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author | Shijie Luo <luoshijie1@huawei.com> | 2019-06-18 18:14:03 +0300 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2019-06-24 19:01:42 +0300 |
commit | d8c444d540beaa39aff834c5b83df7e86a1ae765 (patch) | |
tree | d5f024393ace14a232f1d139215614f7a941569a /net | |
parent | 8bc81c570831f5b739a1c8dfe547b828ef398dfb (diff) | |
download | linux-d8c444d540beaa39aff834c5b83df7e86a1ae765.tar.xz |
ipv4: fix inet_select_addr() when enable route_localnet
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>
Diffstat (limited to 'net')
-rw-r--r-- | net/ipv4/devinet.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c index 914ccc7f192a..6fd4628d10b9 100644 --- a/net/ipv4/devinet.c +++ b/net/ipv4/devinet.c @@ -1287,6 +1287,7 @@ __be32 inet_select_addr(const struct net_device *dev, __be32 dst, int scope) { const struct in_ifaddr *ifa; __be32 addr = 0; + unsigned char localnet_scope = RT_SCOPE_HOST; struct in_device *in_dev; struct net *net = dev_net(dev); int master_idx; @@ -1296,10 +1297,13 @@ __be32 inet_select_addr(const struct net_device *dev, __be32 dst, int scope) if (!in_dev) goto no_in_dev; + if (unlikely(IN_DEV_ROUTE_LOCALNET(in_dev))) + localnet_scope = RT_SCOPE_LINK; + in_dev_for_each_ifa_rcu(ifa, in_dev) { if (ifa->ifa_flags & IFA_F_SECONDARY) continue; - if (ifa->ifa_scope > scope) + if (min(ifa->ifa_scope, localnet_scope) > scope) continue; if (!dst || inet_ifa_match(dst, ifa)) { addr = ifa->ifa_local; |