diff mbox series

[v2] crypto: ecdh - explicitly zeroize private_key

Message ID 20240328162430.28657-1-git@jvdsn.com (mailing list archive)
State Accepted
Delegated to: Herbert Xu
Headers show
Series [v2] crypto: ecdh - explicitly zeroize private_key | expand

Commit Message

Joachim Vandersmissen March 28, 2024, 4:24 p.m. UTC
private_key is overwritten with the key parameter passed in by the
caller (if present), or alternatively a newly generated private key.
However, it is possible that the caller provides a key (or the newly
generated key) which is shorter than the previous key. In that
scenario, some key material from the previous key would not be
overwritten. The easiest solution is to explicitly zeroize the entire
private_key array first.

Note that this patch slightly changes the behavior of this function:
previously, if the ecc_gen_privkey failed, the old private_key would
remain. Now, the private_key is always zeroized. This behavior is
consistent with the case where params.key is set and ecc_is_key_valid
fails.

Signed-off-by: Joachim Vandersmissen <git@jvdsn.com>
---
 crypto/ecdh.c | 2 ++
 1 file changed, 2 insertions(+)

Comments

Herbert Xu April 5, 2024, 7:57 a.m. UTC | #1
On Thu, Mar 28, 2024 at 11:24:30AM -0500, Joachim Vandersmissen wrote:
> private_key is overwritten with the key parameter passed in by the
> caller (if present), or alternatively a newly generated private key.
> However, it is possible that the caller provides a key (or the newly
> generated key) which is shorter than the previous key. In that
> scenario, some key material from the previous key would not be
> overwritten. The easiest solution is to explicitly zeroize the entire
> private_key array first.
> 
> Note that this patch slightly changes the behavior of this function:
> previously, if the ecc_gen_privkey failed, the old private_key would
> remain. Now, the private_key is always zeroized. This behavior is
> consistent with the case where params.key is set and ecc_is_key_valid
> fails.
> 
> Signed-off-by: Joachim Vandersmissen <git@jvdsn.com>
> ---
>  crypto/ecdh.c | 2 ++
>  1 file changed, 2 insertions(+)

Patch applied.  Thanks.
diff mbox series

Patch

diff --git a/crypto/ecdh.c b/crypto/ecdh.c
index 80afee3234fb..3049f147e011 100644
--- a/crypto/ecdh.c
+++ b/crypto/ecdh.c
@@ -33,6 +33,8 @@  static int ecdh_set_secret(struct crypto_kpp *tfm, const void *buf,
 	    params.key_size > sizeof(u64) * ctx->ndigits)
 		return -EINVAL;
 
+	memset(ctx->private_key, 0, sizeof(ctx->private_key));
+
 	if (!params.key || !params.key_size)
 		return ecc_gen_privkey(ctx->curve_id, ctx->ndigits,
 				       ctx->private_key);