From 12f48aa65e45a50bba6df07db56b77ccfbdb3f77 Mon Sep 17 00:00:00 2001
From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Date: Sun, 7 Aug 2022 01:26:41 +0300
Subject: libcamera: pub_key: Support openssl as an alternative to gnutls

Support verify IPA signatures with openssl as an alternative to gnutls,
to offer more flexibility in the selection of dependencies. Use gnutls
by default, for no specific reason as both are equally well supported.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Eric Curtin <ecurtin@redhat.com>
Reviewed-by: Eric Curtin <ecurtin@redhat.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
---
 src/libcamera/pub_key.cpp | 47 +++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 43 insertions(+), 4 deletions(-)

(limited to 'src/libcamera/pub_key.cpp')

diff --git a/src/libcamera/pub_key.cpp b/src/libcamera/pub_key.cpp
index b2045a10..64dfa234 100644
--- a/src/libcamera/pub_key.cpp
+++ b/src/libcamera/pub_key.cpp
@@ -7,7 +7,12 @@
 
 #include "libcamera/internal/pub_key.h"
 
-#if HAVE_GNUTLS
+#if HAVE_CRYPTO
+#include <openssl/evp.h>
+#include <openssl/rsa.h>
+#include <openssl/sha.h>
+#include <openssl/x509.h>
+#elif HAVE_GNUTLS
 #include <gnutls/abstract.h>
 #endif
 
@@ -33,7 +38,14 @@ namespace libcamera {
 PubKey::PubKey([[maybe_unused]] Span<const uint8_t> key)
 	: valid_(false)
 {
-#if HAVE_GNUTLS
+#if HAVE_CRYPTO
+	const uint8_t *data = key.data();
+	pubkey_ = d2i_PUBKEY(nullptr, &data, key.size());
+	if (!pubkey_)
+		return;
+
+	valid_ = true;
+#elif HAVE_GNUTLS
 	int ret = gnutls_pubkey_init(&pubkey_);
 	if (ret < 0)
 		return;
@@ -52,7 +64,9 @@ PubKey::PubKey([[maybe_unused]] Span<const uint8_t> key)
 
 PubKey::~PubKey()
 {
-#if HAVE_GNUTLS
+#if HAVE_CRYPTO
+	EVP_PKEY_free(pubkey_);
+#elif HAVE_GNUTLS
 	gnutls_pubkey_deinit(pubkey_);
 #endif
 }
@@ -79,7 +93,32 @@ bool PubKey::verify([[maybe_unused]] Span<const uint8_t> data,
 	if (!valid_)
 		return false;
 
-#if HAVE_GNUTLS
+#if HAVE_CRYPTO
+	/*
+	 * Create and initialize a public key algorithm context for signature
+	 * verification.
+	 */
+	EVP_PKEY_CTX *ctx = EVP_PKEY_CTX_new(pubkey_, nullptr);
+	if (!ctx)
+		return false;
+
+	if (EVP_PKEY_verify_init(ctx) <= 0 ||
+	    EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING) <= 0 ||
+	    EVP_PKEY_CTX_set_signature_md(ctx, EVP_sha256()) <= 0) {
+		EVP_PKEY_CTX_free(ctx);
+		return false;
+	}
+
+	/* Calculate the SHA256 digest of the data. */
+	uint8_t digest[SHA256_DIGEST_LENGTH];
+	SHA256(data.data(), data.size(), digest);
+
+	/* Decrypt the signature and verify it matches the digest. */
+	int ret = EVP_PKEY_verify(ctx, sig.data(), sig.size(), digest,
+				  SHA256_DIGEST_LENGTH);
+	EVP_PKEY_CTX_free(ctx);
+	return ret == 1;
+#elif HAVE_GNUTLS
 	const gnutls_datum_t gnuTlsData{
 		const_cast<unsigned char *>(data.data()),
 		static_cast<unsigned int>(data.size())
-- 
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