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
44 struct 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
81 struct 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
97 struct aa_dfa {
98 struct kref count;
99 u16 flags;
100 struct table_header *tables[YYTD_ID_TSIZE];
101 };
102
103 extern 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
table_size(size_t len,size_t el_size)117 static 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
122 int aa_setup_dfa_engine(void);
123 void aa_teardown_dfa_engine(void);
124
125 struct aa_dfa *aa_dfa_unpack(void *blob, size_t size, int flags);
126 unsigned int aa_dfa_match_len(struct aa_dfa *dfa, unsigned int start,
127 const char *str, int len);
128 unsigned int aa_dfa_match(struct aa_dfa *dfa, unsigned int start,
129 const char *str);
130 unsigned int aa_dfa_next(struct aa_dfa *dfa, unsigned int state,
131 const char c);
132
133 void 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 */
aa_get_dfa(struct aa_dfa * dfa)142 static 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 */
aa_put_dfa(struct aa_dfa * dfa)156 static 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 */
163