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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
41struct table_set_header {
42 u32 th_magic; /* YYTH_MAGIC */
43 u32 th_hsize;
44 u32 th_ssize;
45 u16 th_flags;
46 char th_version[];
47};
48
49/* The YYTD_ID are one less than flex table mappings. The flex id
50 * has 1 subtracted at table load time, this allows us to directly use the
51 * ID's as indexes.
52 */
53#define YYTD_ID_ACCEPT 0
54#define YYTD_ID_BASE 1
55#define YYTD_ID_CHK 2
56#define YYTD_ID_DEF 3
57#define YYTD_ID_EC 4
58#define YYTD_ID_META 5
59#define YYTD_ID_ACCEPT2 6
60#define YYTD_ID_NXT 7
61#define YYTD_ID_TSIZE 8
62#define YYTD_ID_MAX 8
63
64#define YYTD_DATA8 1
65#define YYTD_DATA16 2
66#define YYTD_DATA32 4
67#define YYTD_DATA64 8
68
69/* ACCEPT & ACCEPT2 tables gets 6 dedicated flags, YYTD_DATAX define the
70 * first flags
71 */
72#define ACCEPT1_FLAGS(X) ((X) & 0x3f)
73#define ACCEPT2_FLAGS(X) ACCEPT1_FLAGS((X) >> YYTD_ID_ACCEPT2)
74#define TO_ACCEPT1_FLAG(X) ACCEPT1_FLAGS(X)
75#define TO_ACCEPT2_FLAG(X) (ACCEPT1_FLAGS(X) << YYTD_ID_ACCEPT2)
76#define DFA_FLAG_VERIFY_STATES 0x1000
77
78struct table_header {
79 u16 td_id;
80 u16 td_flags;
81 u32 td_hilen;
82 u32 td_lolen;
83 char td_data[];
84};
85
86#define DEFAULT_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_DEF]->td_data))
87#define BASE_TABLE(DFA) ((u32 *)((DFA)->tables[YYTD_ID_BASE]->td_data))
88#define NEXT_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_NXT]->td_data))
89#define CHECK_TABLE(DFA) ((u16 *)((DFA)->tables[YYTD_ID_CHK]->td_data))
90#define EQUIV_TABLE(DFA) ((u8 *)((DFA)->tables[YYTD_ID_EC]->td_data))
91#define ACCEPT_TABLE(DFA) ((u32 *)((DFA)->tables[YYTD_ID_ACCEPT]->td_data))
92#define ACCEPT_TABLE2(DFA) ((u32 *)((DFA)->tables[YYTD_ID_ACCEPT2]->td_data))
93
94struct aa_dfa {
95 struct kref count;
96 u16 flags;
97 struct table_header *tables[YYTD_ID_TSIZE];
98};
99
100extern struct aa_dfa *nulldfa;
101extern struct aa_dfa *stacksplitdfa;
102
103#define byte_to_byte(X) (X)
104
105#define UNPACK_ARRAY(TABLE, BLOB, LEN, TTYPE, BTYPE, NTOHX) \
106 do { \
107 typeof(LEN) __i; \
108 TTYPE *__t = (TTYPE *) TABLE; \
109 BTYPE *__b = (BTYPE *) BLOB; \
110 for (__i = 0; __i < LEN; __i++) { \
111 __t[__i] = NTOHX(__b[__i]); \
112 } \
113 } while (0)
114
115static inline size_t table_size(size_t len, size_t el_size)
116{
117 return ALIGN(sizeof(struct table_header) + len * el_size, 8);
118}
119
120int aa_setup_dfa_engine(void);
121void aa_teardown_dfa_engine(void);
122
123struct aa_dfa *aa_dfa_unpack(void *blob, size_t size, int flags);
124unsigned int aa_dfa_match_len(struct aa_dfa *dfa, unsigned int start,
125 const char *str, int len);
126unsigned int aa_dfa_match(struct aa_dfa *dfa, unsigned int start,
127 const char *str);
128unsigned int aa_dfa_next(struct aa_dfa *dfa, unsigned int state,
129 const char c);
130unsigned int aa_dfa_match_until(struct aa_dfa *dfa, unsigned int start,
131 const char *str, const char **retpos);
132unsigned int aa_dfa_matchn_until(struct aa_dfa *dfa, unsigned int start,
133 const char *str, int n, const char **retpos);
134
135void aa_dfa_free_kref(struct kref *kref);
136
137#define WB_HISTORY_SIZE 8
138struct match_workbuf {
139 unsigned int count;
140 unsigned int pos;
141 unsigned int len;
142 unsigned int size; /* power of 2, same as history size */
143 unsigned int history[WB_HISTORY_SIZE];
144};
145#define DEFINE_MATCH_WB(N) \
146struct match_workbuf N = { \
147 .count = 0, \
148 .pos = 0, \
149 .len = 0, \
150 .size = WB_HISTORY_SIZE, \
151}
152
153unsigned int aa_dfa_leftmatch(struct aa_dfa *dfa, unsigned int start,
154 const char *str, unsigned int *count);
155
156/**
157 * aa_get_dfa - increment refcount on dfa @p
158 * @dfa: dfa (MAYBE NULL)
159 *
160 * Returns: pointer to @dfa if @dfa is NULL will return NULL
161 * Requires: @dfa must be held with valid refcount when called
162 */
163static inline struct aa_dfa *aa_get_dfa(struct aa_dfa *dfa)
164{
165 if (dfa)
166 kref_get(&(dfa->count));
167
168 return dfa;
169}
170
171/**
172 * aa_put_dfa - put a dfa refcount
173 * @dfa: dfa to put refcount (MAYBE NULL)
174 *
175 * Requires: if @dfa != NULL that a valid refcount be held
176 */
177static inline void aa_put_dfa(struct aa_dfa *dfa)
178{
179 if (dfa)
180 kref_put(&dfa->count, aa_dfa_free_kref);
181}
182
183#define MATCH_FLAG_DIFF_ENCODE 0x80000000
184#define MARK_DIFF_ENCODE 0x40000000
185
186#endif /* __AA_MATCH_H */