Creation of Cybook 2416 (actually Gen4) repository

security/keys/Makefile

@@ -0,0 +1,16 @@
+#
+# Makefile for key management
+#
+
+obj-y := \
+	key.o \
+	keyring.o \
+	keyctl.o \
+	permission.o \
+	process_keys.o \
+	request_key.o \
+	request_key_auth.o \
+	user_defined.o
+
+obj-$(CONFIG_KEYS_COMPAT) += compat.o
+obj-$(CONFIG_PROC_FS) += proc.o

security/keys/compat.c

@@ -0,0 +1,86 @@
+/* compat.c: 32-bit compatibility syscall for 64-bit systems
+ *
+ * Copyright (C) 2004-5 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/syscalls.h>
+#include <linux/keyctl.h>
+#include <linux/compat.h>
+#include "internal.h"
+
+/*****************************************************************************/
+/*
+ * the key control system call, 32-bit compatibility version for 64-bit archs
+ * - this should only be called if the 64-bit arch uses weird pointers in
+ *   32-bit mode or doesn't guarantee that the top 32-bits of the argument
+ *   registers on taking a 32-bit syscall are zero
+ * - if you can, you should call sys_keyctl directly
+ */
+asmlinkage long compat_sys_keyctl(u32 option,
+				  u32 arg2, u32 arg3, u32 arg4, u32 arg5)
+{
+	switch (option) {
+	case KEYCTL_GET_KEYRING_ID:
+		return keyctl_get_keyring_ID(arg2, arg3);
+
+	case KEYCTL_JOIN_SESSION_KEYRING:
+		return keyctl_join_session_keyring(compat_ptr(arg2));
+
+	case KEYCTL_UPDATE:
+		return keyctl_update_key(arg2, compat_ptr(arg3), arg4);
+
+	case KEYCTL_REVOKE:
+		return keyctl_revoke_key(arg2);
+
+	case KEYCTL_DESCRIBE:
+		return keyctl_describe_key(arg2, compat_ptr(arg3), arg4);
+
+	case KEYCTL_CLEAR:
+		return keyctl_keyring_clear(arg2);
+
+	case KEYCTL_LINK:
+		return keyctl_keyring_link(arg2, arg3);
+
+	case KEYCTL_UNLINK:
+		return keyctl_keyring_unlink(arg2, arg3);
+
+	case KEYCTL_SEARCH:
+		return keyctl_keyring_search(arg2, compat_ptr(arg3),
+					     compat_ptr(arg4), arg5);
+
+	case KEYCTL_READ:
+		return keyctl_read_key(arg2, compat_ptr(arg3), arg4);
+
+	case KEYCTL_CHOWN:
+		return keyctl_chown_key(arg2, arg3, arg4);
+
+	case KEYCTL_SETPERM:
+		return keyctl_setperm_key(arg2, arg3);
+
+	case KEYCTL_INSTANTIATE:
+		return keyctl_instantiate_key(arg2, compat_ptr(arg3), arg4,
+					      arg5);
+
+	case KEYCTL_NEGATE:
+		return keyctl_negate_key(arg2, arg3, arg4);
+
+	case KEYCTL_SET_REQKEY_KEYRING:
+		return keyctl_set_reqkey_keyring(arg2);
+
+	case KEYCTL_SET_TIMEOUT:
+		return keyctl_set_timeout(arg2, arg3);
+
+	case KEYCTL_ASSUME_AUTHORITY:
+		return keyctl_assume_authority(arg2);
+
+	default:
+		return -EOPNOTSUPP;
+	}
+
+} /* end compat_sys_keyctl() */

security/keys/internal.h

@@ -0,0 +1,164 @@
+/* internal.h: authentication token and access key management internal defs
+ *
+ * Copyright (C) 2003-5 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.
+ */
+
+#ifndef _INTERNAL_H
+#define _INTERNAL_H
+
+#include <linux/key.h>
+#include <linux/key-ui.h>
+
+#if 0
+#define kenter(FMT, a...)	printk("==> %s("FMT")\n",__FUNCTION__ , ## a)
+#define kleave(FMT, a...)	printk("<== %s()"FMT"\n",__FUNCTION__ , ## a)
+#define kdebug(FMT, a...)	printk(FMT"\n" , ## a)
+#else
+#define kenter(FMT, a...)	do {} while(0)
+#define kleave(FMT, a...)	do {} while(0)
+#define kdebug(FMT, a...)	do {} while(0)
+#endif
+
+extern struct key_type key_type_user;
+
+/*****************************************************************************/
+/*
+ * keep track of keys for a user
+ * - this needs to be separate to user_struct to avoid a refcount-loop
+ *   (user_struct pins some keyrings which pin this struct)
+ * - this also keeps track of keys under request from userspace for this UID
+ */
+struct key_user {
+	struct rb_node		node;
+	struct list_head	consq;		/* construction queue */
+	spinlock_t		lock;
+	atomic_t		usage;		/* for accessing qnkeys & qnbytes */
+	atomic_t		nkeys;		/* number of keys */
+	atomic_t		nikeys;		/* number of instantiated keys */
+	uid_t			uid;
+	int			qnkeys;		/* number of keys allocated to this user */
+	int			qnbytes;	/* number of bytes allocated to this user */
+};
+
+#define KEYQUOTA_MAX_KEYS	100
+#define KEYQUOTA_MAX_BYTES	10000
+#define KEYQUOTA_LINK_BYTES	4		/* a link in a keyring is worth 4 bytes */
+
+extern struct rb_root	key_user_tree;
+extern spinlock_t	key_user_lock;
+extern struct key_user	root_key_user;
+
+extern struct key_user *key_user_lookup(uid_t uid);
+extern void key_user_put(struct key_user *user);
+
+
+
+extern struct rb_root key_serial_tree;
+extern spinlock_t key_serial_lock;
+extern struct semaphore key_alloc_sem;
+extern struct rw_semaphore key_construction_sem;
+extern wait_queue_head_t request_key_conswq;
+
+
+extern void keyring_publish_name(struct key *keyring);
+
+extern int __key_link(struct key *keyring, struct key *key);
+
+extern key_ref_t __keyring_search_one(key_ref_t keyring_ref,
+				      const struct key_type *type,
+				      const char *description,
+				      key_perm_t perm);
+
+extern struct key *keyring_search_instkey(struct key *keyring,
+					  key_serial_t target_id);
+
+typedef int (*key_match_func_t)(const struct key *, const void *);
+
+extern key_ref_t keyring_search_aux(key_ref_t keyring_ref,
+				    struct task_struct *tsk,
+				    struct key_type *type,
+				    const void *description,
+				    key_match_func_t match);
+
+extern key_ref_t search_process_keyrings(struct key_type *type,
+					 const void *description,
+					 key_match_func_t match,
+					 struct task_struct *tsk);
+
+extern struct key *find_keyring_by_name(const char *name, key_serial_t bound);
+
+extern int install_thread_keyring(struct task_struct *tsk);
+extern int install_process_keyring(struct task_struct *tsk);
+
+extern struct key *request_key_and_link(struct key_type *type,
+					const char *description,
+					const char *callout_info,
+					void *aux,
+					struct key *dest_keyring,
+					unsigned long flags);
+
+/*
+ * request_key authorisation
+ */
+struct request_key_auth {
+	struct key		*target_key;
+	struct task_struct	*context;
+	const char		*callout_info;
+	pid_t			pid;
+};
+
+extern struct key_type key_type_request_key_auth;
+extern struct key *request_key_auth_new(struct key *target,
+					const char *callout_info);
+
+extern struct key *key_get_instantiation_authkey(key_serial_t target_id);
+
+/*
+ * keyctl functions
+ */
+extern long keyctl_get_keyring_ID(key_serial_t, int);
+extern long keyctl_join_session_keyring(const char __user *);
+extern long keyctl_update_key(key_serial_t, const void __user *, size_t);
+extern long keyctl_revoke_key(key_serial_t);
+extern long keyctl_keyring_clear(key_serial_t);
+extern long keyctl_keyring_link(key_serial_t, key_serial_t);
+extern long keyctl_keyring_unlink(key_serial_t, key_serial_t);
+extern long keyctl_describe_key(key_serial_t, char __user *, size_t);
+extern long keyctl_keyring_search(key_serial_t, const char __user *,
+				  const char __user *, key_serial_t);
+extern long keyctl_read_key(key_serial_t, char __user *, size_t);
+extern long keyctl_chown_key(key_serial_t, uid_t, gid_t);
+extern long keyctl_setperm_key(key_serial_t, key_perm_t);
+extern long keyctl_instantiate_key(key_serial_t, const void __user *,
+				   size_t, key_serial_t);
+extern long keyctl_negate_key(key_serial_t, unsigned, key_serial_t);
+extern long keyctl_set_reqkey_keyring(int);
+extern long keyctl_set_timeout(key_serial_t, unsigned);
+extern long keyctl_assume_authority(key_serial_t);
+
+
+/*
+ * debugging key validation
+ */
+#ifdef KEY_DEBUGGING
+extern void __key_check(const struct key *);
+
+static inline void key_check(const struct key *key)
+{
+	if (key && (IS_ERR(key) || key->magic != KEY_DEBUG_MAGIC))
+		__key_check(key);
+}
+
+#else
+
+#define key_check(key) do {} while(0)
+
+#endif
+
+#endif /* _INTERNAL_H */

