From 7a67e69a339a6824be2fc483073782ab2f47fcd2 Mon Sep 17 00:00:00 2001 From: Stefano Brivio Date: Thu, 15 Mar 2018 17:17:12 +0100 Subject: [PATCH] vti6: Keep set MTU on link creation or change, validate it In vti6_link_config(), if MTU is already given on link creation or change, validate and use it instead of recomputing it. To do that, we need to propagate the knowledge that MTU was set by userspace all the way down to vti6_link_config(). To keep this simple, vti6_dev_init() sets the new 'keep_mtu' argument of vti6_link_config() to true: on initialization, we don't have convenient access to netlink attributes there, but we will anyway check whether dev->mtu is set in vti6_link_config(). If it's non-zero, it was set to the value of the IFLA_MTU attribute during creation. Otherwise, determine a reasonable value. Fixes: ed1efb2aefbb ("ipv6: Add support for IPsec virtual tunnel interfaces") Fixes: 53c81e95df17 ("ip6_vti: adjust vti mtu according to mtu of lower device") Signed-off-by: Stefano Brivio Acked-by: Sabrina Dubroca Signed-off-by: Steffen Klassert --- net/ipv6/ip6_vti.c | 24 ++++++++++++++++-------- 1 file changed, 16 insertions(+), 8 deletions(-) diff --git a/net/ipv6/ip6_vti.c b/net/ipv6/ip6_vti.c index 2ceef41cc097..971175142e14 100644 --- a/net/ipv6/ip6_vti.c +++ b/net/ipv6/ip6_vti.c @@ -622,7 +622,7 @@ static int vti6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, return 0; } -static void vti6_link_config(struct ip6_tnl *t) +static void vti6_link_config(struct ip6_tnl *t, bool keep_mtu) { struct net_device *dev = t->dev; struct __ip6_tnl_parm *p = &t->parms; @@ -641,6 +641,11 @@ static void vti6_link_config(struct ip6_tnl *t) else dev->flags &= ~IFF_POINTOPOINT; + if (keep_mtu && dev->mtu) { + dev->mtu = clamp(dev->mtu, dev->min_mtu, dev->max_mtu); + return; + } + if (p->flags & IP6_TNL_F_CAP_XMIT) { int strict = (ipv6_addr_type(&p->raddr) & (IPV6_ADDR_MULTICAST | IPV6_ADDR_LINKLOCAL)); @@ -668,12 +673,14 @@ static void vti6_link_config(struct ip6_tnl *t) * vti6_tnl_change - update the tunnel parameters * @t: tunnel to be changed * @p: tunnel configuration parameters + * @keep_mtu: MTU was set from userspace, don't re-compute it * * Description: * vti6_tnl_change() updates the tunnel parameters **/ static int -vti6_tnl_change(struct ip6_tnl *t, const struct __ip6_tnl_parm *p) +vti6_tnl_change(struct ip6_tnl *t, const struct __ip6_tnl_parm *p, + bool keep_mtu) { t->parms.laddr = p->laddr; t->parms.raddr = p->raddr; @@ -683,11 +690,12 @@ vti6_tnl_change(struct ip6_tnl *t, const struct __ip6_tnl_parm *p) t->parms.proto = p->proto; t->parms.fwmark = p->fwmark; dst_cache_reset(&t->dst_cache); - vti6_link_config(t); + vti6_link_config(t, keep_mtu); return 0; } -static int vti6_update(struct ip6_tnl *t, struct __ip6_tnl_parm *p) +static int vti6_update(struct ip6_tnl *t, struct __ip6_tnl_parm *p, + bool keep_mtu) { struct net *net = dev_net(t->dev); struct vti6_net *ip6n = net_generic(net, vti6_net_id); @@ -695,7 +703,7 @@ static int vti6_update(struct ip6_tnl *t, struct __ip6_tnl_parm *p) vti6_tnl_unlink(ip6n, t); synchronize_net(); - err = vti6_tnl_change(t, p); + err = vti6_tnl_change(t, p, keep_mtu); vti6_tnl_link(ip6n, t); netdev_state_change(t->dev); return err; @@ -808,7 +816,7 @@ vti6_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd) } else t = netdev_priv(dev); - err = vti6_update(t, &p1); + err = vti6_update(t, &p1, false); } if (t) { err = 0; @@ -907,7 +915,7 @@ static int vti6_dev_init(struct net_device *dev) if (err) return err; - vti6_link_config(t); + vti6_link_config(t, true); return 0; } @@ -1012,7 +1020,7 @@ static int vti6_changelink(struct net_device *dev, struct nlattr *tb[], } else t = netdev_priv(dev); - return vti6_update(t, &p); + return vti6_update(t, &p, tb && tb[IFLA_MTU]); } static size_t vti6_get_size(const struct net_device *dev) -- 2.30.2