Gently ping on this. This is easily reproducible, so I am re-attaching
the patch including a new test-case that fails with the current code:
$ tar --xattrs -xf tar
tar: setxattrat: Cannot set 'user.attr' extended attribute for file 'file':
Permission denied
tar: file: Cannot open: Permission denied
tar: Exiting with failure status due to previous errors
Pavel
On Friday, October 9, 2020 1:39:11 PM CET Pavel Raiskup wrote:
> We used to respect the target file mode when pre-creating files in
> set_xattr, so we also pre-created read-only files that we were not able
> to open later for writing. This is now fixed, and we always create the
> file with S_IWUSR.
>
> Fixes the original bug report https://bugzilla.redhat.com/1886540
>
> * src/extract.c (set_xattr): Blindly add S_IWUSR flag to pre-created
> files, to avoid openat failures later.
> ---
> src/extract.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/src/extract.c b/src/extract.c
> index b73a591..2e650ad 100644
> --- a/src/extract.c
> +++ b/src/extract.c
> @@ -865,7 +865,13 @@ set_xattr (char const *file_name, struct tar_stat_info
> const *st,
>
> for (;;)
> {
> - if (!mknodat (chdir_fd, file_name, mode ^ invert_permissions, 0))
> + /* We'll open the file with O_WRONLY later by open_output_file,
> + therefore we need to give us the S_IWUSR bit. If the file was
> + meant to be user-read-only, the permissions will be corrected by
> + the set_stat call. */
> + mode_t initial_mode = mode ^ invert_permissions | S_IWUSR;
> +
> + if (!mknodat (chdir_fd, file_name, initial_mode, 0))
> {
> /* Successfully created file */
> xattrs_xattrs_set (st, file_name, typeflag, 0);
>
>From 42201a0ce560846f770cd5305d04287b13e4bd2b Mon Sep 17 00:00:00 2001
From: Pavel Raiskup <prais...@redhat.com>
Date: Fri, 9 Oct 2020 12:03:22 +0200
Subject: [PATCH] Don't pre-create read-only files with --extract --xattrs
We used to respect the target file mode when pre-creating files in
set_xattr, so we also pre-created read-only files that we were not able
to open later for writing. This is now fixed, and we always create the
file with S_IWUSR.
Fixes the original bug report https://bugzilla.redhat.com/1886540
* src/extract.c (set_xattr): Blindly add S_IWUSR flag to pre-created
files, to avoid openat failures later.
* tests/xattr08.at: New test-case file.
---
src/extract.c | 8 +++++++-
tests/xattr08.at | 45 +++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 52 insertions(+), 1 deletion(-)
create mode 100644 tests/xattr08.at
diff --git a/src/extract.c b/src/extract.c
index 80009a54..358603fe 100644
--- a/src/extract.c
+++ b/src/extract.c
@@ -865,7 +865,13 @@ set_xattr (char const *file_name, struct tar_stat_info const *st,
for (;;)
{
- if (!mknodat (chdir_fd, file_name, mode ^ invert_permissions, 0))
+ /* We'll open the file with O_WRONLY later by open_output_file,
+ therefore we need to give us the S_IWUSR bit. If the file was
+ meant to be user-read-only, the permissions will be corrected by
+ the set_stat call. */
+ mode_t initial_mode = mode ^ invert_permissions | S_IWUSR;
+
+ if (!mknodat (chdir_fd, file_name, initial_mode, 0))
{
/* Successfully created file */
xattrs_xattrs_set (st, file_name, typeflag, 0);
diff --git a/tests/xattr08.at b/tests/xattr08.at
new file mode 100644
index 00000000..0dd3ed34
--- /dev/null
+++ b/tests/xattr08.at
@@ -0,0 +1,45 @@
+# Process this file with autom4te to create testsuite. -*- Autotest -*-
+#
+# Test suite for GNU tar.
+# Copyright 2021 Free Software Foundation, Inc.
+
+# This file is part of GNU tar.
+
+# GNU tar is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+
+# GNU tar is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+# Test description: Test for extracting read-only files with xattrs.
+#
+# Relevant mailing list thread:
+# https://lists.gnu.org/archive/html/bug-tar/2020-10/msg00001.html
+
+AT_SETUP([xattrs: extract read-only files])
+AT_KEYWORDS([xattrs xattr07])
+
+AT_TAR_CHECK([
+AT_XATTRS_PREREQ
+
+touch file
+setfattr -n 'user.attr' -v value file
+chmod 444 file
+tar --xattrs -cf tar file
+rm -f file
+tar --xattrs -xf tar
+getfattr -m user.attr file -d | grep user.attr
+],
+[0],
+[user.attr="value"
+],
+[])
+
+AT_CLEANUP
--
2.29.2
