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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Implementation of the hash table type.
4 *
5 * Author : Stephen Smalley, <sds@tycho.nsa.gov>
6 */
7#include <linux/kernel.h>
8#include <linux/slab.h>
9#include <linux/errno.h>
10#include "hashtab.h"
11#include "security.h"
12
13static struct kmem_cache *hashtab_node_cachep __ro_after_init;
14
15/*
16 * Here we simply round the number of elements up to the nearest power of two.
17 * I tried also other options like rounding down or rounding to the closest
18 * power of two (up or down based on which is closer), but I was unable to
19 * find any significant difference in lookup/insert performance that would
20 * justify switching to a different (less intuitive) formula. It could be that
21 * a different formula is actually more optimal, but any future changes here
22 * should be supported with performance/memory usage data.
23 *
24 * The total memory used by the htable arrays (only) with Fedora policy loaded
25 * is approximately 163 KB at the time of writing.
26 */
27static u32 hashtab_compute_size(u32 nel)
28{
29 return nel == 0 ? 0 : roundup_pow_of_two(nel);
30}
31
32int hashtab_init(struct hashtab *h, u32 nel_hint)
33{
34 u32 size = hashtab_compute_size(nel_hint);
35
36 /* should already be zeroed, but better be safe */
37 h->nel = 0;
38 h->size = 0;
39 h->htable = NULL;
40
41 if (size) {
42 h->htable = kcalloc(size, sizeof(*h->htable), GFP_KERNEL);
43 if (!h->htable)
44 return -ENOMEM;
45 h->size = size;
46 }
47 return 0;
48}
49
50int __hashtab_insert(struct hashtab *h, struct hashtab_node **dst,
51 void *key, void *datum)
52{
53 struct hashtab_node *newnode;
54
55 newnode = kmem_cache_zalloc(hashtab_node_cachep, GFP_KERNEL);
56 if (!newnode)
57 return -ENOMEM;
58 newnode->key = key;
59 newnode->datum = datum;
60 newnode->next = *dst;
61 *dst = newnode;
62
63 h->nel++;
64 return 0;
65}
66
67void hashtab_destroy(struct hashtab *h)
68{
69 u32 i;
70 struct hashtab_node *cur, *temp;
71
72 for (i = 0; i < h->size; i++) {
73 cur = h->htable[i];
74 while (cur) {
75 temp = cur;
76 cur = cur->next;
77 kmem_cache_free(hashtab_node_cachep, temp);
78 }
79 h->htable[i] = NULL;
80 }
81
82 kfree(h->htable);
83 h->htable = NULL;
84}
85
86int hashtab_map(struct hashtab *h,
87 int (*apply)(void *k, void *d, void *args),
88 void *args)
89{
90 u32 i;
91 int ret;
92 struct hashtab_node *cur;
93
94 for (i = 0; i < h->size; i++) {
95 cur = h->htable[i];
96 while (cur) {
97 ret = apply(cur->key, cur->datum, args);
98 if (ret)
99 return ret;
100 cur = cur->next;
101 }
102 }
103 return 0;
104}
105
106
107void hashtab_stat(struct hashtab *h, struct hashtab_info *info)
108{
109 u32 i, chain_len, slots_used, max_chain_len;
110 struct hashtab_node *cur;
111
112 slots_used = 0;
113 max_chain_len = 0;
114 for (i = 0; i < h->size; i++) {
115 cur = h->htable[i];
116 if (cur) {
117 slots_used++;
118 chain_len = 0;
119 while (cur) {
120 chain_len++;
121 cur = cur->next;
122 }
123
124 if (chain_len > max_chain_len)
125 max_chain_len = chain_len;
126 }
127 }
128
129 info->slots_used = slots_used;
130 info->max_chain_len = max_chain_len;
131}
132
133int hashtab_duplicate(struct hashtab *new, struct hashtab *orig,
134 int (*copy)(struct hashtab_node *new,
135 struct hashtab_node *orig, void *args),
136 int (*destroy)(void *k, void *d, void *args),
137 void *args)
138{
139 struct hashtab_node *cur, *tmp, *tail;
140 int i, rc;
141
142 memset(new, 0, sizeof(*new));
143
144 new->htable = kcalloc(orig->size, sizeof(*new->htable), GFP_KERNEL);
145 if (!new->htable)
146 return -ENOMEM;
147
148 new->size = orig->size;
149
150 for (i = 0; i < orig->size; i++) {
151 tail = NULL;
152 for (cur = orig->htable[i]; cur; cur = cur->next) {
153 tmp = kmem_cache_zalloc(hashtab_node_cachep,
154 GFP_KERNEL);
155 if (!tmp)
156 goto error;
157 rc = copy(tmp, cur, args);
158 if (rc) {
159 kmem_cache_free(hashtab_node_cachep, tmp);
160 goto error;
161 }
162 tmp->next = NULL;
163 if (!tail)
164 new->htable[i] = tmp;
165 else
166 tail->next = tmp;
167 tail = tmp;
168 new->nel++;
169 }
170 }
171
172 return 0;
173
174 error:
175 for (i = 0; i < new->size; i++) {
176 for (cur = new->htable[i]; cur; cur = tmp) {
177 tmp = cur->next;
178 destroy(cur->key, cur->datum, args);
179 kmem_cache_free(hashtab_node_cachep, cur);
180 }
181 }
182 kfree(new->htable);
183 memset(new, 0, sizeof(*new));
184 return -ENOMEM;
185}
186
187void __init hashtab_cache_init(void)
188{
189 hashtab_node_cachep = kmem_cache_create("hashtab_node",
190 sizeof(struct hashtab_node),
191 0, SLAB_PANIC, NULL);
192}
1/*
2 * Implementation of the hash table type.
