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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/*
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 if (th.td_id > YYTD_ID_MAX)
51 goto out;
52 th.td_flags = be16_to_cpu(*(u16 *) (blob + 2));
53 th.td_lolen = be32_to_cpu(*(u32 *) (blob + 8));
54 blob += sizeof(struct table_header);
55
56 if (!(th.td_flags == YYTD_DATA16 || th.td_flags == YYTD_DATA32 ||
57 th.td_flags == YYTD_DATA8))
58 goto out;
59
60 tsize = table_size(th.td_lolen, th.td_flags);
61 if (bsize < tsize)
62 goto out;
63
64 table = kvzalloc(tsize);
65 if (table) {
66 table->td_id = th.td_id;
67 table->td_flags = th.td_flags;
68 table->td_lolen = th.td_lolen;
69 if (th.td_flags == YYTD_DATA8)
70 UNPACK_ARRAY(table->td_data, blob, th.td_lolen,
71 u8, byte_to_byte);
72 else if (th.td_flags == YYTD_DATA16)
73 UNPACK_ARRAY(table->td_data, blob, th.td_lolen,
74 u16, be16_to_cpu);
75 else if (th.td_flags == YYTD_DATA32)
76 UNPACK_ARRAY(table->td_data, blob, th.td_lolen,
77 u32, be32_to_cpu);
78 else
79 goto fail;
80 /* if table was vmalloced make sure the page tables are synced
81 * before it is used, as it goes live to all cpus.
82 */
83 if (is_vmalloc_addr(table))
84 vm_unmap_aliases();
85 }
86
87out:
88 return table;
89fail:
90 kvfree(table);
91 return NULL;
92}
93
94/**
95 * verify_dfa - verify that transitions and states in the tables are in bounds.
96 * @dfa: dfa to test (NOT NULL)
97 * @flags: flags controlling what type of accept table are acceptable
98 *
99 * Assumes dfa has gone through the first pass verification done by unpacking
100 * NOTE: this does not valid accept table values
101 *
102 * Returns: %0 else error code on failure to verify
103 */
104static int verify_dfa(struct aa_dfa *dfa, int flags)
105{
106 size_t i, state_count, trans_count;
107 int error = -EPROTO;
108
109 /* check that required tables exist */
110 if (!(dfa->tables[YYTD_ID_DEF] &&
111 dfa->tables[YYTD_ID_BASE] &&
112 dfa->tables[YYTD_ID_NXT] && dfa->tables[YYTD_ID_CHK]))
113 goto out;
114
115 /* accept.size == default.size == base.size */
116 state_count = dfa->tables[YYTD_ID_BASE]->td_lolen;
117 if (ACCEPT1_FLAGS(flags)) {
118 if (!dfa->tables[YYTD_ID_ACCEPT])
119 goto out;
120 if (state_count != dfa->tables[YYTD_ID_ACCEPT]->td_lolen)
121 goto out;
122 }
123 if (ACCEPT2_FLAGS(flags)) {
124 if (!dfa->tables[YYTD_ID_ACCEPT2])
125 goto out;
126 if (state_count != dfa->tables[YYTD_ID_ACCEPT2]->td_lolen)
127 goto out;
128 }
129 if (state_count != dfa->tables[YYTD_ID_DEF]->td_lolen)
130 goto out;
131
132 /* next.size == chk.size */
133 trans_count = dfa->tables[YYTD_ID_NXT]->td_lolen;
134 if (trans_count != dfa->tables[YYTD_ID_CHK]->td_lolen)
135 goto out;
136
137 /* if equivalence classes then its table size must be 256 */
138 if (dfa->tables[YYTD_ID_EC] &&
139 dfa->tables[YYTD_ID_EC]->td_lolen != 256)
140 goto out;
141
142 if (flags & DFA_FLAG_VERIFY_STATES) {
143 for (i = 0; i < state_count; i++) {
144 if (DEFAULT_TABLE(dfa)[i] >= state_count)
145 goto out;
146 if (base_idx(BASE_TABLE(dfa)[i]) + 255 >= trans_count) {
147 printk(KERN_ERR "AppArmor DFA next/check upper "
148 "bounds error\n");
149 goto out;
150 }
151 }
152
153 for (i = 0; i < trans_count; i++) {
154 if (NEXT_TABLE(dfa)[i] >= state_count)
155 goto out;
156 if (CHECK_TABLE(dfa)[i] >= state_count)
157 goto out;
158 }
159 }
160
161 error = 0;
162out:
163 return error;
164}
165
166/**
167 * dfa_free - free a dfa allocated by aa_dfa_unpack
