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[2003:d8:2f12:1b00:5d6b:db26:e2b7:12]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-45382366f88sm11928625e9.30.2025.06.25.01.09.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 25 Jun 2025 01:09:30 -0700 (PDT) Message-ID: Date: Wed, 25 Jun 2025 10:09:28 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] fs: export anon_inode_make_secure_inode() and fix secretmem LSM bypass To: Vlastimil Babka , Peter Zijlstra Cc: Christoph Hellwig , Christian Brauner , Sean Christopherson , Mike Rapoport , Shivank Garg , akpm@linux-foundation.org, paul@paul-moore.com, viro@zeniv.linux.org.uk, willy@infradead.org, pbonzini@redhat.com, tabba@google.com, afranji@google.com, ackerleytng@google.com, jack@suse.cz, cgzones@googlemail.com, ira.weiny@intel.com, roypat@amazon.co.uk, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org References: <20250619-fixpunkt-querfeldein-53eb22d0135f@brauner> <20250619-ablichten-korpulent-0efe2ddd0ee6@brauner> <20250623-warmwasser-giftig-ff656fce89ad@brauner> <20250623142836.GT1613200@noisy.programming.kicks-ass.net> From: David Hildenbrand Autocrypt: addr=david@redhat.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: D60C8140005 X-Stat-Signature: zib1pab737zjyjjk9t8qreipfzxgrf1d X-Rspam-User: X-HE-Tag: 1750838975-386849 X-HE-Meta: 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 SqOen0xb 4LN2x0qkCaA/qCLQuNZORftseeRGUvqLCqZn2rlHFYRVQBTTNCuTS+N2RPxWyxWugNJkal/qWBVIL4QO867AM2qurj+GCQYWzTEmlg8+L8rGUqYm7gslS3Jnhsw4afand3RxVYNIorwP4kcXgQ1Oq7ZfNO8eOMEA3HKWjOvE53IQMtSGzPq1G85X+KQMGFIVBzHf2dpGkH6Ff3RjfK4ENIDJSrM1qdrja73u7qpTzyOiwGTPlJrWhMUVw7UQJVp8thElbdzDYcs8PHwrJVC7Ws6NCLm6Eza1eoLUkTyWAJcXjTlIIhjqp4kVFXEuC2kP/lx2OSZrmF2KqeJqp1Lntz273R+KCKQDnS6Q/HS2XzVdOL5crkmRggbwRooGi3KfmNY21Yj88bvJS4AFv+CnkTe9WZsgkE+pyecE8cM/i/0pntd6xdlwuleBuVqiPGpKniUqir88QauOI1hU= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 25.06.25 10:02, Vlastimil Babka wrote: > On 6/23/25 16:28, Peter Zijlstra wrote: >> On Mon, Jun 23, 2025 at 04:21:15PM +0200, Vlastimil Babka wrote: >>> On 6/23/25 16:01, Christoph Hellwig wrote: >>>> On Mon, Jun 23, 2025 at 07:00:39AM -0700, Christoph Hellwig wrote: >>>>> On Mon, Jun 23, 2025 at 12:16:27PM +0200, Christian Brauner wrote: >>>>>> I'm more than happy to switch a bunch of our exports so that we only >>>>>> allow them for specific modules. But for that we also need >>>>>> EXPOR_SYMBOL_FOR_MODULES() so we can switch our non-gpl versions. >>>>> >>>>> Huh? Any export for a specific in-tree module (or set thereof) is >>>>> by definition internals and an _GPL export if perfectly fine and >>>>> expected. >>> >>> Peterz tells me EXPORT_SYMBOL_GPL_FOR_MODULES() is not limited to in-tree >>> modules, so external module with GPL and matching name can import. >>> >>> But if we're targetting in-tree stuff like kvm, we don't need to provide a >>> non-GPL variant I think? >> >> So the purpose was to limit specific symbols to known in-tree module >> users (hence GPL only). >> >> Eg. KVM; x86 exports a fair amount of low level stuff just because KVM. >> Nobody else should be touching those symbols. >> >> If you have a pile of symbols for !GPL / out-of-tree consumers, it >> doesn't really make sense to limit the export to a named set of modules, >> does it? >> >> So yes, nothing limits things to in-tree modules per-se. The >> infrastructure only really cares about module names (and implicitly >> trusts the OS to not overwrite existing kernel modules etc.). So you >> could add an out-of-tree module name to the list (or have an out-of-free >> module have a name that matches a glob; "kvm-vmware" would match "kvm-*" >> for example). >> >> But that is very much beyond the intention of things. > > So AFAIK we have a way to recognize out of tree modules when loading, as > there's a taint just for that. Then the same mechanism could perhaps just > refuse loading them if they use any _FOR_MODULES() export, regardless of > name? Then the _GPL_ part would become implicit and redundant and we could > drop it as Christoph suggested? If that is possible, that sounds indeed nice. -- Cheers, David / dhildenb