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1/*
2 * AppArmor security module
3 *
4 * This file contains AppArmor dfa based regular expression matching engine
5 *
6 * Copyright (C) 1998-2008 Novell/SUSE
7 * Copyright 2009-2012 Canonical Ltd.
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License as
11 * published by the Free Software Foundation, version 2 of the
12 * License.
13 */
14
15#include <linux/errno.h>
16#include <linux/kernel.h>
17#include <linux/mm.h>
18#include <linux/slab.h>
19#include <linux/vmalloc.h>
20#include <linux/err.h>
21#include <linux/kref.h>
22
23#include "include/apparmor.h"
24#include "include/match.h"
25
26#define base_idx(X) ((X) & 0xffffff)
27
28/**
29 * unpack_table - unpack a dfa table (one of accept, default, base, next check)
30 * @blob: data to unpack (NOT NULL)
31 * @bsize: size of blob
32 *
33 * Returns: pointer to table else NULL on failure
34 *
35 * NOTE: must be freed by kvfree (not kfree)
36 */
37static struct table_header *unpack_table(char *blob, size_t bsize)
38{
39 struct table_header *table = NULL;
40 struct table_header th;
41 size_t tsize;
42
43 if (bsize < sizeof(struct table_header))
44 goto out;
45
46 /* loaded td_id's start at 1, subtract 1 now to avoid doing
47 * it every time we use td_id as an index
48 */
49 th.td_id = be16_to_cpu(*(u16 *) (blob)) - 1;
50 th.td_flags = be16_to_cpu(*(u16 *) (blob + 2));
51 th.td_lolen = be32_to_cpu(*(u32 *) (blob + 8));
52 blob += sizeof(struct table_header);
53
54 if (!(th.td_flags == YYTD_DATA16 || th.td_flags == YYTD_DATA32 ||
55 th.td_flags == YYTD_DATA8))
56 goto out;
57
58 tsize = table_size(th.td_lolen, th.td_flags);
59 if (bsize < tsize)
60 goto out;
61
62 table = kvzalloc(tsize);
63 if (table) {
64 *table = th;
65 if (th.td_flags == YYTD_DATA8)
66 UNPACK_ARRAY(table->td_data, blob, th.td_lolen,
67 u8, byte_to_byte);
68 else if (th.td_flags == YYTD_DATA16)
69 UNPACK_ARRAY(table->td_data, blob, th.td_lolen,
70 u16, be16_to_cpu);
71 else if (th.td_flags == YYTD_DATA32)
72 UNPACK_ARRAY(table->td_data, blob, th.td_lolen,
73 u32, be32_to_cpu);
74 else
75 goto fail;
76 }
77
78out:
79 /* if table was vmalloced make sure the page tables are synced
80 * before it is used, as it goes live to all cpus.
81 */
82 if (is_vmalloc_addr(table))
83 vm_unmap_aliases();
84 return table;
85fail:
86 kvfree(table);
87 return NULL;
88}
89
90/**
91 * verify_dfa - verify that transitions and states in the tables are in bounds.
92 * @dfa: dfa to test (NOT NULL)
93 * @flags: flags controlling what type of accept table are acceptable
94 *
95 * Assumes dfa has gone through the first pass verification done by unpacking
96 * NOTE: this does not valid accept table values
97 *
98 * Returns: %0 else error code on failure to verify
99 */
100static int verify_dfa(struct aa_dfa *dfa, int flags)
101{
102 size_t i, state_count, trans_count;
103 int error = -EPROTO;
104
105 /* check that required tables exist */
106 if (!(dfa->tables[YYTD_ID_DEF] &&
107 dfa->tables[YYTD_ID_BASE] &&
108 dfa->tables[YYTD_ID_NXT] && dfa->tables[YYTD_ID_CHK]))
109 goto out;
110
111 /* accept.size == default.size == base.size */
112 state_count = dfa->tables[YYTD_ID_BASE]->td_lolen;
113 if (ACCEPT1_FLAGS(flags)) {
114 if (!dfa->tables[YYTD_ID_ACCEPT])
115 goto out;
116 if (state_count != dfa->tables[YYTD_ID_ACCEPT]->td_lolen)
117 goto out;
118 }
119 if (ACCEPT2_FLAGS(flags)) {
120 if (!dfa->tables[YYTD_ID_ACCEPT2])
121 goto out;
122 if (state_count != dfa->tables[YYTD_ID_ACCEPT2]->td_lolen)
123 goto out;
124 }
125 if (state_count != dfa->tables[YYTD_ID_DEF]->td_lolen)
126 goto out;
127
128 /* next.size == chk.size */
129 trans_count = dfa->tables[YYTD_ID_NXT]->td_lolen;
130 if (trans_count != dfa->tables[YYTD_ID_CHK]->td_lolen)
131 goto out;
132
133 /* if equivalence classes then its table size must be 256 */
134 if (dfa->tables[YYTD_ID_EC] &&
135 dfa->tables[YYTD_ID_EC]->td_lolen != 256)
136 goto out;
137
138 if (flags & DFA_FLAG_VERIFY_STATES) {
139 for (i = 0; i < state_count; i++) {
140 if (DEFAULT_TABLE(dfa)[i] >= state_count)
