Messages in this thread | | | Subject | Re: [TOMOYO #7 30/30] Hooks for SAKURA and TOMOYO. | From | Tetsuo Handa <> | Date | Tue, 15 Apr 2008 20:14:41 +0900 |
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Casey Schaufler wrote: > The question of protections on the object named /etc/passwd came > up time and time again. The notion that /etc/passwd could be a > symlink to /home/smalley/heeheehee really gave evaluators the > whillies. As did the chroot environment, where /roots/crispin/etc/passwd > could magicly become /etc/passwd. Why do people continue speaking symlinks and chroots? To avoid the effect of symlinks and chroots, AppArmor and TOMOYO Linux derive pathnames from dentry and vfsmount. If /etc/passwd was a symlink, the derived pathname will be /home/smalley/heeheehee. If accessed from inside a chroot, the derived pathname will be /roots/crispin/etc/passwd.
It is true that namespace may differ between processes, but I think that that is the matter of how to restrict namespace manipulation operations. As I said, a system can't survive if namespace is madly manipulated. To keep the system workable, /bin/ must be the directory for binary programs, /etc/ must be the directory for configuration files, and so on in all namespaces.
It is true that the pathname may change while traversing up the dentry/vfsmount trees. But the change does not occur infinitely. As I said, a system can't survive if files and directories are madly renamed. The possible changes are bounded by the policy.
At least, I want people not to speak symlinks and chroots when talking about AppArmor and TOMOYO Linux.
Regards.
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