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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 #define KEY_MAX_DESC_SIZE 4096
 30 
 31 static int key_get_type_from_user(char *type,
 32                                   const char __user *_type,
 33                                   unsigned len)
 34 {
 35         int ret;
 36 
 37         ret = strncpy_from_user(type, _type, len);
 38         if (ret < 0)
 39                 return ret;
 40         if (ret == 0 || ret >= len)
 41                 return -EINVAL;
 42         if (type[0] == '.')
 43                 return -EPERM;
 44         type[len - 1] = '\0';
 45         return 0;
 46 }
 47 
 48 /*
 49  * Extract the description of a new key from userspace and either add it as a
 50  * new key to the specified keyring or update a matching key in that keyring.
 51  *
 52  * If the description is NULL or an empty string, the key type is asked to
 53  * generate one from the payload.
 54  *
 55  * The keyring must be writable so that we can attach the key to it.
 56  *
 57  * If successful, the new key's serial number is returned, otherwise an error
 58  * code is returned.
 59  */
 60 SYSCALL_DEFINE5(add_key, const char __user *, _type,
 61                 const char __user *, _description,
 62                 const void __user *, _payload,
 63                 size_t, plen,
 64                 key_serial_t, ringid)
 65 {
 66         key_ref_t keyring_ref, key_ref;
 67         char type[32], *description;
 68         void *payload;
 69         long ret;
 70         bool vm;
 71 
 72         ret = -EINVAL;
 73         if (plen > 1024 * 1024 - 1)
 74                 goto error;
 75 
 76         /* draw all the data into kernel space */
 77         ret = key_get_type_from_user(type, _type, sizeof(type));
 78         if (ret < 0)
 79                 goto error;
 80 
 81         description = NULL;
 82         if (_description) {
 83                 description = strndup_user(_description, KEY_MAX_DESC_SIZE);
 84                 if (IS_ERR(description)) {
 85                         ret = PTR_ERR(description);
 86                         goto error;
 87                 }
 88                 if (!*description) {
 89                         kfree(description);
 90                         description = NULL;
 91                 } else if ((description[0] == '.') &&
 92                            (strncmp(type, "keyring", 7) == 0)) {
 93                         ret = -EPERM;
 94                         goto error2;
 95                 }
 96         }
 97 
 98         /* pull the payload in if one was supplied */
 99         payload = NULL;
100 
101         vm = false;
102         if (_payload) {
103                 ret = -ENOMEM;
104                 payload = kmalloc(plen, GFP_KERNEL | __GFP_NOWARN);
105                 if (!payload) {
106                         if (plen <= PAGE_SIZE)
107                                 goto error2;
108                         vm = true;
109                         payload = vmalloc(plen);
110                         if (!payload)
111                                 goto error2;
112                 }
113 
114                 ret = -EFAULT;
115                 if (copy_from_user(payload, _payload, plen) != 0)
116                         goto error3;
117         }
118 
119         /* find the target keyring (which must be writable) */
120         keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
121         if (IS_ERR(keyring_ref)) {
122                 ret = PTR_ERR(keyring_ref);
123                 goto error3;
124         }
125 
126         /* create or update the requested key and add it to the target
127          * keyring */
128         key_ref = key_create_or_update(keyring_ref, type, description,
129                                        payload, plen, KEY_PERM_UNDEF,
130                                        KEY_ALLOC_IN_QUOTA);
131         if (!IS_ERR(key_ref)) {
132                 ret = key_ref_to_ptr(key_ref)->serial;
133                 key_ref_put(key_ref);
134         }
135         else {
136                 ret = PTR_ERR(key_ref);
137         }
138 
139         key_ref_put(keyring_ref);
140  error3:
141         if (!vm)
142                 kfree(payload);
143         else
144                 vfree(payload);
145  error2:
146         kfree(description);
147  error:
148         return ret;
149 }
150 
151 /*
152  * Search the process keyrings and keyring trees linked from those for a
153  * matching key.  Keyrings must have appropriate Search permission to be
154  * searched.
155  *
156  * If a key is found, it will be attached to the destination keyring if there's
157  * one specified and the serial number of the key will be returned.
158  *
159  * If no key is found, /sbin/request-key will be invoked if _callout_info is
160  * non-NULL in an attempt to create a key.  The _callout_info string will be
161  * passed to /sbin/request-key to aid with completing the request.  If the
162  * _callout_info string is "" then it will be changed to "-".
163  */
164 SYSCALL_DEFINE4(request_key, const char __user *, _type,
165                 const char __user *, _description,
166                 const char __user *, _callout_info,
167                 key_serial_t, destringid)
168 {
169         struct key_type *ktype;
170         struct key *key;
171         key_ref_t dest_ref;
172         size_t callout_len;
173         char type[32], *description, *callout_info;
174         long ret;
175 
176         /* pull the type into kernel space */
177         ret = key_get_type_from_user(type, _type, sizeof(type));
178         if (ret < 0)
179                 goto error;
180 
181         /* pull the description into kernel space */
182         description = strndup_user(_description, KEY_MAX_DESC_SIZE);
183         if (IS_ERR(description)) {
184                 ret = PTR_ERR(description);
185                 goto error;
186         }
187 
188         /* pull the callout info into kernel space */
189         callout_info = NULL;
190         callout_len = 0;
191         if (_callout_info) {
192                 callout_info = strndup_user(_callout_info, PAGE_SIZE);
193                 if (IS_ERR(callout_info)) {
194                         ret = PTR_ERR(callout_info);
195                         goto error2;
196                 }
197                 callout_len = strlen(callout_info);
198         }
199 
200         /* get the destination keyring if specified */
201         dest_ref = NULL;
202         if (destringid) {
203                 dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
204                                            KEY_NEED_WRITE);
205                 if (IS_ERR(dest_ref)) {
206                         ret = PTR_ERR(dest_ref);
207                         goto error3;
208                 }
209         }
210 
211         /* find the key type */
212         ktype = key_type_lookup(type);
213         if (IS_ERR(ktype)) {
214                 ret = PTR_ERR(ktype);
215                 goto error4;
216         }
217 
218         /* do the search */
219         key = request_key_and_link(ktype, description, callout_info,
220                                    callout_len, NULL, key_ref_to_ptr(dest_ref),
221                                    KEY_ALLOC_IN_QUOTA);
222         if (IS_ERR(key)) {
223                 ret = PTR_ERR(key);
224                 goto error5;
225         }
226 
227         /* wait for the key to finish being constructed */
228         ret = wait_for_key_construction(key, 1);
229         if (ret < 0)
230                 goto error6;
231 
232         ret = key->serial;
233 
234 error6:
235         key_put(key);
236 error5:
237         key_type_put(ktype);
238 error4:
239         key_ref_put(dest_ref);
240 error3:
241         kfree(callout_info);
242 error2:
243         kfree(description);
244 error:
245         return ret;
246 }
247 
248 /*
249  * Get the ID of the specified process keyring.