141 goto out;
142 if (base_idx(BASE_TABLE(dfa)[i]) + 255 >= trans_count) {
143 printk(KERN_ERR "AppArmor DFA next/check upper "
144 "bounds error\n");
145 goto out;
146 }
147 }
148
149 for (i = 0; i < trans_count; i++) {
150 if (NEXT_TABLE(dfa)[i] >= state_count)
151 goto out;
152 if (CHECK_TABLE(dfa)[i] >= state_count)
153 goto out;
154 }
155 }
156
157 error = 0;
158out:
159 return error;
160}
161
162/**
163 * dfa_free - free a dfa allocated by aa_dfa_unpack
164 * @dfa: the dfa to free (MAYBE NULL)
165 *
166 * Requires: reference count to dfa == 0
167 */
168static void dfa_free(struct aa_dfa *dfa)
169{
170 if (dfa) {
171 int i;
172
173 for (i = 0; i < ARRAY_SIZE(dfa->tables); i++) {
174 kvfree(dfa->tables[i]);
175 dfa->tables[i] = NULL;
176 }
177 kfree(dfa);
178 }
179}
180
181/**
182 * aa_dfa_free_kref - free aa_dfa by kref (called by aa_put_dfa)
183 * @kr: kref callback for freeing of a dfa (NOT NULL)
184 */
185void aa_dfa_free_kref(struct kref *kref)
186{
187 struct aa_dfa *dfa = container_of(kref, struct aa_dfa, count);
188 dfa_free(dfa);
189}
190
191/**
192 * aa_dfa_unpack - unpack the binary tables of a serialized dfa
193 * @blob: aligned serialized stream of data to unpack (NOT NULL)
194 * @size: size of data to unpack
195 * @flags: flags controlling what type of accept tables are acceptable
196 *
197 * Unpack a dfa that has been serialized. To find information on the dfa
198 * format look in Documentation/security/apparmor.txt
199 * Assumes the dfa @blob stream has been aligned on a 8 byte boundary
200 *
201 * Returns: an unpacked dfa ready for matching or ERR_PTR on failure
202 */
203struct aa_dfa *aa_dfa_unpack(void *blob, size_t size, int flags)
204{
205 int hsize;
206 int error = -ENOMEM;
207 char *data = blob;
208 struct table_header *table = NULL;
209 struct aa_dfa *dfa = kzalloc(sizeof(struct aa_dfa), GFP_KERNEL);
210 if (!dfa)
211 goto fail;
212
213 kref_init(&dfa->count);
214
215 error = -EPROTO;
216
217 /* get dfa table set header */
218 if (size < sizeof(struct table_set_header))
219 goto fail;
220
221 if (ntohl(*(u32 *) data) != YYTH_MAGIC)
222 goto fail;
223
224 hsize = ntohl(*(u32 *) (data + 4));
225 if (size < hsize)
226 goto fail;
227
228 dfa->flags = ntohs(*(u16 *) (data + 12));
229 data += hsize;
230 size -= hsize;
231
232 while (size > 0) {
233 table = unpack_table(data, size);
234 if (!table)
235 goto fail;
236
237 switch (table->td_id) {
238 case YYTD_ID_ACCEPT:
239 if (!(table->td_flags & ACCEPT1_FLAGS(flags)))
240 goto fail;
241 break;
242 case YYTD_ID_ACCEPT2:
243 if (!(table->td_flags & ACCEPT2_FLAGS(flags)))
244 goto fail;
245 break;
246 case YYTD_ID_BASE:
247 if (table->td_flags != YYTD_DATA32)
248 goto fail;
249 break;
250 case YYTD_ID_DEF:
251 case YYTD_ID_NXT:
252 case YYTD_ID_CHK:
253 if (table->td_flags != YYTD_DATA16)
254 goto fail;
255 break;
256 case YYTD_ID_EC:
257 if (table->td_flags != YYTD_DATA8)
258 goto fail;
259 break;
260 default:
261 goto fail;
262 }
263 /* check for duplicate table entry */
264 if (dfa->tables[table->td_id])
265 goto fail;
266 dfa->tables[table->td_id] = table;
267 data += table_size(table->td_lolen, table->td_flags);
268 size -= table_size(table->td_lolen, table->td_flags);
269 table = NULL;
270 }
271
272 error = verify_dfa(dfa, flags);
273 if (error)
274 goto fail;
275
276 return dfa;
277
278fail:
279 kvfree(table);
280 dfa_free(dfa);
281 return ERR_PTR(error);
282}
283
284/**
285 * aa_dfa_match_len - traverse @dfa to find state @str stops at
286 * @dfa: the dfa to match @str against (NOT NULL)
287 * @start: the state of the dfa to start matching in
288 * @str: the string of bytes to match against the dfa (NOT NULL)
289 * @len: length of the string of bytes to match
290 *
291 * aa_dfa_match_len will match @str against the dfa and return the state it
292 * finished matching in. The final state can be used to look up the accepting
293 * label, or as the start state of a continuing match.
294 *
295 * This function will happily match again the 0 byte and only finishes
296 * when @len input is consumed.
