Messages in this thread | | | From | Dawid Ciezarkiewicz <> | Date | Fri, 15 Sep 2017 10:57:30 -0700 | Subject | Read-only `slaves` with shared subtrees? |
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Hi,
(Please keep me in CC me when responding.)
I have an use-case for shared subtrees that is not covered by:
https://www.kernel.org/doc/Documentation/filesystems/sharedsubtree.txt
and I wasn't able to figure out any working solution - it might not be possible ATM.
Long story short: I'd like the `slave` mount (service in a container) to mount propagated events as RO, no matter how did `master` (host) mount them. Host might need that data RW, but slave must have it RO only.
I'm using Linux containers to isolate processes. I need the container to follow part of the host system mount tree, but not have a write-access to it (for security reasons). It's a trivial setup as long as everything is static, but as soon as a part of what the container needs to access is mounted/unmounted at runtime (and thus shared subtrees are involved), there seems to be no way to control the flags of the propagated mount events.
I might be able to write a patch implementing this, but before attempting that, I'd like to confirm:
* Is it even a good idea? * Is it maybe already possible by some other means? * Is it an use-case that might potentially be worth supporting in the mainline? If so: any hints/ideas about the design and API?
Best Regards, -- Dawid Ciezarkiewicz Software Engineer at Rubrik
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