250  *
251  * The requested keyring must have search permission to be found.
252  *
253  * If successful, the ID of the requested keyring will be returned.
254  */
255 long keyctl_get_keyring_ID(key_serial_t id, int create)
256 {
257         key_ref_t key_ref;
258         unsigned long lflags;
259         long ret;
260 
261         lflags = create ? KEY_LOOKUP_CREATE : 0;
262         key_ref = lookup_user_key(id, lflags, KEY_NEED_SEARCH);
263         if (IS_ERR(key_ref)) {
264                 ret = PTR_ERR(key_ref);
265                 goto error;
266         }
267 
268         ret = key_ref_to_ptr(key_ref)->serial;
269         key_ref_put(key_ref);
270 error:
271         return ret;
272 }
273 
274 /*
275  * Join a (named) session keyring.
276  *
277  * Create and join an anonymous session keyring or join a named session
278  * keyring, creating it if necessary.  A named session keyring must have Search
279  * permission for it to be joined.  Session keyrings without this permit will
280  * be skipped over.
281  *
282  * If successful, the ID of the joined session keyring will be returned.
283  */
284 long keyctl_join_session_keyring(const char __user *_name)
285 {
286         char *name;
287         long ret;
288 
289         /* fetch the name from userspace */
290         name = NULL;
291         if (_name) {
292                 name = strndup_user(_name, KEY_MAX_DESC_SIZE);
293                 if (IS_ERR(name)) {
294                         ret = PTR_ERR(name);
295                         goto error;
296                 }
297         }
298 
299         /* join the session */
300         ret = join_session_keyring(name);
301         kfree(name);
302 
303 error:
304         return ret;
305 }
306 
307 /*
308  * Update a key's data payload from the given data.
309  *
310  * The key must grant the caller Write permission and the key type must support
311  * updating for this to work.  A negative key can be positively instantiated
312  * with this call.
313  *
314  * If successful, 0 will be returned.  If the key type does not support
315  * updating, then -EOPNOTSUPP will be returned.
316  */
317 long keyctl_update_key(key_serial_t id,
318                        const void __user *_payload,
319                        size_t plen)
320 {
321         key_ref_t key_ref;
322         void *payload;
323         long ret;
324 
325         ret = -EINVAL;
326         if (plen > PAGE_SIZE)
327                 goto error;
328 
329         /* pull the payload in if one was supplied */
330         payload = NULL;
331         if (_payload) {
332                 ret = -ENOMEM;
333                 payload = kmalloc(plen, GFP_KERNEL);
334                 if (!payload)
335                         goto error;
336 
337                 ret = -EFAULT;
338                 if (copy_from_user(payload, _payload, plen) != 0)
339                         goto error2;
340         }
341 
342         /* find the target key (which must be writable) */
343         key_ref = lookup_user_key(id, 0, KEY_NEED_WRITE);
344         if (IS_ERR(key_ref)) {
345                 ret = PTR_ERR(key_ref);
346                 goto error2;
347         }
348 
349         /* update the key */
350         ret = key_update(key_ref, payload, plen);
351 
352         key_ref_put(key_ref);
353 error2:
354         kfree(payload);
355 error:
356         return ret;
357 }
358 
359 /*
360  * Revoke a key.
361  *
362  * The key must be grant the caller Write or Setattr permission for this to
363  * work.  The key type should give up its quota claim when revoked.  The key
364  * and any links to the key will be automatically garbage collected after a
365  * certain amount of time (/proc/sys/kernel/keys/gc_delay).
366  *
367  * If successful, 0 is returned.
368  */
369 long keyctl_revoke_key(key_serial_t id)
370 {
371         key_ref_t key_ref;
372         long ret;
373 
374         key_ref = lookup_user_key(id, 0, KEY_NEED_WRITE);
375         if (IS_ERR(key_ref)) {
376                 ret = PTR_ERR(key_ref);
377                 if (ret != -EACCES)
378                         goto error;
379                 key_ref = lookup_user_key(id, 0, KEY_NEED_SETATTR);
380                 if (IS_ERR(key_ref)) {
381                         ret = PTR_ERR(key_ref);
382                         goto error;
383                 }
384         }
385 
386         key_revoke(key_ref_to_ptr(key_ref));
387         ret = 0;
388 
389         key_ref_put(key_ref);
390 error:
391         return ret;
392 }
393 
394 /*
395  * Invalidate a key.
396  *
397  * The key must be grant the caller Invalidate permission for this to work.
398  * The key and any links to the key will be automatically garbage collected
399  * immediately.
400  *
401  * If successful, 0 is returned.
402  */
403 long keyctl_invalidate_key(key_serial_t id)
404 {
405         key_ref_t key_ref;
406         long ret;
407 
408         kenter("%d", id);
409 
410         key_ref = lookup_user_key(id, 0, KEY_NEED_SEARCH);
411         if (IS_ERR(key_ref)) {
412                 ret = PTR_ERR(key_ref);
413 
414                 /* Root is permitted to invalidate certain special keys */
415                 if (capable(CAP_SYS_ADMIN)) {
416                         key_ref = lookup_user_key(id, 0, 0);
417                         if (IS_ERR(key_ref))
418                                 goto error;
419                         if (test_bit(KEY_FLAG_ROOT_CAN_INVAL,
420                                      &key_ref_to_ptr(key_ref)->flags))
421                                 goto invalidate;
422                         goto error_put;
423                 }
424 
425                 goto error;
426         }
427 
428 invalidate:
429         key_invalidate(key_ref_to_ptr(key_ref));
430         ret = 0;
431 error_put:
432         key_ref_put(key_ref);
433 error:
434         kleave(" = %ld", ret);
435         return ret;
436 }
437 
438 /*
439  * Clear the specified keyring, creating an empty process keyring if one of the
440  * special keyring IDs is used.
441  *
442  * The keyring must grant the caller Write permission for this to work.  If
443  * successful, 0 will be returned.
444  */
445 long keyctl_keyring_clear(key_serial_t ringid)
446 {
447         key_ref_t keyring_ref;
448         long ret;
449 
450         keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
451         if (IS_ERR(keyring_ref)) {
452                 ret = PTR_ERR(keyring_ref);
453 
454                 /* Root is permitted to invalidate certain special keyrings */
455                 if (capable(CAP_SYS_ADMIN)) {
456                         keyring_ref = lookup_user_key(ringid, 0, 0);
457                         if (IS_ERR(keyring_ref))
458                                 goto error;
459                         if (test_bit(KEY_FLAG_ROOT_CAN_CLEAR,
460                                      &key_ref_to_ptr(keyring_ref)->flags))
461                                 goto clear;
462                         goto error_put;
463                 }
464 
465                 goto error;
466         }
467 
468 clear:
469         ret = keyring_clear(key_ref_to_ptr(keyring_ref));
470 error_put:
471         key_ref_put(keyring_ref);
472 error:
473         return ret;
474 }
475 
476 /*
477  * Create a link from a keyring to a key if there's no matching key in the
478  * keyring, otherwise replace the link to the matching key with a link to the
479  * new key.
