tar,unzip: postpone creation of symlinks with "suspicious" targets
This mostly reverts commit bc9bbeb2b8
"libarchive: do not extract unsafe symlinks unless $EXTRACT_UNSAFE_SYMLINKS=1"
Users report that it is somewhat too restrictive. See
https://bugs.busybox.net/show_bug.cgi?id=8411
In particular, this interferes with unpacking of busybox-based
filesystems with links like "sbin/applet" -> "../bin/busybox".
The change is made smaller by deleting ARCHIVE_EXTRACT_QUIET flag -
it is unused since 2010, and removing conditionals on it
allows commonalizing some error message codes.
function old new delta
create_or_remember_symlink - 94 +94
create_symlinks_from_list - 64 +64
tar_main 1002 1006 +4
unzip_main 2732 2724 -8
data_extract_all 984 891 -93
unsafe_symlink_target 147 - -147
------------------------------------------------------------------------------
(add/remove: 2/1 grow/shrink: 1/2 up/down: 162/-248) Total: -86 bytes
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko
parent
95121d98e6
commit
a84db18fc7
@ -107,9 +107,7 @@ void FAST_FUNC data_extract_all(archive_handle_t *archive_handle)
|
||||
}
|
||||
}
|
||||
else if (existing_sb.st_mtime >= file_header->mtime) {
|
||||
if (!(archive_handle->ah_flags & ARCHIVE_EXTRACT_QUIET)
|
||||
&& !S_ISDIR(file_header->mode)
|
||||
) {
|
||||
if (!S_ISDIR(file_header->mode)) {
|
||||
bb_error_msg("%s not created: newer or "
|
||||
"same age file exists", dst_name);
|
||||
}
|
||||
@ -125,7 +123,7 @@ void FAST_FUNC data_extract_all(archive_handle_t *archive_handle)
|
||||
/* Handle hard links separately */
|
||||
if (hard_link) {
|
||||
res = link(hard_link, dst_name);
|
||||
if (res != 0 && !(archive_handle->ah_flags & ARCHIVE_EXTRACT_QUIET)) {
|
||||
if (res != 0) {
|
||||
/* shared message */
|
||||
bb_perror_msg("can't create %slink '%s' to '%s'",
|
||||
"hard", dst_name, hard_link
|
||||
@ -165,10 +163,9 @@ void FAST_FUNC data_extract_all(archive_handle_t *archive_handle)
|
||||
}
|
||||
case S_IFDIR:
|
||||
res = mkdir(dst_name, file_header->mode);
|
||||
if ((res == -1)
|
||||
if ((res != 0)
|
||||
&& (errno != EISDIR) /* btw, Linux doesn't return this */
|
||||
&& (errno != EEXIST)
|
||||
&& !(archive_handle->ah_flags & ARCHIVE_EXTRACT_QUIET)
|
||||
) {
|
||||
bb_perror_msg("can't make dir %s", dst_name);
|
||||
}
|
||||
@ -198,27 +195,16 @@ void FAST_FUNC data_extract_all(archive_handle_t *archive_handle)
|
||||
*
|
||||
* Untarring bug.tar would otherwise place evil.py in '/tmp'.
