sd-bus: implement sd_bus_get_owner_creds() for kdbus

kdbus learned a new ioctl to tell userspace about a bus creator's
credentials, which is what we need to implement sd_bus_get_owner_creds() for
kdbus.

Move the function from sd-bus.c to bus-control.c to be able to reuse
the bus_populate_creds_from_items() helper.

1 files changed, 66 insertions, 0 deletions

diff --git a/src/libsystemd/sd-bus/bus-control.c b/src/libsystemd/sd-bus/bus-control.c
index 96f59f9b3..a84b060b4 100644
--- a/src/libsystemd/sd-bus/bus-control.c
+++ b/src/libsystemd/sd-bus/bus-control.c
@@ -796,6 +796,72 @@ _public_ int sd_bus_get_name_creds(
                 return bus_get_name_creds_dbus1(bus, name, mask, creds);
 }
 
+_public_ int sd_bus_get_owner_creds(sd_bus *bus, uint64_t mask, sd_bus_creds **ret) {
+        _cleanup_bus_creds_unref_ sd_bus_creds *c = NULL;
+        pid_t pid = 0;
+        int r;
+
+        assert_return(bus, -EINVAL);
+        assert_return(mask <= _SD_BUS_CREDS_ALL, -ENOTSUP);
+        assert_return(ret, -EINVAL);
+        assert_return(!bus_pid_changed(bus), -ECHILD);
+
+        if (!BUS_IS_OPEN(bus->state))
+                return -ENOTCONN;
+
+        if (!bus->ucred_valid && !isempty(bus->label))
+                return -ENODATA;
+
+        c = bus_creds_new();
+        if (!c)
+                return -ENOMEM;
+
+        if (bus->ucred_valid) {
+                pid = c->pid = bus->ucred.pid;
+                c->uid = bus->ucred.uid;
+                c->gid = bus->ucred.gid;
+
+                c->mask |= (SD_BUS_CREDS_UID | SD_BUS_CREDS_PID | SD_BUS_CREDS_GID) & mask;
+        }
+
+        if (!isempty(bus->label) && (mask & SD_BUS_CREDS_SELINUX_CONTEXT)) {
+                c->label = strdup(bus->label);
+                if (!c->label) {
+                        sd_bus_creds_unref(c);
+                        return -ENOMEM;
+                }
+
+                c->mask |= SD_BUS_CREDS_SELINUX_CONTEXT;
+        }
+
+        if (bus->is_kernel) {
+                struct kdbus_cmd_info cmd = {};
+                struct kdbus_info *creator_info;
+
+                cmd.size = sizeof(cmd);
+                r = ioctl(bus->input_fd, KDBUS_CMD_BUS_CREATOR_INFO, &cmd);
+                if (r < 0)
+                        return -errno;
+
+                creator_info = (struct kdbus_info *) ((uint8_t *) bus->kdbus_buffer + cmd.offset);
+
+                r = bus_populate_creds_from_items(bus, creator_info, mask, c);
+                kernel_cmd_free(bus, cmd.offset);
+
+                if (r < 0)
+                        return r;
+        } else {
+                r = bus_creds_add_more(c, mask, pid, 0);
+                if (r < 0) {
+                        sd_bus_creds_unref(c);
+                        return r;
+                }
+        }
+
+        *ret = c;
+        return 0;
+}
+
 static int add_name_change_match(sd_bus *bus,
                                  uint64_t cookie,
                                  const char *name,