Description: Do not follow symlinks when processing the fixup list
Published as CVE-2021-31566
Origin: upstream, https://github.com/libarchive/libarchive/commit/b41daecb5ccb4c8e3b2c53fd6147109fc12c3043
Bug-Debian: https://bugs.debian.org/1001990
Author: Martin Matuska <martin@matuska.org>
Last-Update: 2021-12-20
CVE: CVE-2021-31566
Upstream-Status: Backport [http://deb.debian.org/debian/pool/main/liba/libarchive/libarchive_3.4.3-2+deb11u1.debian.tar.xz]
Signed-off-by: Ranjitsinh Rathod <ranjitsinh.rathod@kpit.com>
--- a/Makefile.am
+++ b/Makefile.am
@@ -556,6 +556,7 @@
libarchive/test/test_write_disk.c \
libarchive/test/test_write_disk_appledouble.c \
libarchive/test/test_write_disk_failures.c \
+ libarchive/test/test_write_disk_fixup.c \
libarchive/test/test_write_disk_hardlink.c \
libarchive/test/test_write_disk_hfs_compression.c \
libarchive/test/test_write_disk_lookup.c \
--- a/libarchive/archive_write_disk_posix.c
+++ b/libarchive/archive_write_disk_posix.c
@@ -2461,6 +2461,7 @@
{
struct archive_write_disk *a = (struct archive_write_disk *)_a;
struct fixup_entry *next, *p;
+ struct stat st;
int fd, ret;
archive_check_magic(&a->archive, ARCHIVE_WRITE_DISK_MAGIC,
@@ -2478,6 +2479,20 @@
(TODO_TIMES | TODO_MODE_BASE | TODO_ACLS | TODO_FFLAGS)) {
fd = open(p->name,
O_WRONLY | O_BINARY | O_NOFOLLOW | O_CLOEXEC);
+ if (fd == -1) {
+ /* If we cannot lstat, skip entry */
+ if (lstat(p->name, &st) != 0)
+ goto skip_fixup_entry;
+ /*
+ * If we deal with a symbolic link, mark
+ * it in the fixup mode to ensure no
+ * modifications are made to its target.
+ */
+ if (S_ISLNK(st.st_mode)) {
+ p->mode &= ~S_IFMT;
+ p->mode |= S_IFLNK;
+ }
+ }
}
if (p->fixup & TODO_TIMES) {
set_times(a, fd, p->mode, p->name,
@@ -2492,7 +2507,12 @@
fchmod(fd, p->mode);
else
#endif
- chmod(p->name, p->mode);
+#ifdef HAVE_LCHMOD
+ lchmod(p->name, p->mode);
+#else
+ if (!S_ISLNK(p->mode))
+ chmod(p->name, p->mode);
+#endif
}
if (p->fixup & TODO_ACLS)
archive_write_disk_set_acls(&a->archive, fd,
@@ -2503,6 +2523,7 @@
if (p->fixup & TODO_MAC_METADATA)
set_mac_metadata(a, p->name, p->mac_metadata,
p->mac_metadata_size);
+skip_fixup_entry:
next = p->next;
archive_acl_clear(&p->acl);
free(p->mac_metadata);
@@ -2643,6 +2664,7 @@
fe->next = a->fixup_list;
a->fixup_list = fe;
fe->fixup = 0;
+ fe->mode = 0;
fe->name = strdup(pathname);
return (fe);
}
--- a/libarchive/test/CMakeLists.txt
+++ b/libarchive/test/CMakeLists.txt
@@ -208,6 +208,7 @@
test_write_disk.c
test_write_disk_appledouble.c
test_write_disk_failures.c
+ test_write_disk_fixup.c
test_write_disk_hardlink.c
test_write_disk_hfs_compression.c
test_write_disk_lookup.c
--- /dev/null
+++ b/libarchive/test/test_write_disk_fixup.c
@@ -0,0 +1,77 @@
+/*-
+ * Copyright (c) 2021 Martin Matuska
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+#include "test.h"
+
+/*
+ * Test fixup entries don't follow symlinks
+ */
+DEFINE_TEST(test_write_disk_fixup)
+{
+ struct archive *ad;
+ struct archive_entry *ae;
+ int r;
+
+ if (!canSymlink()) {
+ skipping("Symlinks not supported");
+ return;
+ }
+
+ /* Write entries to disk. */
+ assert((ad = archive_write_disk_new()) != NULL);
+
+ /*
+ * Create a file
+ */
+ assertMakeFile("victim", 0600, "a");
+
+ /*
+ * Create a directory and a symlink with the same name
+ */
+
+ /* Directory: dir */
+ assert((ae = archive_entry_new()) != NULL);
+ archive_entry_copy_pathname(ae, "dir");
+ archive_entry_set_mode(ae, AE_IFDIR | 0606);
+ assertEqualIntA(ad, 0, archive_write_header(ad, ae));
+ assertEqualIntA(ad, 0, archive_write_finish_entry(ad));
+ archive_entry_free(ae);
+
+ /* Symbolic Link: dir -> foo */
+ assert((ae = archive_entry_new()) != NULL);
+ archive_entry_copy_pathname(ae, "dir");
+ archive_entry_set_mode(ae, AE_IFLNK | 0777);
+ archive_entry_set_size(ae, 0);
+ archive_entry_copy_symlink(ae, "victim");
+ assertEqualIntA(ad, 0, r = archive_write_header(ad, ae));
+ if (r >= ARCHIVE_WARN)
+ assertEqualIntA(ad, 0, archive_write_finish_entry(ad));
+ archive_entry_free(ae);
+
+ assertEqualInt(ARCHIVE_OK, archive_write_free(ad));
+
+ /* Test the entries on disk. */
+ assertIsSymlink("dir", "victim", 0);
+ assertFileMode("victim", 0600);
+}