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
24 static char nulldfa_src[] = {
25 #include "nulldfa.in"
26 };
27 struct aa_dfa *nulldfa;
28
29 static char stacksplitdfa_src[] = {
30 #include "stacksplitdfa.in"
31 };
32 struct aa_dfa *stacksplitdfa;
33
aa_setup_dfa_engine(void)34 int 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
aa_teardown_dfa_engine(void)62 void 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 */
unpack_table(char * blob,size_t bsize)77 static 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
130 out:
131 return table;
132 fail:
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 */
verify_table_headers(struct table_header ** tables,int flags)147 static 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;
184 out:
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 */
verify_dfa(struct aa_dfa * dfa)197 static 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_idx(BASE_TABLE(dfa)[i]) + 255 >= trans_count) {
211 pr_err("AppArmor DFA next/check upper bounds error\n");
212 goto out;
213 }
214 }
215
216 for (i = 0; i < trans_count; i++) {
217 if (NEXT_TABLE(dfa)[i] >= state_count)
218 goto out;
219 if (CHECK_TABLE(dfa)[i] >= state_count)
220 goto out;
221 }
222
223 /* Now that all the other tables are verified, verify diffencoding */
224 for (i = 0; i < state_count; i++) {
225 size_t j, k;
226
227 for (j = i;
228 (BASE_TABLE(dfa)[j] & MATCH_FLAG_DIFF_ENCODE) &&
229 !(BASE_TABLE(dfa)[j] & MARK_DIFF_ENCODE);
230 j = k) {
231 k = DEFAULT_TABLE(dfa)[j];
232 if (j == k)
233 goto out;
234 if (k < j)
235 break; /* already verified */
236 BASE_TABLE(dfa)[j] |= MARK_DIFF_ENCODE;
237 }
238 }
239 error = 0;
240
241 out:
242 return error;
243 }
244
245 /**
246 * dfa_free - free a dfa allocated by aa_dfa_unpack
247 * @dfa: the dfa to free (MAYBE NULL)
248 *
249 * Requires: reference count to dfa == 0
250 */
dfa_free(struct aa_dfa * dfa)251 static void dfa_free(struct aa_dfa *dfa)
252 {
253 if (dfa) {
254 int i;
255
256 for (i = 0; i < ARRAY_SIZE(dfa->tables); i++) {
257 kvfree(dfa->tables[i]);
258 dfa->tables[i] = NULL;
259 }
260 kfree(dfa);
261 }
262 }
263
264 /**
265 * aa_dfa_free_kref - free aa_dfa by kref (called by aa_put_dfa)
266 * @kr: kref callback for freeing of a dfa (NOT NULL)
267 */
aa_dfa_free_kref(struct kref * kref)268 void aa_dfa_free_kref(struct kref *kref)
269 {
270 struct aa_dfa *dfa = container_of(kref, struct aa_dfa, count);
271 dfa_free(dfa);
272 }
273
274 /**
275 * aa_dfa_unpack - unpack the binary tables of a serialized dfa
276 * @blob: aligned serialized stream of data to unpack (NOT NULL)
277 * @size: size of data to unpack
278 * @flags: flags controlling what type of accept tables are acceptable
279 *
280 * Unpack a dfa that has been serialized. To find information on the dfa
281 * format look in Documentation/admin-guide/LSM/apparmor.rst
282 * Assumes the dfa @blob stream has been aligned on a 8 byte boundary
283 *
284 * Returns: an unpacked dfa ready for matching or ERR_PTR on failure
285 */