480  *
481  * The key must grant the caller Link permission and the the keyring must grant
482  * the caller Write permission.  Furthermore, if an additional link is created,
483  * the keyring's quota will be extended.
484  *
485  * If successful, 0 will be returned.
486  */
487 long keyctl_keyring_link(key_serial_t id, key_serial_t ringid)
488 {
489         key_ref_t keyring_ref, key_ref;
490         long ret;
491 
492         keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
493         if (IS_ERR(keyring_ref)) {
494                 ret = PTR_ERR(keyring_ref);
495                 goto error;
496         }
497 
498         key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE, KEY_NEED_LINK);
499         if (IS_ERR(key_ref)) {
500                 ret = PTR_ERR(key_ref);
501                 goto error2;
502         }
503 
504         ret = key_link(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));
505 
506         key_ref_put(key_ref);
507 error2:
508         key_ref_put(keyring_ref);
509 error:
510         return ret;
511 }
512 
513 /*
514  * Unlink a key from a keyring.
515  *
516  * The keyring must grant the caller Write permission for this to work; the key
517  * itself need not grant the caller anything.  If the last link to a key is
518  * removed then that key will be scheduled for destruction.
519  *
520  * If successful, 0 will be returned.
521  */
522 long keyctl_keyring_unlink(key_serial_t id, key_serial_t ringid)
523 {
524         key_ref_t keyring_ref, key_ref;
525         long ret;
526 
527         keyring_ref = lookup_user_key(ringid, 0, KEY_NEED_WRITE);
528         if (IS_ERR(keyring_ref)) {
529                 ret = PTR_ERR(keyring_ref);
530                 goto error;
531         }
532 
533         key_ref = lookup_user_key(id, KEY_LOOKUP_FOR_UNLINK, 0);
534         if (IS_ERR(key_ref)) {
535                 ret = PTR_ERR(key_ref);
536                 goto error2;
537         }
538 
539         ret = key_unlink(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));
540 
541         key_ref_put(key_ref);
542 error2:
543         key_ref_put(keyring_ref);
544 error:
545         return ret;
546 }
547 
548 /*
549  * Return a description of a key to userspace.
550  *
551  * The key must grant the caller View permission for this to work.
552  *
553  * If there's a buffer, we place up to buflen bytes of data into it formatted
554  * in the following way:
555  *
556  *      type;uid;gid;perm;description<NUL>
557  *
558  * If successful, we return the amount of description available, irrespective
559  * of how much we may have copied into the buffer.
560  */
561 long keyctl_describe_key(key_serial_t keyid,
562                          char __user *buffer,
563                          size_t buflen)
564 {
565         struct key *key, *instkey;
566         key_ref_t key_ref;
567         char *infobuf;
568         long ret;
569         int desclen, infolen;
570 
571         key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_NEED_VIEW);
572         if (IS_ERR(key_ref)) {
573                 /* viewing a key under construction is permitted if we have the
574                  * authorisation token handy */
575                 if (PTR_ERR(key_ref) == -EACCES) {
576                         instkey = key_get_instantiation_authkey(keyid);
577                         if (!IS_ERR(instkey)) {
578                                 key_put(instkey);
579                                 key_ref = lookup_user_key(keyid,
580                                                           KEY_LOOKUP_PARTIAL,
581                                                           0);
582                                 if (!IS_ERR(key_ref))
583                                         goto okay;
584                         }
585                 }
586 
587                 ret = PTR_ERR(key_ref);
588                 goto error;
589         }
590 
591 okay:
592         key = key_ref_to_ptr(key_ref);
593         desclen = strlen(key->description);
594 
595         /* calculate how much information we're going to return */
596         ret = -ENOMEM;
597         infobuf = kasprintf(GFP_KERNEL,
598                             "%s;%d;%d;%08x;",
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         if (!infobuf)
604                 goto error2;
605         infolen = strlen(infobuf);
606         ret = infolen + desclen + 1;
607 
608         /* consider returning the data */
609         if (buffer && buflen >= ret) {
610                 if (copy_to_user(buffer, infobuf, infolen) != 0 ||
611                     copy_to_user(buffer + infolen, key->description,
612                                  desclen + 1) != 0)
613                         ret = -EFAULT;
614         }
615 
616         kfree(infobuf);
617 error2:
618         key_ref_put(key_ref);
619 error:
620         return ret;
621 }
622 
623 /*
624  * Search the specified keyring and any keyrings it links to for a matching
625  * key.  Only keyrings that grant the caller Search permission will be searched
626  * (this includes the starting keyring).  Only keys with Search permission can
627  * be found.
628  *
629  * If successful, the found key will be linked to the destination keyring if
630  * supplied and the key has Link permission, and the found key ID will be
631  * returned.
632  */
633 long keyctl_keyring_search(key_serial_t ringid,
634                            const char __user *_type,
635                            const char __user *_description,
636                            key_serial_t destringid)
637 {
638         struct key_type *ktype;
639         key_ref_t keyring_ref, key_ref, dest_ref;
640         char type[32], *description;
641         long ret;
642 
643         /* pull the type and description into kernel space */
644         ret = key_get_type_from_user(type, _type, sizeof(type));
645         if (ret < 0)
646                 goto error;
647 
648         description = strndup_user(_description, KEY_MAX_DESC_SIZE);
649         if (IS_ERR(description)) {
650                 ret = PTR_ERR(description);
651                 goto error;
652         }
653 
654         /* get the keyring at which to begin the search */
655         keyring_ref = lookup_user_key(ringid, 0, KEY_NEED_SEARCH);
656         if (IS_ERR(keyring_ref)) {
657                 ret = PTR_ERR(keyring_ref);
658                 goto error2;
659         }
660 
661         /* get the destination keyring if specified */
662         dest_ref = NULL;
663         if (destringid) {
664                 dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
665                                            KEY_NEED_WRITE);
666                 if (IS_ERR(dest_ref)) {
667                         ret = PTR_ERR(dest_ref);
668                         goto error3;
669                 }
670         }
671 
672         /* find the key type */
673         ktype = key_type_lookup(type);
674         if (IS_ERR(ktype)) {
675                 ret = PTR_ERR(ktype);
676                 goto error4;
677         }
678 
679         /* do the search */
680         key_ref = keyring_search(keyring_ref, ktype, description);
681         if (IS_ERR(key_ref)) {
682                 ret = PTR_ERR(key_ref);
683 
684                 /* treat lack or presence of a negative key the same */
685                 if (ret == -EAGAIN)
686                         ret = -ENOKEY;
687                 goto error5;
688         }
689 
690         /* link the resulting key to the destination keyring if we can */
691         if (dest_ref) {
692                 ret = key_permission(key_ref, KEY_NEED_LINK);
693                 if (ret < 0)
694                         goto error6;
695 
696                 ret = key_link(key_ref_to_ptr(dest_ref), key_ref_to_ptr(key_ref));
697                 if (ret < 0)
698                         goto error6;
699         }
700 
701         ret = key_ref_to_ptr(key_ref)->serial;
702 
703 error6:
704         key_ref_put(key_ref);
705 error5:
706         key_type_put(ktype);
707 error4:
708         key_ref_put(dest_ref);
709 error3:
710         key_ref_put(keyring_ref);
711 error2:
712         kfree(description);
713 error:
714         return ret;
715 }
716 
717 /*
718  * Read a key's payload.
