Fwd: Getting path in inode_permission

On Sat, Feb 7, 2015 at 4:21 AM,  [off-list ref] wrote:

On Sat, 07 Feb 2015 01:57:44 +0530, noyb noybee said:

quoted

I need the path lookup data as I need to specifically block inode
loopkups originating from a certain path

Then just make sure the inodes you don't want accessed aren't in the
namespace.

Hint:  "from a certain path" is almost guaranteed to be a security hole,
because all the attacker has to do is cwd() to some different path.  And
there's ../ games that can be played, and so on.

So what are you trying to protect by blocking some lookups? What's the
threat model here?

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
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
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".


Regards,
winged_elite.