Re: NFS and setuid programs fails on 2.1

Alan Cox (alan@lxorguk.ukuu.org.uk)
Wed, 12 Aug 1998 16:26:40 +0100 (BST)

> The 2.1 kernel has a problem with setuid programs that try to write a file
> on NFS mounted fs. It has nothing to do with root access to NFS fs. It's
> really a bug and it has been introduced in the 2.1 kernel.

Does 2.1.115ac1/ac2 also show this problem. They do have a couple of NFS
permission fixes in that ought to work

> the file as a different user. Normal UNIX behaviour allows this, and it
> works on 2.0.x kernels, as well as other unices. It also works fine if you
> write a non-NFS file.

First NFS isnt a posix compliant file system. Because its pseudo stateless
the current uid not the opening uid is applied to requests. The kernel is
fairly smart - it maps permission errors to a retry with real uid/gid. The
older code however onyl caught one of the error codes involved

Alan

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