diff options
Diffstat (limited to 'man')
| -rw-r--r-- | man/systemd-nspawn.xml | 94 | ||||
| -rw-r--r-- | man/systemd.nspawn.xml | 10 |
2 files changed, 63 insertions, 41 deletions
diff --git a/man/systemd-nspawn.xml b/man/systemd-nspawn.xml index c4732507df..403636545a 100644 --- a/man/systemd-nspawn.xml +++ b/man/systemd-nspawn.xml @@ -696,32 +696,41 @@ number of host UIDs/GIDs to assign to the container. If the second parameter is omitted, 65536 UIDs/GIDs are assigned.</para></listitem> - <listitem><para>If the parameter is omitted, or true, user namespacing is turned on. The UID/GID range to - use is determined automatically from the file ownership of the root directory of the container's directory - tree. To use this option, make sure to prepare the directory tree in advance, and ensure that all files and - directories in it are owned by UIDs/GIDs in the range you'd like to use. Also, make sure that used file ACLs - exclusively reference UIDs/GIDs in the appropriate range. If this mode is used the number of UIDs/GIDs - assigned to the container for use is 65536, and the UID/GID of the root directory must be a multiple of - 65536.</para></listitem> - - <listitem><para>If the parameter is false, user namespacing is turned off. This is the default.</para> + <listitem><para>If the parameter is <literal>yes</literal>, user namespacing is turned on. The + UID/GID range to use is determined automatically from the file ownership of the root directory of + the container's directory tree. To use this option, make sure to prepare the directory tree in + advance, and ensure that all files and directories in it are owned by UIDs/GIDs in the range you'd + like to use. Also, make sure that used file ACLs exclusively reference UIDs/GIDs in the appropriate + range. In this mode, the number of UIDs/GIDs assigned to the container is 65536, and the owner + UID/GID of the root directory must be a multiple of 65536.</para></listitem> + + <listitem><para>If the parameter is <literal>no</literal>, user namespacing is turned off. This is + the default.</para> </listitem> - <listitem><para>The special value <literal>pick</literal> turns on user namespacing. In this case the UID/GID - range is automatically chosen. As first step, the file owner of the root directory of the container's - directory tree is read, and it is checked that it is currently not used by the system otherwise (in - particular, that no other container is using it). If this check is successful, the UID/GID range determined - this way is used, similar to the behavior if "yes" is specified. If the check is not successful (and thus - the UID/GID range indicated in the root directory's file owner is already used elsewhere) a new – currently - unused – UID/GID range of 65536 UIDs/GIDs is randomly chosen between the host UID/GIDs of 524288 and - 1878982656, always starting at a multiple of 65536, and, if possible, consistently hashed from the machine - name. This setting implies - <option>--private-users-chown</option> (see below), which has the effect that the files and directories in - the container's directory tree will be owned by the appropriate users of the range picked. Using this option - makes user namespace behavior fully automatic. Note that the first invocation of a previously unused - container image might result in picking a new UID/GID range for it, and thus in the (possibly expensive) file - ownership adjustment operation. However, subsequent invocations of the container will be cheap (unless of - course the picked UID/GID range is assigned to a different use by then).</para></listitem> + <listitem><para>If the parameter is <literal>identity</literal>, user namespacing is employed with + an identity mapping for the first 65536 UIDs/GIDs. This is mostly equivalent to + <option>--private-users=0:65536</option>. While it does not provide UID/GID isolation, since all + host and container UIDs/GIDs are chosen identically it does provide process capability isolation, + and hence is often a good choice if proper user namespacing with distinct UID maps is not + appropriate.</para></listitem> + + <listitem><para>The special value <literal>pick</literal> turns on user namespacing. In this case + the UID/GID range is automatically chosen. As first step, the file owner UID/GID of the root + directory of the container's directory tree is read, and it is checked that no other container is + currently using it. If this check is successful, the UID/GID range determined this way is used, + similar to the behavior if <literal>yes</literal> is specified. If the check is not successful (and + thus the UID/GID range indicated in the root directory's file owner is already used elsewhere) a + new – currently unused – UID/GID range of 65536 UIDs/GIDs is randomly chosen between the host + UID/GIDs of 524288 and 1878982656, always starting at a multiple of 65536, and, if possible, + consistently hashed from the machine name. This setting implies + <option>--private-users-ownership=auto</option> (see below), which possibly has the effect that the + files and directories in the container's directory tree will be owned by the appropriate users of + the range picked. Using this option makes user namespace behavior fully automatic. Note that the + first invocation of a previously unused container image might result in picking a new UID/GID range + for it, and thus in the (possibly expensive) file ownership adjustment operation. However, + subsequent invocations of the container will be cheap (unless of course the picked UID/GID range is + assigned to a different use by then).