Commit f3a2ba44e93e2c ("certs: check-in the default x509 config file")
adds default x509 keypair config file template, but forgets to mention
it in kernel module signing documentation. Update the doc accordingly.
Signed-off-by: Bagas Sanjaya <bagasdotme@xxxxxxxxx>
---
Documentation/admin-guide/module-signing.rst | 41 ++++++++------------
1 file changed, 17 insertions(+), 24 deletions(-)
diff --git a/Documentation/admin-guide/module-signing.rst b/Documentation/admin-guide/module-signing.rst
index 7d7c7c8a545ca6..365d60a6245f17 100644
--- a/Documentation/admin-guide/module-signing.rst
+++ b/Documentation/admin-guide/module-signing.rst
@@ -133,46 +133,39 @@ kernel so that it can be used to check the signatures as the modules are
loaded.
Under normal conditions, when ``CONFIG_MODULE_SIG_KEY`` is unchanged from its
-default, the kernel build will automatically generate a new keypair using
-openssl if one does not exist in the file::
-
- certs/signing_key.pem
-
+default, the kernel build will automatically generate a new keypair in
+``certs/signing_key.pem`` using openssl if it doesn't exist,
during the building of vmlinux (the public part of the key needs to be built
-into vmlinux) using parameters in the::
-
- certs/x509.genkey
-
+into vmlinux) using parameters in the ``certs/x509.genkey`` configuration
file (which is also generated if it does not already exist).
-It is strongly recommended that you provide your own x509.genkey file.
-
-Most notably, in the x509.genkey file, the req_distinguished_name section
-should be altered from the default::
+If you'd like to provide alternative configuration, copy
+``certs/default_x509.genkey`` to ``certs/x509.genkey`` and edit the copy
+instead. Most likely, you will want to edit the ``req_distinguished_name``
+section, which identifies the resulting keypair. For example::
[ req_distinguished_name ]
- #O = Unspecified company
- CN = Build time autogenerated kernel key
- #emailAddress = unspecified.user@unspecified.company
+ O = Example company
+ CN = Example kernel build
+ emailAddress = user@xxxxxxxxxxx
The generated RSA key size can also be set with::
[ req ]
default_bits = 4096
-
-It is also possible to manually generate the key private/public files using the
-x509.genkey key generation configuration file in the root node of the Linux
-kernel sources tree and the openssl command. The following is an example to
-generate the public/private key files::
+Optionally, you can also manually generate the keypair so that the same
+keypair can be used in multiple builds. To generate it::
openssl req -new -nodes -utf8 -sha256 -days 36500 -batch -x509 \
-config x509.genkey -outform PEM -out kernel_key.pem \
-keyout kernel_key.pem
-The full pathname for the resulting kernel_key.pem file can then be specified
-in the ``CONFIG_MODULE_SIG_KEY`` option, and the certificate and key therein will
-be used instead of an autogenerated keypair.
+See :manpage:`openssl-req(1)` for the explanation.
+
+The full pathname for the resulting ``kernel_key.pem`` file can then be
+specified in the ``CONFIG_MODULE_SIG_KEY`` option, and the certificate and key
+therein will be used instead of an autogenerated keypair.
=========================
base-commit: ac9a78681b921877518763ba0e89202254349d1b
--
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