[PATCH] NFS: Ensure we always update inode->i_mode when doing O_EXCL creates

When the client performs an exclusive create and opens the file for writing,
a Netapp filer will first create the file using the mode 01777. It does this
since an NFSv3/v4 exclusive create cannot immediately set the mode bits.
The 01777 mode then gets put into the inode->i_mode. After the file creation
is successful, we then do a setattr to change the mode to the correct value
(as per the NFS spec).

The problem is that nfs_refresh_inode() no longer updates inode->i_mode, so
the latter retains the 01777 mode. A bit later, the VFS notices this, and calls
remove_suid(). This of course now resets the file mode to inode->i_mode & 0777.
Hey presto, the file mode on the server is now magically changed to 0777. Duh...

Fixes http://bugzilla.linux-nfs.org/show_bug.cgi?id=32

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/nfs/inode.c

@@ -814,29 +814,40 @@ nfs_setattr(struct dentry *dentry, struct iattr *attr)
 		nfs_wb_all(inode);
 	}
 	error = NFS_PROTO(inode)->setattr(dentry, &fattr, attr);
-	if (error == 0) {
+	if (error == 0)
 		nfs_refresh_inode(inode, &fattr);
+	nfs_end_data_update(inode);
+	unlock_kernel();
+	return error;
+}
+
+/**
+ * nfs_setattr_update_inode - Update inode metadata after a setattr call.
+ * @inode: pointer to struct inode
+ * @attr: pointer to struct iattr
+ *
+ * Note: we do this in the *proc.c in order to ensure that
+ *       it works for things like exclusive creates too.
+ */
+void nfs_setattr_update_inode(struct inode *inode, struct iattr *attr)
+{
+	if ((attr->ia_valid & (ATTR_MODE|ATTR_UID|ATTR_GID)) != 0) {
 		if ((attr->ia_valid & ATTR_MODE) != 0) {
-			int mode;
-			mode = inode->i_mode & ~S_IALLUGO;
-			mode |= attr->ia_mode & S_IALLUGO;
+			int mode = attr->ia_mode & S_IALLUGO;
+			mode |= inode->i_mode & ~S_IALLUGO;
 			inode->i_mode = mode;
 		}
 		if ((attr->ia_valid & ATTR_UID) != 0)
 			inode->i_uid = attr->ia_uid;
 		if ((attr->ia_valid & ATTR_GID) != 0)
 			inode->i_gid = attr->ia_gid;
+		NFS_FLAGS(inode) |= NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
+	}
 	if ((attr->ia_valid & ATTR_SIZE) != 0) {
 		inode->i_size = attr->ia_size;
 		vmtruncate(inode, attr->ia_size);
 	}
 }
-	if ((attr->ia_valid & (ATTR_MODE|ATTR_UID|ATTR_GID)) != 0)
-		NFS_FLAGS(inode) |= NFS_INO_INVALID_ACCESS|NFS_INO_INVALID_ACL;
-	nfs_end_data_update(inode);
-	unlock_kernel();
-	return error;
-}
 
 /*
  * Wait for the inode to get unlocked.

fs/nfs/nfs3proc.c

@@ -120,6 +120,8 @@ nfs3_proc_setattr(struct dentry *dentry, struct nfs_fattr *fattr,
 	dprintk("NFS call  setattr\n");
 	fattr->valid = 0;
 	status = rpc_call(NFS_CLIENT(inode), NFS3PROC_SETATTR, &arg, fattr, 0);
+	if (status == 0)
+		nfs_setattr_update_inode(inode, sattr);
 	dprintk("NFS reply setattr: %d\n", status);
 	return status;
 }
@@ -370,6 +372,8 @@ again:
 		 * not sure this buys us anything (and I'd have
 		 * to revamp the NFSv3 XDR code) */
 		status = nfs3_proc_setattr(dentry, &fattr, sattr);
+		if (status == 0)
+			nfs_setattr_update_inode(dentry->d_inode, sattr);
 		nfs_refresh_inode(dentry->d_inode, &fattr);
 		dprintk("NFS reply setattr (post-create): %d\n", status);
 	}

fs/nfs/nfs4proc.c

@@ -753,6 +753,7 @@ static int _nfs4_do_setattr(struct nfs_server *server, struct nfs_fattr *fattr,
                 .rpc_argp       = &arg,
                 .rpc_resp       = &res,
         };
+	int status;
 
         fattr->valid = 0;
 
@@ -762,7 +763,8 @@ static int _nfs4_do_setattr(struct nfs_server *server, struct nfs_fattr *fattr,
 	} else
 		memcpy(&arg.stateid, &zero_stateid, sizeof(arg.stateid));
 
-	return rpc_call_sync(server->client, &msg, 0);
+	status = rpc_call_sync(server->client, &msg, 0);
+	return status;
 }
 
 static int nfs4_do_setattr(struct nfs_server *server, struct nfs_fattr *fattr,
@@ -1145,6 +1147,8 @@ nfs4_proc_setattr(struct dentry *dentry, struct nfs_fattr *fattr,
 
 	status = nfs4_do_setattr(NFS_SERVER(inode), fattr,
 			NFS_FH(inode), sattr, state);
+	if (status == 0)
+		nfs_setattr_update_inode(inode, sattr);
 	if (state != NULL)
 		nfs4_close_state(state, FMODE_WRITE);
 	put_rpccred(cred);
@@ -1449,8 +1453,10 @@ nfs4_proc_create(struct inode *dir, struct dentry *dentry, struct iattr *sattr,
 		struct nfs_fattr fattr;
 		status = nfs4_do_setattr(NFS_SERVER(dir), &fattr,
 		                     NFS_FH(state->inode), sattr, state);
-		if (status == 0)
+		if (status == 0) {
+			nfs_setattr_update_inode(state->inode, sattr);
 			goto out;
+		}
 	} else if (flags != 0)
 		goto out;
 	nfs4_close_state(state, flags);

fs/nfs/proc.c

@@ -114,6 +114,8 @@ nfs_proc_setattr(struct dentry *dentry, struct nfs_fattr *fattr,
 	dprintk("NFS call  setattr\n");
 	fattr->valid = 0;
 	status = rpc_call(NFS_CLIENT(inode), NFSPROC_SETATTR, &arg, fattr, 0);
+	if (status == 0)
+		nfs_setattr_update_inode(inode, sattr);
 	dprintk("NFS reply setattr: %d\n", status);
 	return status;
 }

include/linux/nfs_fs.h

@@ -292,6 +292,7 @@ extern int nfs_revalidate_inode(struct nfs_server *server, struct inode *inode);
 extern int __nfs_revalidate_inode(struct nfs_server *, struct inode *);
 extern void nfs_revalidate_mapping(struct inode *inode, struct address_space *mapping);
 extern int nfs_setattr(struct dentry *, struct iattr *);
+extern void nfs_setattr_update_inode(struct inode *inode, struct iattr *attr);
 extern void nfs_begin_attr_update(struct inode *);
 extern void nfs_end_attr_update(struct inode *);
 extern void nfs_begin_data_update(struct inode *);