summaryrefslogtreecommitdiffstats
path: root/security/selinux/ss/hashtab.h
blob: 5f74dcc1360fef913067d99d6afad4d1d9547a5c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
/* SPDX-License-Identifier: GPL-2.0 */
/*
 * A hash table (hashtab) maintains associations between
 * key values and datum values.  The type of the key values
 * and the type of the datum values is arbitrary.  The
 * functions for hash computation and key comparison are
 * provided by the creator of the table.
 *
 * Author : Stephen Smalley, <stephen.smalley.work@gmail.com>
 */

#ifndef _SS_HASHTAB_H_
#define _SS_HASHTAB_H_

#include <linux/types.h>
#include <linux/errno.h>
#include <linux/sched.h>

#define HASHTAB_MAX_NODES U32_MAX

struct hashtab_key_params {
	u32 (*hash)(const void *key); /* hash func */
	int (*cmp)(const void *key1, const void *key2); /* comparison func */
};

struct hashtab_node {
	void *key;
	void *datum;
	struct hashtab_node *next;
};

struct hashtab {
	struct hashtab_node **htable; /* hash table */
	u32 size; /* number of slots in hash table */
	u32 nel; /* number of elements in hash table */
};

struct hashtab_info {
	u32 slots_used;
	u32 max_chain_len;
	u64 chain2_len_sum;
};

/*
 * Initializes a new hash table with the specified characteristics.
 *
 * Returns -ENOMEM if insufficient space is available or 0 otherwise.
 */
int hashtab_init(struct hashtab *h, u32 nel_hint);

int __hashtab_insert(struct hashtab *h, struct hashtab_node **dst, void *key,
		     void *datum);

/*
 * Inserts the specified (key, datum) pair into the specified hash table.
 *
 * Returns -ENOMEM on memory allocation error,
 * -EEXIST if there is already an entry with the same key,
 * -EINVAL for general errors or
  0 otherwise.
 */
static inline int hashtab_insert(struct hashtab *h, void *key, void *datum,
				 struct hashtab_key_params key_params)
{
	u32 hvalue;
	struct hashtab_node *prev, *cur;

	cond_resched();

	if (!h->size || h->nel == HASHTAB_MAX_NODES)
		return -EINVAL;

	hvalue = key_params.hash(key) & (h->size - 1);
	prev = NULL;
	cur = h->htable[hvalue];
	while (cur) {
		int cmp = key_params.cmp(key, cur->key);

		if (cmp == 0)
			return -EEXIST;
		if (cmp < 0)
			break;
		prev = cur;
		cur = cur->next;
	}

	return __hashtab_insert(h, prev ? &prev->next : &h->htable[hvalue], key,
				datum);
}

/*
 * Searches for the entry with the specified key in the hash table.
 *
 * Returns NULL if no entry has the specified key or
 * the datum of the entry otherwise.
 */
static inline void *hashtab_search(struct hashtab *h, const void *key,
				   struct hashtab_key_params key_params)
{
	u32 hvalue;
	struct hashtab_node *cur;

	if (!h->size)
		return NULL;

	hvalue = key_params.hash(key) & (h->size - 1);
	cur = h->htable[hvalue];
	while (cur) {
		int cmp = key_params.cmp(key, cur->key);

		if (cmp == 0)
			return cur->datum;
		if (cmp < 0)
			break;
		cur = cur->next;
	}
	return NULL;
}

/*
 * Destroys the specified hash table.
 */
void hashtab_destroy(struct hashtab *h);

/*
 * Applies the specified apply function to (key,datum,args)
 * for each entry in the specified hash table.
 *
 * The order in which the function is applied to the entries
 * is dependent upon the internal structure of the hash table.
 *
 * If apply returns a non-zero status, then hashtab_map will cease
 * iterating through the hash table and will propagate the error
 * return to its caller.
 */
int hashtab_map(struct hashtab *h, int (*apply)(void *k, void *d, void *args),
		void *args);

int hashtab_duplicate(struct hashtab *new, struct hashtab *orig,
		      int (*copy)(struct hashtab_node *new,
				  struct hashtab_node *orig, void *args),
		      int (*destroy)(void *k, void *d, void *args), void *args);

#ifdef CONFIG_SECURITY_SELINUX_DEBUG
/* Fill info with some hash table statistics */
void hashtab_stat(struct hashtab *h, struct hashtab_info *info);
#else
static inline void hashtab_stat(struct hashtab *h, struct hashtab_info *info)
{
	return;
}
#endif

#endif /* _SS_HASHTAB_H */