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, gfp_t gfp_flags);
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
sidtab_search(struct sidtab * s,u32 sid)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
sidtab_search_force(struct sidtab * s,u32 sid)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
sidtab_sid2str_put(struct sidtab * s,struct sidtab_entry * entry,const char * str,u32 str_len)144 static inline void sidtab_sid2str_put(struct sidtab *s,
145 struct sidtab_entry *entry,
146 const char *str, u32 str_len)
147 {
148 }
sidtab_sid2str_get(struct sidtab * s,struct sidtab_entry * entry,char ** out,u32 * out_len)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
