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