match.h

  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(void *blob, size_t size, int flags);
129aa_state_t aa_dfa_match_len(struct aa_dfa *dfa, aa_state_t start,
130			    const char *str, int len);
131aa_state_t aa_dfa_match(struct aa_dfa *dfa, aa_state_t start,
132			const char *str);
133aa_state_t aa_dfa_next(struct aa_dfa *dfa, aa_state_t state, const char c);
134aa_state_t aa_dfa_outofband_transition(struct aa_dfa *dfa, aa_state_t state);
135aa_state_t aa_dfa_match_until(struct aa_dfa *dfa, aa_state_t start,
136			      const char *str, const char **retpos);
137aa_state_t aa_dfa_matchn_until(struct aa_dfa *dfa, aa_state_t start,
138			       const char *str, int n, const char **retpos);
139
140void aa_dfa_free_kref(struct kref *kref);
141
142/* This needs to be a power of 2 */
143#define WB_HISTORY_SIZE 32
144struct match_workbuf {
145	unsigned int pos;
146	unsigned int len;
147	aa_state_t history[WB_HISTORY_SIZE];
148};
149#define DEFINE_MATCH_WB(N)		\
150struct match_workbuf N = {		\
151	.pos = 0,			\
152	.len = 0,			\
153}
154
155aa_state_t aa_dfa_leftmatch(struct aa_dfa *dfa, aa_state_t start,
156			    const char *str, unsigned int *count);
157
158/**
159 * aa_get_dfa - increment refcount on dfa @p
160 * @dfa: dfa  (MAYBE NULL)
161 *
162 * Returns: pointer to @dfa if @dfa is NULL will return NULL
163 * Requires: @dfa must be held with valid refcount when called
164 */
165static inline struct aa_dfa *aa_get_dfa(struct aa_dfa *dfa)
166{
167	if (dfa)
168		kref_get(&(dfa->count));
169
170	return dfa;
171}
172
173/**
174 * aa_put_dfa - put a dfa refcount
175 * @dfa: dfa to put refcount   (MAYBE NULL)
176 *
177 * Requires: if @dfa != NULL that a valid refcount be held
178 */
179static inline void aa_put_dfa(struct aa_dfa *dfa)
180{
181	if (dfa)
182		kref_put(&dfa->count, aa_dfa_free_kref);
183}
184
185#define MATCH_FLAG_DIFF_ENCODE 0x80000000
186#define MARK_DIFF_ENCODE 0x40000000
187#define MATCH_FLAG_OOB_TRANSITION 0x20000000
188#define MARK_DIFF_ENCODE_VERIFIED 0x10000000
189#define MATCH_FLAGS_MASK 0xff000000
190#define MATCH_FLAGS_VALID (MATCH_FLAG_DIFF_ENCODE | MATCH_FLAG_OOB_TRANSITION)
191#define MATCH_FLAGS_INVALID (MATCH_FLAGS_MASK & ~MATCH_FLAGS_VALID)
192
193#endif /* __AA_MATCH_H */