297 *
298 * Returns: final state reached after input is consumed
299 */
300unsigned int aa_dfa_match_len(struct aa_dfa *dfa, unsigned int start,
301 const char *str, int len)
302{
303 u16 *def = DEFAULT_TABLE(dfa);
304 u32 *base = BASE_TABLE(dfa);
305 u16 *next = NEXT_TABLE(dfa);
306 u16 *check = CHECK_TABLE(dfa);
307 unsigned int state = start, pos;
308
309 if (state == 0)
310 return 0;
311
312 /* current state is <state>, matching character *str */
313 if (dfa->tables[YYTD_ID_EC]) {
314 /* Equivalence class table defined */
315 u8 *equiv = EQUIV_TABLE(dfa);
316 /* default is direct to next state */
317 for (; len; len--) {
318 pos = base_idx(base[state]) + equiv[(u8) *str++];
319 if (check[pos] == state)
320 state = next[pos];
321 else
322 state = def[state];
323 }
324 } else {
325 /* default is direct to next state */
326 for (; len; len--) {
327 pos = base_idx(base[state]) + (u8) *str++;
328 if (check[pos] == state)
329 state = next[pos];
330 else
331 state = def[state];
332 }
333 }
334
335 return state;
336}
337
338/**
339 * aa_dfa_match - traverse @dfa to find state @str stops at
340 * @dfa: the dfa to match @str against (NOT NULL)
341 * @start: the state of the dfa to start matching in
342 * @str: the null terminated string of bytes to match against the dfa (NOT NULL)
343 *
344 * aa_dfa_match will match @str against the dfa and return the state it
345 * finished matching in. The final state can be used to look up the accepting
346 * label, or as the start state of a continuing match.
347 *
348 * Returns: final state reached after input is consumed
349 */
350unsigned int aa_dfa_match(struct aa_dfa *dfa, unsigned int start,
351 const char *str)
352{
353 u16 *def = DEFAULT_TABLE(dfa);
354 u32 *base = BASE_TABLE(dfa);
355 u16 *next = NEXT_TABLE(dfa);
356 u16 *check = CHECK_TABLE(dfa);
357 unsigned int state = start, pos;
358
359 if (state == 0)
360 return 0;
361
362 /* current state is <state>, matching character *str */
363 if (dfa->tables[YYTD_ID_EC]) {
364 /* Equivalence class table defined */
365 u8 *equiv = EQUIV_TABLE(dfa);
366 /* default is direct to next state */
367 while (*str) {
368 pos = base_idx(base[state]) + equiv[(u8) *str++];
369 if (check[pos] == state)
370 state = next[pos];
371 else
372 state = def[state];
373 }
374 } else {
375 /* default is direct to next state */
376 while (*str) {
377 pos = base_idx(base[state]) + (u8) *str++;
378 if (check[pos] == state)
379 state = next[pos];
380 else
381 state = def[state];
382 }
383 }
384
385 return state;
386}
387
388/**
389 * aa_dfa_next - step one character to the next state in the dfa
390 * @dfa: the dfa to tranverse (NOT NULL)
391 * @state: the state to start in
392 * @c: the input character to transition on
393 *
394 * aa_dfa_match will step through the dfa by one input character @c
395 *
396 * Returns: state reach after input @c
397 */
398unsigned int aa_dfa_next(struct aa_dfa *dfa, unsigned int state,
399 const char c)
400{
401 u16 *def = DEFAULT_TABLE(dfa);
402 u32 *base = BASE_TABLE(dfa);
403 u16 *next = NEXT_TABLE(dfa);
404 u16 *check = CHECK_TABLE(dfa);
405 unsigned int pos;
406
407 /* current state is <state>, matching character *str */
408 if (dfa->tables[YYTD_ID_EC]) {
409 /* Equivalence class table defined */
410 u8 *equiv = EQUIV_TABLE(dfa);
411 /* default is direct to next state */
412
413 pos = base_idx(base[state]) + equiv[(u8) c];
414 if (check[pos] == state)
415 state = next[pos];
416 else
417 state = def[state];
418 } else {
419 /* default is direct to next state */
420 pos = base_idx(base[state]) + (u8) c;
421 if (check[pos] == state)
422 state = next[pos];
423 else
424 state = def[state];
425 }
426
427 return state;
428}
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * AppArmor security module
4 *
5 * This file contains AppArmor dfa based regular expression matching engine
6 *
7 * Copyright (C) 1998-2008 Novell/SUSE
8 * Copyright 2009-2012 Canonical Ltd.
