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Linux/security/keys/keyctl.c

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  1 /* Userspace key control operations
  2  *
  3  * Copyright (C) 2004-5 Red Hat, Inc. All Rights Reserved.
  4  * Written by David Howells (dhowells@redhat.com)
  5  *
  6  * This program is free software; you can redistribute it and/or
  7  * modify it under the terms of the GNU General Public License
  8  * as published by the Free Software Foundation; either version
  9  * 2 of the License, or (at your option) any later version.
 10  */
 11 
 12 #include <linux/module.h>
 13 #include <linux/init.h>
 14 #include <linux/sched.h>
 15 #include <linux/slab.h>
 16 #include <linux/syscalls.h>
 17 #include <linux/key.h>
 18 #include <linux/keyctl.h>
 19 #include <linux/fs.h>
 20 #include <linux/capability.h>
 21 #include <linux/string.h>
 22 #include <linux/err.h>
 23 #include <linux/vmalloc.h>
 24 #include <linux/security.h>
 25 #include <linux/uio.h>
 26 #include <asm/uaccess.h>
 27 #include "internal.h"
 28 
 29 static int key_get_type_from_user(char *type,
 30                                   const char __user *_type,
 31                                   unsigned len)
 32 {
 33         int ret;
 34 
 35         ret = strncpy_from_user(type, _type, len);
 36         if (ret < 0)
 37                 return ret;
 38         if (ret == 0 || ret >= len)
 39                 return -EINVAL;
 40         if (type[0] == '.')
 41                 return -EPERM;
 42         type[len - 1] = '\0';
 43         return 0;
 44 }
 45 
 46 /*
 47  * Extract the description of a new key from userspace and either add it as a
 48  * new key to the specified keyring or update a matching key in that keyring.
 49  *
 50  * If the description is NULL or an empty string, the key type is asked to
 51  * generate one from the payload.
 52  *
 53  * The keyring must be writable so that we can attach the key to it.
 54  *
 55  * If successful, the new key's serial number is returned, otherwise an error
 56  * code is returned.
 57  */
 58 SYSCALL_DEFINE5(add_key, const char __user *, _type,
 59                 const char __user *, _description,
 60                 const void __user *, _payload,
 61                 size_t, plen,
 62                 key_serial_t, ringid)
 63 {
 64         key_ref_t keyring_ref, key_ref;
 65         char type[32], *description;
 66         void *payload;
 67         long ret;
 68         bool vm;
 69 
 70         ret = -EINVAL;
 71         if (plen > 1024 * 1024 - 1)
 72                 goto error;
 73 
 74         /* draw all the data into kernel space */
 75         ret = key_get_type_from_user(type, _type, sizeof(type));
 76         if (ret < 0)
 77                 goto error;
 78 
 79         description = NULL;
 80         if (_description) {
 81                 description = strndup_user(_description, PAGE_SIZE);
 82                 if (IS_ERR(description)) {
 83                         ret = PTR_ERR(description);
 84                         goto error;
 85                 }
 86                 if (!*description) {
 87                         kfree(description);
 88                         description = NULL;
 89                 } else if ((description[0] == '.') &&
 90                            (strncmp(type, "keyring", 7) == 0)) {
 91                         ret = -EPERM;
 92                         goto error2;
 93                 }
 94         }
 95 
 96         /* pull the payload in if one was supplied */
 97         payload = NULL;
 98 
 99         vm = false;
100         if (_payload) {
101                 ret = -ENOMEM;
102                 payload = kmalloc(plen, GFP_KERNEL | __GFP_NOWARN);
103                 if (!payload) {
104                         if (plen <= PAGE_SIZE)
105                                 goto error2;
106                         vm = true;
107                         payload = vmalloc(plen);
108                         if (!payload)
109                                 goto error2;
110                 }
111 
112                 ret = -EFAULT;
113                 if (copy_from_user(payload, _payload, plen) != 0)
114                         goto error3;
115         }
116 
117         /* find the target keyring (which must be writable) */
118         keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
119         if (IS_ERR(keyring_ref)) {
120                 ret = PTR_ERR(keyring_ref);
121                 goto error3;
122         }
123 
124         /* create or update the requested key and add it to the target
125          * keyring */
126         key_ref = key_create_or_update(keyring_ref, type, description,
127                                        payload, plen, KEY_PERM_UNDEF,
128                                        KEY_ALLOC_IN_QUOTA);
129         if (!IS_ERR(key_ref)) {
130                 ret = key_ref_to_ptr(key_ref)->serial;
131                 key_ref_put(key_ref);
132         }
133         else {
134                 ret = PTR_ERR(key_ref);
135         }
136 
137         key_ref_put(keyring_ref);
138  error3:
139         if (!vm)
140                 kfree(payload);
141         else
142                 vfree(payload);
143  error2:
144         kfree(description);
145  error:
146         return ret;
147 }
148 
149 /*
150  * Search the process keyrings and keyring trees linked from those for a
151  * matching key.  Keyrings must have appropriate Search permission to be
152  * searched.
153  *
154  * If a key is found, it will be attached to the destination keyring if there's
155  * one specified and the serial number of the key will be returned.
156  *
157  * If no key is found, /sbin/request-key will be invoked if _callout_info is
158  * non-NULL in an attempt to create a key.  The _callout_info string will be
159  * passed to /sbin/request-key to aid with completing the request.  If the
160  * _callout_info string is "" then it will be changed to "-".
161  */
162 SYSCALL_DEFINE4(request_key, const char __user *, _type,
163                 const char __user *, _description,
164                 const char __user *, _callout_info,
165                 key_serial_t, destringid)
166 {
167         struct key_type *ktype;
168         struct key *key;
169         key_ref_t dest_ref;
170         size_t callout_len;
171         char type[32], *description, *callout_info;
172         long ret;
173 
174         /* pull the type into kernel space */
175         ret = key_get_type_from_user(type, _type, sizeof(type));
176         if (ret < 0)
177                 goto error;
178 
179         /* pull the description into kernel space */
180         description = strndup_user(_description, PAGE_SIZE);
181         if (IS_ERR(description)) {
182                 ret = PTR_ERR(description);
183                 goto error;
184         }
185 
186         /* pull the callout info into kernel space */
187         callout_info = NULL;
188         callout_len = 0;
189         if (_callout_info) {
190                 callout_info = strndup_user(_callout_info, PAGE_SIZE);
191                 if (IS_ERR(callout_info)) {
192                         ret = PTR_ERR(callout_info);
193                         goto error2;
194                 }
195                 callout_len = strlen(callout_info);
196         }
197 
198         /* get the destination keyring if specified */
199         dest_ref = NULL;
200         if (destringid) {
201                 dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
202                                            KEY_NEED_WRITE);
203                 if (IS_ERR(dest_ref)) {
204                         ret = PTR_ERR(dest_ref);
205                         goto error3;
206                 }
207         }
208 
209         /* find the key type */
210         ktype = key_type_lookup(type);
211         if (IS_ERR(ktype)) {
212                 ret = PTR_ERR(ktype);
213                 goto error4;
214         }
215 
216         /* do the search */
217         key = request_key_and_link(ktype, description, callout_info,
218                                    callout_len, NULL, key_ref_to_ptr(dest_ref),
219                                    KEY_ALLOC_IN_QUOTA);
220         if (IS_ERR(key)) {
221                 ret = PTR_ERR(key);
222                 goto error5;
223         }
224 
225         /* wait for the key to finish being constructed */
226         ret = wait_for_key_construction(key, 1);
227         if (ret < 0)
228                 goto error6;
229 
230         ret = key->serial;
231 
232 error6:
233         key_put(key);
234 error5:
235         key_type_put(ktype);
236 error4:
237         key_ref_put(dest_ref);
238 error3:
239         kfree(callout_info);
240 error2:
241         kfree(description);
242 error:
243         return ret;
244 }
245 
246 /*
247  * Get the ID of the specified process keyring.
