Messages in this thread | | | Date | Tue, 23 Apr 2002 14:02:39 +0200 | From | Alex Riesen <> | Subject | Re: [SECURITY] FDs 0, 1, 2 for SUID/SGID programs |
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On Mon, Apr 22, 2002 at 12:18:19PM -0700, Chris Wright wrote: > * Florian Weimer (Weimer@CERT.Uni-Stuttgart.DE) wrote: > > http://www.pine.nl/advisories/pine-cert-20020401.html probably affects > > Linux, too (if a SUID/SGID program is invoked with FD 2 closed, error > > messages might be written to a file opened by the program ). > > AFAIK, the standards clearly specify behaviour wrt. open file descriptors > and clone-on-exec file descriptors across execve(). However, there
that is close-on-exec. Different semantics.
F_GETFD Read the close-on-exec flag. If the FD_CLOEXEC bit is 0, the file will remain open across exec, otherwise it will be closed.
> is nothing specified when it comes to closed file descpriptors across > execve(), notably FD's 0, 1 and 2 are certainly not required to be open > across an execve() of a SUID/SGID applictaion. One could argue that > SUID/SGID apps that trust the file descriptors they inherit across exec() > are buggy. > > Having said that, there are a number of implementations of this type > of protection for the linux kernel stemming from the Openwall project. > If you are interested, see: > > http://www.openwall.com (CONFIG_SECURE_FD_0_1_2) > http://lsm.immunix.org (CONFIG_OWLSM_FD) > http://grsecurity.net (CONFIG_GRKERNSEC_FD) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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