releases/3.19.7/nfsd4-fix-read-permission-checking.patch

   1 From 6e4891dc289cd191d46ab7ba1dcb29646644f9ca Mon Sep 17 00:00:00 2001
   2 From: "J. Bruce Fields" <bfields@redhat.com>
   3 Date: Fri, 3 Apr 2015 17:19:41 -0400
   4 Subject: nfsd4: fix READ permission checking
   5
   6 From: "J. Bruce Fields" <bfields@redhat.com>
   7
   8 commit 6e4891dc289cd191d46ab7ba1dcb29646644f9ca upstream.
   9
  10 In the case we already have a struct file (derived from a stateid), we
  11 still need to do permission-checking; otherwise an unauthorized user
  12 could gain access to a file by sniffing or guessing somebody else's
  13 stateid.
  14
  15 Fixes: dc97618ddda9 "nfsd4: separate splice and readv cases"
  16 Signed-off-by: J. Bruce Fields <bfields@redhat.com>
  17 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  18
  19 ---
  20  fs/nfsd/nfs4xdr.c |   12 ++++++++----
  21  1 file changed, 8 insertions(+), 4 deletions(-)
  22
  23 --- a/fs/nfsd/nfs4xdr.c
  24 +++ b/fs/nfsd/nfs4xdr.c
  25 @@ -3246,6 +3246,7 @@ nfsd4_encode_read(struct nfsd4_compoundr
  26         unsigned long maxcount;
  27         struct xdr_stream *xdr = &resp->xdr;
  28         struct file *file = read->rd_filp;
  29 +       struct svc_fh *fhp = read->rd_fhp;
  30         int starting_len = xdr->buf->len;
  31         struct raparms *ra;
  32         __be32 *p;
  33 @@ -3269,12 +3270,15 @@ nfsd4_encode_read(struct nfsd4_compoundr
  34         maxcount = min_t(unsigned long, maxcount, (xdr->buf->buflen - xdr->buf->len));
  35         maxcount = min_t(unsigned long, maxcount, read->rd_length);
  36
  37 -       if (!read->rd_filp) {
  38 +       if (read->rd_filp)
  39 +               err = nfsd_permission(resp->rqstp, fhp->fh_export,
  40 +                               fhp->fh_dentry,
  41 +                               NFSD_MAY_READ|NFSD_MAY_OWNER_OVERRIDE);
  42 +       else
  43                 err = nfsd_get_tmp_read_open(resp->rqstp, read->rd_fhp,
  44                                                 &file, &ra);
  45 -               if (err)
  46 -                       goto err_truncate;
  47 -       }
  48 +       if (err)
  49 +               goto err_truncate;
  50
  51         if (file->f_op->splice_read && test_bit(RQ_SPLICE_OK, &resp->rqstp->rq_flags))
  52                 err = nfsd4_encode_splice_read(resp, read, file, maxcount);