ip6_tunnel: allow to change mode for the ip6tnl0
The fallback device is in ipv6 mode by default.
The mode can not be changed in runtime, so there
is no way to decapsulate ip4in6 packets coming from
various sources without creating the specific tunnel
ifaces for each peer.
This allows to update the fallback tunnel device, but only
the mode could be changed. Usual command should work for the
fallback device: `ip -6 tun change ip6tnl0 mode any`
The fallback device can not be hidden from the packet receiver
as a regular tunnel, but there is no need for synchronization
as long as we do single assignment.
Cc: David S. Miller <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: Alexey Andriyanov <alan@al-an.info>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index 9409887..8c97cd1 100644
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -477,6 +477,7 @@
int rel_msg = 0;
u8 rel_type = ICMPV6_DEST_UNREACH;
u8 rel_code = ICMPV6_ADDR_UNREACH;
+ u8 tproto;
__u32 rel_info = 0;
__u16 len;
int err = -ENOENT;
@@ -490,7 +491,8 @@
&ipv6h->saddr)) == NULL)
goto out;
- if (t->parms.proto != ipproto && t->parms.proto != 0)
+ tproto = ACCESS_ONCE(t->parms.proto);
+ if (tproto != ipproto && tproto != 0)
goto out;
err = 0;
@@ -791,6 +793,7 @@
{
struct ip6_tnl *t;
const struct ipv6hdr *ipv6h = ipv6_hdr(skb);
+ u8 tproto;
int err;
rcu_read_lock();
@@ -799,7 +802,8 @@
&ipv6h->daddr)) != NULL) {
struct pcpu_sw_netstats *tstats;
- if (t->parms.proto != ipproto && t->parms.proto != 0) {
+ tproto = ACCESS_ONCE(t->parms.proto);
+ if (tproto != ipproto && tproto != 0) {
rcu_read_unlock();
goto discard;
}
@@ -1078,9 +1082,11 @@
struct flowi6 fl6;
__u8 dsfield;
__u32 mtu;
+ u8 tproto;
int err;
- if ((t->parms.proto != IPPROTO_IPIP && t->parms.proto != 0) ||
+ tproto = ACCESS_ONCE(t->parms.proto);
+ if ((tproto != IPPROTO_IPIP && tproto != 0) ||
!ip6_tnl_xmit_ctl(t))
return -1;
@@ -1120,9 +1126,11 @@
struct flowi6 fl6;
__u8 dsfield;
__u32 mtu;
+ u8 tproto;
int err;
- if ((t->parms.proto != IPPROTO_IPV6 && t->parms.proto != 0) ||
+ tproto = ACCESS_ONCE(t->parms.proto);
+ if ((tproto != IPPROTO_IPV6 && tproto != 0) ||
!ip6_tnl_xmit_ctl(t) || ip6_tnl_addr_conflict(t, ipv6h))
return -1;
@@ -1285,6 +1293,14 @@
return err;
}
+static int ip6_tnl0_update(struct ip6_tnl *t, struct __ip6_tnl_parm *p)
+{
+ /* for default tnl0 device allow to change only the proto */
+ t->parms.proto = p->proto;
+ netdev_state_change(t->dev);
+ return 0;
+}
+
static void
ip6_tnl_parm_from_user(struct __ip6_tnl_parm *p, const struct ip6_tnl_parm *u)
{
@@ -1384,7 +1400,7 @@
break;
ip6_tnl_parm_from_user(&p1, &p);
t = ip6_tnl_locate(net, &p1, cmd == SIOCADDTUNNEL);
- if (dev != ip6n->fb_tnl_dev && cmd == SIOCCHGTUNNEL) {
+ if (cmd == SIOCCHGTUNNEL) {
if (t != NULL) {
if (t->dev != dev) {
err = -EEXIST;
@@ -1392,8 +1408,10 @@
}
} else
t = netdev_priv(dev);
-
- err = ip6_tnl_update(t, &p1);
+ if (dev == ip6n->fb_tnl_dev)
+ err = ip6_tnl0_update(t, &p1);
+ else
+ err = ip6_tnl_update(t, &p1);
}
if (t) {
err = 0;