bus: add API call to create bus connection to the system bus of local containers

Also, add support for this to machinectl, so that we can enumerate the
machines that run inside a container. We must go deeper!

1 files changed, 128 insertions, 0 deletions

diff --git a/src/libsystemd-bus/bus-container.c b/src/libsystemd-bus/bus-container.c
new file mode 100644
index 0000000000..eac1863244
--- /dev/null
+++ b/src/libsystemd-bus/bus-container.c
@@ -0,0 +1,128 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2013 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <unistd.h>
+#include <fcntl.h>
+
+#include "util.h"
+#include "fileio.h"
+#include "bus-internal.h"
+#include "bus-socket.h"
+#include "bus-container.h"
+
+int bus_container_connect(sd_bus *b) {
+        _cleanup_free_ char *p = NULL, *s = NULL, *ns = NULL, *root = NULL, *class = NULL;
+        _cleanup_close_ int nsfd = -1, rootfd = -1;
+        siginfo_t si;
+        pid_t leader, child;
+        int r;
+
+        assert(b);
+        assert(b->input_fd < 0);
+        assert(b->output_fd < 0);
+
+        p = strappend("/run/systemd/machines/", b->machine);
+        if (!p)
+                return -ENOMEM;
+
+        r = parse_env_file(p, NEWLINE, "LEADER", &s, "CLASS", &class, NULL);
+        if (r < 0)
+                return r;
+        if (!s)
+                return -EIO;
+
+        if (!streq_ptr(class, "container"))
+                return -EIO;
+
+        r = parse_pid(s, &leader);
+        if (r < 0)
+                return r;
+        if (leader <= 1)
+                return -EIO;
+
+        r = asprintf(&ns, "/proc/%lu/ns/mnt", (unsigned long) leader);
+        if (r < 0)
+                return -ENOMEM;
+
+        nsfd = open(ns, O_RDONLY|O_NOCTTY|O_CLOEXEC);
+        if (nsfd < 0)
+                return -errno;
+
+        r = asprintf(&root, "/proc/%lu/root", (unsigned long) leader);
+        if (r < 0)
+                return -ENOMEM;
+
+        rootfd = open(root, O_RDONLY|O_NOCTTY|O_CLOEXEC);
+        if (rootfd < 0)
+                return -errno;
+
+        b->input_fd = socket(b->sockaddr.sa.sa_family, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
+        if (b->input_fd < 0)
+                return -errno;
+
+        b->output_fd = b->input_fd;
+
+        r = bus_socket_setup(b);
+        if (r < 0)
+                return r;
+
+        child = fork();
+        if (child < 0)
+                return -errno;
+
+        if (child == 0) {
+                r = setns(nsfd, CLONE_NEWNS);
+                if (r < 0)
+                        _exit(255);
+
+                if (fchdir(rootfd) < 0)
+                        _exit(255);
+
+                if (chroot(".") < 0)
+                        _exit(255);
+
+
+                r = connect(b->input_fd, &b->sockaddr.sa, b->sockaddr_size);
+                if (r < 0) {
+                        if (errno == EINPROGRESS)
+                                _exit(1);
+
+                        _exit(255);
+                }
+
+                _exit(0);
+        }
+
+        r = wait_for_terminate(child, &si);
+        if (r < 0)
+                return r;
+
+        if (si.si_code != CLD_EXITED)
+                return -EIO;
+
+        if (si.si_status == 1)
+                return 1;
+
+        if (si.si_status != 0)
+                return -EIO;
+
+        return bus_socket_start_auth(b);
+}