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authorDenys Vlasenko2018-02-20 15:57:45 +0100
committerDenys Vlasenko2018-02-20 16:06:53 +0100
commita84db18fc71d09e801df0ebca048d82e90b32c6a (patch)
tree1eda8cd659f78406f1b9f86d5e0b5757af20bad9 /archival
parent95121d98e6da12599246d8e25c3f300e422a06fb (diff)
downloadbusybox-a84db18fc71d09e801df0ebca048d82e90b32c6a.zip
busybox-a84db18fc71d09e801df0ebca048d82e90b32c6a.tar.gz
tar,unzip: postpone creation of symlinks with "suspicious" targets
This mostly reverts commit bc9bbeb2b81001e8731cd2ae501c8fccc8d87cc7 "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>
Diffstat (limited to 'archival')
-rw-r--r--archival/libarchive/data_extract_all.c28
-rw-r--r--archival/libarchive/unsafe_symlink_target.c59
-rw-r--r--archival/tar.c2
-rw-r--r--archival/unzip.c25
4 files changed, 49 insertions, 65 deletions
diff --git a/archival/libarchive/data_extract_all.c b/archival/libarchive/data_extract_all.c
index d3a6df5..8fa69ff 100644
--- a/archival/libarchive/data_extract_all.c
+++ b/archival/libarchive/data_extract_all.c
@@ -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;
diff --git a/archival/libarchive/unsafe_symlink_target.c b/archival/libarchive/unsafe_symlink_target.c
index 441ba8b..8dcafea 100644
--- a/archival/libarchive/unsafe_symlink_target.c
+++ b/archival/libarchive/unsafe_symlink_target.c
@@ -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)
+ );
+ return;
+ }
+ if (symlink(target, linkname) != 0) {
+ /* shared message */
+ bb_perror_msg_and_die("can't create %slink '%s' to '%s'",
+ "sym", linkname, target
);
- /* Prevent further messages */
- setenv("EXTRACT_UNSAFE_SYMLINKS", "0", 0);
- return 1; /* "UNSAFE!" */
}
+}
- 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;
}
}
diff --git a/archival/tar.c b/archival/tar.c
index 9ed3821..415ebde 100644
--- a/archival/tar.c
+++ b/archival/tar.c
@@ -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)
diff --git a/archival/unzip.c b/archival/unzip.c
index da4b2a5..0d00d8d 100644
--- a/archival/unzip.c
+++ b/archival/unzip.c
@@ -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"