Firewall Wizards mailing list archives
Re: chroot useful?
From: mcnabb () argus-systems com (Paul McNabb)
Date: Fri, 14 Nov 1997 16:47:28 -0600
Date: Fri, 14 Nov 1997 02:54:59 +0000 From: "Steven M. Bellovin" <smb () research att com> >That is, chroot could be run to define the root point such that critical >files are inaccessible, and then the untrusted application would >subsequently be launched. Is this not correct? That was precisely my point -- that this opinion is not correct. There are numerous ways for root to break out of a chroot() "jail"; the simplest is to do mknod() to create new special device files for the real disks, and mount new file systems on those devices. Many other variants are possible as well.
Unless, again, your system allows you to prevent root from doing a mknod(). The use of capabilities and/or privileges can get around these mechanisms that make chroot less secure. On Decaf'ed systems, processes running in capability mode can't make the mknod() system call, even if the uid is 0. paul --------------------------------------------------------- Paul McNabb Argus Systems Group, Inc. Vice President and CTO 1809 Woodfield Drive mcnabb () argus-systems com Savoy, IL 61874 USA TEL 217-355-6308 FAX 217-355-1433 "Securing the Future" ---------------------------------------------------------
Current thread:
- Re: chroot useful?, (continued)
- Re: chroot useful? Steven M. Bellovin (Nov 13)
- Re: chroot useful? C Matthew Curtin (Nov 21)
- Re: chroot useful? Steven M. Bellovin (Nov 13)
- Re: chroot useful? Paul McNabb (Nov 12)
- Re: chroot useful? Douglas R. Steinbaum (Nov 13)
- Re: chroot useful? Darren Reed (Nov 14)
- Re: chroot useful? Steven M. Bellovin (Nov 14)
- Re: chroot useful? Aleph One (Nov 14)
- Re: chroot useful? Steven M. Bellovin (Nov 15)
- Re: chroot useful? Bernhard Schneck (Nov 14)
- Re: chroot useful? Paul McNabb (Nov 14)
- Re: chroot useful? Paul McNabb (Nov 14)
- Re: chroot useful? Paul McNabb (Nov 14)
- Re: chroot useful? Anton J Aylward (Nov 15)
- Re: chroot useful? Steven M. Bellovin (Nov 16)
- Re: chroot useful? Anton J Aylward (Nov 15)
- Re: chroot useful? Darren Reed (Nov 16)
- Re: chroot useful? Anton J Aylward (Nov 16)
- Re: chroot useful? Anton J Aylward (Nov 16)
- Re: chroot useful? Darren Reed (Nov 16)
- Re: chroot useful? Rick Murphy (Nov 17)
- Hardening, (was Re: chroot useful?) Marcus J. Ranum (Nov 20)
- Re: chroot useful? Darren Reed (Nov 16)