[PATCH] implement in-kernel keys & keyring management

The feature set the patch includes:

 - Key attributes:
   - Key type
   - Description (by which a key of a particular type can be selected)
   - Payload
   - UID, GID and permissions mask
   - Expiry time
 - Keyrings (just a type of key that holds links to other keys)
 - User-defined keys
 - Key revokation
 - Access controls
 - Per user key-count and key-memory consumption quota
 - Three std keyrings per task: per-thread, per-process, session
 - Two std keyrings per user: per-user and default-user-session
 - prctl() functions for key and keyring creation and management
 - Kernel interfaces for filesystem, blockdev, net stack access
 - JIT key creation by usermode helper

There are also two utility programs available:

 (*) http://people.redhat.com/~dhowells/keys/keyctl.c

     A comprehensive key management tool, permitting all the interfaces
     available to userspace to be exercised.

 (*) http://people.redhat.com/~dhowells/keys/request-key

     An example shell script (to be installed in /sbin) for instantiating a
     key.

Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

6 files changed, 448 insertions, 4 deletions

diff --git a/include/linux/key-ui.h b/include/linux/key-ui.h
new file mode 100644
index 000000000000..60cc7b762e78
--- /dev/null
+++ b/include/linux/key-ui.h
@@ -0,0 +1,97 @@
+/* key-ui.h: key userspace interface stuff for use by keyfs
+ *
+ * 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.
+ */
+
+#ifndef _LINUX_KEY_UI_H
+#define _LINUX_KEY_UI_H
+
+#include <linux/key.h>
+
+/* the key tree */
+extern struct rb_root key_serial_tree;
+extern spinlock_t key_serial_lock;
+
+/* required permissions */
+#define	KEY_VIEW	0x01	/* require permission to view attributes */
+#define	KEY_READ	0x02	/* require permission to read content */
+#define	KEY_WRITE	0x04	/* require permission to update / modify */
+#define	KEY_SEARCH	0x08	/* require permission to search (keyring) or find (key) */
+#define	KEY_LINK	0x10	/* require permission to link */
+#define	KEY_ALL		0x1f	/* all the above permissions */
+
+/*
+ * the keyring payload contains a list of the keys to which the keyring is
+ * subscribed
+ */
+struct keyring_list {
+	unsigned	maxkeys;	/* max keys this list can hold */
+	unsigned	nkeys;		/* number of keys currently held */
+	struct key	*keys[0];
+};
+
+
+/*
+ * check to see whether permission is granted to use a key in the desired way
+ */
+static inline int key_permission(const struct key *key, key_perm_t perm)
+{
+	key_perm_t kperm;
+
+	if (key->uid == current->fsuid)
+		kperm = key->perm >> 16;
+	else if (key->gid != -1 &&
+		 key->perm & KEY_GRP_ALL &&
+		 in_group_p(key->gid)
+		 )
+		kperm = key->perm >> 8;
+	else
+		kperm = key->perm;
+
+	kperm = kperm & perm & KEY_ALL;
+
+	return kperm == perm;
+}
+
+/*
+ * check to see whether permission is granted to use a key in at least one of
+ * the desired ways
+ */
+static inline int key_any_permission(const struct key *key, key_perm_t perm)
+{
+	key_perm_t kperm;
+
+	if (key->uid == current->fsuid)
+		kperm = key->perm >> 16;
+	else if (key->gid != -1 &&
+		 key->perm & KEY_GRP_ALL &&
+		 in_group_p(key->gid)
+		 )
+		kperm = key->perm >> 8;
+	else
+		kperm = key->perm;
+
+	kperm = kperm & perm & KEY_ALL;
+
+	return kperm != 0;
+}
+
+
+extern struct key *lookup_user_key(key_serial_t id, int create, int part,
+				   key_perm_t perm);
+
+extern long join_session_keyring(const char *name);
+
+extern struct key_type *key_type_lookup(const char *type);
+extern void key_type_put(struct key_type *ktype);
+
+#define key_negative_timeout	60	/* default timeout on a negative key's existence */
+
+
