diff --git a/security/keys/keyring.c b/security/keys/keyring.c
new file mode 100644
index 0000000..e2ab4f8
--- /dev/null
+++ b/security/keys/keyring.c
@@ -0,0 +1,895 @@
+/* keyring.c: keyring handling
+ *
+ * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/seq_file.h>
+#include <linux/err.h>
+#include <asm/uaccess.h>
+#include "internal.h"
+
+/*
+ * when plumbing the depths of the key tree, this sets a hard limit set on how
+ * deep we're willing to go
+ */
+#define KEYRING_SEARCH_MAX_DEPTH 6
+
+/*
+ * we keep all named keyrings in a hash to speed looking them up
+ */
+#define KEYRING_NAME_HASH_SIZE	(1 << 5)
+
+static struct list_head	keyring_name_hash[KEYRING_NAME_HASH_SIZE];
+static DEFINE_RWLOCK(keyring_name_lock);
+
+static inline unsigned keyring_hash(const char *desc)
+{
+	unsigned bucket = 0;
+
+	for (; *desc; desc++)
+		bucket += (unsigned char) *desc;
+
+	return bucket & (KEYRING_NAME_HASH_SIZE - 1);
+}
+
+/*
+ * the keyring type definition
+ */
+static int keyring_instantiate(struct key *keyring,
+			       const void *data, size_t datalen);
+static int keyring_duplicate(struct key *keyring, const struct key *source);
+static int keyring_match(const struct key *keyring, const void *criterion);
+static void keyring_destroy(struct key *keyring);
+static void keyring_describe(const struct key *keyring, struct seq_file *m);
+static long keyring_read(const struct key *keyring,
+			 char __user *buffer, size_t buflen);
+
+struct key_type key_type_keyring = {
+	.name		= "keyring",
+	.def_datalen	= sizeof(struct keyring_list),
+	.instantiate	= keyring_instantiate,
+	.duplicate	= keyring_duplicate,
+	.match		= keyring_match,
+	.destroy	= keyring_destroy,
+	.describe	= keyring_describe,
+	.read		= keyring_read,
+};
+
+/*
+ * semaphore to serialise link/link calls to prevent two link calls in parallel
+ * introducing a cycle
+ */
+DECLARE_RWSEM(keyring_serialise_link_sem);
+
+/*****************************************************************************/
+/*
+ * publish the name of a keyring so that it can be found by name (if it has
+ * one)
+ */
+void keyring_publish_name(struct key *keyring)
+{
+	int bucket;
+
+	if (keyring->description) {
+		bucket = keyring_hash(keyring->description);
+
+		write_lock(&keyring_name_lock);
+
+		if (!keyring_name_hash[bucket].next)
+			INIT_LIST_HEAD(&keyring_name_hash[bucket]);
+
+		list_add_tail(&keyring->type_data.link,
+			      &keyring_name_hash[bucket]);
+
+		write_unlock(&keyring_name_lock);
+	}
+
+} /* end keyring_publish_name() */
+
+/*****************************************************************************/
+/*
+ * initialise a keyring
+ * - we object if we were given any data
+ */
+static int keyring_instantiate(struct key *keyring,
+			       const void *data, size_t datalen)
+{
+	int ret;
+
+	ret = -EINVAL;
+	if (datalen == 0) {
+		/* make the keyring available by name if it has one */
+		keyring_publish_name(keyring);
+		ret = 0;
+	}
+
+	return ret;
+
+} /* end keyring_instantiate() */
+
+/*****************************************************************************/
+/*
+ * duplicate the list of subscribed keys from a source keyring into this one
+ */
+static int keyring_duplicate(struct key *keyring, const struct key *source)
+{
+	struct keyring_list *sklist, *klist;
+	unsigned max;
+	size_t size;
+	int loop, ret;
+
+	const unsigned limit =
+		(PAGE_SIZE - sizeof(*klist)) / sizeof(struct key);
+
+	ret = 0;
+	sklist = source->payload.subscriptions;
+
+	if (sklist && sklist->nkeys > 0) {
+		max = sklist->nkeys;