9 */
10
11#include <linux/errno.h>
12#include <linux/kernel.h>
13#include <linux/mm.h>
14#include <linux/slab.h>
15#include <linux/vmalloc.h>
16#include <linux/err.h>
17#include <linux/kref.h>
18
19#include "include/lib.h"
20#include "include/match.h"
21
22#define base_idx(X) ((X) & 0xffffff)
23
24static char nulldfa_src[] = {
25 #include "nulldfa.in"
26};
27struct aa_dfa *nulldfa;
28
29static char stacksplitdfa_src[] = {
30 #include "stacksplitdfa.in"
31};
32struct aa_dfa *stacksplitdfa;
33
34int __init aa_setup_dfa_engine(void)
35{
36 int error;
37
38 nulldfa = aa_dfa_unpack(nulldfa_src, sizeof(nulldfa_src),
39 TO_ACCEPT1_FLAG(YYTD_DATA32) |
40 TO_ACCEPT2_FLAG(YYTD_DATA32));
41 if (IS_ERR(nulldfa)) {
42 error = PTR_ERR(nulldfa);
43 nulldfa = NULL;
44 return error;
45 }
46
47 stacksplitdfa = aa_dfa_unpack(stacksplitdfa_src,
48 sizeof(stacksplitdfa_src),
49 TO_ACCEPT1_FLAG(YYTD_DATA32) |
50 TO_ACCEPT2_FLAG(YYTD_DATA32));
51 if (IS_ERR(stacksplitdfa)) {
52 aa_put_dfa(nulldfa);
53 nulldfa = NULL;
54 error = PTR_ERR(stacksplitdfa);
55 stacksplitdfa = NULL;
56 return error;
57 }
58
59 return 0;
60}
61
62void __init aa_teardown_dfa_engine(void)
63{
64 aa_put_dfa(stacksplitdfa);
65 aa_put_dfa(nulldfa);
66}
67
68/**
69 * unpack_table - unpack a dfa table (one of accept, default, base, next check)
70 * @blob: data to unpack (NOT NULL)
71 * @bsize: size of blob
72 *
73 * Returns: pointer to table else NULL on failure
74 *
75 * NOTE: must be freed by kvfree (not kfree)
76 */
77static struct table_header *unpack_table(char *blob, size_t bsize)
78{
79 struct table_header *table = NULL;
80 struct table_header th;
81 size_t tsize;
82
83 if (bsize < sizeof(struct table_header))
84 goto out;
85
86 /* loaded td_id's start at 1, subtract 1 now to avoid doing
87 * it every time we use td_id as an index
88 */
89 th.td_id = be16_to_cpu(*(__be16 *) (blob)) - 1;
90 if (th.td_id > YYTD_ID_MAX)
91 goto out;
92 th.td_flags = be16_to_cpu(*(__be16 *) (blob + 2));
93 th.td_lolen = be32_to_cpu(*(__be32 *) (blob + 8));
94 blob += sizeof(struct table_header);
95
96 if (!(th.td_flags == YYTD_DATA16 || th.td_flags == YYTD_DATA32 ||
97 th.td_flags == YYTD_DATA8))
98 goto out;
99
100 /* if we have a table it must have some entries */
101 if (th.td_lolen == 0)
102 goto out;
103 tsize = table_size(th.td_lolen, th.td_flags);
104 if (bsize < tsize)
105 goto out;
106
107 table = kvzalloc(tsize, GFP_KERNEL);
108 if (table) {
109 table->td_id = th.td_id;
110 table->td_flags = th.td_flags;
111 table->td_lolen = th.td_lolen;
112 if (th.td_flags == YYTD_DATA8)
113 UNPACK_ARRAY(table->td_data, blob, th.td_lolen,
114 u8, u8, byte_to_byte);
115 else if (th.td_flags == YYTD_DATA16)
116 UNPACK_ARRAY(table->td_data, blob, th.td_lolen,
117 u16, __be16, be16_to_cpu);
118 else if (th.td_flags == YYTD_DATA32)
119 UNPACK_ARRAY(table->td_data, blob, th.td_lolen,
120 u32, __be32, be32_to_cpu);
121 else
122 goto fail;
123 /* if table was vmalloced make sure the page tables are synced
124 * before it is used, as it goes live to all cpus.
125 */
126 if (is_vmalloc_addr(table))
127 vm_unmap_aliases();
128 }
129
130out:
131 return table;
132fail:
133 kvfree(table);
134 return NULL;
135}
136
137/**
138 * verify_table_headers - verify that the tables headers are as expected
139 * @tables - array of dfa tables to check (NOT NULL)
140 * @flags: flags controlling what type of accept table are acceptable
141 *
142 * Assumes dfa has gone through the first pass verification done by unpacking
143 * NOTE: this does not valid accept table values
144 *
145 * Returns: %0 else error code on failure to verify
146 */
147static int verify_table_headers(struct table_header **tables, int flags)
148{
149 size_t state_count, trans_count;
150 int error = -EPROTO;
151
152 /* check that required tables exist */
153 if (!(tables[YYTD_ID_DEF] && tables[YYTD_ID_BASE] &&
154 tables[YYTD_ID_NXT] && tables[YYTD_ID_CHK]))
155 goto out;
156
157 /* accept.size == default.size == base.size */
158 state_count = tables[YYTD_ID_BASE]->td_lolen;
159 if (ACCEPT1_FLAGS(flags)) {
160 if (!tables[YYTD_ID_ACCEPT])
161 goto out;
162 if (state_count != tables[YYTD_ID_ACCEPT]->td_lolen)
163 goto out;
164 }
165 if (ACCEPT2_FLAGS(flags)) {
166 if (!tables[YYTD_ID_ACCEPT2])
167 goto out;
168 if (state_count != tables[YYTD_ID_ACCEPT2]->td_lolen)
169 goto out;
170 }
171 if (state_count != tables[YYTD_ID_DEF]->td_lolen)
172 goto out;
173
174 /* next.size == chk.size */
175 trans_count = tables[YYTD_ID_NXT]->td_lolen;
176 if (trans_count != tables[YYTD_ID_CHK]->td_lolen)
177 goto out;
178
179 /* if equivalence classes then its table size must be 256 */
180 if (tables[YYTD_ID_EC] && tables[YYTD_ID_EC]->td_lolen != 256)
181 goto out;
182
183 error = 0;
184out:
185 return error;
186}
187
188/**
189 * verify_dfa - verify that transitions and states in the tables are in bounds.