+#endif /* _LINUX_KEY_UI_H */
diff --git a/include/linux/key.h b/include/linux/key.h
new file mode 100644
index 000000000000..e914be777c4a
--- /dev/null
+++ b/include/linux/key.h
@@ -0,0 +1,284 @@
+/* key.h: authentication token and access key management
+ *
+ * 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.
+ *
+ *
+ * See Documentation/keys.txt for information on keys/keyrings.
+ */
+
+#ifndef _LINUX_KEY_H
+#define _LINUX_KEY_H
+
+#include <linux/types.h>
+#include <linux/list.h>
+#include <linux/rbtree.h>
+#include <linux/spinlock.h>
+#include <asm/atomic.h>
+
+#ifdef __KERNEL__
+
+/* key handle serial number */
+typedef int32_t key_serial_t;
+
+/* key handle permissions mask */
+typedef uint32_t key_perm_t;
+
+struct key;
+
+#ifdef CONFIG_KEYS
+
+#undef KEY_DEBUGGING
+
+#define KEY_USR_VIEW	0x00010000	/* user can view a key's attributes */
+#define KEY_USR_READ	0x00020000	/* user can read key payload / view keyring */
+#define KEY_USR_WRITE	0x00040000	/* user can update key payload / add link to keyring */
+#define KEY_USR_SEARCH	0x00080000	/* user can find a key in search / search a keyring */
+#define KEY_USR_LINK	0x00100000	/* user can create a link to a key/keyring */
+#define KEY_USR_ALL	0x001f0000
+
+#define KEY_GRP_VIEW	0x00000100	/* group permissions... */
+#define KEY_GRP_READ	0x00000200
+#define KEY_GRP_WRITE	0x00000400
+#define KEY_GRP_SEARCH	0x00000800
+#define KEY_GRP_LINK	0x00001000
+#define KEY_GRP_ALL	0x00001f00
+
+#define KEY_OTH_VIEW	0x00000001	/* third party permissions... */
+#define KEY_OTH_READ	0x00000002
+#define KEY_OTH_WRITE	0x00000004
+#define KEY_OTH_SEARCH	0x00000008
+#define KEY_OTH_LINK	0x00000010
+#define KEY_OTH_ALL	0x0000001f
+
+struct seq_file;
+struct user_struct;
+
+struct key_type;
+struct key_owner;
+struct keyring_list;
+struct keyring_name;
+
+/*****************************************************************************/
+/*
+ * authentication token / access credential / keyring
+ * - types of key include:
+ *   - keyrings
+ *   - disk encryption IDs
+ *   - Kerberos TGTs and tickets
+ */
+struct key {
+	atomic_t		usage;		/* number of references */
+	key_serial_t		serial;		/* key serial number */
+	struct rb_node		serial_node;
+	struct key_type		*type;		/* type of key */
+	rwlock_t		lock;		/* examination vs change lock */
+	struct rw_semaphore	sem;		/* change vs change sem */
+	struct key_user		*user;		/* owner of this key */
+	time_t			expiry;		/* time at which key expires (or 0) */
+	uid_t			uid;
+	gid_t			gid;
+	key_perm_t		perm;		/* access permissions */
+	unsigned short		quotalen;	/* length added to quota */
+	unsigned short		datalen;	/* payload data length */
+	unsigned short		flags;		/* status flags (change with lock writelocked) */
+#define KEY_FLAG_INSTANTIATED	0x00000001	/* set if key has been instantiated */
+#define KEY_FLAG_DEAD		0x00000002	/* set if key type has been deleted */
+#define KEY_FLAG_REVOKED	0x00000004	/* set if key had been revoked */
+#define KEY_FLAG_IN_QUOTA	0x00000008	/* set if key consumes quota */
+#define KEY_FLAG_USER_CONSTRUCT	0x00000010	/* set if key is being constructed in userspace */
+#define KEY_FLAG_NEGATIVE	0x00000020	/* set if key is negative */
+
+#ifdef KEY_DEBUGGING
+	unsigned		magic;
+#define KEY_DEBUG_MAGIC		0x18273645u
+#define KEY_DEBUG_MAGIC_X	0xf8e9dacbu
+#endif
+
+	/* the description string
+	 * - this is used to match a key against search criteria
+	 * - this should be a printable string
+	 * - eg: for krb5 AFS, this might be "afs@REDHAT.COM"
+	 */
+	char			*description;
+
+	/* type specific data
+	 * - this is used by the keyring type to index the name
+	 */
+	union {
+		struct list_head	link;
+	} type_data;
