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1/*
2 * AppArmor security module
3 *
4 * This file contains AppArmor functions for unpacking policy loaded from
5 * userspace.
6 *
7 * Copyright (C) 1998-2008 Novell/SUSE
8 * Copyright 2009-2010 Canonical Ltd.
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License as
12 * published by the Free Software Foundation, version 2 of the
13 * License.
14 *
15 * AppArmor uses a serialized binary format for loading policy. To find
16 * policy format documentation look in Documentation/security/apparmor.txt
17 * All policy is validated before it is used.
18 */
19
20#include <asm/unaligned.h>
21#include <linux/ctype.h>
22#include <linux/errno.h>
23
24#include "include/apparmor.h"
25#include "include/audit.h"
26#include "include/context.h"
27#include "include/match.h"
28#include "include/policy.h"
29#include "include/policy_unpack.h"
30#include "include/sid.h"
31
32/*
33 * The AppArmor interface treats data as a type byte followed by the
34 * actual data. The interface has the notion of a a named entry
35 * which has a name (AA_NAME typecode followed by name string) followed by
36 * the entries typecode and data. Named types allow for optional
37 * elements and extensions to be added and tested for without breaking
38 * backwards compatibility.
39 */
40
41enum aa_code {
42 AA_U8,
43 AA_U16,
44 AA_U32,
45 AA_U64,
46 AA_NAME, /* same as string except it is items name */
47 AA_STRING,
48 AA_BLOB,
49 AA_STRUCT,
50 AA_STRUCTEND,
51 AA_LIST,
52 AA_LISTEND,
53 AA_ARRAY,
54 AA_ARRAYEND,
55};
56
57/*
58 * aa_ext is the read of the buffer containing the serialized profile. The
59 * data is copied into a kernel buffer in apparmorfs and then handed off to
60 * the unpack routines.
61 */
62struct aa_ext {
63 void *start;
64 void *end;
65 void *pos; /* pointer to current position in the buffer */
66 u32 version;
67};
68
69/* audit callback for unpack fields */
70static void audit_cb(struct audit_buffer *ab, void *va)
71{
72 struct common_audit_data *sa = va;
73 if (sa->aad->iface.target) {
74 struct aa_profile *name = sa->aad->iface.target;
75 audit_log_format(ab, " name=");
76 audit_log_untrustedstring(ab, name->base.hname);
77 }
78 if (sa->aad->iface.pos)
79 audit_log_format(ab, " offset=%ld", sa->aad->iface.pos);
80}
81
82/**
83 * audit_iface - do audit message for policy unpacking/load/replace/remove
84 * @new: profile if it has been allocated (MAYBE NULL)
85 * @name: name of the profile being manipulated (MAYBE NULL)
86 * @info: any extra info about the failure (MAYBE NULL)
87 * @e: buffer position info
88 * @error: error code
89 *
90 * Returns: %0 or error
91 */
92static int audit_iface(struct aa_profile *new, const char *name,
93 const char *info, struct aa_ext *e, int error)
94{
95 struct aa_profile *profile = __aa_current_profile();
96 struct common_audit_data sa;
97 struct apparmor_audit_data aad = {0,};
98 sa.type = LSM_AUDIT_DATA_NONE;
99 sa.aad = &aad;
100 if (e)
101 aad.iface.pos = e->pos - e->start;
102 aad.iface.target = new;
103 aad.name = name;
104 aad.info = info;
105 aad.error = error;
106
107 return aa_audit(AUDIT_APPARMOR_STATUS, profile, GFP_KERNEL, &sa,
108 audit_cb);
109}
110
111/* test if read will be in packed data bounds */
112static bool inbounds(struct aa_ext *e, size_t size)
113{
114 return (size <= e->end - e->pos);
115}
116
117/**
118 * aa_u16_chunck - test and do bounds checking for a u16 size based chunk
119 * @e: serialized data read head (NOT NULL)
120 * @chunk: start address for chunk of data (NOT NULL)
121 *
122 * Returns: the size of chunk found with the read head at the end of the chunk.