190 * @dfa: dfa to test (NOT NULL)
191 *
192 * Assumes dfa has gone through the first pass verification done by unpacking
193 * NOTE: this does not valid accept table values
194 *
195 * Returns: %0 else error code on failure to verify
196 */
197static int verify_dfa(struct aa_dfa *dfa)
198{
199 size_t i, state_count, trans_count;
200 int error = -EPROTO;
201
202 state_count = dfa->tables[YYTD_ID_BASE]->td_lolen;
203 trans_count = dfa->tables[YYTD_ID_NXT]->td_lolen;
204 if (state_count == 0)
205 goto out;
206 for (i = 0; i < state_count; i++) {
207 if (!(BASE_TABLE(dfa)[i] & MATCH_FLAG_DIFF_ENCODE) &&
208 (DEFAULT_TABLE(dfa)[i] >= state_count))
209 goto out;
210 if (BASE_TABLE(dfa)[i] & MATCH_FLAGS_INVALID) {
211 pr_err("AppArmor DFA state with invalid match flags");
212 goto out;
213 }
214 if ((BASE_TABLE(dfa)[i] & MATCH_FLAG_DIFF_ENCODE)) {
215 if (!(dfa->flags & YYTH_FLAG_DIFF_ENCODE)) {
216 pr_err("AppArmor DFA diff encoded transition state without header flag");
217 goto out;
218 }
219 }
220 if ((BASE_TABLE(dfa)[i] & MATCH_FLAG_OOB_TRANSITION)) {
221 if (base_idx(BASE_TABLE(dfa)[i]) < dfa->max_oob) {
222 pr_err("AppArmor DFA out of bad transition out of range");
223 goto out;
224 }
225 if (!(dfa->flags & YYTH_FLAG_OOB_TRANS)) {
226 pr_err("AppArmor DFA out of bad transition state without header flag");
227 goto out;
228 }
229 }
230 if (base_idx(BASE_TABLE(dfa)[i]) + 255 >= trans_count) {
231 pr_err("AppArmor DFA next/check upper bounds error\n");
232 goto out;
233 }
234 }
235
236 for (i = 0; i < trans_count; i++) {
237 if (NEXT_TABLE(dfa)[i] >= state_count)
238 goto out;
239 if (CHECK_TABLE(dfa)[i] >= state_count)
240 goto out;
241 }
242
243 /* Now that all the other tables are verified, verify diffencoding */
244 for (i = 0; i < state_count; i++) {
245 size_t j, k;
246
247 for (j = i;
248 (BASE_TABLE(dfa)[j] & MATCH_FLAG_DIFF_ENCODE) &&
249 !(BASE_TABLE(dfa)[j] & MARK_DIFF_ENCODE);
250 j = k) {
251 k = DEFAULT_TABLE(dfa)[j];
252 if (j == k)
253 goto out;
254 if (k < j)
255 break; /* already verified */
256 BASE_TABLE(dfa)[j] |= MARK_DIFF_ENCODE;
257 }
258 }
259 error = 0;
260
261out:
262 return error;
263}
264
265/**
266 * dfa_free - free a dfa allocated by aa_dfa_unpack
267 * @dfa: the dfa to free (MAYBE NULL)
268 *
269 * Requires: reference count to dfa == 0
270 */
271static void dfa_free(struct aa_dfa *dfa)
272{
273 if (dfa) {
274 int i;
275
276 for (i = 0; i < ARRAY_SIZE(dfa->tables); i++) {
277 kvfree(dfa->tables[i]);
278 dfa->tables[i] = NULL;
279 }
280 kfree(dfa);
281 }
282}
283
284/**
285 * aa_dfa_free_kref - free aa_dfa by kref (called by aa_put_dfa)
286 * @kr: kref callback for freeing of a dfa (NOT NULL)
287 */
288void aa_dfa_free_kref(struct kref *kref)
289{
290 struct aa_dfa *dfa = container_of(kref, struct aa_dfa, count);
291 dfa_free(dfa);
292}
293
294/**
295 * aa_dfa_unpack - unpack the binary tables of a serialized dfa
296 * @blob: aligned serialized stream of data to unpack (NOT NULL)
297 * @size: size of data to unpack
298 * @flags: flags controlling what type of accept tables are acceptable
299 *
300 * Unpack a dfa that has been serialized. To find information on the dfa
301 * format look in Documentation/admin-guide/LSM/apparmor.rst
302 * Assumes the dfa @blob stream has been aligned on a 8 byte boundary
303 *
304 * Returns: an unpacked dfa ready for matching or ERR_PTR on failure
305 */
306struct aa_dfa *aa_dfa_unpack(void *blob, size_t size, int flags)
307{
308 int hsize;
309 int error = -ENOMEM;
310 char *data = blob;
311 struct table_header *table = NULL;
312 struct aa_dfa *dfa = kzalloc(sizeof(struct aa_dfa), GFP_KERNEL);
313 if (!dfa)
314 goto fail;
315
316 kref_init(&dfa->count);
317
318 error = -EPROTO;
319
320 /* get dfa table set header */
321 if (size < sizeof(struct table_set_header))
322 goto fail;
323
324 if (ntohl(*(__be32 *) data) != YYTH_MAGIC)
325 goto fail;
326
327 hsize = ntohl(*(__be32 *) (data + 4));
328 if (size < hsize)
329 goto fail;
330
331 dfa->flags = ntohs(*(__be16 *) (data + 12));