</para></listitem> </orderedlist> <para>It is recommended to assign at least 65536 UIDs/GIDs to each container, so that the usable UID/GID range in the @@ -747,31 +756,44 @@ </varlistentry> <varlistentry> - <term><option>--private-users-chown</option></term> - - <listitem><para>If specified, all files and directories in the container's directory tree will be - adjusted so that they are owned by the appropriate UIDs/GIDs selected for the container (see above). - This operation is potentially expensive, as it involves iterating through the full directory tree of - the container. Besides actual file ownership, file ACLs are adjusted as well.</para> - - <para>This option is implied if <option>--private-users=pick</option> is used. This option has no effect if - user namespacing is not used.</para></listitem> + <term><option>--private-users-ownership=</option></term> + + <listitem><para>Controls how to adjust the container image's UIDs and GIDs to match the UID/GID range + chosen with <option>--private-users=</option>, see above. Takes one of <literal>off</literal> (to + leave the image as is), <literal>chown</literal> (to recursively <function>chown()</function> the + container's directory tree as needed), <literal>map</literal> (in order to use transparent ID mapping + mounts) or <literal>auto</literal> for automatically using <literal>map</literal> where available and + <literal>chown</literal> where not.</para> + + <para>If <literal>chown</literal> is selected, all files and directories in the container's directory + tree will be adjusted so that they are owned by the appropriate UIDs/GIDs selected for the container + (see above). This operation is potentially expensive, as it involves iterating through the full + directory tree of the container. Besides actual file ownership, file ACLs are adjusted as + well.</para> + + <para>Typically <literal>map</literal> is the best choice, since it transparently maps UIDs/GIDs in + memory as needed without modifying the image, and without requiring an expensive recursive adjustment + operation. However, it is not available for all file systems, currently.</para> + + <para>The <option>--private-users-ownership=auto</option> option is implied if + <option>--private-users=pick</option> is used. This option has no effect if user namespacing is not + used.</para></listitem> </varlistentry> <varlistentry> <term><option>-U</option></term> <listitem><para>If the kernel supports the user namespaces feature, equivalent to - <option>--private-users=pick --private-users-chown</option>, otherwise equivalent to + <option>--private-users=pick --private-users-ownership=auto</option>, otherwise equivalent to <option>--private-users=no</option>.</para> <para>Note that <option>-U</option> is the default if the <filename>systemd-nspawn@.service</filename> template unit file is used.</para> - <para>Note: it is possible to undo the effect of <option>--private-users-chown</option> (or + <para>Note: it is possible to undo the effect of <option>--private-users-ownership=chown</option> (or <option>-U</option>) on the file system by redoing the operation with the first UID of 0:</para> - <programlisting>systemd-nspawn … --private-users=0 --private-users-chown</programlisting> + <programlisting>systemd-nspawn … --private-users=0 --private-users-ownership=chown</programlisting> </listitem> </varlistentry> diff --git a/man/systemd.nspawn.xml b/man/systemd.nspawn.xml index 6ad0e1a101..186616b6ad 100644 --- a/man/systemd.nspawn.xml +++ b/man/systemd.nspawn.xml @@ -452,12 +452,12 @@ </varlistentry> <varlistentry> - <term><varname>PrivateUsersChown=</varname></term> + <term><varname>PrivateUsersOwnership=</varname></term> - <listitem><para>Configures whether the ownership of the files and directories in the container tree shall be - adjusted to the UID/GID range used, if necessary and user namespacing is enabled. This is equivalent to the - <option>--private-users-chown</option> command line switch. This option is privileged (see - above). </para></listitem> + <listitem><para>Configures whether the ownership of the files and directories in the container tree + shall be adjusted to the UID/GID range used, if necessary and user namespacing is enabled. This is + equivalent to the <option>--private-users-ownership=</option> command line switch. This option is + privileged (see above).</para></listitem> </varlistentry> </variablelist> |