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 41 struct 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 78 struct 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 94 struct aa_dfa { 95 struct kref count; 96 u16 flags; 97 struct table_header *tables[YYTD_ID_TSIZE]; 98 }; 99 100 extern struct aa_dfa *nulldfa; 101 extern 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) 114 115 static 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 } 119 120 int aa_setup_dfa_engine(void); 121 void aa_teardown_dfa_engine(void); 122 123 struct aa_dfa *aa_dfa_unpack(void *blob, size_t size, int flags); 124 unsigned int aa_dfa_match_len(struct aa_dfa *dfa, unsigned int start, 125 const char *str, int len); 126 unsigned int aa_dfa_match(struct aa_dfa *dfa, unsigned int start, 127 const char *str); 128 unsigned int aa_dfa_next(struct aa_dfa *dfa, unsigned int state, 129 const char c); 130 unsigned int aa_dfa_match_until(struct aa_dfa *dfa, unsigned int start, 131 const char *str, const char **retpos); 132 unsigned int aa_dfa_matchn_until(struct aa_dfa *dfa, unsigned int start, 133 const char *str, int n, const char **retpos); 134 135 void aa_dfa_free_kref(struct kref *kref); 136 137 #define WB_HISTORY_SIZE 8 138 struct 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) \ 146 struct match_workbuf N = { \ 147 .count = 0, \ 148 .pos = 0, \ 149 .len = 0, \ 150 .size = WB_HISTORY_SIZE, \ 151 } 152 153 unsigned 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 */ 163 static 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 */ 177 static 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 */ 187