3 *
4 * Author : Stephen Smalley, <sds@epoch.ncsc.mil>
5 */
6#include <linux/kernel.h>
7#include <linux/slab.h>
8#include <linux/errno.h>
9#include "hashtab.h"
10
11struct hashtab *hashtab_create(u32 (*hash_value)(struct hashtab *h, const void *key),
12 int (*keycmp)(struct hashtab *h, const void *key1, const void *key2),
13 u32 size)
14{
15 struct hashtab *p;
16 u32 i;
17
18 p = kzalloc(sizeof(*p), GFP_KERNEL);
19 if (p == NULL)
20 return p;
21
22 p->size = size;
23 p->nel = 0;
24 p->hash_value = hash_value;
25 p->keycmp = keycmp;
26 p->htable = kmalloc(sizeof(*(p->htable)) * size, GFP_KERNEL);
27 if (p->htable == NULL) {
28 kfree(p);
29 return NULL;
30 }
31
32 for (i = 0; i < size; i++)
33 p->htable[i] = NULL;
34
35 return p;
36}
37
38int hashtab_insert(struct hashtab *h, void *key, void *datum)
39{
40 u32 hvalue;
41 struct hashtab_node *prev, *cur, *newnode;
42
43 if (!h || h->nel == HASHTAB_MAX_NODES)
44 return -EINVAL;
45
46 hvalue = h->hash_value(h, key);
47 prev = NULL;
48 cur = h->htable[hvalue];
49 while (cur && h->keycmp(h, key, cur->key) > 0) {
50 prev = cur;
51 cur = cur->next;
52 }
53
54 if (cur && (h->keycmp(h, key, cur->key) == 0))
55 return -EEXIST;
56
57 newnode = kzalloc(sizeof(*newnode), GFP_KERNEL);
58 if (newnode == NULL)
59 return -ENOMEM;
60 newnode->key = key;
61 newnode->datum = datum;
62 if (prev) {
63 newnode->next = prev->next;
64 prev->next = newnode;
65 } else {
66 newnode->next = h->htable[hvalue];
67 h->htable[hvalue] = newnode;
68 }
69
70 h->nel++;
71 return 0;
72}
73
74void *hashtab_search(struct hashtab *h, const void *key)
75{
76 u32 hvalue;
77 struct hashtab_node *cur;
78
79 if (!h)
80 return NULL;
81
82 hvalue = h->hash_value(h, key);
83 cur = h->htable[hvalue];
84 while (cur && h->keycmp(h, key, cur->key) > 0)
85 cur = cur->next;
86
87 if (cur == NULL || (h->keycmp(h, key, cur->key) != 0))
88 return NULL;
89
90 return cur->datum;
91}
92
93void hashtab_destroy(struct hashtab *h)
94{
95 u32 i;
96 struct hashtab_node *cur, *temp;
97
98 if (!h)
99 return;
100
101 for (i = 0; i < h->size; i++) {
102 cur = h->htable[i];
103 while (cur) {
104 temp = cur;
105 cur = cur->next;
106 kfree(temp);
107 }
108 h->htable[i] = NULL;
109 }
110
111 kfree(h->htable);
112 h->htable = NULL;
113
114 kfree(h);
115}
116
117int hashtab_map(struct hashtab *h,
118 int (*apply)(void *k, void *d, void *args),
119 void *args)
120{
121 u32 i;
122 int ret;
123 struct hashtab_node *cur;
124
125 if (!h)
126 return 0;
127
128 for (i = 0; i < h->size; i++) {
129 cur = h->htable[i];
130 while (cur) {
131 ret = apply(cur->key, cur->datum, args);
132 if (ret)
133 return ret;
134 cur = cur->next;
135 }
136 }
137 return 0;
138}
139
140
141void hashtab_stat(struct hashtab *h, struct hashtab_info *info)
142{
143 u32 i, chain_len, slots_used, max_chain_len;
144 struct hashtab_node *cur;
145
146 slots_used = 0;
147 max_chain_len = 0;
148 for (slots_used = max_chain_len = i = 0; i < h->size; i++) {
149 cur = h->htable[i];
150 if (cur) {
151 slots_used++;
152 chain_len = 0;
153 while (cur) {
154 chain_len++;
155 cur = cur->next;
156 }
157
158 if (chain_len > max_chain_len)
159 max_chain_len = chain_len;
160 }
161 }
162
163 info->slots_used = slots_used;
164 info->max_chain_len = max_chain_len;
165}