Merge tag 'keys-acl-20190703' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs

Pull keyring ACL support from David Howells:
 "This changes the permissions model used by keys and keyrings to be
  based on an internal ACL by the following means:

   - Replace the permissions mask internally with an ACL that contains a
     list of ACEs, each with a specific subject with a permissions mask.
     Potted default ACLs are available for new keys and keyrings.

     ACE subjects can be macroised to indicate the UID and GID specified
     on the key (which remain). Future commits will be able to add
     additional subject types, such as specific UIDs or domain
     tags/namespaces.

     Also split a number of permissions to give finer control. Examples
     include splitting the revocation permit from the change-attributes
     permit, thereby allowing someone to be granted permission to revoke
     a key without allowing them to change the owner; also the ability
     to join a keyring is split from the ability to link to it, thereby
     stopping a process accessing a keyring by joining it and thus
     acquiring use of possessor permits.

   - Provide a keyctl to allow the granting or denial of one or more
     permits to a specific subject. Direct access to the ACL is not
     granted, and the ACL cannot be viewed"

* tag 'keys-acl-20190703' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
  keys: Provide KEYCTL_GRANT_PERMISSION
  keys: Replace uid/gid/perm permissions checking with an ACL

2 files changed, 131 insertions, 55 deletions

diff --git a/include/linux/key.h b/include/linux/key.h
index 91f391cd272e..6fef6684501f 100644
--- a/include/linux/key.h
+++ b/include/linux/key.h
@@ -27,49 +27,14 @@
 /* key handle serial number */
 typedef int32_t key_serial_t;
 
-/* key handle permissions mask */
-typedef uint32_t key_perm_t;
-
 struct key;
 struct net;
 
 #ifdef CONFIG_KEYS
 
-#undef KEY_DEBUGGING
+#include <linux/keyctl.h>
 
-#define KEY_POS_VIEW	0x01000000	/* possessor can view a key's attributes */
-#define KEY_POS_READ	0x02000000	/* possessor can read key payload / view keyring */
-#define KEY_POS_WRITE	0x04000000	/* possessor can update key payload / add link to keyring */
-#define KEY_POS_SEARCH	0x08000000	/* possessor can find a key in search / search a keyring */
-#define KEY_POS_LINK	0x10000000	/* possessor can create a link to a key/keyring */
-#define KEY_POS_SETATTR	0x20000000	/* possessor can set key attributes */
-#define KEY_POS_ALL	0x3f000000
-
-#define KEY_USR_VIEW	0x00010000	/* user permissions... */
-#define KEY_USR_READ	0x00020000
-#define KEY_USR_WRITE	0x00040000
-#define KEY_USR_SEARCH	0x00080000
-#define KEY_USR_LINK	0x00100000
-#define KEY_USR_SETATTR	0x00200000
-#define KEY_USR_ALL	0x003f0000
-
-#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_SETATTR	0x00002000
-#define KEY_GRP_ALL	0x00003f00
-
-#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_SETATTR	0x00000020
-#define KEY_OTH_ALL	0x0000003f
-
-#define KEY_PERM_UNDEF	0xffffffff
+#undef KEY_DEBUGGING
 
 struct seq_file;
 struct user_struct;
@@ -113,6 +78,36 @@ union key_payload {
 	void			*data[4];
 };
 
