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On Apr 18, 2006, at 21:48:56, Casey Schaufler wrote: > --- James Morris <jmorris@namei.org> wrote: >> With pathnames, there is an unbounded and unknown number of >> effective security policies on the system, as there are an >> unbounded and unknown number of ways of viewing the files via >> pathnames. > > I agree that for traditional DAC and MAC (including the flavors > supported by SELinux) inodes is the only way to go. SELinux is a > traditional Trusted OS architecture and addresses the traditional > Trusted OS issues. Perhaps the SELinux model should be extended to handle (dir-inode, path-entry) pairs. For example, if I want to protect the /etc/shadow file regardless of what tool is used to safely modify it, I would set up security as follows: o Protect the "/" and "/etc" directory inodes as usual under SELinux (with attributes on directory inodes). o Create pairs with (etc_inode,"shadow") and (etc_inode,"gshadow") and apply security attributes to those potentially nonexistent pairs. I'm not terribly familiar with the exact internal semantics of SELinux, but that should provide a 90% solution (it fixes bind mounts and namespaces). The remaining 2 issues are hardlinks and fd- passing. For hardlinks you don't care about other links to that data, you're concerned with protecting a particular filesystem location, not particular contents, so you just need to prevent _new_ hardlinks to a protected (dir_inode, path_elem) pair, which doesn't seem very hard. For fd-passing, I don't know what to do. Perhaps nothing. Anyways, just a few ideas for consideration Cheers, Kyle Moffett - 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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