168 * @dfa: the dfa to free (MAYBE NULL)
169 *
170 * Requires: reference count to dfa == 0
171 */
172static void dfa_free(struct aa_dfa *dfa)
173{
174 if (dfa) {
175 int i;
176
177 for (i = 0; i < ARRAY_SIZE(dfa->tables); i++) {
178 kvfree(dfa->tables[i]);
179 dfa->tables[i] = NULL;
180 }
181 kfree(dfa);
182 }
183}
184
185/**
186 * aa_dfa_free_kref - free aa_dfa by kref (called by aa_put_dfa)
187 * @kr: kref callback for freeing of a dfa (NOT NULL)
188 */
189void aa_dfa_free_kref(struct kref *kref)
190{
191 struct aa_dfa *dfa = container_of(kref, struct aa_dfa, count);
192 dfa_free(dfa);
193}
194
195/**
196 * aa_dfa_unpack - unpack the binary tables of a serialized dfa
197 * @blob: aligned serialized stream of data to unpack (NOT NULL)
198 * @size: size of data to unpack
199 * @flags: flags controlling what type of accept tables are acceptable
200 *
201 * Unpack a dfa that has been serialized. To find information on the dfa
202 * format look in Documentation/security/apparmor.txt
203 * Assumes the dfa @blob stream has been aligned on a 8 byte boundary
204 *
205 * Returns: an unpacked dfa ready for matching or ERR_PTR on failure
206 */
207struct aa_dfa *aa_dfa_unpack(void *blob, size_t size, int flags)
208{
209 int hsize;
210 int error = -ENOMEM;
211 char *data = blob;
212 struct table_header *table = NULL;
213 struct aa_dfa *dfa = kzalloc(sizeof(struct aa_dfa), GFP_KERNEL);
214 if (!dfa)
215 goto fail;
216
217 kref_init(&dfa->count);
218
219 error = -EPROTO;
220
221 /* get dfa table set header */
222 if (size < sizeof(struct table_set_header))
223 goto fail;
224
225 if (ntohl(*(u32 *) data) != YYTH_MAGIC)
226 goto fail;
227
228 hsize = ntohl(*(u32 *) (data + 4));
229 if (size < hsize)
230 goto fail;
231
232 dfa->flags = ntohs(*(u16 *) (data + 12));
233 data += hsize;
234 size -= hsize;
235
236 while (size > 0) {
237 table = unpack_table(data, size);
238 if (!table)
239 goto fail;
240
241 switch (table->td_id) {
242 case YYTD_ID_ACCEPT:
243 if (!(table->td_flags & ACCEPT1_FLAGS(flags)))
244 goto fail;
245 break;
246 case YYTD_ID_ACCEPT2:
247 if (!(table->td_flags & ACCEPT2_FLAGS(flags)))
248 goto fail;
249 break;
250 case YYTD_ID_BASE:
251 if (table->td_flags != YYTD_DATA32)
252 goto fail;
253 break;
254 case YYTD_ID_DEF:
255 case YYTD_ID_NXT:
256 case YYTD_ID_CHK:
257 if (table->td_flags != YYTD_DATA16)
258 goto fail;
259 break;
260 case YYTD_ID_EC:
261 if (table->td_flags != YYTD_DATA8)
262 goto fail;
263 break;
264 default:
265 goto fail;
266 }
267 /* check for duplicate table entry */
268 if (dfa->tables[table->td_id])
269 goto fail;
270 dfa->tables[table->td_id] = table;
271 data += table_size(table->td_lolen, table->td_flags);
272 size -= table_size(table->td_lolen, table->td_flags);
273 table = NULL;
274 }
275
276 error = verify_dfa(dfa, flags);
277 if (error)
278 goto fail;
279
280 return dfa;
281
282fail:
283 kvfree(table);
284 dfa_free(dfa);
285 return ERR_PTR(error);
286}
287
288/**
289 * aa_dfa_match_len - traverse @dfa to find state @str stops at
290 * @dfa: the dfa to match @str against (NOT NULL)
291 * @start: the state of the dfa to start matching in
292 * @str: the string of bytes to match against the dfa (NOT NULL)
293 * @len: length of the string of bytes to match
294 *
295 * aa_dfa_match_len will match @str against the dfa and return the state it
296 * finished matching in. The final state can be used to look up the accepting
297 * label, or as the start state of a continuing match.
