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-rw-r--r--man/systemd-nspawn.xml59
-rw-r--r--src/nspawn/nspawn.c36
2 files changed, 55 insertions, 40 deletions
diff --git a/man/systemd-nspawn.xml b/man/systemd-nspawn.xml
index 4439d554a7..5ac54df81a 100644
--- a/man/systemd-nspawn.xml
+++ b/man/systemd-nspawn.xml
@@ -405,35 +405,36 @@
purposes (usually in the range beyond the host's UID/GID 65536). The parameter may be specified as follows:</para>
<orderedlist>
- <listitem><para>The value <literal>no</literal> turns off user namespacing. This is the default.</para></listitem>
-
- <listitem><para>The value <literal>yes</literal> (or the omission of a parameter) turns on user
- namespacing. 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>The value "pick" 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
- behaviour 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. 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 behaviour 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>Finally if one or two colon-separated numeric parameters are specified, user namespacing is
- turned on, too. The first parameter specifies the first host UID/GID to assign to the container, the second
- parameter specifies the 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 one or two colon-separated numers are specified, user namespacing is turned on. The first
+ parameter specifies the first host UID/GID to assign to the container, the second parameter specifies the
+ 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>
+
+ <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 behaviour 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. 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 behaviour 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
diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c
index e066c55dae..a173d171e1 100644
--- a/src/nspawn/nspawn.c
+++ b/src/nspawn/nspawn.c
@@ -913,14 +913,21 @@ static int parse_argv(int argc, char *argv[]) {
break;
- case ARG_PRIVATE_USERS:
+ case ARG_PRIVATE_USERS: {
+ int boolean = -1;
- if (streq_ptr(optarg, "no")) {
+ if (!optarg)
+ boolean = true;
+ else if (!in_charset(optarg, DIGITS))
+ /* do *not* parse numbers as booleans */
+ boolean = parse_boolean(optarg);
+
+ if (boolean == false) {
/* no: User namespacing off */
arg_userns_mode = USER_NAMESPACE_NO;
arg_uid_shift = UID_INVALID;
arg_uid_range = UINT32_C(0x10000);
- } else if (!optarg || streq(optarg, "yes")) {
+ } else if (boolean == true) {
/* yes: User namespacing on, UID range is read from root dir */
arg_userns_mode = USER_NAMESPACE_FIXED;
arg_uid_shift = UID_INVALID;
@@ -931,33 +938,40 @@ static int parse_argv(int argc, char *argv[]) {
arg_uid_shift = UID_INVALID;
arg_uid_range = UINT32_C(0x10000);
} else {
+ _cleanup_free_ char *buffer = NULL;
const char *range, *shift;
/* anything else: User namespacing on, UID range is explicitly configured */
range = strchr(optarg, ':');
if (range) {
- shift = strndupa(optarg, range - optarg);
+ buffer = strndup(optarg, range - optarg);
+ if (!buffer)
+ return log_oom();
+ shift = buffer;
range++;
r = safe_atou32(range, &arg_uid_range);
if (r < 0)
- return log_error_errno(r, "Failed to parse UID range '%s': %m", range);
- if (arg_uid_range == 0)
- return log_error_errno(EINVAL, "UID range cannot be 0.");
+ return log_error_errno(r, "Failed to parse UID range \"%s\": %m", range);
} else
shift = optarg;
- if (parse_uid(shift, &arg_uid_shift) < 0) {
- log_error("Failed to parse UID: %s", optarg);
- return -EINVAL;
- }
+ r = parse_uid(shift, &arg_uid_shift);
+ if (r < 0)
+ return log_error_errno(r, "Failed to parse UID \"%s\": %m", optarg);
arg_userns_mode = USER_NAMESPACE_FIXED;
}
+ if (arg_uid_range <= 0) {
+ log_error("UID range cannot be 0.");
+ return -EINVAL;
+ }
+
arg_settings_mask |= SETTING_USERNS;
break;
+ }
case 'U':
if (userns_supported()) {