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