1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * A hash table (hashtab) maintains associations between
4 * key values and datum values. The type of the key values
5 * and the type of the datum values is arbitrary. The
6 * functions for hash computation and key comparison are
7 * provided by the creator of the table.
8 *
9 * Author : Stephen Smalley, <stephen.smalley.work@gmail.com>
10 */
11
12#ifndef _SS_HASHTAB_H_
13#define _SS_HASHTAB_H_
14
15#include <linux/types.h>
16#include <linux/errno.h>
17#include <linux/sched.h>
18
19#define HASHTAB_MAX_NODES U32_MAX
20
21struct hashtab_key_params {
22 u32 (*hash)(const void *key); /* hash func */
23 int (*cmp)(const void *key1, const void *key2); /* comparison func */
24};
25
26struct hashtab_node {
27 void *key;
28 void *datum;
29 struct hashtab_node *next;
30};
31
32struct hashtab {
33 struct hashtab_node **htable; /* hash table */
34 u32 size; /* number of slots in hash table */
35 u32 nel; /* number of elements in hash table */
36};
37
38struct hashtab_info {
39 u32 slots_used;
40 u32 max_chain_len;
41 u64 chain2_len_sum;
42};
43
44/*
45 * Initializes a new hash table with the specified characteristics.
46 *
47 * Returns -ENOMEM if insufficient space is available or 0 otherwise.
48 */
49int hashtab_init(struct hashtab *h, u32 nel_hint);
50
51int __hashtab_insert(struct hashtab *h, struct hashtab_node **dst, void *key,
52 void *datum);
53
54/*
55 * Inserts the specified (key, datum) pair into the specified hash table.
56 *
57 * Returns -ENOMEM on memory allocation error,
58 * -EEXIST if there is already an entry with the same key,
59 * -EINVAL for general errors or
60 0 otherwise.
61 */
62static inline int hashtab_insert(struct hashtab *h, void *key, void *datum,
63 struct hashtab_key_params key_params)
64{
65 u32 hvalue;
66 struct hashtab_node *prev, *cur;
67
68 cond_resched();
69
70 if (!h->size || h->nel == HASHTAB_MAX_NODES)
71 return -EINVAL;
72
73 hvalue = key_params.hash(key) & (h->size - 1);
74 prev = NULL;
75 cur = h->htable[hvalue];
76 while (cur) {
77 int cmp = key_params.cmp(key, cur->key);
78
79 if (cmp == 0)
80 return -EEXIST;
81 if (cmp < 0)
82 break;
83 prev = cur;
84 cur = cur->next;
85 }
86
87 return __hashtab_insert(h, dst: prev ? &prev->next : &h->htable[hvalue], key,
88 datum);
89}
90
91/*
92 * Searches for the entry with the specified key in the hash table.
93 *
94 * Returns NULL if no entry has the specified key or
95 * the datum of the entry otherwise.
96 */
97static inline void *hashtab_search(struct hashtab *h, const void *key,
98 struct hashtab_key_params key_params)
99{
100 u32 hvalue;
101 struct hashtab_node *cur;
102
103 if (!h->size)
104 return NULL;
105
106 hvalue = key_params.hash(key) & (h->size - 1);
107 cur = h->htable[hvalue];
108 while (cur) {
109 int cmp = key_params.cmp(key, cur->key);
110
111 if (cmp == 0)
112 return cur->datum;
113 if (cmp < 0)
114 break;
115 cur = cur->next;
116 }
117 return NULL;
118}
119
120/*
121 * Destroys the specified hash table.
122 */
123void hashtab_destroy(struct hashtab *h);
124
125/*
126 * Applies the specified apply function to (key,datum,args)
127 * for each entry in the specified hash table.
128 *
129 * The order in which the function is applied to the entries
130 * is dependent upon the internal structure of the hash table.
131 *
132 * If apply returns a non-zero status, then hashtab_map will cease
133 * iterating through the hash table and will propagate the error
134 * return to its caller.
135 */
136int hashtab_map(struct hashtab *h, int (*apply)(void *k, void *d, void *args),
137 void *args);
138
139int hashtab_duplicate(struct hashtab *new, const struct hashtab *orig,
140 int (*copy)(struct hashtab_node *new,
141 const struct hashtab_node *orig, void *args),
142 int (*destroy)(void *k, void *d, void *args), void *args);
143
144#ifdef CONFIG_SECURITY_SELINUX_DEBUG
145/* Fill info with some hash table statistics */
146void hashtab_stat(struct hashtab *h, struct hashtab_info *info);
147#else
148static inline void hashtab_stat(struct hashtab *h, struct hashtab_info *info)
149{
150 return;
151}
152#endif
153
154#endif /* _SS_HASHTAB_H */
155