From: Chris PeBenito <chpebeni@linux.microsoft.com>
To: SElinux mailing list <selinux@vger.kernel.org>,
brauner@kernel.org, bluca@debian.org
Subject: Proposed feature: fine-grained file descriptors in SELinux
Date: Thu, 9 Nov 2023 13:26:24 -0500 [thread overview]
Message-ID: <da1d9efd-fdc1-4651-8a7a-30ae4a399926@linux.microsoft.com> (raw)
systemd is increasing usage of memfds, pidfds, etc. This is resulting
in a need for wide inheritance of fds across the system. For example in
a lot of systemd interfaces that have a pid field now have a comparable
pidfd interface. dbus-broker and polkit are similarly updated.
Some references from an All Systems Go! talk:
https://cfp.all-systems-go.io/media/all-systems-go-2023/submissions/T3LJAM/resources/ASG_2023_PID_FD-ize_all_the_things_E98Zw9Q.pdf
This is from a few months ago; the switch to PIDFDs is nearly
complete, and we're already seeing denials for this usage.
Since file descriptors are increasing use as references for various
operations, I think it would be useful to have a finer-grained fd class,
so we can limit file descriptor inheritance, particularly as it looks
like systemd/pid1 will need to inherit pidfd file descriptors from
possibly all domains. Specifically, I propose adding new permissions to
the fd class, such as use_pidfd and use_memfd. Then systemd can use
pidfds from any domain, but only use regular fds from trusted domains.
Thoughts?
--
Chris PeBenito
next reply other threads:[~2023-11-09 18:26 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-09 18:26 Chris PeBenito [this message]
2023-11-13 4:52 ` Proposed feature: fine-grained file descriptors in SELinux Paul Moore
2023-11-13 15:35 ` Stephen Smalley
2023-11-14 6:22 ` Paul Moore
2023-11-14 14:14 ` Chris PeBenito
2023-11-14 14:31 ` Stephen Smalley
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