Messages in this thread | | | Subject | Re: [PATCH v7 0/7] Add support for O_MAYEXEC | From | Deven Bowers <> | Date | Tue, 11 Aug 2020 10:18:08 -0700 |
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On 8/11/2020 1:48 AM, Mickaël Salaün wrote:
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>>> It is a >>> good practice to check as soon as possible such properties, and it may >>> enables to avoid (user space) time-of-check to time-of-use (TOCTOU) >>> attacks (i.e. misuse of already open resources). >> >> The assumption that security checks should happen as early as possible >> can actually cause security problems. For example, because seccomp was >> designed to do its checks as early as possible, including before >> ptrace, we had an issue for a long time where the ptrace API could be >> abused to bypass seccomp filters. >> >> Please don't decide that a check must be ordered first _just_ because >> it is a security check. While that can be good for limiting attack >> surface, it can also create issues when the idea is applied too >> broadly. > > I'd be interested with such security issue examples. > > I hope that delaying checks will not be an issue for mechanisms such as > IMA or IPE: > https://lore.kernel.org/lkml/1544699060.6703.11.camel@linux.ibm.com/ > > Any though Mimi, Deven, Chrome OS folks? >
I don't see an issue with IPE. As long as the hypothetical new syscall and associated security hook have the file struct available in the hook, it should integrate fairly easily.
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