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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#define YYTD_ID_MAX 8
66
67#define YYTD_DATA8 1
68#define YYTD_DATA16 2
69#define YYTD_DATA32 4
70#define YYTD_DATA64 8
71
72/* ACCEPT & ACCEPT2 tables gets 6 dedicated flags, YYTD_DATAX define the
73 * first flags
74 */
75#define ACCEPT1_FLAGS(X) ((X) & 0x3f)
76#define ACCEPT2_FLAGS(X) ACCEPT1_FLAGS((X) >> YYTD_ID_ACCEPT2)
77#define TO_ACCEPT1_FLAG(X) ACCEPT1_FLAGS(X)
78#define TO_ACCEPT2_FLAG(X) (ACCEPT1_FLAGS(X) << YYTD_ID_ACCEPT2)
79#define DFA_FLAG_VERIFY_STATES 0x1000
80
81struct table_header {
82 u16 td_id;
83 u16 td_flags;
84 u32 td_hilen;
85 u32 td_lolen;
86 char td_data[];
87};
88
89#define DEFAULT_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_DEF]->td_data))
90#define BASE_TABLE(DFA) ((u32 *)((DFA)->tables[YYTD_ID_BASE]->td_data))
91#define NEXT_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_NXT]->td_data))
92#define CHECK_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_CHK]->td_data))
93#define EQUIV_TABLE(DFA) ((u8 *)((DFA)->tables[YYTD_ID_EC]->td_data))
94#define ACCEPT_TABLE(DFA) ((u32 *)((DFA)->tables[YYTD_ID_ACCEPT]->td_data))
95#define ACCEPT_TABLE2(DFA) ((u32 *)((DFA)->tables[YYTD_ID_ACCEPT2]->td_data))
96
97struct aa_dfa {
98 struct kref count;
99 u16 flags;
100 struct table_header *tables[YYTD_ID_TSIZE];
101};
102
103extern struct aa_dfa *nulldfa;
104
105#define byte_to_byte(X) (X)
106
107#define UNPACK_ARRAY(TABLE, BLOB, LEN, TTYPE, BTYPE, NTOHX) \
108 do { \
109 typeof(LEN) __i; \
110 TTYPE *__t = (TTYPE *) TABLE; \
111 BTYPE *__b = (BTYPE *) BLOB; \
112 for (__i = 0; __i < LEN; __i++) { \
113 __t[__i] = NTOHX(__b[__i]); \
114 } \
115 } while (0)
116
117static inline size_t table_size(size_t len, size_t el_size)
118{
119 return ALIGN(sizeof(struct table_header) + len * el_size, 8);
120}
121
122int aa_setup_dfa_engine(void);
123void aa_teardown_dfa_engine(void);
124
125struct aa_dfa *aa_dfa_unpack(void *blob, size_t size, int flags);
126unsigned int aa_dfa_match_len(struct aa_dfa *dfa, unsigned int start,
127 const char *str, int len);
128unsigned int aa_dfa_match(struct aa_dfa *dfa, unsigned int start,
129 const char *str);
130unsigned int aa_dfa_next(struct aa_dfa *dfa, unsigned int state,
131 const char c);
132
133void aa_dfa_free_kref(struct kref *kref);
134
135/**
136 * aa_get_dfa - increment refcount on dfa @p
137 * @dfa: dfa (MAYBE NULL)
138 *
139 * Returns: pointer to @dfa if @dfa is NULL will return NULL
140 * Requires: @dfa must be held with valid refcount when called
141 */
142static inline struct aa_dfa *aa_get_dfa(struct aa_dfa *dfa)
143{
144 if (dfa)
145 kref_get(&(dfa->count));
146
147 return dfa;
148}
149
150/**
151 * aa_put_dfa - put a dfa refcount
152 * @dfa: dfa to put refcount (MAYBE NULL)
153 *
154 * Requires: if @dfa != NULL that a valid refcount be held
155 */
156static inline void aa_put_dfa(struct aa_dfa *dfa)
157{
158 if (dfa)
159 kref_put(&dfa->count, aa_dfa_free_kref);
160}
161
162#endif /* __AA_MATCH_H */