tar: on extract, everything up to and including last ".." is stripped

function                                             old     new   delta
get_header_tar                                      1493    1545     +52

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 22 insertions, 5 deletions

diff --git a/archival/libarchive/get_header_tar.c b/archival/libarchive/get_header_tar.c
index 2e0332792..6a1532c86 100644
--- a/archival/libarchive/get_header_tar.c
+++ b/archival/libarchive/get_header_tar.c
@@ -422,11 +422,28 @@ char FAST_FUNC get_header_tar(archive_handle_t *archive_handle)
                 p_linkname = NULL;
         }
 #endif
-        if (strncmp(file_header->name, "/../"+1, 3) == 0
-         || strstr(file_header->name, "/../")
-        ) {
-                bb_error_msg_and_die("name with '..' encountered: '%s'",
-                                file_header->name);
+
+        /* Everything up to and including last ".." component is stripped */
+        cp = file_header->name;
+        while (1) {
+                char *cp2;
+                if (strncmp(cp, "/../"+1, 3) == 0) {
+                        cp += 3;
+                        continue;
+                }
+                cp2 = strstr(cp, "/../");
+                if (cp2) {
+                        cp = cp2 + 4;
+                        continue;
+                }
+                break;
+        }
+        if (cp != file_header->name) {
+                if (!(archive_handle->ah_flags & ARCHIVE_TAR__TRUNC_WARNED)) {
+                        archive_handle->ah_flags |= ARCHIVE_TAR__TRUNC_WARNED;
+                        bb_error_msg("removing leading '%.*s'", (int)(cp - file_header->name), file_header->name);
+                }
+                overlapping_strcpy(file_header->name, cp);
         }
 
         /* Strip trailing '/' in directories */