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Biederman" , sonicadvance1@gmail.com Cc: Kees Cook , David Hildenbrand , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, kernel-dev@igalia.com, kernel@gpiccoli.net, oleg@redhat.com, yzaikin@google.com, mcgrof@kernel.org, akpm@linux-foundation.org, brauner@kernel.org, viro@zeniv.linux.org.uk, willy@infradead.org, dave@stgolabs.net, joshua@froggi.es References: <20230907204256.3700336-1-gpiccoli@igalia.com> <202310091034.4F58841@keescook> <8dc5069f-5642-cc5b-60e0-0ed3789c780b@igalia.com> <871qctwlpx.fsf@email.froward.int.ebiederm.org> From: "Guilherme G. Piccoli" In-Reply-To: <871qctwlpx.fsf@email.froward.int.ebiederm.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 2877416000E X-Stat-Signature: bzs8pdnk658g3wmze7tkifepmk1prnzz X-HE-Tag: 1699903073-796777 X-HE-Meta: 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 UUdjrc4y JcBfwMeZooPf4PcVuLxMCJJE6Nx66VUwa5yl7CNl9kPlAGfaBU66wGjkzBy48a7GYziBBqYL6Txmhomd0676Mw4Xrhd0TMqN1VVgl7wm7dsaxBglS8ZitgNu/SaOC64RvtsEVIM6dtDGj7ASzbu4py7ODj99B49wIct6tCF9gaEY/FdWwCnM6tmka8LQOHI5T0H9LtcAXi+hLY2ABFOjvC+ENBcINYsGSugpPWFE4GQSjLFgnSjSUJ3XtPNNy5WV7pVJ+p8zzDcMRplA0S/TQRUd5xGVDCBPpYzZJLno6hCp5wJ8v2A7gUd6Zzvx5GYUYlcZvlWKcgSNv885Pr9w2vRYngtNbzftTlDcr X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, 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 13/11/2023 15:29, Eric W. Biederman wrote: > [...] > Currently there is a mechanism in the kernel for changing > /proc/self/exe. Would that be reasonable to use in this case? > > It came from the checkpoint/restart work, but given that it is already > implemented it seems like the path of least resistance to get your > binfmt_misc that wants to look like binfmt_elf to use that mechanism. > > Eric > Thanks Eric! I'm curious on how that would work: we'd change the symlink of the emulator? So, the *emulated* software, when reading that, would see the correct symlink? Also, just to fully clarify: are you suggesting we hook the new binfmt_misc flag proposed here to the internal kernel way of changing the proc/self/exe symlink, or are you suggesting we use the prctl() tune from the emulator, like the userspace changing its own symlink? One of the biggest concerns I have with this kind of approach is that changing the symlink actually...changes it - the binary mapping itself, I mean. Whereas my way was a "fake" change, just expose one thing for the emulated app, but changes nothing else... Cheers, Guilherme