[PATCH v1 19/42] NFSD: Update the SYMLINK3args decoder to use struct xdr_stream

Chuck Lever
2021-01-05T15:32:18Z

Similar to the WRITE decoder, code that checks the sanity of the
payload size is re-wired to work with xdr_stream infrastructure.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
fs/nfsd/nfs3xdr.c | 29 ++++++++++++++++-------------
1 file changed, 16 insertions(+), 13 deletions(-)

diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
index 45975fdb033e..e599d1481b2d 100644
--- a/fs/nfsd/nfs3xdr.c
+++ b/fs/nfsd/nfs3xdr.c
@@ -616,25 +616,28 @@ nfs3svc_decode_mkdirargs(struct svc_rqst *rqstp, __be32 *p)
int
nfs3svc_decode_symlinkargs(struct svc_rqst *rqstp, __be32 *p)
{
+ struct xdr_stream *xdr = &rqstp->rq_arg_stream;
struct nfsd3_symlinkargs *args = rqstp->rq_argp;
- char *base = (char *)p;
- size_t dlen;
+ struct kvec *head = rqstp->rq_arg.head;
+ struct kvec *tail = rqstp->rq_arg.tail;
+ size_t remaining;

- if (!(p = decode_fh(p, &args->ffh)) ||
- !(p = decode_filename(p, &args->fname, &args->flen)))
+ if (!svcxdr_decode_diropargs3(xdr, &args->ffh, &args->fname, &args->flen))
+ return 0;
+ if (!svcxdr_decode_sattr3(rqstp, xdr, &args->attrs))
+ return 0;
+ if (xdr_stream_decode_u32(xdr, &args->tlen) < 0)
return 0;
- p = decode_sattr3(p, &args->attrs, nfsd_user_namespace(rqstp));

- args->tlen = ntohl(*p++);
+ /* request sanity */
+ remaining = head->iov_len + rqstp->rq_arg.page_len + tail->iov_len;
+ remaining -= xdr_stream_pos(xdr);
+ if (remaining < xdr_align_size(args->tlen))
+ return 0;

- args->first.iov_base = p;
- args->first.iov_len = rqstp->rq_arg.head[0].iov_len;
- args->first.iov_len -= (char *)p - base;
+ args->first.iov_base = xdr->p;
+ args->first.iov_len = head->iov_len - xdr_stream_pos(xdr);

- dlen = args->first.iov_len + rqstp->rq_arg.page_len +
- rqstp->rq_arg.tail[0].iov_len;
- if (dlen < XDR_QUADLEN(args->tlen) << 2)
- return 0;
return 1;
}