path: root/security/keys/request_key_auth.c
diff options
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 /security/keys/request_key_auth.c
parentKEYS: Disperse linux/key_ui.h (diff)
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 'security/keys/request_key_auth.c')
1 files changed, 4 insertions, 1 deletions
diff --git a/security/keys/request_key_auth.c b/security/keys/request_key_auth.c
index 729156b3485e..1762d44711d5 100644
--- a/security/keys/request_key_auth.c
+++ b/security/keys/request_key_auth.c
@@ -128,6 +128,7 @@ static void request_key_auth_destroy(struct key *key)
+ key_put(rka->dest_keyring);
@@ -139,7 +140,7 @@ static void request_key_auth_destroy(struct key *key)
* access to the caller's security data
struct key *request_key_auth_new(struct key *target, const void *callout_info,
- size_t callout_len)
+ size_t callout_len, struct key *dest_keyring)
struct request_key_auth *rka, *irka;
struct key *authkey = NULL;
@@ -188,6 +189,7 @@ struct key *request_key_auth_new(struct key *target, const void *callout_info,
rka->target_key = key_get(target);
+ rka->dest_keyring = key_get(dest_keyring);
memcpy(rka->callout_info, callout_info, callout_len);
rka->callout_len = callout_len;
@@ -223,6 +225,7 @@ error_inst:
+ key_put(rka->dest_keyring);
kleave("= %d", ret);