[2/2] net: restore macvlan by the same way with and without userns

Submitted by Andrei Vagin on Oct. 27, 2016, 6:18 a.m.

Details

Message ID 1477549133-7762-3-git-send-email-avagin@openvz.org
State Superseded
Series "net: simplify restore of macvlan-s"
Headers show

Commit Message

Andrei Vagin Oct. 27, 2016, 6:18 a.m.
From: Andrei Vagin <avagin@virtuozzo.com>

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

Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>
---
 criu/net.c | 147 ++++++-------------------------------------------------------
 1 file changed, 14 insertions(+), 133 deletions(-)

Patch hide | download patch | download mbox

diff --git a/criu/net.c b/criu/net.c
index 35388ee..6741ba9 100644
--- a/criu/net.c
+++ b/criu/net.c
@@ -891,7 +891,6 @@  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 */
 };
@@ -916,9 +915,6 @@  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));
 
@@ -1101,103 +1097,34 @@  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,
 	};
@@ -1223,19 +1150,13 @@  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)
@@ -1245,11 +1166,6 @@  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
@@ -1300,7 +1216,7 @@  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;
 
@@ -1315,38 +1231,6 @@  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;
 
@@ -1383,9 +1267,6 @@  exit:
 			break;
 	}
 
-out:
-	if (criu_nlsk >= 0)
-		close(criu_nlsk);
 	close(nlsk);
 	close_image(img);
 	return ret;

Comments

Tycho Andersen Oct. 27, 2016, 2:47 p.m.
On Thu, Oct 27, 2016 at 09:18:53AM +0300, Andrei Vagin wrote:
> From: Andrei Vagin <avagin@virtuozzo.com>
> 
> If userns_restore_one_link() is called outside of usernsd,
> it switches into the criu namespace and switches back before exiting.

Oh, nice. I guess the kernel only does this perms check when you
specify IFLA_LINK_NETNSID, even if that points to the same netns as
struct net for the socket.

Anyway, looks good to me,

Acked-by: Tycho Andersen <tycho.andersen@canonical.com>

I think this means we can also get rid of the include of
linux/net_namespace.h in criu/include/net.h, as well as the associated
defines and feature checks, right?

I think it also means we don't have to do changeflags at the end,
because the kernel only calls dev_change_net_namespace() if
IFLA_LINK_NETNSID was specified.

Tycho

> Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>
> ---
>  criu/net.c | 147 ++++++-------------------------------------------------------
>  1 file changed, 14 insertions(+), 133 deletions(-)
> 
> diff --git a/criu/net.c b/criu/net.c
> index 35388ee..6741ba9 100644
> --- a/criu/net.c
> +++ b/criu/net.c
> @@ -891,7 +891,6 @@ 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 */
>  };
> @@ -916,9 +915,6 @@ 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));
>  
> @@ -1101,103 +1097,34 @@ 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,
>  	};
> @@ -1223,19 +1150,13 @@ 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)
> @@ -1245,11 +1166,6 @@ 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
> @@ -1300,7 +1216,7 @@ 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;
>  
> @@ -1315,38 +1231,6 @@ 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;
>  
> @@ -1383,9 +1267,6 @@ exit:
>  			break;
>  	}
>  
> -out:
> -	if (criu_nlsk >= 0)
> -		close(criu_nlsk);
>  	close(nlsk);
>  	close_image(img);
>  	return ret;
> -- 
> 2.7.4
>