From 5b4855ab73c162e3bc34e11f7080074c59a77841 Mon Sep 17 00:00:00 2001 From: Daan De Meyer Date: Thu, 19 Dec 2019 21:17:57 +0100 Subject: [PATCH] nspawn: Move --network-interface interfaces back to the host. --- src/nspawn/nspawn-network.c | 6 ++--- src/nspawn/nspawn-network.h | 2 +- src/nspawn/nspawn.c | 50 ++++++++++++++++++++++++++++++++----- 3 files changed, 48 insertions(+), 10 deletions(-) diff --git a/src/nspawn/nspawn-network.c b/src/nspawn/nspawn-network.c index 83ce62877a0..b31e3962d5d 100644 --- a/src/nspawn/nspawn-network.c +++ b/src/nspawn/nspawn-network.c @@ -438,7 +438,7 @@ int test_network_interface_initialized(const char *name) { return 0; } -int move_network_interfaces(pid_t pid, char **ifaces) { +int move_network_interfaces(int netns_fd, char **ifaces) { _cleanup_(sd_netlink_unrefp) sd_netlink *rtnl = NULL; char **i; int r; @@ -462,9 +462,9 @@ int move_network_interfaces(pid_t pid, char **ifaces) { if (r < 0) return log_error_errno(r, "Failed to allocate netlink message: %m"); - r = sd_netlink_message_append_u32(m, IFLA_NET_NS_PID, pid); + r = sd_netlink_message_append_u32(m, IFLA_NET_NS_FD, netns_fd); if (r < 0) - return log_error_errno(r, "Failed to append namespace PID to netlink message: %m"); + return log_error_errno(r, "Failed to append namespace fd to netlink message: %m"); r = sd_netlink_call(rtnl, m, 0, NULL); if (r < 0) diff --git a/src/nspawn/nspawn-network.h b/src/nspawn/nspawn-network.h index 7e83d10bfee..4999b172c4c 100644 --- a/src/nspawn/nspawn-network.h +++ b/src/nspawn/nspawn-network.h @@ -16,7 +16,7 @@ int remove_bridge(const char *bridge_name); int setup_macvlan(const char *machine_name, pid_t pid, char **ifaces); int setup_ipvlan(const char *machine_name, pid_t pid, char **ifaces); -int move_network_interfaces(pid_t pid, char **ifaces); +int move_network_interfaces(int netns_fd, char **ifaces); int veth_extra_parse(char ***l, const char *p); diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c index 13c91c40bfc..32294ed0029 100644 --- a/src/nspawn/nspawn.c +++ b/src/nspawn/nspawn.c @@ -4211,7 +4211,7 @@ static int run_container( int ifi = 0, r; ssize_t l; sigset_t mask_chld; - _cleanup_close_ int netns_fd = -1; + _cleanup_close_ int child_netns_fd = -1; assert_se(sigemptyset(&mask_chld) == 0); assert_se(sigaddset(&mask_chld, SIGCHLD) == 0); @@ -4270,11 +4270,11 @@ static int run_container( return log_error_errno(errno, "Failed to install SIGCHLD handler: %m"); if (arg_network_namespace_path) { - netns_fd = open(arg_network_namespace_path, O_RDONLY|O_NOCTTY|O_CLOEXEC); - if (netns_fd < 0) + child_netns_fd = open(arg_network_namespace_path, O_RDONLY|O_NOCTTY|O_CLOEXEC); + if (child_netns_fd < 0) return log_error_errno(errno, "Cannot open file %s: %m", arg_network_namespace_path); - r = fd_is_network_ns(netns_fd); + r = fd_is_network_ns(child_netns_fd); if (r == -EUCLEAN) log_debug_errno(r, "Cannot determine if passed network namespace path '%s' really refers to a network namespace, assuming it does.", arg_network_namespace_path); else if (r < 0) @@ -4319,7 +4319,7 @@ static int run_container( master_pty_socket_pair[1], unified_cgroup_hierarchy_socket_pair[1], fds, - netns_fd); + child_netns_fd); if (r < 0) _exit(EXIT_FAILURE); @@ -4421,7 +4421,15 @@ static int run_container( return log_error_errno(SYNTHETIC_ERRNO(ESRCH), "Child died too early"); } - r = move_network_interfaces(*pid, arg_network_interfaces); + if (child_netns_fd < 0) { + /* Make sure we have an open file descriptor to the child's network + * namespace so it stays alive even if the child exits. */ + r = namespace_open(*pid, NULL, NULL, &child_netns_fd, NULL, NULL); + if (r < 0) + return log_error_errno(r, "Failed to open child network namespace: %m"); + } + + r = move_network_interfaces(child_netns_fd, arg_network_interfaces); if (r < 0) return r; @@ -4667,6 +4675,36 @@ static int run_container( /* Normally redundant, but better safe than sorry */ (void) kill(*pid, SIGKILL); + if (arg_private_network) { + /* Move network interfaces back to the parent network namespace. We use `safe_fork` + * to avoid having to move the parent to the child network namespace. */ + r = safe_fork(NULL, FORK_RESET_SIGNALS|FORK_DEATHSIG|FORK_WAIT|FORK_LOG, NULL); + if (r < 0) + return r; + + if (r == 0) { + _cleanup_close_ int parent_netns_fd = -1; + + r = namespace_open(getpid(), NULL, NULL, &parent_netns_fd, NULL, NULL); + if (r < 0) { + log_error_errno(r, "Failed to open parent network namespace: %m"); + _exit(EXIT_FAILURE); + } + + r = namespace_enter(-1, -1, child_netns_fd, -1, -1); + if (r < 0) { + log_error_errno(r, "Failed to enter child network namespace: %m"); + _exit(EXIT_FAILURE); + } + + r = move_network_interfaces(parent_netns_fd, arg_network_interfaces); + if (r < 0) + log_error_errno(r, "Failed to move network interfaces back to parent network namespace: %m"); + + _exit(r < 0 ? EXIT_FAILURE : EXIT_SUCCESS); + } + } + r = wait_for_container(*pid, &container_status); *pid = 0; -- 2.47.3