1 files changed, 306 insertions, 0 deletions
diff --git a/security/selinux/ss/sidtab.c b/security/selinux/ss/sidtab.c
new file mode 100644
index 000000000..fd75a12fa
--- /dev/null
+++ b/security/selinux/ss/sidtab.c
@@ -0,0 +1,306 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Implementation of the SID table type.
+ *
+ * Author : Stephen Smalley, <sds@tycho.nsa.gov>
+ */
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/errno.h>
+#include "flask.h"
+#include "security.h"
+#include "sidtab.h"
+
+#define SIDTAB_HASH(sid) \
+(sid & SIDTAB_HASH_MASK)
+
+int sidtab_init(struct sidtab *s)
+{
+	int i;
+
+	s->htable = kmalloc_array(SIDTAB_SIZE, sizeof(*s->htable), GFP_ATOMIC);
+	if (!s->htable)
+		return -ENOMEM;
+	for (i = 0; i < SIDTAB_SIZE; i++)
+		s->htable[i] = NULL;
+	s->nel = 0;
+	s->next_sid = 1;
+	s->shutdown = 0;
+	spin_lock_init(&s->lock);
+	return 0;
+}
+
+int sidtab_insert(struct sidtab *s, u32 sid, struct context *context)
+{
+	int hvalue;
+	struct sidtab_node *prev, *cur, *newnode;
+
+	if (!s)
+		return -ENOMEM;
+
+	hvalue = SIDTAB_HASH(sid);
+	prev = NULL;
+	cur = s->htable[hvalue];
+	while (cur && sid > cur->sid) {
+		prev = cur;
+		cur = cur->next;
+	}
+
+	if (cur && sid == cur->sid)
+		return -EEXIST;
+
+	newnode = kmalloc(sizeof(*newnode), GFP_ATOMIC);
+	if (!newnode)
+		return -ENOMEM;
+
+	newnode->sid = sid;
+	if (context_cpy(&newnode->context, context)) {
+		kfree(newnode);
+		return -ENOMEM;
+	}
+
+	if (prev) {
+		newnode->next = prev->next;
+		wmb();
+		prev->next = newnode;
+	} else {
+		newnode->next = s->htable[hvalue];
+		wmb();
+		s->htable[hvalue] = newnode;
+	}
+
+	s->nel++;
+	if (sid >= s->next_sid)
+		s->next_sid = sid + 1;
+	return 0;
+}
+
+static struct context *sidtab_search_core(struct sidtab *s, u32 sid, int force)
+{
+	int hvalue;
+	struct sidtab_node *cur;
+
+	if (!s)
+		return NULL;
+
+	hvalue = SIDTAB_HASH(sid);
+	cur = s->htable[hvalue];
+	while (cur && sid > cur->sid)
+		cur = cur->next;
+
+	if (force && cur && sid == cur->sid && cur->context.len)
+		return &cur->context;
+
+	if (!cur || sid != cur->sid || cur->context.len) {
+		/* Remap invalid SIDs to the unlabeled SID. */
+		sid = SECINITSID_UNLABELED;
+		hvalue = SIDTAB_HASH(sid);
+		cur = s->htable[hvalue];
+		while (cur && sid > cur->sid)
+			cur = cur->next;
+		if (!cur || sid != cur->sid)
+			return NULL;
+	}
+
+	return &cur->context;
+}
+
+struct context *sidtab_search(struct sidtab *s, u32 sid)
+{
+	return sidtab_search_core(s, sid, 0);
+}
+
+struct context *sidtab_search_force(struct sidtab *s, u32 sid)
+{
+	return sidtab_search_core(s, sid, 1);
+}
+
+int sidtab_map(struct sidtab *s,
+	       int (*apply) (u32 sid,
+			     struct context *context,
+			     void *args),
+	       void *args)
+{
+	int i, rc = 0;
+	struct sidtab_node *cur;
+
+	if (!s)
+		goto out;
+
+	for (i = 0; i < SIDTAB_SIZE; i++) {
+		cur = s->htable[i];
+		while (cur) {
+			rc = apply(cur->sid, &cur->context, args);
+			if (rc)
+				goto out;
+			cur = cur->next;
+		}
+	}
+out:
+	return rc;
+}
+
+static void sidtab_update_cache(struct sidtab *s, struct sidtab_node *n, int loc)
+{
+	BUG_ON(loc >= SIDTAB_CACHE_LEN);
