kernel/linux-3.1-keys-remove-special-keyring.patch

diff -up linux-3.1.x86_64/Documentation/networking/dns_resolver.txt.orig linux-3.1.x86_64/Documentation/networking/dns_resolver.txt
--- linux-3.1.x86_64/Documentation/networking/dns_resolver.txt.orig	2011-10-24 03:10:05.000000000 -0400
+++ linux-3.1.x86_64/Documentation/networking/dns_resolver.txt	2011-12-13 15:09:35.705766078 -0500
@@ -102,6 +102,10 @@ implemented in the module can be called
      If _expiry is non-NULL, the expiry time (TTL) of the result will be
      returned also.
 
+The kernel maintains an internal keyring in which it caches looked up keys.
+This can be cleared by any process that has the CAP_SYS_ADMIN capability by
+the use of KEYCTL_KEYRING_CLEAR on the keyring ID.
+
 
 ===============================
 READING DNS KEYS FROM USERSPACE
diff -up linux-3.1.x86_64/Documentation/security/keys.txt.orig linux-3.1.x86_64/Documentation/security/keys.txt
--- linux-3.1.x86_64/Documentation/security/keys.txt.orig	2011-10-24 03:10:05.000000000 -0400
+++ linux-3.1.x86_64/Documentation/security/keys.txt	2011-12-13 15:09:35.706766099 -0500
@@ -554,6 +554,10 @@ The keyctl syscall functions are:
      process must have write permission on the keyring, and it must be a
      keyring (or else error ENOTDIR will result).
 
+     This function can also be used to clear special kernel keyrings if they
+     are appropriately marked if the user has CAP_SYS_ADMIN capability.  The
+     DNS resolver cache keyring is an example of this.
+
 
  (*) Link a key into a keyring:
 
diff -up linux-3.1.x86_64/fs/cifs/cifsacl.c.orig linux-3.1.x86_64/fs/cifs/cifsacl.c
--- linux-3.1.x86_64/fs/cifs/cifsacl.c.orig	2011-12-13 12:54:12.221145867 -0500
+++ linux-3.1.x86_64/fs/cifs/cifsacl.c	2011-12-13 15:09:35.707766122 -0500
@@ -556,6 +556,7 @@ init_cifs_idmap(void)
 
 	/* instruct request_key() to use this special keyring as a cache for
 	 * the results it looks up */
+	set_bit(KEY_FLAG_ROOT_CAN_CLEAR, &keyring->flags);
 	cred->thread_keyring = keyring;
 	cred->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING;
 	root_cred = cred;
diff -up linux-3.1.x86_64/fs/nfs/idmap.c.orig linux-3.1.x86_64/fs/nfs/idmap.c
--- linux-3.1.x86_64/fs/nfs/idmap.c.orig	2011-12-13 12:54:14.657203507 -0500
+++ linux-3.1.x86_64/fs/nfs/idmap.c	2011-12-13 15:10:14.731681691 -0500
@@ -115,6 +115,7 @@ int nfs_idmap_init(void)
 	if (ret < 0)
 		goto failed_put_key;
 
+	set_bit(KEY_FLAG_ROOT_CAN_CLEAR, &keyring->flags);
 	cred->thread_keyring = keyring;
 	cred->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING;
 	id_resolver_cache = cred;
@@ -185,7 +186,7 @@ static ssize_t nfs_idmap_request_key(con
 	}
 
 	rcu_read_lock();
-	rkey->perm |= KEY_USR_VIEW;
+	rkey->perm |= KEY_USR_VIEW|KEY_USR_WRITE;
 
 	ret = key_validate(rkey);
 	if (ret < 0)
diff -up linux-3.1.x86_64/include/linux/key.h.orig linux-3.1.x86_64/include/linux/key.h
--- linux-3.1.x86_64/include/linux/key.h.orig	2011-10-24 03:10:05.000000000 -0400
+++ linux-3.1.x86_64/include/linux/key.h	2011-12-13 15:09:35.748767078 -0500
@@ -155,6 +155,7 @@ struct key {
 #define KEY_FLAG_IN_QUOTA	3	/* set if key consumes quota */
 #define KEY_FLAG_USER_CONSTRUCT	4	/* set if key is being constructed in userspace */
 #define KEY_FLAG_NEGATIVE	5	/* set if key is negative */
+#define KEY_FLAG_ROOT_CAN_CLEAR	6	/* set if key can be cleared by root without permission */
 
 	/* the description string
 	 * - this is used to match a key against search criteria
diff -up linux-3.1.x86_64/net/dns_resolver/dns_key.c.orig linux-3.1.x86_64/net/dns_resolver/dns_key.c
--- linux-3.1.x86_64/net/dns_resolver/dns_key.c.orig	2011-10-24 03:10:05.000000000 -0400
+++ linux-3.1.x86_64/net/dns_resolver/dns_key.c	2011-12-13 15:09:35.748767078 -0500
@@ -281,6 +281,7 @@ static int __init init_dns_resolver(void
 
 	/* instruct request_key() to use this special keyring as a cache for
 	 * the results it looks up */
+	set_bit(KEY_FLAG_ROOT_CAN_CLEAR, &keyring->flags);
 	cred->thread_keyring = keyring;
 	cred->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING;
 	dns_resolver_cache = cred;
diff -up linux-3.1.x86_64/security/keys/keyctl.c.orig linux-3.1.x86_64/security/keys/keyctl.c
--- linux-3.1.x86_64/security/keys/keyctl.c.orig	2011-12-13 12:54:30.322571289 -0500
+++ linux-3.1.x86_64/security/keys/keyctl.c	2011-12-13 15:09:35.756767271 -0500
@@ -388,11 +388,24 @@ long keyctl_keyring_clear(key_serial_t r
 	keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
 	if (IS_ERR(keyring_ref)) {
 		ret = PTR_ERR(keyring_ref);
+
+		/* Root is permitted to invalidate certain special keyrings */
+		if (capable(CAP_SYS_ADMIN)) {
+			keyring_ref = lookup_user_key(ringid, 0, 0);
+			if (IS_ERR(keyring_ref))
+				goto error;
+			if (test_bit(KEY_FLAG_ROOT_CAN_CLEAR,
+				     &key_ref_to_ptr(keyring_ref)->flags))
+				goto clear;
+			goto error_put;
+		}
+
 		goto error;
 	}
 
+clear:
 	ret = keyring_clear(key_ref_to_ptr(keyring_ref));
-
+error_put:
 	key_ref_put(keyring_ref);
 error:
 	return ret;