|
||||
*/
|
||||
if (!unsafe_symlink_target(file_header->link_target)) {
|
||||
res = symlink(file_header->link_target, dst_name);
|
||||
if (res != 0
|
||||
&& !(archive_handle->ah_flags & ARCHIVE_EXTRACT_QUIET)
|
||||
) {
|
||||
/* shared message */
|
||||
bb_perror_msg("can't create %slink '%s' to '%s'",
|
||||
"sym",
|
||||
dst_name, file_header->link_target
|
||||
);
|
||||
}
|
||||
}
|
||||
create_or_remember_symlink(&archive_handle->symlink_placeholders,
|
||||
file_header->link_target,
|
||||
dst_name);
|
||||
break;
|
||||
case S_IFSOCK:
|
||||
case S_IFBLK:
|
||||
case S_IFCHR:
|
||||
case S_IFIFO:
|
||||
res = mknod(dst_name, file_header->mode, file_header->device);
|
||||
if ((res == -1)
|
||||
&& !(archive_handle->ah_flags & ARCHIVE_EXTRACT_QUIET)
|
||||
) {
|
||||
if (res != 0) {
|
||||
bb_perror_msg("can't create node %s", dst_name);
|
||||
}
|
||||
break;
|
||||
|
||||
@ -5,44 +5,37 @@
|
||||
#include "libbb.h"
|
||||
#include "bb_archive.h"
|
||||
|
||||
int FAST_FUNC unsafe_symlink_target(const char *target)
|
||||
void FAST_FUNC create_or_remember_symlink(llist_t **symlink_placeholders,
|
||||
const char *target,
|
||||
const char *linkname)
|
||||
{
|
||||
const char *dot;
|
||||
|
||||
if (target[0] == '/') {
|
||||
const char *var;
|
||||
unsafe:
|
||||
var = getenv("EXTRACT_UNSAFE_SYMLINKS");
|
||||
if (var) {
|
||||
if (LONE_CHAR(var, '1'))
|
||||
return 0; /* pretend it's safe */
|
||||
return 1; /* "UNSAFE!" */
|
||||
}
|
||||
bb_error_msg("skipping unsafe symlink to '%s' in archive,"
|
||||
" set %s=1 to extract",
|
||||
target,
|
||||
"EXTRACT_UNSAFE_SYMLINKS"
|
||||
if (target[0] == '/' || strstr(target, "..")) {
|
||||
llist_add_to(symlink_placeholders,
|
||||
xasprintf("%s%c%s", linkname, '\0', target)
|
||||
);
|
||||
/* Prevent further messages */
|
||||
setenv("EXTRACT_UNSAFE_SYMLINKS", "0", 0);
|
||||
return 1; /* "UNSAFE!" */
|
||||
return;
|
||||
}
|
||||
if (symlink(target, linkname) != 0) {
|
||||
/* shared message */
|
||||
bb_perror_msg_and_die("can't create %slink '%s' to '%s'",
|
||||
"sym", linkname, target
|
||||
);
|
||||
}
|
||||
}
|
||||
|
||||
dot = target;
|
||||
for (;;) {
|
||||
dot = strchr(dot, '.');
|
||||
if (!dot)
|
||||
return 0; /* safe target */
|
||||
void FAST_FUNC create_symlinks_from_list(llist_t *list)
|
||||
{
|
||||
while (list) {
|
||||
char *target;
|
||||
|
||||
/* Is it a path component starting with ".."? */
|
||||
if ((dot[1] == '.')
|
||||
&& (dot == target || dot[-1] == '/')
|
||||
/* Is it exactly ".."? */
|
||||
&& (dot[2] == '/' || dot[2] == '\0')
|
||||
) {
|
||||
goto unsafe;
|
||||
target = list->data + strlen(list->data) + 1;
|
||||
if (symlink(target, list->data)) {
|
||||
/* shared message */
|
||||
bb_error_msg_and_die("can't create %slink '%s' to '%s'",
|
||||
"sym",
|
||||
list->data, target
|
||||
);
|
||||
}
|
||||
/* NB: it can even be trailing ".", should only add 1 */
|
||||
dot += 1;
|
||||
list = list->link;
|
||||
}
|
||||
}
|
||||
|
||||
@ -1244,6 +1244,8 @@ int tar_main(int argc UNUSED_PARAM, char **argv)
|
||||
while (get_header_tar(tar_handle) == EXIT_SUCCESS)
|
||||
bb_got_signal = EXIT_SUCCESS; /* saw at least one header, good */
|
||||
|
||||
create_symlinks_from_list(tar_handle->symlink_placeholders);
|
||||
|
||||
/* Check that every file that should have been extracted was */
|
||||
while (tar_handle->accept) {
|
||||
if (!find_list_entry(tar_handle->reject, tar_handle->accept->data)
|
||||
|
||||
@ -345,7 +345,9 @@ static void unzip_create_leading_dirs(const char *fn)
|
||||
}
|
||||
|
||||
#if ENABLE_FEATURE_UNZIP_CDF
|
||||
static void unzip_extract_symlink(zip_header_t *zip, const char *dst_fn)
|
||||
static void unzip_extract_symlink(llist_t **symlink_placeholders,
|
||||
zip_header_t *zip,
|
||||
const char *dst_fn)
|
||||
{
|
||||