719  *
720  * The key must either grant the caller Read permission, or it must grant the
721  * caller Search permission when searched for from the process keyrings.
722  *
723  * If successful, we place up to buflen bytes of data into the buffer, if one
724  * is provided, and return the amount of data that is available in the key,
725  * irrespective of how much we copied into the buffer.
726  */
727 long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen)
728 {
729         struct key *key;
730         key_ref_t key_ref;
731         long ret;
732 
733         /* find the key first */
734         key_ref = lookup_user_key(keyid, 0, 0);
735         if (IS_ERR(key_ref)) {
736                 ret = -ENOKEY;
737                 goto error;
738         }
739 
740         key = key_ref_to_ptr(key_ref);
741 
742         /* see if we can read it directly */
743         ret = key_permission(key_ref, KEY_NEED_READ);
744         if (ret == 0)
745                 goto can_read_key;
746         if (ret != -EACCES)
747                 goto error;
748 
749         /* we can't; see if it's searchable from this process's keyrings
750          * - we automatically take account of the fact that it may be
751          *   dangling off an instantiation key
752          */
753         if (!is_key_possessed(key_ref)) {
754                 ret = -EACCES;
755                 goto error2;
756         }
757 
758         /* the key is probably readable - now try to read it */
759 can_read_key:
760         ret = key_validate(key);
761         if (ret == 0) {
762                 ret = -EOPNOTSUPP;
763                 if (key->type->read) {
764                         /* read the data with the semaphore held (since we
765                          * might sleep) */
766                         down_read(&key->sem);
767                         ret = key->type->read(key, buffer, buflen);
768                         up_read(&key->sem);
769                 }
770         }
771 
772 error2:
773         key_put(key);
774 error:
775         return ret;
776 }
777 
778 /*
779  * Change the ownership of a key
780  *
781  * The key must grant the caller Setattr permission for this to work, though
782  * the key need not be fully instantiated yet.  For the UID to be changed, or
783  * for the GID to be changed to a group the caller is not a member of, the
784  * caller must have sysadmin capability.  If either uid or gid is -1 then that
785  * attribute is not changed.
786  *
787  * If the UID is to be changed, the new user must have sufficient quota to
788  * accept the key.  The quota deduction will be removed from the old user to
789  * the new user should the attribute be changed.
790  *
791  * If successful, 0 will be returned.
792  */
793 long keyctl_chown_key(key_serial_t id, uid_t user, gid_t group)
794 {
795         struct key_user *newowner, *zapowner = NULL;
796         struct key *key;
797         key_ref_t key_ref;
798         long ret;
799         kuid_t uid;
800         kgid_t gid;
801 
802         uid = make_kuid(current_user_ns(), user);
803         gid = make_kgid(current_user_ns(), group);
804         ret = -EINVAL;
805         if ((user != (uid_t) -1) && !uid_valid(uid))
806                 goto error;
807         if ((group != (gid_t) -1) && !gid_valid(gid))
808                 goto error;
809 
810         ret = 0;
811         if (user == (uid_t) -1 && group == (gid_t) -1)
812                 goto error;
813 
814         key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
815                                   KEY_NEED_SETATTR);
816         if (IS_ERR(key_ref)) {
817                 ret = PTR_ERR(key_ref);
818                 goto error;
819         }
820 
821         key = key_ref_to_ptr(key_ref);
822 
823         /* make the changes with the locks held to prevent chown/chown races */
824         ret = -EACCES;
825         down_write(&key->sem);
826 
827         if (!capable(CAP_SYS_ADMIN)) {
828                 /* only the sysadmin can chown a key to some other UID */
829                 if (user != (uid_t) -1 && !uid_eq(key->uid, uid))
830                         goto error_put;
831 
832                 /* only the sysadmin can set the key's GID to a group other
833                  * than one of those that the current process subscribes to */
834                 if (group != (gid_t) -1 && !gid_eq(gid, key->gid) && !in_group_p(gid))
835                         goto error_put;
836         }
837 
838         /* change the UID */
839         if (user != (uid_t) -1 && !uid_eq(uid, key->uid)) {
840                 ret = -ENOMEM;
841                 newowner = key_user_lookup(uid);
842                 if (!newowner)
843                         goto error_put;
844 
845                 /* transfer the quota burden to the new user */
846                 if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
847                         unsigned maxkeys = uid_eq(uid, GLOBAL_ROOT_UID) ?
848                                 key_quota_root_maxkeys : key_quota_maxkeys;
849                         unsigned maxbytes = uid_eq(uid, GLOBAL_ROOT_UID) ?
850                                 key_quota_root_maxbytes : key_quota_maxbytes;
851 
852                         spin_lock(&newowner->lock);
853                         if (newowner->qnkeys + 1 >= maxkeys ||
854                             newowner->qnbytes + key->quotalen >= maxbytes ||
855                             newowner->qnbytes + key->quotalen <
856                             newowner->qnbytes)
857                                 goto quota_overrun;
858 
859                         newowner->qnkeys++;
860                         newowner->qnbytes += key->quotalen;
861                         spin_unlock(&newowner->lock);
862 
863                         spin_lock(&key->user->lock);
864                         key->user->qnkeys--;
865                         key->user->qnbytes -= key->quotalen;
866                         spin_unlock(&key->user->lock);
867                 }
868 
869                 atomic_dec(&key->user->nkeys);
870                 atomic_inc(&newowner->nkeys);
871 
872                 if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
873                         atomic_dec(&key->user->nikeys);
874                         atomic_inc(&newowner->nikeys);
875                 }
876 
877                 zapowner = key->user;
878                 key->user = newowner;
879                 key->uid = uid;
880         }
881 
882         /* change the GID */
883         if (group != (gid_t) -1)
884                 key->gid = gid;
885 
886         ret = 0;
887 
888 error_put:
889         up_write(&key->sem);
890         key_put(key);
891         if (zapowner)
892                 key_user_put(zapowner);
893 error:
894         return ret;
895 
896 quota_overrun:
897         spin_unlock(&newowner->lock);
898         zapowner = newowner;
899         ret = -EDQUOT;
900         goto error_put;
901 }
902 
903 /*
904  * Change the permission mask on a key.
905  *
906  * The key must grant the caller Setattr permission for this to work, though
907  * the key need not be fully instantiated yet.  If the caller does not have
908  * sysadmin capability, it may only change the permission on keys that it owns.
