netdev - [PATCH net-next, v2] netlink: correct nlmsg size for multicast notifications

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Message-ID: <20241221100007.1910089-1-yuyanghuang@google.com>
Date: Sat, 21 Dec 2024 19:00:07 +0900
From: Yuyang Huang <yuyanghuang@...gle.com>
To: Yuyang Huang <yuyanghuang@...gle.com>
Cc: "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>, 
	David Ahern <dsahern@...nel.org>, roopa@...ulusnetworks.com, jiri@...nulli.us, 
	stephen@...workplumber.org, jimictw@...gle.com, prohr@...gle.com, 
	liuhangbin@...il.com, nicolas.dichtel@...nd.com, andrew@...n.ch, 
	pruddy@...tta.att-mail.com, netdev@...r.kernel.org, 
	"Maciej Żenczykowski" <maze@...gle.com>, Lorenzo Colitti <lorenzo@...gle.com>
Subject: [PATCH net-next, v2] netlink: correct nlmsg size for multicast notifications

Corrected the netlink message size calculation for multicast group
join/leave notifications. The previous calculation did not account for
the inclusion of both IPv4/IPv6 addresses and ifa_cacheinfo in the
payload. This fix ensures that the allocated message size is
sufficient to hold all necessary information.

This patch also includes the following improvements:
* Uses GFP_KERNEL instead of GFP_ATOMIC when holding the RTNL mutex.
* Uses nla_total_size(sizeof(struct in6_addr)) instead of
  nla_total_size(16).
* Removes unnecessary EXPORT_SYMBOL().

Fixes: 2c2b61d2138f ("netlink: add IGMP/MLD join/leave notifications")
Cc: Maciej Żenczykowski <maze@...gle.com>
Cc: Lorenzo Colitti <lorenzo@...gle.com>
Signed-off-by: Yuyang Huang <yuyanghuang@...gle.com>
---

Changelog since v1:
- Uses GFP_KERNEL instead of GFP_ATOMIC when holding the RTNL mutex.
- Uses nla_total_size(sizeof(struct in6_addr)) instead of
  nla_total_size(16).
- Removes unnecessary EXPORT_SYMBOL().

 net/ipv4/igmp.c     | 6 ++++--
 net/ipv6/addrconf.c | 1 -
 net/ipv6/mcast.c    | 6 ++++--
 3 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index 8a370ef37d3f..3da126cea884 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -1473,7 +1473,9 @@ static void inet_ifmcaddr_notify(struct net_device *dev,
 	int err = -ENOMEM;
 
 	skb = nlmsg_new(NLMSG_ALIGN(sizeof(struct ifaddrmsg)) +
-			nla_total_size(sizeof(__be32)), GFP_ATOMIC);
+			nla_total_size(sizeof(__be32)) +
+			nla_total_size(sizeof(struct ifa_cacheinfo)),
+			GFP_KERNEL);
 	if (!skb)
 		goto error;
 
@@ -1484,7 +1486,7 @@ static void inet_ifmcaddr_notify(struct net_device *dev,
 		goto error;
 	}
 
-	rtnl_notify(skb, net, 0, RTNLGRP_IPV4_MCADDR, NULL, GFP_ATOMIC);
+	rtnl_notify(skb, net, 0, RTNLGRP_IPV4_MCADDR, NULL, GFP_KERNEL);
 	return;
 error:
 	rtnl_set_sk_err(net, RTNLGRP_IPV4_MCADDR, err);
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 2e2684886953..4da409bc4577 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -5239,7 +5239,6 @@ int inet6_fill_ifmcaddr(struct sk_buff *skb,
 	nlmsg_end(skb, nlh);
 	return 0;
 }
-EXPORT_SYMBOL(inet6_fill_ifmcaddr);
 
 static int inet6_fill_ifacaddr(struct sk_buff *skb,
 			       const struct ifacaddr6 *ifaca,
diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index 587831c148de..9dfdb40988b0 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -920,7 +920,9 @@ static void inet6_ifmcaddr_notify(struct net_device *dev,
 	int err = -ENOMEM;
 
 	skb = nlmsg_new(NLMSG_ALIGN(sizeof(struct ifaddrmsg)) +
-			nla_total_size(16), GFP_ATOMIC);
+			nla_total_size(sizeof(struct in6_addr)) +
+			nla_total_size(sizeof(struct ifa_cacheinfo)),
+			GFP_KERNEL);
 	if (!skb)
 		goto error;
 
@@ -931,7 +933,7 @@ static void inet6_ifmcaddr_notify(struct net_device *dev,
 		goto error;
 	}
 
-	rtnl_notify(skb, net, 0, RTNLGRP_IPV6_MCADDR, NULL, GFP_ATOMIC);
+	rtnl_notify(skb, net, 0, RTNLGRP_IPV6_MCADDR, NULL, GFP_KERNEL);
 	return;
 error:
 	rtnl_set_sk_err(net, RTNLGRP_IPV6_MCADDR, err);
-- 
2.47.1.613.gc27f4b7a9f-goog