rsync - Nov 2006 - DO NOT REPLY [Bug 4263] New: Symlinks gets corruped when rsyncd is used to 'put' the symlink.

https://bugzilla.samba.org/show_bug.cgi?id=4263

           Summary: Symlinks gets corruped when rsyncd is used to 'put'
the
                    symlink.
           Product: rsync
           Version: 2.6.8
          Platform: Sparc
        OS/Version: Solaris
            Status: NEW
          Severity: critical
          Priority: P3
         Component: core
        AssignedTo: wayned@samba.org
        ReportedBy: bjorn.unden@se.atlascopco.com
         QAContact: rsync-qa@samba.org


I get problem with symbolic links when I do a backup between two servers using
rsyncd on one of them.
When I get the backup everything works fine. See the GET-part belowe.
But when I shall put it back to the original place in the first server, rsync
strips off the initial '/' in the symlink and this will not work. See
the
PUT-part belowe.
I have tryed it out a lot and it seems to work fine to 'GET' but not to
'PUT'
when I use rsyncd.

GET
===toos6<kalle> ls -al
total 6
drwxrwxr-x   2 root     other        512 Nov 27 19:15 .
drwxrwxr-x  11 root     other        512 Oct 25 14:40 ..
lrwxrwxrwx   1 root     other         47 Nov 27 19:15 LDAPBrowser ->
/opt/ptc/Aphelion/SyntegraLDAPBrowser/ptclbe.sh

toos22<bin> rsync -av toos6::ptc/kalle/LDAPBrowser
/backup/pdmlink_061126/Aphelion_latest/bin
receiving file list ... done
LDAPBrowser -> /opt/ptc/Aphelion/SyntegraLDAPBrowser/ptclbe.sh

sent 91 bytes  received 149 bytes  160.00 bytes/sec
total size is 47  speedup is 0.20
toos22<bin> ls -al
total 6
drwxrwxr-x   2 root     other        512 Nov 27 19:15 .
drwxrwxr-x  11 root     other        512 Oct 25 14:40 ..
lrwxrwxrwx   1 root     other         47 Nov 27 19:15 LDAPBrowser ->
/opt/ptc/Aphelion/SyntegraLDAPBrowser/ptclbe.sh

PUT
===toos22<bin> ls -al
total 6
drwxrwxr-x   2 root     other        512 Nov 27 19:15 .
drwxrwxr-x  11 root     other        512 Oct 25 14:40 ..
lrwxrwxrwx   1 root     other         47 Nov 26 23:00 LDAPBrowser ->
/opt/ptc/Aphelion/SyntegraLDAPBrowser/ptclbe.sh

toos22<bin> rsync -av
/backup/pdmlink_061126/Aphelion_latest/bin/LDAPBrowser
toos6::ptc/kalle
building file list ... done
LDAPBrowser -> /opt/ptc/Aphelion/SyntegraLDAPBrowser/ptclbe.sh

sent 109 bytes  received 22 bytes  262.00 bytes/sec
total size is 49  speedup is 0.37

toos6<kalle> ls -al
total 6
drwxrwxr-x   2 root     other        512 Nov 27 19:15 .
drwxrwxr-x  11 root     other        512 Oct 25 14:40 ..
lrwxrwxrwx   1 root     other         47 Nov 27 19:15 LDAPBrowser ->
opt/ptc/Aphelion/SyntegraLDAPBrowser/ptclbe.sh


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wayned@samba.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|critical                    |enhancement
             Status|NEW                         |ASSIGNED
            Summary|Symlinks gets corruped when |Change the daemon's symlink
                   |rsyncd is used to 'put' the |safety mode to allow
                   |symlink.                    |absolute symlinks
            Version|2.6.8                       |3.0.0




------- Comment #1 from wayned@samba.org  2006-11-28 10:08 MST -------
This is a safety feature when running the rsync daemon without chroot.  The
easiest way to work around it is to set "use chroot = yes" in the
config file.

I looked into improving the symlink safety mode to not modify an absolute
symlink, but this will require changing rsync to chdir() into every destination
directory when making changes (so that a user can't substitute a symlink for
a
directory in between a path's validity change and its use), so I deferred
this
change from 2.6.9 to a later release.  If 3.0.0 gets changed to use more
chdir() calls, I will revisit making a non-chroot daemon have a safe symlink
mode that doesn't mangle absolute symlinks.

Another, easier change would be to allow the config file to choose to accept
unsafe symlinks in a non-chroot area.  You can manually disable the code that
sanitizes the symlinks by looking for a sanitize_path() call inside an #ifdef
SUPPORT_LINKS section in flist.c -- if that call were commented out, the
symlinks would not be changed by a receiving daemon.


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------- Comment #2 from matt@mattmccutchen.net  2007-12-14 21:45 CST -------
If you use the "munge symlinks" feature recently added to the
development
rsync, you won't be able to follow the symlinks on the daemon but the daemon
will regurgitate them verbatim.


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wayned@samba.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED




------- Comment #3 from wayned@samba.org  2007-12-15 11:42 CST -------
As Matt points out, this is now possible.


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