From: Stefan Berger <[email protected]>
This series of patches adds support for x509 certificates signed by a CA
that uses NIST p256 or p192 keys for signing. It also adds support for
certificates where the public key is a NIST p256 or p192 key. The math
for ECDSA signature verification is also added.
Since self-signed certificates are verified upon loading, the following
script can be used for testing:
k=$(keyctrl newring test @u)
while :; do
for hash in sha1 sha224 sha256 sha384 sha512; do
openssl req \
-x509 \
-${hash} \
-newkey ec \
-pkeyopt ec_paramgen_curve:prime256v1 \
-keyout key.pem \
-days 365 \
-subj '/CN=test' \
-nodes \
-outform der \
-out cert.der
keyctl padd asymmetric testkey $k < cert.der
if [ $? -ne 0 ]; then
echo "ERROR"
exit 1
fi
done
done
It also works with restricted keyrings where an RSA key is used to sign
a NIST P256/P192 key. Scripts for testing are here:
https://github.com/stefanberger/eckey-testing
The ECDSA signature verification will be used by IMA Appraisal where ECDSA
file signatures stored in RPM packages will use substantially less space
than if RSA signatures were to be used.
Stefan
v2->v3:
- patch 2 now includes linux/scatterlist.h
v1->v2:
- using faster vli_sub rather than newly added vli_mod_fast to 'reduce'
result
- rearranged switch statements to follow after RSA
- 3rd patch from 1st posting is now 1st patch
Stefan Berger (3):
x509: Detect sm2 keys by their parameters OID
x509: Add support for parsing x509 certs with NIST p256 keys
x509: Add support for NIST p192 keys in certificates and akcipher
crypto/Makefile | 9 +-
crypto/asymmetric_keys/public_key.c | 19 ++
crypto/asymmetric_keys/x509_cert_parser.c | 45 ++-
crypto/ecc.c | 318 ++++++++++++++++++++++
crypto/ecc.h | 2 +
crypto/ecc_curve_defs.h | 4 +
crypto/eccsignature.asn1 | 4 +
include/linux/oid_registry.h | 6 +
8 files changed, 404 insertions(+), 3 deletions(-)
create mode 100644 crypto/eccsignature.asn1
--
2.25.4
From: Stefan Berger <[email protected]>
Add support for NIST p192 keys in x509 certificates and support it in
'akcipher'.
Signed-off-by: Stefan Berger <[email protected]>
---
crypto/asymmetric_keys/public_key.c | 3 ++
crypto/asymmetric_keys/x509_cert_parser.c | 1 +
crypto/ecc.c | 36 ++++++++++++++++++++++-
include/linux/oid_registry.h | 1 +
4 files changed, 40 insertions(+), 1 deletion(-)
diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c
index 0fcbaec0ded0..bb4a7cc0e3c8 100644
--- a/crypto/asymmetric_keys/public_key.c
+++ b/crypto/asymmetric_keys/public_key.c
@@ -98,6 +98,9 @@ int software_key_determine_akcipher(const char *encoding,
oid = look_up_OID(pkey->params + 2, pkey->paramlen - 2);
switch (oid) {
+ case OID_id_prime192v1:
+ strcpy(alg_name, "nist_p192");
+ return 0;
case OID_id_prime256v1:
strcpy(alg_name, "nist_p256");
return 0;
diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c
index 50f6ecc70d8b..5ff891f8235d 100644
--- a/crypto/asymmetric_keys/x509_cert_parser.c
+++ b/crypto/asymmetric_keys/x509_cert_parser.c
@@ -505,6 +505,7 @@ int x509_extract_key_data(void *context, size_t hdrlen,
case OID_sm2:
ctx->cert->pub->pkey_algo = "sm2";
break;
+ case OID_id_prime192v1:
case OID_id_prime256v1:
ctx->cert->pub->pkey_algo = "ecdsa";
break;
diff --git a/crypto/ecc.c b/crypto/ecc.c
index 98577ed99aaf..0690c37f74e3 100644
--- a/crypto/ecc.c
+++ b/crypto/ecc.c
@@ -1813,13 +1813,47 @@ static struct akcipher_alg ecc_nist_p256 = {
},
};
+static unsigned int ecc_nist_p192_max_size(struct crypto_akcipher *tfm)
+{
+ return NIST_P192_KEY_SIZE;
+}
+
+static int ecc_nist_p192_init_tfm(struct crypto_akcipher *tfm)
+{
+ struct ecc_ctx *ctx = akcipher_tfm_ctx(tfm);
+
+ return ecc_ec_ctx_init(ctx, ECC_CURVE_NIST_P192);
+}
+
+static struct akcipher_alg ecc_nist_p192 = {
