nsenter: allow to use --set{uid,gid} for all namespaces

Now it's possible to set UID and GID for user namespaces only. This
patch removes this restriction and allow to use --set{uid,gid} in all
cases. The default for user namespaces is still GID=0, UID=0.

Reported-by: Tomas Doran <bobtfish@bobtfish.net>
Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/sys-utils/nsenter.1 b/sys-utils/nsenter.1
index 998fd0cc0f626821c71c9aedad8abcdfb71bbb9d..487f731dc825e6c54d14846b12249a4906d91d16 100644 (file)
--- a/sys-utils/nsenter.1
+++ b/sys-utils/nsenter.1
@@ -126,10 +126,15 @@ the target process.  If file is specified, enter the user namespace specified by
 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

diff --git a/sys-utils/nsenter.c b/sys-utils/nsenter.c
index d57edc81b588065fd3b50151d4a01636c44d0b90..87c654939204d965c0e47d6903814f72b6356f35 100644 (file)
--- a/sys-utils/nsenter.c
+++ b/sys-utils/nsenter.c
@@ -73,8 +73,8 @@ static void usage(int status)
        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);
@@ -182,7 +182,7 @@ int main(int argc, char *argv[])
 
        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;
@@ -243,9 +243,11 @@ int main(int argc, char *argv[])
                        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;
@@ -328,12 +330,16 @@ int main(int argc, char *argv[])
        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"));
        }