file. See also the \fB\-\-setuid\fR and \fB\-\-setgid\fR options.
.TP
\fB\-G\fR, \fB\-\-setgid\fR \fIgid\fR
-Set the group ID which will be used in the entered user namespace.
+Set the group ID which will be used in the entered namespace and drop
+supplementary groups.
+.BR nsenter (1)
+always sets GID for user namespaces, the default is 0.
.TP
\fB\-S\fR, \fB\-\-setuid\fR \fIuid\fR
-Set the user ID which will be used in the entered user namespace.
+Set the user ID which will be used in the entered namespace.
+.BR nsenter (1)
+always sets UID for user namespaces, the default is 0.
.TP
\fB\-r\fR, \fB\-\-root\fR[=\fIdirectory\fR]
Set the root directory. If no directory is specified, set the root directory to
fputs(_(" -n, --net [=<file>] enter network namespace\n"), out);
fputs(_(" -p, --pid [=<file>] enter pid namespace\n"), out);
fputs(_(" -U, --user [=<file>] enter user namespace\n"), out);
- fputs(_(" -S, --setuid <uid> set uid in user namespace\n"), out);
- fputs(_(" -G, --setgid <gid> set gid in user namespace\n"), out);
+ fputs(_(" -S, --setuid <uid> set uid in entered namespace\n"), out);
+ fputs(_(" -G, --setgid <gid> set gid in entered namespace\n"), out);
fputs(_(" -r, --root [=<dir>] set the root directory\n"), out);
fputs(_(" -w, --wd [=<dir>] set the working directory\n"), out);
fputs(_(" -F, --no-fork do not fork before exec'ing <program>\n"), out);
struct namespace_file *nsfile;
int c, namespaces = 0;
- bool do_rd = false, do_wd = false;
+ bool do_rd = false, do_wd = false, force_uid = false, force_gid = false;
int do_fork = -1; /* unknown yet */
uid_t uid = 0;
gid_t gid = 0;
break;
case 'S':
uid = strtoul_or_err(optarg, _("failed to parse uid"));
+ force_uid = true;
break;
case 'G':
gid = strtoul_or_err(optarg, _("failed to parse gid"));
+ force_gid = true;
break;
case 'F':
do_fork = 0;
if (do_fork == 1)
continue_as_child();
- if (namespaces & CLONE_NEWUSER) {
- if (setgroups(0, NULL)) /* drop supplementary groups */
+ /* for user namespaces we always set UID and GID (default is 0) */
+ if (namespaces & CLONE_NEWUSER)
+ force_uid = true, force_gid = true;
+
+ if (force_uid || force_gid) {
+ if (force_gid && setgroups(0, NULL)) /* drop supplementary groups */
err(EXIT_FAILURE, _("setgroups failed"));
- if (setgid(gid) < 0)
+ if (force_gid && setgid(gid) < 0) /* change GID */
err(EXIT_FAILURE, _("setgid failed"));
- if (setuid(uid) < 0)
+ if (force_uid && setuid(uid) < 0) /* change UID */
err(EXIT_FAILURE, _("setuid failed"));
}