[git commit] unzip: prevent attacks via malicious filenames
Denys Vlasenko
vda.linux at googlemail.com
Tue Feb 10 00:30:43 UTC 2015
commit: http://git.busybox.net/busybox/commit/?id=8c06bc6ba14949d945eff0abcabab885f1ef7680
branch: http://git.busybox.net/busybox/commit/?id=refs/heads/master
Signed-off-by: Denys Vlasenko <vda.linux at googlemail.com>
---
archival/libarchive/Kbuild.src | 5 ++-
archival/libarchive/get_header_tar.c | 30 ----------------------------
archival/libarchive/unsafe_prefix.c | 36 ++++++++++++++++++++++++++++++++++
archival/unzip.c | 35 ++++++++++++++++++++++----------
4 files changed, 63 insertions(+), 43 deletions(-)
diff --git a/archival/libarchive/Kbuild.src b/archival/libarchive/Kbuild.src
index 7e89e9e..b7faaf7 100644
--- a/archival/libarchive/Kbuild.src
+++ b/archival/libarchive/Kbuild.src
@@ -30,6 +30,7 @@ COMMON_FILES:= \
DPKG_FILES:= \
unpack_ar_archive.o \
filter_accept_list_reassign.o \
+ unsafe_prefix.o \
get_header_ar.o \
get_header_tar.o \
get_header_tar_gz.o \
@@ -44,7 +45,7 @@ lib-$(CONFIG_DPKG_DEB) += $(DPKG_FILES)
lib-$(CONFIG_AR) += get_header_ar.o unpack_ar_archive.o
lib-$(CONFIG_CPIO) += get_header_cpio.o
-lib-$(CONFIG_TAR) += get_header_tar.o
+lib-$(CONFIG_TAR) += get_header_tar.o unsafe_prefix.o
lib-$(CONFIG_FEATURE_TAR_TO_COMMAND) += data_extract_to_command.o
lib-$(CONFIG_LZOP) += lzo1x_1.o lzo1x_1o.o lzo1x_d.o
lib-$(CONFIG_LZOP_COMPR_HIGH) += lzo1x_9x.o
@@ -53,7 +54,7 @@ lib-$(CONFIG_UNLZMA) += open_transformer.o decompress_unlzma.
lib-$(CONFIG_UNXZ) += open_transformer.o decompress_unxz.o
lib-$(CONFIG_GUNZIP) += open_transformer.o decompress_gunzip.o
lib-$(CONFIG_UNCOMPRESS) += open_transformer.o decompress_uncompress.o
-lib-$(CONFIG_UNZIP) += open_transformer.o decompress_gunzip.o
+lib-$(CONFIG_UNZIP) += open_transformer.o decompress_gunzip.o unsafe_prefix.o
lib-$(CONFIG_RPM2CPIO) += open_transformer.o decompress_gunzip.o get_header_cpio.o
lib-$(CONFIG_RPM) += open_transformer.o decompress_gunzip.o get_header_cpio.o
diff --git a/archival/libarchive/get_header_tar.c b/archival/libarchive/get_header_tar.c
index ba43bb0..0c663fb 100644
--- a/archival/libarchive/get_header_tar.c
+++ b/archival/libarchive/get_header_tar.c
@@ -17,36 +17,6 @@
typedef uint32_t aliased_uint32_t FIX_ALIASING;
typedef off_t aliased_off_t FIX_ALIASING;
-
-const char* FAST_FUNC strip_unsafe_prefix(const char *str)
-{
- const char *cp = str;
- while (1) {
- char *cp2;
- if (*cp == '/') {
- cp++;
- continue;
- }
- if (strncmp(cp, "/../"+1, 3) == 0) {
- cp += 3;
- continue;
- }
- cp2 = strstr(cp, "/../");
- if (!cp2)
- break;
- cp = cp2 + 4;
- }
- if (cp != str) {
- static smallint warned = 0;
- if (!warned) {
- warned = 1;
- bb_error_msg("removing leading '%.*s' from member names",
- (int)(cp - str), str);
- }
- }
- return cp;
-}
-
/* NB: _DESTROYS_ str[len] character! */
static unsigned long long getOctal(char *str, int len)
{
diff --git a/archival/libarchive/unsafe_prefix.c b/archival/libarchive/unsafe_prefix.c
new file mode 100644
index 0000000..826c673
--- /dev/null
+++ b/archival/libarchive/unsafe_prefix.c
