net: restore macvlan by the same way with and without userns

If userns_restore_one_link() is called outside of usernsd,
it switches into the criu namespace and switches back before exiting.

v2: rid of the include of linux/net_namespace.h in criu/include/net.h,
    as well as the associated defines and feature checks

travis-ci: success for net: simplify restore of macvlan-s (rev2)
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>
Acked-by: Tycho Andersen <tycho.andersen@canonical.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

Makefile.config

@@ -18,7 +18,7 @@ export DEFINES += $(FEATURE_DEFINES)
 export CFLAGS += $(FEATURE_DEFINES)
 
 FEATURES_LIST	:= TCP_REPAIR STRLCPY STRLCAT PTRACE_PEEKSIGINFO \
-	SETPROCTITLE_INIT MEMFD TCP_REPAIR_WINDOW NET_NAMESPACE_H
+	SETPROCTITLE_INIT MEMFD TCP_REPAIR_WINDOW
 
 # $1 - config name
 define gen-feature-test

criu/cr-check.c

@@ -938,58 +938,6 @@ static int check_tcp_window(void)
 	return 0;
 }
 
-static int nsid_manip_cb(struct nlmsghdr *hdr, void *arg)
-{
-	return 0;
-}
-
-static int check_nsid_manip(void)
-{
-	int parent = -1, ret = -1, nlsk = -1;
-	struct {
-		struct nlmsghdr n;
-		struct rtgenmsg g;
-		char buf[1024];
-	} req;
-
-	parent = open("/proc/self/ns/net", O_RDONLY);
-	if (parent < 0) {
-		pr_perror("open");
-		return -1;
-	}
-
-	if (unshare(CLONE_NEWNET) < 0) {
-		pr_perror("unshare");
-		goto out;
-	}
-
-	nlsk = socket(PF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
-	if (nlsk < 0) {
-		pr_perror("socket");
-		goto out;
-	}
-
-	memset(&req, 0, sizeof(req));
-
-	req.n.nlmsg_len = NLMSG_LENGTH(sizeof(req.g));
-	req.n.nlmsg_flags = NLM_F_REQUEST|NLM_F_ACK;
-	req.n.nlmsg_type = RTM_GETNSID;
-	req.n.nlmsg_seq = CR_NLMSG_SEQ;
-
-	addattr_l(&req.n, sizeof(req), NETNSA_FD, &parent, sizeof(parent));
-	ret = do_rtnl_req(nlsk, &req, req.n.nlmsg_len, nsid_manip_cb, NULL, NULL);
-	if (ret < 0)
-		pr_err("can't manipulate netns ids\n");
-out:
-	if (nlsk > 0)
-		close(nlsk);
-	if (setns(parent, CLONE_NEWNET) < 0)
-		pr_warn("couldn't setns back to parent");
-	if (parent > 0)
-		close(parent);
-	return ret;
-}
-
 static int (*chk_feature)(void);
 
 /*
@@ -1090,7 +1038,6 @@ int cr_check(void)
 		ret |= check_clone_parent_vs_pid();
 		ret |= check_cgroupns();
 		ret |= check_tcp_window();
-		ret |= check_nsid_manip();
 	}
 
 	/*
@@ -1170,7 +1117,6 @@ static struct feature_list feature_list[] = {
 	{ "loginuid", check_loginuid },
 	{ "cgroupns", check_cgroupns },
 	{ "autofs", check_autofs },
-	{ "nsid_manip", check_nsid_manip },
 	{ NULL, NULL },
 };
 

criu/include/net.h

@@ -6,13 +6,6 @@
 #include "common/list.h"
 #include "external.h"
 
-#ifdef CONFIG_HAS_NET_NAMESPACE_H
-#include <linux/net_namespace.h>
-#else
-#define NETNSA_NSID	1
-#define NETNSA_FD	3
-#endif
-
 #ifndef RTM_GETNSID
 #define RTM_GETNSID		90
 #endif

criu/net.c

@@ -892,7 +892,6 @@ struct newlink_req {
  * request.
  */
 struct newlink_extras {
-	int netns_id;		/* IFLA_NET_NS_ID */
 	int link;		/* IFLA_LINK */
 	int target_netns;	/* IFLA_NET_NS_FD */
 };
@@ -917,9 +916,6 @@ static int populate_newlink_req(struct newlink_req *req, int msg_type, NetDevice
 	req->i.ifi_flags = nde->flags;
 
 	if (extras) {
-		if (extras->netns_id >= 0)
-			addattr_l(&req->h, sizeof(*req), IFLA_LINK_NETNSID, &extras->netns_id, sizeof(extras->netns_id));
-
 		if (extras->link >= 0)
 			addattr_l(&req->h, sizeof(*req), IFLA_LINK, &extras->link, sizeof(extras->link));
 
