netns: fix GFP flags in rtnl_net_notifyid()

In rtnl_net_notifyid(), we certainly can't pass a null GFP flag to
rtnl_notify(). A GFP_KERNEL flag would be fine in most circumstances,
but there are a few paths calling rtnl_net_notifyid() from atomic
context or from RCU critical sections. The later also precludes the use
of gfp_any() as it wouldn't detect the RCU case. Also, the nlmsg_new()
call is wrong too, as it uses GFP_KERNEL unconditionally.

Therefore, we need to pass the GFP flags as parameter and propagate it
through function calls until the proper flags can be determined.

In most cases, GFP_KERNEL is fine. The exceptions are:
  * openvswitch: ovs_vport_cmd_get() and ovs_vport_cmd_dump()
    indirectly call rtnl_net_notifyid() from RCU critical section,

  * rtnetlink: rtmsg_ifinfo_build_skb() already receives GFP flags as
    parameter.

Also, in ovs_vport_cmd_build_info(), let's change the GFP flags used
by nlmsg_new(). The function is allowed to sleep, so better make the
flags consistent with the ones used in the following
ovs_vport_cmd_fill_info() call.

Found by code inspection.

Fixes: 5ef2e8f61334 ("netns: notify netns id events")
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Acked-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Acked-by: Pravin B Shelar <pshelar@ovn.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index 4c2cd937869964301117bea84aeefd8174d641fd..c7e15a213ef2fe547b8dfc4c8e1638bd2b5b499b 100644 (file)
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -342,7 +342,7 @@ static inline struct net *read_pnet(const possible_net_t *pnet)
 #define __net_initconst        __initconst
 #endif
 
-int peernet2id_alloc(struct net *net, struct net *peer);
+int peernet2id_alloc(struct net *net, struct net *peer, gfp_t gfp);
 int peernet2id(struct net *net, struct net *peer);
 bool peernet_has_id(struct net *net, struct net *peer);
 struct net *get_net_ns_by_id(struct net *net, int id);

diff --git a/net/core/dev.c b/net/core/dev.c
index 1482e2ef2d25fc9cb83cafcb76c221fa93f59668..96afd464284a9d1a46a5a0409a0d1832de80d394 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -9770,7 +9770,7 @@ int dev_change_net_namespace(struct net_device *dev, struct net *net, const char
        call_netdevice_notifiers(NETDEV_UNREGISTER, dev);
        rcu_barrier();
 
-       new_nsid = peernet2id_alloc(dev_net(dev), net);
+       new_nsid = peernet2id_alloc(dev_net(dev), net, GFP_KERNEL);
        /* If there is an ifindex conflict assign a new one */
        if (__dev_get_by_index(net, dev->ifindex))
                new_ifindex = dev_new_index(net);

diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 5a4ae0845bac693af36b0904f2052d48be710365..39402840025e18682da44f40c509b265f9743fd1 100644 (file)
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -246,11 +246,11 @@ static int __peernet2id(struct net *net, struct net *peer)
 }
 
 static void rtnl_net_notifyid(struct net *net, int cmd, int id, u32 portid,
-                             struct nlmsghdr *nlh);
+                             struct nlmsghdr *nlh, gfp_t gfp);
 /* This function returns the id of a peer netns. If no id is assigned, one will
  * be allocated and returned.
  */
-int peernet2id_alloc(struct net *net, struct net *peer)
+int peernet2id_alloc(struct net *net, struct net *peer, gfp_t gfp)
 {
        bool alloc = false, alive = false;
        int id;
@@ -269,7 +269,7 @@ int peernet2id_alloc(struct net *net, struct net *peer)
        id = __peernet2id_alloc(net, peer, &alloc);
        spin_unlock_bh(&net->nsid_lock);
        if (alloc && id >= 0)
-               rtnl_net_notifyid(net, RTM_NEWNSID, id, 0, NULL);
+               rtnl_net_notifyid(net, RTM_NEWNSID, id, 0, NULL, gfp);
        if (alive)
                put_net(peer);
        return id;
@@ -534,7 +534,8 @@ static void unhash_nsid(struct net *net, struct net *last)
                        idr_remove(&tmp->netns_ids, id);
                spin_unlock_bh(&tmp->nsid_lock);
                if (id >= 0)
-                       rtnl_net_notifyid(tmp, RTM_DELNSID, id, 0, NULL);
+                       rtnl_net_notifyid(tmp, RTM_DELNSID, id, 0, NULL,
+                                         GFP_KERNEL);
                if (tmp == last)
                        break;
        }
@@ -767,7 +768,7 @@ static int rtnl_net_newid(struct sk_buff *skb, struct nlmsghdr *nlh,
        spin_unlock_bh(&net->nsid_lock);
        if (err >= 0) {
                rtnl_net_notifyid(net, RTM_NEWNSID, err, NETLINK_CB(skb).portid,
-                                 nlh);
+                                 nlh, GFP_KERNEL);
                err = 0;
        } else if (err == -ENOSPC && nsid >= 0) {
                err = -EEXIST;
@@ -1055,7 +1056,7 @@ end:
 }
 
