Re: [PATCH] crypto: af_alg - Document the deprecation of AF_ALG

[Andy Lutomirski]

On Sun, May 10, 2026 at 9:33 AM Eric Biggers <ebiggers@xxxxxxxxxx> wrote:

> In any case, any hypothetical security benefit provided by AF_ALG would
> have to be *very high* to outweigh the continuous stream of
> vulnerabilities in it.  I understand that people using AF_ALG might not
> be familiar with that continuous stream of vulnerabilities, but it would
> be worth spending some time researching what has been going on.


It would not be completely crazy to have a simple, straightforward
interface by which user code could ask the kernel to do a
cryptographic operation.  Think:

int compute_keyed_hash(int key_fd, const void *data, size_t len);

where key_fd encodes both the key and the hash type (HMAC-SHA256 or
whatever), and there is a very, very small menu of hashes to choose
from.

But this is not really obviously worth the hassle.  And AF_ALG is
definitely not the right interface.