1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
|
<?xml version="1.0" encoding="UTF-8"?>
<!--
SPDX-FileCopyrightText: 2013 Eric W. Biederman
SPDX-License-Identifier: BSD-3-Clause
-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
<!-- SHADOW-CONFIG-HERE -->
]>
<refentry id='newgidmap.1'>
<refentryinfo>
<author>
<firstname>Eric</firstname>
<surname>Biederman</surname>
<contrib>Creation, 2013</contrib>
</author>
</refentryinfo>
<refmeta>
<refentrytitle>newgidmap</refentrytitle>
<manvolnum>1</manvolnum>
<refmiscinfo class="sectdesc">User Commands</refmiscinfo>
<refmiscinfo class="source">shadow-utils</refmiscinfo>
<refmiscinfo class="version">&SHADOW_UTILS_VERSION;</refmiscinfo>
</refmeta>
<refnamediv id='name'>
<refname>newgidmap</refname>
<refpurpose>set the gid mapping of a user namespace</refpurpose>
</refnamediv>
<refsynopsisdiv id='synopsis'>
<cmdsynopsis>
<command>newgidmap</command>
<arg choice='plain'>
<replaceable>pid</replaceable>
</arg>
<arg choice='plain'>
<replaceable>gid</replaceable>
</arg>
<arg choice='plain'>
<replaceable>lowergid</replaceable>
</arg>
<arg choice='plain'>
<replaceable>count</replaceable>
</arg>
<arg choice='opt'>
<arg choice='plain'>
<replaceable>gid</replaceable>
</arg>
<arg choice='plain'>
<replaceable>lowergid</replaceable>
</arg>
<arg choice='plain'>
<replaceable>count</replaceable>
</arg>
<arg choice='opt'>
<replaceable>...</replaceable>
</arg>
</arg>
</cmdsynopsis>
</refsynopsisdiv>
<refsect1 id='description'>
<title>DESCRIPTION</title>
<para>
The <command>newgidmap</command> sets <filename>/proc/[pid]/gid_map</filename>
based on its command line arguments and the gids allowed. Subgid
delegation can either be managed via <filename>/etc/subgid</filename>
or through the configured NSS subid module. These options are mutually
exclusive.
</para>
<para>
Note that the root group is not exempted from the requirement for a valid
<filename>/etc/subgid</filename> entry.
</para>
<para>
After the pid argument, <command>newgidmap</command> expects sets of 3 integers:
<variablelist>
<varlistentry>
<term>gid</term>
<listitem>
<para>
Beginning of the range of GIDs inside the user namespace.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>lowergid</term>
<listitem>
<para>
Beginning of the range of GIDs outside the user namespace.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>count</term>
<listitem>
<para>
Length of the ranges (both inside and outside the user namespace).
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
<para>
<command>newgidmap</command> verifies that the caller is the owner
of the process indicated by <option>pid</option> and that for each
of the above sets, each of the GIDs in the range [lowergid,
lowergid+count) is allowed to the caller according to
<filename>/etc/subgid</filename> before setting
<filename>/proc/[pid]/gid_map</filename>.
</para>
<para>
Note that newgidmap may be used only once for a given process.
</para>
<para>
Instead of an integer process id, the first argument may be
specified as <replaceable>fd:N</replaceable>, where the integer N
is the file descriptor number for the calling process's opened
file descriptor for the directory <filename>/proc/[pid]</filename>.
In this case, <command>newgidmap</command> will use
<refentrytitle>openat</refentrytitle><manvolnum>2</manvolnum>
to open the <filename>gid_map</filename> file under that
directory, avoiding a TOCTTOU in case the process exits and
the pid is immediately reused.
</para>
</refsect1>
<refsect1 id='options'>
<title>OPTIONS</title>
<para>
There currently are no options to the <command>newgidmap</command> command.
</para>
<variablelist remap='IP'>
</variablelist>
</refsect1>
<refsect1 id='files'>
<title>FILES</title>
<variablelist>
<varlistentry>
<term><filename>/etc/subgid</filename></term>
<listitem>
<para>List of user's subordinate group IDs.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>/proc/[pid]/gid_map</filename></term>
<listitem>
<para>Mapping of gids from one between user namespaces.</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 id='see_also'>
<title>SEE ALSO</title>
<para>
<citerefentry>
<refentrytitle>login.defs</refentrytitle><manvolnum>5</manvolnum>
</citerefentry>,
<citerefentry>
<refentrytitle>newusers</refentrytitle><manvolnum>8</manvolnum>
</citerefentry>,
<citerefentry>
<refentrytitle>subgid</refentrytitle><manvolnum>5</manvolnum>
</citerefentry>,
<citerefentry>
<refentrytitle>useradd</refentrytitle><manvolnum>8</manvolnum>
</citerefentry>,
<citerefentry>
<refentrytitle>userdel</refentrytitle><manvolnum>8</manvolnum>
</citerefentry>,
<citerefentry>
<refentrytitle>usermod</refentrytitle><manvolnum>8</manvolnum>
</citerefentry>.
</para>
</refsect1>
</refentry>
|