Re: [PATCH v1 20/23] NFS: Account for XDR pad of buf->pages

[Olga Kornievskaia <aglo@umich.edu>]

On Fri, Apr 5, 2019 at 3:42 PM Chuck Lever <chuck.lever@oracle.com> wrote:
>
>
>
> > On Apr 5, 2019, at 3:27 PM, Olga Kornievskaia <aglo@umich.edu> wrote:
> >
> > On Fri, Apr 5, 2019 at 3:23 PM Chuck Lever <chuck.lever@oracle.com> wrote:
> >>
> >>
> >>
> >>> On Apr 5, 2019, at 3:17 PM, Olga Kornievskaia <aglo@umich.edu> wrote:
> >>>
> >>> On Fri, Apr 5, 2019 at 1:51 PM Chuck Lever <chuck.lever@oracle.com> wrote:
> >>>>
> >>>>
> >>>>
> >>>>> On Apr 5, 2019, at 1:36 PM, Olga Kornievskaia <aglo@umich.edu> wrote:
> >>>>>
> >>>>> Hi Chuck,
> >>>>>
> >>>>> This patch break ACLs. After applying this patch nfs4_getfacl fails
> >>>>> (it fails within xdr and returns ENOTSUPP). Any ideas why?
> >>>>
> >>>> Possibly the macro that defines the maximum size of the reply
> >>>> is incorrect.
> >>>>
> >>>
> >>> This also breaks FS_LOCATION. I'm going to go on the limb here and say
> >>> that it probably breaks whatever else it modified.
> >>
> >> It modifies READ, READDIR, and READLINK. Are those broken?
> >
> > I don't know how to test READLINK.. but I think READ/READDIR work OK
> > otherwise folks would have noticed it (I gather ACL and FS_LOCATION
> > testing doesn't happen frequently).
>
> I guess I don't have any NFSv4 ACL or FS_LOCATIONS regressions
> tests in my automated unit tests.
>
>
> >>> The question is: can't we just revert it??
> >>
> >> Why not "root cause" it first?
> >
> > I'm trying :-/ I was just fishing to see how important the change was.
>
> Try reverting just this hunk:

That doesn't help. It seems to be this piece that's causing issues
hdrsize += RPC_REPHDRSIZE + req->rq_cred->cr_auth->au_rslack - 1

With this there is an extra byte (in front) in the buffer when (ACL)
operation is decoded.

>
> diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
> index d0fa18d..6d9d5e2 100644
> --- a/fs/nfs/nfs4xdr.c
> +++ b/fs/nfs/nfs4xdr.c
> @@ -284,14 +284,14 @@ static int decode_layoutget(struct xdr_stream *xdr, struct rpc_rqst *req,
> #define decode_delegreturn_maxsz (op_decode_hdr_maxsz)
> #define encode_getacl_maxsz     (encode_getattr_maxsz)
> #define decode_getacl_maxsz     (op_decode_hdr_maxsz + \
> -                                nfs4_fattr_bitmap_maxsz + 1)
> +                                nfs4_fattr_bitmap_maxsz + 1 + 1)
> #define encode_setacl_maxsz     (op_encode_hdr_maxsz + \
>                                  encode_stateid_maxsz + 3)
> #define decode_setacl_maxsz     (decode_setattr_maxsz)
> #define encode_fs_locations_maxsz \
>                                 (encode_getattr_maxsz)
> #define decode_fs_locations_maxsz \
> -                               (0)
> +                               (1)
> #define encode_secinfo_maxsz    (op_encode_hdr_maxsz + nfs4_name_maxsz)
> #define decode_secinfo_maxsz    (op_decode_hdr_maxsz + 1 + ((NFS_MAX_SECFLAVORS * (16 + GSS_OID_MAX_LEN)) / 4))
>
>
> >>>>> On Mon, Feb 11, 2019 at 11:25 AM Chuck Lever <chuck.lever@oracle.com> wrote:
> >>>>>>
> >>>>>> Certain NFS results (eg. READLINK) might expect a data payload that
> >>>>>> is not an exact multiple of 4 bytes. In this case, XDR encoding
> >>>>>> is required to pad that payload so its length on the wire is a
> >>>>>> multiple of 4 bytes. The constants that define the maximum size of
> >>>>>> each NFS result do not appear to account for this extra word.
