knfsd: Allow NFSv2/3 WRITE calls to succeed when krb5i etc is used.

When RPCSEC/GSS and krb5i is used, requests are padded, typically to a multiple
of 8 bytes.  This can make the request look slightly longer than it
really is.

As of

	f34b95689d2ce001c "The NFSv2/NFSv3 server does not handle zero
		length WRITE request correctly",

the xdr decode routines for NFSv2 and NFSv3 reject requests that aren't
the right length, so krb5i (for example) WRITE requests can get lost.

This patch relaxes the appropriate test and enhances the related comment.

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Cc: Peter Staubach <staubach@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
index 2d116d2298f8e3aec23982bc04795dd9daf69ca2..f917fd25858af81a4edaf712fffa3480ee3a8e6b 100644 (file)
--- a/fs/nfsd/nfs3xdr.c
+++ b/fs/nfsd/nfs3xdr.c
@@ -388,8 +388,11 @@ nfs3svc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
         * Round the length of the data which was specified up to
         * the next multiple of XDR units and then compare that
         * against the length which was actually received.
+        * Note that when RPCSEC/GSS (for example) is used, the
+        * data buffer can be padded so dlen might be larger
+        * than required.  It must never be smaller.
         */
-       if (dlen != XDR_QUADLEN(len)*4)
+       if (dlen < XDR_QUADLEN(len)*4)
                return 0;
 
        if (args->count > max_blocksize) {

diff --git a/fs/nfsd/nfsxdr.c b/fs/nfsd/nfsxdr.c
index 986f9b32083c655f792ada9476d3658a71bb37d7..b86e3658a0af10ebce825e260ee1fc5fd879f367 100644 (file)
--- a/fs/nfsd/nfsxdr.c
+++ b/fs/nfsd/nfsxdr.c
@@ -313,8 +313,11 @@ nfssvc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
         * Round the length of the data which was specified up to
         * the next multiple of XDR units and then compare that
         * against the length which was actually received.
+        * Note that when RPCSEC/GSS (for example) is used, the
+        * data buffer can be padded so dlen might be larger
+        * than required.  It must never be smaller.
         */
-       if (dlen != XDR_QUADLEN(len)*4)
+       if (dlen < XDR_QUADLEN(len)*4)
                return 0;
 
        rqstp->rq_vec[0].iov_base = (void*)p;