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Subject[PATCH 4.19 48/79] netns: fix GFP flags in rtnl_net_notifyid()
Date
From: Guillaume Nault <gnault@redhat.com>

[ Upstream commit d4e4fdf9e4a27c87edb79b1478955075be141f67 ]

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: 9a9634545c70 ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/net/net_namespace.h | 2 +-
net/core/dev.c | 2 +-
net/core/net_namespace.c | 17 +++++++++--------
net/core/rtnetlink.c | 14 +++++++-------
net/openvswitch/datapath.c | 20 +++++++++++---------
5 files changed, 29 insertions(+), 26 deletions(-)

--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -322,7 +322,7 @@ static inline struct net *read_pnet(cons
#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);
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -9211,7 +9211,7 @@ int dev_change_net_namespace(struct net_
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);
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -226,11 +226,11 @@ static int __peernet2id(struct net *net,
return __peernet2id_alloc(net, peer, &no);
}

-static void rtnl_net_notifyid(struct net *net, int cmd, int id);
+static void rtnl_net_notifyid(struct net *net, int cmd, int id, 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;
@@ -249,7 +249,7 @@ int peernet2id_alloc(struct net *net, st
id = __peernet2id_alloc(net, peer, &alloc);
spin_unlock_bh(&net->nsid_lock);
if (alloc && id >= 0)
- rtnl_net_notifyid(net, RTM_NEWNSID, id);
+ rtnl_net_notifyid(net, RTM_NEWNSID, id, gfp);
if (alive)
put_net(peer);
return id;
@@ -495,7 +495,8 @@ static void unhash_nsid(struct net *net,
idr_remove(&tmp->netns_ids, id);
spin_unlock_bh(&tmp->nsid_lock);
if (id >= 0)
- rtnl_net_notifyid(tmp, RTM_DELNSID, id);
+ rtnl_net_notifyid(tmp, RTM_DELNSID, id,
+ GFP_KERNEL);
if (tmp == last)
break;
}
@@ -720,7 +721,7 @@ static int rtnl_net_newid(struct sk_buff
err = alloc_netid(net, peer, nsid);
spin_unlock_bh(&net->nsid_lock);
if (err >= 0) {
- rtnl_net_notifyid(net, RTM_NEWNSID, err);
+ rtnl_net_notifyid(net, RTM_NEWNSID, err, GFP_KERNEL);
err = 0;
} else if (err == -ENOSPC && nsid >= 0) {
err = -EEXIST;
@@ -862,12 +863,12 @@ static int rtnl_net_dumpid(struct sk_buf
return skb->len;
}

-static void rtnl_net_notifyid(struct net *net, int cmd, int id)
+static void rtnl_net_notifyid(struct net *net, int cmd, int id, gfp_t gfp)
{
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;

@@ -875,7 +876,7 @@ static void rtnl_net_notifyid(struct net
if (err < 0)
goto err_out;

- rtnl_notify(msg, net, 0, RTNLGRP_NSID, NULL, 0);
+ rtnl_notify(msg, net, 0, RTNLGRP_NSID, NULL, gfp);
return;

err_out:
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1519,7 +1519,7 @@ static noinline_for_stack int nla_put_if

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;

@@ -1527,7 +1527,7 @@ static int rtnl_fill_link_netnsid(struct
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;
@@ -1585,7 +1585,7 @@ static int rtnl_fill_ifinfo(struct sk_bu
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;
@@ -1677,7 +1677,7 @@ static int rtnl_fill_ifinfo(struct sk_bu
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 &&
@@ -1933,7 +1933,7 @@ static int rtnl_dump_ifinfo(struct sk_bu
cb->nlh->nlmsg_seq, 0,
flags,
ext_filter_mask, 0, NULL, 0,
- netnsid);
+ netnsid, GFP_KERNEL);

if (err < 0) {
if (likely(skb->len))
@@ -3215,7 +3215,7 @@ static int rtnl_getlink(struct sk_buff *
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);
@@ -3325,7 +3325,7 @@ struct sk_buff *rtmsg_ifinfo_build_skb(i

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);
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -1843,7 +1843,7 @@ static struct genl_family dp_datapath_ge
/* 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;
@@ -1864,7 +1864,7 @@ static int ovs_vport_cmd_fill_info(struc
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;
@@ -1905,11 +1905,12 @@ struct sk_buff *ovs_vport_cmd_build_info
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;
@@ -2042,7 +2043,7 @@ 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);

if (netdev_get_fwd_headroom(vport->dev) > dp->max_headroom)
update_headroom(dp);
@@ -2101,7 +2102,7 @@ static int ovs_vport_cmd_set(struct sk_b

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_ATOMIC);
BUG_ON(err < 0);

ovs_unlock();
@@ -2140,7 +2141,7 @@ static int ovs_vport_cmd_del(struct sk_b

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 */
@@ -2182,7 +2183,7 @@ static int ovs_vport_cmd_get(struct sk_b
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_NEW);
+ OVS_VPORT_CMD_NEW, GFP_ATOMIC);
BUG_ON(err < 0);
rcu_read_unlock();

@@ -2218,7 +2219,8 @@ static int ovs_vport_cmd_dump(struct sk_
NETLINK_CB(cb->skb).portid,
cb->nlh->nlmsg_seq,
NLM_F_MULTI,
- OVS_VPORT_CMD_NEW) < 0)
+ OVS_VPORT_CMD_NEW,
+ GFP_ATOMIC) < 0)
goto out;

j++;

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