From: Joe Richey <[email protected]>
Due to some interesting behaviour in keyctl (as described in the
comments), we use KEYCTL_GET_KEYRING_ID to translate the special value
of KEY_SPEC_SESSION_KEYRING to a real keyring id. However, how we
currently do this is flawed in two ways.
First, if KEYCTL_GET_KEYRING_ID fails, we don't detect it as it returns
-1 and zero is used for an error value in get_keyring_id. Second, if the
user specifies "-k @s" the translation never runs and the undesireable
behavior occurs.
These are both fixed by doing the translation outside of get_keyring_id.
Signed-off-by: Joe Richey <[email protected]>
---
misc/e4crypt.c | 37 +++++++++++++++++++++++--------------
1 file changed, 23 insertions(+), 14 deletions(-)
diff --git a/misc/e4crypt.c b/misc/e4crypt.c
index 04faca3..600d0b7 100644
--- a/misc/e4crypt.c
+++ b/misc/e4crypt.c
@@ -507,24 +507,12 @@ static int get_keyring_id(const char *keyring)
/*
* If no keyring is specified, by default use either the user
- * session key ring or the session keyring. Fetching the
+ * session keyring or the session keyring. Fetching the
* session keyring will return the user session keyring if no
* session keyring has been set.
- *
- * We need to do this instead of simply adding the key to
- * KEY_SPEC_SESSION_KEYRING since trying to add a key to a
- * session keyring that does not yet exist will cause the
- * kernel to create a session keyring --- which wil then get
- * garbage collected as soon as e4crypt exits.
- *
- * The fact that the keyctl system call and the add_key system
- * call treats KEY_SPEC_SESSION_KEYRING differently when a
- * session keyring does not exist is very unfortunate and
- * confusing, but so it goes...
*/
if (keyring == NULL)
- return keyctl(KEYCTL_GET_KEYRING_ID,
- KEY_SPEC_SESSION_KEYRING, 0);
+ return KEY_SPEC_SESSION_KEYRING;
for (x = 0; x < (sizeof(keyrings) / sizeof(keyrings[0])); ++x) {
if (strcmp(keyring, keyrings[x].name) == 0) {
return keyrings[x].code;
@@ -585,6 +573,27 @@ static void insert_key_into_keyring(const char *keyring, struct salt *salt)
key.mode = EXT4_ENCRYPTION_MODE_AES_256_XTS;
memcpy(key.raw, salt->key, EXT4_MAX_KEY_SIZE);
key.size = EXT4_MAX_KEY_SIZE;
+
+ /*
+ * We need to do this instead of simply adding the key to
+ * KEY_SPEC_SESSION_KEYRING since trying to add a key to a
+ * session keyring that does not yet exist will cause the
+ * kernel to create a session keyring --- which wil then get
+ * garbage collected as soon as e4crypt exits.
+ *
+ * The fact that the keyctl system call and the add_key system
+ * call treats KEY_SPEC_SESSION_KEYRING differently when a
+ * session keyring does not exist is very unfortunate and
+ * confusing, but so it goes...
+ */
+ if (keyring_id == KEY_SPEC_SESSION_KEYRING) {
+ keyring_id = keyctl(KEYCTL_GET_KEYRING_ID, keyring_id, 0);
+ if (keyring_id < 0) {
+ printf("Error getting session keyring ID: %s\n",
+ strerror(errno));
+ exit(1);
+ }
+ }
rc = add_key(EXT2FS_KEY_TYPE_LOGON, key_ref_full, (void *)&key,
sizeof(key), keyring_id);
if (rc == -1) {
--
2.7.4
On Mon, Apr 03, 2017 at 04:52:50PM +0000, Joe Richey wrote:
> From: Joe Richey <[email protected]>
>
> Due to some interesting behaviour in keyctl (as described in the
> comments), we use KEYCTL_GET_KEYRING_ID to translate the special value
> of KEY_SPEC_SESSION_KEYRING to a real keyring id. However, how we
> currently do this is flawed in two ways.
>
> First, if KEYCTL_GET_KEYRING_ID fails, we don't detect it as it returns
> -1 and zero is used for an error value in get_keyring_id. Second, if the
> user specifies "-k @s" the translation never runs and the undesireable
> behavior occurs.
>
> These are both fixed by doing the translation outside of get_keyring_id.
>
> Signed-off-by: Joe Richey <[email protected]>
Thanks, applied.
- Ted