From 0b74885e81b90d6ab4890b195dce99ca9109fe59 Mon Sep 17 00:00:00 2001 From: Paul Eggert Date: Fri, 26 Aug 2022 15:23:23 -0500 Subject: Fix bug with -x --xattr read-only files MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Problem reported by Kevin Raymond in: https://bugzilla.redhat.com/show_bug.cgi?id=1886540 * src/extract.c (open_output_file): If we already created the empty file, do not open with O_EXCL, or with O_CREAT or O_TRUNC for that matter. Instead, use only O_NOFOLLOW to avoid some races. When estimating current mode, use openflag & O_EXCL rather than overwriting_old_files. (extract_file): Also invert S_IWUSR if it’s not set. * tests/xattr08.at: New test. * tests/Makefile.am, tests/testsuite.at: Add it. --- src/extract.c | 31 +++++++++++++++---------------- tests/Makefile.am | 1 + tests/testsuite.at | 1 + tests/xattr08.at | 41 +++++++++++++++++++++++++++++++++++++++++ 4 files changed, 58 insertions(+), 16 deletions(-) create mode 100644 tests/xattr08.at diff --git a/src/extract.c b/src/extract.c index 2813c961..c1f5731b 100644 --- a/src/extract.c +++ b/src/extract.c @@ -1189,14 +1189,12 @@ open_output_file (char const *file_name, int typeflag, mode_t mode, int fd; bool overwriting_old_files = old_files_option == OVERWRITE_OLD_FILES; int openflag = (O_WRONLY | O_BINARY | O_CLOEXEC | O_NOCTTY | O_NONBLOCK - | O_CREAT - | (overwriting_old_files - ? O_TRUNC | (dereference_option ? 0 : O_NOFOLLOW) - : O_EXCL)); - - /* File might be created in set_xattr. So clear O_EXCL to avoid open() fail */ - if (file_created) - openflag = openflag & ~O_EXCL; + | (file_created + ? O_NOFOLLOW + : (O_CREAT + | (overwriting_old_files + ? O_TRUNC | (dereference_option ? 0 : O_NOFOLLOW) + : O_EXCL)))); if (typeflag == CONTTYPE) { @@ -1227,7 +1225,12 @@ open_output_file (char const *file_name, int typeflag, mode_t mode, fd = openat (chdir_fd, file_name, openflag, mode); if (0 <= fd) { - if (overwriting_old_files) + if (openflag & O_EXCL) + { + *current_mode = mode & ~ current_umask; + *current_mode_mask = MODE_RWX; + } + else { struct stat st; if (fstat (fd, &st) != 0) @@ -1246,11 +1249,6 @@ open_output_file (char const *file_name, int typeflag, mode_t mode, *current_mode = st.st_mode; *current_mode_mask = ALL_MODE_BITS; } - else - { - *current_mode = mode & ~ current_umask; - *current_mode_mask = MODE_RWX; - } } return fd; @@ -1268,8 +1266,9 @@ extract_file (char *file_name, int typeflag) bool interdir_made = false; mode_t mode = (current_stat_info.stat.st_mode & MODE_RWX & ~ (0 < same_owner_option ? S_IRWXG | S_IRWXO : 0)); - mode_t invert_permissions = 0 < same_owner_option ? mode & (S_IRWXG | S_IRWXO) - : 0; + mode_t invert_permissions + = ((0 < same_owner_option ? mode & (S_IRWXG | S_IRWXO) : 0) + | ((mode & S_IWUSR) ^ S_IWUSR)); mode_t current_mode = 0; mode_t current_mode_mask = 0; diff --git a/tests/Makefile.am b/tests/Makefile.am index eff8a3bf..a0ce690b 100644 --- a/tests/Makefile.am +++ b/tests/Makefile.am @@ -275,6 +275,7 @@ TESTSUITE_AT = \ xattr05.at\ xattr06.at\ xattr07.at\ + xattr08.at\ acls01.at\ acls02.at\ acls03.at\ diff --git a/tests/testsuite.at b/tests/testsuite.at index 0769e71b..a99cdeee 100644 --- a/tests/testsuite.at +++ b/tests/testsuite.at @@ -502,6 +502,7 @@ m4_include([xattr04.at]) m4_include([xattr05.at]) m4_include([xattr06.at]) m4_include([xattr07.at]) +m4_include([xattr08.at]) m4_include([acls01.at]) m4_include([acls02.at]) diff --git a/tests/xattr08.at b/tests/xattr08.at new file mode 100644 index 00000000..2beef235 --- /dev/null +++ b/tests/xattr08.at @@ -0,0 +1,41 @@ +# Process this file with autom4te to create testsuite. -*- Autotest -*- +# +# Test suite for GNU tar. +# Copyright 2022 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 . +# +# Test description: +# Test read-only files can be extracted with --xattr. +# Per report: +# https://lists.gnu.org/r/bug-tar/2020-10/msg00001.html + +AT_SETUP([xattrs: xattrs and read-only files]) +AT_KEYWORDS([xattrs xattr08]) + +AT_TAR_CHECK([ +AT_XATTRS_PREREQ +mkdir dir dir2 +genfile --file dir/file + +setfattr -n user.test -v OurDirValue dir/file +chmod a-w dir/file + +tar --xattrs -C dir -cf archive.tar file +tar --xattrs -C dir2 -xf archive.tar +]) + +AT_CLEANUP -- cgit v1.2.1