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, <stephen.smalley.work@gmail.com>
7 * Author: Ondrej Mosnacek, <omosnacek@gmail.com>
8 *
9 * Copyright (C) 2018 Red Hat, Inc.
10 */
11
12#ifndef _SS_SIDTAB_H_
13#define _SS_SIDTAB_H_
14
15#include <linux/spinlock_types.h>
16#include <linux/log2.h>
17#include <linux/hashtable.h>
18
19#include "context.h"
20
21struct sidtab_entry {
22 u32 sid;
23 u32 hash;
24 struct context context;
25#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0
26 struct sidtab_str_cache __rcu *cache;
27#endif
28 struct hlist_node list;
29};
30
31union sidtab_entry_inner {
32 struct sidtab_node_inner *ptr_inner;
33 struct sidtab_node_leaf *ptr_leaf;
34};
35
36/* align node size to page boundary */
37#define SIDTAB_NODE_ALLOC_SHIFT PAGE_SHIFT
38#define SIDTAB_NODE_ALLOC_SIZE PAGE_SIZE
39
40#define size_to_shift(size) ((size) == 1 ? 1 : (const_ilog2((size)-1) + 1))
41
42#define SIDTAB_INNER_SHIFT \
43 (SIDTAB_NODE_ALLOC_SHIFT - \
44 size_to_shift(sizeof(union sidtab_entry_inner)))
45#define SIDTAB_INNER_ENTRIES ((size_t)1 << SIDTAB_INNER_SHIFT)
46#define SIDTAB_LEAF_ENTRIES \
47 (SIDTAB_NODE_ALLOC_SIZE / sizeof(struct sidtab_entry))
48
49#define SIDTAB_MAX_BITS 32
50#define SIDTAB_MAX U32_MAX
51/* ensure enough tree levels for SIDTAB_MAX entries */
52#define SIDTAB_MAX_LEVEL \
53 DIV_ROUND_UP(SIDTAB_MAX_BITS - size_to_shift(SIDTAB_LEAF_ENTRIES), \
54 SIDTAB_INNER_SHIFT)
55
56struct sidtab_node_leaf {
57 struct sidtab_entry entries[SIDTAB_LEAF_ENTRIES];
58};
59
60struct sidtab_node_inner {
61 union sidtab_entry_inner entries[SIDTAB_INNER_ENTRIES];
62};
63
64struct sidtab_isid_entry {
65 int set;
66 struct sidtab_entry entry;
67};
68
69struct sidtab_convert_params {
70 struct convert_context_args *args;
71 struct sidtab *target;
72};
73
74#define SIDTAB_HASH_BITS CONFIG_SECURITY_SELINUX_SIDTAB_HASH_BITS
75#define SIDTAB_HASH_BUCKETS (1 << SIDTAB_HASH_BITS)
76
77struct sidtab {
78 /*
79 * lock-free read access only for as many items as a prior read of
80 * 'count'
81 */
82 union sidtab_entry_inner roots[SIDTAB_MAX_LEVEL + 1];
83 /*
84 * access atomically via {READ|WRITE}_ONCE(); only increment under
85 * spinlock
86 */
87 u32 count;
88 /* access only under spinlock */
89 struct sidtab_convert_params *convert;
90 bool frozen;
91 spinlock_t lock;
92
93#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0
94 /* SID -> context string cache */
95 u32 cache_free_slots;
96 struct list_head cache_lru_list;
97 spinlock_t cache_lock;
98#endif
99
100 /* index == SID - 1 (no entry for SECSID_NULL) */
101 struct sidtab_isid_entry isids[SECINITSID_NUM];
102
103 /* Hash table for fast reverse context-to-sid lookups. */
104 DECLARE_HASHTABLE(context_to_sid, SIDTAB_HASH_BITS);
105};
106
107int sidtab_init(struct sidtab *s);
108int sidtab_set_initial(struct sidtab *s, u32 sid, struct context *context);
109struct sidtab_entry *sidtab_search_entry(struct sidtab *s, u32 sid);
110struct sidtab_entry *sidtab_search_entry_force(struct sidtab *s, u32 sid);
111
112static inline struct context *sidtab_search(struct sidtab *s, u32 sid)
113{
114 struct sidtab_entry *entry = sidtab_search_entry(s, sid);
115
116 return entry ? &entry->context : NULL;
117}
118
119static inline struct context *sidtab_search_force(struct sidtab *s, u32 sid)
120{
121 struct sidtab_entry *entry = sidtab_search_entry_force(s, sid);
122
123 return entry ? &entry->context : NULL;
124}
125
126int sidtab_convert(struct sidtab *s, struct sidtab_convert_params *params);
127
128void sidtab_cancel_convert(struct sidtab *s);
129
130void sidtab_freeze_begin(struct sidtab *s, unsigned long *flags)
131 __acquires(&s->lock);
132void sidtab_freeze_end(struct sidtab *s, unsigned long *flags)
133 __releases(&s->lock);
134
135int sidtab_context_to_sid(struct sidtab *s, struct context *context, u32 *sid);
136
137void sidtab_destroy(struct sidtab *s);
138
139int sidtab_hash_stats(struct sidtab *sidtab, char *page);
140
141#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0
142void sidtab_sid2str_put(struct sidtab *s, struct sidtab_entry *entry,
143 const char *str, u32 str_len);
144int sidtab_sid2str_get(struct sidtab *s, struct sidtab_entry *entry, char **out,
145 u32 *out_len);
146#else
147static inline void sidtab_sid2str_put(struct sidtab *s,
148 struct sidtab_entry *entry,
149 const char *str, u32 str_len)
150{
151}
152static inline int sidtab_sid2str_get(struct sidtab *s,
153 struct sidtab_entry *entry, char **out,
154 u32 *out_len)
155{
156 return -ENOENT;
157}
158#endif /* CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0 */
159
160#endif /* _SS_SIDTAB_H_ */
161