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'\" t
.\" Title: idmap_script
.\" Author: [see the "AUTHOR" section]
.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
.\" Date: 05/09/2024
.\" Manual: System Administration tools
.\" Source: Samba 4.20.1
.\" Language: English
.\"
.TH "IDMAP_SCRIPT" "8" "05/09/2024" "Samba 4\&.20\&.1" "System Administration tools"
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.el .ds Aq '
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.nh
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.ad l
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.\" * MAIN CONTENT STARTS HERE *
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.SH "NAME"
idmap_script \- Samba\*(Aqs idmap_script Backend for Winbind
.SH "DESCRIPTION"
.PP
The idmap_script plugin is a substitute for the idmap_tdb2 backend used by winbindd for storing SID/uid/gid mapping tables in clustered environments with Samba and CTDB\&. It is a read only backend that uses a script to perform mapping\&.
.PP
It was developed out of the idmap_tdb2 back end and does not store SID/uid/gid mappings in a TDB, since the winbind_cache tdb will store the mappings once they are provided\&.
.SH "IDMAP OPTIONS"
.PP
range = low \- high
.RS 4
Defines the available matching uid and gid range for which the backend is authoritative\&.
.RE
.PP
script
.RS 4
This option can be used to configure an external program for performing id mappings\&.
.RE
.SH "IDMAP SCRIPT"
.PP
The script idmap backend supports an external program for performing id mappings through the
/etc/samba/smb\&.conf
option
\fIidmap config * : script\fR
or its deprecated legacy form
\fIidmap : script\fR\&.
.PP
The script should accept the following command line options\&.
.sp
.if n \{\
.RS 4
.\}
.nf
SIDTOID S\-1\-xxxx
IDTOSID UID xxxx
IDTOSID GID xxxx
IDTOSID XID xxxx
.fi
.if n \{\
.RE
.\}
.PP
And it should return one of the following responses as a single line of text\&.
.sp
.if n \{\
.RS 4
.\}
.nf
UID:yyyy
GID:yyyy
XID:yyyy
SID:ssss
ERR:yyyy
.fi
.if n \{\
.RE
.\}
.PP
XID indicates that the ID returned should be both a UID and a GID\&. That is, it requests an ID_TYPE_BOTH, but it is ultimately up to the script whether or not it can honor that request\&. It can choose to return a UID or a GID mapping only\&.
.SH "EXAMPLES"
.PP
This example shows how script is used as the default idmap backend using an external program via the script parameter:
.sp
.if n \{\
.RS 4
.\}
.nf
[global]
idmap config * : backend = script
idmap config * : range = 1000000\-2000000
idmap config * : script = /usr/local/samba/bin/idmap_script\&.sh
.fi
.if n \{\
.RE
.\}
.PP
This shows a simple script to partially perform the task:
.sp
.if n \{\
.RS 4
.\}
.nf
#!/bin/sh
#
# Uncomment this if you want some logging
#echo $@ >> /tmp/idmap\&.sh\&.log
if [ "$1" == "SIDTOID" ]
then
# Note\&. The number returned has to be within the range defined
#echo "Sending UID:1000005" >> /tmp/idmap\&.sh\&.log
echo "UID:1000005"
exit 0
else
#echo "Sending ERR: No idea what to do" >> /tmp/idmap\&.sh\&.log
echo "ERR: No idea what to do"
exit 1
fi
.fi
.if n \{\
.RE
.\}
.PP
Clearly, this script is not enough, as it should probably use wbinfo to determine if an incoming SID is a user or group SID and then look up the mapping in a table or use some other mechanism for mapping SIDs to UIDs and etc\&.
.PP
Please be aware that the script is called with the _NO_WINBINDD environment variable set to 1\&. This prevents recursive calls into winbind from the script both via explicit calls to wbinfo and via implicit calls via nss_winbind\&. For example a call to
ls \-l
could trigger such an infinite recursion\&.
.PP
It is safe to call
wbinfo \-n
and
wbinfo \-s
from within an idmap script\&. To do so, the script must unset the _NO_WINBINDD environment variable right before the call to
wbinfo
and set it to 1 again right after
wbinfo
has returned to protect against the recursion\&.
.SH "AUTHOR"
.PP
The original Samba software and related utilities were created by Andrew Tridgell\&. Samba is now developed by the Samba Team as an Open Source project similar to the way the Linux kernel is developed\&.
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