nfsd: permit unauthenticated stat of export root
RFC 2623 section 2.3.2 permits the server to bypass gss authentication
checks for certain operations that a client may perform when mounting.
In the case of a client that doesn't have some form of credentials
available to it on boot, this allows it to perform the mount unattended.
(Presumably real file access won't be needed until a user with
credentials logs in.)
Being slightly more lenient allows lots of old clients to access
krb5-only exports, with the only loss being a small amount of
information leaked about the root directory of the export.
This affects only v2 and v3; v4 still requires authentication for all
access.
Thanks to Peter Staubach testing against a Solaris client, which
suggesting addition of v3 getattr, to the list, and to Trond for noting
that doing so exposes no additional information.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Cc: Peter Staubach <staubach@redhat.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
diff --git a/fs/nfsd/nfs3proc.c b/fs/nfsd/nfs3proc.c
index 4d617ea..9dbd2eb 100644
--- a/fs/nfsd/nfs3proc.c
+++ b/fs/nfsd/nfs3proc.c
@@ -63,7 +63,8 @@
SVCFH_fmt(&argp->fh));
fh_copy(&resp->fh, &argp->fh);
- nfserr = fh_verify(rqstp, &resp->fh, 0, NFSD_MAY_NOP);
+ nfserr = fh_verify(rqstp, &resp->fh, 0,
+ NFSD_MAY_NOP | NFSD_MAY_BYPASS_GSS_ON_ROOT);
if (nfserr)
RETURN_STATUS(nfserr);
@@ -530,7 +531,7 @@
dprintk("nfsd: FSSTAT(3) %s\n",
SVCFH_fmt(&argp->fh));
- nfserr = nfsd_statfs(rqstp, &argp->fh, &resp->stats);
+ nfserr = nfsd_statfs(rqstp, &argp->fh, &resp->stats, 0);
fh_put(&argp->fh);
RETURN_STATUS(nfserr);
}
@@ -558,7 +559,8 @@
resp->f_maxfilesize = ~(u32) 0;
resp->f_properties = NFS3_FSF_DEFAULT;
- nfserr = fh_verify(rqstp, &argp->fh, 0, NFSD_MAY_NOP);
+ nfserr = fh_verify(rqstp, &argp->fh, 0,
+ NFSD_MAY_NOP | NFSD_MAY_BYPASS_GSS_ON_ROOT);
/* Check special features of the file system. May request
* different read/write sizes for file systems known to have