+struct key_ace {
+	unsigned int		type;
+	unsigned int		perm;
+	union {
+		kuid_t		uid;
+		kgid_t		gid;
+		unsigned int	subject_id;
+	};
+};
+
+struct key_acl {
+	refcount_t		usage;
+	unsigned short		nr_ace;
+	bool			possessor_viewable;
+	struct rcu_head		rcu;
+	struct key_ace		aces[];
+};
+
+#define KEY_POSSESSOR_ACE(perms) {			\
+		.type = KEY_ACE_SUBJ_STANDARD,		\
+		.perm = perms,				\
+		.subject_id = KEY_ACE_POSSESSOR		\
+	}
+
+#define KEY_OWNER_ACE(perms) {				\
+		.type = KEY_ACE_SUBJ_STANDARD,		\
+		.perm = perms,				\
+		.subject_id = KEY_ACE_OWNER		\
+	}
+
 /*****************************************************************************/
 /*
  * key reference with possession attribute handling
@@ -179,6 +174,7 @@ struct key {
 	struct rw_semaphore	sem;		/* change vs change sem */
 	struct key_user		*user;		/* owner of this key */
 	void			*security;	/* security data for this key */
+	struct key_acl		__rcu *acl;
 	union {
 		time64_t	expiry;		/* time at which key expires (or 0) */
 		time64_t	revoked_at;	/* time at which key was revoked */
@@ -186,7 +182,6 @@ struct key {
 	time64_t		last_used_at;	/* last time used for LRU keyring discard */
 	kuid_t			uid;
 	kgid_t			gid;
-	key_perm_t		perm;		/* access permissions */
 	unsigned short		quotalen;	/* length added to quota */
 	unsigned short		datalen;	/* payload data length
 						 * - may not match RCU dereferenced payload
@@ -210,6 +205,7 @@ struct key {
 #define KEY_FLAG_ROOT_CAN_INVAL	7	/* set if key can be invalidated by root without permission */
 #define KEY_FLAG_KEEP		8	/* set if key should not be removed */
 #define KEY_FLAG_UID_KEYRING	9	/* set if key is a user or user session keyring */
+#define KEY_FLAG_HAS_ACL	10	/* Set if KEYCTL_SETACL called on key */
 
 	/* the key type and key description string
 	 * - the desc is used to match a key against search criteria
@@ -258,7 +254,7 @@ extern struct key *key_alloc(struct key_type *type,
 			     const char *desc,
 			     kuid_t uid, kgid_t gid,
 			     const struct cred *cred,
-			     key_perm_t perm,
+			     struct key_acl *acl,
 			     unsigned long flags,
 			     struct key_restriction *restrict_link);
 
@@ -295,7 +291,8 @@ static inline void key_ref_put(key_ref_t key_ref)
 extern struct key *request_key_tag(struct key_type *type,
 				   const char *description,
 				   struct key_tag *domain_tag,
-				   const char *callout_info);
+				   const char *callout_info,
+				   struct key_acl *acl);
 
 extern struct key *request_key_rcu(struct key_type *type,
 				   const char *description,
@@ -306,21 +303,24 @@ extern struct key *request_key_with_auxdata(struct key_type *type,
 					    struct key_tag *domain_tag,
 					    const void *callout_info,
 					    size_t callout_len,
-					    void *aux);
+					    void *aux,
+					    struct key_acl *acl);
 
 /**
  * request_key - Request a key and wait for construction
  * @type: Type of key.
  * @description: The searchable description of the key.
  * @callout_info: The data to pass to the instantiation upcall (or NULL).
+ * @acl: The ACL to attach to a new key (or NULL).
  *
  * As for request_key_tag(), but with the default global domain tag.
  */
 static inline struct key *request_key(struct key_type *type,
 				      const char *description,
-				      const char *callout_info)
+				      const char *callout_info,
+				      struct key_acl *acl)
 {
-	return request_key_tag(type, description, NULL, callout_info);
+	return request_key_tag(type, description, NULL, callout_info, acl);
 }
 
