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Message-ID: <20240425170002.68160-6-kuniyu@amazon.com>
Date: Thu, 25 Apr 2024 10:00:01 -0700
From: Kuniyuki Iwashima <kuniyu@...zon.com>
To: "David S. Miller" <davem@...emloft.net>, David Ahern <dsahern@...nel.org>,
Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, "Paolo
Abeni" <pabeni@...hat.com>
CC: Kuniyuki Iwashima <kuniyu@...zon.com>, Kuniyuki Iwashima
<kuni1840@...il.com>, <netdev@...r.kernel.org>
Subject: [PATCH v2 net-next 5/6] arp: Get dev after calling arp_req_(delete|set|get)().
arp_ioctl() holds rtnl_lock() first regardless of cmd (SIOCDARP,
SIOCSARP, and SIOCGARP) to get net_device by __dev_get_by_name().
In the SIOCGARP path, arp_req_get() calls neigh_lookup(), which
looks up a neighbour entry under RCU.
We will extend the RCU section not to take rtnl_lock() and instead
use dev_get_by_name_rcu() for SIOCGARP.
As a preparation, let's move __dev_get_by_name() into another
function and call it from arp_req_delete(), arp_req_set(), and
arp_req_get().
Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com>
---
net/ipv4/arp.c | 86 +++++++++++++++++++++++++++++---------------------
1 file changed, 50 insertions(+), 36 deletions(-)
diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
index 60f633b24ec8..5034920be85a 100644
--- a/net/ipv4/arp.c
+++ b/net/ipv4/arp.c
@@ -1003,12 +1003,36 @@ static int arp_rcv(struct sk_buff *skb, struct net_device *dev,
* User level interface (ioctl)
*/
+static struct net_device *arp_req_dev_by_name(struct net *net, struct arpreq *r)
+{
+ struct net_device *dev;
+
+ dev = __dev_get_by_name(net, r->arp_dev);
+ if (!dev)
+ return ERR_PTR(-ENODEV);
+
+ /* Mmmm... It is wrong... ARPHRD_NETROM == 0 */
+ if (!r->arp_ha.sa_family)
+ r->arp_ha.sa_family = dev->type;
+
+ if ((r->arp_flags & ATF_COM) && r->arp_ha.sa_family != dev->type)
+ return ERR_PTR(-EINVAL);
+
+ return dev;
+}
+
static struct net_device *arp_req_dev(struct net *net, struct arpreq *r)
{
struct net_device *dev;
struct rtable *rt;
__be32 ip;
+ if (r->arp_dev[0])
+ return arp_req_dev_by_name(net, r);
+
+ if (r->arp_flags & ATF_PUBL)
+ return NULL;
+
ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
rt = ip_route_output(net, ip, 0, 0, 0, RT_SCOPE_LINK);
@@ -1063,21 +1087,20 @@ static int arp_req_set_public(struct net *net, struct arpreq *r,
return arp_req_set_proxy(net, dev, 1);
}
-static int arp_req_set(struct net *net, struct arpreq *r,
- struct net_device *dev)
+static int arp_req_set(struct net *net, struct arpreq *r)
{
struct neighbour *neigh;
+ struct net_device *dev;
__be32 ip;
int err;
+ dev = arp_req_dev(net, r);
+ if (IS_ERR(dev))
+ return PTR_ERR(dev);
+
if (r->arp_flags & ATF_PUBL)
return arp_req_set_public(net, r, dev);
- if (!dev) {
- dev = arp_req_dev(net, r);
- if (IS_ERR(dev))
- return PTR_ERR(dev);
- }
switch (dev->type) {
#if IS_ENABLED(CONFIG_FDDI)
case ARPHRD_FDDI:
@@ -1134,10 +1157,18 @@ static unsigned int arp_state_to_flags(struct neighbour *neigh)
* Get an ARP cache entry.
*/
-static int arp_req_get(struct arpreq *r, struct net_device *dev)
+static int arp_req_get(struct net *net, struct arpreq *r)
{
__be32 ip = ((struct sockaddr_in *) &r->arp_pa)->sin_addr.s_addr;
struct neighbour *neigh;
+ struct net_device *dev;
+
+ if (!r->arp_dev[0])
+ return -ENODEV;
+
+ dev = arp_req_dev_by_name(net, r);
+ if (IS_ERR(dev))
+ return PTR_ERR(dev);
neigh = neigh_lookup(&arp_tbl, &ip, dev);
if (!neigh)
@@ -1201,20 +1232,20 @@ static int arp_req_delete_public(struct net *net, struct arpreq *r,
return arp_req_set_proxy(net, dev, 0);
}
-static int arp_req_delete(struct net *net, struct arpreq *r,
- struct net_device *dev)
+static int arp_req_delete(struct net *net, struct arpreq *r)
{
+ struct net_device *dev;
__be32 ip;
+ dev = arp_req_dev(net, r);
+ if (IS_ERR(dev))
+ return PTR_ERR(dev);
+
if (r->arp_flags & ATF_PUBL)
return arp_req_delete_public(net, r, dev);
ip = ((struct sockaddr_in *)&r->arp_pa)->sin_addr.s_addr;
- if (!dev) {
- dev = arp_req_dev(net, r);
- if (IS_ERR(dev))
- return PTR_ERR(dev);
- }
+
return arp_invalidate(dev, ip, true);
}
@@ -1224,7 +1255,6 @@ static int arp_req_delete(struct net *net, struct arpreq *r,
int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg)
{
- struct net_device *dev = NULL;
struct arpreq r;
__be32 *netmask;
int err;
@@ -1258,35 +1288,19 @@ int arp_ioctl(struct net *net, unsigned int cmd, void __user *arg)
return -EINVAL;
rtnl_lock();
- if (r.arp_dev[0]) {
- err = -ENODEV;
- dev = __dev_get_by_name(net, r.arp_dev);
- if (!dev)
- goto out;
-
- /* Mmmm... It is wrong... ARPHRD_NETROM==0 */
- if (!r.arp_ha.sa_family)
- r.arp_ha.sa_family = dev->type;
- err = -EINVAL;
- if ((r.arp_flags & ATF_COM) && r.arp_ha.sa_family != dev->type)
- goto out;
- } else if (cmd == SIOCGARP) {
- err = -ENODEV;
- goto out;
- }
switch (cmd) {
case SIOCDARP:
- err = arp_req_delete(net, &r, dev);
+ err = arp_req_delete(net, &r);
break;
case SIOCSARP:
- err = arp_req_set(net, &r, dev);
+ err = arp_req_set(net, &r);
break;
case SIOCGARP:
- err = arp_req_get(&r, dev);
+ err = arp_req_get(net, &r);
break;
}
-out:
+
rtnl_unlock();
if (cmd == SIOCGARP && !err && copy_to_user(arg, &r, sizeof(r)))
err = -EFAULT;
--
2.30.2
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