From: Matteo Croce <mcroce@redhat.com>
Date: Mon, 1 Jul 2019 19:01:55 +0200
Subject: ipv4: don't set IPv6 only flags to IPv4 addresses
Git-commit: 2e60546368165c2449564d71f6005dda9205b5fb
Patch-mainline: 5.3-rc1
References: networking-stable-19_07_25
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>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
net/ipv4/devinet.c | 8 ++++++++
1 file changed, 8 insertions(+)
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -66,6 +66,11 @@
#include <net/net_namespace.h>
#include <net/addrconf.h>
+#define IPV6ONLY_FLAGS \
+ (IFA_F_NODAD | IFA_F_OPTIMISTIC | IFA_F_DADFAILED | \
+ IFA_F_HOMEADDRESS | IFA_F_TENTATIVE | \
+ IFA_F_MANAGETEMPADDR | IFA_F_STABLE_PRIVACY)
+
static struct ipv4_devconf ipv4_devconf = {
.data = {
[IPV4_DEVCONF_ACCEPT_REDIRECTS - 1] = 1,
@@ -452,6 +457,9 @@ static int __inet_insert_ifa(struct in_i
ifa->ifa_flags &= ~IFA_F_SECONDARY;
last_primary = &in_dev->ifa_list;
+ /* Don't set IPv6 only flags to IPv4 addresses */
+ ifa->ifa_flags &= ~IPV6ONLY_FLAGS;
+
for (ifap = &in_dev->ifa_list; (ifa1 = *ifap) != NULL;
ifap = &ifa1->ifa_next) {
if (!(ifa1->ifa_flags & IFA_F_SECONDARY) &&