+ .verify = ecdsa_verify,
+ .set_pub_key = ecc_set_pub_key,
+ .max_size = ecc_nist_p192_max_size,
+ .init = ecc_nist_p192_init_tfm,
+ .exit = ecc_exit_tfm,
+ .base = {
+ .cra_name = "nist_p192",
+ .cra_driver_name = "ecc-nist-p192",
+ .cra_priority = 100,
+ .cra_module = THIS_MODULE,
+ .cra_ctxsize = sizeof(struct ecc_ctx),
+ },
+};
+
static int ecc_init(void)
{
- return crypto_register_akcipher(&ecc_nist_p256);
+ int ret;
+
+ ret = crypto_register_akcipher(&ecc_nist_p256);
+ if (ret)
+ return ret;
+
+ return crypto_register_akcipher(&ecc_nist_p192);
}
static void ecc_exit(void)
{
+ crypto_unregister_akcipher(&ecc_nist_p192);
crypto_unregister_akcipher(&ecc_nist_p256);
}
diff --git a/include/linux/oid_registry.h b/include/linux/oid_registry.h
index 9060f19c80eb..e8071133d0e2 100644
--- a/include/linux/oid_registry.h
+++ b/include/linux/oid_registry.h
@@ -21,6 +21,7 @@ enum OID {
OID_id_dsa, /* 1.2.840.10040.4.1 */
OID_id_ecdsa_with_sha1, /* 1.2.840.10045.4.1 */
OID_id_ecPublicKey, /* 1.2.840.10045.2.1 */
+ OID_id_prime192v1, /* 1.2.840.10045.3.1.1 */
OID_id_prime256v1, /* 1.2.840.10045.3.1.7 */
OID_id_ecdsa_with_sha224, /* 1.2.840.10045.4.3.1 */
OID_id_ecdsa_with_sha256, /* 1.2.840.10045.4.3.2 */
--
2.25.4
From: Stefan Berger <[email protected]>
Detect whether a key is an sm2 type of key by its OID in the parameters
array rather than assuming that everything under OID_id_ecPublicKey
is sm2, which is not the case.
Signed-off-by: Stefan Berger <[email protected]>
---
crypto/asymmetric_keys/x509_cert_parser.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c
index 52c9b455fc7d..4643fe5ed69a 100644
--- a/crypto/asymmetric_keys/x509_cert_parser.c
+++ b/crypto/asymmetric_keys/x509_cert_parser.c
@@ -459,6 +459,7 @@ int x509_extract_key_data(void *context, size_t hdrlen,
const void *value, size_t vlen)
{
struct x509_parse_context *ctx = context;
+ enum OID oid;
ctx->key_algo = ctx->last_oid;
switch (ctx->last_oid) {
@@ -470,7 +471,17 @@ int x509_extract_key_data(void *context, size_t hdrlen,
ctx->cert->pub->pkey_algo = "ecrdsa";
break;
case OID_id_ecPublicKey:
- ctx->cert->pub->pkey_algo = "sm2";
+ if (ctx->params_size < 2)
+ return -ENOPKG;
+
+ oid = look_up_OID(ctx->params + 2, ctx->params_size - 2);
+ switch (oid) {
+ case OID_sm2:
+ ctx->cert->pub->pkey_algo = "sm2";
+ break;
+ default:
+ return -ENOPKG;
+ }
break;
default:
return -ENOPKG;
--
2.25.4
Stefan Berger <[email protected]> wrote:
> k=$(keyctrl newring test @u)
keyctl - but I can fix that.
David
Stefan Berger <[email protected]> wrote:
> This series of patches adds support for x509 certificates signed by a CA
> that uses NIST p256 or p192 keys for signing. It also adds support for
> certificates where the public key is a NIST p256 or p192 key. The math
> for ECDSA signature verification is also added.
>
> Since self-signed certificates are verified upon loading, the following
> script can be used for testing:
>
> k=$(keyctrl newring test @u)
>
> while :; do
> for hash in sha1 sha224 sha256 sha384 sha512; do
> openssl req \
> -x509 \
> -${hash} \
> -newkey ec \
> -pkeyopt ec_paramgen_curve:prime256v1 \
> -keyout key.pem \
> -days 365 \
> -subj '/CN=test' \
> -nodes \
> -outform der \
> -out cert.der
> keyctl padd asymmetric testkey $k < cert.der
> if [ $? -ne 0 ]; then
> echo "ERROR"
> exit 1
> fi
> done
> done
>
> It also works with restricted keyrings where an RSA key is used to sign
> a NIST P256/P192 key. Scripts for testing are here:
>
> https://github.com/stefanberger/eckey-testing
>
> The ECDSA signature verification will be used by IMA Appraisal where ECDSA
> file signatures stored in RPM packages will use substantially less space
> than if RSA signatures were to be used.