909  */
910 long keyctl_setperm_key(key_serial_t id, key_perm_t perm)
911 {
912         struct key *key;
913         key_ref_t key_ref;
914         long ret;
915 
916         ret = -EINVAL;
917         if (perm & ~(KEY_POS_ALL | KEY_USR_ALL | KEY_GRP_ALL | KEY_OTH_ALL))
918                 goto error;
919 
920         key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
921                                   KEY_NEED_SETATTR);
922         if (IS_ERR(key_ref)) {
923                 ret = PTR_ERR(key_ref);
924                 goto error;
925         }
926 
927         key = key_ref_to_ptr(key_ref);
928 
929         /* make the changes with the locks held to prevent chown/chmod races */
930         ret = -EACCES;
931         down_write(&key->sem);
932 
933         /* if we're not the sysadmin, we can only change a key that we own */
934         if (capable(CAP_SYS_ADMIN) || uid_eq(key->uid, current_fsuid())) {
935                 key->perm = perm;
936                 ret = 0;
937         }
938 
939         up_write(&key->sem);
940         key_put(key);
941 error:
942         return ret;
943 }
944 
945 /*
946  * Get the destination keyring for instantiation and check that the caller has
947  * Write permission on it.
948  */
949 static long get_instantiation_keyring(key_serial_t ringid,
950                                       struct request_key_auth *rka,
951                                       struct key **_dest_keyring)
952 {
953         key_ref_t dkref;
954 
955         *_dest_keyring = NULL;
956 
957         /* just return a NULL pointer if we weren't asked to make a link */
958         if (ringid == 0)
959                 return 0;
960 
961         /* if a specific keyring is nominated by ID, then use that */
962         if (ringid > 0) {
963                 dkref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
964                 if (IS_ERR(dkref))
965                         return PTR_ERR(dkref);
966                 *_dest_keyring = key_ref_to_ptr(dkref);
967                 return 0;
968         }
969 
970         if (ringid == KEY_SPEC_REQKEY_AUTH_KEY)
971                 return -EINVAL;
972 
973         /* otherwise specify the destination keyring recorded in the
974          * authorisation key (any KEY_SPEC_*_KEYRING) */
975         if (ringid >= KEY_SPEC_REQUESTOR_KEYRING) {
976                 *_dest_keyring = key_get(rka->dest_keyring);
977                 return 0;
978         }
979 
980         return -ENOKEY;
981 }
982 
983 /*
984  * Change the request_key authorisation key on the current process.
985  */
986 static int keyctl_change_reqkey_auth(struct key *key)
987 {
988         struct cred *new;
989 
990         new = prepare_creds();
991         if (!new)
992                 return -ENOMEM;
993 
994         key_put(new->request_key_auth);
995         new->request_key_auth = key_get(key);
996 
997         return commit_creds(new);
998 }
999 
1000 /*
1001  * Copy the iovec data from userspace
1002  */
1003 static long copy_from_user_iovec(void *buffer, const struct iovec *iov,
1004                                  unsigned ioc)
1005 {
1006         for (; ioc > 0; ioc--) {
1007                 if (copy_from_user(buffer, iov->iov_base, iov->iov_len) != 0)
1008                         return -EFAULT;
1009                 buffer += iov->iov_len;
1010                 iov++;
1011         }
1012         return 0;
1013 }
1014 
1015 /*
1016  * Instantiate a key with the specified payload and link the key into the
1017  * destination keyring if one is given.
1018  *
1019  * The caller must have the appropriate instantiation permit set for this to
1020  * work (see keyctl_assume_authority).  No other permissions are required.
1021  *
1022  * If successful, 0 will be returned.
1023  */
1024 long keyctl_instantiate_key_common(key_serial_t id,
1025                                    const struct iovec *payload_iov,
1026                                    unsigned ioc,
1027                                    size_t plen,
1028                                    key_serial_t ringid)
1029 {
1030         const struct cred *cred = current_cred();
1031         struct request_key_auth *rka;
1032         struct key *instkey, *dest_keyring;
1033         void *payload;
1034         long ret;
1035         bool vm = false;
1036 
1037         kenter("%d,,%zu,%d", id, plen, ringid);
1038 
1039         ret = -EINVAL;
1040         if (plen > 1024 * 1024 - 1)
1041                 goto error;
1042 
1043         /* the appropriate instantiation authorisation key must have been
1044          * assumed before calling this */
1045         ret = -EPERM;
1046         instkey = cred->request_key_auth;
1047         if (!instkey)
1048                 goto error;
1049 
1050         rka = instkey->payload.data;
1051         if (rka->target_key->serial != id)
1052                 goto error;
1053 
1054         /* pull the payload in if one was supplied */
1055         payload = NULL;
1056 
1057         if (payload_iov) {
1058                 ret = -ENOMEM;
1059                 payload = kmalloc(plen, GFP_KERNEL);
1060                 if (!payload) {
1061                         if (plen <= PAGE_SIZE)
1062                                 goto error;
1063                         vm = true;
1064                         payload = vmalloc(plen);
1065                         if (!payload)
1066                                 goto error;
1067                 }
1068 
1069                 ret = copy_from_user_iovec(payload, payload_iov, ioc);
1070                 if (ret < 0)
1071                         goto error2;
1072         }
1073 
1074         /* find the destination keyring amongst those belonging to the
1075          * requesting task */
1076         ret = get_instantiation_keyring(ringid, rka, &dest_keyring);
1077         if (ret < 0)
1078                 goto error2;
1079 
1080         /* instantiate the key and link it into a keyring */
1081         ret = key_instantiate_and_link(rka->target_key, payload, plen,
1082                                        dest_keyring, instkey);
1083 
1084         key_put(dest_keyring);
1085 
1086         /* discard the assumed authority if it's just been disabled by
1087          * instantiation of the key */
1088         if (ret == 0)
1089                 keyctl_change_reqkey_auth(NULL);
1090 
1091 error2:
1092         if (!vm)
1093                 kfree(payload);
1094         else
1095                 vfree(payload);
1096 error:
1097         return ret;
1098 }
1099 
1100 /*
1101  * Instantiate a key with the specified payload and link the key into the
1102  * destination keyring if one is given.
1103  *
1104  * The caller must have the appropriate instantiation permit set for this to
1105  * work (see keyctl_assume_authority).  No other permissions are required.
1106  *
1107  * If successful, 0 will be returned.
1108  */
1109 long keyctl_instantiate_key(key_serial_t id,
1110                             const void __user *_payload,
1111                             size_t plen,
1112                             key_serial_t ringid)
1113 {
1114         if (_payload && plen) {
1115                 struct iovec iov[1] = {
1116                         [0].iov_base = (void __user *)_payload,
1117                         [0].iov_len  = plen
1118                 };
1119 
1120                 return keyctl_instantiate_key_common(id, iov, 1, plen, ringid);
1121         }
1122 
1123         return keyctl_instantiate_key_common(id, NULL, 0, 0, ringid);
1124 }
1125 
1126 /*
1127  * Instantiate a key with the specified multipart payload and link the key into
1128  * the destination keyring if one is given.
