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
20struct 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
30union 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
54struct sidtab_node_leaf {
55	struct sidtab_entry entries[SIDTAB_LEAF_ENTRIES];
56};
57
58struct sidtab_node_inner {
59	union sidtab_entry_inner entries[SIDTAB_INNER_ENTRIES];
60};
61
62struct sidtab_isid_entry {
63	int set;
64	struct sidtab_entry entry;
65};
66
67struct 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
76struct 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
106int sidtab_init(struct sidtab *s);
107int sidtab_set_initial(struct sidtab *s, u32 sid, struct context *context);
108struct sidtab_entry *sidtab_search_entry(struct sidtab *s, u32 sid);
109struct sidtab_entry *sidtab_search_entry_force(struct sidtab *s, u32 sid);
110
111static 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
118static 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
125int sidtab_convert(struct sidtab *s, struct sidtab_convert_params *params);
126
127void sidtab_cancel_convert(struct sidtab *s);
128
129void sidtab_freeze_begin(struct sidtab *s, unsigned long *flags) __acquires(&s->lock);
130void sidtab_freeze_end(struct sidtab *s, unsigned long *flags) __releases(&s->lock);
131
132int sidtab_context_to_sid(struct sidtab *s, struct context *context, u32 *sid);
133
134void sidtab_destroy(struct sidtab *s);
135
136int sidtab_hash_stats(struct sidtab *sidtab, char *page);
137
138#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0
139void sidtab_sid2str_put(struct sidtab *s, struct sidtab_entry *entry,
140			const char *str, u32 str_len);
141int sidtab_sid2str_get(struct sidtab *s, struct sidtab_entry *entry,
142		       char **out, u32 *out_len);
143#else
144static inline void sidtab_sid2str_put(struct sidtab *s,
145				      struct sidtab_entry *entry,
146				      const char *str, u32 str_len)
147{
148}
149static 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