I've pulled this into my keys-next branch.
David
Hi Stefan,
In the recommendations from SafeCurves (https://safecurves.cr.yp.to/twist.html) there are a number of attacks against ECC twists. Two of those attacks are relevant against NIST P192: invalid-curve attacks and invalid-curve attacks against ladders.
Both attacks can be mitigated by checking the supplied public key is on the correct curve, before performing curve operations.
Not sure if the right place for those checks are in the signature verification code provided in these patches, or when reading public keys from the certificates. Does the kernel provide functions for checking curve points satisfy their respective curve equations?
There are also tables describing the cost of combined attacks on various curves, where NIST P224 already falls below the safe threshold. Because of that, I would recommend not implementing support for NIST P192 (since it would fair even worse).
What are your thoughts?
Best,
Nym
‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Wednesday, January 27, 2021 12:33 PM, Stefan Berger <[email protected]> wrote:
> From: Stefan Berger [email protected]
>
> This series of patches adds support for x509 certificates signed by a CA
> that uses NIST p256 or p192 keys for signing. It also adds support for
> certificates where the public key is a NIST p256 or p192 key. The math
> for ECDSA signature verification is also added.
>
> Since self-signed certificates are verified upon loading, the following
> script can be used for testing:
>
> k=$(keyctrl newring test @u)
>
> while :; do
> for hash in sha1 sha224 sha256 sha384 sha512; do
> openssl req \
> -x509 \
> -${hash} \
> -newkey ec \
> -pkeyopt ec_paramgen_curve:prime256v1 \
> -keyout key.pem \
> -days 365 \
> -subj '/CN=test' \
> -nodes \
> -outform der \
> -out cert.der
> keyctl padd asymmetric testkey $k < cert.der
> if [ $? -ne 0 ]; then
> echo "ERROR"
> exit 1
> fi
> done
> done
>
> It also works with restricted keyrings where an RSA key is used to sign
> a NIST P256/P192 key. Scripts for testing are here:
>
> https://github.com/stefanberger/eckey-testing
>
> The ECDSA signature verification will be used by IMA Appraisal where ECDSA
> file signatures stored in RPM packages will use substantially less space
> than if RSA signatures were to be used.
>
> Stefan
>
> v2->v3:
>
> - patch 2 now includes linux/scatterlist.h
>
> v1->v2:
>
> - using faster vli_sub rather than newly added vli_mod_fast to 'reduce'
> result
>
> - rearranged switch statements to follow after RSA
>
> - 3rd patch from 1st posting is now 1st patch
>
> Stefan Berger (3):
> x509: Detect sm2 keys by their parameters OID
> x509: Add support for parsing x509 certs with NIST p256 keys
> x509: Add support for NIST p192 keys in certificates and akcipher
>
> crypto/Makefile | 9 +-
> crypto/asymmetric_keys/public_key.c | 19 ++
> crypto/asymmetric_keys/x509_cert_parser.c | 45 ++-
> crypto/ecc.c | 318 ++++++++++++++++++++++
> crypto/ecc.h | 2 +
> crypto/ecc_curve_defs.h | 4 +
> crypto/eccsignature.asn1 | 4 +
> include/linux/oid_registry.h | 6 +
> 8 files changed, 404 insertions(+), 3 deletions(-)
> create mode 100644 crypto/eccsignature.asn1
>
> --
> 2.25.4
>
On Wed, Jan 27, 2021 at 02:22:08PM +0000, David Howells wrote:
>
> I've pulled this into my keys-next branch.
David, please drop them because there are issues with the Crypto API
bits.
Thanks,
--
Email: Herbert Xu <[email protected]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
Herbert Xu <[email protected]> wrote:
> > I've pulled this into my keys-next branch.
>
> David, please drop them because there are issues with the Crypto API
> bits.
Okay, dropped.
David
On 1/27/21 11:12 AM, Nym Seddon wrote:
> Hi Stefan,
>
> In the recommendations from SafeCurves (https://safecurves.cr.yp.to/twist.html) there are a number of attacks against ECC twists. Two of those attacks are relevant against NIST P192: invalid-curve attacks and invalid-curve attacks against ladders.
