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

Chuck Lever
2021-01-22T19:40:02Z

> On Jan 22, 2021, at 1:47 PM, J. Bruce Fields <bfields@fieldses.org> wrote:
>
> On Tue, Jan 05, 2021 at 10:30:18AM -0500, Chuck Lever wrote:
>> 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.
>
> I'm having a little trouble parsing that. Did you mean "write code"?

The WRITE payload size sanity-checking code has to be re-implemented.

> --b.
>
>>
>> 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;
>> }
>>
>>

--
Chuck Lever