bpf: crypto: Use AES-CBC and AES-ECB libraries

BPF crypto was implemented using the lskcipher API, which doesn't seem
to be going anywhere.  lskcipher supports only ARC4 and block ciphers in
CBC and ECB mode, and only with unoptimized implementations.

Library APIs also have been found to be a much better approach, for a
variety of reasons, including reduced overhead, greater flexibility, and
having to be explicit about the crypto algorithms that are supported.

We can safely ignore the theoretical ARC4 and non-AES block cipher
support in BPF crypto as unused, which leaves AES-CBC and AES-ECB.
AES-CBC was stated to be needed for decrypting packets using a homebrew
UDP-based protocol
(https://lore.kernel.org/r/d1cdfc23-b336-49a9-8833-29f05b5b9fec@linux.dev/).
AES-ECB is used by the BPF self-tests, and it was stated to maybe be
used in the future for QUIC-LB
(https://lore.kernel.org/r/5f9c3aab-5339-463c-a86d-edac297e1e95@linux.dev/).

Those reasons don't make much sense either, especially AES-ECB which
isn't appropriate in new systems and should be dropped.  Regardless,
let's assume that both AES-CBC and AES-ECB need to be kept for now.

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 removes the only user of the lskcipher API, so follow-up patches
will be able to remove that code as well.

Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://patch.msgid.link/20260924184254.142720-1-ebiggers@kernel.org

1 files changed, 0 insertions, 24 deletions

diff --git a/include/linux/bpf_crypto.h b/include/linux/bpf_crypto.h
deleted file mode 100644
index a41e71d4e2d9..000000000000
--- a/include/linux/bpf_crypto.h
+++ /dev/null
@@ -1,24 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-only */
-/* Copyright (c) 2024 Meta Platforms, Inc. and affiliates. */
-#ifndef _BPF_CRYPTO_H
-#define _BPF_CRYPTO_H
-
-struct bpf_crypto_type {
-	void *(*alloc_tfm)(const char *algo);
-	void (*free_tfm)(void *tfm);
-	int (*has_algo)(const char *algo);
-	int (*setkey)(void *tfm, const u8 *key, unsigned int keylen);
-	int (*setauthsize)(void *tfm, unsigned int authsize);
-	int (*encrypt)(void *tfm, const u8 *src, u8 *dst, unsigned int len, u8 *iv);
-	int (*decrypt)(void *tfm, const u8 *src, u8 *dst, unsigned int len, u8 *iv);
-	unsigned int (*ivsize)(void *tfm);
-	unsigned int (*statesize)(void *tfm);
-	u32 (*get_flags)(void *tfm);
-	struct module *owner;
-	char name[14];
-};
-
-int bpf_crypto_register_type(const struct bpf_crypto_type *type);
-int bpf_crypto_unregister_type(const struct bpf_crypto_type *type);
-
-#endif /* _BPF_CRYPTO_H */