 #ifdef CONFIG_NET
@@ -330,6 +330,7 @@ static inline struct key *request_key(struct key_type *type,
  * @description: The searchable description of the key.
  * @net: The network namespace that is the key's domain of operation.
  * @callout_info: The data to pass to the instantiation upcall (or NULL).
+ * @acl: The ACL to attach to a new key (or NULL).
  *
  * As for request_key() except that it does not add the returned key to a
  * keyring if found, new keys are always allocated in the user's quota, the
@@ -339,8 +340,8 @@ static inline struct key *request_key(struct key_type *type,
  * Furthermore, it then works as wait_for_key_construction() to wait for the
  * completion of keys undergoing construction with a non-interruptible wait.
  */
-#define request_key_net(type, description, net, callout_info) \
-	request_key_tag(type, description, net->key_domain, callout_info);
+#define request_key_net(type, description, net, callout_info, acl)	\
+	request_key_tag(type, description, net->key_domain, callout_info, acl);
 #endif /* CONFIG_NET */
 
 extern int wait_for_key_construction(struct key *key, bool intr);
@@ -352,7 +353,7 @@ extern key_ref_t key_create_or_update(key_ref_t keyring,
 				      const char *description,
 				      const void *payload,
 				      size_t plen,
-				      key_perm_t perm,
+				      struct key_acl *acl,
 				      unsigned long flags);
 
 extern int key_update(key_ref_t key,
@@ -372,7 +373,7 @@ extern int key_unlink(struct key *keyring,
 
 extern struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
 				 const struct cred *cred,
-				 key_perm_t perm,
+				 struct key_acl *acl,
 				 unsigned long flags,
 				 struct key_restriction *restrict_link,
 				 struct key *dest);
@@ -405,19 +406,29 @@ static inline key_serial_t key_serial(const struct key *key)
 extern void key_set_timeout(struct key *, unsigned);
 
 extern key_ref_t lookup_user_key(key_serial_t id, unsigned long flags,
-				 key_perm_t perm);
+				 u32 desired_perm);
 extern void key_free_user_ns(struct user_namespace *);
 
 /*
  * The permissions required on a key that we're looking up.
  */
-#define	KEY_NEED_VIEW	0x01	/* Require permission to view attributes */
-#define	KEY_NEED_READ	0x02	/* Require permission to read content */
-#define	KEY_NEED_WRITE	0x04	/* Require permission to update / modify */
-#define	KEY_NEED_SEARCH	0x08	/* Require permission to search (keyring) or find (key) */
-#define	KEY_NEED_LINK	0x10	/* Require permission to link */
-#define	KEY_NEED_SETATTR 0x20	/* Require permission to change attributes */
-#define	KEY_NEED_ALL	0x3f	/* All the above permissions */
+#define	KEY_NEED_VIEW	0x001	/* Require permission to view attributes */
+#define	KEY_NEED_READ	0x002	/* Require permission to read content */
+#define	KEY_NEED_WRITE	0x004	/* Require permission to update / modify */
+#define	KEY_NEED_SEARCH	0x008	/* Require permission to search (keyring) or find (key) */
+#define	KEY_NEED_LINK	0x010	/* Require permission to link */
+#define	KEY_NEED_SETSEC	0x020	/* Require permission to set owner, group, ACL */
+#define	KEY_NEED_INVAL	0x040	/* Require permission to invalidate key */
+#define	KEY_NEED_REVOKE	0x080	/* Require permission to revoke key */
+#define	KEY_NEED_JOIN	0x100	/* Require permission to join keyring as session */
+#define	KEY_NEED_CLEAR	0x200	/* Require permission to clear a keyring */
+#define KEY_NEED_ALL	0x3ff
+
+#define OLD_KEY_NEED_SETATTR 0x20 /* Used to be Require permission to change attributes */
+
+extern struct key_acl internal_key_acl;
+extern struct key_acl internal_keyring_acl;
+extern struct key_acl internal_writable_keyring_acl;
 
 static inline short key_read_state(const struct key *key)
 {
diff --git a/include/uapi/linux/keyctl.h b/include/uapi/linux/keyctl.h
index ed3d5893830d..1f7a4e737214 100644
--- a/include/uapi/linux/keyctl.h
+++ b/include/uapi/linux/keyctl.h
@@ -15,6 +15,69 @@
 
