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

From: Kees Cook <keescook@chromium.org>
To: Lee Jones <lee.jones@linaro.org>
Cc: David Howells <dhowells@redhat.com>,
	David Woodhouse <dwmw2@infradead.org>,
	keyrings@vger.kernel.org, Adam Langley <agl@google.com>,
	linux-kernel@vger.kernel.org, Eric Biggers <ebiggers@kernel.org>
Subject: Re: [PATCH v2 1/1] sign-file: Do not attempt to use the ENGINE_* API if it's not available
Date: Thu, 10 Mar 2022 08:51:56 -0800	[thread overview]
Message-ID: <202203100851.C00D9AB73@keescook> (raw)
In-Reply-To: <Yicwb+Ceiu8JjVIS@google.com>

On Tue, Mar 08, 2022 at 10:31:11AM +0000, Lee Jones wrote:
> 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.

On Fedora rawhide, I'm still seeing a bunch of warnings:

scripts/sign-file.c: In function 'display_openssl_errors':
scripts/sign-file.c:89:9: warning: 'ERR_get_error_line' is deprecated: Since OpenSSL 3.0 [-Wdeprecat
ed-declarations]
   89 |         while ((e = ERR_get_error_line(&file, &line))) {
      |         ^~~~~
In file included from scripts/sign-file.c:29:
/usr/include/openssl/err.h:411:15: note: declared here
  411 | unsigned long ERR_get_error_line(const char **file, int *line);
      |               ^~~~~~~~~~~~~~~~~~
scripts/sign-file.c: In function 'drain_openssl_errors':
scripts/sign-file.c:102:9: warning: 'ERR_get_error_line' is deprecated: Since OpenSSL 3.0 [-Wdepreca
ted-declarations]
  102 |         while (ERR_get_error_line(&file, &line)) {}
      |         ^~~~~
/usr/include/openssl/err.h:411:15: note: declared here
  411 | unsigned long ERR_get_error_line(const char **file, int *line);
      |               ^~~~~~~~~~~~~~~~~~
...

>
> Cc: David Howells <dhowells@redhat.com>
> Cc: David Woodhouse <dwmw2@infradead.org>
> Cc: Eric Biggers <ebiggers@kernel.org>
> Cc: Kees Cook <keescook@chromium.org>
> Cc: keyrings@vger.kernel.org
> Co-developed-by: Adam Langley <agl@google.com>
> Signed-off-by: Lee Jones <lee.jones@linaro.org>
> ---
> 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;
>  }

--
Kees Cook