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authorDavid Howells <dhowells@redhat.com>2008-11-14 10:39:14 +1100
committerJames Morris <jmorris@namei.org>2008-11-14 10:39:14 +1100
commit8bbf4976b59fc9fc2861e79cab7beb3f6d647640 (patch)
tree9bd621217cbdfcf94aca5b220de7363254d7fc23 /include/linux
parente9e349b051d98799b743ebf248cc2d986fedf090 (diff)
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KEYS: Alter use of key instantiation link-to-keyring argument
Alter the use of the key instantiation and negation functions' link-to-keyring arguments. Currently this specifies a keyring in the target process to link the key into, creating the keyring if it doesn't exist. This, however, can be a problem for copy-on-write credentials as it means that the instantiating process can alter the credentials of the requesting process. This patch alters the behaviour such that: (1) If keyctl_instantiate_key() or keyctl_negate_key() are given a specific keyring by ID (ringid >= 0), then that keyring will be used. (2) If keyctl_instantiate_key() or keyctl_negate_key() are given one of the special constants that refer to the requesting process's keyrings (KEY_SPEC_*_KEYRING, all <= 0), then: (a) If sys_request_key() was given a keyring to use (destringid) then the key will be attached to that keyring. (b) If sys_request_key() was given a NULL keyring, then the key being instantiated will be attached to the default keyring as set by keyctl_set_reqkey_keyring(). (3) No extra link will be made. Decision point (1) follows current behaviour, and allows those instantiators who've searched for a specifically named keyring in the requestor's keyring so as to partition the keys by type to still have their named keyrings. Decision point (2) allows the requestor to make sure that the key or keys that get produced by request_key() go where they want, whilst allowing the instantiator to request that the key is retained. This is mainly useful for situations where the instantiator makes a secondary request, the key for which should be retained by the initial requestor: +-----------+ +--------------+ +--------------+ | | | | | | | Requestor |------->| Instantiator |------->| Instantiator | | | | | | | +-----------+ +--------------+ +--------------+ request_key() request_key() This might be useful, for example, in Kerberos, where the requestor requests a ticket, and then the ticket instantiator requests the TGT, which someone else then has to go and fetch. The TGT, however, should be retained in the keyrings of the requestor, not the first instantiator. To make this explict an extra special keyring constant is also added. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: James Morris <jmorris@namei.org> Signed-off-by: James Morris <jmorris@namei.org>
Diffstat (limited to 'include/linux')
-rw-r--r--include/linux/key.h16
-rw-r--r--include/linux/keyctl.h4
2 files changed, 11 insertions, 9 deletions
diff --git a/include/linux/key.h b/include/linux/key.h
index 1b70e35..df709e1 100644
--- a/include/linux/key.h
+++ b/include/linux/key.h
@@ -287,11 +287,11 @@ extern void key_fsuid_changed(struct task_struct *tsk);
extern void key_fsgid_changed(struct task_struct *tsk);
extern void key_init(void);
-#define __install_session_keyring(tsk, keyring) \
-({ \
- struct key *old_session = tsk->signal->session_keyring; \
- tsk->signal->session_keyring = keyring; \
- old_session; \
+#define __install_session_keyring(keyring) \
+({ \
+ struct key *old_session = current->signal->session_keyring; \
+ current->signal->session_keyring = keyring; \
+ old_session; \
})
#else /* CONFIG_KEYS */
@@ -302,11 +302,11 @@ extern void key_init(void);
#define key_revoke(k) do { } while(0)
#define key_put(k) do { } while(0)
#define key_ref_put(k) do { } while(0)
-#define make_key_ref(k, p) ({ NULL; })
-#define key_ref_to_ptr(k) ({ NULL; })
+#define make_key_ref(k, p) NULL
+#define key_ref_to_ptr(k) NULL
#define is_key_possessed(k) 0
#define switch_uid_keyring(u) do { } while(0)
-#define __install_session_keyring(t, k) ({ NULL; })
+#define __install_session_keyring(k) ({ NULL; })
#define copy_keys(f,t) 0
#define copy_thread_group_keys(t) 0
#define exit_keys(t) do { } while(0)
diff --git a/include/linux/keyctl.h b/include/linux/keyctl.h
index 656ee6b..c0688eb 100644
--- a/include/linux/keyctl.h
+++ b/include/linux/keyctl.h
@@ -1,6 +1,6 @@
/* keyctl.h: keyctl command IDs
*
- * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
+ * Copyright (C) 2004, 2008 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
@@ -20,6 +20,7 @@
#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 */
#define KEY_SPEC_REQKEY_AUTH_KEY -7 /* - key ID for assumed request_key auth key */
+#define KEY_SPEC_REQUESTOR_KEYRING -8 /* - key ID for request_key() dest keyring */
/* request-key default keyrings */
#define KEY_REQKEY_DEFL_NO_CHANGE -1
@@ -30,6 +31,7 @@
#define KEY_REQKEY_DEFL_USER_KEYRING 4
#define KEY_REQKEY_DEFL_USER_SESSION_KEYRING 5
#define KEY_REQKEY_DEFL_GROUP_KEYRING 6
+#define KEY_REQKEY_DEFL_REQUESTOR_KEYRING 7
/* keyctl commands */
#define KEYCTL_GET_KEYRING_ID 0 /* ask for a keyring's ID */