@@ -0,0 +1,36 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
+ */
+
+#include "libbb.h"
+#include "bb_archive.h"
+
+const char* FAST_FUNC strip_unsafe_prefix(const char *str)
+{
+ const char *cp = str;
+ while (1) {
+ char *cp2;
+ if (*cp == '/') {
+ cp++;
+ continue;
+ }
+ if (strncmp(cp, "/../"+1, 3) == 0) {
+ cp += 3;
+ continue;
+ }
+ cp2 = strstr(cp, "/../");
+ if (!cp2)
+ break;
+ cp = cp2 + 4;
+ }
+ if (cp != str) {
+ static smallint warned = 0;
+ if (!warned) {
+ warned = 1;
+ bb_error_msg("removing leading '%.*s' from member names",
+ (int)(cp - str), str);
+ }
+ }
+ return cp;
+}
diff --git a/archival/unzip.c b/archival/unzip.c
index 38a07e2..eed2256 100644
--- a/archival/unzip.c
+++ b/archival/unzip.c
@@ -596,14 +596,18 @@ int unzip_main(int argc, char **argv)
/* Skip extra header bytes */
unzip_skip(zip_header.formatted.extra_len);
+ /* Guard against "/abspath", "/../" and similar attacks */
+ overlapping_strcpy(dst_fn, strip_unsafe_prefix(dst_fn));
+
/* Filter zip entries */
if (find_list_entry(zreject, dst_fn)
|| (zaccept && !find_list_entry(zaccept, dst_fn))
) { /* Skip entry */
i = 'n';
- } else { /* Extract entry */
- if (listing) { /* List entry */
+ } else {
+ if (listing) {
+ /* List entry */
unsigned dostime = zip_header.formatted.modtime | (zip_header.formatted.moddate << 16);
if (!verbose) {
// " Length Date Time Name\n"
@@ -639,9 +643,11 @@ int unzip_main(int argc, char **argv)
total_size += zip_header.formatted.cmpsize;
}
i = 'n';
- } else if (dst_fd == STDOUT_FILENO) { /* Extracting to STDOUT */
+ } else if (dst_fd == STDOUT_FILENO) {
+ /* Extracting to STDOUT */
i = -1;
- } else if (last_char_is(dst_fn, '/')) { /* Extract directory */
+ } else if (last_char_is(dst_fn, '/')) {
+ /* Extract directory */
if (stat(dst_fn, &stat_buf) == -1) {
if (errno != ENOENT) {
bb_perror_msg_and_die("can't stat '%s'", dst_fn);
@@ -655,22 +661,27 @@ int unzip_main(int argc, char **argv)
}
} else {
if (!S_ISDIR(stat_buf.st_mode)) {
- bb_error_msg_and_die("'%s' exists but is not directory", dst_fn);
+ bb_error_msg_and_die("'%s' exists but is not a %s",
+ dst_fn, "directory");
}
}
i = 'n';
- } else { /* Extract file */
+ } else {
+ /* Extract file */
check_file:
- if (stat(dst_fn, &stat_buf) == -1) { /* File does not exist */
+ if (stat(dst_fn, &stat_buf) == -1) {
+ /* File does not exist */
if (errno != ENOENT) {
bb_perror_msg_and_die("can't stat '%s'", dst_fn);
}
i = 'y';
- } else { /* File already exists */
+ } else {
+ /* File already exists */
if (overwrite == O_NEVER) {
i = 'n';
- } else if (S_ISREG(stat_buf.st_mode)) { /* File is regular file */
+ } else if (S_ISREG(stat_buf.st_mode)) {
+ /* File is regular file */
if (overwrite == O_ALWAYS) {
i = 'y';
} else {
@@ -678,8 +689,10 @@ int unzip_main(int argc, char **argv)
my_fgets80(key_buf);
i = key_buf[0];
}
- } else { /* File is not regular file */
- bb_error_msg_and_die("'%s' exists but is not regular file", dst_fn);
+ } else {
+ /* File is not regular file */
+ bb_error_msg_and_die("'%s' exists but is not a %s",
+ dst_fn, "regular file");
}
}
}
More information about the busybox-cvs
mailing list