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smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ZjmHLl4s; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ZjmHLl4s" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E570AC4CEDD; Tue, 25 Feb 2025 15:06:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1740495977; bh=ulSlGShANn0qabJ6PwZZ9yBHZeUtO9LZVEnKl8528tc=; h=Date:From:To:CC:Subject:In-Reply-To:References:From; b=ZjmHLl4sZAOy1F8GiI8E8GAiKPa5p7MSwqaQtXxYzGw1lXbbMPoC1vIM1vTXHDE1C c4lWCmbEi/mIYjG1s4rOtAhvqeyyd4jEDGnnNnVa5dB/fp/Khy1h5TlavXOdDIHJiw oHx4XaWEPVB0jlViX7Qc3tpS87j0ppDz3TW7gEKsJB0zTzwIGkCbXftF7ysnFKwGs/ hurOr1uaJZ1iNMf8vzSXGfLRCZHAZrYRIrmX4uhh7pr4zKPTfmOrOoSaDw7jhMBx6G tYSI1/1WAzzP4TEugmX0mOEYpTLVWOfCvWoOzvnpEDsMDKp/nZyTIv5/is/Sn9nMgy jrwQZeOmBeQmw== Date: Tue, 25 Feb 2025 07:06:13 -0800 From: Kees Cook To: Lorenzo Stoakes , "Berg, Benjamin" CC: "jeffxu@chromium.org" , "Jason@zx2c4.com" , "adobriyan@gmail.com" , "deller@gmx.de" , "gerg@kernel.org" , "anna-maria@linutronix.de" , "davem@davemloft.net" , "avagin@gmail.com" , "mhocko@suse.com" , "enh@google.com" , "thomas.weissschuh@linutronix.de" , "hch@lst.de" , "hca@linux.ibm.com" , "peterz@infradead.org" , "adhemerval.zanella@linaro.org" , "linux-kernel@vger.kernel.org" , "ojeda@kernel.org" , "jannh@google.com" , "f.fainelli@gmail.com" , "sroettger@google.com" , "ardb@google.com" , "jorgelo@chromium.org" , "rdunlap@infradead.org" , "mark.rutland@arm.com" , "Liam.Howlett@oracle.com" , "vbabka@suse.cz" , "mpe@ellerman.id.au" , "oleg@redhat.com" , "willy@infradead.org" , "keescook@chromium.org" , "peterx@redhat.com" , "mike.rapoport@gmail.com" , "mingo@kernel.org" , "rientjes@google.com" , "groeck@chromium.org" , "linus.walleij@linaro.org" , "pedro.falcato@gmail.com" , "ardb@kernel.org" , "42.hyeyoo@gmail.com" <42.hyeyoo@gmail.com>, "linux-mm@kvack.org" , "johannes@sipsolutions.net" , "linux-hardening@vger.kernel.org" , "torvalds@linux-foundation.org" , "akpm@linux-foundation.org" , "dave.hansen@linux.intel.com" , "aleksandr.mikhalitsyn@canonical.com" Subject: Re: [PATCH v7 5/7] mseal, system mappings: enable uml architecture User-Agent: K-9 Mail for Android In-Reply-To: References: <20250224225246.3712295-1-jeffxu@google.com> <20250224225246.3712295-6-jeffxu@google.com> <96ebddf3fe31353c89f6a4680eaeb2793c25cd09.camel@intel.com> Message-ID: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On February 25, 2025 2:37:11 AM PST, Lorenzo Stoakes wrote: >On Tue, Feb 25, 2025 at 08:45:21AM +0000, Berg, Benjamin wrote: >> Hi, >> >> On Tue, 2025-02-25 at 06:22 +0000, Lorenzo Stoakes wrote: >> > On Mon, Feb 24, 2025 at 10:52:44PM +0000, jeffxu@chromium=2Eorg=C2=A0= wrote: >> > > From: Jeff Xu >> > > >> > > Provide support for CONFIG_MSEAL_SYSTEM_MAPPINGS on UML, covering >> > > the vdso=2E >> > > >> > > Testing passes on UML=2E >> > >> > Maybe expand on this by stating that it has been confirmed by Benjami= n (I >> > _believe_) that UML has no need for problematic relocation so this is= known to >> > be good=2E >> >> I may well be misreading this message, but this sounds to me that this >> is a misinterpretation=2E So, just to clarify in case that is needed=2E >> >> CONFIG_MSEAL_SYSTEM_MAPPINGS does work fine for the UML kernel=2E >> However, the UML kernel is a normal userspace application itself and >> for this application to run, the host kernel must have the feature >> disabled=2E >> >> So, UML supports the feature=2E But it still *cannot* run on a host >> machine that has the feature enabled=2E > >Sigh ok=2E Apologies if I misunderstood=2E > >Is there any point having this for the 'guest' system? I mean security wi= se are >we concerned about sealing of system mappings? UML guests are used for testing=2E For example, it's the default target fo= r KUnit's scripts=2E Having sealing working in the guest seems generally us= eful to me=2E > >I feel like having this here might just add confusion and churn if it's n= ot >useful=2E > >If this is useless for UML guest, let's just drop this patch=2E But on the flip side, it's certainly not critical to have UML supported=2E= I guess I just don't see a down side to keeping the patch=2E -Kees --=20 Kees Cook