| Message ID | 20220715182810.30505-1-denkenz@gmail.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Delegated to: | Herbert Xu |
| Headers | show |
| Series | KEYS: asymmetric: Fix ECDSA use via keyctl uapi | expand |
On 7/15/22 14:28, Denis Kenzior wrote: > When support for ECDSA keys was added, constraints for data & signature > sizes were never updated. This makes it impossible to use such keys via > keyctl API from userspace; fix that. > > Fixes: 299f561a6693 ("x509: Add support for parsing x509 certs with ECDSA keys") > Signed-off-by: Denis Kenzior <denkenz@gmail.com> > --- > crypto/asymmetric_keys/public_key.c | 24 ++++++++++++++++++++++-- > 1 file changed, 22 insertions(+), 2 deletions(-) > > diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c > index 2f8352e88860..eca5671ad3f2 100644 > --- a/crypto/asymmetric_keys/public_key.c > +++ b/crypto/asymmetric_keys/public_key.c > @@ -186,8 +186,28 @@ static int software_key_query(const struct kernel_pkey_params *params, > > len = crypto_akcipher_maxsize(tfm); > info->key_size = len * 8; > - info->max_data_size = len; > - info->max_sig_size = len; > + > + if (strncmp(pkey->pkey_algo, "ecdsa", 5) == 0) { > + /* > + * ECDSA key sizes are much smaller than RSA, and thus could > + * operate on (hashed) inputs that are larger than key size. > + * For example SHA384-hashed input used with secp256r1 > + * based keys. Set max_data_size to be at least as large as > + * the largest supported hash size (SHA512) > + */ > + info->max_data_size = 64; > + > + /* > + * Verify takes ECDSA-Sig (described in RFC 5480) as input, > + * which is actually 2 'key_size'-bit integers encoded in > + * ASN.1. Account for the ASN.1 encoding overhead here. > + */ > + info->max_sig_size = 2 * (len + 3) + 2; This part matches what I wrote about here: https://lore.kernel.org/linux-integrity/127811ae-ef71-d225-0450-710a6ee6afef@linux.ibm.com/T/#m7aea8ca697e7c35773c3f8f110329553f4f8d91e Reviewed-by: Stefan Berger <stefanb@linux.ibm.com> > + } else { > + info->max_data_size = len; > + info->max_sig_size = len; > + } > + > info->max_enc_size = len; > info->max_dec_size = len; > info->supported_ops = (KEYCTL_SUPPORTS_ENCRYPT |
diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c index 2f8352e88860..eca5671ad3f2 100644 --- a/crypto/asymmetric_keys/public_key.c +++ b/crypto/asymmetric_keys/public_key.c @@ -186,8 +186,28 @@ static int software_key_query(const struct kernel_pkey_params *params, len = crypto_akcipher_maxsize(tfm); info->key_size = len * 8; - info->max_data_size = len; - info->max_sig_size = len; + + if (strncmp(pkey->pkey_algo, "ecdsa", 5) == 0) { + /* + * ECDSA key sizes are much smaller than RSA, and thus could + * operate on (hashed) inputs that are larger than key size. + * For example SHA384-hashed input used with secp256r1 + * based keys. Set max_data_size to be at least as large as + * the largest supported hash size (SHA512) + */ + info->max_data_size = 64; + + /* + * Verify takes ECDSA-Sig (described in RFC 5480) as input, + * which is actually 2 'key_size'-bit integers encoded in + * ASN.1. Account for the ASN.1 encoding overhead here. + */ + info->max_sig_size = 2 * (len + 3) + 2; + } else { + info->max_data_size = len; + info->max_sig_size = len; + } + info->max_enc_size = len; info->max_dec_size = len; info->supported_ops = (KEYCTL_SUPPORTS_ENCRYPT |
When support for ECDSA keys was added, constraints for data & signature sizes were never updated. This makes it impossible to use such keys via keyctl API from userspace; fix that. Fixes: 299f561a6693 ("x509: Add support for parsing x509 certs with ECDSA keys") Signed-off-by: Denis Kenzior <denkenz@gmail.com> --- crypto/asymmetric_keys/public_key.c | 24 ++++++++++++++++++++++-- 1 file changed, 22 insertions(+), 2 deletions(-)