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

[Olga Kornievskaia <aglo@umich.edu>]

On Mon, Apr 8, 2019 at 11:26 AM Olga Kornievskaia <aglo@umich.edu> wrote:
>
> On Mon, Apr 8, 2019 at 11:21 AM Olga Kornievskaia <aglo@umich.edu> wrote:
> >
> > On Mon, Apr 8, 2019 at 10:43 AM Chuck Lever <chuck.lever@oracle.com> wrote:
> > >
> > >
> > >
> > > > On Apr 8, 2019, at 10:36 AM, Olga Kornievskaia <aglo@umich.edu> wrote:
> > > >
> > > > 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.
> > >
> > > How do you know there isn't a latent bug in the getfacl decoder?
> >
> > I don't. All I know is that it passed tests before and now it doesn't.
>
> Also this bug will have to be in both getfacl and fs_location code.
> What they both share is xd_enter_page() code that now with new
> semantics makes the buffer point to the wrong place.
>
> > > How are you reproducing this issue? I can try it here later today.
> >
> > The issue was found running xfstest nfs/001. However, you don't need
> > that: (1) mount (2) nfs4_getfacl <file>
> >
> > To understand a patch, does it fix a problem with READLINK or is the
> > an optimization?

So this "fixes" it but this don't look really good.

diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index cfcabc3..f2a5553 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c

@@ -5280,6 +5280,7 @@ static int decode_getacl(struct xdr_stream *xdr,
struct rpc_rqst *req,
  goto out;
  xdr_enter_page(xdr, xdr->buf->page_len);
+ xdr->p++;

  /* Calculate the offset of the page data */
  pg_offset = xdr->buf->head[0].iov_len;
@@ -6949,6 +6950,7 @@ static int nfs4_xdr_dec_fs_locations(struct rpc_rqst *req,
  goto out;
  if (res->migration) {
  xdr_enter_page(xdr, PAGE_SIZE);
+ xdr->p++;
  status = decode_getfattr_generic(xdr,
  &res->fs_locations->fattr,
  NULL, res->fs_locations,
@@ -6962,6 +6964,7 @@ static int nfs4_xdr_dec_fs_locations(struct rpc_rqst *req,
  if (status)
  goto out;
  xdr_enter_page(xdr, PAGE_SIZE);
+ xdr->p++;
  status = decode_getfattr_generic(xdr,
  &res->fs_locations->fattr,
  NULL, res->fs_locations,


> >
> > >
> > >
> > > >> 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
> > >
> > > --
> > > Chuck Lever
> > >
> > >
> > >