security/keys/keyring.c

@@ -0,0 +1,974 @@
+/* keyring.c: keyring handling
+ *
+ * Copyright (C) 2004-5 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/security.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_match(const struct key *keyring, const void *criterion);
+static void keyring_revoke(struct key *keyring);
+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,
+	.match		= keyring_match,
+	.revoke		= keyring_revoke,
+	.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
+ */
+static 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() */
+
+/*****************************************************************************/
+/*
+ * 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);
+
+		if (keyring->type_data.link.next != NULL &&
+		    !list_empty(&keyring->type_data.link))
+			list_del(&keyring->type_data.link);
+
+		write_unlock(&keyring_name_lock);
+	}
+
+	klist = rcu_dereference(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]");
+	}
+
+	rcu_read_lock();
+	klist = rcu_dereference(keyring->payload.subscriptions);
+	if (klist)
+		seq_printf(m, ": %u/%u", klist->nkeys, klist->maxkeys);
+	else
+		seq_puts(m, ": empty");
+	rcu_read_unlock();
+
+} /* end keyring_describe() */
+
+/*****************************************************************************/
+/*
+ * read a list of key IDs from the keyring's contents
+ * - the keyring's semaphore is read-locked
+ */
+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 = rcu_dereference(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,
+			  struct task_struct *ctx, unsigned long flags,
+			  struct key *dest)
+{
+	struct key *keyring;
+	int ret;
+
+	keyring = key_alloc(&key_type_keyring, description,
+			    uid, gid, ctx,
+			    (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL,
+			    flags);
+
+	if (!IS_ERR(keyring)) {
+		ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL);
+		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 rely on RCU to prevent the keyring lists from disappearing on us
+ * - we return -EAGAIN if we didn't find any matching key
+ * - we return -ENOKEY if we only found negative matching keys
+ * - we propagate the possession attribute from the keyring ref to the key ref
+ */
+key_ref_t keyring_search_aux(key_ref_t keyring_ref,
+			     struct task_struct *context,
+			     struct key_type *type,
+			     const void *description,
+			     key_match_func_t match)
+{
+	struct {
+		struct keyring_list *keylist;
+		int kix;
+	} stack[KEYRING_SEARCH_MAX_DEPTH];
+
+	struct keyring_list *keylist;
+	struct timespec now;
+	unsigned long possessed;
+	struct key *keyring, *key;
+	key_ref_t key_ref;
+	long err;
+	int sp, kix;
+
+	keyring = key_ref_to_ptr(keyring_ref);
+	possessed = is_key_possessed(keyring_ref);
+	key_check(keyring);
+
+	/* top keyring must have search permission to begin the search */
+        err = key_task_permission(keyring_ref, context, KEY_SEARCH);
+	if (err < 0) {
+		key_ref = ERR_PTR(err);
+		goto error;
+	}
+
+	key_ref = ERR_PTR(-ENOTDIR);
+	if (keyring->type != &key_type_keyring)
+		goto error;
+
+	rcu_read_lock();
+
+	now = current_kernel_time();
+	err = -EAGAIN;
+	sp = 0;
+
+	/* start processing a new keyring */
+descend:
+	if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
+		goto not_this_keyring;
+
+	keylist = rcu_dereference(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 (test_bit(KEY_FLAG_REVOKED, &key->flags))
+			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_task_permission(make_key_ref(key, possessed),
+					context, KEY_SEARCH) < 0)
+			continue;
+
+		/* we set a different error code if we find a negative key */
+		if (test_bit(KEY_FLAG_NEGATIVE, &key->flags)) {
+			err = -ENOKEY;
+			continue;
+		}
+
+		goto found;
+	}
+
+	/* search through the keyrings nested in this one */
+	kix = 0;
+ascend:
+	for (; kix < keylist->nkeys; kix++) {
+		key = keylist->keys[kix];
+		if (key->type != &key_type_keyring)
+			continue;
+
+		/* recursively search nested keyrings
+		 * - only search keyrings for which we have search permission
+		 */
+		if (sp >= KEYRING_SEARCH_MAX_DEPTH)
+			continue;
+
+		if (key_task_permission(make_key_ref(key, possessed),
+					context, KEY_SEARCH) < 0)
+			continue;
+
+		/* stack the current position */
+		stack[sp].keylist = keylist;
+		stack[sp].kix = kix;
+		sp++;
+
+		/* begin again with the new keyring */
+		keyring = key;
+		goto descend;
+	}
+
+	/* the keyring we're looking at was disqualified or didn't contain a
+	 * matching key */
+not_this_keyring:
+	if (sp > 0) {
+		/* resume the processing of a keyring higher up in the tree */
+		sp--;
+		keylist = stack[sp].keylist;
+		kix = stack[sp].kix + 1;
+		goto ascend;
+	}
+
+	key_ref = ERR_PTR(err);
+	goto error_2;
+
+	/* we found a viable match */
+found:
+	atomic_inc(&key->usage);
+	key_check(key);
+	key_ref = make_key_ref(key, possessed);
+error_2:
+	rcu_read_unlock();
+error:
+	return key_ref;
+
+} /* 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
+ */
+key_ref_t keyring_search(key_ref_t keyring,
+			 struct key_type *type,
+			 const char *description)
+{
+	if (!type->match)
+		return ERR_PTR(-ENOKEY);
+
+	return keyring_search_aux(keyring, current,
+				  type, description, type->match);
+
+} /* end keyring_search() */
+
+EXPORT_SYMBOL(keyring_search);
+
+/*****************************************************************************/
+/*
+ * search the given keyring only (no recursion)
+ * - keyring must be locked by caller
+ * - caller must guarantee that the keyring is a keyring
+ */
+key_ref_t __keyring_search_one(key_ref_t keyring_ref,
+			       const struct key_type *ktype,
+			       const char *description,
+			       key_perm_t perm)
+{
+	struct keyring_list *klist;
+	unsigned long possessed;
+	struct key *keyring, *key;
+	int loop;
+
+	keyring = key_ref_to_ptr(keyring_ref);
+	possessed = is_key_possessed(keyring_ref);
+
+	rcu_read_lock();
+
+	klist = rcu_dereference(keyring->payload.subscriptions);
+	if (klist) {
+		for (loop = 0; loop < klist->nkeys; loop++) {
+			key = klist->keys[loop];
+
+			if (key->type == ktype &&
+			    (!key->type->match ||
+			     key->type->match(key, description)) &&
+			    key_permission(make_key_ref(key, possessed),
+					   perm) == 0 &&
+			    !test_bit(KEY_FLAG_REVOKED, &key->flags)
+			    )
+				goto found;
+		}
+	}
+
+	rcu_read_unlock();
+	return ERR_PTR(-ENOKEY);
+
+ found:
+	atomic_inc(&key->usage);
+	rcu_read_unlock();
+	return make_key_ref(key, possessed);
+
+} /* 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 (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
+				continue;
+
+			if (strcmp(keyring->description, name) != 0)
+				continue;
+
+			if (key_permission(make_key_ref(keyring, 0),
+					   KEY_SEARCH) < 0)
+				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 keyring_list *keylist;
+		int kix;
+	} stack[KEYRING_SEARCH_MAX_DEPTH];
+
+	struct keyring_list *keylist;
+	struct key *subtree, *key;
+	int sp, kix, ret;
+
+	rcu_read_lock();
+
+	ret = -EDEADLK;
+	if (A == B)
+		goto cycle_detected;
+
+	subtree = B;
+	sp = 0;
+
+	/* start processing a new keyring */
+ descend:
+	if (test_bit(KEY_FLAG_REVOKED, &subtree->flags))
+		goto not_this_keyring;
+
+	keylist = rcu_dereference(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].keylist = keylist;
+			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:
+	if (sp > 0) {
+		/* resume the checking of a keyring higher up in the tree */
+		sp--;
+		keylist = stack[sp].keylist;
+		kix = stack[sp].kix + 1;
+		goto ascend;
+	}
+
+	ret = 0; /* no cycles detected */
+
+ error:
+	rcu_read_unlock();
+	return ret;
+
+ too_deep:
+	ret = -ELOOP;
+	goto error;
+
+ cycle_detected:
+	ret = -EDEADLK;
+	goto error;
+
+} /* end keyring_detect_cycle() */
+
+/*****************************************************************************/
+/*
+ * dispose of a keyring list after the RCU grace period
+ */
+static void keyring_link_rcu_disposal(struct rcu_head *rcu)
+{
+	struct keyring_list *klist =
+		container_of(rcu, struct keyring_list, rcu);
+
+	kfree(klist);
+
+} /* end keyring_link_rcu_disposal() */
+
+/*****************************************************************************/
+/*
+ * dispose of a keyring list after the RCU grace period, freeing the unlinked
+ * key
+ */
+static void keyring_unlink_rcu_disposal(struct rcu_head *rcu)
+{
+	struct keyring_list *klist =
+		container_of(rcu, struct keyring_list, rcu);
+
+	key_put(klist->keys[klist->delkey]);
+	kfree(klist);
+
+} /* end keyring_unlink_rcu_disposal() */
+
+/*****************************************************************************/
+/*
+ * link a key into to a keyring
+ * - must be called with the keyring's semaphore write-locked
+ * - discard already extant link to matching key if there is one
+ */
+int __key_link(struct key *keyring, struct key *key)
+{
+	struct keyring_list *klist, *nklist;
+	unsigned max;
+	size_t size;
+	int loop, ret;
+
+	ret = -EKEYREVOKED;
+	if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
+		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;
+	}
+
+	/* see if there's a matching key we can displace */
+	klist = keyring->payload.subscriptions;
+
+	if (klist && klist->nkeys > 0) {
+		struct key_type *type = key->type;
+
+		for (loop = klist->nkeys - 1; loop >= 0; loop--) {
+			if (klist->keys[loop]->type == type &&
+			    strcmp(klist->keys[loop]->description,
+				   key->description) == 0
+			    ) {
+				/* found a match - replace with new key */
+				size = sizeof(struct key *) * klist->maxkeys;
+				size += sizeof(*klist);
+				BUG_ON(size > PAGE_SIZE);
+
+				ret = -ENOMEM;
+				nklist = kmemdup(klist, size, GFP_KERNEL);
+				if (!nklist)
+					goto error2;
+
+				/* replace matched key */
+				atomic_inc(&key->usage);
+				nklist->keys[loop] = key;
+
+				rcu_assign_pointer(
+					keyring->payload.subscriptions,
+					nklist);
+
+				/* dispose of the old keyring list and the
+				 * displaced key */
+				klist->delkey = loop;
+				call_rcu(&klist->rcu,
+					 keyring_unlink_rcu_disposal);
+
+				goto done;
+			}
+		}
+	}
+
+	/* 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);
+
+		klist->keys[klist->nkeys] = key;
+		smp_wmb();
+		klist->nkeys++;
+		smp_wmb();
+	}
+	else {
+		/* grow the key list */
+		max = 4;
+		if (klist)
+			max += klist->maxkeys;
+
+		ret = -ENFILE;
+		if (max > 65535)
+			goto error3;
+		size = sizeof(*klist) + sizeof(struct 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);
+		nklist->keys[nklist->nkeys++] = key;
+
+		rcu_assign_pointer(keyring->payload.subscriptions, nklist);
+
+		/* dispose of the old keyring list */
+		if (klist)
+			call_rcu(&klist->rcu, keyring_link_rcu_disposal);
+	}
+
+done:
+	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, *nklist;
+	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:
+	/* we need to copy the key list for RCU purposes */
+	nklist = kmalloc(sizeof(*klist) +
+			 sizeof(struct key *) * klist->maxkeys,
+			 GFP_KERNEL);
+	if (!nklist)
+		goto nomem;
+	nklist->maxkeys = klist->maxkeys;
+	nklist->nkeys = klist->nkeys - 1;
+
+	if (loop > 0)
+		memcpy(&nklist->keys[0],
+		       &klist->keys[0],
+		       loop * sizeof(struct key *));
+
+	if (loop < nklist->nkeys)
+		memcpy(&nklist->keys[loop],
+		       &klist->keys[loop + 1],
+		       (nklist->nkeys - loop) * sizeof(struct key *));
+
+	/* adjust the user's quota */
+	key_payload_reserve(keyring,
+			    keyring->datalen - KEYQUOTA_LINK_BYTES);
+
+	rcu_assign_pointer(keyring->payload.subscriptions, nklist);
+
+	up_write(&keyring->sem);
+
+	/* schedule for later cleanup */
+	klist->delkey = loop;
+	call_rcu(&klist->rcu, keyring_unlink_rcu_disposal);
+
+	ret = 0;
+
+error:
+	return ret;
+nomem:
+	ret = -ENOMEM;
+	up_write(&keyring->sem);
+	goto error;
+
+} /* end key_unlink() */
+
+EXPORT_SYMBOL(key_unlink);
+
+/*****************************************************************************/
+/*
+ * dispose of a keyring list after the RCU grace period, releasing the keys it
+ * links to
+ */
+static void keyring_clear_rcu_disposal(struct rcu_head *rcu)
+{
+	struct keyring_list *klist;
+	int loop;
+
+	klist = container_of(rcu, struct keyring_list, rcu);
+
+	for (loop = klist->nkeys - 1; loop >= 0; loop--)
+		key_put(klist->keys[loop]);
+
+	kfree(klist);
+
+} /* end keyring_clear_rcu_disposal() */
+
+/*****************************************************************************/
+/*
+ * clear the specified process keyring
+ * - implements keyctl(KEYCTL_CLEAR)
+ */
+int keyring_clear(struct key *keyring)
+{
+	struct keyring_list *klist;
+	int 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));
+
+			rcu_assign_pointer(keyring->payload.subscriptions,
+					   NULL);
+		}
+
+		up_write(&keyring->sem);
+
+		/* free the keys after the locks have been dropped */
+		if (klist)
+			call_rcu(&klist->rcu, keyring_clear_rcu_disposal);
+
+		ret = 0;
+	}
+
+	return ret;
+
+} /* end keyring_clear() */
+
+EXPORT_SYMBOL(keyring_clear);
+
+/*****************************************************************************/
+/*
+ * dispose of the links from a revoked keyring
+ * - called with the key sem write-locked
+ */
+static void keyring_revoke(struct key *keyring)
+{
+	struct keyring_list *klist = keyring->payload.subscriptions;
+
+	/* adjust the quota */
+	key_payload_reserve(keyring, 0);
+
+	if (klist) {
+		rcu_assign_pointer(keyring->payload.subscriptions, NULL);
+		call_rcu(&klist->rcu, keyring_clear_rcu_disposal);
+	}
+
+} /* end keyring_revoke() */