aa_dfa_unpack(void * blob,size_t size,int flags)286 struct aa_dfa *aa_dfa_unpack(void *blob, size_t size, int flags)
287 {
288 int hsize;
289 int error = -ENOMEM;
290 char *data = blob;
291 struct table_header *table = NULL;
292 struct aa_dfa *dfa = kzalloc(sizeof(struct aa_dfa), GFP_KERNEL);
293 if (!dfa)
294 goto fail;
295
296 kref_init(&dfa->count);
297
298 error = -EPROTO;
299
300 /* get dfa table set header */
301 if (size < sizeof(struct table_set_header))
302 goto fail;
303
304 if (ntohl(*(__be32 *) data) != YYTH_MAGIC)
305 goto fail;
306
307 hsize = ntohl(*(__be32 *) (data + 4));
308 if (size < hsize)
309 goto fail;
310
311 dfa->flags = ntohs(*(__be16 *) (data + 12));
312 if (dfa->flags != 0 && dfa->flags != YYTH_FLAG_DIFF_ENCODE)
313 goto fail;
314
315 data += hsize;
316 size -= hsize;
317
318 while (size > 0) {
319 table = unpack_table(data, size);
320 if (!table)
321 goto fail;
322
323 switch (table->td_id) {
324 case YYTD_ID_ACCEPT:
325 if (!(table->td_flags & ACCEPT1_FLAGS(flags)))
326 goto fail;
327 break;
328 case YYTD_ID_ACCEPT2:
329 if (!(table->td_flags & ACCEPT2_FLAGS(flags)))
330 goto fail;
331 break;
332 case YYTD_ID_BASE:
333 if (table->td_flags != YYTD_DATA32)
334 goto fail;
335 break;
336 case YYTD_ID_DEF:
337 case YYTD_ID_NXT:
338 case YYTD_ID_CHK:
339 if (table->td_flags != YYTD_DATA16)
340 goto fail;
341 break;
342 case YYTD_ID_EC:
343 if (table->td_flags != YYTD_DATA8)
344 goto fail;
345 break;
346 default:
347 goto fail;
348 }
349 /* check for duplicate table entry */
350 if (dfa->tables[table->td_id])
351 goto fail;
352 dfa->tables[table->td_id] = table;
353 data += table_size(table->td_lolen, table->td_flags);
354 size -= table_size(table->td_lolen, table->td_flags);
355 table = NULL;
356 }
357 error = verify_table_headers(dfa->tables, flags);
358 if (error)
359 goto fail;
360
361 if (flags & DFA_FLAG_VERIFY_STATES) {
362 error = verify_dfa(dfa);
363 if (error)
364 goto fail;
365 }
366
367 return dfa;
368
369 fail:
370 kvfree(table);
371 dfa_free(dfa);
372 return ERR_PTR(error);
373 }
374
375 #define match_char(state, def, base, next, check, C) \
376 do { \
377 u32 b = (base)[(state)]; \
378 unsigned int pos = base_idx(b) + (C); \
379 if ((check)[pos] != (state)) { \
380 (state) = (def)[(state)]; \
381 if (b & MATCH_FLAG_DIFF_ENCODE) \
382 continue; \
383 break; \
384 } \
385 (state) = (next)[pos]; \
386 break; \
387 } while (1)
388
389 /**
390 * aa_dfa_match_len - traverse @dfa to find state @str stops at
391 * @dfa: the dfa to match @str against (NOT NULL)
392 * @start: the state of the dfa to start matching in
393 * @str: the string of bytes to match against the dfa (NOT NULL)
394 * @len: length of the string of bytes to match
395 *
396 * aa_dfa_match_len will match @str against the dfa and return the state it
397 * finished matching in. The final state can be used to look up the accepting
398 * label, or as the start state of a continuing match.
399 *
400 * This function will happily match again the 0 byte and only finishes
401 * when @len input is consumed.
