1 files changed, 192 insertions, 0 deletions
diff --git a/security/selinux/ss/hashtab.c b/security/selinux/ss/hashtab.c
new file mode 100644
index 000000000..3fb8f9026
--- /dev/null
+++ b/security/selinux/ss/hashtab.c
@@ -0,0 +1,192 @@
+// 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)
+{
+	u32 size = hashtab_compute_size(nel_hint);
+
+	/* should already be zeroed, but better be safe */
+	h->nel = 0;
+	h->size = 0;
+	h->htable = NULL;
+
+	if (size) {
+		h->htable = kcalloc(size, sizeof(*h->htable), GFP_KERNEL);
+		if (!h->htable)
+			return -ENOMEM;
+		h->size = size;
+	}
+	return 0;
+}
+
+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);
+		}
+	}
+	kfree(new->htable);
+	memset(new, 0, sizeof(*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);
+}