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unzip: prevent attacks via malicious filenames 

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2015-02-10 01:30:43 +01:00
parent 23cfaab47d
commit 8c06bc6ba1
4 changed files with 63 additions and 43 deletions
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5
archival/libarchive/Kbuild.src
View File

@ -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

30
archival/libarchive/get_header_tar.c
View File

@ -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)
{

36
archival/libarchive/unsafe_prefix.c Normal file
View File

@ -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;
}

35
archival/unzip.c
View File

@ -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");
}
}
}