projects/linux·blob master · refs

195 lines · 5.6 KiB

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#define YYTH_FLAG_OOB_TRANS 2
41#define YYTH_FLAGS (YYTH_FLAG_DIFF_ENCODE | YYTH_FLAG_OOB_TRANS)
42
43#define MAX_OOB_SUPPORTED 1
44
45struct table_set_header {
46 u32 th_magic; /* YYTH_MAGIC */
47 u32 th_hsize;
48 u32 th_ssize;
49 u16 th_flags;
50 char th_version[];
51};
52
53/* The YYTD_ID are one less than flex table mappings. The flex id
54 * has 1 subtracted at table load time, this allows us to directly use the
55 * ID's as indexes.
56 */
57#define YYTD_ID_ACCEPT 0
58#define YYTD_ID_BASE 1
59#define YYTD_ID_CHK 2
60#define YYTD_ID_DEF 3
61#define YYTD_ID_EC 4
62#define YYTD_ID_META 5
63#define YYTD_ID_ACCEPT2 6
64#define YYTD_ID_NXT 7
65#define YYTD_ID_TSIZE 8
66#define YYTD_ID_MAX 8
67
68#define YYTD_DATA8 1
69#define YYTD_DATA16 2
70#define YYTD_DATA32 4
71#define YYTD_DATA64 8
72
73/* ACCEPT & ACCEPT2 tables gets 6 dedicated flags, YYTD_DATAX define the
74 * first flags
75 */
76#define ACCEPT1_FLAGS(X) ((X) & 0x3f)
77#define ACCEPT2_FLAGS(X) ACCEPT1_FLAGS((X) >> YYTD_ID_ACCEPT2)
78#define TO_ACCEPT1_FLAG(X) ACCEPT1_FLAGS(X)
79#define TO_ACCEPT2_FLAG(X) (ACCEPT1_FLAGS(X) << YYTD_ID_ACCEPT2)
80#define DFA_FLAG_VERIFY_STATES 0x1000
81
82struct table_header {
83 u16 td_id;
84 u16 td_flags;
85 u32 td_hilen;
86 u32 td_lolen;
87 char td_data[];
88};
89
90#define TABLE_DATAU16(TABLE) ((u16 *)((TABLE)->td_data))
91#define TABLE_DATAU32(TABLE) ((u32 *)((TABLE)->td_data))
92#define DEFAULT_TABLE(DFA) ((u32 *)((DFA)->tables[YYTD_ID_DEF]->td_data))
93#define BASE_TABLE(DFA) ((u32 *)((DFA)->tables[YYTD_ID_BASE]->td_data))
94#define NEXT_TABLE(DFA) ((u32 *)((DFA)->tables[YYTD_ID_NXT]->td_data))
95#define CHECK_TABLE(DFA) ((u32 *)((DFA)->tables[YYTD_ID_CHK]->td_data))
96#define EQUIV_TABLE(DFA) ((u8 *)((DFA)->tables[YYTD_ID_EC]->td_data))
97#define ACCEPT_TABLE(DFA) ((u32 *)((DFA)->tables[YYTD_ID_ACCEPT]->td_data))
98#define ACCEPT_TABLE2(DFA) ((u32 *)((DFA)->tables[YYTD_ID_ACCEPT2]->td_data))
99
100struct aa_dfa {
101 struct kref count;
102 u16 flags;
103 u32 max_oob;
104 struct table_header *tables[YYTD_ID_TSIZE];
105};
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 BUILD_BUG_ON(sizeof(TTYPE) != sizeof(BTYPE)); \
113 if (IS_ENABLED(CONFIG_CPU_BIG_ENDIAN)) \
114 memcpy(__t, __b, (LEN) * sizeof(BTYPE)); \
115 else /* copy & convert from big-endian */ \
116 for (__i = 0; __i < LEN; __i++) { \
117 __t[__i] = NTOHX(&__b[__i]); \
118 } \
119 } while (0)
120
121static inline size_t table_size(size_t len, size_t el_size)
122{
123 return ALIGN(sizeof(struct table_header) + len * el_size, 8);
124}
125
126#define aa_state_t unsigned int
127
128struct aa_dfa *aa_dfa_unpack(const void *blob, size_t size, int flags);
129aa_state_t aa_dfa_match_len(const struct aa_dfa *dfa, aa_state_t start,
130 const char *str, int len);
131aa_state_t aa_dfa_match(const struct aa_dfa *dfa, aa_state_t start,
132 const char *str);
133aa_state_t aa_dfa_next(const struct aa_dfa *dfa, aa_state_t state,
134 const char c);
135aa_state_t aa_dfa_outofband_transition(const struct aa_dfa *dfa,
136 aa_state_t state);
137aa_state_t aa_dfa_match_until(const struct aa_dfa *dfa, aa_state_t start,
138 const char *str, const char **retpos);
139aa_state_t aa_dfa_matchn_until(const struct aa_dfa *dfa, aa_state_t start,
140 const char *str, int n, const char **retpos);
141
142void aa_dfa_free_kref(struct kref *kref);
143
144/* This needs to be a power of 2 */
145#define WB_HISTORY_SIZE 32
146struct match_workbuf {
147 unsigned int pos;
148 unsigned int len;
149 aa_state_t history[WB_HISTORY_SIZE];
150};
151#define DEFINE_MATCH_WB(N) \
152struct match_workbuf N = { \
153 .pos = 0, \
154 .len = 0, \
155}
156
157aa_state_t aa_dfa_leftmatch(const struct aa_dfa *dfa, aa_state_t start,
158 const char *str, unsigned int *count);
159
160/**
161 * aa_get_dfa - increment refcount on dfa @p
162 * @dfa: dfa (MAYBE NULL)
163 *
164 * Returns: pointer to @dfa if @dfa is NULL will return NULL
165 * Requires: @dfa must be held with valid refcount when called
166 */
167static inline struct aa_dfa *aa_get_dfa(struct aa_dfa *dfa)
168{
169 if (dfa)
170 kref_get(&(dfa->count));
171
172 return dfa;
173}
174
175/**
176 * aa_put_dfa - put a dfa refcount
177 * @dfa: dfa to put refcount (MAYBE NULL)
178 *
179 * Requires: if @dfa != NULL that a valid refcount be held
180 */
181static inline void aa_put_dfa(struct aa_dfa *dfa)
182{
183 if (dfa)
184 kref_put(&dfa->count, aa_dfa_free_kref);
185}
186
187#define MATCH_FLAG_DIFF_ENCODE 0x80000000
188#define MARK_DIFF_ENCODE 0x40000000
189#define MATCH_FLAG_OOB_TRANSITION 0x20000000
190#define MARK_DIFF_ENCODE_VERIFIED 0x10000000
191#define MATCH_FLAGS_MASK 0xff000000
192#define MATCH_FLAGS_VALID (MATCH_FLAG_DIFF_ENCODE | MATCH_FLAG_OOB_TRANSITION)
193#define MATCH_FLAGS_INVALID (MATCH_FLAGS_MASK & ~MATCH_FLAGS_VALID)
194
195#endif /* __AA_MATCH_H */