123 */
124static size_t unpack_u16_chunk(struct aa_ext *e, char **chunk)
125{
126 size_t size = 0;
127
128 if (!inbounds(e, sizeof(u16)))
129 return 0;
130 size = le16_to_cpu(get_unaligned((u16 *) e->pos));
131 e->pos += sizeof(u16);
132 if (!inbounds(e, size))
133 return 0;
134 *chunk = e->pos;
135 e->pos += size;
136 return size;
137}
138
139/* unpack control byte */
140static bool unpack_X(struct aa_ext *e, enum aa_code code)
141{
142 if (!inbounds(e, 1))
143 return 0;
144 if (*(u8 *) e->pos != code)
145 return 0;
146 e->pos++;
147 return 1;
148}
149
150/**
151 * unpack_nameX - check is the next element is of type X with a name of @name
152 * @e: serialized data extent information (NOT NULL)
153 * @code: type code
154 * @name: name to match to the serialized element. (MAYBE NULL)
155 *
156 * check that the next serialized data element is of type X and has a tag
157 * name @name. If @name is specified then there must be a matching
158 * name element in the stream. If @name is NULL any name element will be
159 * skipped and only the typecode will be tested.
160 *
161 * Returns 1 on success (both type code and name tests match) and the read
162 * head is advanced past the headers
163 *
164 * Returns: 0 if either match fails, the read head does not move
165 */
166static bool unpack_nameX(struct aa_ext *e, enum aa_code code, const char *name)
167{
168 /*
169 * May need to reset pos if name or type doesn't match
170 */
171 void *pos = e->pos;
172 /*
173 * Check for presence of a tagname, and if present name size
174 * AA_NAME tag value is a u16.
175 */
176 if (unpack_X(e, AA_NAME)) {
177 char *tag = NULL;
178 size_t size = unpack_u16_chunk(e, &tag);
179 /* if a name is specified it must match. otherwise skip tag */
180 if (name && (!size || strcmp(name, tag)))
181 goto fail;
182 } else if (name) {
183 /* if a name is specified and there is no name tag fail */
184 goto fail;
185 }
186
187 /* now check if type code matches */
188 if (unpack_X(e, code))
189 return 1;
190
191fail:
192 e->pos = pos;
193 return 0;
194}
195
196static bool unpack_u32(struct aa_ext *e, u32 *data, const char *name)
197{
198 if (unpack_nameX(e, AA_U32, name)) {
199 if (!inbounds(e, sizeof(u32)))
200 return 0;
201 if (data)
202 *data = le32_to_cpu(get_unaligned((u32 *) e->pos));
203 e->pos += sizeof(u32);
204 return 1;
205 }
206 return 0;
207}
208
209static bool unpack_u64(struct aa_ext *e, u64 *data, const char *name)
210{
211 if (unpack_nameX(e, AA_U64, name)) {
212 if (!inbounds(e, sizeof(u64)))
213 return 0;
214 if (data)
215 *data = le64_to_cpu(get_unaligned((u64 *) e->pos));
216 e->pos += sizeof(u64);
217 return 1;
218 }
219 return 0;
220}
221
222static size_t unpack_array(struct aa_ext *e, const char *name)
223{
224 if (unpack_nameX(e, AA_ARRAY, name)) {
225 int size;
226 if (!inbounds(e, sizeof(u16)))
227 return 0;
228 size = (int)le16_to_cpu(get_unaligned((u16 *) e->pos));
229 e->pos += sizeof(u16);
230 return size;
231 }
232 return 0;
233}
234
235static size_t unpack_blob(struct aa_ext *e, char **blob, const char *name)
236{
237 if (unpack_nameX(e, AA_BLOB, name)) {
238 u32 size;
239 if (!inbounds(e, sizeof(u32)))
240 return 0;
241 size = le32_to_cpu(get_unaligned((u32 *) e->pos));
242 e->pos += sizeof(u32);
243 if (inbounds(e, (size_t) size)) {
244 *blob = e->pos;
245 e->pos += size;
246 return size;
247 }
248 }
249 return 0;