298 *
299 * This function will happily match again the 0 byte and only finishes
300 * when @len input is consumed.
301 *
302 * Returns: final state reached after input is consumed
303 */
304unsigned int aa_dfa_match_len(struct aa_dfa *dfa, unsigned int start,
305 const char *str, int len)
306{
307 u16 *def = DEFAULT_TABLE(dfa);
308 u32 *base = BASE_TABLE(dfa);
309 u16 *next = NEXT_TABLE(dfa);
310 u16 *check = CHECK_TABLE(dfa);
311 unsigned int state = start, pos;
312
313 if (state == 0)
314 return 0;
315
316 /* current state is <state>, matching character *str */
317 if (dfa->tables[YYTD_ID_EC]) {
318 /* Equivalence class table defined */
319 u8 *equiv = EQUIV_TABLE(dfa);
320 /* default is direct to next state */
321 for (; len; len--) {
322 pos = base_idx(base[state]) + equiv[(u8) *str++];
323 if (check[pos] == state)
324 state = next[pos];
325 else
326 state = def[state];
327 }
328 } else {
329 /* default is direct to next state */
330 for (; len; len--) {
331 pos = base_idx(base[state]) + (u8) *str++;
332 if (check[pos] == state)
333 state = next[pos];
334 else
335 state = def[state];
336 }
337 }
338
339 return state;
340}
341
342/**
343 * aa_dfa_match - traverse @dfa to find state @str stops at
344 * @dfa: the dfa to match @str against (NOT NULL)
345 * @start: the state of the dfa to start matching in
346 * @str: the null terminated string of bytes to match against the dfa (NOT NULL)
347 *
348 * aa_dfa_match will match @str against the dfa and return the state it
349 * finished matching in. The final state can be used to look up the accepting
350 * label, or as the start state of a continuing match.
351 *
352 * Returns: final state reached after input is consumed
353 */
354unsigned int aa_dfa_match(struct aa_dfa *dfa, unsigned int start,
355 const char *str)
356{
357 u16 *def = DEFAULT_TABLE(dfa);
358 u32 *base = BASE_TABLE(dfa);
359 u16 *next = NEXT_TABLE(dfa);
360 u16 *check = CHECK_TABLE(dfa);
361 unsigned int state = start, pos;
362
363 if (state == 0)
364 return 0;
365
366 /* current state is <state>, matching character *str */
367 if (dfa->tables[YYTD_ID_EC]) {
368 /* Equivalence class table defined */
369 u8 *equiv = EQUIV_TABLE(dfa);
370 /* default is direct to next state */
371 while (*str) {
372 pos = base_idx(base[state]) + equiv[(u8) *str++];
373 if (check[pos] == state)
374 state = next[pos];
375 else
376 state = def[state];
377 }
378 } else {
379 /* default is direct to next state */
380 while (*str) {
381 pos = base_idx(base[state]) + (u8) *str++;
382 if (check[pos] == state)
383 state = next[pos];
384 else
385 state = def[state];
386 }
387 }
388
389 return state;
390}
391
392/**
393 * aa_dfa_next - step one character to the next state in the dfa
394 * @dfa: the dfa to tranverse (NOT NULL)
395 * @state: the state to start in
396 * @c: the input character to transition on
397 *
398 * aa_dfa_match will step through the dfa by one input character @c
399 *
400 * Returns: state reach after input @c
401 */
402unsigned int aa_dfa_next(struct aa_dfa *dfa, unsigned int state,
403 const char c)
404{
405 u16 *def = DEFAULT_TABLE(dfa);
406 u32 *base = BASE_TABLE(dfa);
407 u16 *next = NEXT_TABLE(dfa);
408 u16 *check = CHECK_TABLE(dfa);
409 unsigned int pos;
410
411 /* current state is <state>, matching character *str */
412 if (dfa->tables[YYTD_ID_EC]) {
413 /* Equivalence class table defined */
414 u8 *equiv = EQUIV_TABLE(dfa);
415 /* default is direct to next state */
416
417 pos = base_idx(base[state]) + equiv[(u8) c];
418 if (check[pos] == state)
419 state = next[pos];
420 else
421 state = def[state];
422 } else {
423 /* default is direct to next state */
424 pos = base_idx(base[state]) + (u8) c;
425 if (check[pos] == state)
426 state = next[pos];
427 else
428 state = def[state];
429 }
430
431 return state;
432}