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netns: fix GFP flags in rtnl_net_notifyid()

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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: 9a9634545c ("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>
This commit is contained in:
Guillaume Nault
2019-10-23 18:39:04 +02:00
committed by David S. Miller
parent 16d6528792
commit d4e4fdf9e4
5 changed files with 29 additions and 26 deletions
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20
net/openvswitch/datapath.c
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@@ -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++;