ANDROID: dm: use default verity public key
If the dm-android-verity target does not provide a default
key try using the default public key from the system keyring.
The defualt verity keyid is passed as a kernel command line
argument veritykeyid=.
The order of the dm-android-verity params have been reversed
to facilitate the change.
Old format example:
dm="system none ro,0 1 android-verity Android:#7e4333f9bba00adfe0ede979e28ed1920492b40f /dev/mmcblk0p43"
New formats supported:
dm="system none ro,0 1 android-verity /dev/mmcblk0p43 Android:#7e4333f9bba00adfe0ede979e28ed1920492b40f"
(or)
dm="system none ro,0 1 android-verity /dev/mmcblk0p43"
when veritykeyid= is set in the kernel command line.
BUG: 28384658
Signed-off-by: Badhri Jagan Sridharan <Badhri@google.com>
Change-Id: I506c89b053d835ab579e703eef2bc1f8487250de
(cherry picked from commit c5c74d0327729f35b576564976885596c6d0e7fb)
diff --git a/drivers/md/dm-android-verity.h b/drivers/md/dm-android-verity.h
index efb7965..43655ee 100644
--- a/drivers/md/dm-android-verity.h
+++ b/drivers/md/dm-android-verity.h
@@ -27,6 +27,22 @@
#define VERITY_TABLE_ARGS 10
#define VERITY_COMMANDLINE_PARAM_LENGTH 20
+/*
+ * <subject>:<sha1-id> is the format for the identifier.
+ * subject can either be the Common Name(CN) + Organization Name(O) or
+ * just the CN if the it is prefixed with O
+ * From https://tools.ietf.org/html/rfc5280#appendix-A
+ * ub-organization-name-length INTEGER ::= 64
+ * ub-common-name-length INTEGER ::= 64
+ *
+ * http://lxr.free-electrons.com/source/crypto/asymmetric_keys/x509_cert_parser.c?v=3.9#L278
+ * ctx->o_size + 2 + ctx->cn_size + 1
+ * + 41 characters for ":" and sha1 id
+ * 64 + 2 + 64 + 1 + 1 + 40 (172)
+ * setting VERITY_DEFAULT_KEY_ID_LENGTH to 200 characters.
+ */
+#define VERITY_DEFAULT_KEY_ID_LENGTH 200
+
#define FEC_MAGIC 0xFECFECFE
#define FEC_BLOCK_SIZE (4 * 1024)
#define FEC_VERSION 0