402 *
403 * Returns: final state reached after input is consumed
404 */
aa_dfa_match_len(struct aa_dfa * dfa,unsigned int start,const char * str,int len)405 unsigned int aa_dfa_match_len(struct aa_dfa *dfa, unsigned int start,
406 const char *str, int len)
407 {
408 u16 *def = DEFAULT_TABLE(dfa);
409 u32 *base = BASE_TABLE(dfa);
410 u16 *next = NEXT_TABLE(dfa);
411 u16 *check = CHECK_TABLE(dfa);
412 unsigned int state = start;
413
414 if (state == 0)
415 return 0;
416
417 /* current state is <state>, matching character *str */
418 if (dfa->tables[YYTD_ID_EC]) {
419 /* Equivalence class table defined */
420 u8 *equiv = EQUIV_TABLE(dfa);
421 for (; len; len--)
422 match_char(state, def, base, next, check,
423 equiv[(u8) *str++]);
424 } else {
425 /* default is direct to next state */
426 for (; len; len--)
427 match_char(state, def, base, next, check, (u8) *str++);
428 }
429
430 return state;
431 }
432
433 /**
434 * aa_dfa_match - traverse @dfa to find state @str stops at
435 * @dfa: the dfa to match @str against (NOT NULL)
436 * @start: the state of the dfa to start matching in
437 * @str: the null terminated string of bytes to match against the dfa (NOT NULL)
438 *
439 * aa_dfa_match will match @str against the dfa and return the state it
440 * finished matching in. The final state can be used to look up the accepting
441 * label, or as the start state of a continuing match.
442 *
443 * Returns: final state reached after input is consumed
444 */
aa_dfa_match(struct aa_dfa * dfa,unsigned int start,const char * str)445 unsigned int aa_dfa_match(struct aa_dfa *dfa, unsigned int start,
446 const char *str)
447 {
448 u16 *def = DEFAULT_TABLE(dfa);
449 u32 *base = BASE_TABLE(dfa);
450 u16 *next = NEXT_TABLE(dfa);
451 u16 *check = CHECK_TABLE(dfa);
452 unsigned int state = start;
453
454 if (state == 0)
455 return 0;
456
457 /* current state is <state>, matching character *str */
458 if (dfa->tables[YYTD_ID_EC]) {
459 /* Equivalence class table defined */
460 u8 *equiv = EQUIV_TABLE(dfa);
461 /* default is direct to next state */
462 while (*str)
463 match_char(state, def, base, next, check,
464 equiv[(u8) *str++]);
465 } else {
466 /* default is direct to next state */
467 while (*str)
468 match_char(state, def, base, next, check, (u8) *str++);
469 }
470
471 return state;
472 }
473
474 /**
475 * aa_dfa_next - step one character to the next state in the dfa
476 * @dfa: the dfa to traverse (NOT NULL)
477 * @state: the state to start in
478 * @c: the input character to transition on
479 *
480 * aa_dfa_match will step through the dfa by one input character @c
481 *
482 * Returns: state reach after input @c
483 */
aa_dfa_next(struct aa_dfa * dfa,unsigned int state,const char c)484 unsigned int aa_dfa_next(struct aa_dfa *dfa, unsigned int state,
485 const char c)
486 {
487 u16 *def = DEFAULT_TABLE(dfa);
488 u32 *base = BASE_TABLE(dfa);
489 u16 *next = NEXT_TABLE(dfa);
490 u16 *check = CHECK_TABLE(dfa);
491
492 /* current state is <state>, matching character *str */
493 if (dfa->tables[YYTD_ID_EC]) {
494 /* Equivalence class table defined */
495 u8 *equiv = EQUIV_TABLE(dfa);
496 match_char(state, def, base, next, check, equiv[(u8) c]);
497 } else
498 match_char(state, def, base, next, check, (u8) c);
499
500 return state;
501 }
502
503 /**
504 * aa_dfa_match_until - traverse @dfa until accept state or end of input
505 * @dfa: the dfa to match @str against (NOT NULL)
506 * @start: the state of the dfa to start matching in
507 * @str: the null terminated string of bytes to match against the dfa (NOT NULL)
508 * @retpos: first character in str after match OR end of string
509 *
510 * aa_dfa_match will match @str against the dfa and return the state it
511 * finished matching in. The final state can be used to look up the accepting
512 * label, or as the start state of a continuing match.
