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 17 #include "context.h" 18 19 struct sidtab_entry_leaf { 20 struct context context; 21 }; 22 23 struct sidtab_node_inner; 24 struct sidtab_node_leaf; 25 26 union sidtab_entry_inner { 27 struct sidtab_node_inner *ptr_inner; 28 struct sidtab_node_leaf *ptr_leaf; 29 }; 30 31 /* align node size to page boundary */ 32 #define SIDTAB_NODE_ALLOC_SHIFT PAGE_SHIFT 33 #define SIDTAB_NODE_ALLOC_SIZE PAGE_SIZE 34 35 #define size_to_shift(size) ((size) == 1 ? 1 : (const_ilog2((size) - 1) + 1)) 36 37 #define SIDTAB_INNER_SHIFT \ 38 (SIDTAB_NODE_ALLOC_SHIFT - size_to_shift(sizeof(union sidtab_entry_inner))) 39 #define SIDTAB_INNER_ENTRIES ((size_t)1 << SIDTAB_INNER_SHIFT) 40 #define SIDTAB_LEAF_ENTRIES \ 41 (SIDTAB_NODE_ALLOC_SIZE / sizeof(struct sidtab_entry_leaf)) 42 43 #define SIDTAB_MAX_BITS 32 44 #define SIDTAB_MAX U32_MAX 45 /* ensure enough tree levels for SIDTAB_MAX entries */ 46 #define SIDTAB_MAX_LEVEL \ 47 DIV_ROUND_UP(SIDTAB_MAX_BITS - size_to_shift(SIDTAB_LEAF_ENTRIES), \ 48 SIDTAB_INNER_SHIFT) 49 50 struct sidtab_node_leaf { 51 struct sidtab_entry_leaf entries[SIDTAB_LEAF_ENTRIES]; 52 }; 53 54 struct sidtab_node_inner { 55 union sidtab_entry_inner entries[SIDTAB_INNER_ENTRIES]; 56 }; 57 58 struct sidtab_isid_entry { 59 int set; 60 struct context context; 61 }; 62 63 struct sidtab_convert_params { 64 int (*func)(struct context *oldc, struct context *newc, void *args); 65 void *args; 66 struct sidtab *target; 67 }; 68 69 #define SIDTAB_RCACHE_SIZE 3 70 71 struct sidtab { 72 /* 73 * lock-free read access only for as many items as a prior read of 74 * 'count' 75 */ 76 union sidtab_entry_inner roots[SIDTAB_MAX_LEVEL + 1]; 77 /* 78 * access atomically via {READ|WRITE}_ONCE(); only increment under 79 * spinlock 80 */ 81 u32 count; 82 /* access only under spinlock */ 83 struct sidtab_convert_params *convert; 84 spinlock_t lock; 85 86 /* reverse lookup cache - access atomically via {READ|WRITE}_ONCE() */ 87 u32 rcache[SIDTAB_RCACHE_SIZE]; 88 89 /* index == SID - 1 (no entry for SECSID_NULL) */ 90 struct sidtab_isid_entry isids[SECINITSID_NUM]; 91 }; 92 93 int sidtab_init(struct sidtab *s); 94 int sidtab_set_initial(struct sidtab *s, u32 sid, struct context *context); 95 struct context *sidtab_search(struct sidtab *s, u32 sid); 96 struct context *sidtab_search_force(struct sidtab *s, u32 sid); 97 98 int sidtab_convert(struct sidtab *s, struct sidtab_convert_params *params); 99 100 int sidtab_context_to_sid(struct sidtab *s, struct context *context, u32 *sid); 101 102 void sidtab_destroy(struct sidtab *s); 103 104 #endif /* _SS_SIDTAB_H_ */ 105 106 107