> >>>>>>
> >>>>>> In each case where the data payload is to be received into pages:
> >>>>>>
> >>>>>> - 1 word is added to the size of the receive buffer allocated by
> >>>>>> call_allocate
> >>>>>>
> >>>>>> - rpc_inline_rcv_pages subtracts 1 word from @hdrsize so that the
> >>>>>> extra buffer space falls into the rcv_buf's tail iovec
> >>>>>>
> >>>>>> - If buf->pagelen is word-aligned, an XDR pad is not needed and
> >>>>>> is thus removed from the tail
> >>>>>>
> >>>>>> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
> >>>>>> ---
> >>>>>> fs/nfs/nfs2xdr.c  |    6 +++---
> >>>>>> fs/nfs/nfs3xdr.c  |   10 +++++-----
> >>>>>> fs/nfs/nfs4xdr.c  |   15 ++++++++-------
> >>>>>> net/sunrpc/clnt.c |    6 +++++-
> >>>>>> net/sunrpc/xdr.c  |    2 ++
> >>>>>> 5 files changed, 23 insertions(+), 16 deletions(-)
> >>>>>>
> >>>>>> diff --git a/fs/nfs/nfs2xdr.c b/fs/nfs/nfs2xdr.c
> >>>>>> index 1dcd0fe..a7ed29d 100644
> >>>>>> --- a/fs/nfs/nfs2xdr.c
> >>>>>> +++ b/fs/nfs/nfs2xdr.c
> >>>>>> @@ -56,11 +56,11 @@
> >>>>>>
> >>>>>> #define NFS_attrstat_sz                (1+NFS_fattr_sz)
> >>>>>> #define NFS_diropres_sz                (1+NFS_fhandle_sz+NFS_fattr_sz)
> >>>>>> -#define NFS_readlinkres_sz     (2)
> >>>>>> -#define NFS_readres_sz         (1+NFS_fattr_sz+1)
> >>>>>> +#define NFS_readlinkres_sz     (2+1)
> >>>>>> +#define NFS_readres_sz         (1+NFS_fattr_sz+1+1)
> >>>>>> #define NFS_writeres_sz         (NFS_attrstat_sz)
> >>>>>> #define NFS_stat_sz            (1)
> >>>>>> -#define NFS_readdirres_sz      (1)
> >>>>>> +#define NFS_readdirres_sz      (1+1)
> >>>>>> #define NFS_statfsres_sz       (1+NFS_info_sz)
> >>>>>>
> >>>>>> static int nfs_stat_to_errno(enum nfs_stat);
> >>>>>> diff --git a/fs/nfs/nfs3xdr.c b/fs/nfs/nfs3xdr.c
> >>>>>> index a54dcf4..110358f 100644
> >>>>>> --- a/fs/nfs/nfs3xdr.c
> >>>>>> +++ b/fs/nfs/nfs3xdr.c
> >>>>>> @@ -69,13 +69,13 @@
> >>>>>> #define NFS3_removeres_sz      (NFS3_setattrres_sz)
> >>>>>> #define NFS3_lookupres_sz      (1+NFS3_fh_sz+(2 * NFS3_post_op_attr_sz))
> >>>>>> #define NFS3_accessres_sz      (1+NFS3_post_op_attr_sz+1)
> >>>>>> -#define NFS3_readlinkres_sz    (1+NFS3_post_op_attr_sz+1)
> >>>>>> -#define NFS3_readres_sz                (1+NFS3_post_op_attr_sz+3)
> >>>>>> +#define NFS3_readlinkres_sz    (1+NFS3_post_op_attr_sz+1+1)
> >>>>>> +#define NFS3_readres_sz                (1+NFS3_post_op_attr_sz+3+1)
> >>>>>> #define NFS3_writeres_sz       (1+NFS3_wcc_data_sz+4)
> >>>>>> #define NFS3_createres_sz      (1+NFS3_fh_sz+NFS3_post_op_attr_sz+NFS3_wcc_data_sz)
> >>>>>> #define NFS3_renameres_sz      (1+(2 * NFS3_wcc_data_sz))
> >>>>>> #define NFS3_linkres_sz                (1+NFS3_post_op_attr_sz+NFS3_wcc_data_sz)
> >>>>>> -#define NFS3_readdirres_sz     (1+NFS3_post_op_attr_sz+2)
> >>>>>> +#define NFS3_readdirres_sz     (1+NFS3_post_op_attr_sz+2+1)
> >>>>>> #define NFS3_fsstatres_sz      (1+NFS3_post_op_attr_sz+13)
> >>>>>> #define NFS3_fsinfores_sz      (1+NFS3_post_op_attr_sz+12)
> >>>>>> #define NFS3_pathconfres_sz    (1+NFS3_post_op_attr_sz+6)
> >>>>>> @@ -85,7 +85,7 @@