+		BUG_ON(max > limit);
+
+		max = (max + 3) & ~3;
+		if (max > limit)
+			max = limit;
+
+		ret = -ENOMEM;
+		size = sizeof(*klist) + sizeof(struct key) * max;
+		klist = kmalloc(size, GFP_KERNEL);
+		if (!klist)
+			goto error;
+
+		klist->maxkeys = max;
+		klist->nkeys = sklist->nkeys;
+		memcpy(klist->keys,
+		       sklist->keys,
+		       sklist->nkeys * sizeof(struct key));
+
+		for (loop = klist->nkeys - 1; loop >= 0; loop--)
+			atomic_inc(&klist->keys[loop]->usage);
+
+		keyring->payload.subscriptions = klist;
+		ret = 0;
+	}
+
+ error:
+	return ret;
+
+} /* end keyring_duplicate() */
+
+/*****************************************************************************/
+/*
+ * match keyrings on their name
+ */
+static int keyring_match(const struct key *keyring, const void *description)
+{
+	return keyring->description &&
+		strcmp(keyring->description, description) == 0;
+
+} /* end keyring_match() */
+
+/*****************************************************************************/
+/*
+ * dispose of the data dangling from the corpse of a keyring
+ */
+static void keyring_destroy(struct key *keyring)
+{
+	struct keyring_list *klist;
+	int loop;
+
+	if (keyring->description) {
+		write_lock(&keyring_name_lock);
+		list_del(&keyring->type_data.link);
+		write_unlock(&keyring_name_lock);
+	}
+
+	klist = keyring->payload.subscriptions;
+	if (klist) {
+		for (loop = klist->nkeys - 1; loop >= 0; loop--)
+			key_put(klist->keys[loop]);
+		kfree(klist);
+	}
+
+} /* end keyring_destroy() */
+
+/*****************************************************************************/
+/*
+ * describe the keyring
+ */
+static void keyring_describe(const struct key *keyring, struct seq_file *m)
+{
+	struct keyring_list *klist;
+
+	if (keyring->description) {
+		seq_puts(m, keyring->description);
+	}
+	else {
+		seq_puts(m, "[anon]");
+	}
+
+	klist = keyring->payload.subscriptions;
+	if (klist)
+		seq_printf(m, ": %u/%u", klist->nkeys, klist->maxkeys);
+	else
+		seq_puts(m, ": empty");
+
+} /* end keyring_describe() */
+
+/*****************************************************************************/
+/*
+ * read a list of key IDs from the keyring's contents
+ */
+static long keyring_read(const struct key *keyring,
+			 char __user *buffer, size_t buflen)
+{
+	struct keyring_list *klist;
+	struct key *key;
+	size_t qty, tmp;
+	int loop, ret;
+
+	ret = 0;
+	klist = keyring->payload.subscriptions;
+
+	if (klist) {
+		/* calculate how much data we could return */
+		qty = klist->nkeys * sizeof(key_serial_t);
+
+		if (buffer && buflen > 0) {
+			if (buflen > qty)
+				buflen = qty;
+
+			/* copy the IDs of the subscribed keys into the
+			 * buffer */
+			ret = -EFAULT;
+
+			for (loop = 0; loop < klist->nkeys; loop++) {
+				key = klist->keys[loop];
+
+				tmp = sizeof(key_serial_t);
+				if (tmp > buflen)
+					tmp = buflen;
+
+				if (copy_to_user(buffer,
+						 &key->serial,
+						 tmp) != 0)
+					goto error;
+
+				buflen -= tmp;
+				if (buflen == 0)
+					break;
+				buffer += tmp;
+			}
+		}
+
+		ret = qty;
+	}
+
+ error:
+	return ret;
+
+} /* end keyring_read() */
+
+/*****************************************************************************/
+/*
+ * allocate a keyring and link into the destination keyring
+ */
+struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
+			  int not_in_quota, struct key *dest)
+{
+	struct key *keyring;
+	int ret;
+
+	keyring = key_alloc(&key_type_keyring, description,
+			    uid, gid, KEY_USR_ALL, not_in_quota);
+
+	if (!IS_ERR(keyring)) {
