#3910: +RTS options introduce a security problem for, e.g., setuid binaries
------------------------------------------+---------------------------------
Reporter: andersk | Owner: simonmar
Type: bug | Status: closed
Priority: normal | Milestone: 7.0.2
Component: Runtime System | Version: 7.1
Resolution: fixed | Keywords:
Testcase: | Blockedby:
Difficulty: | Os: Unknown/Multiple
Blocking: | Architecture: Unknown/Multiple
Failure: Incorrect result at runtime |
------------------------------------------+---------------------------------
Comment(by duncan@…):
commit 8c7ad0bd5bf1e7f62f44784cc889e8ee585b8d08
{{{
Author: Duncan Coutts <[email protected]>
Date: Thu Oct 27 13:26:15 2011 +0100
Change what +RTS options are available by default
Ticket #3910 originally pointed out that the RTS options are a
potential
security problem. For example the -t -s or -S flags can be used to
overwrite files. This would be bad in the context of CGI scripts or
setuid binaries. So we introduced a system where +RTS processing is
more
or less disabled unless you pass the -rtsopts flag at link time.
This scheme is safe enough but it also really annoies users. They have
to use -rtsopts in many circumstances: with -threaded to use -N, with
-eventlog to use -l, with -prof to use any of the profiling flags.
Many
users just set -rtsopts globally or in project .cabal files. Apart
from
annoying users it reduces security because it means that deployed
binaries will have all RTS options enabled rather than just profiling
ones.
This patch relaxes the set of RTS options that are available in the
default -rtsopts=some case. For "deployment" ways like vanilla and
-threaded we remain quite conservative. Only --info -? --help are
allowed for vanilla. For -threaded, -N and -N<x> are allowed with a
check that x <= num cpus.
For "developer" ways like -debug, -eventlog, -prof, we allow all the
options that are special to that way. Some of these allow writing
files,
but the file written is not directly under the control of the
attacker.
For the setuid case (where the attacker would have control over binary
name, current dir, local symlinks etc) we check if the process is
running setuid/setgid and refuse all RTS option processing. Users
would
need to use -rtsopts=all in this case.
We are making the assumption that developers will not deploy binaries
built in the -debug, -eventlog, -prof ways. And even if they do, the
damage should be limited to DOS, information disclosure and writing
files like <progname>.eventlog, not arbitrary files.
rts/RtsFlags.c | 131
+++++++++++++++++++++++++++++++++++++++++++++++---------
1 files changed, 110 insertions(+), 21 deletions(-)
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3910#comment:13>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
_______________________________________________
Glasgow-haskell-bugs mailing list
[email protected]
http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
