| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * Implementation of the hash table type. |
| * |
| * Author : Stephen Smalley, <sds@tycho.nsa.gov> |
| */ |
| #include <linux/kernel.h> |
| #include <linux/slab.h> |
| #include <linux/errno.h> |
| #include "hashtab.h" |
| #include "security.h" |
| |
| static struct kmem_cache *hashtab_node_cachep __ro_after_init; |
| |
| /* |
| * Here we simply round the number of elements up to the nearest power of two. |
| * I tried also other options like rounding down or rounding to the closest |
| * power of two (up or down based on which is closer), but I was unable to |
| * find any significant difference in lookup/insert performance that would |
| * justify switching to a different (less intuitive) formula. It could be that |
| * a different formula is actually more optimal, but any future changes here |
| * should be supported with performance/memory usage data. |
| * |
| * The total memory used by the htable arrays (only) with Fedora policy loaded |
| * is approximately 163 KB at the time of writing. |
| */ |
| static u32 hashtab_compute_size(u32 nel) |
| { |
| return nel == 0 ? 0 : roundup_pow_of_two(nel); |
| } |
| |
| int hashtab_init(struct hashtab *h, u32 nel_hint) |
| { |
| h->size = hashtab_compute_size(nel_hint); |
| h->nel = 0; |
| if (!h->size) |
| return 0; |
| |
| h->htable = kcalloc(h->size, sizeof(*h->htable), GFP_KERNEL); |
| return h->htable ? 0 : -ENOMEM; |
| } |
| |
| int __hashtab_insert(struct hashtab *h, struct hashtab_node **dst, |
| void *key, void *datum) |
| { |
| struct hashtab_node *newnode; |
| |
| newnode = kmem_cache_zalloc(hashtab_node_cachep, GFP_KERNEL); |
| if (!newnode) |
| return -ENOMEM; |
| newnode->key = key; |
| newnode->datum = datum; |
| newnode->next = *dst; |
| *dst = newnode; |
| |
| h->nel++; |
| return 0; |
| } |
| |
| void hashtab_destroy(struct hashtab *h) |
| { |
| u32 i; |
| struct hashtab_node *cur, *temp; |
| |
| for (i = 0; i < h->size; i++) { |
| cur = h->htable[i]; |
| while (cur) { |
| temp = cur; |
| cur = cur->next; |
| kmem_cache_free(hashtab_node_cachep, temp); |
| } |
| h->htable[i] = NULL; |
| } |
| |
| kfree(h->htable); |
| h->htable = NULL; |
| } |
| |
| int hashtab_map(struct hashtab *h, |
| int (*apply)(void *k, void *d, void *args), |
| void *args) |
| { |
| u32 i; |
| int ret; |
| struct hashtab_node *cur; |
| |
| for (i = 0; i < h->size; i++) { |
| cur = h->htable[i]; |
| while (cur) { |
| ret = apply(cur->key, cur->datum, args); |
| if (ret) |
| return ret; |
| cur = cur->next; |
| } |
| } |
| return 0; |
| } |
| |
| |
| void hashtab_stat(struct hashtab *h, struct hashtab_info *info) |
| { |
| u32 i, chain_len, slots_used, max_chain_len; |
| struct hashtab_node *cur; |
| |
| slots_used = 0; |
| max_chain_len = 0; |
| for (i = 0; i < h->size; i++) { |
| cur = h->htable[i]; |
| if (cur) { |
| slots_used++; |
| chain_len = 0; |
| while (cur) { |
| chain_len++; |
| cur = cur->next; |
| } |
| |
| if (chain_len > max_chain_len) |
| max_chain_len = chain_len; |
| } |
| } |
| |
| info->slots_used = slots_used; |
| info->max_chain_len = max_chain_len; |
| } |
| |
| int hashtab_duplicate(struct hashtab *new, struct hashtab *orig, |
| int (*copy)(struct hashtab_node *new, |
| struct hashtab_node *orig, void *args), |
| int (*destroy)(void *k, void *d, void *args), |
| void *args) |
| { |
| struct hashtab_node *cur, *tmp, *tail; |
| int i, rc; |
| |
| memset(new, 0, sizeof(*new)); |
| |
| new->htable = kcalloc(orig->size, sizeof(*new->htable), GFP_KERNEL); |
| if (!new->htable) |
| return -ENOMEM; |
| |
| new->size = orig->size; |
| |
| for (i = 0; i < orig->size; i++) { |
| tail = NULL; |
| for (cur = orig->htable[i]; cur; cur = cur->next) { |
| tmp = kmem_cache_zalloc(hashtab_node_cachep, |
| GFP_KERNEL); |
| if (!tmp) |
| goto error; |
| rc = copy(tmp, cur, args); |
| if (rc) { |
| kmem_cache_free(hashtab_node_cachep, tmp); |
| goto error; |
| } |
| tmp->next = NULL; |
| if (!tail) |
| new->htable[i] = tmp; |
| else |
| tail->next = tmp; |
| tail = tmp; |
| new->nel++; |
| } |
| } |
| |
| return 0; |
| |
| error: |
| for (i = 0; i < new->size; i++) { |
| for (cur = new->htable[i]; cur; cur = tmp) { |
| tmp = cur->next; |
| destroy(cur->key, cur->datum, args); |
| kmem_cache_free(hashtab_node_cachep, cur); |
| } |
| } |
| kmem_cache_free(hashtab_node_cachep, new); |
| return -ENOMEM; |
| } |
| |
| void __init hashtab_cache_init(void) |
| { |
| hashtab_node_cachep = kmem_cache_create("hashtab_node", |
| sizeof(struct hashtab_node), |
| 0, SLAB_PANIC, NULL); |
| } |