248  *
249  * The requested keyring must have search permission to be found.
250  *
251  * If successful, the ID of the requested keyring will be returned.
252  */
253 long keyctl_get_keyring_ID(key_serial_t id, int create)
254 {
255         key_ref_t key_ref;
256         unsigned long lflags;
257         long ret;
258 
259         lflags = create ? KEY_LOOKUP_CREATE : 0;
260         key_ref = lookup_user_key(id, lflags, KEY_NEED_SEARCH);
261         if (IS_ERR(key_ref)) {
262                 ret = PTR_ERR(key_ref);
263                 goto error;
264         }
265 
266         ret = key_ref_to_ptr(key_ref)->serial;
267         key_ref_put(key_ref);
268 error:
269         return ret;
270 }
271 
272 /*
273  * Join a (named) session keyring.
274  *
275  * Create and join an anonymous session keyring or join a named session
276  * keyring, creating it if necessary.  A named session keyring must have Search
277  * permission for it to be joined.  Session keyrings without this permit will
278  * be skipped over.
279  *
280  * If successful, the ID of the joined session keyring will be returned.
281  */
282 long keyctl_join_session_keyring(const char __user *_name)
283 {
284         char *name;
285         long ret;
286 
287         /* fetch the name from userspace */
288         name = NULL;
289         if (_name) {
290                 name = strndup_user(_name, PAGE_SIZE);
291                 if (IS_ERR(name)) {
292                         ret = PTR_ERR(name);
293                         goto error;
294                 }
295         }
296 
297         /* join the session */
298         ret = join_session_keyring(name);
299         kfree(name);
300 
301 error:
302         return ret;
303 }
304 
305 /*
306  * Update a key's data payload from the given data.
307  *
308  * The key must grant the caller Write permission and the key type must support
309  * updating for this to work.  A negative key can be positively instantiated
310  * with this call.
311  *
312  * If successful, 0 will be returned.  If the key type does not support
313  * updating, then -EOPNOTSUPP will be returned.
314  */
315 long keyctl_update_key(key_serial_t id,
316                        const void __user *_payload,
317                        size_t plen)
318 {
319         key_ref_t key_ref;
320         void *payload;
321         long ret;
322 
323         ret = -EINVAL;
324         if (plen > PAGE_SIZE)
325                 goto error;
326 
327         /* pull the payload in if one was supplied */
328         payload = NULL;
329         if (_payload) {
330                 ret = -ENOMEM;
331                 payload = kmalloc(plen, GFP_KERNEL);
332                 if (!payload)
333                         goto error;
334 
335                 ret = -EFAULT;
336                 if (copy_from_user(payload, _payload, plen) != 0)
337                         goto error2;
338         }
339 
340         /* find the target key (which must be writable) */
341         key_ref = lookup_user_key(id, 0, KEY_NEED_WRITE);
342         if (IS_ERR(key_ref)) {
343                 ret = PTR_ERR(key_ref);
344                 goto error2;
345         }
346 
347         /* update the key */
348         ret = key_update(key_ref, payload, plen);
349 
350         key_ref_put(key_ref);
351 error2:
352         kfree(payload);
353 error:
354         return ret;
355 }
356 
357 /*
358  * Revoke a key.
359  *
360  * The key must be grant the caller Write or Setattr permission for this to
361  * work.  The key type should give up its quota claim when revoked.  The key
362  * and any links to the key will be automatically garbage collected after a
363  * certain amount of time (/proc/sys/kernel/keys/gc_delay).
364  *
365  * If successful, 0 is returned.
366  */
367 long keyctl_revoke_key(key_serial_t id)
368 {
369         key_ref_t key_ref;
370         long ret;
371 
372         key_ref = lookup_user_key(id, 0, KEY_NEED_WRITE);
373         if (IS_ERR(key_ref)) {
374                 ret = PTR_ERR(key_ref);
375                 if (ret != -EACCES)
376                         goto error;
377                 key_ref = lookup_user_key(id, 0, KEY_NEED_SETATTR);
378                 if (IS_ERR(key_ref)) {
379                         ret = PTR_ERR(key_ref);
380                         goto error;
381                 }
382         }
383 
384         key_revoke(key_ref_to_ptr(key_ref));
385         ret = 0;
386 
387         key_ref_put(key_ref);
388 error:
389         return ret;
390 }
391 
392 /*
393  * Invalidate a key.
394  *
395  * The key must be grant the caller Invalidate permission for this to work.
396  * The key and any links to the key will be automatically garbage collected
397  * immediately.
398  *
399  * If successful, 0 is returned.
400  */
401 long keyctl_invalidate_key(key_serial_t id)
402 {
403         key_ref_t key_ref;
404         long ret;
405 
406         kenter("%d", id);
407 
408         key_ref = lookup_user_key(id, 0, KEY_NEED_SEARCH);
409         if (IS_ERR(key_ref)) {
410                 ret = PTR_ERR(key_ref);
411 
412                 /* Root is permitted to invalidate certain special keys */
413                 if (capable(CAP_SYS_ADMIN)) {
414                         key_ref = lookup_user_key(id, 0, 0);
415                         if (IS_ERR(key_ref))
416                                 goto error;
417                         if (test_bit(KEY_FLAG_ROOT_CAN_INVAL,
418                                      &key_ref_to_ptr(key_ref)->flags))
419                                 goto invalidate;
420                         goto error_put;
421                 }
422 
423                 goto error;
424         }
425 
426 invalidate:
427         key_invalidate(key_ref_to_ptr(key_ref));
428         ret = 0;
429 error_put:
430         key_ref_put(key_ref);
431 error:
432         kleave(" = %ld", ret);
433         return ret;
434 }
435 
436 /*
437  * Clear the specified keyring, creating an empty process keyring if one of the
438  * special keyring IDs is used.
439  *
440  * The keyring must grant the caller Write permission for this to work.  If
441  * successful, 0 will be returned.