332 if (dfa->flags & ~(YYTH_FLAGS))
333 goto fail;
334
335 /*
336 * TODO: needed for dfa to support more than 1 oob
337 * if (dfa->flags & YYTH_FLAGS_OOB_TRANS) {
338 * if (hsize < 16 + 4)
339 * goto fail;
340 * dfa->max_oob = ntol(*(__be32 *) (data + 16));
341 * if (dfa->max <= MAX_OOB_SUPPORTED) {
342 * pr_err("AppArmor DFA OOB greater than supported\n");
343 * goto fail;
344 * }
345 * }
346 */
347 dfa->max_oob = 1;
348
349 data += hsize;
350 size -= hsize;
351
352 while (size > 0) {
353 table = unpack_table(data, size);
354 if (!table)
355 goto fail;
356
357 switch (table->td_id) {
358 case YYTD_ID_ACCEPT:
359 if (!(table->td_flags & ACCEPT1_FLAGS(flags)))
360 goto fail;
361 break;
362 case YYTD_ID_ACCEPT2:
363 if (!(table->td_flags & ACCEPT2_FLAGS(flags)))
364 goto fail;
365 break;
366 case YYTD_ID_BASE:
367 if (table->td_flags != YYTD_DATA32)
368 goto fail;
369 break;
370 case YYTD_ID_DEF:
371 case YYTD_ID_NXT:
372 case YYTD_ID_CHK:
373 if (table->td_flags != YYTD_DATA16)
374 goto fail;
375 break;
376 case YYTD_ID_EC:
377 if (table->td_flags != YYTD_DATA8)
378 goto fail;
379 break;
380 default:
381 goto fail;
382 }
383 /* check for duplicate table entry */
384 if (dfa->tables[table->td_id])
385 goto fail;
386 dfa->tables[table->td_id] = table;
387 data += table_size(table->td_lolen, table->td_flags);
388 size -= table_size(table->td_lolen, table->td_flags);
389 table = NULL;
390 }
391 error = verify_table_headers(dfa->tables, flags);
392 if (error)
393 goto fail;
394
395 if (flags & DFA_FLAG_VERIFY_STATES) {
396 error = verify_dfa(dfa);
397 if (error)
398 goto fail;
399 }
400
401 return dfa;
402
403fail:
404 kvfree(table);
405 dfa_free(dfa);
406 return ERR_PTR(error);
407}
408
409#define match_char(state, def, base, next, check, C) \
410do { \
411 u32 b = (base)[(state)]; \
412 unsigned int pos = base_idx(b) + (C); \
413 if ((check)[pos] != (state)) { \
414 (state) = (def)[(state)]; \
415 if (b & MATCH_FLAG_DIFF_ENCODE) \
416 continue; \
417 break; \
418 } \
419 (state) = (next)[pos]; \
420 break; \
421} while (1)
422
423/**
424 * aa_dfa_match_len - traverse @dfa to find state @str stops at
425 * @dfa: the dfa to match @str against (NOT NULL)
426 * @start: the state of the dfa to start matching in
427 * @str: the string of bytes to match against the dfa (NOT NULL)
428 * @len: length of the string of bytes to match
429 *
430 * aa_dfa_match_len will match @str against the dfa and return the state it
431 * finished matching in. The final state can be used to look up the accepting
432 * label, or as the start state of a continuing match.
433 *
434 * This function will happily match again the 0 byte and only finishes
435 * when @len input is consumed.
436 *
437 * Returns: final state reached after input is consumed
438 */
439aa_state_t aa_dfa_match_len(struct aa_dfa *dfa, aa_state_t start,
440 const char *str, int len)
441{
442 u16 *def = DEFAULT_TABLE(dfa);
443 u32 *base = BASE_TABLE(dfa);
444 u16 *next = NEXT_TABLE(dfa);
445 u16 *check = CHECK_TABLE(dfa);
446 aa_state_t state = start;
447
448 if (state == DFA_NOMATCH)
449 return DFA_NOMATCH;
450
451 /* current state is <state>, matching character *str */
452 if (dfa->tables[YYTD_ID_EC]) {
453 /* Equivalence class table defined */
454 u8 *equiv = EQUIV_TABLE(dfa);
455 for (; len; len--)
456 match_char(state, def, base, next, check,
457 equiv[(u8) *str++]);
458 } else {
459 /* default is direct to next state */
460 for (; len; len--)
461 match_char(state, def, base, next, check, (u8) *str++);
462 }
463
464 return state;
465}
466
467/**
468 * aa_dfa_match - traverse @dfa to find state @str stops at
469 * @dfa: the dfa to match @str against (NOT NULL)
470 * @start: the state of the dfa to start matching in
471 * @str: the null terminated string of bytes to match against the dfa (NOT NULL)
472 *
473 * aa_dfa_match will match @str against the dfa and return the state it
474 * finished matching in. The final state can be used to look up the accepting
475 * label, or as the start state of a continuing match.
