Commit 7fc90ec9 authored Jun 30, 2006 by J. Bruce Fields Committed by Linus Torvalds Jun 30, 2006

[PATCH] knfsd: nfsd: call nfsd_setuser() on fh_compose(), fix nfsd4 permissions problem

In the typical v2/v3 case the only new filehandles used as arguments to
operations are filehandles taken directly off the wire, which don't get
dentries until fh_verify() is called.

But in v4 the filehandles that are arguments to operations were often created
by previous operations (putrootfh, lookup, etc.) using fh_compose, which sets
the dentry in the filehandle without calling nfsd_setuser().

This also means that, for example, if filesystem B is mounted on filesystem A,
and filesystem A is exported without root-squashing, then a client can bypass
the rootsquashing on B using a compound that starts at a filehandle in A,
crosses into B using lookups, and then does stuff in B.

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

parent a8cddc5d

fs/nfsd/nfsfh.c

+8 −7

Original line number	Diff line number	Diff line
		@@ -187,13 +187,6 @@ fh_verify(struct svc_rqst rqstp, struct svc_fh fhp, int type, int access)
		goto out;
		}

		/* Set user creds for this exportpoint */
		error = nfsd_setuser(rqstp, exp);
		if (error) {
		error = nfserrno(error);
		goto out;
		}

		/*
		* Look up the dentry using the NFS file handle.
		*/
		@@ -251,6 +244,14 @@ fh_verify(struct svc_rqst rqstp, struct svc_fh fhp, int type, int access)
		}
		cache_get(&exp->h);

		/* Set user creds for this exportpoint; necessary even in the "just
		* checking" case because this may be a filehandle that was created by
		* fh_compose, and that is about to be used in another nfsv4 compound
		* operation */
		error = nfserrno(nfsd_setuser(rqstp, exp));
		if (error)
		goto out;

		error = nfsd_mode_check(rqstp, dentry->d_inode->i_mode, type);
		if (error)
		goto out;