442  */
443 long keyctl_keyring_clear(key_serial_t ringid)
444 {
445         key_ref_t keyring_ref;
446         long ret;
447 
448         keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
449         if (IS_ERR(keyring_ref)) {
450                 ret = PTR_ERR(keyring_ref);
451 
452                 /* Root is permitted to invalidate certain special keyrings */
453                 if (capable(CAP_SYS_ADMIN)) {
454                         keyring_ref = lookup_user_key(ringid, 0, 0);
455                         if (IS_ERR(keyring_ref))
456                                 goto error;
457                         if (test_bit(KEY_FLAG_ROOT_CAN_CLEAR,
458                                      &key_ref_to_ptr(keyring_ref)->flags))
459                                 goto clear;
460                         goto error_put;
461                 }
462 
463                 goto error;
464         }
465 
466 clear:
467         ret = keyring_clear(key_ref_to_ptr(keyring_ref));
468 error_put:
469         key_ref_put(keyring_ref);
470 error:
471         return ret;
472 }
473 
474 /*
475  * Create a link from a keyring to a key if there's no matching key in the
476  * keyring, otherwise replace the link to the matching key with a link to the
477  * new key.
478  *
479  * The key must grant the caller Link permission and the the keyring must grant
480  * the caller Write permission.  Furthermore, if an additional link is created,
481  * the keyring's quota will be extended.
482  *
483  * If successful, 0 will be returned.
484  */
485 long keyctl_keyring_link(key_serial_t id, key_serial_t ringid)
486 {
487         key_ref_t keyring_ref, key_ref;
488         long ret;
489 
490         keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
491         if (IS_ERR(keyring_ref)) {
492                 ret = PTR_ERR(keyring_ref);
493                 goto error;
494         }
495 
496         key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE, KEY_NEED_LINK);
497         if (IS_ERR(key_ref)) {
498                 ret = PTR_ERR(key_ref);
499                 goto error2;
500         }
501 
502         ret = key_link(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));
503 
504         key_ref_put(key_ref);
505 error2:
506         key_ref_put(keyring_ref);
507 error:
508         return ret;
509 }
510 
511 /*
512  * Unlink a key from a keyring.
513  *
514  * The keyring must grant the caller Write permission for this to work; the key
515  * itself need not grant the caller anything.  If the last link to a key is
516  * removed then that key will be scheduled for destruction.
517  *
518  * If successful, 0 will be returned.
519  */
520 long keyctl_keyring_unlink(key_serial_t id, key_serial_t ringid)
521 {
522         key_ref_t keyring_ref, key_ref;
523         long ret;
524 
525         keyring_ref = lookup_user_key(ringid, 0, KEY_NEED_WRITE);
526         if (IS_ERR(keyring_ref)) {
527                 ret = PTR_ERR(keyring_ref);
528                 goto error;
529         }
530 
531         key_ref = lookup_user_key(id, KEY_LOOKUP_FOR_UNLINK, 0);
532         if (IS_ERR(key_ref)) {
533                 ret = PTR_ERR(key_ref);
534                 goto error2;
535         }
536 
537         ret = key_unlink(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));
538 
539         key_ref_put(key_ref);
540 error2:
541         key_ref_put(keyring_ref);
542 error:
543         return ret;
544 }
545 
546 /*
547  * Return a description of a key to userspace.
548  *
549  * The key must grant the caller View permission for this to work.
550  *
551  * If there's a buffer, we place up to buflen bytes of data into it formatted
552  * in the following way:
553  *
554  *      type;uid;gid;perm;description<NUL>
555  *
556  * If successful, we return the amount of description available, irrespective
557  * of how much we may have copied into the buffer.
558  */
559 long keyctl_describe_key(key_serial_t keyid,
560                          char __user *buffer,
561                          size_t buflen)
562 {
563         struct key *key, *instkey;
564         key_ref_t key_ref;
565         char *tmpbuf;
566         long ret;
567 
568         key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_NEED_VIEW);
569         if (IS_ERR(key_ref)) {
570                 /* viewing a key under construction is permitted if we have the
571                  * authorisation token handy */
572                 if (PTR_ERR(key_ref) == -EACCES) {
573                         instkey = key_get_instantiation_authkey(keyid);
574                         if (!IS_ERR(instkey)) {
575                                 key_put(instkey);
576                                 key_ref = lookup_user_key(keyid,
577                                                           KEY_LOOKUP_PARTIAL,
578                                                           0);
579                                 if (!IS_ERR(key_ref))
580                                         goto okay;
581                         }
582                 }
583 
584                 ret = PTR_ERR(key_ref);
585                 goto error;
586         }
587 
588 okay:
589         /* calculate how much description we're going to return */
590         ret = -ENOMEM;
591         tmpbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
592         if (!tmpbuf)
593                 goto error2;
594 
595         key = key_ref_to_ptr(key_ref);
596 
597         ret = snprintf(tmpbuf, PAGE_SIZE - 1,
598                        "%s;%d;%d;%08x;%s",
599                        key->type->name,
600                        from_kuid_munged(current_user_ns(), key->uid),
601                        from_kgid_munged(current_user_ns(), key->gid),
602                        key->perm,
603                        key->description ?: "");
604 
605         /* include a NUL char at the end of the data */
606         if (ret > PAGE_SIZE - 1)
607                 ret = PAGE_SIZE - 1;
608         tmpbuf[ret] = 0;
609         ret++;
610 
611         /* consider returning the data */
612         if (buffer && buflen > 0) {
613                 if (buflen > ret)
614                         buflen = ret;
615 
616                 if (copy_to_user(buffer, tmpbuf, buflen) != 0)
617                         ret = -EFAULT;
618         }
619 
620         kfree(tmpbuf);
621 error2:
622         key_ref_put(key_ref);
623 error:
624         return ret;
625 }
626 
627 /*
628  * Search the specified keyring and any keyrings it links to for a matching
629  * key.  Only keyrings that grant the caller Search permission will be searched
630  * (this includes the starting keyring).  Only keys with Search permission can
631  * be found.
632  *
633  * If successful, the found key will be linked to the destination keyring if
634  * supplied and the key has Link permission, and the found key ID will be
635  * returned.
636  */
637 long keyctl_keyring_search(key_serial_t ringid,
638                            const char __user *_type,
639                            const char __user *_description,
640                            key_serial_t destringid)
641 {
642         struct key_type *ktype;
643         key_ref_t keyring_ref, key_ref, dest_ref;
644         char type[32], *description;
645         long ret;
646 
647         /* pull the type and description into kernel space */
648         ret = key_get_type_from_user(type, _type, sizeof(type));
649         if (ret < 0)
650                 goto error;
651 
652         description = strndup_user(_description, PAGE_SIZE);
653         if (IS_ERR(description)) {
654                 ret = PTR_ERR(description);
655                 goto error;
656         }
657 
658         /* get the keyring at which to begin the search */
659         keyring_ref = lookup_user_key(ringid, 0, KEY_NEED_SEARCH);
660         if (IS_ERR(keyring_ref)) {
661                 ret = PTR_ERR(keyring_ref);
662                 goto error2;
663         }
664 
665         /* get the destination keyring if specified */
666         dest_ref = NULL;
667         if (destringid) {
668                 dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
669                                            KEY_NEED_WRITE);
670                 if (IS_ERR(dest_ref)) {
671                         ret = PTR_ERR(dest_ref);
672                         goto error3;
673                 }
674         }
675 
676         /* find the key type */
677         ktype = key_type_lookup(type);
678         if (IS_ERR(ktype)) {
679                 ret = PTR_ERR(ktype);
680                 goto error4;
681         }
682 
683         /* do the search */
684         key_ref = keyring_search(keyring_ref, ktype, description);
685         if (IS_ERR(key_ref)) {
686                 ret = PTR_ERR(key_ref);
687 
688                 /* treat lack or presence of a negative key the same */
689                 if (ret == -EAGAIN)
690                         ret = -ENOKEY;
691                 goto error5;
692         }
693 
694         /* link the resulting key to the destination keyring if we can */
695         if (dest_ref) {
696                 ret = key_permission(key_ref, KEY_NEED_LINK);
697                 if (ret < 0)
698                         goto error6;
699 
700                 ret = key_link(key_ref_to_ptr(dest_ref), key_ref_to_ptr(key_ref));
701                 if (ret < 0)
702                         goto error6;
703         }
704 
705         ret = key_ref_to_ptr(key_ref)->serial;
706 
707 error6:
708         key_ref_put(key_ref);
709 error5:
710         key_type_put(ktype);
711 error4:
712         key_ref_put(dest_ref);
713 error3:
714         key_ref_put(keyring_ref);
715 error2:
716         kfree(description);
717 error:
718         return ret;
719 }
720 
721 /*
722  * Read a key's payload.
