+++ /dev/null
-From a84db18fc71d09e801df0ebca048d82e90b32c6a Mon Sep 17 00:00:00 2001
-From: Denys Vlasenko <vda.linux@googlemail.com>
-Date: Tue, 20 Feb 2018 15:57:45 +0100
-Subject: [PATCH] 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>
----
- archival/libarchive/data_extract_all.c | 28 ++++----------
- archival/libarchive/unsafe_symlink_target.c | 59 +++++++++++++----------------
- archival/tar.c | 2 +
- archival/unzip.c | 25 ++++++------
- include/bb_archive.h | 23 ++++++-----
- testsuite/tar.tests | 10 ++---
- 6 files changed, 68 insertions(+), 79 deletions(-)
-
-diff --git a/archival/libarchive/data_extract_all.c b/archival/libarchive/data_extract_all.c
-index d3a6df5e8..8fa69ffaf 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 441ba8b24..8dcafeaa1 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 9ed3821d5..415ebde0d 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 da4b2a544..0d00d8dc9 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"
-diff --git a/include/bb_archive.h b/include/bb_archive.h
-index 8ed20d70e..a5c61e95b 100644
---- a/include/bb_archive.h
-+++ b/include/bb_archive.h
-@@ -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;
-diff --git a/testsuite/tar.tests b/testsuite/tar.tests
-index b7cd74ca5..1675b07b1 100755
---- a/testsuite/tar.tests
-+++ b/testsuite/tar.tests
-@@ -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
---
-2.16.2
-
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