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tar-fix-no-overwrite-dir.patch
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File tar-fix-no-overwrite-dir.patch of Package tar
From 14d8fc718f0c872274b90991ee634b0cd8e1a6f0 Mon Sep 17 00:00:00 2001 From: Sergey Poznyakoff <gray@gnu.org> Date: Sat, 8 Feb 2020 13:01:47 +0200 Subject: Fix the --no-overwrite-dir option Given this option, tar failed to preserve permissions of empty directories and to create files under directories owned by the current user that did not have the S_IWUSR bit set. * src/extract.c (fd_chmod): Rename to fd_i_chmod. (fd_chmod): New function. (safe_dir_mode): New function. (extract_dir): Special handling for existing directories in --no-overwrite-dir mode. * tests/extrac23.at: New file. * tests/Makefile.am: Add new test case. * tests/testsuite.at: Likewise. --- src/extract.c | 128 +++++++++++++++++++++++++++++++++++------------------ tests/Makefile.am | 1 + tests/extrac23.at | 58 ++++++++++++++++++++++++ tests/testsuite.at | 1 + 4 files changed, 146 insertions(+), 42 deletions(-) create mode 100644 tests/extrac23.at Index: tar-1.27.1/src/extract.c =================================================================== --- tar-1.27.1.orig/src/extract.c +++ tar-1.27.1/src/extract.c @@ -195,7 +195,7 @@ extr_init (void) /* Use fchmod if possible, fchmodat otherwise. */ static int -fd_chmod (int fd, char const *file, mode_t mode, int atflag) +fd_i_chmod (int fd, char const *file, mode_t mode, int atflag) { if (0 <= fd) { @@ -206,6 +206,42 @@ fd_chmod (int fd, char const *file, mode return fchmodat (chdir_fd, file, mode, atflag); } +/* A version of fd_i_chmod which gracefully handles several common error + conditions. Additional argument TYPEFLAG is the type of file in tar + notation. + */ +static int +fd_chmod(int fd, char const *file_name, int mode, int atflag, int typeflag) +{ + int chmod_errno = fd_i_chmod (fd, file_name, mode, atflag) == 0 ? 0 : errno; + + /* On Solaris, chmod may fail if we don't have PRIV_ALL, because + setuid-root files would otherwise be a backdoor. See + http://opensolaris.org/jive/thread.jspa?threadID=95826 + (2009-09-03). */ + if (chmod_errno == EPERM && (mode & S_ISUID) + && priv_set_restore_linkdir () == 0) + { + chmod_errno = fd_i_chmod (fd, file_name, mode, atflag) == 0 ? 0 : errno; + priv_set_remove_linkdir (); + } + + /* Linux fchmodat does not support AT_SYMLINK_NOFOLLOW, and + returns ENOTSUP even when operating on non-symlinks, try + again with the flag disabled if it does not appear to be + supported and if the file is not a symlink. This + introduces a race, alas. */ + if (atflag && typeflag != SYMTYPE && ! implemented (chmod_errno)) + chmod_errno = fd_i_chmod (fd, file_name, mode, 0) == 0 ? 0 : errno; + + if (chmod_errno && (typeflag != SYMTYPE || implemented (chmod_errno))) + { + errno = chmod_errno; + return -1; + } + return 0; +} + /* Use fchown if possible, fchownat otherwise. */ static int fd_chown (int fd, char const *file, uid_t uid, gid_t gid, int atflag) @@ -260,35 +296,8 @@ set_mode (char const *file_name, if (current_mode != mode) { - int chmod_errno = - fd_chmod (fd, file_name, mode, atflag) == 0 ? 0 : errno; - - /* On Solaris, chmod may fail if we don't have PRIV_ALL, because - setuid-root files would otherwise be a backdoor. See - http://opensolaris.org/jive/thread.jspa?threadID=95826 - (2009-09-03). */ - if (chmod_errno == EPERM && (mode & S_ISUID) - && priv_set_restore_linkdir () == 0) - { - chmod_errno = - fd_chmod (fd, file_name, mode, atflag) == 0 ? 0 : errno; - priv_set_remove_linkdir (); - } - - /* Linux fchmodat does not support AT_SYMLINK_NOFOLLOW, and - returns ENOTSUP even when operating on non-symlinks, try - again with the flag disabled if it does not appear to be - supported and if the file is not a symlink. This - introduces a race, alas. */ - if (atflag && typeflag != SYMTYPE && ! implemented (chmod_errno)) - chmod_errno = fd_chmod (fd, file_name, mode, 0) == 0 ? 0 : errno; - - if (chmod_errno - && (typeflag != SYMTYPE || implemented (chmod_errno))) - { - errno = chmod_errno; - chmod_error_details (file_name, mode); - } + if (fd_chmod (fd, file_name, mode, atflag, typeflag)) + chmod_error_details (file_name, mode); } } } @@ -882,6 +891,26 @@ is_directory_link (char const *file_name && S_ISDIR (st->st_mode)); } +/* Given struct stat of a directory (or directory member) whose ownership + or permissions of will be restored later, return the temporary permissions + for that directory, sufficiently restrictive so that in the meantime + processes owned by other users do not inadvertently create files under this + directory that inherit the wrong owner, group, or permissions from the + directory. + + If not root, though, make the directory writeable and searchable at first, + so that files can be created under it. +*/ +static inline int +safe_dir_mode (struct stat const *st) +{ + return ((st->st_mode + & (0 < same_owner_option || 0 < same_permissions_option + ? S_IRWXU + : MODE_RWX)) + | (we_are_root ? 