1/*
2 * AppArmor security module
3 *
4 * This file contains AppArmor policy dfa matching engine definitions.
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#ifndef __AA_MATCH_H
16#define __AA_MATCH_H
17
18#include <linux/kref.h>
19
20#define DFA_NOMATCH			0
21#define DFA_START			1
22
23
24/**
25 * The format used for transition tables is based on the GNU flex table
26 * file format (--tables-file option; see Table File Format in the flex
27 * info pages and the flex sources for documentation). The magic number
28 * used in the header is 0x1B5E783D instead of 0xF13C57B1 though, because
29 * new tables have been defined and others YY_ID_CHK (check) and YY_ID_DEF
30 * (default) tables are used slightly differently (see the apparmor-parser
31 * package).
32 *
33 *
34 * The data in the packed dfa is stored in network byte order, and the tables
35 * are arranged for flexibility.  We convert the table data to host native
36 * byte order.
37 *
38 * The dfa begins with a table set header, and is followed by the actual
39 * tables.
40 */
41
42#define YYTH_MAGIC	0x1B5E783D
43
44struct table_set_header {
45	u32 th_magic;		/* YYTH_MAGIC */
46	u32 th_hsize;
47	u32 th_ssize;
48	u16 th_flags;
49	char th_version[];
50};
51
52/* The YYTD_ID are one less than flex table mappings.  The flex id
53 * has 1 subtracted at table load time, this allows us to directly use the
54 * ID's as indexes.
55 */
56#define	YYTD_ID_ACCEPT	0
57#define YYTD_ID_BASE	1
58#define YYTD_ID_CHK	2
59#define YYTD_ID_DEF	3
60#define YYTD_ID_EC	4
61#define YYTD_ID_META	5
62#define YYTD_ID_ACCEPT2 6
63#define YYTD_ID_NXT	7
64#define YYTD_ID_TSIZE	8
65
66#define YYTD_DATA8	1
67#define YYTD_DATA16	2
68#define YYTD_DATA32	4
69#define YYTD_DATA64	8
70
71/* ACCEPT & ACCEPT2 tables gets 6 dedicated flags, YYTD_DATAX define the
72 * first flags
73 */
74#define ACCEPT1_FLAGS(X) ((X) & 0x3f)
75#define ACCEPT2_FLAGS(X) ACCEPT1_FLAGS((X) >> YYTD_ID_ACCEPT2)
76#define TO_ACCEPT1_FLAG(X) ACCEPT1_FLAGS(X)
77#define TO_ACCEPT2_FLAG(X) (ACCEPT1_FLAGS(X) << YYTD_ID_ACCEPT2)
78#define DFA_FLAG_VERIFY_STATES 0x1000
79
80struct table_header {
81	u16 td_id;
82	u16 td_flags;
83	u32 td_hilen;
84	u32 td_lolen;
85	char td_data[];
86};
87
88#define DEFAULT_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_DEF]->td_data))
89#define BASE_TABLE(DFA) ((u32 *)((DFA)->tables[YYTD_ID_BASE]->td_data))
90#define NEXT_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_NXT]->td_data))
91#define CHECK_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_CHK]->td_data))
92#define EQUIV_TABLE(DFA) ((u8 *)((DFA)->tables[YYTD_ID_EC]->td_data))
93#define ACCEPT_TABLE(DFA) ((u32 *)((DFA)->tables[YYTD_ID_ACCEPT]->td_data))
94#define ACCEPT_TABLE2(DFA) ((u32 *)((DFA)->tables[YYTD_ID_ACCEPT2]->td_data))
95
96struct aa_dfa {
97	struct kref count;
98	u16 flags;
99	struct table_header *tables[YYTD_ID_TSIZE];
100};
101
102#define byte_to_byte(X) (X)
103
104#define UNPACK_ARRAY(TABLE, BLOB, LEN, TYPE, NTOHX) \
105	do { \
106		typeof(LEN) __i; \
107		TYPE *__t = (TYPE *) TABLE; \
108		TYPE *__b = (TYPE *) BLOB; \
109		for (__i = 0; __i < LEN; __i++) { \
110			__t[__i] = NTOHX(__b[__i]); \
111		} \
112	} while (0)
113
114static inline size_t table_size(size_t len, size_t el_size)
115{
116	return ALIGN(sizeof(struct table_header) + len * el_size, 8);
117}
118
119struct aa_dfa *aa_dfa_unpack(void *blob, size_t size, int flags);
120unsigned int aa_dfa_match_len(struct aa_dfa *dfa, unsigned int start,
121			      const char *str, int len);
122unsigned int aa_dfa_match(struct aa_dfa *dfa, unsigned int start,
123			  const char *str);
124unsigned int aa_dfa_next(struct aa_dfa *dfa, unsigned int state,
125			 const char c);
126
127void aa_dfa_free_kref(struct kref *kref);
128
129/**
130 * aa_put_dfa - put a dfa refcount
131 * @dfa: dfa to put refcount   (MAYBE NULL)
132 *
133 * Requires: if @dfa != NULL that a valid refcount be held
134 */
135static inline void aa_put_dfa(struct aa_dfa *dfa)
136{
137	if (dfa)
138		kref_put(&dfa->count, aa_dfa_free_kref);
139}
140
141#endif /* __AA_MATCH_H */
142