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Subject[PATCH 2/5] crypto: chacha20 - Use unaligned access macros when loading key and IV
Date
From: Eric Biggers <ebiggers@google.com>

The generic ChaCha20 implementation has a cra_alignmask of 3, which
ensures that the key passed into crypto_chacha20_setkey() and the IV
passed into crypto_chacha20_init() are 4-byte aligned. However, these
functions are also called from the ARM and ARM64 implementations of
ChaCha20, which intentionally do not have a cra_alignmask set. This is
broken because 32-bit words are being loaded from potentially-unaligned
buffers without the unaligned access macros.

Fix it by using the unaligned access macros when loading the key and IV.

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
crypto/chacha20_generic.c | 16 ++++++----------
1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/crypto/chacha20_generic.c b/crypto/chacha20_generic.c
index ec84e7837aac..b5a10ebf1b82 100644
--- a/crypto/chacha20_generic.c
+++ b/crypto/chacha20_generic.c
@@ -9,16 +9,12 @@
* (at your option) any later version.
*/

+#include <asm/unaligned.h>
#include <crypto/algapi.h>
#include <crypto/chacha20.h>
#include <crypto/internal/skcipher.h>
#include <linux/module.h>

-static inline u32 le32_to_cpuvp(const void *p)
-{
- return le32_to_cpup(p);
-}
-
static void chacha20_docrypt(u32 *state, u8 *dst, const u8 *src,
unsigned int bytes)
{
@@ -53,10 +49,10 @@ void crypto_chacha20_init(u32 *state, struct chacha20_ctx *ctx, u8 *iv)
state[9] = ctx->key[5];
state[10] = ctx->key[6];
state[11] = ctx->key[7];
- state[12] = le32_to_cpuvp(iv + 0);
- state[13] = le32_to_cpuvp(iv + 4);
- state[14] = le32_to_cpuvp(iv + 8);
- state[15] = le32_to_cpuvp(iv + 12);
+ state[12] = get_unaligned_le32(iv + 0);
+ state[13] = get_unaligned_le32(iv + 4);
+ state[14] = get_unaligned_le32(iv + 8);
+ state[15] = get_unaligned_le32(iv + 12);
}
EXPORT_SYMBOL_GPL(crypto_chacha20_init);

@@ -70,7 +66,7 @@ int crypto_chacha20_setkey(struct crypto_skcipher *tfm, const u8 *key,
return -EINVAL;

for (i = 0; i < ARRAY_SIZE(ctx->key); i++)
- ctx->key[i] = le32_to_cpuvp(key + i * sizeof(u32));
+ ctx->key[i] = get_unaligned_le32(key + i * sizeof(u32));

return 0;
}
--
2.15.0.448.gf294e3d99a-goog
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