[PATCH v1 07/42] NFSD: Update WRITE3arg decoder to use struct xdr_stream

Chuck Lever
2021-01-05T15:31:09Z

As part of the update, open code that sanity-checks the size of the
data payload against the length of the RPC Call message has to be
re-implemented to use xdr_stream infrastructure.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
fs/nfsd/nfs3xdr.c | 51 ++++++++++++++++++++-------------------------------
1 file changed, 20 insertions(+), 31 deletions(-)

diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
index ff98eae5db81..0aafb096de91 100644
--- a/fs/nfsd/nfs3xdr.c
+++ b/fs/nfsd/nfs3xdr.c
@@ -405,52 +405,41 @@ nfs3svc_decode_readargs(struct svc_rqst *rqstp, __be32 *p)
int
nfs3svc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p)
{
+ struct xdr_stream *xdr = &rqstp->rq_arg_stream;
struct nfsd3_writeargs *args = rqstp->rq_argp;
- unsigned int len, hdr, dlen;
u32 max_blocksize = svc_max_payload(rqstp);
struct kvec *head = rqstp->rq_arg.head;
struct kvec *tail = rqstp->rq_arg.tail;
+ size_t remaining;

- p = decode_fh(p, &args->fh);
- if (!p)
+ if (!svcxdr_decode_nfs_fh3(xdr, &args->fh))
return 0;
- p = xdr_decode_hyper(p, &args->offset);
-
- args->count = ntohl(*p++);
- args->stable = ntohl(*p++);
- len = args->len = ntohl(*p++);
- if ((void *)p > head->iov_base + head->iov_len)
+ if (xdr_stream_decode_u64(xdr, &args->offset) < 0)
return 0;
- /*
- * The count must equal the amount of data passed.
- */
- if (args->count != args->len)
+ if (xdr_stream_decode_u32(xdr, &args->count) < 0)
+ return 0;
+ if (xdr_stream_decode_u32(xdr, &args->stable) < 0)
return 0;

- /*
- * Check to make sure that we got the right number of
- * bytes.
- */
- hdr = (void*)p - head->iov_base;
- dlen = head->iov_len + rqstp->rq_arg.page_len + tail->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.
- * 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)
+ /* opaque data */
+ if (xdr_stream_decode_u32(xdr, &args->len) < 0)
return 0;

+ /* request sanity */
+ if (args->count != args->len)
+ return 0;
+ remaining = head->iov_len + rqstp->rq_arg.page_len + tail->iov_len;
+ remaining -= xdr_stream_pos(xdr);
+ if (remaining < xdr_align_size(args->len))
+ return 0;
if (args->count > max_blocksize) {
args->count = max_blocksize;
- len = args->len = max_blocksize;
+ args->len = max_blocksize;
}

- args->first.iov_base = (void *)p;
- args->first.iov_len = head->iov_len - hdr;
+ args->first.iov_base = xdr->p;
+ args->first.iov_len = head->iov_len - xdr_stream_pos(xdr);
+
return 1;
}