nspawn: set up a kdbus namespace when starting a container

8 files changed, 84 insertions, 8 deletions

diff --git a/src/core/manager.c b/src/core/manager.c
index a168589e38..7de0b26811 100644
--- a/src/core/manager.c
+++ b/src/core/manager.c
@@ -421,7 +421,7 @@ static int manager_setup_kdbus(Manager *m) {
         if (m->running_as == SYSTEMD_USER && getenv("DBUS_SESSION_BUS_ADDRESS"))
                 return 0;
 
-        m->kdbus_fd = bus_kernel_create(m->running_as == SYSTEMD_SYSTEM ? "system" : "user", &p);
+        m->kdbus_fd = bus_kernel_create_bus(m->running_as == SYSTEMD_SYSTEM ? "system" : "user", &p);
         if (m->kdbus_fd < 0) {
                 log_debug("Failed to set up kdbus: %s", strerror(-m->kdbus_fd));
                 return m->kdbus_fd;
diff --git a/src/libsystemd-bus/bus-kernel.c b/src/libsystemd-bus/bus-kernel.c
index 51e882c73d..09e084a02f 100644
--- a/src/libsystemd-bus/bus-kernel.c
+++ b/src/libsystemd-bus/bus-kernel.c
@@ -1042,7 +1042,7 @@ int kdbus_translate_attach_flags(uint64_t mask, uint64_t *kdbus_mask) {
         return 0;
 }
 
-int bus_kernel_create(const char *name, char **s) {
+int bus_kernel_create_bus(const char *name, char **s) {
         struct kdbus_cmd_bus_make *make;
         struct kdbus_item *n;
         int fd;
@@ -1088,3 +1088,47 @@ int bus_kernel_create(const char *name, char **s) {
 
         return fd;
 }
+
+int bus_kernel_create_namespace(const char *name, char **s) {
+        struct kdbus_cmd_ns_make *make;
+        struct kdbus_item *n;
+        int fd;
+
+        assert(name);
+        assert(s);
+
+        fd = open("/dev/kdbus/control", O_RDWR|O_NOCTTY|O_CLOEXEC);
+        if (fd < 0)
+                return -errno;
+
+        make = alloca0(ALIGN8(offsetof(struct kdbus_cmd_ns_make, items) +
+                              offsetof(struct kdbus_item, str) +
+                              strlen(name) + 1));
+
+        n = make->items;
+        strcpy(n->str, name);
+        n->size = offsetof(struct kdbus_item, str) + strlen(n->str) + 1;
+        n->type = KDBUS_MAKE_NAME;
+
+        make->size = ALIGN8(offsetof(struct kdbus_cmd_ns_make, items) + n->size);
+        make->flags = KDBUS_MAKE_POLICY_OPEN;
+
+        if (ioctl(fd, KDBUS_CMD_NS_MAKE, make) < 0) {
+                close_nointr_nofail(fd);
+                return -errno;
+        }
+
+        if (s) {
+                char *p;
+
+                p = strappend("/dev/kdbus/", name);
+                if (!p) {
+                        close_nointr_nofail(fd);
+                        return -ENOMEM;
+                }
+
+                *s = p;
+        }
+
+        return fd;
+}
diff --git a/src/libsystemd-bus/bus-kernel.h b/src/libsystemd-bus/bus-kernel.h
index 746ab227a4..92d3888ed5 100644
--- a/src/libsystemd-bus/bus-kernel.h
+++ b/src/libsystemd-bus/bus-kernel.h
@@ -60,7 +60,8 @@ int bus_kernel_take_fd(sd_bus *b);
 int bus_kernel_write_message(sd_bus *bus, sd_bus_message *m);
 int bus_kernel_read_message(sd_bus *bus);
 
-int bus_kernel_create(const char *name, char **s);
+int bus_kernel_create_bus(const char *name, char **s);
+int bus_kernel_create_namespace(const char *name, char **s);
 
 int bus_kernel_pop_memfd(sd_bus *bus, void **address, size_t *size);
 void bus_kernel_push_memfd(sd_bus *bus, int fd, void *address, size_t size);
diff --git a/src/libsystemd-bus/test-bus-kernel-benchmark.c b/src/libsystemd-bus/test-bus-kernel-benchmark.c
index 6afae7f487..010a161328 100644
--- a/src/libsystemd-bus/test-bus-kernel-benchmark.c
+++ b/src/libsystemd-bus/test-bus-kernel-benchmark.c
@@ -239,7 +239,7 @@ int main(int argc, char *argv[]) {
 
         assert_se(arg_loop_usec > 0);
 
-        bus_ref = bus_kernel_create("deine-mutter", &bus_name);
+        bus_ref = bus_kernel_create_bus("deine-mutter", &bus_name);
         if (bus_ref == -ENOENT)
                 exit(EXIT_TEST_SKIP);
 
diff --git a/src/libsystemd-bus/test-bus-kernel-bloom.c b/src/libsystemd-bus/test-bus-kernel-bloom.c
index dcf048338f..62983eacc8 100644
--- a/src/libsystemd-bus/test-bus-kernel-bloom.c
+++ b/src/libsystemd-bus/test-bus-kernel-bloom.c
@@ -42,7 +42,7 @@ static void test_one(
         sd_bus *a, *b;
         int r;
 