security/keys/permission.c

@@ -0,0 +1,107 @@
+/* permission.c: key permission determination
+ *
+ * Copyright (C) 2005 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/security.h>
+#include "internal.h"
+
+/*****************************************************************************/
+/*
+ * check to see whether permission is granted to use a key in the desired way,
+ * but permit the security modules to override
+ */
+int key_task_permission(const key_ref_t key_ref,
+			struct task_struct *context,
+			key_perm_t perm)
+{
+	struct key *key;
+	key_perm_t kperm;
+	int ret;
+
+	key = key_ref_to_ptr(key_ref);
+
+	/* use the second 8-bits of permissions for keys the caller owns */
+	if (key->uid == context->fsuid) {
+		kperm = key->perm >> 16;
+		goto use_these_perms;
+	}
+
+	/* use the third 8-bits of permissions for keys the caller has a group
+	 * membership in common with */
+	if (key->gid != -1 && key->perm & KEY_GRP_ALL) {
+		if (key->gid == context->fsgid) {
+			kperm = key->perm >> 8;
+			goto use_these_perms;
+		}
+
+		task_lock(context);
+		ret = groups_search(context->group_info, key->gid);
+		task_unlock(context);
+
+		if (ret) {
+			kperm = key->perm >> 8;
+			goto use_these_perms;
+		}
+	}
+
+	/* otherwise use the least-significant 8-bits */
+	kperm = key->perm;
+
+use_these_perms:
+	/* use the top 8-bits of permissions for keys the caller possesses
+	 * - possessor permissions are additive with other permissions
+	 */
+	if (is_key_possessed(key_ref))
+		kperm |= key->perm >> 24;
+
+	kperm = kperm & perm & KEY_ALL;
+
+	if (kperm != perm)
+		return -EACCES;
+
+	/* let LSM be the final arbiter */
+	return security_key_permission(key_ref, context, perm);
+
+} /* end key_task_permission() */
+
+EXPORT_SYMBOL(key_task_permission);
+
+/*****************************************************************************/
+/*
+ * validate a key
+ */
+int key_validate(struct key *key)
+{
+	struct timespec now;
+	int ret = 0;
+
+	if (key) {
+		/* check it's still accessible */
+		ret = -EKEYREVOKED;
+		if (test_bit(KEY_FLAG_REVOKED, &key->flags) ||
+		    test_bit(KEY_FLAG_DEAD, &key->flags))
+			goto error;
+
+		/* check it hasn't expired */
+		ret = 0;
+		if (key->expiry) {
+			now = current_kernel_time();
+			if (now.tv_sec >= key->expiry)
+				ret = -EKEYEXPIRED;
+		}
+	}
+
+ error:
+	return ret;
+
+} /* end key_validate() */
+
+EXPORT_SYMBOL(key_validate);

security/keys/proc.c

@@ -0,0 +1,263 @@
+/* proc.c: proc files for key database enumeration
+ *
+ * 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/fs.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <asm/errno.h>
+#include "internal.h"
+
+#ifdef CONFIG_KEYS_DEBUG_PROC_KEYS
+static int proc_keys_open(struct inode *inode, struct file *file);
+static void *proc_keys_start(struct seq_file *p, loff_t *_pos);
+static void *proc_keys_next(struct seq_file *p, void *v, loff_t *_pos);
+static void proc_keys_stop(struct seq_file *p, void *v);
+static int proc_keys_show(struct seq_file *m, void *v);
+
+static struct seq_operations proc_keys_ops = {
+	.start	= proc_keys_start,
+	.next	= proc_keys_next,
+	.stop	= proc_keys_stop,
+	.show	= proc_keys_show,
+};
+
+static const struct file_operations proc_keys_fops = {
+	.open		= proc_keys_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= seq_release,
+};
+#endif
+
+static int proc_key_users_open(struct inode *inode, struct file *file);
+static void *proc_key_users_start(struct seq_file *p, loff_t *_pos);
+static void *proc_key_users_next(struct seq_file *p, void *v, loff_t *_pos);
+static void proc_key_users_stop(struct seq_file *p, void *v);
+static int proc_key_users_show(struct seq_file *m, void *v);
+
+static struct seq_operations proc_key_users_ops = {
+	.start	= proc_key_users_start,
+	.next	= proc_key_users_next,
+	.stop	= proc_key_users_stop,
+	.show	= proc_key_users_show,
+};
+
+static const struct file_operations proc_key_users_fops = {
+	.open		= proc_key_users_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= seq_release,
+};
+
+/*****************************************************************************/
+/*
+ * declare the /proc files
+ */
+static int __init key_proc_init(void)
+{
+	struct proc_dir_entry *p;
+
+#ifdef CONFIG_KEYS_DEBUG_PROC_KEYS
+	p = create_proc_entry("keys", 0, NULL);
+	if (!p)
+		panic("Cannot create /proc/keys\n");
+
+	p->proc_fops = &proc_keys_fops;
+#endif
+
+	p = create_proc_entry("key-users", 0, NULL);
+	if (!p)
+		panic("Cannot create /proc/key-users\n");
+
+	p->proc_fops = &proc_key_users_fops;
+
+	return 0;
+
+} /* end key_proc_init() */
+
+__initcall(key_proc_init);
+
+/*****************************************************************************/
+/*
+ * implement "/proc/keys" to provides a list of the keys on the system
+ */
+#ifdef CONFIG_KEYS_DEBUG_PROC_KEYS
+
+static int proc_keys_open(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &proc_keys_ops);
+
+}
+
+static void *proc_keys_start(struct seq_file *p, loff_t *_pos)
+{
+	struct rb_node *_p;
+	loff_t pos = *_pos;
+
+	spin_lock(&key_serial_lock);
+
+	_p = rb_first(&key_serial_tree);
+	while (pos > 0 && _p) {
+		pos--;
+		_p = rb_next(_p);
+	}
+
+	return _p;
+
+}
+
+static void *proc_keys_next(struct seq_file *p, void *v, loff_t *_pos)
+{
+	(*_pos)++;
+	return rb_next((struct rb_node *) v);
+
+}
+
+static void proc_keys_stop(struct seq_file *p, void *v)
+{
+	spin_unlock(&key_serial_lock);
+}
+
+static int proc_keys_show(struct seq_file *m, void *v)
+{
+	struct rb_node *_p = v;
+	struct key *key = rb_entry(_p, struct key, serial_node);
+	struct timespec now;
+	unsigned long timo;
+	char xbuf[12];
+	int rc;
+
+	/* check whether the current task is allowed to view the key (assuming
+	 * non-possession) */
+	rc = key_task_permission(make_key_ref(key, 0), current, KEY_VIEW);
+	if (rc < 0)
+		return 0;
+
+	now = current_kernel_time();
+
+	rcu_read_lock();
+
+	/* come up with a suitable timeout value */
+	if (key->expiry == 0) {
+		memcpy(xbuf, "perm", 5);
+	}
+	else if (now.tv_sec >= key->expiry) {
+		memcpy(xbuf, "expd", 5);
+	}
+	else {
+		timo = key->expiry - now.tv_sec;
+
+		if (timo < 60)
+			sprintf(xbuf, "%lus", timo);
+		else if (timo < 60*60)
+			sprintf(xbuf, "%lum", timo / 60);
+		else if (timo < 60*60*24)
+			sprintf(xbuf, "%luh", timo / (60*60));
+		else if (timo < 60*60*24*7)
+			sprintf(xbuf, "%lud", timo / (60*60*24));
+		else
+			sprintf(xbuf, "%luw", timo / (60*60*24*7));
+	}
+
+#define showflag(KEY, LETTER, FLAG) \
+	(test_bit(FLAG,	&(KEY)->flags) ? LETTER : '-')
+
+	seq_printf(m, "%08x %c%c%c%c%c%c %5d %4s %08x %5d %5d %-9.9s ",
+		   key->serial,
+		   showflag(key, 'I', KEY_FLAG_INSTANTIATED),
+		   showflag(key, 'R', KEY_FLAG_REVOKED),
+		   showflag(key, 'D', KEY_FLAG_DEAD),
+		   showflag(key, 'Q', KEY_FLAG_IN_QUOTA),
+		   showflag(key, 'U', KEY_FLAG_USER_CONSTRUCT),
+		   showflag(key, 'N', KEY_FLAG_NEGATIVE),
+		   atomic_read(&key->usage),
+		   xbuf,
+		   key->perm,
+		   key->uid,
+		   key->gid,
+		   key->type->name);
+
+#undef showflag
+
+	if (key->type->describe)
+		key->type->describe(key, m);
+	seq_putc(m, '\n');
+
+	rcu_read_unlock();
+
+	return 0;
+
+}
+
+#endif /* CONFIG_KEYS_DEBUG_PROC_KEYS */
+
+/*****************************************************************************/
+/*
+ * implement "/proc/key-users" to provides a list of the key users
+ */
+static int proc_key_users_open(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &proc_key_users_ops);
+
+}
+
+static void *proc_key_users_start(struct seq_file *p, loff_t *_pos)
+{
+	struct rb_node *_p;
+	loff_t pos = *_pos;
+
+	spin_lock(&key_user_lock);
+
+	_p = rb_first(&key_user_tree);
+	while (pos > 0 && _p) {
+		pos--;
+		_p = rb_next(_p);
+	}
+
+	return _p;
+
+}
+
+static void *proc_key_users_next(struct seq_file *p, void *v, loff_t *_pos)
+{
+	(*_pos)++;
+	return rb_next((struct rb_node *) v);
+
+}
+
+static void proc_key_users_stop(struct seq_file *p, void *v)
+{
+	spin_unlock(&key_user_lock);
+}
+
+static int proc_key_users_show(struct seq_file *m, void *v)
+{
+	struct rb_node *_p = v;
+	struct key_user *user = rb_entry(_p, struct key_user, node);
+
+	seq_printf(m, "%5u: %5d %d/%d %d/%d %d/%d\n",
+		   user->uid,
+		   atomic_read(&user->usage),
+		   atomic_read(&user->nkeys),
+		   atomic_read(&user->nikeys),
+		   user->qnkeys,
+		   KEYQUOTA_MAX_KEYS,
+		   user->qnbytes,
+		   KEYQUOTA_MAX_BYTES
+		   );
+
+	return 0;
+
+}

