2021-11-16 00:19:48

by Eric Snowberg

Subject: [PATCH v7 04/17] X.509: Parse Basic Constraints for CA

Parse the X.509 Basic Constraints. The basic constraints extension
identifies whether the subject of the certificate is a CA.

BasicConstraints ::= SEQUENCE {
cA BOOLEAN DEFAULT FALSE,
pathLenConstraint INTEGER (0..MAX) OPTIONAL }

If the CA is true, store it in a new public_key field call key_is_ca.
This will be used in a follow on patch that requires knowing if the
public key is a CA.

Signed-off-by: Eric Snowberg <[email protected]>
---
v7: Initial version
---
crypto/asymmetric_keys/x509_cert_parser.c | 9 +++++++++
include/crypto/public_key.h | 1 +
2 files changed, 10 insertions(+)

diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c
index 6d003096b5bc..f4299b8a4926 100644
--- a/crypto/asymmetric_keys/x509_cert_parser.c
+++ b/crypto/asymmetric_keys/x509_cert_parser.c
@@ -571,6 +571,15 @@ int x509_process_extension(void *context, size_t hdrlen,
return 0;
}

+ if (ctx->last_oid == OID_basicConstraints) {
+ if (v[0] != (ASN1_CONS_BIT | ASN1_SEQ))
+ return -EBADMSG;
+ if (v[1] != vlen - 2)
+ return -EBADMSG;
+ if (v[1] != 0 && v[2] == ASN1_BOOL && v[3] == 1)
+ ctx->cert->pub->key_is_ca = true;
+ }
+
return 0;
}

diff --git a/include/crypto/public_key.h b/include/crypto/public_key.h
index a9b2e600b7cc..61c66be80995 100644
--- a/include/crypto/public_key.h
+++ b/include/crypto/public_key.h
@@ -28,6 +28,7 @@ struct public_key {
bool key_is_private;
const char *id_type;
const char *pkey_algo;
+ bool key_is_ca;
};

extern void public_key_free(struct public_key *key);
--
2.18.4

2021-11-18 23:00:33

by Mimi Zohar

Subject: Re: [PATCH v7 04/17] X.509: Parse Basic Constraints for CA

Hi Eric,

On Mon, 2021-11-15 at 19:15 -0500, Eric Snowberg wrote:
> Parse the X.509 Basic Constraints. The basic constraints extension
> identifies whether the subject of the certificate is a CA.
>
> BasicConstraints ::= SEQUENCE {
> cA BOOLEAN DEFAULT FALSE,
> pathLenConstraint INTEGER (0..MAX) OPTIONAL }
>
> If the CA is true, store it in a new public_key field call key_is_ca.
> This will be used in a follow on patch that requires knowing if the
> public key is a CA.
>
> Signed-off-by: Eric Snowberg <[email protected]>
> ---
> v7: Initial version
> ---
> crypto/asymmetric_keys/x509_cert_parser.c | 9 +++++++++
> include/crypto/public_key.h | 1 +
> 2 files changed, 10 insertions(+)
>
> diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c
> index 6d003096b5bc..f4299b8a4926 100644
> --- a/crypto/asymmetric_keys/x509_cert_parser.c
> +++ b/crypto/asymmetric_keys/x509_cert_parser.c
> @@ -571,6 +571,15 @@ int x509_process_extension(void *context, size_t hdrlen,
> return 0;
> }
>
> + if (ctx->last_oid == OID_basicConstraints) {
> + if (v[0] != (ASN1_CONS_BIT | ASN1_SEQ))
> + return -EBADMSG;
> + if (v[1] != vlen - 2)
> + return -EBADMSG;
> + if (v[1] != 0 && v[2] == ASN1_BOOL && v[3] == 1)
> + ctx->cert->pub->key_is_ca = true;
> + }
> +
> return 0;
> }
>
> diff --git a/include/crypto/public_key.h b/include/crypto/public_key.h
> index a9b2e600b7cc..61c66be80995 100644
> --- a/include/crypto/public_key.h
> +++ b/include/crypto/public_key.h
> @@ -28,6 +28,7 @@ struct public_key {
> bool key_is_private;
> const char *id_type;
> const char *pkey_algo;
> + bool key_is_ca;

David added "key_is_private" intentionally where he did. Adding the
"key_is_ca" immediately afterwards doesn't change the struct size.

Mimi

> };
>
> extern void public_key_free(struct public_key *key);

2021-11-18 23:30:13

by Eric Snowberg

Subject: Re: [PATCH v7 04/17] X.509: Parse Basic Constraints for CA

> On Nov 18, 2021, at 3:59 PM, Mimi Zohar <[email protected]> wrote:
>
> Hi Eric,
>
> On Mon, 2021-11-15 at 19:15 -0500, Eric Snowberg wrote:
>> Parse the X.509 Basic Constraints. The basic constraints extension
>> identifies whether the subject of the certificate is a CA.
>>
>> BasicConstraints ::= SEQUENCE {
>> cA BOOLEAN DEFAULT FALSE,
>> pathLenConstraint INTEGER (0..MAX) OPTIONAL }
>>
>> If the CA is true, store it in a new public_key field call key_is_ca.
>> This will be used in a follow on patch that requires knowing if the
>> public key is a CA.
>>
>> Signed-off-by: Eric Snowberg <[email protected]>
>> ---
>> v7: Initial version
>> ---
>> crypto/asymmetric_keys/x509_cert_parser.c | 9 +++++++++
>> include/crypto/public_key.h | 1 +
>> 2 files changed, 10 insertions(+)
>>
>> diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c
>> index 6d003096b5bc..f4299b8a4926 100644
>> --- a/crypto/asymmetric_keys/x509_cert_parser.c
>> +++ b/crypto/asymmetric_keys/x509_cert_parser.c
>> @@ -571,6 +571,15 @@ int x509_process_extension(void *context, size_t hdrlen,
>> return 0;
>> }
>>
>> + if (ctx->last_oid == OID_basicConstraints) {
>> + if (v[0] != (ASN1_CONS_BIT | ASN1_SEQ))
>> + return -EBADMSG;
>> + if (v[1] != vlen - 2)
>> + return -EBADMSG;
>> + if (v[1] != 0 && v[2] == ASN1_BOOL && v[3] == 1)
>> + ctx->cert->pub->key_is_ca = true;
>> + }
>> +
>> return 0;
>> }
>>
>> diff --git a/include/crypto/public_key.h b/include/crypto/public_key.h
>> index a9b2e600b7cc..61c66be80995 100644
>> --- a/include/crypto/public_key.h
>> +++ b/include/crypto/public_key.h
>> @@ -28,6 +28,7 @@ struct public_key {
>> bool key_is_private;
>> const char *id_type;
>> const char *pkey_algo;
>> + bool key_is_ca;
>
> David added "key_is_private" intentionally where he did. Adding the
> "key_is_ca" immediately afterwards doesn't change the struct size.

Ok, I’ll change that in the next round. Thanks.