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tar,unzip: postpone creation of symlinks with "suspicious" targets

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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
2018-02-20 15:57:45 +01:00
parent 95121d98e6
commit a84db18fc7
6 changed files with 71 additions and 82 deletions
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23
include/bb_archive.h
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@@ -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;