+		ret = key_instantiate_and_link(keyring, NULL, 0, dest);
+		if (ret < 0) {
+			key_put(keyring);
+			keyring = ERR_PTR(ret);
+		}
+	}
+
+	return keyring;
+
+} /* end keyring_alloc() */
+
+/*****************************************************************************/
+/*
+ * search the supplied keyring tree for a key that matches the criterion
+ * - perform a breadth-then-depth search up to the prescribed limit
+ * - we only find keys on which we have search permission
+ * - we use the supplied match function to see if the description (or other
+ *   feature of interest) matches
+ * - we readlock the keyrings as we search down the tree
+ * - we return -EAGAIN if we didn't find any matching key
+ * - we return -ENOKEY if we only found negative matching keys
+ */
+struct key *keyring_search_aux(struct key *keyring,
+			       struct key_type *type,
+			       const void *description,
+			       key_match_func_t match)
+{
+	struct {
+		struct key *keyring;
+		int kix;
+	} stack[KEYRING_SEARCH_MAX_DEPTH];
+
+	struct keyring_list *keylist;
+	struct timespec now;
+	struct key *key;
+	long err;
+	int sp, psp, kix;
+
+	key_check(keyring);
+
+	/* top keyring must have search permission to begin the search */
+	key = ERR_PTR(-EACCES);
+	if (!key_permission(keyring, KEY_SEARCH))
+		goto error;
+
+	key = ERR_PTR(-ENOTDIR);
+	if (keyring->type != &key_type_keyring)
+		goto error;
+
+	now = current_kernel_time();
+	err = -EAGAIN;
+	sp = 0;
+
+	/* start processing a new keyring */
+ descend:
+	read_lock(&keyring->lock);
+	if (keyring->flags & KEY_FLAG_REVOKED)
+		goto not_this_keyring;
+
+	keylist = keyring->payload.subscriptions;
+	if (!keylist)
+		goto not_this_keyring;
+
+	/* iterate through the keys in this keyring first */
+	for (kix = 0; kix < keylist->nkeys; kix++) {
+		key = keylist->keys[kix];
+
+		/* ignore keys not of this type */
+		if (key->type != type)
+			continue;
+
+		/* skip revoked keys and expired keys */
+		if (key->flags & KEY_FLAG_REVOKED)
+			continue;
+
+		if (key->expiry && now.tv_sec >= key->expiry)
+			continue;
+
+		/* keys that don't match */
+		if (!match(key, description))
+			continue;
+
+		/* key must have search permissions */
+		if (!key_permission(key, KEY_SEARCH))
+			continue;
+
+		/* we set a different error code if we find a negative key */
+		if (key->flags & KEY_FLAG_NEGATIVE) {
+			err = -ENOKEY;
+			continue;
+		}
+
+		goto found;
+	}
+
+	/* search through the keyrings nested in this one */
+	kix = 0;
+ ascend:
+	while (kix < keylist->nkeys) {
+		key = keylist->keys[kix];
+		if (key->type != &key_type_keyring)
+			goto next;
+
+		/* recursively search nested keyrings
+		 * - only search keyrings for which we have search permission
+		 */
+		if (sp >= KEYRING_SEARCH_MAX_DEPTH)
+			goto next;
+
+		if (!key_permission(key, KEY_SEARCH))
+			goto next;
+
+		/* evade loops in the keyring tree */
+		for (psp = 0; psp < sp; psp++)
+			if (stack[psp].keyring == keyring)
+				goto next;
+
+		/* stack the current position */
+		stack[sp].keyring = keyring;
+		stack[sp].kix = kix;
+		sp++;
+
+		/* begin again with the new keyring */
+		keyring = key;
+		goto descend;
+
+	next:
+		kix++;
+	}
+
+	/* the keyring we're looking at was disqualified or didn't contain a
+	 * matching key */
+ not_this_keyring:
+	read_unlock(&keyring->lock);
+
+	if (sp > 0) {
+		/* resume the processing of a keyring higher up in the tree */
+		sp--;
+		keyring = stack[sp].keyring;
+		keylist = keyring->payload.subscriptions;
+		kix = stack[sp].kix + 1;
+		goto ascend;