723  *
724  * The key must either grant the caller Read permission, or it must grant the
725  * caller Search permission when searched for from the process keyrings.
726  *
727  * If successful, we place up to buflen bytes of data into the buffer, if one
728  * is provided, and return the amount of data that is available in the key,
729  * irrespective of how much we copied into the buffer.
730  */
731 long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen)
732 {
733         struct key *key;
734         key_ref_t key_ref;
735         long ret;
736 
737         /* find the key first */
738         key_ref = lookup_user_key(keyid, 0, 0);
739         if (IS_ERR(key_ref)) {
740                 ret = -ENOKEY;
741                 goto error;
742         }
743 
744         key = key_ref_to_ptr(key_ref);
745 
746         /* see if we can read it directly */
747         ret = key_permission(key_ref, KEY_NEED_READ);
748         if (ret == 0)
749                 goto can_read_key;
750         if (ret != -EACCES)
751                 goto error;
752 
753         /* we can't; see if it's searchable from this process's keyrings
754          * - we automatically take account of the fact that it may be
755          *   dangling off an instantiation key
756          */
757         if (!is_key_possessed(key_ref)) {
758                 ret = -EACCES;
759                 goto error2;
760         }
761 
762         /* the key is probably readable - now try to read it */
763 can_read_key:
764         ret = key_validate(key);
765         if (ret == 0) {
766                 ret = -EOPNOTSUPP;
767                 if (key->type->read) {
768                         /* read the data with the semaphore held (since we
769                          * might sleep) */
770                         down_read(&key->sem);
771                         ret = key->type->read(key, buffer, buflen);
772                         up_read(&key->sem);
773                 }
774         }
775 
776 error2:
777         key_put(key);
778 error:
779         return ret;
780 }
781 
782 /*
783  * Change the ownership of a key
784  *
785  * The key must grant the caller Setattr permission for this to work, though
786  * the key need not be fully instantiated yet.  For the UID to be changed, or
787  * for the GID to be changed to a group the caller is not a member of, the
788  * caller must have sysadmin capability.  If either uid or gid is -1 then that
789  * attribute is not changed.
790  *
791  * If the UID is to be changed, the new user must have sufficient quota to
792  * accept the key.  The quota deduction will be removed from the old user to
793  * the new user should the attribute be changed.
794  *
795  * If successful, 0 will be returned.
796  */
797 long keyctl_chown_key(key_serial_t id, uid_t user, gid_t group)
798 {
799         struct key_user *newowner, *zapowner = NULL;
800         struct key *key;
801         key_ref_t key_ref;
802         long ret;
803         kuid_t uid;
804         kgid_t gid;
805 
806         uid = make_kuid(current_user_ns(), user);
807         gid = make_kgid(current_user_ns(), group);
808         ret = -EINVAL;
809         if ((user != (uid_t) -1) && !uid_valid(uid))
810                 goto error;
811         if ((group != (gid_t) -1) && !gid_valid(gid))
812                 goto error;
813 
814         ret = 0;
815         if (user == (uid_t) -1 && group == (gid_t) -1)
816                 goto error;
817 
818         key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
819                                   KEY_NEED_SETATTR);
820         if (IS_ERR(key_ref)) {
821                 ret = PTR_ERR(key_ref);
822                 goto error;
823         }
824 
825         key = key_ref_to_ptr(key_ref);
826 
827         /* make the changes with the locks held to prevent chown/chown races */
828         ret = -EACCES;
829         down_write(&key->sem);
830 
831         if (!capable(CAP_SYS_ADMIN)) {
832                 /* only the sysadmin can chown a key to some other UID */
833                 if (user != (uid_t) -1 && !uid_eq(key->uid, uid))
834                         goto error_put;
835 
836                 /* only the sysadmin can set the key's GID to a group other
837                  * than one of those that the current process subscribes to */
838                 if (group != (gid_t) -1 && !gid_eq(gid, key->gid) && !in_group_p(gid))
839                         goto error_put;
840         }
841 
842         /* change the UID */
843         if (user != (uid_t) -1 && !uid_eq(uid, key->uid)) {
844                 ret = -ENOMEM;
845                 newowner = key_user_lookup(uid);
846                 if (!newowner)
847                         goto error_put;
848 
849                 /* transfer the quota burden to the new user */
850                 if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
851                         unsigned maxkeys = uid_eq(uid, GLOBAL_ROOT_UID) ?
852                                 key_quota_root_maxkeys : key_quota_maxkeys;
853                         unsigned maxbytes = uid_eq(uid, GLOBAL_ROOT_UID) ?
854                                 key_quota_root_maxbytes : key_quota_maxbytes;
855 
856                         spin_lock(&newowner->lock);
857                         if (newowner->qnkeys + 1 >= maxkeys ||
858                             newowner->qnbytes + key->quotalen >= maxbytes ||
859                             newowner->qnbytes + key->quotalen <
860                             newowner->qnbytes)
861                                 goto quota_overrun;
862 
863                         newowner->qnkeys++;
864                         newowner->qnbytes += key->quotalen;
865                         spin_unlock(&newowner->lock);
866 
867                         spin_lock(&key->user->lock);
868                         key->user->qnkeys--;
869                         key->user->qnbytes -= key->quotalen;
870                         spin_unlock(&key->user->lock);
871                 }
872 
873                 atomic_dec(&key->user->nkeys);
874                 atomic_inc(&newowner->nkeys);
875 
876                 if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
877                         atomic_dec(&key->user->nikeys);
878                         atomic_inc(&newowner->nikeys);
879                 }
880 
881                 zapowner = key->user;
882                 key->user = newowner;
883                 key->uid = uid;
884         }
885 
886         /* change the GID */
887         if (group != (gid_t) -1)
888                 key->gid = gid;
889 
890         ret = 0;
891 
892 error_put:
893         up_write(&key->sem);
894         key_put(key);
895         if (zapowner)
896                 key_user_put(zapowner);
897 error:
898         return ret;
899 
900 quota_overrun:
901         spin_unlock(&newowner->lock);
902         zapowner = newowner;
903         ret = -EDQUOT;
904         goto error_put;
905 }
906 
907 /*
908  * Change the permission mask on a key.
