1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* 3 * A security identifier table (sidtab) is a lookup table 4 * of security context structures indexed by SID value. 5 * 6 * Original author: Stephen Smalley, <sds@tycho.nsa.gov> 7 * Author: Ondrej Mosnacek, <omosnacek@gmail.com> 8 * 9 * Copyright (C) 2018 Red Hat, Inc. 10 */ 11 #ifndef _SS_SIDTAB_H_ 12 #define _SS_SIDTAB_H_ 13 14 #include <linux/spinlock_types.h> 15 #include <linux/log2.h> 16 #include <linux/hashtable.h> 17 18 #include "context.h" 19 20 struct sidtab_entry { 21 u32 sid; 22 u32 hash; 23 struct context context; 24 #if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0 25 struct sidtab_str_cache __rcu *cache; 26 #endif 27 struct hlist_node list; 28 }; 29 30 union sidtab_entry_inner { 31 struct sidtab_node_inner *ptr_inner; 32 struct sidtab_node_leaf *ptr_leaf; 33 }; 34 35 /* align node size to page boundary */ 36 #define SIDTAB_NODE_ALLOC_SHIFT PAGE_SHIFT 37 #define SIDTAB_NODE_ALLOC_SIZE PAGE_SIZE 38 39 #define size_to_shift(size) ((size) == 1 ? 1 : (const_ilog2((size) - 1) + 1)) 40 41 #define SIDTAB_INNER_SHIFT \ 42 (SIDTAB_NODE_ALLOC_SHIFT - size_to_shift(sizeof(union sidtab_entry_inner))) 43 #define SIDTAB_INNER_ENTRIES ((size_t)1 << SIDTAB_INNER_SHIFT) 44 #define SIDTAB_LEAF_ENTRIES \ 45 (SIDTAB_NODE_ALLOC_SIZE / sizeof(struct sidtab_entry)) 46 47 #define SIDTAB_MAX_BITS 32 48 #define SIDTAB_MAX U32_MAX 49 /* ensure enough tree levels for SIDTAB_MAX entries */ 50 #define SIDTAB_MAX_LEVEL \ 51 DIV_ROUND_UP(SIDTAB_MAX_BITS - size_to_shift(SIDTAB_LEAF_ENTRIES), \ 52 SIDTAB_INNER_SHIFT) 53 54 struct sidtab_node_leaf { 55 struct sidtab_entry entries[SIDTAB_LEAF_ENTRIES]; 56 }; 57 58 struct sidtab_node_inner { 59 union sidtab_entry_inner entries[SIDTAB_INNER_ENTRIES]; 60 }; 61 62 struct sidtab_isid_entry { 63 int set; 64 struct sidtab_entry entry; 65 }; 66 67 struct sidtab_convert_params { 68 int (*func)(struct context *oldc, struct context *newc, void *args); 69 void *args; 70 struct sidtab *target; 71 }; 72 73 #define SIDTAB_HASH_BITS CONFIG_SECURITY_SELINUX_SIDTAB_HASH_BITS 74 #define SIDTAB_HASH_BUCKETS (1 << SIDTAB_HASH_BITS) 75 76 struct sidtab { 77 /* 78 * lock-free read access only for as many items as a prior read of 79 * 'count' 80 */ 81 union sidtab_entry_inner roots[SIDTAB_MAX_LEVEL + 1]; 82 /* 83 * access atomically via {READ|WRITE}_ONCE(); only increment under 84 * spinlock 85 */ 86 u32 count; 87 /* access only under spinlock */ 88 struct sidtab_convert_params *convert; 89 bool frozen; 90 spinlock_t lock; 91 92 #if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0 93 /* SID -> context string cache */ 94 u32 cache_free_slots; 95 struct list_head cache_lru_list; 96 spinlock_t cache_lock; 97 #endif 98 99 /* index == SID - 1 (no entry for SECSID_NULL) */ 100 struct sidtab_isid_entry isids[SECINITSID_NUM]; 101 102 /* Hash table for fast reverse context-to-sid lookups. */ 103 DECLARE_HASHTABLE(context_to_sid, SIDTAB_HASH_BITS); 104 }; 105 106 int sidtab_init(struct sidtab *s); 107 int sidtab_set_initial(struct sidtab *s, u32 sid, struct context *context); 108 struct sidtab_entry *sidtab_search_entry(struct sidtab *s, u32 sid); 109 struct sidtab_entry *sidtab_search_entry_force(struct sidtab *s, u32 sid); 110 111 static inline struct context *sidtab_search(struct sidtab *s, u32 sid) 112 { 113 struct sidtab_entry *entry = sidtab_search_entry(s, sid); 114 115 return entry ? &entry->context : NULL; 116 } 117 118 static inline struct context *sidtab_search_force(struct sidtab *s, u32 sid) 119 { 120 struct sidtab_entry *entry = sidtab_search_entry_force(s, sid); 121 122 return entry ? &entry->context : NULL; 123 } 124 125 int sidtab_convert(struct sidtab *s, struct sidtab_convert_params *params); 126 127 void sidtab_cancel_convert(struct sidtab *s); 128 129 void sidtab_freeze_begin(struct sidtab *s, unsigned long *flags) __acquires(&s->lock); 130 void sidtab_freeze_end(struct sidtab *s, unsigned long *flags) __releases(&s->lock); 131 132 int sidtab_context_to_sid(struct sidtab *s, struct context *context, u32 *sid); 133 134 void sidtab_destroy(struct sidtab *s); 135 136 int sidtab_hash_stats(struct sidtab *sidtab, char *page); 137 138 #if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0 139 void sidtab_sid2str_put(struct sidtab *s, struct sidtab_entry *entry, 140 const char *str, u32 str_len); 141 int sidtab_sid2str_get(struct sidtab *s, struct sidtab_entry *entry, 142 char **out, u32 *out_len); 143 #else 144 static inline void sidtab_sid2str_put(struct sidtab *s, 145 struct sidtab_entry *entry, 146 const char *str, u32 str_len) 147 { 148 } 149 static inline int sidtab_sid2str_get(struct sidtab *s, 150 struct sidtab_entry *entry, 151 char **out, u32 *out_len) 152 { 153 return -ENOENT; 154 } 155 #endif /* CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0 */ 156 157 #endif /* _SS_SIDTAB_H_ */ 158 159 160