Re: [Bug-tar] leading / included in incremental snapshot rename code

[Sergey Poznyakoff]

Nicholas Cole <address@hidden> ha escrit:

> This patch causes tar to strip leading / from rename codes during
> creation. Can you also patch tar to strip leading / from rename
> codes during extraction? This would prevent odd behaivor when
> extracting an archive created with an unpatched version of tar and
> prevent malicious use of rename codes

Yes, this is reasonable. Here is a patch.

Regards,
Sergey

Index: src/incremen.c
===================================================================
RCS file: /cvsroot/tar/tar/src/incremen.c,v
retrieving revision 1.58
diff -p -u -r1.58 incremen.c
--- src/incremen.c      29 Sep 2007 00:47:59 -0000      1.58
+++ src/incremen.c      1 Oct 2007 21:54:17 -0000
@@ -1410,6 +1410,19 @@ try_purge_directory (char const *directo
          arc += strlen (arc) + 1;
          dst = arc + 1;
 
+         /* Ensure that neither source nor destination are absolute file
+            names (unless permitted by -P option), and that they do not
+            contain dubious parts (e.g. ../).
+
+            This is an extra safety precaution. Besides, it might be
+            necessary to extract from archives created with tar versions
+            prior to 1.19. */
+         
+         if (*src)
+           src = safer_name_suffix (src, false, absolute_names_option);
+         if (*dst)
+           dst = safer_name_suffix (dst, false, absolute_names_option);
+         
          if (*src == 0)
            src = temp_stub;
          else if (*dst == 0)