KEYS: Add a system blacklist keyring
Add the following:
(1) A new system keyring that is used to store information about
blacklisted certificates and signatures.
(2) A new key type (called 'blacklist') that is used to store a
blacklisted hash in its description as a hex string. The key accepts
no payload.
(3) The ability to configure a list of blacklisted hashes into the kernel
at build time. This is done by setting
CONFIG_SYSTEM_BLACKLIST_HASH_LIST to the filename of a list of hashes
that are in the form:
"<hash>", "<hash>", ..., "<hash>"
where each <hash> is a hex string representation of the hash and must
include all necessary leading zeros to pad the hash to the right size.
The above are enabled with CONFIG_SYSTEM_BLACKLIST_KEYRING.
Once the kernel is booted, the blacklist keyring can be listed:
root@andromeda ~]# keyctl show %:.blacklist
Keyring
723359729 ---lswrv 0 0 keyring: .blacklist
676257228 ---lswrv 0 0 \_ blacklist: 123412341234c55c1dcc601ab8e172917706aa32fb5eaf826813547fdf02dd46
The blacklist cannot currently be modified by userspace, but it will be
possible to load it, for example, from the UEFI blacklist database.
A later commit will make it possible to load blacklisted asymmetric keys in
here too.
Signed-off-by: David Howells <dhowells@redhat.com>
diff --git a/certs/Kconfig b/certs/Kconfig
index fc5955f..6ce51ed 100644
--- a/certs/Kconfig
+++ b/certs/Kconfig
@@ -64,4 +64,22 @@
those keys are not blacklisted and are vouched for by a key built
into the kernel or already in the secondary trusted keyring.
+config SYSTEM_BLACKLIST_KEYRING
+ bool "Provide system-wide ring of blacklisted keys"
+ depends on KEYS
+ help
+ Provide a system keyring to which blacklisted keys can be added.
+ Keys in the keyring are considered entirely untrusted. Keys in this
+ keyring are used by the module signature checking to reject loading
+ of modules signed with a blacklisted key.
+
+config SYSTEM_BLACKLIST_HASH_LIST
+ string "Hashes to be preloaded into the system blacklist keyring"
+ depends on SYSTEM_BLACKLIST_KEYRING
+ help
+ If set, this option should be the filename of a list of hashes in the
+ form "<hash>", "<hash>", ... . This will be included into a C
+ wrapper to incorporate the list into the kernel. Each <hash> should
+ be a string of hex digits.
+
endmenu