250}
251
252static int unpack_str(struct aa_ext *e, const char **string, const char *name)
253{
254 char *src_str;
255 size_t size = 0;
256 void *pos = e->pos;
257 *string = NULL;
258 if (unpack_nameX(e, AA_STRING, name)) {
259 size = unpack_u16_chunk(e, &src_str);
260 if (size) {
261 /* strings are null terminated, length is size - 1 */
262 if (src_str[size - 1] != 0)
263 goto fail;
264 *string = src_str;
265 }
266 }
267 return size;
268
269fail:
270 e->pos = pos;
271 return 0;
272}
273
274static int unpack_strdup(struct aa_ext *e, char **string, const char *name)
275{
276 const char *tmp;
277 void *pos = e->pos;
278 int res = unpack_str(e, &tmp, name);
279 *string = NULL;
280
281 if (!res)
282 return 0;
283
284 *string = kmemdup(tmp, res, GFP_KERNEL);
285 if (!*string) {
286 e->pos = pos;
287 return 0;
288 }
289
290 return res;
291}
292
293/**
294 * verify_accept - verify the accept tables of a dfa
295 * @dfa: dfa to verify accept tables of (NOT NULL)
296 * @flags: flags governing dfa
297 *
298 * Returns: 1 if valid accept tables else 0 if error
299 */
300static bool verify_accept(struct aa_dfa *dfa, int flags)
301{
302 int i;
303
304 /* verify accept permissions */
305 for (i = 0; i < dfa->tables[YYTD_ID_ACCEPT]->td_lolen; i++) {
306 int mode = ACCEPT_TABLE(dfa)[i];
307
308 if (mode & ~DFA_VALID_PERM_MASK)
309 return 0;
310
311 if (ACCEPT_TABLE2(dfa)[i] & ~DFA_VALID_PERM2_MASK)
312 return 0;
313 }
314 return 1;
315}
316
317/**
318 * unpack_dfa - unpack a file rule dfa
319 * @e: serialized data extent information (NOT NULL)
320 *
321 * returns dfa or ERR_PTR or NULL if no dfa
322 */
323static struct aa_dfa *unpack_dfa(struct aa_ext *e)
324{
325 char *blob = NULL;
326 size_t size;
327 struct aa_dfa *dfa = NULL;
328
329 size = unpack_blob(e, &blob, "aadfa");
330 if (size) {
331 /*
332 * The dfa is aligned with in the blob to 8 bytes
333 * from the beginning of the stream.
334 */
335 size_t sz = blob - (char *)e->start;
336 size_t pad = ALIGN(sz, 8) - sz;
337 int flags = TO_ACCEPT1_FLAG(YYTD_DATA32) |
338 TO_ACCEPT2_FLAG(YYTD_DATA32);
339
340
341 if (aa_g_paranoid_load)
342 flags |= DFA_FLAG_VERIFY_STATES;
343
344 dfa = aa_dfa_unpack(blob + pad, size - pad, flags);
345
346 if (IS_ERR(dfa))
347 return dfa;
348
349 if (!verify_accept(dfa, flags))
350 goto fail;
351 }
352
353 return dfa;
354
355fail:
356 aa_put_dfa(dfa);
357 return ERR_PTR(-EPROTO);
358}
359
360/**
361 * unpack_trans_table - unpack a profile transition table
362 * @e: serialized data extent information (NOT NULL)
363 * @profile: profile to add the accept table to (NOT NULL)
364 *
365 * Returns: 1 if table successfully unpacked
366 */
367static bool unpack_trans_table(struct aa_ext *e, struct aa_profile *profile)
368{
369 void *pos = e->pos;
370
371 /* exec table is optional */
372 if (unpack_nameX(e, AA_STRUCT, "xtable")) {
373 int i, size;
374
375 size = unpack_array(e, NULL);
376 /* currently 4 exec bits and entries 0-3 are reserved iupcx */
377 if (size > 16 - 4)
378 goto fail;
379 profile->file.trans.table = kzalloc(sizeof(char *) * size,
380 GFP_KERNEL);
381 if (!profile->file.trans.table)
382 goto fail;
383
384 profile->file.trans.size = size;
385 for (i = 0; i < size; i++) {
386 char *str;
387 int c, j, size2 = unpack_strdup(e, &str, NULL);
388 /* unpack_strdup verifies that the last character is
389 * null termination byte.
