From 6b7f9397c98c72902f9364056413c73fe6dee1d8 Mon Sep 17 00:00:00 2001 From: Lukas Wunner Date: Mon, 7 Apr 2025 21:32:42 +0200 Subject: crypto: ecdsa - Fix NIST P521 key size reported by KEYCTL_PKEY_QUERY When user space issues a KEYCTL_PKEY_QUERY system call for a NIST P521 key, the key_size is incorrectly reported as 528 bits instead of 521. That's because the key size obtained through crypto_sig_keysize() is in bytes and software_key_query() multiplies by 8 to yield the size in bits. The underlying assumption is that the key size is always a multiple of 8. With the recent addition of NIST P521, that's no longer the case. Fix by returning the key_size in bits from crypto_sig_keysize() and adjusting the calculations in software_key_query(). The ->key_size() callbacks of sig_alg algorithms now return the size in bits, whereas the ->digest_size() and ->max_size() callbacks return the size in bytes. This matches with the units in struct keyctl_pkey_query. Fixes: a7d45ba77d3d ("crypto: ecdsa - Register NIST P521 and extend test suite") Signed-off-by: Lukas Wunner Reviewed-by: Stefan Berger Reviewed-by: Ignat Korchagin Signed-off-by: Herbert Xu --- crypto/sig.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) (limited to 'crypto/sig.c') diff --git a/crypto/sig.c b/crypto/sig.c index dfc7cae90802..53a3dd6fbe3f 100644 --- a/crypto/sig.c +++ b/crypto/sig.c @@ -102,6 +102,11 @@ static int sig_default_set_key(struct crypto_sig *tfm, return -ENOSYS; } +static unsigned int sig_default_size(struct crypto_sig *tfm) +{ + return DIV_ROUND_UP_POW2(crypto_sig_keysize(tfm), BITS_PER_BYTE); +} + static int sig_prepare_alg(struct sig_alg *alg) { struct crypto_alg *base = &alg->base; @@ -117,9 +122,9 @@ static int sig_prepare_alg(struct sig_alg *alg) if (!alg->key_size) return -EINVAL; if (!alg->max_size) - alg->max_size = alg->key_size; + alg->max_size = sig_default_size; if (!alg->digest_size) - alg->digest_size = alg->key_size; + alg->digest_size = sig_default_size; base->cra_type = &crypto_sig_type; base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK; -- cgit v1.2.3