != current->gid) && | |
839 | (egid != current->egid) && (egid != current->sgid)) | |
840 | return -EPERM; | |
841 | if ((sgid != (gid_t) -1) && (sgid != current->gid) && | |
842 | (sgid != current->egid) && (sgid != current->sgid)) | |
843 | return -EPERM; | |
844 | } | |
845 | if (egid != (gid_t) -1) { | |
846 | if (egid != current->egid) | |
847 | { | |
d6e71144 | 848 | current->mm->dumpable = suid_dumpable; |
d59dd462 | 849 | smp_wmb(); |
1da177e4 LT |
850 | } |
851 | current->egid = egid; | |
852 | } | |
853 | current->fsgid = current->egid; | |
854 | if (rgid != (gid_t) -1) | |
855 | current->gid = rgid; | |
856 | if (sgid != (gid_t) -1) | |
857 | current->sgid = sgid; | |
858 | ||
859 | key_fsgid_changed(current); | |
860 | return 0; | |
861 | } | |
862 | ||
863 | asmlinkage long sys_getresgid(gid_t __user *rgid, gid_t __user *egid, gid_t __user *sgid) | |
864 | { | |
865 | int retval; | |
866 | ||
867 | if (!(retval = put_user(current->gid, rgid)) && | |
868 | !(retval = put_user(current->egid, egid))) | |
869 | retval = put_user(current->sgid, sgid); | |
870 | ||
871 | return retval; | |
872 | } | |
873 | ||
874 | ||
875 | /* | |
876 | * "setfsuid()" sets the fsuid - the uid used for filesystem checks. This | |
877 | * is used for "access()" and for the NFS daemon (letting nfsd stay at | |
878 | * whatever uid it wants to). It normally shadows "euid", except when | |
879 | * explicitly set by setfsuid() or for access.. | |
880 | */ | |
881 | asmlinkage long sys_setfsuid(uid_t uid) | |
882 | { | |
883 | int old_fsuid; | |
884 | ||
885 | old_fsuid = current->fsuid; | |
886 | if (security_task_setuid(uid, (uid_t)-1, (uid_t)-1, LSM_SETID_FS)) | |
887 | return old_fsuid; | |
888 | ||
889 | if (uid == current->uid || uid == current->euid || | |
890 | uid == current->suid || uid == current->fsuid || | |
891 | capable(CAP_SETUID)) | |
892 | { | |
893 | if (uid != old_fsuid) | |
894 | { | |
d6e71144 | 895 | current->mm->dumpable = suid_dumpable; |
d59dd462 | 896 | smp_wmb(); |
1da177e4 LT |
897 | } |
898 | current->fsuid = uid; | |
899 | } | |
900 | ||
901 | key_fsuid_changed(current); | |
902 | ||
903 | security_task_post_setuid(old_fsuid, (uid_t)-1, (uid_t)-1, LSM_SETID_FS); | |
904 | ||
905 | return old_fsuid; | |
906 | } | |
907 | ||
908 | /* | |
909 |