char *target;
|
||||
|
||||
@ -370,15 +372,9 @@ static void unzip_extract_symlink(zip_header_t *zip, const char *dst_fn)
|
||||
target[xstate.mem_output_size] = '\0';
|
||||
#endif
|
||||
}
|
||||
if (!unsafe_symlink_target(target)) {
|
||||
//TODO: libbb candidate
|
||||
if (symlink(target, dst_fn)) {
|
||||
/* shared message */
|
||||
bb_perror_msg_and_die("can't create %slink '%s' to '%s'",
|
||||
"sym", dst_fn, target
|
||||
);
|
||||
}
|
||||
}
|
||||
create_or_remember_symlink(symlink_placeholders,
|
||||
target,
|
||||
dst_fn);
|
||||
free(target);
|
||||
}
|
||||
#endif
|
||||
@ -490,6 +486,9 @@ int unzip_main(int argc, char **argv)
|
||||
llist_t *zaccept = NULL;
|
||||
llist_t *zreject = NULL;
|
||||
char *base_dir = NULL;
|
||||
#if ENABLE_FEATURE_UNZIP_CDF
|
||||
llist_t *symlink_placeholders = NULL;
|
||||
#endif
|
||||
int i;
|
||||
char key_buf[80]; /* must match size used by my_fgets80 */
|
||||
|
||||
@ -954,7 +953,7 @@ int unzip_main(int argc, char **argv)
|
||||
#if ENABLE_FEATURE_UNZIP_CDF
|
||||
if (S_ISLNK(file_mode)) {
|
||||
if (dst_fd != STDOUT_FILENO) /* not -p? */
|
||||
unzip_extract_symlink(&zip, dst_fn);
|
||||
unzip_extract_symlink(&symlink_placeholders, &zip, dst_fn);
|
||||
} else
|
||||
#endif
|
||||
{
|
||||
@ -990,6 +989,10 @@ int unzip_main(int argc, char **argv)
|
||||
total_entries++;
|
||||
}
|
||||
|
||||
#if ENABLE_FEATURE_UNZIP_CDF
|
||||
create_symlinks_from_list(symlink_placeholders);
|
||||
#endif
|
||||
|
||||
if ((opts & OPT_l) && quiet <= 1) {
|
||||
if (!verbose) {
|
||||
// " Length Date Time Name\n"
|
||||
|
||||
@ -64,6 +64,9 @@ typedef struct archive_handle_t {
|
||||
/* Currently processed file's header */
|
||||
file_header_t *file_header;
|
||||
|
||||
/* List of symlink placeholders */
|
||||
llist_t *symlink_placeholders;
|
||||
|
||||
/* Process the header component, e.g. tar -t */
|
||||
void FAST_FUNC (*action_header)(const file_header_t *);
|
||||
|
||||
@ -119,15 +122,14 @@ typedef struct archive_handle_t {
|
||||
#define ARCHIVE_RESTORE_DATE (1 << 0)
|
||||
#define ARCHIVE_CREATE_LEADING_DIRS (1 << 1)
|
||||
#define ARCHIVE_UNLINK_OLD (1 << 2)
|
||||
#define ARCHIVE_EXTRACT_QUIET (1 << 3)
|
||||
#define ARCHIVE_EXTRACT_NEWER (1 << 4)
|
||||
#define ARCHIVE_DONT_RESTORE_OWNER (1 << 5)
|
||||
#define ARCHIVE_DONT_RESTORE_PERM (1 << 6)
|
||||
#define ARCHIVE_NUMERIC_OWNER (1 << 7)
|
||||
#define ARCHIVE_O_TRUNC (1 << 8)
|
||||
#define ARCHIVE_REMEMBER_NAMES (1 << 9)
|
||||
#define ARCHIVE_EXTRACT_NEWER (1 << 3)
|
||||
#define ARCHIVE_DONT_RESTORE_OWNER (1 << 4)
|
||||
#define ARCHIVE_DONT_RESTORE_PERM (1 << 5)
|
||||
#define ARCHIVE_NUMERIC_OWNER (1 << 6)
|
||||
#define ARCHIVE_O_TRUNC (1 << 7)
|
||||
#define ARCHIVE_REMEMBER_NAMES (1 << 8)
|
||||
#if ENABLE_RPM
|
||||
#define ARCHIVE_REPLACE_VIA_RENAME (1 << 10)
|
||||
#define ARCHIVE_REPLACE_VIA_RENAME (1 << 9)
|
||||
#endif
|
||||
|
||||
|
||||
@ -197,7 +199,10 @@ void seek_by_jump(int fd, off_t amount) FAST_FUNC;
|
||||
void seek_by_read(int fd, off_t amount) FAST_FUNC;
|
||||
|
||||
const char *strip_unsafe_prefix(const char *str) FAST_FUNC;
|
||||
int unsafe_symlink_target(const char *target) FAST_FUNC;
|
||||
void create_or_remember_symlink(llist_t **symlink_placeholders,
|
||||
const char *target,
|
||||
const char *linkname) FAST_FUNC;
|
||||
void create_symlinks_from_list(llist_t *list) FAST_FUNC;
|
||||
|
||||
void data_align(archive_handle_t *archive_handle, unsigned boundary) FAST_FUNC;
|
||||
const llist_t *find_list_entry(const llist_t *list, const char *filename) FAST_FUNC;
|
||||
|
||||
@ -279,7 +279,7 @@ optional UUDECODE FEATURE_TAR_AUTODETECT FEATURE_SEAMLESS_BZ2
|
||||
testing "tar does not extract into symlinks" "\
|
||||
>>/tmp/passwd && uudecode -o input && tar xf input 2>&1 && rm passwd; cat /tmp/passwd; echo \$?
