Opened 11 months ago

Last modified 11 months ago

#29140 new defect

Tor privdrop on (Open)BSD fails to reclaim capabilities of "User".

Reported by: RatherAnonymousOne Owned by:
Priority: Medium Milestone: Tor: unspecified
Component: Core Tor/Tor Version: Tor: 0.3.4.9
Severity: Normal Keywords: openbsd, bsd, privilege drop, user, torrc, root, disableallswap, capabilities
Cc: Actual Points:
Parent ID: Points:
Reviewer: Sponsor:

Description

As summary states. Should Tor need invocation as superuser it will fail claim the capabilities of the target "User" in torrc. One statement that is therefore affected is e.g. "DisableAllSwap 1" which would either require Tor running as root or raising of superuser capabilities (this was never tested however). Both alternatives are unattractive.

Regarding option with "DisableAllSwap" I will give pretty obvious pointers from your own GitHub repositories:

L1510 @ src/app/config/config.c
L220 @ src/lib/process/setuid.c
L316 @ src/lib/process/setuid.c

And here is kdump format of a ktrace of faulty execution:

28446 tor      CALL  setegid(1000<"user">)
28446 tor      RET   setegid 0
28446 tor      CALL  setgid(1000<"user">)
28446 tor      RET   setgid 0
28446 tor      CALL  setuid(1000<"user">)
28446 tor      RET   setuid 0
28446 tor      CALL  seteuid(1000<"user">)
28446 tor      RET   seteuid 0
28446 tor      CALL  setgid(0<"wheel">)
28446 tor      RET   setgid -1 errno 1 Operation not permitted
28446 tor      CALL  setegid(0<"wheel">)
28446 tor      RET   setegid -1 errno 1 Operation not permitted
28446 tor      CALL  setuid(0<"root">)
28446 tor      RET   setuid -1 errno 1 Operation not permitted
28446 tor      CALL  seteuid(0<"root">)
28446 tor      RET   seteuid -1 errno 1 Operation not permitted

P.S. This applies to 0.3.4.9 but also to 0.3.5.7.

P.P.S. I am sorry I did not take the time to patch this myself yes. For anyone interested in this these are great resources:

man 2 setuid
man 2 seteuid
man 2 setgid
man 2 setegid
man 2 getrlimit
man 2 setrlimit

Child Tickets

Change History (2)

comment:1 in reply to:  description Changed 11 months ago by RatherAnonymousOne

EDIT: Corrected line numbers (these apply to 0.3.5.7).

L1537 @ src/app/config/config.c
L220 @ src/lib/process/setuid.c
L317 @ src/lib/process/setuid.c

Last edited 11 months ago by RatherAnonymousOne (previous) (diff)

comment:2 Changed 11 months ago by nickm

Milestone: Tor: unspecified
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