Bugtraq mailing list archives
Re: /proc filesystem allows bypassing directory permissions on
From: Martin Rex <Martin.Rex () sap com>
Date: Mon, 2 Nov 2009 18:53:19 +0100 (MET)
Jim Paris wrote:
Therefor it's totally of no influence what you do with the original directory permission. File access has nothing to do with directory permissions...!Right. However the whole point of this discussion is that that is a non-obvious point, there was no other way that the user could have opened that file without the use of /proc.
The actual fallacy of the "problem report" is the flawed assumption about what a link count of 1 tells you. The link count of a files tells you the number of hard links that are persisted within the same filesystem. It is _NOT_ a promise that there are no other means to access the inode of the file. /proc creates a virtual reference to an inode, and since it is virtual (and in a different filesystem) and not persisted in the original filesystem, you will not see it in the link count of the original filesystem. There may be other (virtual) filesystems with similar features. Some Linux distros with Live-CDs (such as Knoppix) use some sort of Overlay filesystem (UNIONFS) which is also purely virtual, none of the changes in the UNIONFS are persited into the underlying filesystem. The inode is part of the administrative data to manage the filesystem space&usage. It is simply inappropriate for an application to draw invalid conclusions from the link count of a files inode. -Martin
Current thread:
- Re: /proc filesystem allows bypassing directory permissions on Martin Rex (Nov 02)
- Re: /proc filesystem allows bypassing directory permissions on Pavel Machek (Nov 02)
- Re: /proc filesystem allows bypassing directory permissions on Gabor Gombas (Nov 03)
- Re: /proc filesystem allows bypassing directory permissions on Martin Rex (Nov 03)
- Re: /proc filesystem allows bypassing directory permissions on Gabor Gombas (Nov 03)
- Re: /proc filesystem allows bypassing directory permissions on psz (Nov 04)
- Re: /proc filesystem allows bypassing directory permissions on Gabor Gombas (Nov 04)
- Re: /proc filesystem allows bypassing directory permissions on Pavel Machek (Nov 04)
- Re: /proc filesystem allows bypassing directory permissions on Pavel Machek (Nov 04)
- Re: /proc filesystem allows bypassing directory permissions on psz (Nov 04)
- Re: /proc filesystem allows bypassing directory permissions on Gabor Gombas (Nov 04)
- Re: /proc filesystem allows bypassing directory permissions on Gabor Gombas (Nov 03)
- Re: /proc filesystem allows bypassing directory permissions on Pavel Machek (Nov 02)