513 *
514 * Returns: final state reached after input is consumed
515 */
aa_dfa_match_until(struct aa_dfa * dfa,unsigned int start,const char * str,const char ** retpos)516 unsigned int aa_dfa_match_until(struct aa_dfa *dfa, unsigned int start,
517 const char *str, const char **retpos)
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 u32 *accept = ACCEPT_TABLE(dfa);
524 unsigned int state = start, pos;
525
526 if (state == 0)
527 return 0;
528
529 /* current state is <state>, matching character *str */
530 if (dfa->tables[YYTD_ID_EC]) {
531 /* Equivalence class table defined */
532 u8 *equiv = EQUIV_TABLE(dfa);
533 /* default is direct to next state */
534 while (*str) {
535 pos = base_idx(base[state]) + equiv[(u8) *str++];
536 if (check[pos] == state)
537 state = next[pos];
538 else
539 state = def[state];
540 if (accept[state])
541 break;
542 }
543 } else {
544 /* default is direct to next state */
545 while (*str) {
546 pos = base_idx(base[state]) + (u8) *str++;
547 if (check[pos] == state)
548 state = next[pos];
549 else
550 state = def[state];
551 if (accept[state])
552 break;
553 }
554 }
555
556 *retpos = str;
557 return state;
558 }
559
560 /**
561 * aa_dfa_matchn_until - traverse @dfa until accept or @n bytes consumed
562 * @dfa: the dfa to match @str against (NOT NULL)
563 * @start: the state of the dfa to start matching in
564 * @str: the string of bytes to match against the dfa (NOT NULL)
565 * @n: length of the string of bytes to match
566 * @retpos: first character in str after match OR str + n
567 *
568 * aa_dfa_match_len will match @str against the dfa and return the state it
569 * finished matching in. The final state can be used to look up the accepting
570 * label, or as the start state of a continuing match.
571 *
572 * This function will happily match again the 0 byte and only finishes
573 * when @n input is consumed.
574 *
575 * Returns: final state reached after input is consumed
576 */
aa_dfa_matchn_until(struct aa_dfa * dfa,unsigned int start,const char * str,int n,const char ** retpos)577 unsigned int aa_dfa_matchn_until(struct aa_dfa *dfa, unsigned int start,
578 const char *str, int n, const char **retpos)
579 {
580 u16 *def = DEFAULT_TABLE(dfa);
581 u32 *base = BASE_TABLE(dfa);
582 u16 *next = NEXT_TABLE(dfa);
583 u16 *check = CHECK_TABLE(dfa);
584 u32 *accept = ACCEPT_TABLE(dfa);
585 unsigned int state = start, pos;
586
587 *retpos = NULL;
588 if (state == 0)
589 return 0;
590
591 /* current state is <state>, matching character *str */
592 if (dfa->tables[YYTD_ID_EC]) {
593 /* Equivalence class table defined */
594 u8 *equiv = EQUIV_TABLE(dfa);
595 /* default is direct to next state */
596 for (; n; n--) {
597 pos = base_idx(base[state]) + equiv[(u8) *str++];
598 if (check[pos] == state)
599 state = next[pos];
600 else
601 state = def[state];
602 if (accept[state])
603 break;
604 }
605 } else {
606 /* default is direct to next state */
607 for (; n; n--) {
608 pos = base_idx(base[state]) + (u8) *str++;
609 if (check[pos] == state)
610 state = next[pos];
611 else
612 state = def[state];
613 if (accept[state])
614 break;
615 }
616 }
617
618 *retpos = str;
619 return state;
620 }
621
622 #define inc_wb_pos(wb) \
623 do { \
624 wb->pos = (wb->pos + 1) & (wb->size - 1); \