 static void rtnl_net_notifyid(struct net *net, int cmd, int id, u32 portid,
-                             struct nlmsghdr *nlh)
+                             struct nlmsghdr *nlh, gfp_t gfp)
 {
        struct net_fill_args fillargs = {
                .portid = portid,
@@ -1066,7 +1067,7 @@ static void rtnl_net_notifyid(struct net *net, int cmd, int id, u32 portid,
        struct sk_buff *msg;
        int err = -ENOMEM;
 
-       msg = nlmsg_new(rtnl_net_get_size(), GFP_KERNEL);
+       msg = nlmsg_new(rtnl_net_get_size(), gfp);
        if (!msg)
                goto out;
 
@@ -1074,7 +1075,7 @@ static void rtnl_net_notifyid(struct net *net, int cmd, int id, u32 portid,
        if (err < 0)
                goto err_out;
 
-       rtnl_notify(msg, net, portid, RTNLGRP_NSID, nlh, 0);
+       rtnl_notify(msg, net, portid, RTNLGRP_NSID, nlh, gfp);
        return;
 
 err_out:

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 13493aae4e6cf0330a1a547c9164a1807991b5cc..ba4b4048ec3e55ebd90a75a9b0431ede4d6baeea 100644 (file)
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1523,7 +1523,7 @@ static noinline_for_stack int nla_put_ifalias(struct sk_buff *skb,
 
 static int rtnl_fill_link_netnsid(struct sk_buff *skb,
                                  const struct net_device *dev,
-                                 struct net *src_net)
+                                 struct net *src_net, gfp_t gfp)
 {
        bool put_iflink = false;
 
@@ -1531,7 +1531,7 @@ static int rtnl_fill_link_netnsid(struct sk_buff *skb,
                struct net *link_net = dev->rtnl_link_ops->get_link_net(dev);
 
                if (!net_eq(dev_net(dev), link_net)) {
-                       int id = peernet2id_alloc(src_net, link_net);
+                       int id = peernet2id_alloc(src_net, link_net, gfp);
 
                        if (nla_put_s32(skb, IFLA_LINK_NETNSID, id))
                                return -EMSGSIZE;
@@ -1589,7 +1589,7 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb,
                            int type, u32 pid, u32 seq, u32 change,
                            unsigned int flags, u32 ext_filter_mask,
                            u32 event, int *new_nsid, int new_ifindex,
-                           int tgt_netnsid)
+                           int tgt_netnsid, gfp_t gfp)
 {
        struct ifinfomsg *ifm;
        struct nlmsghdr *nlh;
@@ -1681,7 +1681,7 @@ static int rtnl_fill_ifinfo(struct sk_buff *skb,
                        goto nla_put_failure;
        }
 
-       if (rtnl_fill_link_netnsid(skb, dev, src_net))
+       if (rtnl_fill_link_netnsid(skb, dev, src_net, gfp))
                goto nla_put_failure;
 
        if (new_nsid &&
@@ -2001,7 +2001,7 @@ walk_entries:
                                               NETLINK_CB(cb->skb).portid,
                                               nlh->nlmsg_seq, 0, flags,
                                               ext_filter_mask, 0, NULL, 0,
-                                              netnsid);
+                                              netnsid, GFP_KERNEL);
 
                        if (err < 0) {
                                if (likely(skb->len))
@@ -3360,7 +3360,7 @@ static int rtnl_getlink(struct sk_buff *skb, struct nlmsghdr *nlh,
        err = rtnl_fill_ifinfo(nskb, dev, net,
                               RTM_NEWLINK, NETLINK_CB(skb).portid,
                               nlh->nlmsg_seq, 0, 0, ext_filter_mask,
-                              0, NULL, 0, netnsid);
+                              0, NULL, 0, netnsid, GFP_KERNEL);
        if (err < 0) {
                /* -EMSGSIZE implies BUG in if_nlmsg_size */
                WARN_ON(err == -EMSGSIZE);
@@ -3472,7 +3472,7 @@ struct sk_buff *rtmsg_ifinfo_build_skb(int type, struct net_device *dev,
 
