From: Karl Mehltretter <kmehltretter@gmail.com>
To: Eric Biggers <ebiggers@kernel.org>
Cc: bpf@vger.kernel.org, Vadim Fedorenko <vadim.fedorenko@linux.dev>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Eduard Zingerman <eddyz87@gmail.com>,
Kumar Kartikeya Dwivedi <memxor@gmail.com>,
linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org,
Martin KaFai Lau <martin.lau@linux.dev>,
Song Liu <song@kernel.org>,
Yonghong Song <yonghong.song@linux.dev>,
Jiri Olsa <jolsa@kernel.org>,
Emil Tsalapatis <emil@etsalapatis.com>,
Ihor Solodrai <ihor.solodrai@linux.dev>,
John Fastabend <john.fastabend@gmail.com>
Subject: Re: [PATCH bpf-next] bpf: crypto: Use AES-CBC and AES-ECB libraries
Date: Mon, 31 Aug 2026 23:25:54 +0200 [thread overview]
Message-ID: <apXwXLRpBUIWQuC5@gmail.com> (raw)
In-Reply-To: <20260831192139.94895-1-ebiggers@kernel.org>
On Mon, Aug 31, 2026 at 12:21:39PM +0100, Eric Biggers wrote:
> There are library APIs for both of these now, which are much easier to
> use and more efficient. Reimplement BPF crypto on top of them, greatly
> simplifying the code. As part of this, the bpf_crypto_type abstraction
> layer is removed, as it's not useful.
>
This relates to my recent patch fixing state preservation in lskcipher's
unaligned path, which exercised ARC4 through BPF:
https://lore.kernel.org/r/20260829194314.42685-1-kmehltretter@gmail.com
While looking at your patch, I tested the actual BPF-visible algorithm
surface. The ECB and CBC templates allow considerably more than AES.
I compared:
A: cee9395acd80 (v7.3-rc1)
B: cee9395acd80 plus this patch
both used the same arm64 QEMU configuration and the same BPF/userspace
test artifacts. Each request was exactly one cipher block.
"OK" means context creation plus BPF encrypt/decrypt round-trip succeeded.
Algorithm Bytes A B
--------------------------------------------------------
ecb(aes) 16 OK OK
cbc(aes) 16 OK OK
ecb(aes-lib) 16 OK -ENOENT
cbc(aes-lib) 16 OK -ENOENT
ecb(anubis) 16 OK -ENOENT
cbc(anubis) 16 OK -ENOENT
ecb(anubis-generic) 16 OK -ENOENT
cbc(anubis-generic) 16 OK -ENOENT
ecb(aria) 16 OK -ENOENT
cbc(aria) 16 OK -ENOENT
ecb(aria-generic) 16 OK -ENOENT
cbc(aria-generic) 16 OK -ENOENT
ecb(blowfish) 8 OK -ENOENT
cbc(blowfish) 8 OK -ENOENT
ecb(blowfish-generic) 8 OK -ENOENT
cbc(blowfish-generic) 8 OK -ENOENT
ecb(camellia) 16 OK -ENOENT
cbc(camellia) 16 OK -ENOENT
ecb(camellia-generic) 16 OK -ENOENT
cbc(camellia-generic) 16 OK -ENOENT
ecb(cast5) 8 OK -ENOENT
cbc(cast5) 8 OK -ENOENT
ecb(cast5-generic) 8 OK -ENOENT
cbc(cast5-generic) 8 OK -ENOENT
ecb(cast6) 16 OK -ENOENT
cbc(cast6) 16 OK -ENOENT
ecb(cast6-generic) 16 OK -ENOENT
cbc(cast6-generic) 16 OK -ENOENT
ecb(des) 8 OK -ENOENT
cbc(des) 8 OK -ENOENT
ecb(des-generic) 8 OK -ENOENT
cbc(des-generic) 8 OK -ENOENT
ecb(des3_ede) 8 OK -ENOENT
cbc(des3_ede) 8 OK -ENOENT
ecb(des3_ede-generic) 8 OK -ENOENT
cbc(des3_ede-generic) 8 OK -ENOENT
ecb(khazad) 8 OK -ENOENT
cbc(khazad) 8 OK -ENOENT
ecb(khazad-generic) 8 OK -ENOENT
cbc(khazad-generic) 8 OK -ENOENT
ecb(seed) 16 OK -ENOENT
cbc(seed) 16 OK -ENOENT
ecb(seed-generic) 16 OK -ENOENT
cbc(seed-generic) 16 OK -ENOENT
ecb(serpent) 16 OK -ENOENT
cbc(serpent) 16 OK -ENOENT
ecb(serpent-generic) 16 OK -ENOENT
cbc(serpent-generic) 16 OK -ENOENT
ecb(sm4) 16 OK -ENOENT
cbc(sm4) 16 OK -ENOENT
ecb(sm4-generic) 16 OK -ENOENT
cbc(sm4-generic) 16 OK -ENOENT
ecb(tea) 8 OK -ENOENT
cbc(tea) 8 OK -ENOENT
ecb(tea-generic) 8 OK -ENOENT
cbc(tea-generic) 8 OK -ENOENT
ecb(xtea) 8 OK -ENOENT
cbc(xtea) 8 OK -ENOENT
ecb(xtea-generic) 8 OK -ENOENT
cbc(xtea-generic) 8 OK -ENOENT
ecb(xeta) 8 OK -ENOENT
cbc(xeta) 8 OK -ENOENT
ecb(xeta-generic) 8 OK -ENOENT
cbc(xeta-generic) 8 OK -ENOENT
ecb(twofish) 16 OK -ENOENT
cbc(twofish) 16 OK -ENOENT
ecb(twofish-generic) 16 OK -ENOENT
cbc(twofish-generic) 16 OK -ENOENT
arc4 1 OK -ENOENT
arc4-generic 1 OK -ENOENT
ecb(arc4) 1 OK -ENOENT
ecb(arc4-generic) 1 OK -ENOENT
This leaves only 2 of the 72 tested algorithm names: the other 70,
covering AES aliases, non-AES block ciphers, and ARC4, now return
-ENOENT.
This table describes the BPF-visible support removed by this patch. That
may well be worthwhile cleanup, but it is still the removal of existing,
likely only theoretical, support.
Thanks,
Karl
next prev parent reply other threads:[~2026-08-31 21:25 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-31 19:21 [PATCH bpf-next] bpf: crypto: Use AES-CBC and AES-ECB libraries Eric Biggers
2026-08-31 20:29 ` bot+bpf-ci
2026-08-31 21:59 ` Eric Biggers
2026-08-31 22:43 ` Eric Biggers
2026-08-31 21:25 ` Karl Mehltretter [this message]
2026-08-31 21:48 ` Eric Biggers
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