[PATCH v1 23/42] NFSD: Update the NFSv2 WRITE argument decoder to use struct xdr_stream

Chuck Lever
2021-01-05T15:32:01Z

fs/nfsd/nfsxdr.c | 52 +++++++++++++++++++++-------------------------------
1 file changed, 21 insertions(+), 31 deletions(-)

diff --git a/fs/nfsd/nfsxdr.c b/fs/nfsd/nfsxdr.c
index 1eacaa2c13a9..11d27b219cff 100644
--- a/fs/nfsd/nfsxdr.c
+++ b/fs/nfsd/nfsxdr.c
@@ -266,46 +266,36 @@ nfssvc_decode_readargs(struct svc_rqst *rqstp, __be32 *p)
int
nfssvc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p)
{
+ struct xdr_stream *xdr = &rqstp->rq_arg_stream;
struct nfsd_writeargs *args = rqstp->rq_argp;
- unsigned int len, hdr, dlen;
struct kvec *head = rqstp->rq_arg.head;
+ struct kvec *tail = rqstp->rq_arg.tail;
+ u32 beginoffset, totalcount;
+ size_t remaining;

- p = decode_fh(p, &args->fh);
- if (!p)
+ if (!svcxdr_decode_fhandle(xdr, &args->fh))
return 0;
-
- p++; /* beginoffset */
- args->offset = ntohl(*p++); /* offset */
- p++; /* totalcount */
- len = args->len = ntohl(*p++);
- /*
- * The protocol specifies a maximum of 8192 bytes.
- */
- if (len > NFSSVC_MAXBLKSIZE_V2)
+ /* beginoffset is ignored */
+ if (xdr_stream_decode_u32(xdr, &beginoffset) < 0)
return 0;
-
- /*
- * Check to make sure that we got the right number of
- * bytes.
- */
- hdr = (void*)p - head->iov_base;
- if (hdr > head->iov_len)
+ if (xdr_stream_decode_u32(xdr, &args->offset) < 0)
+ return 0;
+ /* totalcount is ignored */
+ if (xdr_stream_decode_u32(xdr, &totalcount) < 0)
return 0;
- dlen = head->iov_len + rqstp->rq_arg.page_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;
+ if (args->len > NFSSVC_MAXBLKSIZE_V2)
+ 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;
+ args->first.iov_base = xdr->p;
+ args->first.iov_len = head->iov_len - xdr_stream_pos(xdr);

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