 #include <linux/types.h>
 
+/*
+ * Keyring permission grant definitions
+ */
+enum key_ace_subject_type {
+	KEY_ACE_SUBJ_STANDARD	= 0,	/* subject is one of key_ace_standard_subject */
+	nr__key_ace_subject_type
+};
+
+enum key_ace_standard_subject {
+	KEY_ACE_EVERYONE	= 0,	/* Everyone, including owner and group */
+	KEY_ACE_GROUP		= 1,	/* The key's group */
+	KEY_ACE_OWNER		= 2,	/* The owner of the key */
+	KEY_ACE_POSSESSOR	= 3,	/* Any process that possesses of the key */
+	nr__key_ace_standard_subject
+};
+
+#define KEY_ACE_VIEW		0x00000001 /* Can describe the key */
+#define KEY_ACE_READ		0x00000002 /* Can read the key content */
+#define KEY_ACE_WRITE		0x00000004 /* Can update/modify the key content */
+#define KEY_ACE_SEARCH		0x00000008 /* Can find the key by search */
+#define KEY_ACE_LINK		0x00000010 /* Can make a link to the key */
+#define KEY_ACE_SET_SECURITY	0x00000020 /* Can set owner, group, ACL */
+#define KEY_ACE_INVAL		0x00000040 /* Can invalidate the key */
+#define KEY_ACE_REVOKE		0x00000080 /* Can revoke the key */
+#define KEY_ACE_JOIN		0x00000100 /* Can join keyring */
+#define KEY_ACE_CLEAR		0x00000200 /* Can clear keyring */
+#define KEY_ACE__PERMS		0xffffffff
+
+/*
+ * Old-style permissions mask, deprecated in favour of ACL.
+ */
+#define KEY_POS_VIEW	0x01000000	/* possessor can view a key's attributes */
+#define KEY_POS_READ	0x02000000	/* possessor can read key payload / view keyring */
+#define KEY_POS_WRITE	0x04000000	/* possessor can update key payload / add link to keyring */
+#define KEY_POS_SEARCH	0x08000000	/* possessor can find a key in search / search a keyring */
+#define KEY_POS_LINK	0x10000000	/* possessor can create a link to a key/keyring */
+#define KEY_POS_SETATTR	0x20000000	/* possessor can set key attributes */
+#define KEY_POS_ALL	0x3f000000
+
+#define KEY_USR_VIEW	0x00010000	/* user permissions... */
+#define KEY_USR_READ	0x00020000
+#define KEY_USR_WRITE	0x00040000
+#define KEY_USR_SEARCH	0x00080000
+#define KEY_USR_LINK	0x00100000
+#define KEY_USR_SETATTR	0x00200000
+#define KEY_USR_ALL	0x003f0000
+
+#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_SETATTR	0x00002000
+#define KEY_GRP_ALL	0x00003f00
+
+#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_SETATTR	0x00000020
+#define KEY_OTH_ALL	0x0000003f
+
 /* 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 */
@@ -69,6 +132,7 @@
 #define KEYCTL_RESTRICT_KEYRING		29	/* Restrict keys allowed to link to a keyring */
 #define KEYCTL_MOVE			30	/* Move keys between keyrings */
 #define KEYCTL_CAPABILITIES		31	/* Find capabilities of keyrings subsystem */
+#define KEYCTL_GRANT_PERMISSION		32	/* Grant a permit to a key */
 
 /* keyctl structures */
 struct keyctl_dh_params {
@@ -130,5 +194,6 @@ struct keyctl_pkey_params {
 #define KEYCTL_CAPS0_MOVE		0x80 /* KEYCTL_MOVE supported */
 #define KEYCTL_CAPS1_NS_KEYRING_NAME	0x01 /* Keyring names are per-user_namespace */
 #define KEYCTL_CAPS1_NS_KEY_TAG		0x02 /* Key indexing can include a namespace tag */
+#define KEYCTL_CAPS1_ACL_ALTERABLE	0x04 /* Keys have internal ACL that can be altered */
 
 #endif /*  _LINUX_KEYCTL_H */