nfsd: avoid permission checks on EXCLUSIVE_CREATE replay

With NFSv4, if we create a file then open it we explicit avoid checking
the permissions on the file during the open because the fact that we
created it ensures we should be allow to open it (the create and the
open should appear to be a single operation).

However if the reply to an EXCLUSIVE create gets lots and the client
resends the create, the current code will perform the permission check -
because it doesn't realise that it did the open already..

This patch should fix this.

Note that I haven't actually seen this cause a problem.  I was just
looking at the code trying to figure out a different EXCLUSIVE open
related issue, and this looked wrong.

(Fix confirmed with pynfs 4.0 test OPEN4--bfields)

Cc: stable@kernel.org
Signed-off-by: NeilBrown <neilb@suse.de>
[bfields: use OWNER_OVERRIDE and update for 4.1]
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 87d24e5f3ca438076da4bdbdc34123c02248990e..1a0b1fdb5ad3b46891e932138fb660ab33173b92 100644 (file)
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -195,6 +195,7 @@ static __be32
 do_open_lookup(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nfsd4_open *open)
 {
        struct svc_fh *resfh;
+       int accmode;
        __be32 status;
 
        resfh = kmalloc(sizeof(struct svc_fh), GFP_KERNEL);
@@ -254,9 +255,10 @@ do_open_lookup(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nfsd4_o
        /* set reply cache */
        fh_copy_shallow(&open->op_openowner->oo_owner.so_replay.rp_openfh,
                        &resfh->fh_handle);
-       if (!open->op_created)
-               status = do_open_permission(rqstp, resfh, open,
-                                           NFSD_MAY_NOP);
+       accmode = NFSD_MAY_NOP;
+       if (open->op_created)
+               accmode |= NFSD_MAY_OWNER_OVERRIDE;
+       status = do_open_permission(rqstp, resfh, open, accmode);
        set_change_info(&open->op_cinfo, current_fh);
        fh_dup2(current_fh, resfh);
 out:

diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index b584205b25b41d66558f5ae8408242edb24fb670..0ef9b6b410a2b89071e6d50b7b34c3f5457da434 100644 (file)
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1471,13 +1471,19 @@ do_nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
                case NFS3_CREATE_EXCLUSIVE:
                        if (   dchild->d_inode->i_mtime.tv_sec == v_mtime
                            && dchild->d_inode->i_atime.tv_sec == v_atime
-                           && dchild->d_inode->i_size  == 0 )
+                           && dchild->d_inode->i_size  == 0 ) {
+                               if (created)
+                                       *created = 1;
                                break;
+                       }
                case NFS4_CREATE_EXCLUSIVE4_1:
                        if (   dchild->d_inode->i_mtime.tv_sec == v_mtime
                            && dchild->d_inode->i_atime.tv_sec == v_atime
-                           && dchild->d_inode->i_size  == 0 )
+                           && dchild->d_inode->i_size  == 0 ) {
+                               if (created)
+                                       *created = 1;
                                goto set_attr;
+                       }
                         /* fallthru */
                case NFS3_CREATE_GUARDED:
                        err = nfserr_exist;