+
+	/* key data
+	 * - this is used to hold the data actually used in cryptography or
+	 *   whatever
+	 */
+	union {
+		unsigned long		value;
+		void			*data;
+		struct keyring_list	*subscriptions;
+	} payload;
+};
+
+/*****************************************************************************/
+/*
+ * kernel managed key type definition
+ */
+struct key_type {
+	/* name of the type */
+	const char *name;
+
+	/* default payload length for quota precalculation (optional)
+	 * - this can be used instead of calling key_payload_reserve(), that
+	 *   function only needs to be called if the real datalen is different
+	 */
+	size_t def_datalen;
+
+	/* instantiate a key of this type
+	 * - this method should call key_payload_reserve() to determine if the
+	 *   user's quota will hold the payload
+	 */
+	int (*instantiate)(struct key *key, const void *data, size_t datalen);
+
+	/* duplicate a key of this type (optional)
+	 * - the source key will be locked against change
+	 * - the new description will be attached
+	 * - the quota will have been adjusted automatically from
+	 *   source->quotalen
+	 */
+	int (*duplicate)(struct key *key, const struct key *source);
+
+	/* update a key of this type (optional)
+	 * - this method should call key_payload_reserve() to recalculate the
+	 *   quota consumption
+	 * - the key must be locked against read when modifying
+	 */
+	int (*update)(struct key *key, const void *data, size_t datalen);
+
+	/* match a key against a description */
+	int (*match)(const struct key *key, const void *desc);
+
+	/* clear the data from a key (optional) */
+	void (*destroy)(struct key *key);
+
+	/* describe a key */
+	void (*describe)(const struct key *key, struct seq_file *p);
+
+	/* read a key's data (optional)
+	 * - permission checks will be done by the caller
+	 * - the key's semaphore will be readlocked by the caller
+	 * - should return the amount of data that could be read, no matter how
+	 *   much is copied into the buffer
+	 * - shouldn't do the copy if the buffer is NULL
+	 */
+	long (*read)(const struct key *key, char __user *buffer, size_t buflen);
+
+	/* internal fields */
+	struct list_head	link;		/* link in types list */
+};
+
+extern struct key_type key_type_keyring;
+
+extern int register_key_type(struct key_type *ktype);
+extern void unregister_key_type(struct key_type *ktype);
+
+extern struct key *key_alloc(struct key_type *type,
+			     const char *desc,
+			     uid_t uid, gid_t gid, key_perm_t perm,
+			     int not_in_quota);
+extern int key_payload_reserve(struct key *key, size_t datalen);
+extern int key_instantiate_and_link(struct key *key,
+				    const void *data,
+				    size_t datalen,
+				    struct key *keyring);
+extern int key_negate_and_link(struct key *key,
+			       unsigned timeout,
+			       struct key *keyring);
+extern void key_revoke(struct key *key);
+extern void key_put(struct key *key);
+
+static inline struct key *key_get(struct key *key)
+{
+	if (key)
+		atomic_inc(&key->usage);
+	return key;
+}
+
+extern struct key *request_key(struct key_type *type,
+			       const char *description,
+			       const char *callout_info);
+
+extern int key_validate(struct key *key);
+
+extern struct key *key_create_or_update(struct key *keyring,
+					const char *type,
+					const char *description,
+					const void *payload,
+					size_t plen,
+					int not_in_quota);
+
+extern int key_update(struct key *key,
+		      const void *payload,
+		      size_t plen);
+
+extern int key_link(struct key *keyring,
+		    struct key *key);
+
+extern int key_unlink(struct key *keyring,
+		      struct key *key);
+
+extern struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