security/keys/process_keys.c

@@ -0,0 +1,765 @@
+/* process_keys.c: management of a process's keyrings
+ *
+ * Copyright (C) 2004-5 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/keyctl.h>
+#include <linux/fs.h>
+#include <linux/err.h>
+#include <linux/mutex.h>
+#include <asm/uaccess.h>
+#include "internal.h"
+
+/* session keyring create vs join semaphore */
+static DEFINE_MUTEX(key_session_mutex);
+
+/* the root user's tracking struct */
+struct key_user root_key_user = {
+	.usage		= ATOMIC_INIT(3),
+	.consq		= LIST_HEAD_INIT(root_key_user.consq),
+	.lock		= __SPIN_LOCK_UNLOCKED(root_key_user.lock),
+	.nkeys		= ATOMIC_INIT(2),
+	.nikeys		= ATOMIC_INIT(2),
+	.uid		= 0,
+};
+
+/* the root user's UID keyring */
+struct key root_user_keyring = {
+	.usage		= ATOMIC_INIT(1),
+	.serial		= 2,
+	.type		= &key_type_keyring,
+	.user		= &root_key_user,
+	.sem		= __RWSEM_INITIALIZER(root_user_keyring.sem),
+	.perm		= (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL,
+	.flags		= 1 << KEY_FLAG_INSTANTIATED,
+	.description	= "_uid.0",
+#ifdef KEY_DEBUGGING
+	.magic		= KEY_DEBUG_MAGIC,
+#endif
+};
+
+/* the root user's default session keyring */
+struct key root_session_keyring = {
+	.usage		= ATOMIC_INIT(1),
+	.serial		= 1,
+	.type		= &key_type_keyring,
+	.user		= &root_key_user,
+	.sem		= __RWSEM_INITIALIZER(root_session_keyring.sem),
+	.perm		= (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL,
+	.flags		= 1 << KEY_FLAG_INSTANTIATED,
+	.description	= "_uid_ses.0",
+#ifdef KEY_DEBUGGING
+	.magic		= KEY_DEBUG_MAGIC,
+#endif
+};
+
+/*****************************************************************************/
+/*
+ * allocate the keyrings to be associated with a UID
+ */
+int alloc_uid_keyring(struct user_struct *user,
+		      struct task_struct *ctx)
+{
+	struct key *uid_keyring, *session_keyring;
+	char buf[20];
+	int ret;
+
+	/* concoct a default session keyring */
+	sprintf(buf, "_uid_ses.%u", user->uid);
+
+	session_keyring = keyring_alloc(buf, user->uid, (gid_t) -1, ctx,
+					KEY_ALLOC_IN_QUOTA, NULL);
+	if (IS_ERR(session_keyring)) {
+		ret = PTR_ERR(session_keyring);
+		goto error;
+	}
+
+	/* and a UID specific keyring, pointed to by the default session
+	 * keyring */
+	sprintf(buf, "_uid.%u", user->uid);
+
+	uid_keyring = keyring_alloc(buf, user->uid, (gid_t) -1, ctx,
+				    KEY_ALLOC_IN_QUOTA, session_keyring);
+	if (IS_ERR(uid_keyring)) {
+		key_put(session_keyring);
+		ret = PTR_ERR(uid_keyring);
+		goto error;
+	}
+
+	/* install the keyrings */
+	user->uid_keyring = uid_keyring;
+	user->session_keyring = session_keyring;
+	ret = 0;
+
+error:
+	return ret;
+
+} /* end alloc_uid_keyring() */
+
+/*****************************************************************************/
+/*
+ * deal with the UID changing
+ */
+void switch_uid_keyring(struct user_struct *new_user)
+{
+#if 0 /* do nothing for now */
+	struct key *old;
+
+	/* switch to the new user's session keyring if we were running under
+	 * root's default session keyring */
+	if (new_user->uid != 0 &&
+	    current->session_keyring == &root_session_keyring
+	    ) {
+		atomic_inc(&new_user->session_keyring->usage);
+
+		task_lock(current);
+		old = current->session_keyring;
+		current->session_keyring = new_user->session_keyring;
+		task_unlock(current);
+
+		key_put(old);
+	}
+#endif
+
+} /* end switch_uid_keyring() */
+
+/*****************************************************************************/
+/*
+ * install a fresh thread keyring, discarding the old one
+ */
+int install_thread_keyring(struct task_struct *tsk)
+{
+	struct key *keyring, *old;
+	char buf[20];
+	int ret;
+
+	sprintf(buf, "_tid.%u", tsk->pid);
+
+	keyring = keyring_alloc(buf, tsk->uid, tsk->gid, tsk,
+				KEY_ALLOC_QUOTA_OVERRUN, NULL);
+	if (IS_ERR(keyring)) {
+		ret = PTR_ERR(keyring);
+		goto error;
+	}
+
+	task_lock(tsk);
+	old = tsk->thread_keyring;
+	tsk->thread_keyring = keyring;
+	task_unlock(tsk);
+
+	ret = 0;
+
+	key_put(old);
+error:
+	return ret;
+
+} /* end install_thread_keyring() */
+
+/*****************************************************************************/
+/*
+ * make sure a process keyring is installed
+ */
+int install_process_keyring(struct task_struct *tsk)
+{
+	struct key *keyring;
+	char buf[20];
+	int ret;
+
+	might_sleep();
+
+	if (!tsk->signal->process_keyring) {
+		sprintf(buf, "_pid.%u", tsk->tgid);
+
+		keyring = keyring_alloc(buf, tsk->uid, tsk->gid, tsk,
+					KEY_ALLOC_QUOTA_OVERRUN, NULL);
+		if (IS_ERR(keyring)) {
+			ret = PTR_ERR(keyring);
+			goto error;
+		}
+
+		/* attach keyring */
+		spin_lock_irq(&tsk->sighand->siglock);
+		if (!tsk->signal->process_keyring) {
+			tsk->signal->process_keyring = keyring;
+			keyring = NULL;
+		}
+		spin_unlock_irq(&tsk->sighand->siglock);
+
+		key_put(keyring);
+	}
+
+	ret = 0;
+error:
+	return ret;
+
+} /* end install_process_keyring() */
+
+/*****************************************************************************/
+/*
+ * install a session keyring, discarding the old one
+ * - if a keyring is not supplied, an empty one is invented
+ */
+static int install_session_keyring(struct task_struct *tsk,
+				   struct key *keyring)
+{
+	unsigned long flags;
+	struct key *old;
+	char buf[20];
+
+	might_sleep();
+
+	/* create an empty session keyring */
+	if (!keyring) {
+		sprintf(buf, "_ses.%u", tsk->tgid);
+
+		flags = KEY_ALLOC_QUOTA_OVERRUN;
+		if (tsk->signal->session_keyring)
+			flags = KEY_ALLOC_IN_QUOTA;
+
+		keyring = keyring_alloc(buf, tsk->uid, tsk->gid, tsk,
+					flags, NULL);
+		if (IS_ERR(keyring))
+			return PTR_ERR(keyring);
+	}
+	else {
+		atomic_inc(&keyring->usage);
+	}
+
+	/* install the keyring */
+	spin_lock_irq(&tsk->sighand->siglock);
+	old = tsk->signal->session_keyring;
+	rcu_assign_pointer(tsk->signal->session_keyring, keyring);
+	spin_unlock_irq(&tsk->sighand->siglock);
+
+	/* we're using RCU on the pointer, but there's no point synchronising
+	 * on it if it didn't previously point to anything */
+	if (old) {
+		synchronize_rcu();
+		key_put(old);
+	}
+
+	return 0;
+
+} /* end install_session_keyring() */
+
+/*****************************************************************************/
+/*
+ * copy the keys in a thread group for fork without CLONE_THREAD
+ */
+int copy_thread_group_keys(struct task_struct *tsk)
+{
+	key_check(current->thread_group->session_keyring);
+	key_check(current->thread_group->process_keyring);
+
+	/* no process keyring yet */
+	tsk->signal->process_keyring = NULL;
+
+	/* same session keyring */
+	rcu_read_lock();
+	tsk->signal->session_keyring =
+		key_get(rcu_dereference(current->signal->session_keyring));
+	rcu_read_unlock();
+
+	return 0;
+
+} /* end copy_thread_group_keys() */
+
+/*****************************************************************************/
+/*
+ * copy the keys for fork
+ */
+int copy_keys(unsigned long clone_flags, struct task_struct *tsk)
+{
+	key_check(tsk->thread_keyring);
+	key_check(tsk->request_key_auth);
+
+	/* no thread keyring yet */
+	tsk->thread_keyring = NULL;
+
+	/* copy the request_key() authorisation for this thread */
+	key_get(tsk->request_key_auth);
+
+	return 0;
+
+} /* end copy_keys() */
+
+/*****************************************************************************/
+/*
+ * dispose of thread group keys upon thread group destruction
+ */
+void exit_thread_group_keys(struct signal_struct *tg)
+{
+	key_put(tg->session_keyring);
+	key_put(tg->process_keyring);
+
+} /* end exit_thread_group_keys() */
+
+/*****************************************************************************/
+/*
+ * dispose of per-thread keys upon thread exit
+ */
+void exit_keys(struct task_struct *tsk)
+{
+	key_put(tsk->thread_keyring);
+	key_put(tsk->request_key_auth);
+
+} /* end exit_keys() */
+
+/*****************************************************************************/
+/*
+ * deal with execve()
+ */
+int exec_keys(struct task_struct *tsk)
+{
+	struct key *old;
+
+	/* newly exec'd tasks don't get a thread keyring */
+	task_lock(tsk);
+	old = tsk->thread_keyring;
+	tsk->thread_keyring = NULL;
+	task_unlock(tsk);
+
+	key_put(old);
+
+	/* discard the process keyring from a newly exec'd task */
+	spin_lock_irq(&tsk->sighand->siglock);
+	old = tsk->signal->process_keyring;
+	tsk->signal->process_keyring = NULL;
+	spin_unlock_irq(&tsk->sighand->siglock);
+
+	key_put(old);
+
+	return 0;
+
+} /* end exec_keys() */
+
+/*****************************************************************************/
+/*
+ * deal with SUID programs
+ * - we might want to make this invent a new session keyring
+ */
+int suid_keys(struct task_struct *tsk)
+{
+	return 0;
+
+} /* end suid_keys() */
+
+/*****************************************************************************/
+/*
+ * the filesystem user ID changed
+ */
+void key_fsuid_changed(struct task_struct *tsk)
+{
+	/* update the ownership of the thread keyring */
+	if (tsk->thread_keyring) {
+		down_write(&tsk->thread_keyring->sem);
+		tsk->thread_keyring->uid = tsk->fsuid;
+		up_write(&tsk->thread_keyring->sem);
+	}
+
+} /* end key_fsuid_changed() */
+
+/*****************************************************************************/
+/*
+ * the filesystem group ID changed
+ */
+void key_fsgid_changed(struct task_struct *tsk)
+{
+	/* update the ownership of the thread keyring */
+	if (tsk->thread_keyring) {
+		down_write(&tsk->thread_keyring->sem);
+		tsk->thread_keyring->gid = tsk->fsgid;
+		up_write(&tsk->thread_keyring->sem);
+	}
+
+} /* end key_fsgid_changed() */
+
+/*****************************************************************************/
+/*
+ * search the process keyrings for the first matching key
+ * - we use the supplied match function to see if the description (or other
+ *   feature of interest) matches
+ * - we return -EAGAIN if we didn't find any matching key
+ * - we return -ENOKEY if we found only negative matching keys
+ */
+key_ref_t search_process_keyrings(struct key_type *type,
+				  const void *description,
+				  key_match_func_t match,
+				  struct task_struct *context)
+{
+	struct request_key_auth *rka;
+	key_ref_t key_ref, ret, err;
+
+	might_sleep();
+
+	/* we want to return -EAGAIN or -ENOKEY if any of the keyrings were
+	 * searchable, but we failed to find a key or we found a negative key;
+	 * otherwise we want to return a sample error (probably -EACCES) if
+	 * none of the keyrings were searchable
+	 *
+	 * in terms of priority: success > -ENOKEY > -EAGAIN > other error
+	 */
+	key_ref = NULL;
+	ret = NULL;
+	err = ERR_PTR(-EAGAIN);
+
+	/* search the thread keyring first */
+	if (context->thread_keyring) {
+		key_ref = keyring_search_aux(
+			make_key_ref(context->thread_keyring, 1),
+			context, type, description, match);
+		if (!IS_ERR(key_ref))
+			goto found;
+
+		switch (PTR_ERR(key_ref)) {
+		case -EAGAIN: /* no key */
+			if (ret)
+				break;
+		case -ENOKEY: /* negative key */
+			ret = key_ref;
+			break;
+		default:
+			err = key_ref;
+			break;
+		}
+	}
+
+	/* search the process keyring second */
+	if (context->signal->process_keyring) {
+		key_ref = keyring_search_aux(
+			make_key_ref(context->signal->process_keyring, 1),
+			context, type, description, match);
+		if (!IS_ERR(key_ref))
+			goto found;
+
+		switch (PTR_ERR(key_ref)) {
+		case -EAGAIN: /* no key */
+			if (ret)
+				break;
+		case -ENOKEY: /* negative key */
+			ret = key_ref;
+			break;
+		default:
+			err = key_ref;
+			break;
+		}
+	}
+
+	/* search the session keyring */
+	if (context->signal->session_keyring) {
+		rcu_read_lock();
+		key_ref = keyring_search_aux(
+			make_key_ref(rcu_dereference(
+					     context->signal->session_keyring),
+				     1),
+			context, type, description, match);
+		rcu_read_unlock();
+
+		if (!IS_ERR(key_ref))
+			goto found;
+
+		switch (PTR_ERR(key_ref)) {
+		case -EAGAIN: /* no key */
+			if (ret)
+				break;
+		case -ENOKEY: /* negative key */
+			ret = key_ref;
+			break;
+		default:
+			err = key_ref;
+			break;
+		}
+	}
+	/* or search the user-session keyring */
+	else {
+		key_ref = keyring_search_aux(
+			make_key_ref(context->user->session_keyring, 1),
+			context, type, description, match);
+		if (!IS_ERR(key_ref))
+			goto found;
+
+		switch (PTR_ERR(key_ref)) {
+		case -EAGAIN: /* no key */
+			if (ret)
+				break;
+		case -ENOKEY: /* negative key */
+			ret = key_ref;
+			break;
+		default:
+			err = key_ref;
+			break;
+		}
+	}
+
+	/* if this process has an instantiation authorisation key, then we also
+	 * search the keyrings of the process mentioned there
+	 * - we don't permit access to request_key auth keys via this method
+	 */
+	if (context->request_key_auth &&
+	    context == current &&
+	    type != &key_type_request_key_auth
+	    ) {
+		/* defend against the auth key being revoked */
+		down_read(&context->request_key_auth->sem);
+
+		if (key_validate(context->request_key_auth) == 0) {
+			rka = context->request_key_auth->payload.data;
+
+			key_ref = search_process_keyrings(type, description,
+							  match, rka->context);
+
+			up_read(&context->request_key_auth->sem);
+
+			if (!IS_ERR(key_ref))
+				goto found;
+
+			switch (PTR_ERR(key_ref)) {
+			case -EAGAIN: /* no key */
+				if (ret)
+					break;
+			case -ENOKEY: /* negative key */
+				ret = key_ref;
+				break;
+			default:
+				err = key_ref;
+				break;
+			}
+		} else {
+			up_read(&context->request_key_auth->sem);
+		}
+	}
+
+	/* no key - decide on the error we're going to go for */
+	key_ref = ret ? ret : err;
+
+found:
+	return key_ref;
+
+} /* end search_process_keyrings() */
+
+/*****************************************************************************/
+/*
+ * see if the key we're looking at is the target key
+ */
+static int lookup_user_key_possessed(const struct key *key, const void *target)
+{
+	return key == target;
+
+} /* end lookup_user_key_possessed() */
+
+/*****************************************************************************/
+/*
+ * lookup a key given a key ID from userspace with a given permissions mask
+ * - don't create special keyrings unless so requested
+ * - partially constructed keys aren't found unless requested
+ */
+key_ref_t lookup_user_key(struct task_struct *context, key_serial_t id,
+			  int create, int partial, key_perm_t perm)
+{
+	key_ref_t key_ref, skey_ref;
+	struct key *key;
+	int ret;
+
+	if (!context)
+		context = current;
+
+	key_ref = ERR_PTR(-ENOKEY);
+
+	switch (id) {
+	case KEY_SPEC_THREAD_KEYRING:
+		if (!context->thread_keyring) {
+			if (!create)
+				goto error;
+
+			ret = install_thread_keyring(context);
+			if (ret < 0) {
+				key = ERR_PTR(ret);
+				goto error;
+			}
+		}
+
+		key = context->thread_keyring;
+		atomic_inc(&key->usage);
+		key_ref = make_key_ref(key, 1);
+		break;
+
+	case KEY_SPEC_PROCESS_KEYRING:
+		if (!context->signal->process_keyring) {
+			if (!create)
+				goto error;
+
+			ret = install_process_keyring(context);
+			if (ret < 0) {
+				key = ERR_PTR(ret);
+				goto error;
+			}
+		}
+
+		key = context->signal->process_keyring;
+		atomic_inc(&key->usage);
+		key_ref = make_key_ref(key, 1);
+		break;
+
+	case KEY_SPEC_SESSION_KEYRING:
+		if (!context->signal->session_keyring) {
+			/* always install a session keyring upon access if one
+			 * doesn't exist yet */
+			ret = install_session_keyring(
+				context, context->user->session_keyring);
+			if (ret < 0)
+				goto error;
+		}
+
+		rcu_read_lock();
+		key = rcu_dereference(context->signal->session_keyring);
+		atomic_inc(&key->usage);
+		rcu_read_unlock();
+		key_ref = make_key_ref(key, 1);
+		break;
+
+	case KEY_SPEC_USER_KEYRING:
+		key = context->user->uid_keyring;
+		atomic_inc(&key->usage);
+		key_ref = make_key_ref(key, 1);
+		break;
+
+	case KEY_SPEC_USER_SESSION_KEYRING:
+		key = context->user->session_keyring;
+		atomic_inc(&key->usage);
+		key_ref = make_key_ref(key, 1);
+		break;
+
+	case KEY_SPEC_GROUP_KEYRING:
+		/* group keyrings are not yet supported */
+		key = ERR_PTR(-EINVAL);
+		goto error;
+
+	case KEY_SPEC_REQKEY_AUTH_KEY:
+		key = context->request_key_auth;
+		if (!key)
+			goto error;
+
+		atomic_inc(&key->usage);
+		key_ref = make_key_ref(key, 1);
+		break;
+
+	default:
+		key_ref = ERR_PTR(-EINVAL);
+		if (id < 1)
+			goto error;
+
+		key = key_lookup(id);
+		if (IS_ERR(key)) {
+			key_ref = ERR_PTR(PTR_ERR(key));
+			goto error;
+		}
+
+		key_ref = make_key_ref(key, 0);
+
+		/* check to see if we possess the key */
+		skey_ref = search_process_keyrings(key->type, key,
+						   lookup_user_key_possessed,
+						   current);
+
+		if (!IS_ERR(skey_ref)) {
+			key_put(key);
+			key_ref = skey_ref;
+		}
+
+		break;
+	}
+
+	/* check the status */
+	if (perm) {
+		ret = key_validate(key);
+		if (ret < 0)
+			goto invalid_key;
+	}
+
+	ret = -EIO;
+	if (!partial && !test_bit(KEY_FLAG_INSTANTIATED, &key->flags))
+		goto invalid_key;
+
+	/* check the permissions */
+	ret = key_task_permission(key_ref, context, perm);
+	if (ret < 0)
+		goto invalid_key;
+
+error:
+	return key_ref;
+
+invalid_key:
+	key_ref_put(key_ref);
+	key_ref = ERR_PTR(ret);
+	goto error;
+
+} /* end lookup_user_key() */
+
+/*****************************************************************************/
+/*
+ * join the named keyring as the session keyring if possible, or attempt to
+ * create a new one of that name if not
+ * - if the name is NULL, an empty anonymous keyring is installed instead
+ * - named session keyring joining is done with a semaphore held
+ */
+long join_session_keyring(const char *name)
+{
+	struct task_struct *tsk = current;
+	struct key *keyring;
+	long ret;
+
+	/* if no name is provided, install an anonymous keyring */
+	if (!name) {
+		ret = install_session_keyring(tsk, NULL);
+		if (ret < 0)
+			goto error;
+
+		rcu_read_lock();
+		ret = rcu_dereference(tsk->signal->session_keyring)->serial;
+		rcu_read_unlock();
+		goto error;
+	}
+
+	/* allow the user to join or create a named keyring */
+	mutex_lock(&key_session_mutex);
+
+	/* look for an existing keyring of this name */
+	keyring = find_keyring_by_name(name, 0);
+	if (PTR_ERR(keyring) == -ENOKEY) {
+		/* not found - try and create a new one */
+		keyring = keyring_alloc(name, tsk->uid, tsk->gid, tsk,
+					KEY_ALLOC_IN_QUOTA, NULL);
+		if (IS_ERR(keyring)) {
+			ret = PTR_ERR(keyring);
+			goto error2;
+		}
+	}
+	else if (IS_ERR(keyring)) {
+		ret = PTR_ERR(keyring);
+		goto error2;
+	}
+
+	/* we've got a keyring - now to install it */
+	ret = install_session_keyring(tsk, keyring);
+	if (ret < 0)
+		goto error2;
+
+	ret = keyring->serial;
+	key_put(keyring);
+
+error2:
+	mutex_unlock(&key_session_mutex);
+error:
+	return ret;
+
+} /* end join_session_keyring() */

security/keys/request_key.c

@@ -0,0 +1,522 @@
+/* request_key.c: request a key from userspace
+ *
+ * Copyright (C) 2004-6 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.
+ *
+ * See Documentation/keys-request-key.txt
+ */
+
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/kmod.h>
+#include <linux/err.h>
+#include <linux/keyctl.h>
+#include "internal.h"
+
+struct key_construction {
+	struct list_head	link;	/* link in construction queue */
+	struct key		*key;	/* key being constructed */
+};
+
+/* when waiting for someone else's keys, you get added to this */
+DECLARE_WAIT_QUEUE_HEAD(request_key_conswq);
+
+/*****************************************************************************/
+/*
+ * request userspace finish the construction of a key
+ * - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring>"
+ */
+static int call_sbin_request_key(struct key *key,
+				 struct key *authkey,
+				 const char *op,
+				 void *aux)
+{
+	struct task_struct *tsk = current;
+	key_serial_t prkey, sskey;
+	struct key *keyring;
+	char *argv[9], *envp[3], uid_str[12], gid_str[12];
+	char key_str[12], keyring_str[3][12];
+	char desc[20];
+	int ret, i;
+
+	kenter("{%d},{%d},%s", key->serial, authkey->serial, op);
+
+	/* allocate a new session keyring */
+	sprintf(desc, "_req.%u", key->serial);
+
+	keyring = keyring_alloc(desc, current->fsuid, current->fsgid, current,
+				KEY_ALLOC_QUOTA_OVERRUN, NULL);
+	if (IS_ERR(keyring)) {
+		ret = PTR_ERR(keyring);
+		goto error_alloc;
+	}
+
+	/* attach the auth key to the session keyring */
+	ret = __key_link(keyring, authkey);
+	if (ret < 0)
+		goto error_link;
+
+	/* record the UID and GID */
+	sprintf(uid_str, "%d", current->fsuid);
+	sprintf(gid_str, "%d", current->fsgid);
+
+	/* we say which key is under construction */
+	sprintf(key_str, "%d", key->serial);
+
+	/* we specify the process's default keyrings */
+	sprintf(keyring_str[0], "%d",
+		tsk->thread_keyring ? tsk->thread_keyring->serial : 0);
+
+	prkey = 0;
+	if (tsk->signal->process_keyring)
+		prkey = tsk->signal->process_keyring->serial;
+
+	sprintf(keyring_str[1], "%d", prkey);
+
+	if (tsk->signal->session_keyring) {
+		rcu_read_lock();
+		sskey = rcu_dereference(tsk->signal->session_keyring)->serial;
+		rcu_read_unlock();
+	}
+	else {
+		sskey = tsk->user->session_keyring->serial;
+	}
+
+	sprintf(keyring_str[2], "%d", sskey);
+
+	/* set up a minimal environment */
+	i = 0;
+	envp[i++] = "HOME=/";
+	envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
+	envp[i] = NULL;
+
+	/* set up the argument list */
+	i = 0;
+	argv[i++] = "/sbin/request-key";
+	argv[i++] = (char *) op;
+	argv[i++] = key_str;
+	argv[i++] = uid_str;
+	argv[i++] = gid_str;
+	argv[i++] = keyring_str[0];
+	argv[i++] = keyring_str[1];
+	argv[i++] = keyring_str[2];
+	argv[i] = NULL;
+
+	/* do it */
+	ret = call_usermodehelper_keys(argv[0], argv, envp, keyring, 1);
+
+error_link:
+	key_put(keyring);
+
+error_alloc:
+	kleave(" = %d", ret);
+	return ret;
+
+} /* end call_sbin_request_key() */
+
+/*****************************************************************************/
+/*
+ * call out to userspace for the key
+ * - called with the construction sem held, but the sem is dropped here
+ * - we ignore program failure and go on key status instead
+ */
+static struct key *__request_key_construction(struct key_type *type,
+					      const char *description,
+					      const char *callout_info,
+					      void *aux,
+					      unsigned long flags)
+{
+	request_key_actor_t actor;
+	struct key_construction cons;
+	struct timespec now;
+	struct key *key, *authkey;
+	int ret, negated;
+
+	kenter("%s,%s,%s,%lx", type->name, description, callout_info, flags);
+
+	/* create a key and add it to the queue */
+	key = key_alloc(type, description,
+			current->fsuid, current->fsgid, current, KEY_POS_ALL,
+			flags);
+	if (IS_ERR(key))
+		goto alloc_failed;
+
+	set_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags);
+
+	cons.key = key;
+	list_add_tail(&cons.link, &key->user->consq);
+
+	/* we drop the construction sem here on behalf of the caller */
+	up_write(&key_construction_sem);
+
+	/* allocate an authorisation key */
+	authkey = request_key_auth_new(key, callout_info);
+	if (IS_ERR(authkey)) {
+		ret = PTR_ERR(authkey);
+		authkey = NULL;
+		goto alloc_authkey_failed;
+	}
+
+	/* make the call */
+	actor = call_sbin_request_key;
+	if (type->request_key)
+		actor = type->request_key;
+	ret = actor(key, authkey, "create", aux);
+	if (ret < 0)
+		goto request_failed;
+
+	/* if the key wasn't instantiated, then we want to give an error */
+	ret = -ENOKEY;
+	if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags))
+		goto request_failed;
+
+	key_revoke(authkey);
+	key_put(authkey);
+
+	down_write(&key_construction_sem);
+	list_del(&cons.link);
+	up_write(&key_construction_sem);
+
+	/* also give an error if the key was negatively instantiated */
+check_not_negative:
+	if (test_bit(KEY_FLAG_NEGATIVE, &key->flags)) {
+		key_put(key);
+		key = ERR_PTR(-ENOKEY);
+	}
+
+out:
+	kleave(" = %p", key);
+	return key;
+
+request_failed:
+	key_revoke(authkey);
+	key_put(authkey);
+
+alloc_authkey_failed:
+	/* it wasn't instantiated
+	 * - remove from construction queue
+	 * - mark the key as dead
+	 */
+	negated = 0;
+	down_write(&key_construction_sem);
+
+	list_del(&cons.link);
+
+	/* check it didn't get instantiated between the check and the down */
+	if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
+		set_bit(KEY_FLAG_NEGATIVE, &key->flags);
+		set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
+		negated = 1;
+	}
+
+	clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags);
+
+	up_write(&key_construction_sem);
+
+	if (!negated)
+		goto check_not_negative; /* surprisingly, the key got
+					  * instantiated */
+
+	/* set the timeout and store in the session keyring if we can */
+	now = current_kernel_time();
+	key->expiry = now.tv_sec + key_negative_timeout;
+
+	if (current->signal->session_keyring) {
+		struct key *keyring;
+
+		rcu_read_lock();
+		keyring = rcu_dereference(current->signal->session_keyring);
+		atomic_inc(&keyring->usage);
+		rcu_read_unlock();
+
+		key_link(keyring, key);
+		key_put(keyring);
+	}
+
+	key_put(key);
+
+	/* notify anyone who was waiting */
+	wake_up_all(&request_key_conswq);
+
+	key = ERR_PTR(ret);
+	goto out;
+
+alloc_failed:
+	up_write(&key_construction_sem);
+	goto out;
+
+} /* end __request_key_construction() */
+
+/*****************************************************************************/
+/*
+ * call out to userspace to request the key
+ * - we check the construction queue first to see if an appropriate key is
+ *   already being constructed by userspace
+ */
+static struct key *request_key_construction(struct key_type *type,
+					    const char *description,
+					    const char *callout_info,
+					    void *aux,
+					    struct key_user *user,
+					    unsigned long flags)
+{
+	struct key_construction *pcons;
+	struct key *key, *ckey;
+
+	DECLARE_WAITQUEUE(myself, current);
+
+	kenter("%s,%s,{%d},%s,%lx",
+	       type->name, description, user->uid, callout_info, flags);
+
+	/* see if there's such a key under construction already */
+	down_write(&key_construction_sem);
+
+	list_for_each_entry(pcons, &user->consq, link) {
+		ckey = pcons->key;
+
+		if (ckey->type != type)
+			continue;
+
+		if (type->match(ckey, description))
+			goto found_key_under_construction;
+	}
+
+	/* see about getting userspace to construct the key */
+	key = __request_key_construction(type, description, callout_info, aux,
+					 flags);
+ error:
+	kleave(" = %p", key);
+	return key;
+
+	/* someone else has the same key under construction
+	 * - we want to keep an eye on their key
+	 */
+ found_key_under_construction:
+	atomic_inc(&ckey->usage);
+	up_write(&key_construction_sem);
+
+	/* wait for the key to be completed one way or another */
+	add_wait_queue(&request_key_conswq, &myself);
+
+	for (;;) {
+		set_current_state(TASK_INTERRUPTIBLE);
+		if (!test_bit(KEY_FLAG_USER_CONSTRUCT, &ckey->flags))
+			break;
+		if (signal_pending(current))
+			break;
+		schedule();
+	}
+
+	set_current_state(TASK_RUNNING);
+	remove_wait_queue(&request_key_conswq, &myself);
+
+	/* we'll need to search this process's keyrings to see if the key is
+	 * now there since we can't automatically assume it's also available
+	 * there */
+	key_put(ckey);
+	ckey = NULL;
+
+	key = NULL; /* request a retry */
+	goto error;
+
+} /* end request_key_construction() */
+
+/*****************************************************************************/
+/*
+ * link a freshly minted key to an appropriate destination keyring
+ */
+static void request_key_link(struct key *key, struct key *dest_keyring)
+{
+	struct task_struct *tsk = current;
+	struct key *drop = NULL;
+
+	kenter("{%d},%p", key->serial, dest_keyring);
+
+	/* find the appropriate keyring */
+	if (!dest_keyring) {
+		switch (tsk->jit_keyring) {
+		case KEY_REQKEY_DEFL_DEFAULT:
+		case KEY_REQKEY_DEFL_THREAD_KEYRING:
+			dest_keyring = tsk->thread_keyring;
+			if (dest_keyring)
+				break;
+
+		case KEY_REQKEY_DEFL_PROCESS_KEYRING:
+			dest_keyring = tsk->signal->process_keyring;
+			if (dest_keyring)
+				break;
+
+		case KEY_REQKEY_DEFL_SESSION_KEYRING:
+			rcu_read_lock();
+			dest_keyring = key_get(
+				rcu_dereference(tsk->signal->session_keyring));
+			rcu_read_unlock();
+			drop = dest_keyring;
+
+			if (dest_keyring)
+				break;
+
+		case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
+			dest_keyring = current->user->session_keyring;
+			break;
+
+		case KEY_REQKEY_DEFL_USER_KEYRING:
+			dest_keyring = current->user->uid_keyring;
+			break;
+
+		case KEY_REQKEY_DEFL_GROUP_KEYRING:
+		default:
+			BUG();
+		}
+	}
+
+	/* and attach the key to it */
+	key_link(dest_keyring, key);
+
+	key_put(drop);
+
+	kleave("");
+
+} /* end request_key_link() */
+
+/*****************************************************************************/
+/*
+ * request a key
+ * - search the process's keyrings
+ * - check the list of keys being created or updated
+ * - call out to userspace for a key if supplementary info was provided
+ * - cache the key in an appropriate keyring
+ */
+struct key *request_key_and_link(struct key_type *type,
+				 const char *description,
+				 const char *callout_info,
+				 void *aux,
+				 struct key *dest_keyring,
+				 unsigned long flags)
+{
+	struct key_user *user;
+	struct key *key;
+	key_ref_t key_ref;
+
+	kenter("%s,%s,%s,%p,%p,%lx",
+	       type->name, description, callout_info, aux,
+	       dest_keyring, flags);
+
+	/* search all the process keyrings for a key */
+	key_ref = search_process_keyrings(type, description, type->match,
+					  current);
+
+	kdebug("search 1: %p", key_ref);
+
+	if (!IS_ERR(key_ref)) {
+		key = key_ref_to_ptr(key_ref);
+	}
+	else if (PTR_ERR(key_ref) != -EAGAIN) {
+		key = ERR_PTR(PTR_ERR(key_ref));
+	}
+	else  {
+		/* the search failed, but the keyrings were searchable, so we
+		 * should consult userspace if we can */
+		key = ERR_PTR(-ENOKEY);
+		if (!callout_info)
+			goto error;
+
+		/* - get hold of the user's construction queue */
+		user = key_user_lookup(current->fsuid);
+		if (!user)
+			goto nomem;
+
+		for (;;) {
+			if (signal_pending(current))
+				goto interrupted;
+
+			/* ask userspace (returns NULL if it waited on a key
+			 * being constructed) */
+			key = request_key_construction(type, description,
+						       callout_info, aux,
+						       user, flags);
+			if (key)
+				break;
+
+			/* someone else made the key we want, so we need to
+			 * search again as it might now be available to us */
+			key_ref = search_process_keyrings(type, description,
+							  type->match,
+							  current);
+
+			kdebug("search 2: %p", key_ref);
+
+			if (!IS_ERR(key_ref)) {
+				key = key_ref_to_ptr(key_ref);
+				break;
+			}
+
+			if (PTR_ERR(key_ref) != -EAGAIN) {
+				key = ERR_PTR(PTR_ERR(key_ref));
+				break;
+			}
+		}
+
+		key_user_put(user);
+
+		/* link the new key into the appropriate keyring */
+		if (!IS_ERR(key))
+			request_key_link(key, dest_keyring);
+	}
+
+error:
+	kleave(" = %p", key);
+	return key;
+
+nomem:
+	key = ERR_PTR(-ENOMEM);
+	goto error;
+
+interrupted:
+	key_user_put(user);
+	key = ERR_PTR(-EINTR);
+	goto error;
+
+} /* end request_key_and_link() */
+
+/*****************************************************************************/
+/*
+ * request a key
+ * - search the process's keyrings
+ * - check the list of keys being created or updated
+ * - call out to userspace for a key if supplementary info was provided
+ */
+struct key *request_key(struct key_type *type,
+			const char *description,
+			const char *callout_info)
+{
+	return request_key_and_link(type, description, callout_info, NULL,
+				    NULL, KEY_ALLOC_IN_QUOTA);
+
+} /* end request_key() */
+
+EXPORT_SYMBOL(request_key);
+
+/*****************************************************************************/
+/*
+ * request a key with auxiliary data for the upcaller
+ * - search the process's keyrings
+ * - check the list of keys being created or updated
+ * - call out to userspace for a key if supplementary info was provided
+ */
+struct key *request_key_with_auxdata(struct key_type *type,
+				     const char *description,
+				     const char *callout_info,
+				     void *aux)
+{
+	return request_key_and_link(type, description, callout_info, aux,
+				    NULL, KEY_ALLOC_IN_QUOTA);
+
+} /* end request_key_with_auxdata() */
+
+EXPORT_SYMBOL(request_key_with_auxdata);

