1IDMAP_SCRIPT(8) System Administration tools IDMAP_SCRIPT(8)
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6 idmap_script - Samba's idmap_script Backend for Winbind
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9 The idmap_script plugin is a substitute for the idmap_tdb2 backend used
10 by winbindd for storing SID/uid/gid mapping tables in clustered
11 environments with Samba and CTDB. It is a read only backend that uses a
12 script to perform mapping.
13 It was developed out of the idmap_tdb2 back end and does not store
15 SID/uid/gid mappings in a TDB, since the winbind_cache tdb will store
16 the mappings once they are provided.
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19 range = low - high
20 Defines the available matching uid and gid range for which the
21 backend is authoritative.
22 script
24 This option can be used to configure an external program for
25 performing id mappings.
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28 The tdb2 idmap backend supports an external program for performing id
29 mappings through the /etc/samba/smb.conf option idmap config * : script
30 or its deprecated legacy form idmap : script.
31 The mappings obtained by the script are then stored in the idmap tdb2
33 database instead of mappings created by the incrementing id counters.
34 It is therefore important that the script covers the complete range of
35 SIDs that can be passed in for SID to Unix ID mapping, since otherwise
36 SIDs unmapped by the script might get mapped to IDs that had previously
37 been mapped by the script.
38 The script should accept the following command line options.
40 SIDTOID S-1-xxxx
42 IDTOSID UID xxxx
43 IDTOSID GID xxxx
44 IDTOSID XID xxxx
45 And it should return one of the following responses as a single line of
48 text.
49 UID:yyyy
51 GID:yyyy
52 XID:yyyy
53 SID:ssss
54 ERR:yyyy
55 XID indicates that the ID returned should be both a UID and a GID. That
58 is, it requests an ID_TYPE_BOTH, but it is ultimately up to the script
59 whether or not it can honor that request. It can choose to return a UID
60 or a GID mapping only.
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63 This example shows how script is used as a the default idmap backend
64 using an external program via the script parameter:
65 [global]
67 idmap config * : backend = script
68 idmap config * : range = 1000000-2000000
69 idmap config * : script = /usr/local/samba/bin/idmap_script.sh
70 This shows a simple script to partially perform the task:
73 #!/bin/sh
75 #
76 # Uncomment this if you want some logging
77 #echo $@ >> /tmp/idmap.sh.log
78 if [ "$1" == "SIDTOID" ]
79 then
80 # Note. The number returned has to be within the range defined
81 #echo "Sending UID:1000005" >> /tmp/idmap.sh.log
82 echo "UID:1000005"
83 exit 0
84 else
85 #echo "Sending ERR: No idea what to do" >> /tmp/idmap.sh.log
86 echo "ERR: No idea what to do"
87 exit 1
88 fi
89 Clearly, this script is not enough, as it should probably use wbinfo to
92 determine if an incoming SID is a user or group SID and then look up
93 the mapping in a table or use some other mechanism for mapping SIDs to
94 UIDs and etc.
95 Please be aware that the script is called with the _NO_WINBINDD
97 environment variable set to 1. This prevents recursive calls into
98 winbind from the script both via explicit calls to wbinfo and via
99 implicit calls via nss_winbind. For example a call to ls -l could
100 trigger such an infinite recursion.
101 It is safe to call wbinfo -n and wbinfo -s from within an idmap script.
103 To do so, the script must unset the _NO_WINBINDD environment variable
104 right before the call to wbinfo and set it to 1 again right after
105 wbinfo has returned to protect against the recursion.
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108 The original Samba software and related utilities were created by
109 Andrew Tridgell. Samba is now developed by the Samba Team as an Open
110 Source project similar to the way the Linux kernel is developed.
111Samba 4.17.5 01/26/2023 IDMAP_SCRIPT(8)