[PATCH] rsync without --perms may set bogus permissions

[Christian Franke <Christian dot Franke at t-online dot de>]

Rsync may set bogus permissions if --perms is not specified and ACLs are 
enabled. This happens if the destination directory was not created by 
Cygwin itself. Testcase:


$ cygcheck -f /bin/cygwin1.dll
cygwin-1.7.7-1

$ cygcheck -f /bin/rsync.exe
rsync-3.0.7-1

$ umask
0022

$ cmd /c 'mkdir C:\test'

$ cd /cygdrive/c/test

$ echo test >source

$ rsync -vvv source dest
...
got ACL-based default perms 5070 for directory . <<---rwx---
...

$ ls -l
-rw-r--r--+ 1 someone none 5 2010-11-25 19:50 source
----r-----+ 1 someone none 5 2010-11-25 19:50 dest

$ cat dest
cat: dest: Permission denied


For some (security?) reason rsync (without --perms) does not rely on 
permissions set by open(., O_CREAT, .). The permissions are set later 
based on the default ACL of the parent dir.

The problem is that the rsync function acls.c:rsync_acl_get_perms() 
expects that the default ACL has an "other" entry and that the "mask" 
entry has only 3 rwx-bits.

The default ACL returned by Cygwin does not contain an "other" entry in 
this case. The default "mask" is 0777 (OK or Cygwin bug?):

$ getfacl .
# file: .
# owner: someone
# group: none
user::rwx
group::---
group:root:rwx
group:SYSTEM:rwx
group:users:rwx
mask:rwx
other:---
default:user::rwx
default:group:root:rwx
default:group:SYSTEM:rwx
default:group:users:rwx
#default:other:... <<--- missing, expected by rsync
default:mask:rwx <<--- Cygwin returns 0777, rsync expects <= 07

With the above default ACL the function rsync_acl_get_perms() returns:
  (07 << 6) + ((uchar)0777 << 3) + 0200/*NO_ENTRY*/ = 05070
This is interpreted as ---rwx--- which results in a file not readable by 
the user.

The attached patch should fix this.

--
Christian Franke

--- rsync-3.0.7.orig/acls.c	2009-04-11 01:09:39.000000000 +0200
+++ rsync-3.0.7/acls.c	2010-11-25 15:37:45.859375000 +0100
@@ -122,12 +122,13 @@
 }
 
 /* Extracts and returns the permission bits from the ACL.  This cannot be
- * called on an rsync_acl that has NO_ENTRY in any spot but the mask. */
+ * called on an rsync_acl that has NO_ENTRY in user_obj. */
 static int rsync_acl_get_perms(const rsync_acl *racl)
 {
 	return (racl->user_obj << 6)
-	     + ((racl->mask_obj != NO_ENTRY ? racl->mask_obj : racl->group_obj) << 3)
-	     + racl->other_obj;
+	     | (((racl->mask_obj != NO_ENTRY ? racl->mask_obj
+	          : racl->group_obj != NO_ENTRY ? racl->group_obj : 0) & 7) << 3)
+	     | ((racl->other_obj != NO_ENTRY ? racl->other_obj : 0) & 7);
 }
 
 /* Removes the permission-bit entries from the ACL because these

--
Problem reports:       http://cygwin.com/problems.html
FAQ:                   http://cygwin.com/faq/
Documentation:         http://cygwin.com/docs.html
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple