Re: POSIX shared memory and dying jails
- In reply to: James Gritton : "Re: POSIX shared memory and dying jails"
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Date: Mon, 02 Aug 2021 10:11:33 UTC
On Fri, 25 Jun 2021 20:18:39 -0700 James Gritton <email@example.com> wrote: > On 2021-06-25 09:58, Michael Gmelin wrote: > > Another problem caused by the lack of jail ownership is that access > > semantics are a bit strange. E.g., a jail based on / can easily list > > (and remove) all memory allocations in the system, while for other > > jails > > it depends. They can stat their own allocations like in: > > > > # posixshmcontrol stat /xyz > > output as expected... > > > > But not list them: > > > > # posixshmcontrol ls > > posixshmcontrol: cannot get kern.ipc.posix_shm_list length: > > Operation not permitted > > > > Probably related to matching the path of the allocation, I didn't > > look into the code. > > That's just a case of the sysctl not being marked as jail-safe. > Looking at the code, it's clear that it needs to be altered when > called from within a jail, but preventing it is definitely not the > right thing. > > > but having something automatic in the OS would be nice. Or being > > able to run `posixshmcontrol -j shmtest ls`. Seems like this would > > be quite some effort though to get it right - also in terms of who > > can access what - right now, it's simply based on the path, which > > also gives > > a lot of flexibility. > > Since access to the shared memory segments themselves is only on file > permissions and pathnames, just making a "posixshmcontrol -j" also > rely on pathnames actually makes sense. > > Put this into a bug report, and I'll take a closer look. Probably two > different bugs for different issues (listing and automatic removal). > Hi Jamie, I *finally* found the time to write the bug reports: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=257554 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=257555 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=257556 I took the liberty to assign them to you. Best, Michael -- Michael Gmelin