On Mon, Feb 12, 2024 at 12:48 PM Stefan Berger [off-list ref] wrote:

On 1/15/24 13:18, Roberto Sassu wrote:

...

quoted

+/**
+ * ima_kernel_module_request - Prevent crypto-pkcs1pad(rsa,*) requests
+ * @kmod_name: kernel module name
+ *
+ * We have situation, when public_key_verify_signature() in case of RSA > + * algorithm use alg_name to store internal information in order to
+ * construct an algorithm on the fly, but crypto_larval_lookup() will try
+ * to use alg_name in order to load kernel module with same name.
+ * Since we don't have any real "crypto-pkcs1pad(rsa,*)" kernel modules,
+ * we are safe to fail such module request from crypto_larval_lookup().
+ *
+ * In this way we prevent modprobe execution during digsig verification
+ * and avoid possible deadlock if modprobe and/or it's dependencies
+ * also signed with digsig.

This text needs to some reformulation at some point..

There is no time like the present.  If you have a suggestion I would
love to hear it and I'm sure Roberto would too.

-- 
paul-moore.com