> >>>>>> #define ACL3_setaclargs_sz     (NFS3_fh_sz+1+ \
> >>>>>>                              XDR_QUADLEN(NFS_ACL_INLINE_BUFSIZE))
> >>>>>> #define ACL3_getaclres_sz      (1+NFS3_post_op_attr_sz+1+ \
> >>>>>> -                               XDR_QUADLEN(NFS_ACL_INLINE_BUFSIZE))
> >>>>>> +                               XDR_QUADLEN(NFS_ACL_INLINE_BUFSIZE)+1)
> >>>>>> #define ACL3_setaclres_sz      (1+NFS3_post_op_attr_sz)
> >>>>>>
> >>>>>> static int nfs3_stat_to_errno(enum nfs_stat);
> >>>>>> @@ -1629,7 +1629,7 @@ static int nfs3_xdr_dec_read3res(struct rpc_rqst *req, struct xdr_stream *xdr,
> >>>>>>      result->op_status = status;
> >>>>>>      if (status != NFS3_OK)
> >>>>>>              goto out_status;
> >>>>>> -       result->replen = 3 + ((xdr_stream_pos(xdr) - pos) >> 2);
> >>>>>> +       result->replen = 4 + ((xdr_stream_pos(xdr) - pos) >> 2);
> >>>>>>      error = decode_read3resok(xdr, result);
> >>>>>> out:
> >>>>>>      return error;
> >>>>>> diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
> >>>>>> index d0fa18d..6d9d5e2 100644
> >>>>>> --- a/fs/nfs/nfs4xdr.c
> >>>>>> +++ b/fs/nfs/nfs4xdr.c
> >>>>>> @@ -215,14 +215,14 @@ static int decode_layoutget(struct xdr_stream *xdr, struct rpc_rqst *req,
> >>>>>>                               nfs4_fattr_bitmap_maxsz)
> >>>>>> #define encode_read_maxsz      (op_encode_hdr_maxsz + \
> >>>>>>                               encode_stateid_maxsz + 3)
> >>>>>> -#define decode_read_maxsz      (op_decode_hdr_maxsz + 2)
> >>>>>> +#define decode_read_maxsz      (op_decode_hdr_maxsz + 2 + 1)
> >>>>>> #define encode_readdir_maxsz   (op_encode_hdr_maxsz + \
> >>>>>>                               2 + encode_verifier_maxsz + 5 + \
> >>>>>>                              nfs4_label_maxsz)
> >>>>>> #define decode_readdir_maxsz   (op_decode_hdr_maxsz + \
> >>>>>> -                                decode_verifier_maxsz)
> >>>>>> +                                decode_verifier_maxsz + 1)
> >>>>>> #define encode_readlink_maxsz  (op_encode_hdr_maxsz)
> >>>>>> -#define decode_readlink_maxsz  (op_decode_hdr_maxsz + 1)
> >>>>>> +#define decode_readlink_maxsz  (op_decode_hdr_maxsz + 1 + 1)
> >>>>>> #define encode_write_maxsz     (op_encode_hdr_maxsz + \
> >>>>>>                               encode_stateid_maxsz + 4)
> >>>>>> #define decode_write_maxsz     (op_decode_hdr_maxsz + \
> >>>>>> @@ -284,14 +284,14 @@ static int decode_layoutget(struct xdr_stream *xdr, struct rpc_rqst *req,
> >>>>>> #define decode_delegreturn_maxsz (op_decode_hdr_maxsz)
> >>>>>> #define encode_getacl_maxsz    (encode_getattr_maxsz)
> >>>>>> #define decode_getacl_maxsz    (op_decode_hdr_maxsz + \
> >>>>>> -                                nfs4_fattr_bitmap_maxsz + 1)
> >>>>>> +                                nfs4_fattr_bitmap_maxsz + 1 + 1)
> >>>>>> #define encode_setacl_maxsz    (op_encode_hdr_maxsz + \
> >>>>>>                               encode_stateid_maxsz + 3)
> >>>>>> #define decode_setacl_maxsz    (decode_setattr_maxsz)
> >>>>>> #define encode_fs_locations_maxsz \
> >>>>>>                              (encode_getattr_maxsz)