909  *
910  * The key must grant the caller Setattr permission for this to work, though
911  * the key need not be fully instantiated yet.  If the caller does not have
912  * sysadmin capability, it may only change the permission on keys that it owns.
913  */
914 long keyctl_setperm_key(key_serial_t id, key_perm_t perm)
915 {
916         struct key *key;
917         key_ref_t key_ref;
918         long ret;
919 
920         ret = -EINVAL;
921         if (perm & ~(KEY_POS_ALL | KEY_USR_ALL | KEY_GRP_ALL | KEY_OTH_ALL))
922                 goto error;
923 
924         key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
925                                   KEY_NEED_SETATTR);
926         if (IS_ERR(key_ref)) {
927                 ret = PTR_ERR(key_ref);
928                 goto error;
929         }
930 
931         key = key_ref_to_ptr(key_ref);
932 
933         /* make the changes with the locks held to prevent chown/chmod races */
934         ret = -EACCES;
935         down_write(&key->sem);
936 
937         /* if we're not the sysadmin, we can only change a key that we own */
938         if (capable(CAP_SYS_ADMIN) || uid_eq(key->uid, current_fsuid())) {
939                 key->perm = perm;
940                 ret = 0;
941         }
942 
943         up_write(&key->sem);
944         key_put(key);
945 error:
946         return ret;
947 }
948 
949 /*
950  * Get the destination keyring for instantiation and check that the caller has
951  * Write permission on it.
952  */
953 static long get_instantiation_keyring(key_serial_t ringid,
954                                       struct request_key_auth *rka,
955                                       struct key **_dest_keyring)
956 {
957         key_ref_t dkref;
958 
959         *_dest_keyring = NULL;
960 
961         /* just return a NULL pointer if we weren't asked to make a link */
962         if (ringid == 0)
963                 return 0;
964 
965         /* if a specific keyring is nominated by ID, then use that */
966         if (ringid > 0) {
967                 dkref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
968                 if (IS_ERR(dkref))
969                         return PTR_ERR(dkref);
970                 *_dest_keyring = key_ref_to_ptr(dkref);
971                 return 0;
972         }
973 
974         if (ringid == KEY_SPEC_REQKEY_AUTH_KEY)
975                 return -EINVAL;
976 
977         /* otherwise specify the destination keyring recorded in the
978          * authorisation key (any KEY_SPEC_*_KEYRING) */
979         if (ringid >= KEY_SPEC_REQUESTOR_KEYRING) {
980                 *_dest_keyring = key_get(rka->dest_keyring);
981                 return 0;
982         }
983 
984         return -ENOKEY;
985 }
986 
987 /*
988  * Change the request_key authorisation key on the current process.
989  */
990 static int keyctl_change_reqkey_auth(struct key *key)
991 {
992         struct cred *new;
993 
994         new = prepare_creds();
995         if (!new)
996                 return -ENOMEM;
997 
998         key_put(new->request_key_auth);
999         new->request_key_auth = key_get(key);
1000 
1001         return commit_creds(new);
1002 }
1003 
1004 /*
1005  * Copy the iovec data from userspace
1006  */
1007 static long copy_from_user_iovec(void *buffer, const struct iovec *iov,
1008                                  unsigned ioc)
1009 {
1010         for (; ioc > 0; ioc--) {
1011                 if (copy_from_user(buffer, iov->iov_base, iov->iov_len) != 0)
1012                         return -EFAULT;
1013                 buffer += iov->iov_len;
1014                 iov++;
1015         }
1016         return 0;
1017 }
1018 
1019 /*
1020  * Instantiate a key with the specified payload and link the key into the
1021  * destination keyring if one is given.
1022  *
1023  * The caller must have the appropriate instantiation permit set for this to
1024  * work (see keyctl_assume_authority).  No other permissions are required.
1025  *
1026  * If successful, 0 will be returned.
1027  */
1028 long keyctl_instantiate_key_common(key_serial_t id,
1029                                    const struct iovec *payload_iov,
1030                                    unsigned ioc,
1031                                    size_t plen,
1032                                    key_serial_t ringid)
1033 {
1034         const struct cred *cred = current_cred();
1035         struct request_key_auth *rka;
1036         struct key *instkey, *dest_keyring;
1037         void *payload;
1038         long ret;
1039         bool vm = false;
1040 
1041         kenter("%d,,%zu,%d", id, plen, ringid);
1042 
1043         ret = -EINVAL;
1044         if (plen > 1024 * 1024 - 1)
1045                 goto error;
1046 
1047         /* the appropriate instantiation authorisation key must have been
1048          * assumed before calling this */
1049         ret = -EPERM;
1050         instkey = cred->request_key_auth;
1051         if (!instkey)
1052                 goto error;
1053 
1054         rka = instkey->payload.data;
1055         if (rka->target_key->serial != id)
1056                 goto error;
1057 
1058         /* pull the payload in if one was supplied */
1059         payload = NULL;
1060 
1061         if (payload_iov) {
1062                 ret = -ENOMEM;
1063                 payload = kmalloc(plen, GFP_KERNEL);
1064                 if (!payload) {
1065                         if (plen <= PAGE_SIZE)
1066                                 goto error;
1067                         vm = true;
1068                         payload = vmalloc(plen);
1069                         if (!payload)
1070                                 goto error;
1071                 }
1072 
1073                 ret = copy_from_user_iovec(payload, payload_iov, ioc);
1074                 if (ret < 0)
1075                         goto error2;
1076         }
1077 
1078         /* find the destination keyring amongst those belonging to the
1079          * requesting task */
1080         ret = get_instantiation_keyring(ringid, rka, &dest_keyring);
1081         if (ret < 0)
1082                 goto error2;
1083 
1084         /* instantiate the key and link it into a keyring */
1085         ret = key_instantiate_and_link(rka->target_key, payload, plen,
1086                                        dest_keyring, instkey);
1087 
1088         key_put(dest_keyring);
1089 
1090         /* discard the assumed authority if it's just been disabled by
1091          * instantiation of the key */
1092         if (ret == 0)
1093                 keyctl_change_reqkey_auth(NULL);
1094 
1095 error2:
1096         if (!vm)
1097                 kfree(payload);
1098         else
1099                 vfree(payload);
1100 error:
1101         return ret;
1102 }
1103 
1104 /*
1105  * Instantiate a key with the specified payload and link the key into the
1106  * destination keyring if one is given.
1107  *
1108  * The caller must have the appropriate instantiation permit set for this to
1109  * work (see keyctl_assume_authority).  No other permissions are required.
1110  *
1111  * If successful, 0 will be returned.