+	}
+
+	key = ERR_PTR(err);
+	goto error;
+
+	/* we found a viable match */
+ found:
+	atomic_inc(&key->usage);
+	read_unlock(&keyring->lock);
+
+	/* unwind the keyring stack */
+	while (sp > 0) {
+		sp--;
+		read_unlock(&stack[sp].keyring->lock);
+	}
+
+	key_check(key);
+ error:
+	return key;
+
+} /* end keyring_search_aux() */
+
+/*****************************************************************************/
+/*
+ * search the supplied keyring tree for a key that matches the criterion
+ * - perform a breadth-then-depth search up to the prescribed limit
+ * - we only find keys on which we have search permission
+ * - we readlock the keyrings as we search down the tree
+ * - we return -EAGAIN if we didn't find any matching key
+ * - we return -ENOKEY if we only found negative matching keys
+ */
+struct key *keyring_search(struct key *keyring,
+			   struct key_type *type,
+			   const char *description)
+{
+	return keyring_search_aux(keyring, type, description, type->match);
+
+} /* end keyring_search() */
+
+EXPORT_SYMBOL(keyring_search);
+
+/*****************************************************************************/
+/*
+ * search the given keyring only (no recursion)
+ * - keyring must be locked by caller
+ */
+struct key *__keyring_search_one(struct key *keyring,
+				 const struct key_type *ktype,
+				 const char *description,
+				 key_perm_t perm)
+{
+	struct keyring_list *klist;
+	struct key *key;
+	int loop;
+
+	klist = keyring->payload.subscriptions;
+	if (klist) {
+		for (loop = 0; loop < klist->nkeys; loop++) {
+			key = klist->keys[loop];
+
+			if (key->type == ktype &&
+			    key->type->match(key, description) &&
+			    key_permission(key, perm) &&
+			    !(key->flags & KEY_FLAG_REVOKED)
+			    )
+				goto found;
+		}
+	}
+
+	key = ERR_PTR(-ENOKEY);
+	goto error;
+
+ found:
+	atomic_inc(&key->usage);
+ error:
+	return key;
+
+} /* end __keyring_search_one() */
+
+/*****************************************************************************/
+/*
+ * find a keyring with the specified name
+ * - all named keyrings are searched
+ * - only find keyrings with search permission for the process
+ * - only find keyrings with a serial number greater than the one specified
+ */
+struct key *find_keyring_by_name(const char *name, key_serial_t bound)
+{
+	struct key *keyring;
+	int bucket;
+
+	keyring = ERR_PTR(-EINVAL);
+	if (!name)
+		goto error;
+
+	bucket = keyring_hash(name);
+
+	read_lock(&keyring_name_lock);
+
+	if (keyring_name_hash[bucket].next) {
+		/* search this hash bucket for a keyring with a matching name
+		 * that's readable and that hasn't been revoked */
+		list_for_each_entry(keyring,
+				    &keyring_name_hash[bucket],
+				    type_data.link
+				    ) {
+			if (keyring->flags & KEY_FLAG_REVOKED)
+				continue;
+
+			if (strcmp(keyring->description, name) != 0)
+				continue;
+
+			if (!key_permission(keyring, KEY_SEARCH))
+				continue;
+
+			/* found a potential candidate, but we still need to
+			 * check the serial number */
+			if (keyring->serial <= bound)
+				continue;
+
+			/* we've got a match */
+			atomic_inc(&keyring->usage);
+			read_unlock(&keyring_name_lock);
+			goto error;
+		}
+	}
+
+	read_unlock(&keyring_name_lock);
+	keyring = ERR_PTR(-ENOKEY);
+
+ error:
+	return keyring;
+
+} /* end find_keyring_by_name() */
+
+/*****************************************************************************/
+/*
+ * see if a cycle will will be created by inserting acyclic tree B in acyclic
+ * tree A at the topmost level (ie: as a direct child of A)
