1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * AppArmor security module
4 *
5 * This file contains AppArmor policy dfa matching engine definitions.
6 *
7 * Copyright (C) 1998-2008 Novell/SUSE
8 * Copyright 2009-2012 Canonical Ltd.
9 */
10
11#ifndef __AA_MATCH_H
12#define __AA_MATCH_H
13
14#include <linux/kref.h>
15
16#define DFA_NOMATCH			0
17#define DFA_START			1
18
19
20/**
21 * The format used for transition tables is based on the GNU flex table
22 * file format (--tables-file option; see Table File Format in the flex
23 * info pages and the flex sources for documentation). The magic number
24 * used in the header is 0x1B5E783D instead of 0xF13C57B1 though, because
25 * new tables have been defined and others YY_ID_CHK (check) and YY_ID_DEF
26 * (default) tables are used slightly differently (see the apparmor-parser
27 * package).
28 *
29 *
30 * The data in the packed dfa is stored in network byte order, and the tables
31 * are arranged for flexibility.  We convert the table data to host native
32 * byte order.
33 *
34 * The dfa begins with a table set header, and is followed by the actual
35 * tables.
36 */
37
38#define YYTH_MAGIC	0x1B5E783D
39#define YYTH_FLAG_DIFF_ENCODE	1
40#define YYTH_FLAG_OOB_TRANS	2
41#define YYTH_FLAGS (YYTH_FLAG_DIFF_ENCODE | YYTH_FLAG_OOB_TRANS)
42
43#define MAX_OOB_SUPPORTED	1
44
45struct table_set_header {
46	u32 th_magic;		/* YYTH_MAGIC */
47	u32 th_hsize;
48	u32 th_ssize;
49	u16 th_flags;
50	char th_version[];
51};
52
53/* The YYTD_ID are one less than flex table mappings.  The flex id
54 * has 1 subtracted at table load time, this allows us to directly use the
55 * ID's as indexes.
56 */
57#define	YYTD_ID_ACCEPT	0
58#define YYTD_ID_BASE	1
59#define YYTD_ID_CHK	2
60#define YYTD_ID_DEF	3
61#define YYTD_ID_EC	4
62#define YYTD_ID_META	5
63#define YYTD_ID_ACCEPT2 6
64#define YYTD_ID_NXT	7
65#define YYTD_ID_TSIZE	8
66#define YYTD_ID_MAX	8
67
68#define YYTD_DATA8	1
69#define YYTD_DATA16	2
70#define YYTD_DATA32	4
71#define YYTD_DATA64	8
72
73/* ACCEPT & ACCEPT2 tables gets 6 dedicated flags, YYTD_DATAX define the
74 * first flags
75 */
76#define ACCEPT1_FLAGS(X) ((X) & 0x3f)
77#define ACCEPT2_FLAGS(X) ACCEPT1_FLAGS((X) >> YYTD_ID_ACCEPT2)
78#define TO_ACCEPT1_FLAG(X) ACCEPT1_FLAGS(X)
79#define TO_ACCEPT2_FLAG(X) (ACCEPT1_FLAGS(X) << YYTD_ID_ACCEPT2)
80#define DFA_FLAG_VERIFY_STATES 0x1000
81
82struct table_header {
83	u16 td_id;
84	u16 td_flags;
85	u32 td_hilen;
86	u32 td_lolen;
87	char td_data[];
88};
89
90#define DEFAULT_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_DEF]->td_data))
91#define BASE_TABLE(DFA) ((u32 *)((DFA)->tables[YYTD_ID_BASE]->td_data))
92#define NEXT_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_NXT]->td_data))
93#define CHECK_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_CHK]->td_data))
94#define EQUIV_TABLE(DFA) ((u8 *)((DFA)->tables[YYTD_ID_EC]->td_data))
95#define ACCEPT_TABLE(DFA) ((u32 *)((DFA)->tables[YYTD_ID_ACCEPT]->td_data))
96#define ACCEPT_TABLE2(DFA) ((u32 *)((DFA)->tables[YYTD_ID_ACCEPT2]->td_data))
