[PATCH v2 1/1] sign-file: Do not attempt to use the ENGINE_* API if it's not available

[Lee Jones]

OpenSSL's ENGINE API is deprecated in OpenSSL v3.0.

Use OPENSSL_NO_ENGINE to ensure the ENGINE API is only used if it is
present.  This will safeguard against compile errors when using SSL
implementations which lack support for this deprecated API.

Cc: David Howells <dhowells@xxxxxxxxxx>
Cc: David Woodhouse <dwmw2@xxxxxxxxxxxxx>
Cc: Eric Biggers <ebiggers@xxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: keyrings@xxxxxxxxxxxxxxx
Co-developed-by: Adam Langley <agl@xxxxxxxxxx>
Signed-off-by: Lee Jones <lee.jones@xxxxxxxxxx>
---
v2: Clear up subject and patch description to avoid confusion

scripts/sign-file.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/scripts/sign-file.c b/scripts/sign-file.c
index fbd34b8e8f578..fa3fa59db6669 100644
--- a/scripts/sign-file.c
+++ b/scripts/sign-file.c
@@ -135,7 +135,9 @@ static int pem_pw_cb(char *buf, int len, int w, void *v)
 static EVP_PKEY *read_private_key(const char *private_key_name)
 {
 	EVP_PKEY *private_key;
+	BIO *b;
 
+#ifndef OPENSSL_NO_ENGINE
 	if (!strncmp(private_key_name, "pkcs11:", 7)) {
 		ENGINE *e;
 
@@ -153,17 +155,16 @@ static EVP_PKEY *read_private_key(const char *private_key_name)
 		private_key = ENGINE_load_private_key(e, private_key_name,
 						      NULL, NULL);
 		ERR(!private_key, "%s", private_key_name);
-	} else {
-		BIO *b;
-
-		b = BIO_new_file(private_key_name, "rb");
-		ERR(!b, "%s", private_key_name);
-		private_key = PEM_read_bio_PrivateKey(b, NULL, pem_pw_cb,
-						      NULL);
-		ERR(!private_key, "%s", private_key_name);
-		BIO_free(b);
+		return private_key;
 	}
+#endif
 
+	b = BIO_new_file(private_key_name, "rb");
+	ERR(!b, "%s", private_key_name);
+	private_key = PEM_read_bio_PrivateKey(b, NULL, pem_pw_cb,
+					      NULL);
+	ERR(!private_key, "%s", private_key_name);
+	BIO_free(b);
 	return private_key;
 }