|
||||
" "\
|
||||
tar: skipping unsafe symlink to '/tmp/passwd' in archive, set EXTRACT_UNSAFE_SYMLINKS=1 to extract
|
||||
tar: can't create symlink 'passwd' to '/tmp/passwd'
|
||||
0
|
||||
" \
|
||||
"" "\
|
||||
@ -299,7 +299,7 @@ optional UUDECODE FEATURE_TAR_AUTODETECT FEATURE_SEAMLESS_BZ2
|
||||
testing "tar -k does not extract into symlinks" "\
|
||||
>>/tmp/passwd && uudecode -o input && tar xf input -k 2>&1 && rm passwd; cat /tmp/passwd; echo \$?
|
||||
" "\
|
||||
tar: skipping unsafe symlink to '/tmp/passwd' in archive, set EXTRACT_UNSAFE_SYMLINKS=1 to extract
|
||||
tar: can't create symlink 'passwd' to '/tmp/passwd'
|
||||
0
|
||||
" \
|
||||
"" "\
|
||||
@ -324,11 +324,11 @@ rm -rf etc usr
|
||||
' "\
|
||||
etc/ssl/certs/3b2716e5.0
|
||||
etc/ssl/certs/EBG_Elektronik_Sertifika_Hizmet_Sağlayıcısı.pem
|
||||
tar: skipping unsafe symlink to '/usr/share/ca-certificates/mozilla/EBG_Elektronik_Sertifika_Hizmet_Sağlayıcısı.crt' in archive, set EXTRACT_UNSAFE_SYMLINKS=1 to extract
|
||||
etc/ssl/certs/f80cc7f6.0
|
||||
usr/share/ca-certificates/mozilla/EBG_Elektronik_Sertifika_Hizmet_Sağlayıcısı.crt
|
||||
0
|
||||
etc/ssl/certs/3b2716e5.0 -> EBG_Elektronik_Sertifika_Hizmet_Sağlayıcısı.pem
|
||||
etc/ssl/certs/EBG_Elektronik_Sertifika_Hizmet_Sağlayıcısı.pem -> /usr/share/ca-certificates/mozilla/EBG_Elektronik_Sertifika_Hizmet_Sağlayıcısı.crt
|
||||
etc/ssl/certs/f80cc7f6.0 -> EBG_Elektronik_Sertifika_Hizmet_Sağlayıcısı.pem
|
||||
" \
|
||||
"" ""
|
||||
@ -346,9 +346,9 @@ ls symlink/bb_test_evilfile
|
||||
' "\
|
||||
anything.txt
|
||||
symlink
|
||||
tar: skipping unsafe symlink to '/tmp' in archive, set EXTRACT_UNSAFE_SYMLINKS=1 to extract
|
||||
symlink/bb_test_evilfile
|
||||
0
|
||||
tar: can't create symlink 'symlink' to '/tmp'
|
||||
1
|
||||
ls: /tmp/bb_test_evilfile: No such file or directory
|
||||
ls: bb_test_evilfile: No such file or directory
|
||||
symlink/bb_test_evilfile
|
||||
|
||||
Loading…
Reference in New Issue
Block a user