476 *
477 * Returns: final state reached after input is consumed
478 */
479aa_state_t aa_dfa_match(struct aa_dfa *dfa, aa_state_t start, const char *str)
480{
481 u16 *def = DEFAULT_TABLE(dfa);
482 u32 *base = BASE_TABLE(dfa);
483 u16 *next = NEXT_TABLE(dfa);
484 u16 *check = CHECK_TABLE(dfa);
485 aa_state_t state = start;
486
487 if (state == DFA_NOMATCH)
488 return DFA_NOMATCH;
489
490 /* current state is <state>, matching character *str */
491 if (dfa->tables[YYTD_ID_EC]) {
492 /* Equivalence class table defined */
493 u8 *equiv = EQUIV_TABLE(dfa);
494 /* default is direct to next state */
495 while (*str)
496 match_char(state, def, base, next, check,
497 equiv[(u8) *str++]);
498 } else {
499 /* default is direct to next state */
500 while (*str)
501 match_char(state, def, base, next, check, (u8) *str++);
502 }
503
504 return state;
505}
506
507/**
508 * aa_dfa_next - step one character to the next state in the dfa
509 * @dfa: the dfa to traverse (NOT NULL)
510 * @state: the state to start in
511 * @c: the input character to transition on
512 *
513 * aa_dfa_match will step through the dfa by one input character @c
514 *
515 * Returns: state reach after input @c
516 */
517aa_state_t aa_dfa_next(struct aa_dfa *dfa, aa_state_t state, const char c)
518{
519 u16 *def = DEFAULT_TABLE(dfa);
520 u32 *base = BASE_TABLE(dfa);
521 u16 *next = NEXT_TABLE(dfa);
522 u16 *check = CHECK_TABLE(dfa);
523
524 /* current state is <state>, matching character *str */
525 if (dfa->tables[YYTD_ID_EC]) {
526 /* Equivalence class table defined */
527 u8 *equiv = EQUIV_TABLE(dfa);
528 match_char(state, def, base, next, check, equiv[(u8) c]);
529 } else
530 match_char(state, def, base, next, check, (u8) c);
531
532 return state;
533}
534
535aa_state_t aa_dfa_outofband_transition(struct aa_dfa *dfa, aa_state_t state)
536{
537 u16 *def = DEFAULT_TABLE(dfa);
538 u32 *base = BASE_TABLE(dfa);
539 u16 *next = NEXT_TABLE(dfa);
540 u16 *check = CHECK_TABLE(dfa);
541 u32 b = (base)[(state)];
542
543 if (!(b & MATCH_FLAG_OOB_TRANSITION))
544 return DFA_NOMATCH;
545
546 /* No Equivalence class remapping for outofband transitions */
547 match_char(state, def, base, next, check, -1);
548
549 return state;
550}
551
552/**
553 * aa_dfa_match_until - traverse @dfa until accept state or end of input
554 * @dfa: the dfa to match @str against (NOT NULL)
555 * @start: the state of the dfa to start matching in
556 * @str: the null terminated string of bytes to match against the dfa (NOT NULL)
557 * @retpos: first character in str after match OR end of string
558 *
559 * aa_dfa_match will match @str against the dfa and return the state it
560 * finished matching in. The final state can be used to look up the accepting
561 * label, or as the start state of a continuing match.
562 *
563 * Returns: final state reached after input is consumed
564 */
565aa_state_t aa_dfa_match_until(struct aa_dfa *dfa, aa_state_t start,
566 const char *str, const char **retpos)
567{
568 u16 *def = DEFAULT_TABLE(dfa);
569 u32 *base = BASE_TABLE(dfa);
570 u16 *next = NEXT_TABLE(dfa);
571 u16 *check = CHECK_TABLE(dfa);
572 u32 *accept = ACCEPT_TABLE(dfa);
573 aa_state_t state = start, pos;
574
575 if (state == DFA_NOMATCH)
576 return DFA_NOMATCH;
577
578 /* current state is <state>, matching character *str */
579 if (dfa->tables[YYTD_ID_EC]) {
580 /* Equivalence class table defined */
581 u8 *equiv = EQUIV_TABLE(dfa);
582 /* default is direct to next state */
583 while (*str) {
584 pos = base_idx(base[state]) + equiv[(u8) *str++];
585 if (check[pos] == state)
586 state = next[pos];
587 else
588 state = def[state];
589 if (accept[state])
590 break;
591 }
592 } else {
593 /* default is direct to next state */
594 while (*str) {
595 pos = base_idx(base[state]) + (u8) *str++;
596 if (check[pos] == state)
597 state = next[pos];
598 else
599 state = def[state];
600 if (accept[state])
601 break;
602 }
603 }
604
605 *retpos = str;
606 return state;
607}
608
609/**
610 * aa_dfa_matchn_until - traverse @dfa until accept or @n bytes consumed
611 * @dfa: the dfa to match @str against (NOT NULL)
612 * @start: the state of the dfa to start matching in
613 * @str: the string of bytes to match against the dfa (NOT NULL)
614 * @n: length of the string of bytes to match
615 * @retpos: first character in str after match OR str + n
616 *
617 * aa_dfa_match_len will match @str against the dfa and return the state it
618 * finished matching in. The final state can be used to look up the accepting
619 * label, or as the start state of a continuing match.
620 *
621 * This function will happily match again the 0 byte and only finishes
622 * when @n input is consumed.
