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_leaf { 21 u32 sid; 22 struct context context; 23 struct hlist_node list; 24 }; 25 26 struct sidtab_node_inner; 27 struct sidtab_node_leaf; 28 29 union sidtab_entry_inner { 30 struct sidtab_node_inner *ptr_inner; 31 struct sidtab_node_leaf *ptr_leaf; 32 }; 33 34 /* align node size to page boundary */ 35 #define SIDTAB_NODE_ALLOC_SHIFT PAGE_SHIFT 36 #define SIDTAB_NODE_ALLOC_SIZE PAGE_SIZE 37 38 #define size_to_shift(size) ((size) == 1 ? 1 : (const_ilog2((size) - 1) + 1)) 39 40 #define SIDTAB_INNER_SHIFT \ 41 (SIDTAB_NODE_ALLOC_SHIFT - size_to_shift(sizeof(union sidtab_entry_inner))) 42 #define SIDTAB_INNER_ENTRIES ((size_t)1 << SIDTAB_INNER_SHIFT) 43 #define SIDTAB_LEAF_ENTRIES \ 44 (SIDTAB_NODE_ALLOC_SIZE / sizeof(struct sidtab_entry_leaf)) 45 46 #define SIDTAB_MAX_BITS 32 47 #define SIDTAB_MAX U32_MAX 48 /* ensure enough tree levels for SIDTAB_MAX entries */ 49 #define SIDTAB_MAX_LEVEL \ 50 DIV_ROUND_UP(SIDTAB_MAX_BITS - size_to_shift(SIDTAB_LEAF_ENTRIES), \ 51 SIDTAB_INNER_SHIFT) 52 53 struct sidtab_node_leaf { 54 struct sidtab_entry_leaf entries[SIDTAB_LEAF_ENTRIES]; 55 }; 56 57 struct sidtab_node_inner { 58 union sidtab_entry_inner entries[SIDTAB_INNER_ENTRIES]; 59 }; 60 61 struct sidtab_isid_entry { 62 int set; 63 struct sidtab_entry_leaf leaf; 64 }; 65 66 struct sidtab_convert_params { 67 int (*func)(struct context *oldc, struct context *newc, void *args); 68 void *args; 69 struct sidtab *target; 70 }; 71 72 #define SIDTAB_HASH_BITS CONFIG_SECURITY_SELINUX_SIDTAB_HASH_BITS 73 #define SIDTAB_HASH_BUCKETS (1 << SIDTAB_HASH_BITS) 74 75 struct sidtab { 76 /* 77 * lock-free read access only for as many items as a prior read of 78 * 'count' 79 */ 80 union sidtab_entry_inner roots[SIDTAB_MAX_LEVEL + 1]; 81 /* 82 * access atomically via {READ|WRITE}_ONCE(); only increment under 83 * spinlock 84 */ 85 u32 count; 86 /* access only under spinlock */ 87 struct sidtab_convert_params *convert; 88 spinlock_t lock; 89 90 /* index == SID - 1 (no entry for SECSID_NULL) */ 91 struct sidtab_isid_entry isids[SECINITSID_NUM]; 92 93 /* Hash table for fast reverse context-to-sid lookups. */ 94 DECLARE_HASHTABLE(context_to_sid, SIDTAB_HASH_BITS); 95 }; 96 97 int sidtab_init(struct sidtab *s); 98 int sidtab_set_initial(struct sidtab *s, u32 sid, struct context *context); 99 struct context *sidtab_search(struct sidtab *s, u32 sid); 100 struct context *sidtab_search_force(struct sidtab *s, u32 sid); 101 102 int sidtab_convert(struct sidtab *s, struct sidtab_convert_params *params); 103 104 int sidtab_context_to_sid(struct sidtab *s, struct context *context, u32 *sid); 105 106 void sidtab_destroy(struct sidtab *s); 107 108 int sidtab_hash_stats(struct sidtab *sidtab, char *page); 109 110 #endif /* _SS_SIDTAB_H_ */ 111 112 113