1112  */
1113 long keyctl_instantiate_key(key_serial_t id,
1114                             const void __user *_payload,
1115                             size_t plen,
1116                             key_serial_t ringid)
1117 {
1118         if (_payload && plen) {
1119                 struct iovec iov[1] = {
1120                         [0].iov_base = (void __user *)_payload,
1121                         [0].iov_len  = plen
1122                 };
1123 
1124                 return keyctl_instantiate_key_common(id, iov, 1, plen, ringid);
1125         }
1126 
1127         return keyctl_instantiate_key_common(id, NULL, 0, 0, ringid);
1128 }
1129 
1130 /*
1131  * Instantiate a key with the specified multipart payload and link the key into
1132  * the destination keyring if one is given.
1133  *
1134  * The caller must have the appropriate instantiation permit set for this to
1135  * work (see keyctl_assume_authority).  No other permissions are required.
1136  *
1137  * If successful, 0 will be returned.
1138  */
1139 long keyctl_instantiate_key_iov(key_serial_t id,
1140                                 const struct iovec __user *_payload_iov,
1141                                 unsigned ioc,
1142                                 key_serial_t ringid)
1143 {
1144         struct iovec iovstack[UIO_FASTIOV], *iov = iovstack;
1145         long ret;
1146 
1147         if (!_payload_iov || !ioc)
1148                 goto no_payload;
1149 
1150         ret = rw_copy_check_uvector(WRITE, _payload_iov, ioc,
1151                                     ARRAY_SIZE(iovstack), iovstack, &iov);
1152         if (ret < 0)
1153                 goto err;
1154         if (ret == 0)
1155                 goto no_payload_free;
1156 
1157         ret = keyctl_instantiate_key_common(id, iov, ioc, ret, ringid);
1158 err:
1159         if (iov != iovstack)
1160                 kfree(iov);
1161         return ret;
1162 
1163 no_payload_free:
1164         if (iov != iovstack)
1165                 kfree(iov);
1166 no_payload:
1167         return keyctl_instantiate_key_common(id, NULL, 0, 0, ringid);
1168 }
1169 
1170 /*
1171  * Negatively instantiate the key with the given timeout (in seconds) and link
1172  * the key into the destination keyring if one is given.
1173  *
1174  * The caller must have the appropriate instantiation permit set for this to
1175  * work (see keyctl_assume_authority).  No other permissions are required.
1176  *
1177  * The key and any links to the key will be automatically garbage collected
1178  * after the timeout expires.
1179  *
1180  * Negative keys are used to rate limit repeated request_key() calls by causing
1181  * them to return -ENOKEY until the negative key expires.
1182  *
1183  * If successful, 0 will be returned.
1184  */
1185 long keyctl_negate_key(key_serial_t id, unsigned timeout, key_serial_t ringid)
1186 {
1187         return keyctl_reject_key(id, timeout, ENOKEY, ringid);
1188 }
1189 
1190 /*
1191  * Negatively instantiate the key with the given timeout (in seconds) and error
1192  * code and link the key into the destination keyring if one is given.
1193  *
1194  * The caller must have the appropriate instantiation permit set for this to
1195  * work (see keyctl_assume_authority).  No other permissions are required.
1196  *
1197  * The key and any links to the key will be automatically garbage collected
1198  * after the timeout expires.
1199  *
1200  * Negative keys are used to rate limit repeated request_key() calls by causing
1201  * them to return the specified error code until the negative key expires.
1202  *
1203  * If successful, 0 will be returned.
1204  */
1205 long keyctl_reject_key(key_serial_t id, unsigned timeout, unsigned error,
1206                        key_serial_t ringid)
1207 {
1208         const struct cred *cred = current_cred();
1209         struct request_key_auth *rka;
1210         struct key *instkey, *dest_keyring;
1211         long ret;
1212 
1213         kenter("%d,%u,%u,%d", id, timeout, error, ringid);
1214 
1215         /* must be a valid error code and mustn't be a kernel special */
1216         if (error <= 0 ||
1217             error >= MAX_ERRNO ||
1218             error == ERESTARTSYS ||
1219             error == ERESTARTNOINTR ||
1220             error == ERESTARTNOHAND ||
1221             error == ERESTART_RESTARTBLOCK)
1222                 return -EINVAL;
1223 
1224         /* the appropriate instantiation authorisation key must have been
1225          * assumed before calling this */
1226         ret = -EPERM;
1227         instkey = cred->request_key_auth;
1228         if (!instkey)
1229                 goto error;
1230 
1231         rka = instkey->payload.data;
1232         if (rka->target_key->serial != id)
1233                 goto error;
1234 
1235         /* find the destination keyring if present (which must also be
1236          * writable) */
1237         ret = get_instantiation_keyring(ringid, rka, &dest_keyring);
1238         if (ret < 0)
1239                 goto error;
1240 
1241         /* instantiate the key and link it into a keyring */
1242         ret = key_reject_and_link(rka->target_key, timeout, error,
1243                                   dest_keyring, instkey);
1244 
1245         key_put(dest_keyring);
1246 
1247         /* discard the assumed authority if it's just been disabled by
1248          * instantiation of the key */
1249         if (ret == 0)
1250                 keyctl_change_reqkey_auth(NULL);
1251 
1252 error:
1253         return ret;
1254 }
1255 
1256 /*
1257  * Read or set the default keyring in which request_key() will cache keys and
1258  * return the old setting.
1259  *
1260  * If a process keyring is specified then this will be created if it doesn't
1261  * yet exist.  The old setting will be returned if successful.
1262  */
1263 long keyctl_set_reqkey_keyring(int reqkey_defl)
1264 {
1265         struct cred *new;
1266         int ret, old_setting;
1267 
1268         old_setting = current_cred_xxx(jit_keyring);
1269 
1270         if (reqkey_defl == KEY_REQKEY_DEFL_NO_CHANGE)
1271                 return old_setting;
1272 
1273         new = prepare_creds();
1274         if (!new)
1275                 return -ENOMEM;
1276 
1277         switch (reqkey_defl) {
1278         case KEY_REQKEY_DEFL_THREAD_KEYRING:
1279                 ret = install_thread_keyring_to_cred(new);
1280                 if (ret < 0)
1281                         goto error;
1282                 goto set;
1283 
1284         case KEY_REQKEY_DEFL_PROCESS_KEYRING:
1285                 ret = install_process_keyring_to_cred(new);
1286                 if (ret < 0) {
1287                         if (ret != -EEXIST)
1288                                 goto error;
1289                         ret = 0;
1290                 }
1291                 goto set;
1292 
1293         case KEY_REQKEY_DEFL_DEFAULT:
1294         case KEY_REQKEY_DEFL_SESSION_KEYRING:
1295         case KEY_REQKEY_DEFL_USER_KEYRING:
1296         case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
1297         case KEY_REQKEY_DEFL_REQUESTOR_KEYRING:
1298                 goto set;
1299 
1300         case KEY_REQKEY_DEFL_NO_CHANGE:
1301         case KEY_REQKEY_DEFL_GROUP_KEYRING:
1302         default:
1303                 ret = -EINVAL;
1304                 goto error;
1305         }
1306 
1307 set:
1308         new->jit_keyring = reqkey_defl;
1309         commit_creds(new);
1310         return old_setting;
1311 error:
1312         abort_creds(new);
1313         return ret;
1314 }
1315 
1316 /*
1317  * Set or clear the timeout on a key.
