On Sat, 07 Feb 2015 07:27:13 +0530, noyb noybee said: > I am trying to enhance the security features of the chroot "jail"(I > know it wasn't built for the purpose). I am trying to prevent access > to files outside the "jail" unless they specify a specific
The right thing to do is design the jail so it *never* references files outside. > passsphrase. Whenever an inode is accessed, inode_persmission is > called. I get the pid of the calling process by current->pid in the > hook and check if it is a child of the original process for which Bzzt! Wrong. Trivially beatable - all I have to do is double-fork, exit the child process, the grandchild gets reparented to PID 1, and your check fails. > chroot was run. If yes + if this process hasn't specified a passphrase > + the path of the inode shows that it is outside the "jail", the > request is blocked. I am also blocking all mounts in the "jail". Plus the whole passphrase thing is probably equally easy to defeat. (Hint - how does the passphrase get passed to the kernel in the first place?)
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