@@ -1102,108 +1098,39 @@ static int userns_restore_one_link(void *arg, int fd, pid_t pid)
 {
 	int nlsk, ret;
 	struct newlink_req *req = arg;
+	int ns_fd = get_service_fd(NS_FD_OFF), rst = -1;
+
+	if (!(root_ns_mask & CLONE_NEWUSER)) {
+		if (switch_ns_by_fd(ns_fd, &net_ns_desc, &rst))
+			return -1;
+	}
 
 	nlsk = socket(PF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
 	if (nlsk < 0) {
 		pr_perror("Can't create nlk socket");
-		return -1;
+		ret = -1;
+		goto out;
 	}
 
 	addattr_l(&req->h, sizeof(*req), IFLA_NET_NS_FD, &fd, sizeof(fd));
 
 	ret = do_rtnl_req(nlsk, req, req->h.nlmsg_len, restore_link_cb, NULL, NULL);
 	close(nlsk);
-	return ret;
-}
-
-static int get_nsid_cb(struct nlmsghdr *nlh, void *arg)
-{
-	struct rtgenmsg *rthdr;
-	struct rtattr *rta;
-	int len, *netnsid = arg;
-
-	rthdr = NLMSG_DATA(nlh);
-	len = nlh->nlmsg_len - NLMSG_SPACE(sizeof(*rthdr));
-
-	if (len < 0)
-		return -1;
-
-	rta = NETNS_RTA(rthdr);
-
-	while (RTA_OK(rta, len)) {
-		if (rta->rta_type == NETNSA_NSID)
-			*netnsid = *((int *) RTA_DATA(rta));
-		rta = RTA_NEXT(rta, len);
-	}
-
-	if (netnsid < 0) {
-		pr_err("Didn't get a netnsid back from netlink?\n");
-		return -1;
-	}
-
-	return 0;
-}
-
-static int get_criu_netnsid(int nlsk)
-{
-	static int netnsid = -1;
-	struct {
-		struct nlmsghdr n;
-		struct rtgenmsg g;
-		char buf[1024];
-	} req;
-	int ns_fd = get_service_fd(NS_FD_OFF), i;
-
-	if (netnsid > 0)
-		return netnsid;
-
-	for (i = 0; i < 10; i++) {
-		int ret;
-
-		memset(&req, 0, sizeof(req));
-
-		req.n.nlmsg_len = NLMSG_LENGTH(sizeof(req.g));
-		req.n.nlmsg_flags = NLM_F_REQUEST|NLM_F_ACK;
-		req.n.nlmsg_type = RTM_NEWNSID;
-		req.n.nlmsg_seq = CR_NLMSG_SEQ;
-
-		addattr_l(&req.n, sizeof(req), NETNSA_FD, &ns_fd, sizeof(ns_fd));
-		addattr_l(&req.n, sizeof(req), NETNSA_NSID, &i, sizeof(i));
-
-		ret = do_rtnl_req(nlsk, &req, req.n.nlmsg_len, NULL, NULL, NULL);
-		if (ret < 0) {
-			if (ret == -EEXIST) {
-				req.n.nlmsg_type = RTM_GETNSID;
-				ret = do_rtnl_req(nlsk, &req, req.n.nlmsg_len, get_nsid_cb, NULL, &netnsid);
-				if (ret < 0) {
-					pr_err("Couldn't get netnsid: %d\n", ret);
-					return -1;
-				}
-
-				return netnsid;
-			}
-			errno = -ret;
-			pr_perror("couldn't create new netnsid");
-			return -1;
-		}
 
-		netnsid = i;
-		return netnsid;
-	}
-
-	pr_err("tried to create too many netnsids\n");
-	return -1;
+out:
+	if (rst >= 0 && restore_ns(rst, &net_ns_desc) < 0)
+		ret = -1;
+	return ret;
 }
 
 static int restore_one_macvlan(NetDeviceEntry *nde, int nlsk, int criu_nlsk)
 {
 	struct newlink_extras extras = {
-		.netns_id = -1,
 		.link = -1,
 		.target_netns = -1,
 	};
 	char key[100], *val;
-	int my_netns = -1, ret = -1, s;
+	int my_netns = -1, ret = -1;
 
 	snprintf(key, sizeof(key), "macvlan[%s]", nde->name);
 	val = external_lookup_data(key);
@@ -1224,19 +1151,13 @@ static int restore_one_macvlan(NetDeviceEntry *nde, int nlsk, int criu_nlsk)
 	 */
 	extras.link = (int) (unsigned long) val;
 
