ipv4: Set ifa->ifa_dev in inet_alloc_ifa().

When a new IPv4 address is assigned via ioctl(SIOCSIFADDR),
inet_set_ifa() sets ifa->ifa_dev if it's different from in_dev
passed as an argument.

In this case, ifa is always a newly allocated object, and
ifa->ifa_dev is NULL.

inet_set_ifa() can be called for an existing reused ifa, then,
this check is always false.

Let's set ifa_dev in inet_alloc_ifa() and remove the check
in inet_set_ifa().

Now, inet_alloc_ifa() is symmetric with inet_rcu_free_ifa().

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20240809235406.50187-3-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index ddab1511645425a3a6ee2da1e22f15457b534171..9f4add07e67d7bb576981146598b553e5cb8606c 100644 (file)
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -216,9 +216,18 @@ static void devinet_sysctl_unregister(struct in_device *idev)
 
 /* Locks all the inet devices. */
 
-static struct in_ifaddr *inet_alloc_ifa(void)
+static struct in_ifaddr *inet_alloc_ifa(struct in_device *in_dev)
 {
-       return kzalloc(sizeof(struct in_ifaddr), GFP_KERNEL_ACCOUNT);
+       struct in_ifaddr *ifa;
+
+       ifa = kzalloc(sizeof(*ifa), GFP_KERNEL_ACCOUNT);
+       if (!ifa)
+               return NULL;
+
+       in_dev_hold(in_dev);
+       ifa->ifa_dev = in_dev;
+
+       return ifa;
 }
 
 static void inet_rcu_free_ifa(struct rcu_head *head)
@@ -576,11 +585,7 @@ static int inet_set_ifa(struct net_device *dev, struct in_ifaddr *ifa)
 
        ipv4_devconf_setall(in_dev);
        neigh_parms_data_state_setall(in_dev->arp_parms);
-       if (ifa->ifa_dev != in_dev) {
-               WARN_ON(ifa->ifa_dev);
-               in_dev_hold(in_dev);
-               ifa->ifa_dev = in_dev;
-       }
+
        if (ipv4_is_loopback(ifa->ifa_local))
                ifa->ifa_scope = RT_SCOPE_HOST;
        return inet_insert_ifa(ifa);
@@ -871,7 +876,7 @@ static struct in_ifaddr *rtm_to_ifaddr(struct net *net, struct nlmsghdr *nlh,
        if (!in_dev)
                goto errout;
 
-       ifa = inet_alloc_ifa();
+       ifa = inet_alloc_ifa(in_dev);
        if (!ifa)
                /*
                 * A potential indev allocation can be left alive, it stays
@@ -881,7 +886,6 @@ static struct in_ifaddr *rtm_to_ifaddr(struct net *net, struct nlmsghdr *nlh,
 
        ipv4_devconf_setall(in_dev);
        neigh_parms_data_state_setall(in_dev->arp_parms);
-       in_dev_hold(in_dev);
 
        if (!tb[IFA_ADDRESS])
                tb[IFA_ADDRESS] = tb[IFA_LOCAL];
@@ -892,8 +896,6 @@ static struct in_ifaddr *rtm_to_ifaddr(struct net *net, struct nlmsghdr *nlh,
        ifa->ifa_flags = tb[IFA_FLAGS] ? nla_get_u32(tb[IFA_FLAGS]) :
                                         ifm->ifa_flags;
        ifa->ifa_scope = ifm->ifa_scope;
-       ifa->ifa_dev = in_dev;
-
        ifa->ifa_local = nla_get_in_addr(tb[IFA_LOCAL]);
        ifa->ifa_address = nla_get_in_addr(tb[IFA_ADDRESS]);
 
@@ -1182,7 +1184,7 @@ int devinet_ioctl(struct net *net, unsigned int cmd, struct ifreq *ifr)
                        ret = -ENOBUFS;
                        if (!in_dev)
                                break;
-                       ifa = inet_alloc_ifa();
+                       ifa = inet_alloc_ifa(in_dev);
                        if (!ifa)
                                break;
                        INIT_HLIST_NODE(&ifa->hash);
@@ -1584,7 +1586,7 @@ static int inetdev_event(struct notifier_block *this, unsigned long event,
                if (!inetdev_valid_mtu(dev->mtu))
                        break;
                if (dev->flags & IFF_LOOPBACK) {
-                       struct in_ifaddr *ifa = inet_alloc_ifa();
+                       struct in_ifaddr *ifa = inet_alloc_ifa(in_dev);
 
                        if (ifa) {
                                INIT_HLIST_NODE(&ifa->hash);
@@ -1592,8 +1594,6 @@ static int inetdev_event(struct notifier_block *this, unsigned long event,
                                  ifa->ifa_address = htonl(INADDR_LOOPBACK);
                                ifa->ifa_prefixlen = 8;
                                ifa->ifa_mask = inet_make_mask(8);
-                               in_dev_hold(in_dev);
-                               ifa->ifa_dev = in_dev;
                                ifa->ifa_scope = RT_SCOPE_HOST;
                                memcpy(ifa->ifa_label, dev->name, IFNAMSIZ);
                                set_ifa_lifetime(ifa, INFINITY_LIFE_TIME,