Two cases of overlapping changes, nothing fancy.

Signed-off-by: David S. Miller <davem@davemloft.net>

Avoid the situation where an IPV6 only flag is applied to an IPv4 address:

    # ip addr add 192.0.2.1/24 dev dummy0 nodad home mngtmpaddr noprefixroute
    # ip -4 addr show dev dummy0
    2: dummy0: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
        inet 192.0.2.1/24 scope global noprefixroute dummy0
           valid_lft forever preferred_lft forever

Or worse, by sending a malicious netlink command:

    # ip -4 addr show dev dummy0
    2: dummy0: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
        inet 192.0.2.1/24 scope global nodad optimistic dadfailed home tentative mngtmpaddr noprefixroute stable-privacy dummy0
           valid_lft forever preferred_lft forever

Signed-off-by: Matteo Croce <mcroce@redhat.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

secondary address promotion causes infinite loop -- it arranges
for ifa->ifa_next to point back to itself.

Problem is that 'prev_prom' and 'last_prim' might point at the same entry,
so 'last_sec' pointer must be obtained after prev_prom->next update.

Fixes: 2638eb8b50cf ("net: ipv4: provide __rcu annotation for ifa_list")
Reported-by: Ran Rozenstein <ranro@mellanox.com>
Reported-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

When arp_ignore=3, the NIC won't reply for scope host addresses, but
if enable route_locanet, we need to reply ip address with head 127 and
scope RT_SCOPE_HOST.

Fixes: d0daebc3d622 ("ipv4: Add interface option to enable routing of 127.0.0.0/8")

Signed-off-by: Shijie Luo <luoshijie1@huawei.com>
Signed-off-by: Zhiqiang Liu <liuzhiqiang26@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Suppose we have two interfaces eth0 and eth1 in two hosts, follow
the same steps in the two hosts:
 # sysctl -w net.ipv4.conf.eth1.route_localnet=1
 # sysctl -w net.ipv4.conf.eth1.arp_announce=2
 # ip route del 127.0.0.0/8 dev lo table local
and then set ip to eth1 in host1 like:
 # ifconfig eth1 127.25.3.4/24
set ip to eth2 in host2 and ping host1:
 # ifconfig eth1 127.25.3.14/24
 # ping -I eth1 127.25.3.4
Well, host2 cannot connect to host1.

When set a ip address with head 127, the scope of the address defaults
to RT_SCOPE_HOST. In this situation, host2 will use arp_solicit() to
send a arp request for the mac address of host1 with ip
address 127.25.3.14. When arp_announce=2, inet_select_addr() cannot
select a correct saddr with condition ifa->ifa_scope > scope, because
ifa_scope is RT_SCOPE_HOST and scope is RT_SCOPE_LINK. Then,
inet_select_addr() will go to no_in_dev to lookup all interfaces to find
a primary ip and finally get the primary ip of eth0.

Here I add a localnet_scope defaults to RT_SCOPE_HOST, and when
route_localnet is enabled, this value changes to RT_SCOPE_LINK to make
inet_select_addr() find a correct primary ip as saddr of arp request.

Fixes: d0daebc3d622 ("ipv4: Add interface option to enable routing of 127.0.0.0/8")

Signed-off-by: Shijie Luo <luoshijie1@huawei.com>
Signed-off-by: Zhiqiang Liu <liuzhiqiang26@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Causes crash when lifetime expires on an adress as garbage is
dereferenced soon after.

This used to look like this:

 for (ifap = &ifa->ifa_dev->ifa_list;
      *ifap != NULL; ifap = &(*ifap)->ifa_next) {
          if (*ifap == ifa) ...

but this was changed to:

struct in_ifaddr *tmp;

ifap = &ifa->ifa_dev->ifa_list;
tmp = rtnl_dereference(*ifap);
while (tmp) {
   tmp = rtnl_dereference(tmp->ifa_next); // Bogus
   if (rtnl_dereference(*ifap) == ifa) {
     ...
   ifap = &tmp->ifa_next;		// Can be NULL
   tmp = rtnl_dereference(*ifap);	// Dereference
   }
}

Remove the bogus assigment/list entry skip.

Fixes: 2638eb8b50cf ("net: ipv4: provide __rcu annotation for ifa_list")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

Some ISDN files that got removed in net-next had some changes
done in mainline, take the removals.

Signed-off-by: David S. Miller <davem@davemloft.net>

syzbot triggered following splat when strict netlink
validation is enabled:

net/ipv4/devinet.c:1766 suspicious rcu_dereference_check() usage!

This occurs because we hold RTNL mutex, but no rcu read lock.
The second call site holds both, so just switch to the _rtnl variant.

Reported-by: syzbot+bad6e32808a3a97b1515@syzkaller.appspotmail.com
Fixes: 2638eb8b50cf ("net: ipv4: provide __rcu annotation for ifa_list")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

ifa_list is protected by rcu, yet code doesn't reflect this.

Add the __rcu annotations and fix up all places that are now reported by
sparse.

I've done this in the same commit to not add intermediate patches that
result in new warnings.

Reported-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

This also replaces spots that used for_primary_ifa().

for_primary_ifa() aborts the loop on the first secondary address seen.

Replace it with either the rcu or rtnl variant of in_dev_for_each_ifa(),
but two places will now also consider secondary addresses too:
inet_addr_onlink() and inet_ifa_byprefix().

I do not understand why they should ignore secondary addresses.

Why would a secondary address not be considered 'on link'?
When matching a prefix, why ignore a matching secondary address?

Other places get converted as well, but gain "->flags & SECONDARY" check.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>