[PATCH] sign-file: add generic engine key support

[James Bottomley <James.Bottomley@HansenPartnership.com>]

The current engine code only supports a non-standard pkcs11 engine
module.  Add code to support any standard engine key module, but leave
the non-standard code alone because it would likely fail to function
with the correct UI_method of collecting the password.

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
---
 scripts/sign-file.c | 39 +++++++++++++++++++++++++++++++++++++--
 1 file changed, 37 insertions(+), 2 deletions(-)

diff --git a/scripts/sign-file.c b/scripts/sign-file.c
index 49f1cf456254..de8d9bb5e657 100644
--- a/scripts/sign-file.c
+++ b/scripts/sign-file.c
@@ -28,6 +28,7 @@
 #include <openssl/pem.h>
 #include <openssl/err.h>
 #include <openssl/engine.h>
+#include <openssl/conf.h>
 
 /*
  * Use CMS if we have openssl-1.0.0 or newer available - otherwise we have to
@@ -122,15 +123,29 @@ static int pem_pw_cb(char *buf, int len, int w, void *v)
 	return pwlen;
 }
 
+static int ui_read(UI *ui, UI_STRING *uis)
+{
+    if (UI_get_string_type(uis) = UIT_PROMPT) {
+        char password[64];
+
+        pem_pw_cb(password, sizeof(password), 0, NULL);
+        UI_set_result(ui, uis, password);
+
+        return 1;
+    }
+    return 0;
+}
+
 static EVP_PKEY *read_private_key(const char *private_key_name)
 {
 	EVP_PKEY *private_key;
 
+	ENGINE_load_builtin_engines();
+	OPENSSL_config(NULL);
+	ERR_clear_error();
 	if (!strncmp(private_key_name, "pkcs11:", 7)) {
 		ENGINE *e;
 
-		ENGINE_load_builtin_engines();
-		ERR_clear_error();
 		e = ENGINE_by_id("pkcs11");
 		ERR(!e, "Load PKCS#11 ENGINE");
 		if (ENGINE_init(e))
@@ -145,11 +160,31 @@ static EVP_PKEY *read_private_key(const char *private_key_name)
 		ERR(!private_key, "%s", private_key_name);
 	} else {
 		BIO *b;
+		ENGINE *e;
 
 		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);
+		for (e = ENGINE_get_first(); !private_key && e != NULL;
+		     e = ENGINE_get_next(e)) {
+			UI_METHOD *ui;
+
+			if (!ENGINE_get_load_privkey_function(e))
+				continue;
+
+			ui = UI_create_method("sign-file");
+			if (!ui)
+				continue;
+
+			UI_method_set_reader(ui, ui_read);
+			private_key = ENGINE_load_private_key(e, private_key_name,
+							      ui, NULL);
+			UI_destroy_method(ui);
+			if (private_key)
+				ERR_clear_error(); /* initial key read failed */
+		}
+
 		ERR(!private_key, "%s", private_key_name);
 		BIO_free(b);
 	}
-- 
2.12.3