unzip: prevent attacks via malicious filenames
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
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23cfaab47d
commit
8c06bc6ba1
@ -30,6 +30,7 @@ COMMON_FILES:= \
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DPKG_FILES:= \
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unpack_ar_archive.o \
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filter_accept_list_reassign.o \
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unsafe_prefix.o \
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get_header_ar.o \
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get_header_tar.o \
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get_header_tar_gz.o \
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@ -44,7 +45,7 @@ lib-$(CONFIG_DPKG_DEB) += $(DPKG_FILES)
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lib-$(CONFIG_AR) += get_header_ar.o unpack_ar_archive.o
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lib-$(CONFIG_CPIO) += get_header_cpio.o
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lib-$(CONFIG_TAR) += get_header_tar.o
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lib-$(CONFIG_TAR) += get_header_tar.o unsafe_prefix.o
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lib-$(CONFIG_FEATURE_TAR_TO_COMMAND) += data_extract_to_command.o
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lib-$(CONFIG_LZOP) += lzo1x_1.o lzo1x_1o.o lzo1x_d.o
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lib-$(CONFIG_LZOP_COMPR_HIGH) += lzo1x_9x.o
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@ -53,7 +54,7 @@ lib-$(CONFIG_UNLZMA) += open_transformer.o decompress_unlzma.
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lib-$(CONFIG_UNXZ) += open_transformer.o decompress_unxz.o
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lib-$(CONFIG_GUNZIP) += open_transformer.o decompress_gunzip.o
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lib-$(CONFIG_UNCOMPRESS) += open_transformer.o decompress_uncompress.o
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lib-$(CONFIG_UNZIP) += open_transformer.o decompress_gunzip.o
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lib-$(CONFIG_UNZIP) += open_transformer.o decompress_gunzip.o unsafe_prefix.o
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lib-$(CONFIG_RPM2CPIO) += open_transformer.o decompress_gunzip.o get_header_cpio.o
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lib-$(CONFIG_RPM) += open_transformer.o decompress_gunzip.o get_header_cpio.o
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@ -17,36 +17,6 @@
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typedef uint32_t aliased_uint32_t FIX_ALIASING;
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typedef off_t aliased_off_t FIX_ALIASING;
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const char* FAST_FUNC strip_unsafe_prefix(const char *str)
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{
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const char *cp = str;
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while (1) {
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char *cp2;
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if (*cp == '/') {
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cp++;
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continue;
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}
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if (strncmp(cp, "/../"+1, 3) == 0) {
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cp += 3;
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continue;
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}
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cp2 = strstr(cp, "/../");
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if (!cp2)
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break;
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cp = cp2 + 4;
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}
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if (cp != str) {
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static smallint warned = 0;
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if (!warned) {
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warned = 1;
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bb_error_msg("removing leading '%.*s' from member names",
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(int)(cp - str), str);
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}
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}
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return cp;
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}
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/* NB: _DESTROYS_ str[len] character! */
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static unsigned long long getOctal(char *str, int len)
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{
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36
archival/libarchive/unsafe_prefix.c
Normal file
36
archival/libarchive/unsafe_prefix.c
Normal file
@ -0,0 +1,36 @@
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/* vi: set sw=4 ts=4: */
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/*
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* Licensed under GPLv2 or later, see file LICENSE in this source tree.
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*/
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#include "libbb.h"
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#include "bb_archive.h"
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const char* FAST_FUNC strip_unsafe_prefix(const char *str)
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{
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const char *cp = str;
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while (1) {
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char *cp2;
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if (*cp == '/') {
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cp++;
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continue;
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}
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if (strncmp(cp, "/../"+1, 3) == 0) {
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cp += 3;
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continue;
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}
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cp2 = strstr(cp, "/../");
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if (!cp2)
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break;
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cp = cp2 + 4;
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}
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if (cp != str) {
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static smallint warned = 0;
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if (!warned) {
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warned = 1;
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bb_error_msg("removing leading '%.*s' from member names",
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(int)(cp - str), str);
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}
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}
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return cp;
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}
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@ -596,14 +596,18 @@ int unzip_main(int argc, char **argv)
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/* Skip extra header bytes */
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unzip_skip(zip_header.formatted.extra_len);
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/* Guard against "/abspath", "/../" and similar attacks */
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overlapping_strcpy(dst_fn, strip_unsafe_prefix(dst_fn));
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/* Filter zip entries */
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if (find_list_entry(zreject, dst_fn)
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|| (zaccept && !find_list_entry(zaccept, dst_fn))
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) { /* Skip entry */
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i = 'n';
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} else { /* Extract entry */
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if (listing) { /* List entry */
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} else {
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if (listing) {
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/* List entry */
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unsigned dostime = zip_header.formatted.modtime | (zip_header.formatted.moddate << 16);
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if (!verbose) {
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// " Length Date Time Name\n"
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@ -639,9 +643,11 @@ int unzip_main(int argc, char **argv)
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total_size += zip_header.formatted.cmpsize;
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}
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i = 'n';
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} else if (dst_fd == STDOUT_FILENO) { /* Extracting to STDOUT */
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} else if (dst_fd == STDOUT_FILENO) {
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/* Extracting to STDOUT */
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i = -1;
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} else if (last_char_is(dst_fn, '/')) { /* Extract directory */
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} else if (last_char_is(dst_fn, '/')) {
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/* Extract directory */
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if (stat(dst_fn, &stat_buf) == -1) {
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if (errno != ENOENT) {
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bb_perror_msg_and_die("can't stat '%s'", dst_fn);
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@ -655,22 +661,27 @@ int unzip_main(int argc, char **argv)
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}
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} else {
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if (!S_ISDIR(stat_buf.st_mode)) {
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bb_error_msg_and_die("'%s' exists but is not directory", dst_fn);
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bb_error_msg_and_die("'%s' exists but is not a %s",
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dst_fn, "directory");
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}
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}
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i = 'n';
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} else { /* Extract file */
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} else {
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/* Extract file */
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check_file:
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if (stat(dst_fn, &stat_buf) == -1) { /* File does not exist */
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if (stat(dst_fn, &stat_buf) == -1) {
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/* File does not exist */
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if (errno != ENOENT) {
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bb_perror_msg_and_die("can't stat '%s'", dst_fn);
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}
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i = 'y';
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} else { /* File already exists */
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} else {
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/* File already exists */
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if (overwrite == O_NEVER) {
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i = 'n';
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} else if (S_ISREG(stat_buf.st_mode)) { /* File is regular file */
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} else if (S_ISREG(stat_buf.st_mode)) {
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/* File is regular file */
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if (overwrite == O_ALWAYS) {
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i = 'y';
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} else {
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@ -678,8 +689,10 @@ int unzip_main(int argc, char **argv)
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my_fgets80(key_buf);
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i = key_buf[0];
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}
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} else { /* File is not regular file */
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bb_error_msg_and_die("'%s' exists but is not regular file", dst_fn);
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} else {
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/* File is not regular file */
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bb_error_msg_and_die("'%s' exists but is not a %s",
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dst_fn, "regular file");
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}
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}
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}
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