1318  *
1319  * Either the key must grant the caller Setattr permission or else the caller
1320  * must hold an instantiation authorisation token for the key.
1321  *
1322  * The timeout is either 0 to clear the timeout, or a number of seconds from
1323  * the current time.  The key and any links to the key will be automatically
1324  * garbage collected after the timeout expires.
1325  *
1326  * If successful, 0 is returned.
1327  */
1328 long keyctl_set_timeout(key_serial_t id, unsigned timeout)
1329 {
1330         struct key *key, *instkey;
1331         key_ref_t key_ref;
1332         long ret;
1333 
1334         key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
1335                                   KEY_NEED_SETATTR);
1336         if (IS_ERR(key_ref)) {
1337                 /* setting the timeout on a key under construction is permitted
1338                  * if we have the authorisation token handy */
1339                 if (PTR_ERR(key_ref) == -EACCES) {
1340                         instkey = key_get_instantiation_authkey(id);
1341                         if (!IS_ERR(instkey)) {
1342                                 key_put(instkey);
1343                                 key_ref = lookup_user_key(id,
1344                                                           KEY_LOOKUP_PARTIAL,
1345                                                           0);
1346                                 if (!IS_ERR(key_ref))
1347                                         goto okay;
1348                         }
1349                 }
1350 
1351                 ret = PTR_ERR(key_ref);
1352                 goto error;
1353         }
1354 
1355 okay:
1356         key = key_ref_to_ptr(key_ref);
1357         key_set_timeout(key, timeout);
1358         key_put(key);
1359 
1360         ret = 0;
1361 error:
1362         return ret;
1363 }
1364 
1365 /*
1366  * Assume (or clear) the authority to instantiate the specified key.
1367  *
1368  * This sets the authoritative token currently in force for key instantiation.
1369  * This must be done for a key to be instantiated.  It has the effect of making
1370  * available all the keys from the caller of the request_key() that created a
1371  * key to request_key() calls made by the caller of this function.
1372  *
1373  * The caller must have the instantiation key in their process keyrings with a
1374  * Search permission grant available to the caller.
1375  *
1376  * If the ID given is 0, then the setting will be cleared and 0 returned.
1377  *
1378  * If the ID given has a matching an authorisation key, then that key will be
1379  * set and its ID will be returned.  The authorisation key can be read to get
1380  * the callout information passed to request_key().
1381  */
1382 long keyctl_assume_authority(key_serial_t id)
1383 {
1384         struct key *authkey;
1385         long ret;
1386 
1387         /* special key IDs aren't permitted */
1388         ret = -EINVAL;
1389         if (id < 0)
1390                 goto error;
1391 
1392         /* we divest ourselves of authority if given an ID of 0 */
1393         if (id == 0) {
1394                 ret = keyctl_change_reqkey_auth(NULL);
1395                 goto error;
1396         }
1397 
1398         /* attempt to assume the authority temporarily granted to us whilst we
1399          * instantiate the specified key
1400          * - the authorisation key must be in the current task's keyrings
1401          *   somewhere
1402          */
1403         authkey = key_get_instantiation_authkey(id);
1404         if (IS_ERR(authkey)) {
1405                 ret = PTR_ERR(authkey);
1406                 goto error;
1407         }
1408 
1409         ret = keyctl_change_reqkey_auth(authkey);
1410         if (ret < 0)
1411                 goto error;
1412         key_put(authkey);
1413 
1414         ret = authkey->serial;
1415 error:
1416         return ret;
1417 }
1418 
1419 /*
1420  * Get a key's the LSM security label.
1421  *
1422  * The key must grant the caller View permission for this to work.
1423  *
1424  * If there's a buffer, then up to buflen bytes of data will be placed into it.
1425  *
1426  * If successful, the amount of information available will be returned,
1427  * irrespective of how much was copied (including the terminal NUL).
1428  */
1429 long keyctl_get_security(key_serial_t keyid,
1430                          char __user *buffer,
1431                          size_t buflen)
1432 {
1433         struct key *key, *instkey;
1434         key_ref_t key_ref;
1435         char *context;
1436         long ret;
1437 
1438         key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_NEED_VIEW);
1439         if (IS_ERR(key_ref)) {
1440                 if (PTR_ERR(key_ref) != -EACCES)
1441                         return PTR_ERR(key_ref);
1442 
1443                 /* viewing a key under construction is also permitted if we
1444                  * have the authorisation token handy */
1445                 instkey = key_get_instantiation_authkey(keyid);
1446                 if (IS_ERR(instkey))
1447                         return PTR_ERR(instkey);
1448                 key_put(instkey);
1449 
1450                 key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, 0);
1451                 if (IS_ERR(key_ref))
1452                         return PTR_ERR(key_ref);
1453         }
1454 
1455         key = key_ref_to_ptr(key_ref);
1456         ret = security_key_getsecurity(key, &context);
1457         if (ret == 0) {
1458                 /* if no information was returned, give userspace an empty
1459                  * string */
1460                 ret = 1;
1461                 if (buffer && buflen > 0 &&
1462                     copy_to_user(buffer, "", 1) != 0)
1463                         ret = -EFAULT;
1464         } else if (ret > 0) {
1465                 /* return as much data as there's room for */
1466                 if (buffer && buflen > 0) {
1467                         if (buflen > ret)
1468                                 buflen = ret;
1469 
1470                         if (copy_to_user(buffer, context, buflen) != 0)
1471                                 ret = -EFAULT;
1472                 }
1473 
1474                 kfree(context);
1475         }
1476 
1477         key_ref_put(key_ref);
1478         return ret;
1479 }
1480 
1481 /*
1482  * Attempt to install the calling process's session keyring on the process's
1483  * parent process.
1484  *
1485  * The keyring must exist and must grant the caller LINK permission, and the
1486  * parent process must be single-threaded and must have the same effective
1487  * ownership as this process and mustn't be SUID/SGID.
1488  *
1489  * The keyring will be emplaced on the parent when it next resumes userspace.
1490  *
1491  * If successful, 0 will be returned.