+ * - since we are adding B to A at the top level, checking for cycles should
+ *   just be a matter of seeing if node A is somewhere in tree B
+ */
+static int keyring_detect_cycle(struct key *A, struct key *B)
+{
+	struct {
+		struct key *subtree;
+		int kix;
+	} stack[KEYRING_SEARCH_MAX_DEPTH];
+
+	struct keyring_list *keylist;
+	struct key *subtree, *key;
+	int sp, kix, ret;
+
+	ret = -EDEADLK;
+	if (A == B)
+		goto error;
+
+	subtree = B;
+	sp = 0;
+
+	/* start processing a new keyring */
+ descend:
+	read_lock(&subtree->lock);
+	if (subtree->flags & KEY_FLAG_REVOKED)
+		goto not_this_keyring;
+
+	keylist = subtree->payload.subscriptions;
+	if (!keylist)
+		goto not_this_keyring;
+	kix = 0;
+
+ ascend:
+	/* iterate through the remaining keys in this keyring */
+	for (; kix < keylist->nkeys; kix++) {
+		key = keylist->keys[kix];
+
+		if (key == A)
+			goto cycle_detected;
+
+		/* recursively check nested keyrings */
+		if (key->type == &key_type_keyring) {
+			if (sp >= KEYRING_SEARCH_MAX_DEPTH)
+				goto too_deep;
+
+			/* stack the current position */
+			stack[sp].subtree = subtree;
+			stack[sp].kix = kix;
+			sp++;
+
+			/* begin again with the new keyring */
+			subtree = key;
+			goto descend;
+		}
+	}
+
+	/* the keyring we're looking at was disqualified or didn't contain a
+	 * matching key */
+ not_this_keyring:
+	read_unlock(&subtree->lock);
+
+	if (sp > 0) {
+		/* resume the checking of a keyring higher up in the tree */
+		sp--;
+		subtree = stack[sp].subtree;
+		keylist = subtree->payload.subscriptions;
+		kix = stack[sp].kix + 1;
+		goto ascend;
+	}
+
+	ret = 0; /* no cycles detected */
+
+ error:
+	return ret;
+
+ too_deep:
+	ret = -ELOOP;
+	goto error_unwind;
+ cycle_detected:
+	ret = -EDEADLK;
+ error_unwind:
+	read_unlock(&subtree->lock);
+
+	/* unwind the keyring stack */
+	while (sp > 0) {
+		sp--;
+		read_unlock(&stack[sp].subtree->lock);
+	}
+
+	goto error;
+
+} /* end keyring_detect_cycle() */
+
+/*****************************************************************************/
+/*
+ * link a key into to a keyring
+ * - must be called with the keyring's semaphore held
+ */
+int __key_link(struct key *keyring, struct key *key)
+{
+	struct keyring_list *klist, *nklist;
+	unsigned max;
+	size_t size;
+	int ret;
+
+	ret = -EKEYREVOKED;
+	if (keyring->flags & KEY_FLAG_REVOKED)
+		goto error;
+
+	ret = -ENOTDIR;
+	if (keyring->type != &key_type_keyring)
+		goto error;
+
+	/* serialise link/link calls to prevent parallel calls causing a
+	 * cycle when applied to two keyring in opposite orders */
+	down_write(&keyring_serialise_link_sem);
+
+	/* check that we aren't going to create a cycle adding one keyring to
+	 * another */
+	if (key->type == &key_type_keyring) {
+		ret = keyring_detect_cycle(keyring, key);
+		if (ret < 0)
+			goto error2;
+	}
+
+	/* check that we aren't going to overrun the user's quota */
+	ret = key_payload_reserve(keyring,
+				  keyring->datalen + KEYQUOTA_LINK_BYTES);
+	if (ret < 0)
+		goto error2;
+
+	klist = keyring->payload.subscriptions;
+
+	if (klist && klist->nkeys < klist->maxkeys) {
+		/* there's sufficient slack space to add directly */
+		atomic_inc(&key->usage);
+
+		write_lock(&keyring->lock);
+		klist->keys[klist->nkeys++] = key;
+		write_unlock(&keyring->lock);
+
+		ret = 0;
+	}
+	else {
+		/* grow the key list */
+		max = 4;
+		if (klist)
+			max += klist->maxkeys;
+
+		ret = -ENFILE;
+		size = sizeof(*klist) + sizeof(*key) * max;
+		if (size > PAGE_SIZE)
+			goto error3;
+
+		ret = -ENOMEM;
