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author | Mimi Zohar <zohar@linux.vnet.ibm.com> | 2015-11-10 08:34:46 -0500 |
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committer | Mimi Zohar <zohar@linux.vnet.ibm.com> | 2015-12-15 10:01:43 -0500 |
commit | d3600bcf9d64d88dc1d189a754dcfab960ce751f (patch) | |
tree | 0db5cee0ddb99cfe1cbd7f8314653f36ddf5005f /security/keys/keyctl.c | |
parent | 80eae209d63ac6361c7b445f7e7e41f39c044772 (diff) | |
download | op-kernel-dev-d3600bcf9d64d88dc1d189a754dcfab960ce751f.zip op-kernel-dev-d3600bcf9d64d88dc1d189a754dcfab960ce751f.tar.gz |
KEYS: prevent keys from being removed from specified keyrings
Userspace should not be allowed to remove keys from certain keyrings
(eg. blacklist), though the keys themselves can expire.
This patch defines a new key flag named KEY_FLAG_KEEP to prevent
userspace from being able to unlink, revoke, invalidate or timed
out a key on a keyring. When this flag is set on the keyring, all
keys subsequently added are flagged.
In addition, when this flag is set, the keyring itself can not be
cleared.
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: David Howells <dhowells@redhat.com>
Diffstat (limited to 'security/keys/keyctl.c')
-rw-r--r-- | security/keys/keyctl.c | 56 |
1 files changed, 46 insertions, 10 deletions
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c index fb111ea..e83ec6b 100644 --- a/security/keys/keyctl.c +++ b/security/keys/keyctl.c @@ -358,11 +358,14 @@ error: * and any links to the key will be automatically garbage collected after a * certain amount of time (/proc/sys/kernel/keys/gc_delay). * + * Keys with KEY_FLAG_KEEP set should not be revoked. + * * If successful, 0 is returned. */ long keyctl_revoke_key(key_serial_t id) { key_ref_t key_ref; + struct key *key; long ret; key_ref = lookup_user_key(id, 0, KEY_NEED_WRITE); @@ -377,8 +380,13 @@ long keyctl_revoke_key(key_serial_t id) } } - key_revoke(key_ref_to_ptr(key_ref)); - ret = 0; + key = key_ref_to_ptr(key_ref); + if (test_bit(KEY_FLAG_KEEP, &key->flags)) + return -EPERM; + else { + key_revoke(key); + ret = 0; + } key_ref_put(key_ref); error: @@ -392,11 +400,14 @@ error: * The key and any links to the key will be automatically garbage collected * immediately. * + * Keys with KEY_FLAG_KEEP set should not be invalidated. + * * If successful, 0 is returned. */ long keyctl_invalidate_key(key_serial_t id) { key_ref_t key_ref; + struct key *key; long ret; kenter("%d", id); @@ -420,8 +431,13 @@ long keyctl_invalidate_key(key_serial_t id) } invalidate: - key_invalidate(key_ref_to_ptr(key_ref)); - ret = 0; + key = key_ref_to_ptr(key_ref); + if (test_bit(KEY_FLAG_KEEP, &key->flags)) + ret = -EPERM; + else { + key_invalidate(key); + ret = 0; + } error_put: key_ref_put(key_ref); error: @@ -433,12 +449,13 @@ error: * Clear the specified keyring, creating an empty process keyring if one of the * special keyring IDs is used. * - * The keyring must grant the caller Write permission for this to work. If - * successful, 0 will be returned. + * The keyring must grant the caller Write permission and not have + * KEY_FLAG_KEEP set for this to work. If successful, 0 will be returned. */ long keyctl_keyring_clear(key_serial_t ringid) { key_ref_t keyring_ref; + struct key *keyring; long ret; keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE); @@ -460,7 +477,11 @@ long keyctl_keyring_clear(key_serial_t ringid) } clear: - ret = keyring_clear(key_ref_to_ptr(keyring_ref)); + keyring = key_ref_to_ptr(keyring_ref); + if (test_bit(KEY_FLAG_KEEP, &keyring->flags)) + ret = -EPERM; + else + ret = keyring_clear(keyring); error_put: key_ref_put(keyring_ref); error: @@ -511,11 +532,14 @@ error: * itself need not grant the caller anything. If the last link to a key is * removed then that key will be scheduled for destruction. * + * Keys or keyrings with KEY_FLAG_KEEP set should not be unlinked. + * * If successful, 0 will be returned. */ long keyctl_keyring_unlink(key_serial_t id, key_serial_t ringid) { key_ref_t keyring_ref, key_ref; + struct key *keyring, *key; long ret; keyring_ref = lookup_user_key(ringid, 0, KEY_NEED_WRITE); @@ -530,7 +554,13 @@ long keyctl_keyring_unlink(key_serial_t id, key_serial_t ringid) goto error2; } - ret = key_unlink(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref)); + keyring = key_ref_to_ptr(keyring_ref); + key = key_ref_to_ptr(key_ref); + if (test_bit(KEY_FLAG_KEEP, &keyring->flags) && + test_bit(KEY_FLAG_KEEP, &key->flags)) + ret = -EPERM; + else + ret = key_unlink(keyring, key); key_ref_put(key_ref); error2: @@ -1289,6 +1319,8 @@ error: * the current time. The key and any links to the key will be automatically * garbage collected after the timeout expires. * + * Keys with KEY_FLAG_KEEP set should not be timed out. + * * If successful, 0 is returned. */ long keyctl_set_timeout(key_serial_t id, unsigned timeout) @@ -1320,10 +1352,14 @@ long keyctl_set_timeout(key_serial_t id, unsigned timeout) okay: key = key_ref_to_ptr(key_ref); - key_set_timeout(key, timeout); + if (test_bit(KEY_FLAG_KEEP, &key->flags)) + ret = -EPERM; + else { + key_set_timeout(key, timeout); + ret = 0; + } key_put(key); - ret = 0; error: return ret; } |