extract-cert: fix build with OpenSSL 4

OpenSSL 4.0 removed the ENGINE API. <openssl/engine.h> still exists as a
source-compatibility stub, so both binaries fail to link:

  ld.lld: error: undefined symbol: ENGINE_load_builtin_engines
  ld.lld: error: undefined symbol: ENGINE_by_id
  ld.lld: error: undefined symbol: ENGINE_init
  ld.lld: error: undefined symbol: ENGINE_ctrl_cmd_string
  ld.lld: error: undefined symbol: ENGINE_load_public_key

The ENGINE use is confined to the "pkcs11:" input branch of each tool, so
compile that branch out on OpenSSL 4 and diagnose the unsupported input
instead. Reading certificates and public keys from PEM files, which is
what the kernel build and most other users do, is unaffected.

Providers supersede engines, but none exposes an equivalent of the pkcs11
engine's LOAD_CERT_CTRL command, so there is nothing to port to yet.

AI-Generated: Uses Claude Code
Signed-off-by: Khem Raj <raj.khem@gmail.com>

meta-oe/recipes-devtools/extract-cert/extract-cert/0001-Do-not-use-the-ENGINE-API-with-OpenSSL-4.patch

@@ -0,0 +1,99 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Khem Raj <raj.khem@gmail.com>
+Date: Wed, 3 Sep 2026 01:30:00 +0000
+Subject: [PATCH] Do not use the ENGINE API with OpenSSL 4
+
+OpenSSL 4.0 removed the ENGINE API.  <openssl/engine.h> still exists, but
+only as a source-compatibility stub, so both binaries now fail to link:
+
+  ld.lld: error: undefined symbol: ENGINE_load_builtin_engines
+  ld.lld: error: undefined symbol: ENGINE_by_id
+  ld.lld: error: undefined symbol: ENGINE_init
+  ld.lld: error: undefined symbol: ENGINE_ctrl_cmd_string
+  ld.lld: error: undefined symbol: ENGINE_load_public_key
+
+The ENGINE use is confined to the "pkcs11:" input branch of each tool, so
+compile that branch out on OpenSSL 4 and diagnose the unsupported input
+instead.  Reading certificates and public keys from PEM files - which is
+what the kernel build and most other users actually do - is unaffected.
+
+Providers supersede engines, but no provider exposes an equivalent of the
+pkcs11 engine's LOAD_CERT_CTRL command, so there is nothing to port to
+yet; pkcs11-provider based support would be a separate feature.
+
+Upstream-Status: Pending
+
+Signed-off-by: Khem Raj <raj.khem@gmail.com>
+---
+--- a/extract-cert.c
++++ b/extract-cert.c
+@@ -21,7 +21,9 @@
+ #include <openssl/bio.h>
+ #include <openssl/pem.h>
+ #include <openssl/err.h>
++#if OPENSSL_VERSION_MAJOR < 4
+ #include <openssl/engine.h>
++#endif
+ 
+ #define PKEY_ID_PKCS7 2
+ 
+@@ -112,6 +114,16 @@
+ 		fclose(f);
+ 		exit(0);
+ 	} else if (!strncmp(cert_src, "pkcs11:", 7)) {
++#if OPENSSL_VERSION_MAJOR >= 4
++		/*
++		 * OpenSSL 4.0 removed the ENGINE API, and with it the pkcs11
++		 * engine that was used here to pull an object off a token.  No
++		 * provider based replacement for the engine's LOAD_CERT_CTRL
++		 * command exists, so fail loudly rather than quietly emitting
++		 * nothing.
++		 */
++		ERR(1, "PKCS#11 URIs require OpenSSL < 4.0 (ENGINE API removed)");
++#else
+ 		ENGINE *e;
+ 		struct {
+ 			const char *cert_id;
+@@ -134,6 +146,7 @@
+ 		ENGINE_ctrl_cmd(e, "LOAD_CERT_CTRL", 0, &parms, NULL, 1);
+ 		ERR(!parms.cert, "Get X.509 from PKCS#11");
+ 		write_cert(parms.cert);
++#endif
+ 	} else {
+ 		BIO *b;
+ 		X509 *x509;
+--- a/spki-hash.c
++++ b/spki-hash.c
+@@ -23,7 +23,9 @@
+ #include <openssl/bio.h>
+ #include <openssl/pem.h>
+ #include <openssl/err.h>
++#if OPENSSL_VERSION_MAJOR < 4
+ #include <openssl/engine.h>
++#endif
+ 
+ #define PKEY_ID_PKCS7 2
+ 
+@@ -110,6 +112,14 @@
+ 	src = argv[1];
+ 
+ 	if (!strncmp(src, "pkcs11:", 7)) {
++#if OPENSSL_VERSION_MAJOR >= 4
++		/*
++		 * OpenSSL 4.0 removed the ENGINE API, and with it the pkcs11
++		 * engine that was used here to load a public key off a token.
++		 * Fail loudly rather than quietly hashing nothing.
++		 */
++		ERR(1, "PKCS#11 URIs require OpenSSL < 4.0 (ENGINE API removed)");
++#else
+ 		ENGINE *e;
+ 		ENGINE_load_builtin_engines();
+ 		drain_openssl_errors();
+@@ -124,6 +134,7 @@
+ 
+ 		key = ENGINE_load_public_key(e, src, NULL, NULL);
+ 		ERR(!key, "ENGINE_load_public_key");
++#endif
+ 	} else {
+ 		BIO *b;
+ 

meta-oe/recipes-devtools/extract-cert/extract-cert_0.3.bb

@@ -4,7 +4,9 @@ LIC_FILES_CHKSUM = "file://COPYING;md5=4fbd65380cdd255951079008b364516c"
 
 DEPENDS = "openssl"
 
-SRC_URI = "git://git.pengutronix.de/git/extract-cert;protocol=https;branch=master;"
+SRC_URI = "git://git.pengutronix.de/git/extract-cert;protocol=https;branch=master; \
+           file://0001-Do-not-use-the-ENGINE-API-with-OpenSSL-4.patch \
+           "
 SRCREV = "d652b4e8279aef2a85f58676ab472744bafeafc9"