From: Phillip Wood <phillip.wood123@gmail.com>
Date: Thu, 06 Oct 2022 13:05:09 GMT
Subject: Re: [PATCH v2] ssh signing: return an error when signature cannot be read
Message-ID: <ce32d5c7-c62c-b27f-23fa-566cba65c383@dunelm.org.uk>
In-Reply-To: <20221006082817.4uxywfxjokfyml6y@fs>

Hi Fabian

On 06/10/2022 09:28, Fabian Stelzer wrote:
> On 04.10.2022 10:01, Phillip Wood via GitGitGadget wrote:
>> From: Phillip Wood <phillip.wood@dunelm.org.uk>
>>    This patch is based on maint. In the longer term the code could be
>>    simplified by using pipes rather than tempfiles as we do for gpg.
>>    ssh-keygen has supported reading the data to be signed from stdin and
>>    writing the signature to stdout since it introduced signing.
> 
> The ssh-keygen call is already using stdin for the content to sign or 
> verify. The signature and the signing key need to be files passed as 
> parameters to ssh-keygen. I'm not aware of any other option of providing 
> them to it.

We use stdin for the content when verifying but not when signing

	strvec_pushl(&signer.args, use_format->program,
		     "-Y", "sign",
		     "-n", "git",
		     "-f", ssh_signing_key_file,
		     buffer_file->filename.buf,
		     NULL);

	sigchain_push(SIGPIPE, SIG_IGN);
	ret = pipe_command(&signer, NULL, 0, NULL, 0, &signer_stderr, 0);
	sigchain_pop(SIGPIPE);

Note that when verifying with -Y check-novalidate there is a missing 
call to sigchain_push(SIGPIPE, SIG_IGN) as we are passing data over 
stdin so need to ignore SIGPIPE.

Best Wishes

Phillip


> Cheers,
> Fabian
>