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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 <linux/sched.h>
10#include "hashtab.h"
11
12struct hashtab *hashtab_create(u32 (*hash_value)(struct hashtab *h, const void *key),
13 int (*keycmp)(struct hashtab *h, const void *key1, const void *key2),
14 u32 size)
15{
16 struct hashtab *p;
17 u32 i;
18
19 p = kzalloc(sizeof(*p), GFP_KERNEL);
20 if (p == NULL)
21 return p;
22
23 p->size = size;
24 p->nel = 0;
25 p->hash_value = hash_value;
26 p->keycmp = keycmp;
27 p->htable = kmalloc(sizeof(*(p->htable)) * size, GFP_KERNEL);
28 if (p->htable == NULL) {
29 kfree(p);
30 return NULL;
31 }
32
33 for (i = 0; i < size; i++)
34 p->htable[i] = NULL;
35
36 return p;
37}
38
39int hashtab_insert(struct hashtab *h, void *key, void *datum)
40{
41 u32 hvalue;
42 struct hashtab_node *prev, *cur, *newnode;
43
44 cond_resched();
45
46 if (!h || h->nel == HASHTAB_MAX_NODES)
47 return -EINVAL;
48
49 hvalue = h->hash_value(h, key);
50 prev = NULL;
51 cur = h->htable[hvalue];
52 while (cur && h->keycmp(h, key, cur->key) > 0) {
53 prev = cur;
54 cur = cur->next;
55 }
56
57 if (cur && (h->keycmp(h, key, cur->key) == 0))
58 return -EEXIST;
59
60 newnode = kzalloc(sizeof(*newnode), GFP_KERNEL);
61 if (newnode == NULL)
62 return -ENOMEM;
63 newnode->key = key;
64 newnode->datum = datum;
65 if (prev) {
66 newnode->next = prev->next;
67 prev->next = newnode;
68 } else {
69 newnode->next = h->htable[hvalue];
70 h->htable[hvalue] = newnode;
71 }
72
73 h->nel++;
74 return 0;
75}
76
77void *hashtab_search(struct hashtab *h, const void *key)
78{
79 u32 hvalue;
80 struct hashtab_node *cur;
81
82 if (!h)
83 return NULL;
84
85 hvalue = h->hash_value(h, key);
86 cur = h->htable[hvalue];
87 while (cur && h->keycmp(h, key, cur->key) > 0)
88 cur = cur->next;
89
90 if (cur == NULL || (h->keycmp(h, key, cur->key) != 0))
91 return NULL;
92
93 return cur->datum;
94}
95
96void hashtab_destroy(struct hashtab *h)
97{
98 u32 i;
99 struct hashtab_node *cur, *temp;
100
101 if (!h)
102 return;
103
104 for (i = 0; i < h->size; i++) {
105 cur = h->htable[i];
106 while (cur) {
107 temp = cur;
108 cur = cur->next;
109 kfree(temp);
110 }
111 h->htable[i] = NULL;
112 }
113
114 kfree(h->htable);
115 h->htable = NULL;
116
117 kfree(h);
118}
119
120int hashtab_map(struct hashtab *h,
121 int (*apply)(void *k, void *d, void *args),
122 void *args)
123{
124 u32 i;
125 int ret;
126 struct hashtab_node *cur;
127
128 if (!h)
129 return 0;
130
131 for (i = 0; i < h->size; i++) {
132 cur = h->htable[i];
133 while (cur) {
134 ret = apply(cur->key, cur->datum, args);
135 if (ret)
136 return ret;
137 cur = cur->next;
138 }
139 }
140 return 0;
141}
142
143
144void hashtab_stat(struct hashtab *h, struct hashtab_info *info)
145{
146 u32 i, chain_len, slots_used, max_chain_len;
147 struct hashtab_node *cur;
148
149 slots_used = 0;
150 max_chain_len = 0;
151 for (slots_used = max_chain_len = i = 0; i < h->size; i++) {
152 cur = h->htable[i];
153 if (cur) {
154 slots_used++;
155 chain_len = 0;
156 while (cur) {
157 chain_len++;
158 cur = cur->next;
159 }
160
161 if (chain_len > max_chain_len)
162 max_chain_len = chain_len;
163 }
164 }
165
166 info->slots_used = slots_used;
167 info->max_chain_len = max_chain_len;
168}
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, 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 const struct hashtab_node *orig_cur;
145 struct hashtab_node *cur, *tmp, *tail;
146 u32 i;
147 int rc;
148
149 memset(new, 0, sizeof(*new));
150
151 new->htable = kcalloc(orig->size, sizeof(*new->htable), GFP_KERNEL);
152 if (!new->htable)
153 return -ENOMEM;
154
155 new->size = orig->size;
156
157 for (i = 0; i < orig->size; i++) {
158 tail = NULL;
159 for (orig_cur = orig->htable[i]; orig_cur;
160 orig_cur = orig_cur->next) {
161 tmp = kmem_cache_zalloc(hashtab_node_cachep,
162 GFP_KERNEL);
163 if (!tmp)
164 goto error;
165 rc = copy(tmp, orig_cur, args);
166 if (rc) {
167 kmem_cache_free(hashtab_node_cachep, tmp);
168 goto error;
169 }
170 tmp->next = NULL;
171 if (!tail)
172 new->htable[i] = tmp;
173 else
174 tail->next = tmp;
175 tail = tmp;
176 new->nel++;
177 }
178 }
179
180 return 0;
181
182error:
183 for (i = 0; i < new->size; i++) {
184 for (cur = new->htable[i]; cur; cur = tmp) {
185 tmp = cur->next;
186 destroy(cur->key, cur->datum, args);
187 kmem_cache_free(hashtab_node_cachep, cur);
188 }
189 }
190 kfree(new->htable);
191 memset(new, 0, sizeof(*new));
192 return -ENOMEM;
193}
194
195void __init hashtab_cache_init(void)
196{
197 hashtab_node_cachep = KMEM_CACHE(hashtab_node, SLAB_PANIC);
198}