Toggle quote (129 lines)
> On 2024-09-04 18:42, Ludovic Courtès wrote:
>
>> Hi Jacopo,
>>
>> Jacopo Mondi <jacopo.mondi@ideasonboard.com> skribis:
>>
>>> Not exactly. In libcamera, apart from creating a library to ease all
>>> the camera stack plumbing, we're creating an ecosystem of open-source
>>> 3A algorithms (what we call the IPA modules).
>>>
>>> Camera vendors and ODMs which invested in products with specific
>>> camera features, consider 3A algorithms and their tuning their secret
>>> sauce and are usually not willing to consider releasing them as open
>>> source with, fortunately, notable exceptions such as RaspberryPi
>>>
>>> Please note that all the platforms libcamera supports have an
>>> open-source 3A algorithm module available part of the main code base,
>>> and we consider open source 3A modules our 'first class citizens' and
>>> we're willing to develop and maintain them in libcamera mainline
>>> branch as free software, but at this point we have to provide a way for
>>> third-parties to load binary modules if they want to.
>>>
>>> The alternative is to have them continue developing camera stacks
>>> fully behind closed doors as it has been done so far.
>>
>> OK, I see, thanks for explaining the context.
>>
>>> As said, modules not built against the libcamera sources will not be
>>> signed, as they are distributed by other means by a vendor in binary
>>> form. To establish if a module has been built with the libcamera
>>> sources or not, we sign it during the build with a volatile key and
>>> validate the signature at run-time, when the IPA module is loaded.
>>>
>>> IPA modules for which the signature is not valid (either because they
>>> are distributed as binaries or, as in this case, because the build
>>> system strips symbols before installing the objects) are loaded in an
>>> isolated process and instead of being operated with direct function
>>> calls, we have implemented an IPC mechanism to communicate with them.
>>> This path is way less tested by our regular users and in our daily
>>> work on libcamera. Vendors that are running their binaries as isolated
>>> might have fixed issues here and there but maybe they have not
>>> reported the issue and the associated fix upstream (we have no control
>>> over this).
>>>
>>> For this reason I don't suggest running modules as isolated, even more
>>> if you have no reasons to do so. If all it takes is re-signing IPA modules
>>> after stripping them as Andrew did I would really consider doing that.
>>
>> Yeah, got it. The other option, with the understanding that IPA modules
>> are all going to be free software here, would be to dismiss both the
>> authentication and the isolation mechanism, possibly with a custom
>> patch. It seems like the change wouldn’t be too intrusive and it would
>> solve the problem for “grafts” as well (grafts modify files in a
>> non-functional way).
>
> On 2024-09-02 10:45, Andrew Tropin via Bug reports for GNU Guix wrote:
>> Anyway, I think the current most reasonable solution is to remove
>> signing step at all, because the signaturs will be invalidated by
>> grafting anyway and make it work somehow (either by loading in
>> isolation if it's possible or by loading unsigned libraries without
>> signature check directly).
>
> Everything indicates that we need to disable module authentication.
>
> Jacopo, I think I'll patch IPAManager::isSignatureValid to always return
> true.
>
> https://git.libcamera.org/libcamera/libcamera.git/tree/src/libcamera/ipa_manager.cpp#n285
>
> Like that:
>
> From c99706475cde3d963a17f4f8871149711ce6c467 Mon Sep 17 00:00:00 2001
> From: Andrew Tropin <andrew@trop.in>
> Date: Wed, 4 Sep 2024 21:36:16 +0400
> Subject: [PATCH] libcamera: ipa_manager: Disable signature verification
>
> ---
> src/libcamera/ipa_manager.cpp | 28 +++++-----------------------
> 1 file changed, 5 insertions(+), 23 deletions(-)
>
> diff --git a/src/libcamera/ipa_manager.cpp b/src/libcamera/ipa_manager.cpp
> index cfc24d38..4fd3cf3e 100644
> --- a/src/libcamera/ipa_manager.cpp
> +++ b/src/libcamera/ipa_manager.cpp
> @@ -284,33 +284,15 @@ IPAModule *IPAManager::module(PipelineHandler *pipe, uint32_t minVersion,
>
> bool IPAManager::isSignatureValid([[maybe_unused]] IPAModule *ipa) const
> {
> -#if HAVE_IPA_PUBKEY
> - char *force = utils::secure_getenv("LIBCAMERA_IPA_FORCE_ISOLATION");
> - if (force && force[0] != '\0') {
> - LOG(IPAManager, Debug)
> - << "Isolation of IPA module " << ipa->path()
> - << " forced through environment variable";
> - return false;
> - }
> -
> - File file{ ipa->path() };
> - if (!file.open(File::OpenModeFlag::ReadOnly))
> - return false;
> -
> - Span<uint8_t> data = file.map();
> - if (data.empty())
> - return false;
> -
> - bool valid = pubKey_.verify(data, ipa->signature());
> + LOG(IPAManager, Debug)
> + << "Signature verification is disabled by Guix. "
> + << "See https://issues.guix.gnu.org/72828 for more details.";
>
> LOG(IPAManager, Debug)
> << "IPA module " << ipa->path() << " signature is "
> - << (valid ? "valid" : "not valid");
> + << "not verified (verification skipped).";
>
> - return valid;
> -#else
> - return false;
> -#endif
> + return true;
> }
>
> } /* namespace libcamera */
> --
> 2.45.2
>
>
> Everyone is ok with it?
