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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}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Implementation of the hash table type.
4 *
5 * Author : Stephen Smalley, <stephen.smalley.work@gmail.com>
6 */
7
8#include <linux/kernel.h>
9#include <linux/slab.h>
10#include <linux/errno.h>
11#include "hashtab.h"
12#include "security.h"
13
14static struct kmem_cache *hashtab_node_cachep __ro_after_init;
15
16/*
17 * Here we simply round the number of elements up to the nearest power of two.
18 * I tried also other options like rounding down or rounding to the closest
19 * power of two (up or down based on which is closer), but I was unable to
20 * find any significant difference in lookup/insert performance that would
21 * justify switching to a different (less intuitive) formula. It could be that
22 * a different formula is actually more optimal, but any future changes here
23 * should be supported with performance/memory usage data.
24 *
25 * The total memory used by the htable arrays (only) with Fedora policy loaded
26 * is approximately 163 KB at the time of writing.
27 */
28static u32 hashtab_compute_size(u32 nel)
29{
30 return nel == 0 ? 0 : roundup_pow_of_two(nel);
31}
32
33int hashtab_init(struct hashtab *h, u32 nel_hint)
34{
35 u32 size = hashtab_compute_size(nel_hint);
36
37 /* should already be zeroed, but better be safe */
38 h->nel = 0;
39 h->size = 0;
40 h->htable = NULL;
41
42 if (size) {
43 h->htable = kcalloc(size, sizeof(*h->htable), GFP_KERNEL);
44 if (!h->htable)
45 return -ENOMEM;
46 h->size = size;
47 }
48 return 0;
49}
50
51int __hashtab_insert(struct hashtab *h, struct hashtab_node **dst, void *key,
52 void *datum)
53{
54 struct hashtab_node *newnode;
55
56 newnode = kmem_cache_zalloc(hashtab_node_cachep, GFP_KERNEL);
57 if (!newnode)
58 return -ENOMEM;
59 newnode->key = key;
60 newnode->datum = datum;
61 newnode->next = *dst;
62 *dst = newnode;
63
64 h->nel++;
65 return 0;
66}
67
68void hashtab_destroy(struct hashtab *h)
69{
70 u32 i;
71 struct hashtab_node *cur, *temp;
72
73 for (i = 0; i < h->size; i++) {
74 cur = h->htable[i];
75 while (cur) {
76 temp = cur;
77 cur = cur->next;
78 kmem_cache_free(hashtab_node_cachep, temp);
79 }
80 h->htable[i] = NULL;
81 }
82
83 kfree(h->htable);
84 h->htable = NULL;
85}
86
87int hashtab_map(struct hashtab *h, 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#ifdef CONFIG_SECURITY_SELINUX_DEBUG
107void hashtab_stat(struct hashtab *h, struct hashtab_info *info)
108{
109 u32 i, chain_len, slots_used, max_chain_len;
110 u64 chain2_len_sum;
111 struct hashtab_node *cur;
112
113 slots_used = 0;
114 max_chain_len = 0;
115 chain2_len_sum = 0;
116 for (i = 0; i < h->size; i++) {
117 cur = h->htable[i];
118 if (cur) {
119 slots_used++;
120 chain_len = 0;
121 while (cur) {
122 chain_len++;
123 cur = cur->next;
124 }
125
126 if (chain_len > max_chain_len)
127 max_chain_len = chain_len;
128
129 chain2_len_sum += (u64)chain_len * chain_len;
130 }
131 }
132
133 info->slots_used = slots_used;
134 info->max_chain_len = max_chain_len;
135 info->chain2_len_sum = chain2_len_sum;
136}
137#endif /* CONFIG_SECURITY_SELINUX_DEBUG */
138
139int hashtab_duplicate(struct hashtab *new, struct hashtab *orig,
140 int (*copy)(struct hashtab_node *new,
141 struct hashtab_node *orig, void *args),
142 int (*destroy)(void *k, void *d, void *args), void *args)
143{
144 struct hashtab_node *cur, *tmp, *tail;
145 u32 i;
146 int rc;
147
148 memset(new, 0, sizeof(*new));
149
150 new->htable = kcalloc(orig->size, sizeof(*new->htable), GFP_KERNEL);
151 if (!new->htable)
152 return -ENOMEM;
153
154 new->size = orig->size;
155
156 for (i = 0; i < orig->size; i++) {
157 tail = NULL;
158 for (cur = orig->htable[i]; cur; cur = cur->next) {
159 tmp = kmem_cache_zalloc(hashtab_node_cachep,
160 GFP_KERNEL);
161 if (!tmp)
162 goto error;
163 rc = copy(tmp, cur, args);
164 if (rc) {
165 kmem_cache_free(hashtab_node_cachep, tmp);
166 goto error;
167 }
168 tmp->next = NULL;
169 if (!tail)
170 new->htable[i] = tmp;
171 else
172 tail->next = tmp;
173 tail = tmp;
174 new->nel++;
175 }
176 }
177
178 return 0;
179
180error:
181 for (i = 0; i < new->size; i++) {
182 for (cur = new->htable[i]; cur; cur = tmp) {
183 tmp = cur->next;
184 destroy(cur->key, cur->datum, args);
185 kmem_cache_free(hashtab_node_cachep, cur);
186 }
187 }
188 kfree(new->htable);
189 memset(new, 0, sizeof(*new));
190 return -ENOMEM;
191}
192
193void __init hashtab_cache_init(void)
194{
195 hashtab_node_cachep = kmem_cache_create("hashtab_node",
196 sizeof(struct hashtab_node), 0,
197 SLAB_PANIC, NULL);
198}