-	extras.netns_id = get_criu_netnsid(nlsk);
-	if (extras.netns_id < 0) {
-		pr_err("failed to get criu's netnsid\n");
-		return -1;
-	}
-
 	my_netns = open_proc(PROC_SELF, "ns/net");
 	if (my_netns < 0) {
 		pr_perror("couldn't get my netns");
 		return -1;
 	}
 
-	if (root_ns_mask & CLONE_NEWUSER) {
+	{
 		struct newlink_req req;
 
 		if (populate_newlink_req(&req, RTM_NEWLINK, nde, macvlan_link_info, &extras) < 0)
@@ -1246,27 +1167,9 @@ static int restore_one_macvlan(NetDeviceEntry *nde, int nlsk, int criu_nlsk)
 			pr_err("couldn't restore macvlan interface %s via usernsd\n", nde->name);
 			goto out;
 		}
-	} else {
-		extras.target_netns = my_netns;
-		ret = restore_one_link(nde, criu_nlsk, macvlan_link_info, &extras);
-		if (ret < 0)
-			return -1;
 	}
 
-	/* We have to change the flags of the NDE manually here because
-	 * we used IFLA_LINK_NETNSID to restore it, which creates the
-	 * device and then shuts it down when it changes the device's
-	 * namespace, but doesn't start it back up when it goes to the
-	 * other namespace. So, we restore its state here.
-	 */
-	s = socket(AF_LOCAL, SOCK_STREAM, 0);
-	if (s < 0) {
-		pr_perror("couldn't open socket for flag changing");
-		goto out;
-	}
-	ret = changeflags(s, nde->name, nde->flags);
-	close(s);
-
+	ret = 0;
 out:
 	if (my_netns >= 0)
 		close(my_netns);
@@ -1301,7 +1204,7 @@ static int restore_link(NetDeviceEntry *nde, int nlsk, int criu_nlsk)
 
 static int restore_links(int pid, NetnsEntry **netns)
 {
-	int nlsk, criu_nlsk = -1, ret = -1, my_netns = -1, ns_fd = get_service_fd(NS_FD_OFF);
+	int nlsk, criu_nlsk = -1, ret = -1;
 	struct cr_img *img;
 	NetDeviceEntry *nde;
 
@@ -1316,38 +1219,6 @@ static int restore_links(int pid, NetnsEntry **netns)
 		return -1;
 	}
 
-	if (!(root_ns_mask & CLONE_NEWUSER)) {
-		/* FIXME: this whole dance is so we can have a netlink socket to criu's
-		 * netns in case we need it. It should really live on the ns_id struct,
-		 * but those aren't generated on restore yet.
-		 */
-		my_netns = open_proc(PROC_SELF, "ns/net");
-		if (my_netns < 0) {
-			pr_perror("couldn't open my netns");
-			goto out;
-		}
-
-		if (setns(ns_fd, CLONE_NEWNET) < 0) {
-			close(my_netns);
-			pr_perror("couldn't setns to parent ns");
-			goto out;
-		}
-
-		criu_nlsk = socket(PF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
-		ret = setns(my_netns, CLONE_NEWNET);
-		close(my_netns);
-
-		if (ret < 0) {
-			pr_perror("Can't setns back my netns");
-			goto out;
-		}
-
-		if (criu_nlsk < 0) {
-			pr_perror("Can't create nlk socket");
-			goto out;
-		}
-	}
-
 	while (1) {
 		NetnsEntry **def_netns = netns;
 
@@ -1384,9 +1255,6 @@ exit:
 			break;
 	}
 
-out:
-	if (criu_nlsk >= 0)
-		close(criu_nlsk);
 	close(nlsk);
 	close_image(img);
 	return ret;

scripts/feature-tests.mak

@@ -88,14 +88,3 @@ int main(int argc, char *argv[], char *envp[])
 }
 
 endef
-
-define FEATURE_TEST_NET_NAMESPACE_H
-
-#include <linux/net_namespace.h>
-
-int main(int argc, char **argv)
-{
-        return 0;
-}
-
-endef

test/zdtm/static/macvlan.desc

-{'flavor': 'ns uns', 'deps': [ '/bin/sh', '/usr/bin/sort', '/bin/grep', '/sbin/ip', '/usr/bin/diff'], 'flags': 'suid', 'ropts': '--external macvlan[zdtmmvlan0]:zdtmbr0', 'feature': 'nsid_manip'}
+{'flavor': 'ns uns', 'deps': [ '/bin/sh', '/usr/bin/sort', '/bin/grep', '/sbin/ip', '/usr/bin/diff'], 'flags': 'suid', 'ropts': '--external macvlan[zdtmmvlan0]:zdtmbr0'}