From 30eae2b037af54b24109dcaea21db46f6285c69b Mon Sep 17 00:00:00 2001 From: Eric Snowberg Date: Thu, 2 Mar 2023 11:46:49 -0500 Subject: 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 Reviewed-by: Mimi Zohar Reviewed-by: Jarkko Sakkinen Tested-by: Mimi Zohar Signed-off-by: Jarkko Sakkinen --- crypto/asymmetric_keys/x509_cert_parser.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) (limited to 'crypto') diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c index 7a9b084e2043..77547d4bd94d 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; } -- cgit v1.2.3