+				 int not_in_quota, struct key *dest);
+
+extern int keyring_clear(struct key *keyring);
+
+extern struct key *keyring_search(struct key *keyring,
+				  struct key_type *type,
+				  const char *description);
+
+extern struct key *search_process_keyrings(struct key_type *type,
+					   const char *description);
+
+extern int keyring_add_key(struct key *keyring,
+			   struct key *key);
+
+extern struct key *key_lookup(key_serial_t id);
+
+#define key_serial(key) ((key) ? (key)->serial : 0)
+
+/*
+ * the userspace interface
+ */
+extern struct key root_user_keyring, root_session_keyring;
+extern int alloc_uid_keyring(struct user_struct *user);
+extern void switch_uid_keyring(struct user_struct *new_user);
+extern int copy_keys(unsigned long clone_flags, struct task_struct *tsk);
+extern void exit_keys(struct task_struct *tsk);
+extern int suid_keys(struct task_struct *tsk);
+extern int exec_keys(struct task_struct *tsk);
+extern void key_fsuid_changed(struct task_struct *tsk);
+extern void key_fsgid_changed(struct task_struct *tsk);
+
+#else /* CONFIG_KEYS */
+
+#define key_validate(k)			0
+#define key_serial(k)			0
+#define key_get(k) 			NULL
+#define key_put(k)			do { } while(0)
+#define alloc_uid_keyring(u)		0
+#define switch_uid_keyring(u)		do { } while(0)
+#define copy_keys(f,t)			0
+#define exit_keys(t)			do { } while(0)
+#define suid_keys(t)			do { } while(0)
+#define exec_keys(t)			do { } while(0)
+#define key_fsuid_changed(t)		do { } while(0)
+#define key_fsgid_changed(t)		do { } while(0)
+
+#endif /* CONFIG_KEYS */
+#endif /* __KERNEL__ */
+#endif /* _LINUX_KEY_H */
diff --git a/include/linux/keyctl.h b/include/linux/keyctl.h
new file mode 100644
index 000000000000..381dedc370a3
--- /dev/null
+++ b/include/linux/keyctl.h
@@ -0,0 +1,39 @@
+/* keyctl.h: keyctl command IDs
+ *
+ * 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.
+ */
+
+#ifndef _LINUX_KEYCTL_H
+#define _LINUX_KEYCTL_H
+
+/* special process keyring shortcut IDs */
+#define KEY_SPEC_THREAD_KEYRING		-1	/* - key ID for thread-specific keyring */
+#define KEY_SPEC_PROCESS_KEYRING	-2	/* - key ID for process-specific keyring */
+#define KEY_SPEC_SESSION_KEYRING	-3	/* - key ID for session-specific keyring */
+#define KEY_SPEC_USER_KEYRING		-4	/* - key ID for UID-specific keyring */
+#define KEY_SPEC_USER_SESSION_KEYRING	-5	/* - key ID for UID-session keyring */
+#define KEY_SPEC_GROUP_KEYRING		-6	/* - key ID for GID-specific keyring */
+
+/* keyctl commands */
+#define KEYCTL_GET_KEYRING_ID		0	/* ask for a keyring's ID */
+#define KEYCTL_JOIN_SESSION_KEYRING	1	/* join or start named session keyring */
+#define KEYCTL_UPDATE			2	/* update a key */
+#define KEYCTL_REVOKE			3	/* revoke a key */
+#define KEYCTL_CHOWN			4	/* set ownership of a key */
+#define KEYCTL_SETPERM			5	/* set perms on a key */
+#define KEYCTL_DESCRIBE			6	/* describe a key */
+#define KEYCTL_CLEAR			7	/* clear contents of a keyring */
+#define KEYCTL_LINK			8	/* link a key into a keyring */
+#define KEYCTL_UNLINK			9	/* unlink a key from a keyring */
+#define KEYCTL_SEARCH			10	/* search for a key in a keyring */
+#define KEYCTL_READ			11	/* read a key or keyring's contents */
+#define KEYCTL_INSTANTIATE		12	/* instantiate a partially constructed key */
+#define KEYCTL_NEGATE			13	/* negate a partially constructed key */
+
+#endif /*  _LINUX_KEYCTL_H */
diff --git a/include/linux/prctl.h b/include/linux/prctl.h
index 54333c98e532..edb036b43597 100644
--- a/include/linux/prctl.h
+++ b/include/linux/prctl.h
@@ -49,7 +49,6 @@
 # define PR_TIMING_TIMESTAMP    1       /* Accurate timestamp based
                                                    process timing */
 