625 wb->len = (wb->len + 1) & (wb->size - 1); \
626 } while (0)
627
628 /* For DFAs that don't support extended tagging of states */
is_loop(struct match_workbuf * wb,unsigned int state,unsigned int * adjust)629 static bool is_loop(struct match_workbuf *wb, unsigned int state,
630 unsigned int *adjust)
631 {
632 unsigned int pos = wb->pos;
633 unsigned int i;
634
635 if (wb->history[pos] < state)
636 return false;
637
638 for (i = 0; i <= wb->len; i++) {
639 if (wb->history[pos] == state) {
640 *adjust = i;
641 return true;
642 }
643 if (pos == 0)
644 pos = wb->size;
645 pos--;
646 }
647
648 *adjust = i;
649 return true;
650 }
651
leftmatch_fb(struct aa_dfa * dfa,unsigned int start,const char * str,struct match_workbuf * wb,unsigned int * count)652 static unsigned int leftmatch_fb(struct aa_dfa *dfa, unsigned int start,
653 const char *str, struct match_workbuf *wb,
654 unsigned int *count)
655 {
656 u16 *def = DEFAULT_TABLE(dfa);
657 u32 *base = BASE_TABLE(dfa);
658 u16 *next = NEXT_TABLE(dfa);
659 u16 *check = CHECK_TABLE(dfa);
660 unsigned int state = start, pos;
661
662 AA_BUG(!dfa);
663 AA_BUG(!str);
664 AA_BUG(!wb);
665 AA_BUG(!count);
666
667 *count = 0;
668 if (state == 0)
669 return 0;
670
671 /* current state is <state>, matching character *str */
672 if (dfa->tables[YYTD_ID_EC]) {
673 /* Equivalence class table defined */
674 u8 *equiv = EQUIV_TABLE(dfa);
675 /* default is direct to next state */
676 while (*str) {
677 unsigned int adjust;
678
679 wb->history[wb->pos] = state;
680 pos = base_idx(base[state]) + equiv[(u8) *str++];
681 if (check[pos] == state)
682 state = next[pos];
683 else
684 state = def[state];
685 if (is_loop(wb, state, &adjust)) {
686 state = aa_dfa_match(dfa, state, str);
687 *count -= adjust;
688 goto out;
689 }
690 inc_wb_pos(wb);
691 (*count)++;
692 }
693 } else {
694 /* default is direct to next state */
695 while (*str) {
696 unsigned int adjust;
697
698 wb->history[wb->pos] = state;
699 pos = base_idx(base[state]) + (u8) *str++;
700 if (check[pos] == state)
701 state = next[pos];
702 else
703 state = def[state];
704 if (is_loop(wb, state, &adjust)) {
705 state = aa_dfa_match(dfa, state, str);
706 *count -= adjust;
707 goto out;
708 }
709 inc_wb_pos(wb);
710 (*count)++;
711 }
712 }
713
714 out:
715 if (!state)
716 *count = 0;
717 return state;
718 }
719
720 /**
721 * aa_dfa_leftmatch - traverse @dfa to find state @str stops at
722 * @dfa: the dfa to match @str against (NOT NULL)
723 * @start: the state of the dfa to start matching in
724 * @str: the null terminated string of bytes to match against the dfa (NOT NULL)
725 * @count: current count of longest left.
726 *
727 * aa_dfa_match will match @str against the dfa and return the state it
728 * finished matching in. The final state can be used to look up the accepting
729 * label, or as the start state of a continuing match.
730 *
731 * Returns: final state reached after input is consumed
732 */
aa_dfa_leftmatch(struct aa_dfa * dfa,unsigned int start,const char * str,unsigned int * count)733 unsigned int aa_dfa_leftmatch(struct aa_dfa *dfa, unsigned int start,
734 const char *str, unsigned int *count)
735 {
736 DEFINE_MATCH_WB(wb);
737
738 /* TODO: match for extended state dfas */
739
740 return leftmatch_fb(dfa, start, str, &wb, count);
741 }
742