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[v2] crypto: lib/chachapoly - Drop dependency on CRYPTO_ALGAPI

Message ID 20250228121137.3534964-2-ardb+git@google.com
State New
Headers show
Series [v2] crypto: lib/chachapoly - Drop dependency on CRYPTO_ALGAPI | expand

Commit Message

Ard Biesheuvel Feb. 28, 2025, 12:11 p.m. UTC 
From: Ard Biesheuvel <ardb@kernel.org>

The ChaCha20-Poly1305 library code uses the sg_miter API to process
input presented via scatterlists, except for the special case where the
digest buffer is not covered entirely by the same scatterlist entry as
the last byte of input. In that case, it uses scatterwalk_map_and_copy()
to access the memory in the input scatterlist where the digest is stored.

This results in a dependency on crypto/scatterwalk.c and therefore on
CONFIG_CRYPTO_ALGAPI, which is unnecessary, as the sg_miter API already
provides this functionality via sg_copy_to_buffer(). So use that
instead, and drop the dependencies on CONFIG_CRYPTO_ALGAPI and
CONFIG_CRYPTO.

Reported-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
v2: - replace include of crypto/algapi.h with crypto/utils.h
    - drop dependency on CONFIG_CRYPTO

 lib/crypto/Kconfig            | 2 --
 lib/crypto/chacha20poly1305.c | 7 +++----
 2 files changed, 3 insertions(+), 6 deletions(-)
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Patch

diff --git a/lib/crypto/Kconfig b/lib/crypto/Kconfig
index c542ef1d64d0..562906be4f93 100644
--- a/lib/crypto/Kconfig
+++ b/lib/crypto/Kconfig
@@ -142,10 +142,8 @@  config CRYPTO_LIB_POLY1305
 
 config CRYPTO_LIB_CHACHA20POLY1305
 	tristate "ChaCha20-Poly1305 AEAD support (8-byte nonce library version)"
-	depends on CRYPTO
 	select CRYPTO_LIB_CHACHA
 	select CRYPTO_LIB_POLY1305
-	select CRYPTO_ALGAPI
 
 config CRYPTO_LIB_SHA1
 	tristate
diff --git a/lib/crypto/chacha20poly1305.c b/lib/crypto/chacha20poly1305.c
index a839c0ac60b2..9cfa886f1f89 100644
--- a/lib/crypto/chacha20poly1305.c
+++ b/lib/crypto/chacha20poly1305.c
@@ -7,11 +7,10 @@ 
  * Information: https://tools.ietf.org/html/rfc8439
  */
 
-#include <crypto/algapi.h>
 #include <crypto/chacha20poly1305.h>
 #include <crypto/chacha.h>
 #include <crypto/poly1305.h>
-#include <crypto/scatterwalk.h>
+#include <crypto/utils.h>
 
 #include <linux/unaligned.h>
 #include <linux/kernel.h>
@@ -318,8 +317,8 @@  bool chacha20poly1305_crypt_sg_inplace(struct scatterlist *src,
 
 	if (unlikely(sl > -POLY1305_DIGEST_SIZE)) {
 		poly1305_final(&poly1305_state, b.mac[1]);
-		scatterwalk_map_and_copy(b.mac[encrypt], src, src_len,
-					 sizeof(b.mac[1]), encrypt);
+		sg_copy_buffer(src, sg_nents(src), b.mac[encrypt],
+			       sizeof(b.mac[1]), src_len, !encrypt);
 		ret = encrypt ||
 		      !crypto_memneq(b.mac[0], b.mac[1], POLY1305_DIGEST_SIZE);
 	}