rsync - Sep 2009 - DO NOT REPLY [Bug 6701] New: permission of attributes are not preserved

https://bugzilla.samba.org/show_bug.cgi?id=6701

           Summary: permission of attributes are not preserved
           Product: rsync
           Version: 3.1.0
          Platform: Other
        OS/Version: Solaris
            Status: NEW
          Severity: minor
          Priority: P3
         Component: core
        AssignedTo: wayned at samba.org
        ReportedBy: cavalli at cilea.it
         QAContact: rsync-qa at samba.org


This relates to fake-super on solaris, but actually is more general because
xattr are files so have ownership and permission which is not preserved by  -X
(-XX)

Suppose I have this situation

root at opensolaris:~/src/rsync# runat /data/cavalli/test ls -l
total 2
-rw-rw---- 1 cavalli other  13 2009-09-08 08:14 rsync.%stat
-r--r--r-- 1 root    root   84 2009-09-08 08:14 SUNWattr_ro
-rw-r--r-- 1 root    root  408 2009-09-08 08:14 SUNWattr_rw

Then root does a rsync -XX. We end up with

-rw-rw---- 1 root root  13 2009-09-08 08:14 rsync.%stat

So that user cavalli does no longer see fake-super information in the
"backup
of the backup"...

In this case a quick solution could be creating the xattr with read permission
for "other", but the problem is more general.

I think that -X beavhiour should be:

- for every user preserve permissions 
- for root preserve permission and ownerships

diff --git a/lib/sysxattrs.c b/lib/sysxattrs.c
index d55ee0c..c9a38cd 100644
--- a/lib/sysxattrs.c
+++ b/lib/sysxattrs.c
@@ -191,7 +191,7 @@ int sys_lsetxattr(const char *path, const char *name, const 
 {
        int attrfd;
        size_t bufpos;
-       mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP;
+       mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH;

        if ((attrfd = attropen(path, name, O_CREAT|O_TRUNC|O_WRONLY, mode)) <
0)
                return -1;


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------- Comment #1 from matt at mattmccutchen.net  2009-09-10 15:29 CST -------
Is the mode and ownership all, or is there other metadata to worry about?  Do
xattrs have mtimes?  Does a file have a separate set of directory-like
permissions that control the creation, deletion, and renaming of its xattrs? 
Can xattrs have ACLs?  Can they have their own xattrs?  :D

This is going to be fun to implement.


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------- Comment #2 from matt at mattmccutchen.net  2009-09-10 15:51 CST -------
(In reply to comment #1)
> Is the mode and ownership all, or is there other metadata to worry about? 
Do
> xattrs have mtimes?  Does a file have a separate set of directory-like
> permissions that control the creation, deletion, and renaming of its
xattrs?
> Can xattrs have ACLs?  Can they have their own xattrs?  :D
I thought I was joking, but the answer to all questions is yes!  (At least in
the interface, though not on current filesystems.)

http://docs.sun.com/app/docs/doc/816-5175/fsattr-5?a=view

If rsync is going to go out on a limb and support this, maybe the best approach
would be to hang an entire file list off each file that has xattrs.


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--- Comment #3 from Matt McCutchen <matt at mattmccutchen.net> 2011-06-07
23:54:03 UTC ---
In the absence of a protocol extension to carry the actual attributes, one
reasonable thing rsync could do is set the permissions and ownership to emulate
the Linux access control rules for user xattrs, i.e., same as the file itself
except never executable.  (Rsync takes the view that the entire Solaris xattr
space corresponds to the Linux user namespace; the analogy is imperfect but
better than the alternatives.)

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