390 */
391 if (!size2)
392 goto fail;
393 profile->file.trans.table[i] = str;
394 /* verify that name doesn't start with space */
395 if (isspace(*str))
396 goto fail;
397
398 /* count internal # of internal \0 */
399 for (c = j = 0; j < size2 - 2; j++) {
400 if (!str[j])
401 c++;
402 }
403 if (*str == ':') {
404 /* beginning with : requires an embedded \0,
405 * verify that exactly 1 internal \0 exists
406 * trailing \0 already verified by unpack_strdup
407 */
408 if (c != 1)
409 goto fail;
410 /* first character after : must be valid */
411 if (!str[1])
412 goto fail;
413 } else if (c)
414 /* fail - all other cases with embedded \0 */
415 goto fail;
416 }
417 if (!unpack_nameX(e, AA_ARRAYEND, NULL))
418 goto fail;
419 if (!unpack_nameX(e, AA_STRUCTEND, NULL))
420 goto fail;
421 }
422 return 1;
423
424fail:
425 aa_free_domain_entries(&profile->file.trans);
426 e->pos = pos;
427 return 0;
428}
429
430static bool unpack_rlimits(struct aa_ext *e, struct aa_profile *profile)
431{
432 void *pos = e->pos;
433
434 /* rlimits are optional */
435 if (unpack_nameX(e, AA_STRUCT, "rlimits")) {
436 int i, size;
437 u32 tmp = 0;
438 if (!unpack_u32(e, &tmp, NULL))
439 goto fail;
440 profile->rlimits.mask = tmp;
441
442 size = unpack_array(e, NULL);
443 if (size > RLIM_NLIMITS)
444 goto fail;
445 for (i = 0; i < size; i++) {
446 u64 tmp2 = 0;
447 int a = aa_map_resource(i);
448 if (!unpack_u64(e, &tmp2, NULL))
449 goto fail;
450 profile->rlimits.limits[a].rlim_max = tmp2;
451 }
452 if (!unpack_nameX(e, AA_ARRAYEND, NULL))
453 goto fail;
454 if (!unpack_nameX(e, AA_STRUCTEND, NULL))
455 goto fail;
456 }
457 return 1;
458
459fail:
460 e->pos = pos;
461 return 0;
462}
463
464/**
465 * unpack_profile - unpack a serialized profile
466 * @e: serialized data extent information (NOT NULL)
467 *
468 * NOTE: unpack profile sets audit struct if there is a failure
469 */
470static struct aa_profile *unpack_profile(struct aa_ext *e)
471{
472 struct aa_profile *profile = NULL;
473 const char *name = NULL;
474 int i, error = -EPROTO;
475 kernel_cap_t tmpcap;
476 u32 tmp;
477
478 /* check that we have the right struct being passed */
479 if (!unpack_nameX(e, AA_STRUCT, "profile"))
480 goto fail;
481 if (!unpack_str(e, &name, NULL))
482 goto fail;
483
484 profile = aa_alloc_profile(name);
485 if (!profile)
486 return ERR_PTR(-ENOMEM);
487
488 /* profile renaming is optional */
489 (void) unpack_str(e, &profile->rename, "rename");
490
491 /* xmatch is optional and may be NULL */
492 profile->xmatch = unpack_dfa(e);
493 if (IS_ERR(profile->xmatch)) {
494 error = PTR_ERR(profile->xmatch);
495 profile->xmatch = NULL;
496 goto fail;
497 }
498 /* xmatch_len is not optional if xmatch is set */
499 if (profile->xmatch) {
500 if (!unpack_u32(e, &tmp, NULL))
501 goto fail;
502 profile->xmatch_len = tmp;
503 }
504
505 /* per profile debug flags (complain, audit) */
506 if (!unpack_nameX(e, AA_STRUCT, "flags"))
507 goto fail;
508 if (!unpack_u32(e, &tmp, NULL))
509 goto fail;
510 if (tmp)
511 profile->flags |= PFLAG_HAT;
512 if (!unpack_u32(e, &tmp, NULL))
513 goto fail;
514 if (tmp)
515 profile->mode = APPARMOR_COMPLAIN;
516 if (!unpack_u32(e, &tmp, NULL))
517 goto fail;
518 if (tmp)
519 profile->audit = AUDIT_ALL;
520
521 if (!unpack_nameX(e, AA_STRUCTEND, NULL))
522 goto fail;
523
524 /* path_flags is optional */
525 if (unpack_u32(e, &profile->path_flags, "path_flags"))
526 profile->path_flags |= profile->flags & PFLAG_MEDIATE_DELETED;
527 else
528 /* set a default value if path_flags field is not present */
529 profile->path_flags = PFLAG_MEDIATE_DELETED;
530
531 if (!unpack_u32(e, &(profile->caps.allow.cap[0]), NULL))
532 goto fail;
533 if (!unpack_u32(e, &(profile->caps.audit.cap[0]), NULL))
534 goto fail;
535 if (!unpack_u32(e, &(profile->caps.quiet.cap[0]), NULL))
536 goto fail;
537 if (!unpack_u32(e, &tmpcap.cap[0], NULL))
538 goto fail;
539
540 if (unpack_nameX(e, AA_STRUCT, "caps64")) {
541 /* optional upper half of 64 bit caps */
542 if (!unpack_u32(e, &(profile->caps.allow.cap[1]), NULL))
543 goto fail;
544 if (!unpack_u32(e, &(profile->caps.audit.cap[1]), NULL))
545 goto fail;
546 if (!unpack_u32(e, &(profile->caps.quiet.cap[1]), NULL))
547 goto fail;
548 if (!unpack_u32(e, &(tmpcap.cap[1]), NULL))
549 goto fail;
550 if (!unpack_nameX(e, AA_STRUCTEND, NULL))
551 goto fail;
552 }
553
554 if (unpack_nameX(e, AA_STRUCT, "capsx")) {
555 /* optional extended caps mediation mask */
556 if (!unpack_u32(e, &(profile->caps.extended.cap[0]), NULL))
557 goto fail;
558 if (!unpack_u32(e, &(profile->caps.extended.cap[1]), NULL))
559 goto fail;
560 if (!unpack_nameX(e, AA_STRUCTEND, NULL))
561 goto fail;
562 }
563
564 if (!unpack_rlimits(e, profile))
565 goto fail;
566
567 if (unpack_nameX(e, AA_STRUCT, "policydb")) {
568 /* generic policy dfa - optional and may be NULL */
569 profile->policy.dfa = unpack_dfa(e);
570 if (IS_ERR(profile->policy.dfa)) {
571 error = PTR_ERR(profile->policy.dfa);
572 profile->policy.dfa = NULL;
573 goto fail;
574 }
575 if (!unpack_u32(e, &profile->policy.start[0], "start"))
576 /* default start state */
577 profile->policy.start[0] = DFA_START;
578 /* setup class index */
579 for (i = AA_CLASS_FILE; i <= AA_CLASS_LAST; i++) {
580 profile->policy.start[i] =
581 aa_dfa_next(profile->policy.dfa,
582 profile->policy.start[0],
583 i);
584 }
585 if (!unpack_nameX(e, AA_STRUCTEND, NULL))
586 goto fail;
587 }
588
589 /* get file rules */
590 profile->file.dfa = unpack_dfa(e);
591 if (IS_ERR(profile->file.dfa)) {
592 error = PTR_ERR(profile->file.dfa);
593 profile->file.dfa = NULL;
594 goto fail;
595 }
596
597 if (!unpack_u32(e, &profile->file.start, "dfa_start"))
598 /* default start state */
599 profile->file.start = DFA_START;
600
601 if (!unpack_trans_table(e, profile))
602 goto fail;
603
604 if (!unpack_nameX(e, AA_STRUCTEND, NULL))
605 goto fail;
606
607 return profile;
608
609fail:
610 if (profile)
611 name = NULL;
612 else if (!name)
613 name = "unknown";
614 audit_iface(profile, name, "failed to unpack profile", e, error);
615 aa_put_profile(profile);
