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[tor-bugs] #21022 [Core Tor/Torsocks]: Add several syscalls to src/lib/syscall.c (Torsocks breaks seccomp)
#21022: Add several syscalls to src/lib/syscall.c (Torsocks breaks seccomp)
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Reporter: cypherpunks | Owner: dgoulet
Type: defect | Status: new
Priority: High | Milestone:
Component: Core Tor/Torsocks | Version:
Severity: Normal | Keywords:
Actual Points: | Parent ID:
Points: | Reviewer:
Sponsor: |
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It looks like Torsocks whitelists calls that are allowed to be made via
the glibc `syscall()` function, but unfortunately the whitelist is too
restrictive. For example `seccomp()` is not permitted, and that results in
the syscall being denied (new kernels use that rather than `prctl()` to
enable sandboxes). This results in any program that uses a seccomp sandbox
being unsandboxed when used in combination with Torsocks!
Ideally, `gettimeofday()` and `clock_gettime()` would also be whitelisted,
because they are harmless and calling them as syscalls directly is a handy
way to avoid them being used as vDSOs. The same goes with `fork()`, where
calling it directly is a handy way to avoid having to use the glibc
wrapper, which uses `clone()` instead.
--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/21022>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online
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