+		nklist = kmalloc(size, GFP_KERNEL);
+		if (!nklist)
+			goto error3;
+		nklist->maxkeys = max;
+		nklist->nkeys = 0;
+
+		if (klist) {
+			nklist->nkeys = klist->nkeys;
+			memcpy(nklist->keys,
+			       klist->keys,
+			       sizeof(struct key *) * klist->nkeys);
+		}
+
+		/* add the key into the new space */
+		atomic_inc(&key->usage);
+
+		write_lock(&keyring->lock);
+		keyring->payload.subscriptions = nklist;
+		nklist->keys[nklist->nkeys++] = key;
+		write_unlock(&keyring->lock);
+
+		/* dispose of the old keyring list */
+		kfree(klist);
+
+		ret = 0;
+	}
+
+ error2:
+	up_write(&keyring_serialise_link_sem);
+ error:
+	return ret;
+
+ error3:
+	/* undo the quota changes */
+	key_payload_reserve(keyring,
+			    keyring->datalen - KEYQUOTA_LINK_BYTES);
+	goto error2;
+
+} /* end __key_link() */
+
+/*****************************************************************************/
+/*
+ * link a key to a keyring
+ */
+int key_link(struct key *keyring, struct key *key)
+{
+	int ret;
+
+	key_check(keyring);
+	key_check(key);
+
+	down_write(&keyring->sem);
+	ret = __key_link(keyring, key);
+	up_write(&keyring->sem);
+
+	return ret;
+
+} /* end key_link() */
+
+EXPORT_SYMBOL(key_link);
+
+/*****************************************************************************/
+/*
+ * unlink the first link to a key from a keyring
+ */
+int key_unlink(struct key *keyring, struct key *key)
+{
+	struct keyring_list *klist;
+	int loop, ret;
+
+	key_check(keyring);
+	key_check(key);
+
+	ret = -ENOTDIR;
+	if (keyring->type != &key_type_keyring)
+		goto error;
+
+	down_write(&keyring->sem);
+
+	klist = keyring->payload.subscriptions;
+	if (klist) {
+		/* search the keyring for the key */
+		for (loop = 0; loop < klist->nkeys; loop++)
+			if (klist->keys[loop] == key)
+				goto key_is_present;
+	}
+
+	up_write(&keyring->sem);
+	ret = -ENOENT;
+	goto error;
+
+ key_is_present:
+	/* adjust the user's quota */
+	key_payload_reserve(keyring,
+			    keyring->datalen - KEYQUOTA_LINK_BYTES);
+
+	/* shuffle down the key pointers
+	 * - it might be worth shrinking the allocated memory, but that runs
+	 *   the risk of ENOMEM as we would have to copy
+	 */
+	write_lock(&keyring->lock);
+
+	klist->nkeys--;
+	if (loop < klist->nkeys)
+		memcpy(&klist->keys[loop],
+		       &klist->keys[loop + 1],
+		       (klist->nkeys - loop) * sizeof(struct key *));
+
+	write_unlock(&keyring->lock);
+
+	up_write(&keyring->sem);
+	key_put(key);
+	ret = 0;
+
+ error:
+	return ret;
+
+} /* end key_unlink() */
+
+EXPORT_SYMBOL(key_unlink);
+
+/*****************************************************************************/
+/*
+ * clear the specified process keyring
+ * - implements keyctl(KEYCTL_CLEAR)
+ */
+int keyring_clear(struct key *keyring)
+{
+	struct keyring_list *klist;
+	int loop, ret;
+
+	ret = -ENOTDIR;
+	if (keyring->type == &key_type_keyring) {
+		/* detach the pointer block with the locks held */
+		down_write(&keyring->sem);
+
+		klist = keyring->payload.subscriptions;
+		if (klist) {
+			/* adjust the quota */
+			key_payload_reserve(keyring,
+					    sizeof(struct keyring_list));
+
+			write_lock(&keyring->lock);
+			keyring->payload.subscriptions = NULL;
+			write_unlock(&keyring->lock);
+		}
+
+		up_write(&keyring->sem);
+
+		/* free the keys after the locks have been dropped */
+		if (klist) {
+			for (loop = klist->nkeys - 1; loop >= 0; loop--)
+				key_put(klist->keys[loop]);
+
+			kfree(klist);
+		}
+
+		ret = 0;
+	}
+
+	return ret;
+
+} /* end keyring_clear() */
+
+EXPORT_SYMBOL(keyring_clear);