Messages in this thread |  | | | Date | Tue, 2 Sep 2008 08:11:27 -0500 | | From | "Serge E. Hallyn" <> | | Subject | Re: (repost) Confirmation of methods for calculating requested pathname. |
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Quoting Kentaro Takeda (takedakn@nttdata.co.jp): > Al, could you answer the following question? > > > The current Linux kernel is not designed to pass vfsmount parameter > that is crucial for pathname-based security including AppArmor and > TOMOYO Linux, to LSM. Though both projects have been proposing > patches to calculate pathname, none of them have been accepted as > you know. > > To find the reason for NACK, we examined past proposals and the > threads. And we came to understand that you oppose accessing vfsmount > inside vfs helper functions. Is our understanding correct? > > If our understanding is correct, we would like to propose a new > method that does not require modifications to vfs helper functions. > Attached patch is a trial of this method. > > vfs helper functions are surrounded by mnt_want_write() and > mnt_drop_write() pairs which receive "struct vfsmount" parameter
I thought Al and others (Stephen?) had made it clear that the thing to do was add new lsm hooks there. So whereas inode_permission takes only an inode and ends up calling security_inode_permission, you would add a security_path_permission() or somesuch before or after the call to inode_permission(), where as you've noted the path is available. You're *close* to doing the right thing by having a helper who is called at the right place catch the vfsmount, but you refuse to send a patch doing exactly what has been suggested.
-serge
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