-        bus_ref = bus_kernel_create("deine-mutter", &bus_name);
+        bus_ref = bus_kernel_create_bus("deine-mutter", &bus_name);
         if (bus_ref == -ENOENT)
                 exit(EXIT_TEST_SKIP);
 
diff --git a/src/libsystemd-bus/test-bus-kernel.c b/src/libsystemd-bus/test-bus-kernel.c
index 04dbc998dc..23b185d3fe 100644
--- a/src/libsystemd-bus/test-bus-kernel.c
+++ b/src/libsystemd-bus/test-bus-kernel.c
@@ -42,7 +42,7 @@ int main(int argc, char *argv[]) {
 
         log_set_max_level(LOG_DEBUG);
 
-        bus_ref = bus_kernel_create("deine-mutter", &bus_name);
+        bus_ref = bus_kernel_create_bus("deine-mutter", &bus_name);
         if (bus_ref == -ENOENT)
                 return EXIT_TEST_SKIP;
 
diff --git a/src/libsystemd-bus/test-bus-zero-copy.c b/src/libsystemd-bus/test-bus-zero-copy.c
index 032449a5d8..92a7398a78 100644
--- a/src/libsystemd-bus/test-bus-zero-copy.c
+++ b/src/libsystemd-bus/test-bus-zero-copy.c
@@ -51,7 +51,7 @@ int main(int argc, char *argv[]) {
 
         log_set_max_level(LOG_DEBUG);
 
-        bus_ref = bus_kernel_create("deine-mutter", &bus_name);
+        bus_ref = bus_kernel_create_bus("deine-mutter", &bus_name);
         if (bus_ref == -ENOENT)
                 return EXIT_TEST_SKIP;
 
diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c
index cd757c497b..dd7337bc91 100644
--- a/src/nspawn/nspawn.c
+++ b/src/nspawn/nspawn.c
@@ -61,6 +61,7 @@
 #include "bus-util.h"
 #include "bus-error.h"
 #include "ptyfwd.h"
+#include "bus-kernel.h"
 
 #ifndef TTY_GID
 #define TTY_GID 5
@@ -927,6 +928,26 @@ static int setup_journal(const char *directory) {
         return 0;
 }
 
+static int setup_kdbus(const char *dest, const char *path) {
+        const char *p;
+
+        if (!path)
+                return 0;
+
+        p = strappenda(dest, "/dev/kdbus");
+        if (mkdir(p, 0755) < 0) {
+                log_error("Failed to create kdbus path: %m");
+                return  -errno;
+        }
+
+        if (mount(path, p, "bind", MS_BIND, NULL) < 0) {
+                log_error("Failed to mount kdbus namespace path: %m");
+                return -errno;
+        }
+
+        return 0;
+}
+
 static int drop_capabilities(void) {
         return capability_bounding_set_drop(~arg_retain, false);
 }
@@ -1032,12 +1053,13 @@ static bool audit_enabled(void) {
 int main(int argc, char *argv[]) {
         pid_t pid = 0;
         int r = EXIT_FAILURE, k;
-        _cleanup_close_ int master = -1;
+        _cleanup_close_ int master = -1, kdbus_fd = -1;
         int n_fd_passed;
         const char *console = NULL;
         sigset_t mask;
         _cleanup_close_pipe_ int kmsg_socket_pair[2] = { -1, -1 };
         _cleanup_fdset_free_ FDSet *fds = NULL;
+        _cleanup_free_ char *kdbus_namespace = NULL;
 
         log_parse_environment();
         log_open();
@@ -1138,6 +1160,12 @@ int main(int argc, char *argv[]) {
                 goto finish;
         }
 
+        kdbus_fd = bus_kernel_create_namespace(arg_machine, &kdbus_namespace);
+        if (r < 0)
+                log_debug("Failed to create kdbus namespace: %s", strerror(-r));
+        else
+                log_debug("Successfully created kdbus namespace as %s", kdbus_namespace);
+
         if (socketpair(AF_UNIX, SOCK_DGRAM|SOCK_NONBLOCK|SOCK_CLOEXEC, 0, kmsg_socket_pair) < 0) {
                 log_error("Failed to create kmsg socket pair.");
                 goto finish;
@@ -1289,6 +1317,9 @@ int main(int argc, char *argv[]) {
                         if (mount_binds(arg_directory, arg_bind_ro, MS_RDONLY) < 0)
                                 goto child_fail;
 
+                        if (setup_kdbus(arg_directory, kdbus_namespace) < 0)
+                                goto child_fail;
+
                         if (chdir(arg_directory) < 0) {
                                 log_error("chdir(%s) failed: %m", arg_directory);
                                 goto child_fail;