1129  *
1130  * The caller must have the appropriate instantiation permit set for this to
1131  * work (see keyctl_assume_authority).  No other permissions are required.
1132  *
1133  * If successful, 0 will be returned.
1134  */
1135 long keyctl_instantiate_key_iov(key_serial_t id,
1136                                 const struct iovec __user *_payload_iov,
1137                                 unsigned ioc,
1138                                 key_serial_t ringid)
1139 {
1140         struct iovec iovstack[UIO_FASTIOV], *iov = iovstack;
1141         long ret;
1142 
1143         if (!_payload_iov || !ioc)
1144                 goto no_payload;
1145 
1146         ret = rw_copy_check_uvector(WRITE, _payload_iov, ioc,
1147                                     ARRAY_SIZE(iovstack), iovstack, &iov);
1148         if (ret < 0)
1149                 goto err;
1150         if (ret == 0)
1151                 goto no_payload_free;
1152 
1153         ret = keyctl_instantiate_key_common(id, iov, ioc, ret, ringid);
1154 err:
1155         if (iov != iovstack)
1156                 kfree(iov);
1157         return ret;
1158 
1159 no_payload_free:
1160         if (iov != iovstack)
1161                 kfree(iov);
1162 no_payload:
1163         return keyctl_instantiate_key_common(id, NULL, 0, 0, ringid);
1164 }
1165 
1166 /*
1167  * Negatively instantiate the key with the given timeout (in seconds) and link
1168  * the key into the destination keyring if one is given.
1169  *
1170  * The caller must have the appropriate instantiation permit set for this to
1171  * work (see keyctl_assume_authority).  No other permissions are required.
1172  *
1173  * The key and any links to the key will be automatically garbage collected
1174  * after the timeout expires.
1175  *
1176  * Negative keys are used to rate limit repeated request_key() calls by causing
1177  * them to return -ENOKEY until the negative key expires.
1178  *
1179  * If successful, 0 will be returned.
1180  */
1181 long keyctl_negate_key(key_serial_t id, unsigned timeout, key_serial_t ringid)
1182 {
1183         return keyctl_reject_key(id, timeout, ENOKEY, ringid);
1184 }
1185 
1186 /*
1187  * Negatively instantiate the key with the given timeout (in seconds) and error
1188  * code and link the key into the destination keyring if one is given.
1189  *
1190  * The caller must have the appropriate instantiation permit set for this to
1191  * work (see keyctl_assume_authority).  No other permissions are required.
1192  *
1193  * The key and any links to the key will be automatically garbage collected
1194  * after the timeout expires.
1195  *
1196  * Negative keys are used to rate limit repeated request_key() calls by causing
1197  * them to return the specified error code until the negative key expires.
1198  *
1199  * If successful, 0 will be returned.
1200  */
1201 long keyctl_reject_key(key_serial_t id, unsigned timeout, unsigned error,
1202                        key_serial_t ringid)
1203 {
1204         const struct cred *cred = current_cred();
1205         struct request_key_auth *rka;
1206         struct key *instkey, *dest_keyring;
1207         long ret;
1208 
1209         kenter("%d,%u,%u,%d", id, timeout, error, ringid);
1210 
1211         /* must be a valid error code and mustn't be a kernel special */
1212         if (error <= 0 ||
1213             error >= MAX_ERRNO ||
1214             error == ERESTARTSYS ||
1215             error == ERESTARTNOINTR ||
1216             error == ERESTARTNOHAND ||
1217             error == ERESTART_RESTARTBLOCK)
1218                 return -EINVAL;
1219 
1220         /* the appropriate instantiation authorisation key must have been
1221          * assumed before calling this */
1222         ret = -EPERM;
1223         instkey = cred->request_key_auth;
1224         if (!instkey)
1225                 goto error;
1226 
1227         rka = instkey->payload.data;
1228         if (rka->target_key->serial != id)
1229                 goto error;
1230 
1231         /* find the destination keyring if present (which must also be
1232          * writable) */
1233         ret = get_instantiation_keyring(ringid, rka, &dest_keyring);
1234         if (ret < 0)
1235                 goto error;
1236 
1237         /* instantiate the key and link it into a keyring */
1238         ret = key_reject_and_link(rka->target_key, timeout, error,
1239                                   dest_keyring, instkey);
1240 
1241         key_put(dest_keyring);
1242 
1243         /* discard the assumed authority if it's just been disabled by
1244          * instantiation of the key */
1245         if (ret == 0)
1246                 keyctl_change_reqkey_auth(NULL);
1247 
1248 error:
1249         return ret;
1250 }
1251 
1252 /*
1253  * Read or set the default keyring in which request_key() will cache keys and
1254  * return the old setting.
1255  *
1256  * If a process keyring is specified then this will be created if it doesn't
1257  * yet exist.  The old setting will be returned if successful.
1258  */
1259 long keyctl_set_reqkey_keyring(int reqkey_defl)
1260 {
1261         struct cred *new;
1262         int ret, old_setting;
1263 
1264         old_setting = current_cred_xxx(jit_keyring);
1265 
1266         if (reqkey_defl == KEY_REQKEY_DEFL_NO_CHANGE)
1267                 return old_setting;
1268 
1269         new = prepare_creds();
1270         if (!new)
1271                 return -ENOMEM;
1272 
1273         switch (reqkey_defl) {
1274         case KEY_REQKEY_DEFL_THREAD_KEYRING:
1275                 ret = install_thread_keyring_to_cred(new);
1276                 if (ret < 0)
1277                         goto error;
1278                 goto set;
1279 
1280         case KEY_REQKEY_DEFL_PROCESS_KEYRING:
1281                 ret = install_process_keyring_to_cred(new);
1282                 if (ret < 0) {
1283                         if (ret != -EEXIST)
1284                                 goto error;
1285                         ret = 0;
1286                 }
1287                 goto set;
1288 
1289         case KEY_REQKEY_DEFL_DEFAULT:
1290         case KEY_REQKEY_DEFL_SESSION_KEYRING:
1291         case KEY_REQKEY_DEFL_USER_KEYRING:
1292         case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
1293         case KEY_REQKEY_DEFL_REQUESTOR_KEYRING:
1294                 goto set;
1295 
1296         case KEY_REQKEY_DEFL_NO_CHANGE:
1297         case KEY_REQKEY_DEFL_GROUP_KEYRING:
1298         default:
1299                 ret = -EINVAL;
1300                 goto error;
1301         }
1302 
1303 set:
1304         new->jit_keyring = reqkey_defl;
1305         commit_creds(new);
1306         return old_setting;
1307 error:
1308         abort_creds(new);
1309         return ret;
1310 }
1311 
1312 /*
1313  * Set or clear the timeout on a key.
1314  *
1315  * Either the key must grant the caller Setattr permission or else the caller
1316  * must hold an instantiation authorisation token for the key.
