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Sat, 3 May 2025 04:20:06 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ThreadId: T5f9a5891fefab612 Date: Sat, 03 May 2025 10:19:17 +0200 From: "Arnout Engelen" To: "James Bottomley" , =?UTF-8?Q?Thomas_Wei=C3=9Fschuh?= Cc: "Masahiro Yamada" , "Nathan Chancellor" , "Arnd Bergmann" , "Luis Chamberlain" , "Petr Pavlu" , "Sami Tolvanen" , "Daniel Gomez" , "Paul Moore" , "James Morris" , "Serge E. Hallyn" , "Jonathan Corbet" , "Madhavan Srinivasan" , "Michael Ellerman" , "Nicholas Piggin" , "Christophe Leroy" , "Naveen N Rao" , "Mimi Zohar" , "Roberto Sassu" , "Dmitry Kasatkin" , "Eric Snowberg" , "Nicolas Schier" , =?UTF-8?Q?Fabian_Gr=C3=BCnbichler?= , "Mattia Rizzolo" , kpcyrd , "Christian Heusel" , =?UTF-8?Q?C=C3=A2ju_Mihai-Drosi?= , linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-modules@vger.kernel.org, linux-security-module@vger.kernel.org, linux-doc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-integrity@vger.kernel.org Message-Id: <072b392f-8122-4e4f-9a94-700dadcc0529@app.fastmail.com> In-Reply-To: References: <20250429-module-hashes-v3-0-00e9258def9e@weissschuh.net> <840b0334-71e4-45b1-80b0-e883586ba05c@t-8ch.de> Subject: Re: [PATCH v3 0/9] module: Introduce hash-based integrity checking Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On Fri, May 2, 2025, at 15:30, James Bottomley wrote: > On Fri, 2025-05-02 at 08:53 +0200, Thomas Wei=C3=9Fschuh wrote: > > Specifically the output of any party can recreate bit-by-bit > > identical copies of all specified artifacta previous build (the > > public key, module signatures) is not available during the rebuild or > > verification. >=20 > You just strip the signatures before verifying reproducibility. If the goal is: "verify the Linux Kernel is reproducible", that could wo= rk. It gets increasingly cumbersome when you're trying to check the reproduc= ibility of some larger artifact that embeds the Linux kernel (and lots of other = stuff), like an ISO or disk image, though: you'd have to unpack/mount it, check = all its contents individually (perhaps recursively), and strip signatures in 'ju= st the right places'. Writing such tooling is a chore, but of course feasible: diffoscope alre= ady comes a long way (though checking large images may take some resources).= The problem is trusting such tooling: instead of 'simply' checking the image= s are identical, suddenly I now have to convince myself there's no shenanigans possible in the disk image interpretation and other check tooling, which= gets nontrivial fast. > All current secure > build processes (hermetic builds, SLSA and the like) are requiring > output provenance (i.e. signed artifacts). If you try to stand like > Canute against this tide saying "no signed builds", you're simply > opposing progress for the sake of it I don't think anyone is saying 'no signed builds', but we'd enjoy being = able to keep the signatures as detached metadata instead of having to embed them= into the 'actual' artifacts. Kind regards, Arnout