+
+	while (loc > 0) {
+		s->cache[loc] = s->cache[loc - 1];
+		loc--;
+	}
+	s->cache[0] = n;
+}
+
+static inline u32 sidtab_search_context(struct sidtab *s,
+						  struct context *context)
+{
+	int i;
+	struct sidtab_node *cur;
+
+	for (i = 0; i < SIDTAB_SIZE; i++) {
+		cur = s->htable[i];
+		while (cur) {
+			if (context_cmp(&cur->context, context)) {
+				sidtab_update_cache(s, cur, SIDTAB_CACHE_LEN - 1);
+				return cur->sid;
+			}
+			cur = cur->next;
+		}
+	}
+	return 0;
+}
+
+static inline u32 sidtab_search_cache(struct sidtab *s, struct context *context)
+{
+	int i;
+	struct sidtab_node *node;
+
+	for (i = 0; i < SIDTAB_CACHE_LEN; i++) {
+		node = s->cache[i];
+		if (unlikely(!node))
+			return 0;
+		if (context_cmp(&node->context, context)) {
+			sidtab_update_cache(s, node, i);
+			return node->sid;
+		}
+	}
+	return 0;
+}
+
+int sidtab_context_to_sid(struct sidtab *s,
+			  struct context *context,
+			  u32 *out_sid)
+{
+	u32 sid;
+	int ret = 0;
+	unsigned long flags;
+
+	*out_sid = SECSID_NULL;
+
+	sid  = sidtab_search_cache(s, context);
+	if (!sid)
+		sid = sidtab_search_context(s, context);
+	if (!sid) {
+		spin_lock_irqsave(&s->lock, flags);
+		/* Rescan now that we hold the lock. */
+		sid = sidtab_search_context(s, context);
+		if (sid)
+			goto unlock_out;
+		/* No SID exists for the context.  Allocate a new one. */
+		if (s->next_sid == UINT_MAX || s->shutdown) {
+			ret = -ENOMEM;
+			goto unlock_out;
+		}
+		sid = s->next_sid++;
+		if (context->len)
+			pr_info("SELinux:  Context %s is not valid (left unmapped).\n",
+			       context->str);
+		ret = sidtab_insert(s, sid, context);
+		if (ret)
+			s->next_sid--;
+unlock_out:
+		spin_unlock_irqrestore(&s->lock, flags);
+	}
+
+	if (ret)
+		return ret;
+
+	*out_sid = sid;
+	return 0;
+}
+
+void sidtab_hash_eval(struct sidtab *h, char *tag)
+{
+	int i, chain_len, slots_used, max_chain_len;
+	struct sidtab_node *cur;
+
+	slots_used = 0;
+	max_chain_len = 0;
+	for (i = 0; i < SIDTAB_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;
+		}
+	}
+
+	pr_debug("%s:  %d entries and %d/%d buckets used, longest "
+	       "chain length %d\n", tag, h->nel, slots_used, SIDTAB_SIZE,
+	       max_chain_len);
+}
+
+void sidtab_destroy(struct sidtab *s)
+{
+	int i;
+	struct sidtab_node *cur, *temp;
+
+	if (!s)
+		return;
+
+	for (i = 0; i < SIDTAB_SIZE; i++) {
+		cur = s->htable[i];
+		while (cur) {
+			temp = cur;
+			cur = cur->next;
+			context_destroy(&temp->context);
+			kfree(temp);
+		}
+		s->htable[i] = NULL;
+	}
+	kfree(s->htable);
+	s->htable = NULL;
+	s->nel = 0;
+	s->next_sid = 1;
+}
+
+void sidtab_set(struct sidtab *dst, struct sidtab *src)
+{
+	unsigned long flags;
+	int i;
+
+	spin_lock_irqsave(&src->lock, flags);
+	dst->htable = src->htable;
+	dst->nel = src->nel;
+	dst->next_sid = src->next_sid;
+	dst->shutdown = 0;
+	for (i = 0; i < SIDTAB_CACHE_LEN; i++)
+		dst->cache[i] = NULL;
+	spin_unlock_irqrestore(&src->lock, flags);
+}
+
+void sidtab_shutdown(struct sidtab *s)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&s->lock, flags);
+	s->shutdown = 1;
+	spin_unlock_irqrestore(&s->lock, flags);
+}