-
 #define PR_SET_NAME    15		/* Set process name */
 
 #endif /* _LINUX_PRCTL_H */
diff --git a/include/linux/sched.h b/include/linux/sched.h
index dc3f297a726d..bbcd869e9304 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -358,6 +358,11 @@ struct user_struct {
 	unsigned long mq_bytes;	/* How many bytes can be allocated to mqueue? */
 	unsigned long locked_shm; /* How many pages of mlocked shm ? */
 
+#ifdef CONFIG_KEYS
+	struct key *uid_keyring;	/* UID specific keyring */
+	struct key *session_keyring;	/* UID's default session keyring */
+#endif
+
 	/* Hash table maintenance information */
 	struct list_head uidhash_list;
 	uid_t uid;
@@ -611,6 +616,11 @@ struct task_struct {
 	kernel_cap_t   cap_effective, cap_inheritable, cap_permitted;
 	unsigned keep_capabilities:1;
 	struct user_struct *user;
+#ifdef CONFIG_KEYS
+	struct key *session_keyring;	/* keyring inherited over fork */
+	struct key *process_keyring;	/* keyring private to this process (CLONE_THREAD) */
+	struct key *thread_keyring;	/* keyring private to this thread */
+#endif
 	unsigned short used_math;
 	char comm[16];
 /* file system info */
@@ -644,7 +654,7 @@ struct task_struct {
 /* Thread group tracking */
    	u32 parent_exec_id;
    	u32 self_exec_id;
-/* Protection of (de-)allocation: mm, files, fs, tty */
+/* Protection of (de-)allocation: mm, files, fs, tty, keyrings */
 	spinlock_t alloc_lock;
 /* Protection of proc_dentry: nesting proc_lock, dcache_lock, write_lock_irq(&tasklist_lock); */
 	spinlock_t proc_lock;
@@ -977,8 +987,8 @@ static inline int thread_group_empty(task_t *p)
 extern void unhash_process(struct task_struct *p);
 
 /*
- * Protects ->fs, ->files, ->mm, ->ptrace, ->group_info, ->comm and
- * synchronises with wait4().
+ * Protects ->fs, ->files, ->mm, ->ptrace, ->group_info, ->comm, keyring
+ * subscriptions and synchronises with wait4().  Also used in procfs.
  *
  * Nests both inside and outside of read_lock(&tasklist_lock).
  * It must not be nested with write_lock_irq(&tasklist_lock),
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 2a8c7faf2dcc..bc93606badbc 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -61,6 +61,7 @@ struct mq_attr;
 #include <asm/siginfo.h>
 #include <asm/signal.h>
 #include <linux/quota.h>
+#include <linux/key.h>
 
 asmlinkage long sys_time(int __user *tloc);
 asmlinkage long sys_stime(time_t __user *tptr);
@@ -492,4 +493,18 @@ asmlinkage long sys_uselib(const char __user *library);
 asmlinkage long sys_setaltroot(const char __user *altroot);
 asmlinkage long sys_ni_syscall(void);
 
+asmlinkage long sys_add_key(const char __user *_type,
+			    const char __user *_description,
+			    const void __user *_payload,
+			    size_t plen,
+			    key_serial_t destringid);
+
+asmlinkage long sys_request_key(const char __user *_type,
+				const char __user *_description,
+				const char __user *_callout_info,
+				key_serial_t destringid);
+
+asmlinkage long sys_keyctl(int cmd, unsigned long arg2, unsigned long arg3,
+			   unsigned long arg4, unsigned long arg5);
+
 #endif