1492  */
1493 long keyctl_session_to_parent(void)
1494 {
1495         struct task_struct *me, *parent;
1496         const struct cred *mycred, *pcred;
1497         struct callback_head *newwork, *oldwork;
1498         key_ref_t keyring_r;
1499         struct cred *cred;
1500         int ret;
1501 
1502         keyring_r = lookup_user_key(KEY_SPEC_SESSION_KEYRING, 0, KEY_NEED_LINK);
1503         if (IS_ERR(keyring_r))
1504                 return PTR_ERR(keyring_r);
1505 
1506         ret = -ENOMEM;
1507 
1508         /* our parent is going to need a new cred struct, a new tgcred struct
1509          * and new security data, so we allocate them here to prevent ENOMEM in
1510          * our parent */
1511         cred = cred_alloc_blank();
1512         if (!cred)
1513                 goto error_keyring;
1514         newwork = &cred->rcu;
1515 
1516         cred->session_keyring = key_ref_to_ptr(keyring_r);
1517         keyring_r = NULL;
1518         init_task_work(newwork, key_change_session_keyring);
1519 
1520         me = current;
1521         rcu_read_lock();
1522         write_lock_irq(&tasklist_lock);
1523 
1524         ret = -EPERM;
1525         oldwork = NULL;
1526         parent = me->real_parent;
1527 
1528         /* the parent mustn't be init and mustn't be a kernel thread */
1529         if (parent->pid <= 1 || !parent->mm)
1530                 goto unlock;
1531 
1532         /* the parent must be single threaded */
1533         if (!thread_group_empty(parent))
1534                 goto unlock;
1535 
1536         /* the parent and the child must have different session keyrings or
1537          * there's no point */
1538         mycred = current_cred();
1539         pcred = __task_cred(parent);
1540         if (mycred == pcred ||
1541             mycred->session_keyring == pcred->session_keyring) {
1542                 ret = 0;
1543                 goto unlock;
1544         }
1545 
1546         /* the parent must have the same effective ownership and mustn't be
1547          * SUID/SGID */
1548         if (!uid_eq(pcred->uid,  mycred->euid) ||
1549             !uid_eq(pcred->euid, mycred->euid) ||
1550             !uid_eq(pcred->suid, mycred->euid) ||
1551             !gid_eq(pcred->gid,  mycred->egid) ||
1552             !gid_eq(pcred->egid, mycred->egid) ||
1553             !gid_eq(pcred->sgid, mycred->egid))
1554                 goto unlock;
1555 
1556         /* the keyrings must have the same UID */
1557         if ((pcred->session_keyring &&
1558              !uid_eq(pcred->session_keyring->uid, mycred->euid)) ||
1559             !uid_eq(mycred->session_keyring->uid, mycred->euid))
1560                 goto unlock;
1561 
1562         /* cancel an already pending keyring replacement */
1563         oldwork = task_work_cancel(parent, key_change_session_keyring);
1564 
1565         /* the replacement session keyring is applied just prior to userspace
1566          * restarting */
1567         ret = task_work_add(parent, newwork, true);
1568         if (!ret)
1569                 newwork = NULL;
1570 unlock:
1571         write_unlock_irq(&tasklist_lock);
1572         rcu_read_unlock();
1573         if (oldwork)
1574                 put_cred(container_of(oldwork, struct cred, rcu));
1575         if (newwork)
1576                 put_cred(cred);
1577         return ret;
1578 
1579 error_keyring:
1580         key_ref_put(keyring_r);
1581         return ret;
1582 }
1583 
1584 /*
1585  * The key control system call
1586  */
1587 SYSCALL_DEFINE5(keyctl, int, option, unsigned long, arg2, unsigned long, arg3,
1588                 unsigned long, arg4, unsigned long, arg5)
1589 {
1590         switch (option) {
1591         case KEYCTL_GET_KEYRING_ID:
1592                 return keyctl_get_keyring_ID((key_serial_t) arg2,
1593                                              (int) arg3);
1594 
1595         case KEYCTL_JOIN_SESSION_KEYRING:
1596                 return keyctl_join_session_keyring((const char __user *) arg2);
1597 
1598         case KEYCTL_UPDATE:
1599                 return keyctl_update_key((key_serial_t) arg2,
1600                                          (const void __user *) arg3,
1601                                          (size_t) arg4);
1602 
1603         case KEYCTL_REVOKE:
1604                 return keyctl_revoke_key((key_serial_t) arg2);
1605 
1606         case KEYCTL_DESCRIBE:
1607                 return keyctl_describe_key((key_serial_t) arg2,
1608                                            (char __user *) arg3,
1609                                            (unsigned) arg4);
1610 
1611         case KEYCTL_CLEAR:
1612                 return keyctl_keyring_clear((key_serial_t) arg2);
1613 
1614         case KEYCTL_LINK:
1615                 return keyctl_keyring_link((key_serial_t) arg2,
1616                                            (key_serial_t) arg3);
1617 
1618         case KEYCTL_UNLINK:
1619                 return keyctl_keyring_unlink((key_serial_t) arg2,
1620                                              (key_serial_t) arg3);
1621 
1622         case KEYCTL_SEARCH:
1623                 return keyctl_keyring_search((key_serial_t) arg2,
1624                                              (const char __user *) arg3,
1625                                              (const char __user *) arg4,
1626                                              (key_serial_t) arg5);
1627 
1628         case KEYCTL_READ:
1629                 return keyctl_read_key((key_serial_t) arg2,
1630                                        (char __user *) arg3,
1631                                        (size_t) arg4);
1632 
1633         case KEYCTL_CHOWN:
1634                 return keyctl_chown_key((key_serial_t) arg2,
1635                                         (uid_t) arg3,
1636                                         (gid_t) arg4);
1637 
1638         case KEYCTL_SETPERM:
1639                 return keyctl_setperm_key((key_serial_t) arg2,
1640                                           (key_perm_t) arg3);
1641 
1642         case KEYCTL_INSTANTIATE:
1643                 return keyctl_instantiate_key((key_serial_t) arg2,
1644                                               (const void __user *) arg3,
1645                                               (size_t) arg4,
1646                                               (key_serial_t) arg5);
1647 
1648         case KEYCTL_NEGATE:
1649                 return keyctl_negate_key((key_serial_t) arg2,
1650                                          (unsigned) arg3,
1651                                          (key_serial_t) arg4);
1652 
1653         case KEYCTL_SET_REQKEY_KEYRING:
1654                 return keyctl_set_reqkey_keyring(arg2);
1655 
1656         case KEYCTL_SET_TIMEOUT:
1657                 return keyctl_set_timeout((key_serial_t) arg2,
1658                                           (unsigned) arg3);
1659 
1660         case KEYCTL_ASSUME_AUTHORITY:
1661                 return keyctl_assume_authority((key_serial_t) arg2);
1662 
1663         case KEYCTL_GET_SECURITY:
1664                 return keyctl_get_security((key_serial_t) arg2,
1665                                            (char __user *) arg3,
1666                                            (size_t) arg4);
1667 
1668         case KEYCTL_SESSION_TO_PARENT:
1669                 return keyctl_session_to_parent();
1670 
1671         case KEYCTL_REJECT:
1672                 return keyctl_reject_key((key_serial_t) arg2,
1673                                          (unsigned) arg3,
1674                                          (unsigned) arg4,
1675                                          (key_serial_t) arg5);
1676 
1677         case KEYCTL_INSTANTIATE_IOV:
1678                 return keyctl_instantiate_key_iov(
1679                         (key_serial_t) arg2,
1680                         (const struct iovec __user *) arg3,
1681                         (unsigned) arg4,
1682                         (key_serial_t) arg5);
1683 
1684         case KEYCTL_INVALIDATE:
1685                 return keyctl_invalidate_key((key_serial_t) arg2);
1686 
1687         case KEYCTL_GET_PERSISTENT:
1688                 return keyctl_get_persistent((uid_t)arg2, (key_serial_t)arg3);
1689 
1690         default:
1691                 return -EOPNOTSUPP;
1692         }
1693 }
1694 

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