0 : MODE_WXUSR)); +} + /* Extractor functions for various member types */ static int @@ -911,18 +940,7 @@ extract_dir (char *file_name, int typefl else if (typeflag == GNUTYPE_DUMPDIR) skip_member (); - /* If ownership or permissions will be restored later, create the - directory with restrictive permissions at first, so that in the - meantime processes owned by other users do not inadvertently - create files under this directory that inherit the wrong owner, - group, or permissions from the directory. If not root, though, - make the directory writeable and searchable at first, so that - files can be created under it. */ - mode = ((current_stat_info.stat.st_mode - & (0 < same_owner_option || 0 < same_permissions_option - ? S_IRWXU - : MODE_RWX)) - | (we_are_root ? 0 : MODE_WXUSR)); + mode = safe_dir_mode (¤t_stat_info.stat); for (;;) { @@ -938,6 +956,7 @@ extract_dir (char *file_name, int typefl if (errno == EEXIST && (interdir_made || keep_directory_symlink_option + || old_files_option == NO_OVERWRITE_DIR_OLD_FILES || old_files_option == DEFAULT_OLD_FILES || old_files_option == OVERWRITE_OLD_FILES)) { @@ -961,6 +980,31 @@ extract_dir (char *file_name, int typefl repair_delayed_set_stat (file_name, &st); return 0; } + else if (old_files_option == NO_OVERWRITE_DIR_OLD_FILES) + { + /* Temporarily change the directory mode to a safe + value, to be able to create files in it, should + the need be. + */ + mode = safe_dir_mode (&st); + status = fd_chmod(-1, file_name, mode, + AT_SYMLINK_NOFOLLOW, DIRTYPE); + if (status == 0) + { + /* Store the actual directory mode, to be restored + later. + */ + current_stat_info.stat = st; + current_mode = mode & ~ current_umask; + current_mode_mask = MODE_RWX; + atflag = AT_SYMLINK_NOFOLLOW; + break; + } + else + { + chmod_error_details (file_name, mode); + } + } break; } } Index: tar-1.27.1/tests/Makefile.am =================================================================== --- tar-1.27.1.orig/tests/Makefile.am +++ tar-1.27.1/tests/Makefile.am @@ -102,6 +102,7 @@ TESTSUITE_AT = \ extrac17.at\ extrac18.at\ extrac19.at\ + extrac23.at\ filerem01.at\ filerem02.at\ gzip.at\ Index: tar-1.27.1/tests/extrac23.at =================================================================== --- /dev/null +++ tar-1.27.1/tests/extrac23.at @@ -0,0 +1,58 @@ +# Test suite for GNU tar. -*- Autotest -*- +# Copyright 2020 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/>. +AT_SETUP([--no-overwrite-dir]) +AT_KEYWORDS([extract extrac23 no-overwrite-dir]) + +# Description: Implementation of the --no-overwrite-dir option was flawed in +# tar versions up to 1.32.90. This option is intended to preserve metadata +# of existing directories. In fact it worked only for non-empty directories. +# Moreover, if the actual directory was owned by the user tar runs as and the +# S_IWUSR bit was not set in its actual permissions, tar failed to create files +# in it. +# +# Reported by: Michael Kaufmann <mail@michael-kaufmann.ch> +# References: <20200207112934.Horde.anXzYhAj2CHiwUrw5CuT0G-@webmail.michael-kaufmann.ch>, +# https://lists.gnu.org/archive/html/bug-tar/2020-02/msg00003.html + +AT_TAR_CHECK([ +# Test if the directory permissions are restored properly. +mkdir dir +chmod 755 dir +tar cf a.tar dir +chmod 777 dir +tar -xf a.tar --no-overwrite-dir +genfile --stat=mode.777 dir + +# Test if temprorary permissions are set correctly to allow the owner +# to write to the directory. +genfile --file dir/file +tar cf a.tar dir +rm dir/file +chmod 400 dir +tar -xf a.tar --no-overwrite-dir +genfile --stat=mode.777 dir +chmod 700 dir +find dir +], +[0], +[777 +400 +dir +dir/file +]) +AT_CLEANUP Index: tar-1.27.1/tests/testsuite.at =================================================================== --- tar-1.27.1.orig/tests/testsuite.at +++ tar-1.27.1/tests/testsuite.at @@ -276,6 +276,7 @@ m4_include([extrac16.at]) m4_include([extrac17.at]) m4_include([extrac18.at]) m4_include([extrac19.at]) +m4_include([extrac23.at]) m4_include([backup01.at]) AT_BANNER([Volume label operations])
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