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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// 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 <linux/sched.h>
11#include "hashtab.h"
12
13static struct kmem_cache *hashtab_node_cachep;
14
15struct hashtab *hashtab_create(u32 (*hash_value)(struct hashtab *h, const void *key),
16 int (*keycmp)(struct hashtab *h, const void *key1, const void *key2),
17 u32 size)
18{
19 struct hashtab *p;
20 u32 i;
21
22 p = kzalloc(sizeof(*p), GFP_KERNEL);
23 if (!p)
24 return p;
25
26 p->size = size;
27 p->nel = 0;
28 p->hash_value = hash_value;
29 p->keycmp = keycmp;
30 p->htable = kmalloc_array(size, sizeof(*p->htable), GFP_KERNEL);
31 if (!p->htable) {
32 kfree(p);
33 return NULL;
34 }
35
36 for (i = 0; i < size; i++)
37 p->htable[i] = NULL;
38
39 return p;
40}
41
42int hashtab_insert(struct hashtab *h, void *key, void *datum)
43{
44 u32 hvalue;
45 struct hashtab_node *prev, *cur, *newnode;
46
47 cond_resched();
48
49 if (!h || h->nel == HASHTAB_MAX_NODES)
50 return -EINVAL;
51
52 hvalue = h->hash_value(h, key);
53 prev = NULL;
54 cur = h->htable[hvalue];
55 while (cur && h->keycmp(h, key, cur->key) > 0) {
56 prev = cur;
57 cur = cur->next;
58 }
59
60 if (cur && (h->keycmp(h, key, cur->key) == 0))
61 return -EEXIST;
62
63 newnode = kmem_cache_zalloc(hashtab_node_cachep, GFP_KERNEL);
64 if (!newnode)
65 return -ENOMEM;
66 newnode->key = key;
67 newnode->datum = datum;
68 if (prev) {
69 newnode->next = prev->next;
70 prev->next = newnode;
71 } else {
72 newnode->next = h->htable[hvalue];
73 h->htable[hvalue] = newnode;
74 }
75
76 h->nel++;
77 return 0;
78}
79
80void *hashtab_search(struct hashtab *h, const void *key)
81{
82 u32 hvalue;
83 struct hashtab_node *cur;
84
85 if (!h)
86 return NULL;
87
88 hvalue = h->hash_value(h, key);
89 cur = h->htable[hvalue];
90 while (cur && h->keycmp(h, key, cur->key) > 0)
91 cur = cur->next;
92
93 if (!cur || (h->keycmp(h, key, cur->key) != 0))
94 return NULL;
95
96 return cur->datum;
97}
98
99void hashtab_destroy(struct hashtab *h)
100{
101 u32 i;
102 struct hashtab_node *cur, *temp;
103
104 if (!h)
105 return;
106
107 for (i = 0; i < h->size; i++) {
108 cur = h->htable[i];
109 while (cur) {
110 temp = cur;
111 cur = cur->next;
112 kmem_cache_free(hashtab_node_cachep, temp);
113 }
114 h->htable[i] = NULL;
115 }
116
117 kfree(h->htable);
118 h->htable = NULL;
119
120 kfree(h);
121}
122
123int hashtab_map(struct hashtab *h,
124 int (*apply)(void *k, void *d, void *args),
125 void *args)
126{
127 u32 i;
128 int ret;
129 struct hashtab_node *cur;
130
131 if (!h)
132 return 0;
133
134 for (i = 0; i < h->size; i++) {
135 cur = h->htable[i];
136 while (cur) {
137 ret = apply(cur->key, cur->datum, args);
138 if (ret)
139 return ret;
140 cur = cur->next;
141 }
142 }
143 return 0;
144}
145
146
147void hashtab_stat(struct hashtab *h, struct hashtab_info *info)
148{
149 u32 i, chain_len, slots_used, max_chain_len;
150 struct hashtab_node *cur;
151
152 slots_used = 0;
153 max_chain_len = 0;
154 for (i = 0; i < h->size; i++) {
155 cur = h->htable[i];
156 if (cur) {
157 slots_used++;
158 chain_len = 0;
159 while (cur) {
160 chain_len++;
161 cur = cur->next;
162 }
163
164 if (chain_len > max_chain_len)
165 max_chain_len = chain_len;
166 }
167 }
168
169 info->slots_used = slots_used;
170 info->max_chain_len = max_chain_len;
171}
172
173void __init hashtab_cache_init(void)
174{
175 hashtab_node_cachep = kmem_cache_create("hashtab_node",
176 sizeof(struct hashtab_node),
177 0, SLAB_PANIC, NULL);
178}