| Message ID | 20220301173651.3435350-3-eric.snowberg@oracle.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Add CA enforcement in the machine keyring | expand |
On 3/1/22 12:36, 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 <eric.snowberg@oracle.com> > --- > 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 2899ed80bb18..38c907f4ce27 100644 > --- a/crypto/asymmetric_keys/x509_cert_parser.c > +++ b/crypto/asymmetric_keys/x509_cert_parser.c > @@ -583,6 +583,15 @@ int x509_process_extension(void *context, size_t hdrlen, > return 0; > } > > + if (ctx->last_oid == OID_basicConstraints) { Don't you have to check whether you can access v[0] and v[1]? if (vlen < 3) return -EBADMSG; or should it even be if (vlen != 3) return -EBADMSG; > + 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 6d61695e1cde..0521241764b7 100644 > --- a/include/crypto/public_key.h > +++ b/include/crypto/public_key.h > @@ -26,6 +26,7 @@ struct public_key { > void *params; > u32 paramlen; > bool key_is_private; > + bool key_is_ca; > const char *id_type; > const char *pkey_algo; > };
> On Mar 4, 2022, at 8:10 AM, Stefan Berger <stefanb@linux.ibm.com> wrote: > > > On 3/1/22 12:36, 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 <eric.snowberg@oracle.com> >> --- >> 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 2899ed80bb18..38c907f4ce27 100644 >> --- a/crypto/asymmetric_keys/x509_cert_parser.c >> +++ b/crypto/asymmetric_keys/x509_cert_parser.c >> @@ -583,6 +583,15 @@ int x509_process_extension(void *context, size_t hdrlen, >> return 0; >> } >> + if (ctx->last_oid == OID_basicConstraints) { > > Don't you have to check whether you can access v[0] and v[1]? Good catch, I’ll add the check > if (vlen < 3) > > return -EBADMSG; I think this would be best > or should it even be > > if (vlen != 3) > > return -EBADMSG; since the length could be larger than 3 if the optional pathLenConstraint is supplied.
diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c index 2899ed80bb18..38c907f4ce27 100644 --- a/crypto/asymmetric_keys/x509_cert_parser.c +++ b/crypto/asymmetric_keys/x509_cert_parser.c @@ -583,6 +583,15 @@ 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 6d61695e1cde..0521241764b7 100644 --- a/include/crypto/public_key.h +++ b/include/crypto/public_key.h @@ -26,6 +26,7 @@ struct public_key { void *params; u32 paramlen; bool key_is_private; + bool key_is_ca; const char *id_type; const char *pkey_algo; };
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 <eric.snowberg@oracle.com> --- crypto/asymmetric_keys/x509_cert_parser.c | 9 +++++++++ include/crypto/public_key.h | 1 + 2 files changed, 10 insertions(+)