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charset="UTF-8" X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: DD57CC0015 X-Stat-Signature: uzcuuo9kpsa95833of1g9c384i13x58u X-HE-Tag: 1670959351-777628 X-HE-Meta: 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 I/ZjUHek sQivzBhv/qRzfg9mHZO/6s+s/GMNnP/lVaZy9QHHVPDybgYzYGx+LyxSuahRDaCzZ2O2+p5fRxqm65KbQH/NaQZHV5z2g8KVQ9U6il1/fGBoFhdGtY+4mKiEAUwh9H2cqdy5sTj6lsBWeMGNEqCg4ZNJ9AuP/vI5KlzhoHKf8sVGfZZU= 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: On Tue, Dec 13, 2022 at 10:00 AM Jeff Xu wrote: > On Fri, Dec 9, 2022 at 10:29 AM Paul Moore wrote: > > On Fri, Dec 9, 2022 at 11:05 AM wrote: > > > > > > From: Jeff Xu > > > > > > The new security_memfd_create allows lsm to check flags of > > > memfd_create. > > > > > > The security by default system (such as chromeos) can use this > > > to implement system wide lsm to allow only non-executable memfd > > > being created. > > > > > > Signed-off-by: Jeff Xu > > > Reported-by: kernel test robot > > > --- > > > include/linux/lsm_hook_defs.h | 1 + > > > include/linux/lsm_hooks.h | 4 ++++ > > > include/linux/security.h | 6 ++++++ > > > mm/memfd.c | 5 +++++ > > > security/security.c | 5 +++++ > > > 5 files changed, 21 insertions(+) > > > > We typically require at least one in-tree LSM implementation to > > accompany a new LSM hook. Beyond simply providing proof that the hook > > has value, it helps provide a functional example both for reviewers as > > well as future LSM implementations. Also, while the BPF LSM is > > definitely "in-tree", its nature is such that the actual > > implementation lives out-of-tree; something like SELinux, AppArmor, > > Smack, etc. are much more desirable from an in-tree example > > perspective. > > Thanks for the comments. > Would that be OK if I add a new LSM in the kernel to block executable > memfd creation ? If you would be proposing the LSM only to meet the requirement of providing an in-tree LSM example, no that would definitely *not* be okay. Proposing a new LSM involves documenting a meaningful security model, implementing it, developing tests, going through a (likely multi-step) review process, and finally accepting the long term maintenance responsibilities of this new LSM. If you are proposing a new LSM because you feel the current LSMs do not provide a security model which meets your needs, then yes, proposing a new LSM might be a good idea. However, if you are proposing a new LSM because you don't want to learn how to add a new hook to an existing LSM, then I suspect you are misguided/misinformed with the amount of work involved in submitting a new LSM. > Alternatively, it might be possible to add this into SELinux or > landlock, it will be a larger change. It will be a much smaller change than submitting a new LSM, and it would have infinitely more value to the community than a throw-away LSM where the only use-case is getting your code merged upstream. -- paul-moore.com