From: Eric Snowberg <eric.snowberg@oracle.com> Date: Thu, 2 Mar 2023 16:46:49 +0000 (-0500) Subject: KEYS: X.509: Parse Basic Constraints for CA X-Git-Tag: kvm-6.4-2~169^2~24 X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=30eae2b037af54b24109dcaea21db46f6285c69b;p=users%2Fdwmw2%2Flinux.git KEYS: 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 the public_key. This will be used in a follow on patch that requires knowing if the public key is a CA. Link: https://www.rfc-editor.org/rfc/rfc5280#section-4.2.1.9 Signed-off-by: Eric Snowberg <eric.snowberg@oracle.com> Reviewed-by: Mimi Zohar <zohar@linux.ibm.com> Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org> Tested-by: Mimi Zohar <zohar@linux.ibm.com> Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org> --- diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c index 7a9b084e2043d..77547d4bd94dd 100644 --- a/crypto/asymmetric_keys/x509_cert_parser.c +++ b/crypto/asymmetric_keys/x509_cert_parser.c @@ -586,6 +586,28 @@ int x509_process_extension(void *context, size_t hdrlen, return 0; } + if (ctx->last_oid == OID_basicConstraints) { + /* + * Get hold of the basicConstraints + * v[1] is the encoding size + * (Expect 0x2 or greater, making it 1 or more bytes) + * v[2] is the encoding type + * (Expect an ASN1_BOOL for the CA) + * v[3] is the contents of the ASN1_BOOL + * (Expect 1 if the CA is TRUE) + * vlen should match the entire extension size + */ + if (v[0] != (ASN1_CONS_BIT | ASN1_SEQ)) + return -EBADMSG; + if (vlen < 2) + return -EBADMSG; + if (v[1] != vlen - 2) + return -EBADMSG; + if (vlen >= 4 && v[1] != 0 && v[2] == ASN1_BOOL && v[3] == 1) + ctx->cert->pub->key_eflags |= 1 << KEY_EFLAG_CA; + return 0; + } + return 0; } diff --git a/include/crypto/public_key.h b/include/crypto/public_key.h index 6d61695e1cdeb..c401762850f20 100644 --- a/include/crypto/public_key.h +++ b/include/crypto/public_key.h @@ -28,6 +28,8 @@ struct public_key { bool key_is_private; const char *id_type; const char *pkey_algo; + unsigned long key_eflags; /* key extension flags */ +#define KEY_EFLAG_CA 0 /* set if the CA basic constraints is set */ }; extern void public_key_free(struct public_key *key);