Hi Herbert, while working on the AF_ALG interface, I saw no active zeroizations of memory that may hold sensitive data that is maintained outside the kernel crypto API cipher handles. I think the following memory segments fall under that category: * message digest * IV * plaintext / ciphertext handed in by consumer * ciphertext / plaintext that is send back to the consumer May I ask whether such zeroizations are present? At least I did not find it. If we conclude that there is a need for adding such zeroizations, I checked the code for the appropriate locations: I think I found the location for the first one: hash_sock_destruct that should be enhanced with a memset(0) of ctx->result. I have a patch ready which is tested and works. For the IV, I think I found the spot as well: skcipher_sock_destruct. This function should be enhanced with a memset(0) of ctx->iv. Again, I have a patch ready which is tested and works. However, I am failing to find the right spot to add a zeroization for the latter one, i.e. the code that handles the pages send in by the user or the pages that are returned by the crypto API. Initially I thought skcipher_pull_sgl is a good spot for the symmetric ciphers as it evicts the used pages out of the scope of the kernel crypto API. I added a clear_page(sg_page(sg+1)) as well as memset(sg_page(sg+1), 0, plen) right before the put_page call. All that I got in return was a BUG() from the memory management layer. Then I tried the same in af_alg_free_sg() as this function is used by algif_hash.c -- with the same result. That makes me wonder: where should such a zeroization call be added? Thanks -- Ciao Stephan -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
