security/selinux/ss/hashtab.c

   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
  13 static struct kmem_cache *hashtab_node_cachep;
  14
  15 struct 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
  42 int 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
  80 void *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
  99 void 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
 123 int 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
 147 void 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
 173 void __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 }