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 
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 
80 struct 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 
96 struct 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 
114 static 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 
119 struct aa_dfa *aa_dfa_unpack(void *blob, size_t size, int flags);
120 unsigned int aa_dfa_match_len(struct aa_dfa *dfa, unsigned int start,
121 			      const char *str, int len);
122 unsigned int aa_dfa_match(struct aa_dfa *dfa, unsigned int start,
123 			  const char *str);
124 unsigned int aa_dfa_next(struct aa_dfa *dfa, unsigned int state,
125 			 const char c);
126 
127 void 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  */
135 static 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