security/keys/request_key_auth.c

@@ -0,0 +1,268 @@
+/* request_key_auth.c: request key authorisation controlling key def
+ *
+ * Copyright (C) 2005 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.
+ *
+ * See Documentation/keys-request-key.txt
+ */
+
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/err.h>
+#include <linux/seq_file.h>
+#include <asm/uaccess.h>
+#include "internal.h"
+
+static int request_key_auth_instantiate(struct key *, const void *, size_t);
+static void request_key_auth_describe(const struct key *, struct seq_file *);
+static void request_key_auth_revoke(struct key *);
+static void request_key_auth_destroy(struct key *);
+static long request_key_auth_read(const struct key *, char __user *, size_t);
+
+/*
+ * the request-key authorisation key type definition
+ */
+struct key_type key_type_request_key_auth = {
+	.name		= ".request_key_auth",
+	.def_datalen	= sizeof(struct request_key_auth),
+	.instantiate	= request_key_auth_instantiate,
+	.describe	= request_key_auth_describe,
+	.revoke		= request_key_auth_revoke,
+	.destroy	= request_key_auth_destroy,
+	.read		= request_key_auth_read,
+};
+
+/*****************************************************************************/
+/*
+ * instantiate a request-key authorisation key
+ */
+static int request_key_auth_instantiate(struct key *key,
+					const void *data,
+					size_t datalen)
+{
+	key->payload.data = (struct request_key_auth *) data;
+	return 0;
+
+} /* end request_key_auth_instantiate() */
+
+/*****************************************************************************/
+/*
+ * reading a request-key authorisation key retrieves the callout information
+ */
+static void request_key_auth_describe(const struct key *key,
+				      struct seq_file *m)
+{
+	struct request_key_auth *rka = key->payload.data;
+
+	seq_puts(m, "key:");
+	seq_puts(m, key->description);
+	seq_printf(m, " pid:%d ci:%zu", rka->pid, strlen(rka->callout_info));
+
+} /* end request_key_auth_describe() */
+
+/*****************************************************************************/
+/*
+ * read the callout_info data
+ * - the key's semaphore is read-locked
+ */
+static long request_key_auth_read(const struct key *key,
+				  char __user *buffer, size_t buflen)
+{
+	struct request_key_auth *rka = key->payload.data;
+	size_t datalen;
+	long ret;
+
+	datalen = strlen(rka->callout_info);
+	ret = datalen;
+
+	/* we can return the data as is */
+	if (buffer && buflen > 0) {
+		if (buflen > datalen)
+			buflen = datalen;
+
+		if (copy_to_user(buffer, rka->callout_info, buflen) != 0)
+			ret = -EFAULT;
+	}
+
+	return ret;
+
+} /* end request_key_auth_read() */
+
+/*****************************************************************************/
+/*
+ * handle revocation of an authorisation token key
+ * - called with the key sem write-locked
+ */
+static void request_key_auth_revoke(struct key *key)
+{
+	struct request_key_auth *rka = key->payload.data;
+
+	kenter("{%d}", key->serial);
+
+	if (rka->context) {
+		put_task_struct(rka->context);
+		rka->context = NULL;
+	}
+
+} /* end request_key_auth_revoke() */
+
+/*****************************************************************************/
+/*
+ * destroy an instantiation authorisation token key
+ */
+static void request_key_auth_destroy(struct key *key)
+{
+	struct request_key_auth *rka = key->payload.data;
+
+	kenter("{%d}", key->serial);
+
+	if (rka->context) {
+		put_task_struct(rka->context);
+		rka->context = NULL;
+	}
+
+	key_put(rka->target_key);
+	kfree(rka);
+
+} /* end request_key_auth_destroy() */
+
+/*****************************************************************************/
+/*
+ * create an authorisation token for /sbin/request-key or whoever to gain
+ * access to the caller's security data
+ */
+struct key *request_key_auth_new(struct key *target, const char *callout_info)
+{
+	struct request_key_auth *rka, *irka;
+	struct key *authkey = NULL;
+	char desc[20];
+	int ret;
+
+	kenter("%d,", target->serial);
+
+	/* allocate a auth record */
+	rka = kmalloc(sizeof(*rka), GFP_KERNEL);
+	if (!rka) {
+		kleave(" = -ENOMEM");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	/* see if the calling process is already servicing the key request of
+	 * another process */
+	if (current->request_key_auth) {
+		/* it is - use that instantiation context here too */
+		down_read(&current->request_key_auth->sem);
+
+		/* if the auth key has been revoked, then the key we're
+		 * servicing is already instantiated */
+		if (test_bit(KEY_FLAG_REVOKED,
+			     &current->request_key_auth->flags))
+			goto auth_key_revoked;
+
+		irka = current->request_key_auth->payload.data;
+		rka->context = irka->context;
+		rka->pid = irka->pid;
+		get_task_struct(rka->context);
+
+		up_read(&current->request_key_auth->sem);
+	}
+	else {
+		/* it isn't - use this process as the context */
+		rka->context = current;
+		rka->pid = current->pid;
+		get_task_struct(rka->context);
+	}
+
+	rka->target_key = key_get(target);
+	rka->callout_info = callout_info;
+
+	/* allocate the auth key */
+	sprintf(desc, "%x", target->serial);
+
+	authkey = key_alloc(&key_type_request_key_auth, desc,
+			    current->fsuid, current->fsgid, current,
+			    KEY_POS_VIEW | KEY_POS_READ | KEY_POS_SEARCH |
+			    KEY_USR_VIEW, KEY_ALLOC_NOT_IN_QUOTA);
+	if (IS_ERR(authkey)) {
+		ret = PTR_ERR(authkey);
+		goto error_alloc;
+	}
+
+	/* construct and attach to the keyring */
+	ret = key_instantiate_and_link(authkey, rka, 0, NULL, NULL);
+	if (ret < 0)
+		goto error_inst;
+
+	kleave(" = {%d}", authkey->serial);
+	return authkey;
+
+auth_key_revoked:
+	up_read(&current->request_key_auth->sem);
+	kfree(rka);
+	kleave("= -EKEYREVOKED");
+	return ERR_PTR(-EKEYREVOKED);
+
+error_inst:
+	key_revoke(authkey);
+	key_put(authkey);
+error_alloc:
+	key_put(rka->target_key);
+	kfree(rka);
+	kleave("= %d", ret);
+	return ERR_PTR(ret);
+
+} /* end request_key_auth_new() */
+
+/*****************************************************************************/
+/*
+ * see if an authorisation key is associated with a particular key
+ */
+static int key_get_instantiation_authkey_match(const struct key *key,
+					       const void *_id)
+{
+	struct request_key_auth *rka = key->payload.data;
+	key_serial_t id = (key_serial_t)(unsigned long) _id;
+
+	return rka->target_key->serial == id;
+
+} /* end key_get_instantiation_authkey_match() */
+
+/*****************************************************************************/
+/*
+ * get the authorisation key for instantiation of a specific key if attached to
+ * the current process's keyrings
+ * - this key is inserted into a keyring and that is set as /sbin/request-key's
+ *   session keyring
+ * - a target_id of zero specifies any valid token
+ */
+struct key *key_get_instantiation_authkey(key_serial_t target_id)
+{
+	struct key *authkey;
+	key_ref_t authkey_ref;
+
+	authkey_ref = search_process_keyrings(
+		&key_type_request_key_auth,
+		(void *) (unsigned long) target_id,
+		key_get_instantiation_authkey_match,
+		current);
+
+	if (IS_ERR(authkey_ref)) {
+		authkey = ERR_PTR(PTR_ERR(authkey_ref));
+		goto error;
+	}
+
+	authkey = key_ref_to_ptr(authkey_ref);
+	if (test_bit(KEY_FLAG_REVOKED, &authkey->flags)) {
+		key_put(authkey);
+		authkey = ERR_PTR(-EKEYREVOKED);
+	}
+
+error:
+	return authkey;
+
+} /* end key_get_instantiation_authkey() */

security/keys/user_defined.c

@@ -0,0 +1,218 @@
+/* user_defined.c: user defined key type
+ *
+ * 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/slab.h>
+#include <linux/seq_file.h>
+#include <linux/err.h>
+#include <keys/user-type.h>
+#include <asm/uaccess.h>
+#include "internal.h"
+
+/*
+ * user defined keys take an arbitrary string as the description and an
+ * arbitrary blob of data as the payload
+ */
+struct key_type key_type_user = {
+	.name		= "user",
+	.instantiate	= user_instantiate,
+	.update		= user_update,
+	.match		= user_match,
+	.revoke		= user_revoke,
+	.destroy	= user_destroy,
+	.describe	= user_describe,
+	.read		= user_read,
+};
+
+EXPORT_SYMBOL_GPL(key_type_user);
+
+/*****************************************************************************/
+/*
+ * instantiate a user defined key
+ */
+int user_instantiate(struct key *key, const void *data, size_t datalen)
+{
+	struct user_key_payload *upayload;
+	int ret;
+
+	ret = -EINVAL;
+	if (datalen <= 0 || datalen > 32767 || !data)
+		goto error;
+
+	ret = key_payload_reserve(key, datalen);
+	if (ret < 0)
+		goto error;
+
+	ret = -ENOMEM;
+	upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL);
+	if (!upayload)
+		goto error;
+
+	/* attach the data */
+	upayload->datalen = datalen;
+	memcpy(upayload->data, data, datalen);
+	rcu_assign_pointer(key->payload.data, upayload);
+	ret = 0;
+
+error:
+	return ret;
+
+} /* end user_instantiate() */
+
+EXPORT_SYMBOL_GPL(user_instantiate);
+
+/*****************************************************************************/
+/*
+ * dispose of the old data from an updated user defined key
+ */
+static void user_update_rcu_disposal(struct rcu_head *rcu)
+{
+	struct user_key_payload *upayload;
+
+	upayload = container_of(rcu, struct user_key_payload, rcu);
+
+	kfree(upayload);
+
+} /* end user_update_rcu_disposal() */
+
+/*****************************************************************************/
+/*
+ * update a user defined key
+ * - the key's semaphore is write-locked
+ */
+int user_update(struct key *key, const void *data, size_t datalen)
+{
+	struct user_key_payload *upayload, *zap;
+	int ret;
+
+	ret = -EINVAL;
+	if (datalen <= 0 || datalen > 32767 || !data)
+		goto error;
+
+	/* construct a replacement payload */
+	ret = -ENOMEM;
+	upayload = kmalloc(sizeof(*upayload) + datalen, GFP_KERNEL);
+	if (!upayload)
+		goto error;
+
+	upayload->datalen = datalen;
+	memcpy(upayload->data, data, datalen);
+
+	/* check the quota and attach the new data */
+	zap = upayload;
+
+	ret = key_payload_reserve(key, datalen);
+
+	if (ret == 0) {
+		/* attach the new data, displacing the old */
+		zap = key->payload.data;
+		rcu_assign_pointer(key->payload.data, upayload);
+		key->expiry = 0;
+	}
+
+	call_rcu(&zap->rcu, user_update_rcu_disposal);
+
+error:
+	return ret;
+
+} /* end user_update() */
+
+EXPORT_SYMBOL_GPL(user_update);
+
+/*****************************************************************************/
+/*
+ * match users on their name
+ */
+int user_match(const struct key *key, const void *description)
+{
+	return strcmp(key->description, description) == 0;
+
+} /* end user_match() */
+
+EXPORT_SYMBOL_GPL(user_match);
+
+/*****************************************************************************/
+/*
+ * dispose of the links from a revoked keyring
+ * - called with the key sem write-locked
+ */
+void user_revoke(struct key *key)
+{
+	struct user_key_payload *upayload = key->payload.data;
+
+	/* clear the quota */
+	key_payload_reserve(key, 0);
+
+	if (upayload) {
+		rcu_assign_pointer(key->payload.data, NULL);
+		call_rcu(&upayload->rcu, user_update_rcu_disposal);
+	}
+
+} /* end user_revoke() */
+
+EXPORT_SYMBOL(user_revoke);
+
+/*****************************************************************************/
+/*
+ * dispose of the data dangling from the corpse of a user key
+ */
+void user_destroy(struct key *key)
+{
+	struct user_key_payload *upayload = key->payload.data;
+
+	kfree(upayload);
+
+} /* end user_destroy() */
+
+EXPORT_SYMBOL_GPL(user_destroy);
+
+/*****************************************************************************/
+/*
+ * describe the user key
+ */
+void user_describe(const struct key *key, struct seq_file *m)
+{
+	seq_puts(m, key->description);
+
+	seq_printf(m, ": %u", key->datalen);
+
+} /* end user_describe() */
+
+EXPORT_SYMBOL_GPL(user_describe);
+
+/*****************************************************************************/
+/*
+ * read the key data
+ * - the key's semaphore is read-locked
+ */
+long user_read(const struct key *key, char __user *buffer, size_t buflen)
+{
+	struct user_key_payload *upayload;
+	long ret;
+
+	upayload = rcu_dereference(key->payload.data);
+	ret = upayload->datalen;
+
+	/* we can return the data as is */
+	if (buffer && buflen > 0) {
+		if (buflen > upayload->datalen)
+			buflen = upayload->datalen;
+
+		if (copy_to_user(buffer, upayload->data, buflen) != 0)
+			ret = -EFAULT;
+	}
+
+	return ret;
+
+} /* end user_read() */
+
+EXPORT_SYMBOL_GPL(user_read);