From: J. Bruce Fields <[email protected]>
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 <[email protected]>
### Diffstat output
./fs/nfsd/nfsfh.c | 15 ++++++++-------
1 file changed, 8 insertions(+), 7 deletions(-)
diff .prev/fs/nfsd/nfsfh.c ./fs/nfsd/nfsfh.c
--- .prev/fs/nfsd/nfsfh.c 2006-06-27 12:16:27.000000000 +1000
+++ ./fs/nfsd/nfsfh.c 2006-06-27 14:41:52.000000000 +1000
@@ -187,13 +187,6 @@ fh_verify(struct svc_rqst *rqstp, struct
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
}
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;
-
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