> >>>>>> #define decode_fs_locations_maxsz \
> >>>>>> -                               (0)
> >>>>>> +                               (1)
> >>>>>> #define encode_secinfo_maxsz   (op_encode_hdr_maxsz + nfs4_name_maxsz)
> >>>>>> #define decode_secinfo_maxsz   (op_decode_hdr_maxsz + 1 + ((NFS_MAX_SECFLAVORS * (16 + GSS_OID_MAX_LEN)) / 4))
> >>>>>>
> >>>>>> @@ -392,12 +392,13 @@ static int decode_layoutget(struct xdr_stream *xdr, struct rpc_rqst *req,
> >>>>>>                              1 /* opaque devaddr4 length */ + \
> >>>>>>                                /* devaddr4 payload is read into page */ \
> >>>>>>                              1 /* notification bitmap length */ + \
> >>>>>> -                               1 /* notification bitmap, word 0 */)
> >>>>>> +                               1 /* notification bitmap, word 0 */ + \
> >>>>>> +                               1 /* possible XDR padding */)
> >>>>>> #define encode_layoutget_maxsz (op_encode_hdr_maxsz + 10 + \
> >>>>>>                              encode_stateid_maxsz)
> >>>>>> #define decode_layoutget_maxsz (op_decode_hdr_maxsz + 8 + \
> >>>>>>                              decode_stateid_maxsz + \
> >>>>>> -                               XDR_QUADLEN(PNFS_LAYOUT_MAXSIZE))
> >>>>>> +                               XDR_QUADLEN(PNFS_LAYOUT_MAXSIZE) + 1)
> >>>>>> #define encode_layoutcommit_maxsz (op_encode_hdr_maxsz +          \
> >>>>>>                              2 /* offset */ + \
> >>>>>>                              2 /* length */ + \
> >>>>>> diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
> >>>>>> index f780605..4ea38b0 100644
> >>>>>> --- a/net/sunrpc/clnt.c
> >>>>>> +++ b/net/sunrpc/clnt.c
> >>>>>> @@ -1177,7 +1177,11 @@ void rpc_prepare_reply_pages(struct rpc_rqst *req, struct page **pages,
> >>>>>>                           unsigned int base, unsigned int len,
> >>>>>>                           unsigned int hdrsize)
> >>>>>> {
> >>>>>> -       hdrsize += RPC_REPHDRSIZE + req->rq_cred->cr_auth->au_rslack;
> >>>>>> +       /* Subtract one to force an extra word of buffer space for the
> >>>>>> +        * payload's XDR pad to fall into the rcv_buf's tail iovec.
> >>>>>> +        */
> >>>>>> +       hdrsize += RPC_REPHDRSIZE + req->rq_cred->cr_auth->au_rslack - 1;
> >>>>>> +
> >>>>>>      xdr_inline_pages(&req->rq_rcv_buf, hdrsize << 2, pages, base, len);
> >>>>>>      trace_rpc_reply_pages(req);
> >>>>>> }
> >>>>>> diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
> >>>>>> index 7cca515..aa8177d 100644
> >>>>>> --- a/net/sunrpc/xdr.c
> >>>>>> +++ b/net/sunrpc/xdr.c
> >>>>>> @@ -189,6 +189,8 @@ __be32 *xdr_encode_opaque(__be32 *p, const void *ptr, unsigned int nbytes)
> >>>>>>
> >>>>>>      tail->iov_base = buf + offset;
> >>>>>>      tail->iov_len = buflen - offset;
> >>>>>> +       if ((xdr->page_len & 3) == 0)
> >>>>>> +               tail->iov_len -= sizeof(__be32);
> >>>>>>
> >>>>>>      xdr->buflen += len;
> >>>>>> }
> >>>>>>
> >>>>
> >>>> --
> >>>> Chuck Lever
> >>
> >> --
> >> Chuck Lever
>
> --
> Chuck Lever
>
>
>