97
98struct aa_dfa {
99	struct kref count;
100	u16 flags;
101	u32 max_oob;
102	struct table_header *tables[YYTD_ID_TSIZE];
103};
104
105extern struct aa_dfa *nulldfa;
106extern struct aa_dfa *stacksplitdfa;
107
108#define byte_to_byte(X) (X)
109
110#define UNPACK_ARRAY(TABLE, BLOB, LEN, TTYPE, BTYPE, NTOHX)	\
111	do { \
112		typeof(LEN) __i; \
113		TTYPE *__t = (TTYPE *) TABLE; \
114		BTYPE *__b = (BTYPE *) BLOB; \
115		for (__i = 0; __i < LEN; __i++) { \
116			__t[__i] = NTOHX(__b[__i]); \
117		} \
118	} while (0)
119
120static inline size_t table_size(size_t len, size_t el_size)
121{
122	return ALIGN(sizeof(struct table_header) + len * el_size, 8);
123}
124
125int aa_setup_dfa_engine(void);
126void aa_teardown_dfa_engine(void);
127
128struct aa_dfa *aa_dfa_unpack(void *blob, size_t size, int flags);
129unsigned int aa_dfa_match_len(struct aa_dfa *dfa, unsigned int start,
130			      const char *str, int len);
131unsigned int aa_dfa_match(struct aa_dfa *dfa, unsigned int start,
132			  const char *str);
133unsigned int aa_dfa_next(struct aa_dfa *dfa, unsigned int state,
134			 const char c);
135unsigned int aa_dfa_outofband_transition(struct aa_dfa *dfa,
136					 unsigned int state);
137unsigned int aa_dfa_match_until(struct aa_dfa *dfa, unsigned int start,
138				const char *str, const char **retpos);
139unsigned int aa_dfa_matchn_until(struct aa_dfa *dfa, unsigned int start,
140				 const char *str, int n, const char **retpos);
141
142void aa_dfa_free_kref(struct kref *kref);
143
144#define WB_HISTORY_SIZE 24
145struct match_workbuf {
146	unsigned int count;
147	unsigned int pos;
148	unsigned int len;
149	unsigned int size;	/* power of 2, same as history size */
150	unsigned int history[WB_HISTORY_SIZE];
151};
152#define DEFINE_MATCH_WB(N)		\
153struct match_workbuf N = {		\
154	.count = 0,			\
155	.pos = 0,			\
156	.len = 0,			\
157}
158
159unsigned int aa_dfa_leftmatch(struct aa_dfa *dfa, unsigned int start,
160			      const char *str, unsigned int *count);
161
162/**
163 * aa_get_dfa - increment refcount on dfa @p
164 * @dfa: dfa  (MAYBE NULL)
165 *
166 * Returns: pointer to @dfa if @dfa is NULL will return NULL
167 * Requires: @dfa must be held with valid refcount when called
168 */
169static inline struct aa_dfa *aa_get_dfa(struct aa_dfa *dfa)
170{
171	if (dfa)
172		kref_get(&(dfa->count));
173
174	return dfa;
175}
176
177/**
178 * aa_put_dfa - put a dfa refcount
179 * @dfa: dfa to put refcount   (MAYBE NULL)
180 *
181 * Requires: if @dfa != NULL that a valid refcount be held
182 */
183static inline void aa_put_dfa(struct aa_dfa *dfa)
184{
185	if (dfa)
186		kref_put(&dfa->count, aa_dfa_free_kref);
187}
188
189#define MATCH_FLAG_DIFF_ENCODE 0x80000000
190#define MARK_DIFF_ENCODE 0x40000000
191#define MATCH_FLAG_OOB_TRANSITION 0x20000000
192#define MATCH_FLAGS_MASK 0xff000000
193#define MATCH_FLAGS_VALID (MATCH_FLAG_DIFF_ENCODE | MATCH_FLAG_OOB_TRANSITION)
194#define MATCH_FLAGS_INVALID (MATCH_FLAGS_MASK & ~MATCH_FLAGS_VALID)
195
196#endif /* __AA_MATCH_H */
197