Re: linux-security-module digest, Vol 1 #45 - 9 msgs

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dwheelerat_private

Jesse Pollard <pollardat_private> said:
...
>This calls for a fileserver (possibly using NFS) that can interpret
>security permissions. For one part, the NFS server daemons need to be
>able to determine whether access can be given (it IS acting on the
>behalf of a file system). Current procedures require the NFS daemon
>to switch UID/GID to the user BEFORE attempting to access the file.
>This is error prone. It introduces a DoS attack (the user is able
>to abort the daemon while it is doing the access).

No, not in Linux, if I understand you correctly.

The canonical method for doing this in Linux is to use
setfsuid(2), a Linux extension.  This forces the process to access
all files as the given user, yet doesn't let the user send signals to
the daemon.  See the setfsuid(2) man page for more details.

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