Re: Complete list of AF_ALG algorithms used by iwd

[James Prestwood]

Hi Eric,

On 5/3/26 9:50 PM, Eric Biggers wrote:
> With AF_ALG being on its way out due to its frequent vulnerabilities,
> iwd will need to be fixed to follow the standard practice of using
> userspace crypto code (for example, libcrypto) instead.  In the mean
> time, AF_ALG is at least going to need to be hardened by removing
> unnecessary functionality, for example unnecessary algorithms.
>
> Based on the iwd and libell source code, it appears iwd is relying on
> the following algorithm names from AF_ALG.  Please confirm that this
> list is correct and that these are the ones we need to keep for iwd:
>
>      cmac(aes)
>      hmac(md5)
>      hmac(sha1)
>      hmac(sha224)
>      hmac(sha256)
>      hmac(sha384)
>      hmac(sha512)
>      md4
>      md5
>      sha1
>      sha224
>      sha256
>      sha384
>      sha512
>      ecb(aes)
>      cbc(aes)
>      ctr(aes)
>      ecb(des)
>      cbc(des)
>      cbc(des3_ede)

This looks correct from IWD's standpoint, but ELL does support 
additional checksums:

- sha3-224
- sha3-256
- sha3-384
- sha3-512
- hmac(sha3-224)
- hmac(sha3-256)
- hmac(sha3-384)
- hmac(sha3-512)

Marcel may be able to comment on what projects are using these, if any.

> Also, does iwd always hold CAP_NET_ADMIN?  We're also considering adding
> a privilege check to AF_ALG.  (It's TBD whether it would be
> unconditional or controlled by a sysctl.)

Yes we require CAP_NET_ADMIN:

https://git.kernel.org/pub/scm/network/wireless/iwd.git/tree/src/iwd.service.in#n15


Thanks,

James

> - Eric