>
> Both attacks can be mitigated by checking the supplied public key is on the correct curve, before performing curve operations.
>
> Not sure if the right place for those checks are in the signature verification code provided in these patches, or when reading public keys from the certificates. Does the kernel provide functions for checking curve points satisfy their respective curve equations?
>
> There are also tables describing the cost of combined attacks on various curves, where NIST P224 already falls below the safe threshold. Because of that, I would recommend not implementing support for NIST P192 (since it would fair even worse).
>
> What are your thoughts?
I am calling into a function performing such a test at the end of the
function parsing the public key:
return ecc_is_pubkey_valid_full(ctx->curve, ctx->pub_key)
https://elixir.bootlin.com/linux/latest/source/crypto/ecc.c#L1458
Is that good 'enough' ?
Stefan
On Wed, 2021-01-27 at 07:33 -0500, Stefan Berger wrote:
> From: Stefan Berger <[email protected]>
>
> Detect whether a key is an sm2 type of key by its OID in the parameters
> array rather than assuming that everything under OID_id_ecPublicKey
> is sm2, which is not the case.
>
> Signed-off-by: Stefan Berger <[email protected]>
> ---
> crypto/asymmetric_keys/x509_cert_parser.c | 13 ++++++++++++-
> 1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c
> index 52c9b455fc7d..4643fe5ed69a 100644
> --- a/crypto/asymmetric_keys/x509_cert_parser.c
> +++ b/crypto/asymmetric_keys/x509_cert_parser.c
> @@ -459,6 +459,7 @@ int x509_extract_key_data(void *context, size_t hdrlen,
> const void *value, size_t vlen)
> {
> struct x509_parse_context *ctx = context;
> + enum OID oid;
>
> ctx->key_algo = ctx->last_oid;
> switch (ctx->last_oid) {
> @@ -470,7 +471,17 @@ int x509_extract_key_data(void *context, size_t hdrlen,
> ctx->cert->pub->pkey_algo = "ecrdsa";
> break;
> case OID_id_ecPublicKey:
> - ctx->cert->pub->pkey_algo = "sm2";
> + if (ctx->params_size < 2)
Either a named constant, or at least a comment instead of just '2'.
> + return -ENOPKG;
> +
> + oid = look_up_OID(ctx->params + 2, ctx->params_size - 2);
> + switch (oid) {
> + case OID_sm2:
> + ctx->cert->pub->pkey_algo = "sm2";
> + break;
> + default:
> + return -ENOPKG;
> + }
> break;
> default:
> return -ENOPKG;
/Jarkko
On Sat, Jan 30, 2021 at 09:57:40PM -0500, Stefan Berger wrote:
> On 1/30/21 4:26 PM, Jarkko Sakkinen wrote:
> > On Wed, 2021-01-27 at 07:33 -0500, Stefan Berger wrote:
> > > From: Stefan Berger <[email protected]>
> > >
> > > Detect whether a key is an sm2 type of key by its OID in the parameters
> > > array rather than assuming that everything under OID_id_ecPublicKey
> > > is sm2, which is not the case.
> > >
> > > Signed-off-by: Stefan Berger <[email protected]>
> > > ---
> > > ?crypto/asymmetric_keys/x509_cert_parser.c | 13 ++++++++++++-
> > > ?1 file changed, 12 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c
> > > index 52c9b455fc7d..4643fe5ed69a 100644
> > > --- a/crypto/asymmetric_keys/x509_cert_parser.c
> > > +++ b/crypto/asymmetric_keys/x509_cert_parser.c
> > > @@ -459,6 +459,7 @@ int x509_extract_key_data(void *context, size_t hdrlen,
> > > ????????????????????????? const void *value, size_t vlen)
> > > ?{
> > > ????????struct x509_parse_context *ctx = context;
> > > +???????enum OID oid;
> > > ????????ctx->key_algo = ctx->last_oid;
> > > ????????switch (ctx->last_oid) {
> > > @@ -470,7 +471,17 @@ int x509_extract_key_data(void *context, size_t hdrlen,
> > > ????????????????ctx->cert->pub->pkey_algo = "ecrdsa";
> > > ????????????????break;
> > > ????????case OID_id_ecPublicKey:
> > > -???????????????ctx->cert->pub->pkey_algo = "sm2";
> > > +???????????????if (ctx->params_size < 2)
> > Either a named constant, or at least a comment instead of just '2'.
>
>
> I will look at the 2 entries whether they contain the expected values:
> ASN1_OID and length
>
> Thanks!
>
> ?? Stefan
Just add inline comment that explains that.
/Jarkko