1317  *
1318  * The timeout is either 0 to clear the timeout, or a number of seconds from
1319  * the current time.  The key and any links to the key will be automatically
1320  * garbage collected after the timeout expires.
1321  *
1322  * If successful, 0 is returned.
1323  */
1324 long keyctl_set_timeout(key_serial_t id, unsigned timeout)
1325 {
1326         struct key *key, *instkey;
1327         key_ref_t key_ref;
1328         long ret;
1329 
1330         key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
1331                                   KEY_NEED_SETATTR);
1332         if (IS_ERR(key_ref)) {
1333                 /* setting the timeout on a key under construction is permitted
1334                  * if we have the authorisation token handy */
1335                 if (PTR_ERR(key_ref) == -EACCES) {
1336                         instkey = key_get_instantiation_authkey(id);
1337                         if (!IS_ERR(instkey)) {
1338                                 key_put(instkey);
1339                                 key_ref = lookup_user_key(id,
1340                                                           KEY_LOOKUP_PARTIAL,
1341                                                           0);
1342                                 if (!IS_ERR(key_ref))
1343                                         goto okay;
1344                         }
1345                 }
1346 
1347                 ret = PTR_ERR(key_ref);
1348                 goto error;
1349         }
1350 
1351 okay:
1352         key = key_ref_to_ptr(key_ref);
1353         key_set_timeout(key, timeout);
1354         key_put(key);
1355 
1356         ret = 0;
1357 error:
1358         return ret;
1359 }
1360 
1361 /*
1362  * Assume (or clear) the authority to instantiate the specified key.
1363  *
1364  * This sets the authoritative token currently in force for key instantiation.
1365  * This must be done for a key to be instantiated.  It has the effect of making
1366  * available all the keys from the caller of the request_key() that created a
1367  * key to request_key() calls made by the caller of this function.
1368  *
1369  * The caller must have the instantiation key in their process keyrings with a
1370  * Search permission grant available to the caller.
1371  *
1372  * If the ID given is 0, then the setting will be cleared and 0 returned.
1373  *
1374  * If the ID given has a matching an authorisation key, then that key will be
1375  * set and its ID will be returned.  The authorisation key can be read to get
1376  * the callout information passed to request_key().
1377  */
1378 long keyctl_assume_authority(key_serial_t id)
1379 {
1380         struct key *authkey;
1381         long ret;
1382 
1383         /* special key IDs aren't permitted */
1384         ret = -EINVAL;
1385         if (id < 0)
1386                 goto error;
1387 
1388         /* we divest ourselves of authority if given an ID of 0 */
1389         if (id == 0) {
1390                 ret = keyctl_change_reqkey_auth(NULL);
1391                 goto error;
1392         }
1393 
1394         /* attempt to assume the authority temporarily granted to us whilst we
1395          * instantiate the specified key
1396          * - the authorisation key must be in the current task's keyrings
1397          *   somewhere
1398          */
1399         authkey = key_get_instantiation_authkey(id);
1400         if (IS_ERR(authkey)) {
1401                 ret = PTR_ERR(authkey);
1402                 goto error;
1403         }
1404 
1405         ret = keyctl_change_reqkey_auth(authkey);
1406         if (ret < 0)
1407                 goto error;
1408         key_put(authkey);
1409 
1410         ret = authkey->serial;
1411 error:
1412         return ret;
1413 }
1414 
1415 /*
1416  * Get a key's the LSM security label.
1417  *
1418  * The key must grant the caller View permission for this to work.
1419  *
1420  * If there's a buffer, then up to buflen bytes of data will be placed into it.
1421  *
1422  * If successful, the amount of information available will be returned,
1423  * irrespective of how much was copied (including the terminal NUL).
1424  */
1425 long keyctl_get_security(key_serial_t keyid,
1426                          char __user *buffer,
1427                          size_t buflen)
1428 {
1429         struct key *key, *instkey;
1430         key_ref_t key_ref;
1431         char *context;
1432         long ret;
1433 
1434         key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_NEED_VIEW);
1435         if (IS_ERR(key_ref)) {
1436                 if (PTR_ERR(key_ref) != -EACCES)
1437                         return PTR_ERR(key_ref);
1438 
1439                 /* viewing a key under construction is also permitted if we
1440                  * have the authorisation token handy */
1441                 instkey = key_get_instantiation_authkey(keyid);
1442                 if (IS_ERR(instkey))
1443                         return PTR_ERR(instkey);
1444                 key_put(instkey);
1445 
1446                 key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, 0);
1447                 if (IS_ERR(key_ref))
1448                         return PTR_ERR(key_ref);
1449         }
1450 
1451         key = key_ref_to_ptr(key_ref);
1452         ret = security_key_getsecurity(key, &context);
1453         if (ret == 0) {
1454                 /* if no information was returned, give userspace an empty
1455                  * string */
1456                 ret = 1;
1457                 if (buffer && buflen > 0 &&
1458                     copy_to_user(buffer, "", 1) != 0)
1459                         ret = -EFAULT;
1460         } else if (ret > 0) {
1461                 /* return as much data as there's room for */
1462                 if (buffer && buflen > 0) {
1463                         if (buflen > ret)
1464                                 buflen = ret;
1465 
1466                         if (copy_to_user(buffer, context, buflen) != 0)
1467                                 ret = -EFAULT;
1468                 }
1469 
1470                 kfree(context);
1471         }
1472 
1473         key_ref_put(key_ref);
1474         return ret;
1475 }
1476 
1477 /*
1478  * Attempt to install the calling process's session keyring on the process's
1479  * parent process.
1480  *
1481  * The keyring must exist and must grant the caller LINK permission, and the
1482  * parent process must be single-threaded and must have the same effective
1483  * ownership as this process and mustn't be SUID/SGID.
1484  *
1485  * The keyring will be emplaced on the parent when it next resumes userspace.
1486  *
1487  * If successful, 0 will be returned.
