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authorPeter Staubach <staubach@redhat.com>2007-05-09 02:34:48 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-05-09 12:30:54 -0700
commitf34b95689d2ce001c157b1604289ff240b4bdee0 (patch)
treee249e166e3c66656ad1b5ac895da6e4c207830e1 /fs/nfsd/nfs3xdr.c
parent8842c9655b2b7f0e8e6c50a773b649e5d8a57678 (diff)
The NFSv2/NFSv3 server does not handle zero length WRITE requests correctly
The NFSv2 and NFSv3 servers do not handle WRITE requests for 0 bytes correctly. The specifications indicate that the server should accept the request, but it should mostly turn into a no-op. Currently, the server will return an XDR decode error, which it should not. Attached is a patch which addresses this issue. It also adds some boundary checking to ensure that the request contains as much data as was requested to be written. It also correctly handles an NFSv3 request which requests to write more data than the server has stated that it is prepared to handle. Previously, there was some support which looked like it should work, but wasn't quite right. Signed-off-by: Peter Staubach <staubach@redhat.com> Acked-by: Neil Brown <neilb@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/nfsd/nfs3xdr.c')
-rw-r--r--fs/nfsd/nfs3xdr.c48
1 files changed, 38 insertions, 10 deletions
diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
index 7e4bb0af24d..43fb360784b 100644
--- a/fs/nfsd/nfs3xdr.c
+++ b/fs/nfsd/nfs3xdr.c
@@ -369,7 +369,7 @@ int
nfs3svc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
struct nfsd3_writeargs *args)
{
- unsigned int len, v, hdr;
+ unsigned int len, v, hdr, dlen;
u32 max_blocksize = svc_max_payload(rqstp);
if (!(p = decode_fh(p, &args->fh))
@@ -379,18 +379,47 @@ nfs3svc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
args->count = ntohl(*p++);
args->stable = ntohl(*p++);
len = args->len = ntohl(*p++);
+ /*
+ * The count must equal the amount of data passed.
+ */
+ if (args->count != args->len)
+ return 0;
+ /*
+ * Check to make sure that we got the right number of
+ * bytes.
+ *
+ * If more than one page was used, then compute the length
+ * of the data in the request as the total size of the
+ * request minus the transport protocol headers minus the
+ * RPC protocol headers minus the NFS protocol fields
+ * already consumed. If the request fits into a single
+ * page, then compete the length of the data as the size
+ * of the NFS portion of the request minus the NFS
+ * protocol fields already consumed.
+ */
hdr = (void*)p - rqstp->rq_arg.head[0].iov_base;
- if (rqstp->rq_arg.len < hdr ||
- rqstp->rq_arg.len - hdr < len)
+ if (rqstp->rq_respages != rqstp->rq_pages + 1) {
+ dlen = rqstp->rq_arg.len -
+ (PAGE_SIZE - rqstp->rq_arg.head[0].iov_len) - hdr;
+ } else {
+ dlen = rqstp->rq_arg.head[0].iov_len - hdr;
+ }
+ /*
+ * 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.
+ */
+ if (dlen != ((len + 3) & ~0x3))
return 0;
+ if (args->count > max_blocksize) {
+ args->count = max_blocksize;
+ len = args->len = max_blocksize;
+ }
rqstp->rq_vec[0].iov_base = (void*)p;
rqstp->rq_vec[0].iov_len = rqstp->rq_arg.head[0].iov_len - hdr;
-
- if (len > max_blocksize)
- len = max_blocksize;
- v= 0;
+ v = 0;
while (len > rqstp->rq_vec[v].iov_len) {
len -= rqstp->rq_vec[v].iov_len;
v++;
@@ -398,9 +427,8 @@ nfs3svc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
rqstp->rq_vec[v].iov_len = PAGE_SIZE;
}
rqstp->rq_vec[v].iov_len = len;
- args->vlen = v+1;
-
- return args->count == args->len && rqstp->rq_vec[0].iov_len > 0;
+ args->vlen = v + 1;
+ return 1;
}
int