616
617 return ERR_PTR(error);
618}
619
620/**
621 * verify_head - unpack serialized stream header
622 * @e: serialized data read head (NOT NULL)
623 * @ns: Returns - namespace if one is specified else NULL (NOT NULL)
624 *
625 * Returns: error or 0 if header is good
626 */
627static int verify_header(struct aa_ext *e, const char **ns)
628{
629 int error = -EPROTONOSUPPORT;
630 /* get the interface version */
631 if (!unpack_u32(e, &e->version, "version")) {
632 audit_iface(NULL, NULL, "invalid profile format", e, error);
633 return error;
634 }
635
636 /* check that the interface version is currently supported */
637 if (e->version != 5) {
638 audit_iface(NULL, NULL, "unsupported interface version", e,
639 error);
640 return error;
641 }
642
643 /* read the namespace if present */
644 if (!unpack_str(e, ns, "namespace"))
645 *ns = NULL;
646
647 return 0;
648}
649
650static bool verify_xindex(int xindex, int table_size)
651{
652 int index, xtype;
653 xtype = xindex & AA_X_TYPE_MASK;
654 index = xindex & AA_X_INDEX_MASK;
655 if (xtype == AA_X_TABLE && index > table_size)
656 return 0;
657 return 1;
658}
659
660/* verify dfa xindexes are in range of transition tables */
661static bool verify_dfa_xindex(struct aa_dfa *dfa, int table_size)
662{
663 int i;
664 for (i = 0; i < dfa->tables[YYTD_ID_ACCEPT]->td_lolen; i++) {
665 if (!verify_xindex(dfa_user_xindex(dfa, i), table_size))
666 return 0;
667 if (!verify_xindex(dfa_other_xindex(dfa, i), table_size))
668 return 0;
669 }
670 return 1;
671}
672
673/**
674 * verify_profile - Do post unpack analysis to verify profile consistency
675 * @profile: profile to verify (NOT NULL)
676 *
677 * Returns: 0 if passes verification else error
678 */
679static int verify_profile(struct aa_profile *profile)
680{
681 if (aa_g_paranoid_load) {
682 if (profile->file.dfa &&
683 !verify_dfa_xindex(profile->file.dfa,
684 profile->file.trans.size)) {
685 audit_iface(profile, NULL, "Invalid named transition",
686 NULL, -EPROTO);
687 return -EPROTO;
688 }
689 }
690
691 return 0;
692}
693
694/**
695 * aa_unpack - unpack packed binary profile data loaded from user space
696 * @udata: user data copied to kmem (NOT NULL)
697 * @size: the size of the user data
698 * @ns: Returns namespace profile is in if specified else NULL (NOT NULL)
699 *
700 * Unpack user data and return refcounted allocated profile or ERR_PTR
701 *
702 * Returns: profile else error pointer if fails to unpack
703 */
704struct aa_profile *aa_unpack(void *udata, size_t size, const char **ns)
705{
706 struct aa_profile *profile = NULL;
707 int error;
708 struct aa_ext e = {
709 .start = udata,
710 .end = udata + size,
711 .pos = udata,
712 };
713
714 error = verify_header(&e, ns);
715 if (error)
716 return ERR_PTR(error);
717
718 profile = unpack_profile(&e);
719 if (IS_ERR(profile))
720 return profile;
721
722 error = verify_profile(profile);
723 if (error) {
724 aa_put_profile(profile);
725 profile = ERR_PTR(error);
726 }
727
728 /* return refcount */
729 return profile;
730}