623 *
624 * Returns: final state reached after input is consumed
625 */
626aa_state_t aa_dfa_matchn_until(struct aa_dfa *dfa, aa_state_t start,
627 const char *str, int n, const char **retpos)
628{
629 u16 *def = DEFAULT_TABLE(dfa);
630 u32 *base = BASE_TABLE(dfa);
631 u16 *next = NEXT_TABLE(dfa);
632 u16 *check = CHECK_TABLE(dfa);
633 u32 *accept = ACCEPT_TABLE(dfa);
634 aa_state_t state = start, pos;
635
636 *retpos = NULL;
637 if (state == DFA_NOMATCH)
638 return DFA_NOMATCH;
639
640 /* current state is <state>, matching character *str */
641 if (dfa->tables[YYTD_ID_EC]) {
642 /* Equivalence class table defined */
643 u8 *equiv = EQUIV_TABLE(dfa);
644 /* default is direct to next state */
645 for (; n; n--) {
646 pos = base_idx(base[state]) + equiv[(u8) *str++];
647 if (check[pos] == state)
648 state = next[pos];
649 else
650 state = def[state];
651 if (accept[state])
652 break;
653 }
654 } else {
655 /* default is direct to next state */
656 for (; n; n--) {
657 pos = base_idx(base[state]) + (u8) *str++;
658 if (check[pos] == state)
659 state = next[pos];
660 else
661 state = def[state];
662 if (accept[state])
663 break;
664 }
665 }
666
667 *retpos = str;
668 return state;
669}
670
671#define inc_wb_pos(wb) \
672do { \
673 wb->pos = (wb->pos + 1) & (WB_HISTORY_SIZE - 1); \
674 wb->len = (wb->len + 1) & (WB_HISTORY_SIZE - 1); \
675} while (0)
676
677/* For DFAs that don't support extended tagging of states */
678static bool is_loop(struct match_workbuf *wb, aa_state_t state,
679 unsigned int *adjust)
680{
681 aa_state_t pos = wb->pos;
682 aa_state_t i;
683
684 if (wb->history[pos] < state)
685 return false;
686
687 for (i = 0; i <= wb->len; i++) {
688 if (wb->history[pos] == state) {
689 *adjust = i;
690 return true;
691 }
692 if (pos == 0)
693 pos = WB_HISTORY_SIZE;
694 pos--;
695 }
696
697 *adjust = i;
698 return true;
699}
700
701static aa_state_t leftmatch_fb(struct aa_dfa *dfa, aa_state_t start,
702 const char *str, struct match_workbuf *wb,
703 unsigned int *count)
704{
705 u16 *def = DEFAULT_TABLE(dfa);
706 u32 *base = BASE_TABLE(dfa);
707 u16 *next = NEXT_TABLE(dfa);
708 u16 *check = CHECK_TABLE(dfa);
709 aa_state_t state = start, pos;
710
711 AA_BUG(!dfa);
712 AA_BUG(!str);
713 AA_BUG(!wb);
714 AA_BUG(!count);
715
716 *count = 0;
717 if (state == DFA_NOMATCH)
718 return DFA_NOMATCH;
719
720 /* current state is <state>, matching character *str */
721 if (dfa->tables[YYTD_ID_EC]) {
722 /* Equivalence class table defined */
723 u8 *equiv = EQUIV_TABLE(dfa);
724 /* default is direct to next state */
725 while (*str) {
726 unsigned int adjust;
727
728 wb->history[wb->pos] = state;
729 pos = base_idx(base[state]) + equiv[(u8) *str++];
730 if (check[pos] == state)
731 state = next[pos];
732 else
733 state = def[state];
734 if (is_loop(wb, state, &adjust)) {
735 state = aa_dfa_match(dfa, state, str);
736 *count -= adjust;
737 goto out;
738 }
739 inc_wb_pos(wb);
740 (*count)++;
741 }
742 } else {
743 /* default is direct to next state */
744 while (*str) {
745 unsigned int adjust;
746
747 wb->history[wb->pos] = state;
748 pos = base_idx(base[state]) + (u8) *str++;
749 if (check[pos] == state)
750 state = next[pos];
751 else
752 state = def[state];
753 if (is_loop(wb, state, &adjust)) {
754 state = aa_dfa_match(dfa, state, str);
755 *count -= adjust;
756 goto out;
757 }
758 inc_wb_pos(wb);
759 (*count)++;
760 }
761 }
762
763out:
764 if (!state)
765 *count = 0;
766 return state;
767}
768
769/**
770 * aa_dfa_leftmatch - traverse @dfa to find state @str stops at
771 * @dfa: the dfa to match @str against (NOT NULL)
772 * @start: the state of the dfa to start matching in
773 * @str: the null terminated string of bytes to match against the dfa (NOT NULL)
774 * @count: current count of longest left.
775 *
776 * aa_dfa_match will match @str against the dfa and return the state it
777 * finished matching in. The final state can be used to look up the accepting
778 * label, or as the start state of a continuing match.
779 *
780 * Returns: final state reached after input is consumed
781 */
782aa_state_t aa_dfa_leftmatch(struct aa_dfa *dfa, aa_state_t start,
783 const char *str, unsigned int *count)
784{
785 DEFINE_MATCH_WB(wb);
786
787 /* TODO: match for extended state dfas */
788
789 return leftmatch_fb(dfa, start, str, &wb, count);
790}