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Message-Id: <704291cbc90ca3aaaaa56b191017c1400963cf12.1695921657.git.lukas@wunner.de>
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From:   Lukas Wunner <lukas@wunner.de>
Date:   Thu, 28 Sep 2023 19:32:32 +0200
Subject: [PATCH 02/12] X.509: Parse Subject Alternative Name in certificates
To:     Bjorn Helgaas <helgaas@kernel.org>,
        David Howells <dhowells@redhat.com>,
        David Woodhouse <dwmw2@infradead.org>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        "David S. Miller" <davem@davemloft.net>,
        Alex Williamson <alex.williamson@redhat.com>,
        <linux-pci@vger.kernel.org>, <linux-cxl@vger.kernel.org>,
        <linux-coco@lists.linux.dev>, <keyrings@vger.kernel.org>,
        <linux-crypto@vger.kernel.org>, <kvm@vger.kernel.org>
Cc:     Jonathan Cameron <Jonathan.Cameron@huawei.com>,
        <linuxarm@huawei.com>, David Box <david.e.box@intel.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Dave Jiang <dave.jiang@intel.com>,
        "Li, Ming" <ming4.li@intel.com>, Zhi Wang <zhi.a.wang@intel.com>,
        Alistair Francis <alistair.francis@wdc.com>,
        Wilfred Mallawa <wilfred.mallawa@wdc.com>,
        Alexey Kardashevskiy <aik@amd.com>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        Sean Christopherson <seanjc@google.com>,
        Alexander Graf <graf@amazon.com>
Precedence: bulk

The upcoming support for PCI device authentication with CMA-SPDM
(PCIe r6.1 sec 6.31) requires validating the Subject Alternative Name
in X.509 certificates.

Store a pointer to the Subject Alternative Name upon parsing for
consumption by CMA-SPDM.

Signed-off-by: Lukas Wunner <lukas@wunner.de>
---
 crypto/asymmetric_keys/x509_cert_parser.c | 15 +++++++++++++++
 include/keys/x509-parser.h                |  2 ++
 2 files changed, 17 insertions(+)

diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c
index 0a7049b470c1..18dfd564740b 100644
--- a/crypto/asymmetric_keys/x509_cert_parser.c
+++ b/crypto/asymmetric_keys/x509_cert_parser.c
@@ -579,6 +579,21 @@ int x509_process_extension(void *context, size_t hdrlen,
 		return 0;
 	}
 
+	if (ctx->last_oid == OID_subjectAltName) {
+		/*
+		 * A certificate MUST NOT include more than one instance
+		 * of a particular extension (RFC 5280 sec 4.2).
+		 */
+		if (ctx->cert->raw_san) {
+			pr_err("Duplicate Subject Alternative Name\n");
+			return -EINVAL;
+		}
+
+		ctx->cert->raw_san = v;
+		ctx->cert->raw_san_size = vlen;
+		return 0;
+	}
+
 	if (ctx->last_oid == OID_keyUsage) {
 		/*
 		 * Get hold of the keyUsage bit string
diff --git a/include/keys/x509-parser.h b/include/keys/x509-parser.h
index 7c2ebc84791f..9c6e7cdf4870 100644
--- a/include/keys/x509-parser.h
+++ b/include/keys/x509-parser.h
@@ -32,6 +32,8 @@ struct x509_certificate {
 	unsigned	raw_subject_size;
 	unsigned	raw_skid_size;
 	const void	*raw_skid;		/* Raw subjectKeyId in ASN.1 */
+	const void	*raw_san;		/* Raw subjectAltName in ASN.1 */
+	unsigned	raw_san_size;
 	unsigned	index;
 	bool		seen;			/* Infinite recursion prevention */
 	bool		verified;
-- 
2.40.1