        err = rtnl_fill_ifinfo(skb, dev, dev_net(dev),
                               type, 0, 0, change, 0, 0, event,
-                              new_nsid, new_ifindex, -1);
+                              new_nsid, new_ifindex, -1, flags);
        if (err < 0) {
                /* -EMSGSIZE implies BUG in if_nlmsg_size() */
                WARN_ON(err == -EMSGSIZE);

diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index f30e406fbec5a321de0a489b2d41c39dd08fb561..d8c364d637b12d8ec6f1e30bb46a06b27cd06311 100644 (file)
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -1881,7 +1881,7 @@ static struct genl_family dp_datapath_genl_family __ro_after_init = {
 /* Called with ovs_mutex or RCU read lock. */
 static int ovs_vport_cmd_fill_info(struct vport *vport, struct sk_buff *skb,
                                   struct net *net, u32 portid, u32 seq,
-                                  u32 flags, u8 cmd)
+                                  u32 flags, u8 cmd, gfp_t gfp)
 {
        struct ovs_header *ovs_header;
        struct ovs_vport_stats vport_stats;
@@ -1902,7 +1902,7 @@ static int ovs_vport_cmd_fill_info(struct vport *vport, struct sk_buff *skb,
                goto nla_put_failure;
 
        if (!net_eq(net, dev_net(vport->dev))) {
-               int id = peernet2id_alloc(net, dev_net(vport->dev));
+               int id = peernet2id_alloc(net, dev_net(vport->dev), gfp);
 
                if (nla_put_s32(skb, OVS_VPORT_ATTR_NETNSID, id))
                        goto nla_put_failure;
@@ -1943,11 +1943,12 @@ struct sk_buff *ovs_vport_cmd_build_info(struct vport *vport, struct net *net,
        struct sk_buff *skb;
        int retval;
 
-       skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);
+       skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
        if (!skb)
                return ERR_PTR(-ENOMEM);
 
-       retval = ovs_vport_cmd_fill_info(vport, skb, net, portid, seq, 0, cmd);
+       retval = ovs_vport_cmd_fill_info(vport, skb, net, portid, seq, 0, cmd,
+                                        GFP_KERNEL);
        BUG_ON(retval < 0);
 
        return skb;
@@ -2089,7 +2090,7 @@ restart:
 
        err = ovs_vport_cmd_fill_info(vport, reply, genl_info_net(info),
                                      info->snd_portid, info->snd_seq, 0,
-                                     OVS_VPORT_CMD_NEW);
+                                     OVS_VPORT_CMD_NEW, GFP_KERNEL);
 
        new_headroom = netdev_get_fwd_headroom(vport->dev);
 
@@ -2150,7 +2151,7 @@ static int ovs_vport_cmd_set(struct sk_buff *skb, struct genl_info *info)
 
        err = ovs_vport_cmd_fill_info(vport, reply, genl_info_net(info),
                                      info->snd_portid, info->snd_seq, 0,
-                                     OVS_VPORT_CMD_SET);
+                                     OVS_VPORT_CMD_SET, GFP_KERNEL);
        BUG_ON(err < 0);
 
        ovs_unlock();
@@ -2190,7 +2191,7 @@ static int ovs_vport_cmd_del(struct sk_buff *skb, struct genl_info *info)
 
        err = ovs_vport_cmd_fill_info(vport, reply, genl_info_net(info),
                                      info->snd_portid, info->snd_seq, 0,
-                                     OVS_VPORT_CMD_DEL);
+                                     OVS_VPORT_CMD_DEL, GFP_KERNEL);
        BUG_ON(err < 0);
 
        /* the vport deletion may trigger dp headroom update */
@@ -2237,7 +2238,7 @@ static int ovs_vport_cmd_get(struct sk_buff *skb, struct genl_info *info)
                goto exit_unlock_free;
        err = ovs_vport_cmd_fill_info(vport, reply, genl_info_net(info),
                                      info->snd_portid, info->snd_seq, 0,
-                                     OVS_VPORT_CMD_GET);
+                                     OVS_VPORT_CMD_GET, GFP_ATOMIC);
        BUG_ON(err < 0);
        rcu_read_unlock();
 
@@ -2273,7 +2274,8 @@ static int ovs_vport_cmd_dump(struct sk_buff *skb, struct netlink_callback *cb)
                                                    NETLINK_CB(cb->skb).portid,
                                                    cb->nlh->nlmsg_seq,
                                                    NLM_F_MULTI,
-                                                   OVS_VPORT_CMD_GET) < 0)
+                                                   OVS_VPORT_CMD_GET,
+                                                   GFP_ATOMIC) < 0)
                                goto out;
 
                        j++;