1488  */
1489 long keyctl_session_to_parent(void)
1490 {
1491         struct task_struct *me, *parent;
1492         const struct cred *mycred, *pcred;
1493         struct callback_head *newwork, *oldwork;
1494         key_ref_t keyring_r;
1495         struct cred *cred;
1496         int ret;
1497 
1498         keyring_r = lookup_user_key(KEY_SPEC_SESSION_KEYRING, 0, KEY_NEED_LINK);
1499         if (IS_ERR(keyring_r))
1500                 return PTR_ERR(keyring_r);
1501 
1502         ret = -ENOMEM;
1503 
1504         /* our parent is going to need a new cred struct, a new tgcred struct
1505          * and new security data, so we allocate them here to prevent ENOMEM in
1506          * our parent */
1507         cred = cred_alloc_blank();
1508         if (!cred)
1509                 goto error_keyring;
1510         newwork = &cred->rcu;
1511 
1512         cred->session_keyring = key_ref_to_ptr(keyring_r);
1513         keyring_r = NULL;
1514         init_task_work(newwork, key_change_session_keyring);
1515 
1516         me = current;
1517         rcu_read_lock();
1518         write_lock_irq(&tasklist_lock);
1519 
1520         ret = -EPERM;
1521         oldwork = NULL;
1522         parent = me->real_parent;
1523 
1524         /* the parent mustn't be init and mustn't be a kernel thread */
1525         if (parent->pid <= 1 || !parent->mm)
1526                 goto unlock;
1527 
1528         /* the parent must be single threaded */
1529         if (!thread_group_empty(parent))
1530                 goto unlock;
1531 
1532         /* the parent and the child must have different session keyrings or
1533          * there's no point */
1534         mycred = current_cred();
1535         pcred = __task_cred(parent);
1536         if (mycred == pcred ||
1537             mycred->session_keyring == pcred->session_keyring) {
1538                 ret = 0;
1539                 goto unlock;
1540         }
1541 
1542         /* the parent must have the same effective ownership and mustn't be
1543          * SUID/SGID */
1544         if (!uid_eq(pcred->uid,  mycred->euid) ||
1545             !uid_eq(pcred->euid, mycred->euid) ||
1546             !uid_eq(pcred->suid, mycred->euid) ||
1547             !gid_eq(pcred->gid,  mycred->egid) ||
1548             !gid_eq(pcred->egid, mycred->egid) ||
1549             !gid_eq(pcred->sgid, mycred->egid))
1550                 goto unlock;
1551 
1552         /* the keyrings must have the same UID */
1553         if ((pcred->session_keyring &&
1554              !uid_eq(pcred->session_keyring->uid, mycred->euid)) ||
1555             !uid_eq(mycred->session_keyring->uid, mycred->euid))
1556                 goto unlock;
1557 
1558         /* cancel an already pending keyring replacement */
1559         oldwork = task_work_cancel(parent, key_change_session_keyring);
1560 
1561         /* the replacement session keyring is applied just prior to userspace
1562          * restarting */
1563         ret = task_work_add(parent, newwork, true);
1564         if (!ret)
1565                 newwork = NULL;
1566 unlock:
1567         write_unlock_irq(&tasklist_lock);
1568         rcu_read_unlock();
1569         if (oldwork)
1570                 put_cred(container_of(oldwork, struct cred, rcu));
1571         if (newwork)
1572                 put_cred(cred);
1573         return ret;
1574 
1575 error_keyring:
1576         key_ref_put(keyring_r);
1577         return ret;
1578 }
1579 
1580 /*
1581  * The key control system call
1582  */
1583 SYSCALL_DEFINE5(keyctl, int, option, unsigned long, arg2, unsigned long, arg3,
1584                 unsigned long, arg4, unsigned long, arg5)
1585 {
1586         switch (option) {
1587         case KEYCTL_GET_KEYRING_ID:
1588                 return keyctl_get_keyring_ID((key_serial_t) arg2,
1589                                              (int) arg3);
1590 
1591         case KEYCTL_JOIN_SESSION_KEYRING:
1592                 return keyctl_join_session_keyring((const char __user *) arg2);
1593 
1594         case KEYCTL_UPDATE:
1595                 return keyctl_update_key((key_serial_t) arg2,
1596                                          (const void __user *) arg3,
1597                                          (size_t) arg4);
1598 
1599         case KEYCTL_REVOKE:
1600                 return keyctl_revoke_key((key_serial_t) arg2);
1601 
1602         case KEYCTL_DESCRIBE:
1603                 return keyctl_describe_key((key_serial_t) arg2,
1604                                            (char __user *) arg3,
1605                                            (unsigned) arg4);
1606 
1607         case KEYCTL_CLEAR:
1608                 return keyctl_keyring_clear((key_serial_t) arg2);
1609 
1610         case KEYCTL_LINK:
1611                 return keyctl_keyring_link((key_serial_t) arg2,
1612                                            (key_serial_t) arg3);
1613 
1614         case KEYCTL_UNLINK:
1615                 return keyctl_keyring_unlink((key_serial_t) arg2,
1616                                              (key_serial_t) arg3);
1617 
1618         case KEYCTL_SEARCH:
1619                 return keyctl_keyring_search((key_serial_t) arg2,
1620                                              (const char __user *) arg3,
1621                                              (const char __user *) arg4,
1622                                              (key_serial_t) arg5);
1623 
1624         case KEYCTL_READ:
1625                 return keyctl_read_key((key_serial_t) arg2,
1626                                        (char __user *) arg3,
1627                                        (size_t) arg4);
1628 
1629         case KEYCTL_CHOWN:
1630                 return keyctl_chown_key((key_serial_t) arg2,
1631                                         (uid_t) arg3,
1632                                         (gid_t) arg4);
1633 
1634         case KEYCTL_SETPERM:
1635                 return keyctl_setperm_key((key_serial_t) arg2,
1636                                           (key_perm_t) arg3);
1637 
1638         case KEYCTL_INSTANTIATE:
1639                 return keyctl_instantiate_key((key_serial_t) arg2,
1640                                               (const void __user *) arg3,
1641                                               (size_t) arg4,
1642                                               (key_serial_t) arg5);
1643 
1644         case KEYCTL_NEGATE:
1645                 return keyctl_negate_key((key_serial_t) arg2,
1646                                          (unsigned) arg3,
1647                                          (key_serial_t) arg4);
1648 
1649         case KEYCTL_SET_REQKEY_KEYRING:
1650                 return keyctl_set_reqkey_keyring(arg2);
1651 
1652         case KEYCTL_SET_TIMEOUT:
1653                 return keyctl_set_timeout((key_serial_t) arg2,
1654                                           (unsigned) arg3);
1655 
1656         case KEYCTL_ASSUME_AUTHORITY:
1657                 return keyctl_assume_authority((key_serial_t) arg2);
1658 
1659         case KEYCTL_GET_SECURITY:
1660                 return keyctl_get_security((key_serial_t) arg2,
1661                                            (char __user *) arg3,
1662                                            (size_t) arg4);
1663 
1664         case KEYCTL_SESSION_TO_PARENT:
1665                 return keyctl_session_to_parent();
1666 
1667         case KEYCTL_REJECT:
1668                 return keyctl_reject_key((key_serial_t) arg2,
1669                                          (unsigned) arg3,
1670                                          (unsigned) arg4,
1671                                          (key_serial_t) arg5);
1672 
1673         case KEYCTL_INSTANTIATE_IOV:
1674                 return keyctl_instantiate_key_iov(
1675                         (key_serial_t) arg2,
1676                         (const struct iovec __user *) arg3,
1677                         (unsigned) arg4,
1678                         (key_serial_t) arg5);
1679 
1680         case KEYCTL_INVALIDATE:
1681                 return keyctl_invalidate_key((key_serial_t) arg2);
1682 
1683         case KEYCTL_GET_PERSISTENT:
1684                 return keyctl_get_persistent((uid_t)arg2, (key_serial_t)arg3);
1685 
1686         default:
1687                 return -EOPNOTSUPP;
1688         }
1689 }
1690 

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