ip6_tunnel, ip6_gre: fix setting of DSCP on encapsulated packets

This fix addresses two problems in the way the DSCP field is formulated
 on the encapsulating header of IPv6 tunnels.
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=195661

1) The IPv6 tunneling code was manipulating the DSCP field of the
 encapsulating packet using the 32b flowlabel. Since the flowlabel is
 only the lower 20b it was incorrect to assume that the upper 12b
 containing the DSCP and ECN fields would remain intact when formulating
 the encapsulating header. This fix handles the 'inherit' and
 'fixed-value' DSCP cases explicitly using the extant dsfield u8 variable.

2) The use of INET_ECN_encapsulate(0, dsfield) in ip6_tnl_xmit was
 incorrect and resulted in the DSCP value always being set to 0.

Commit 01c2384ce8e8 ("ipv6: fix flow labels when the traffic class
 is non-0") caused the regression by masking out the flowlabel
 which exposed the incorrect handling of the DSCP portion of the
 flowlabel in ip6_tunnel and ip6_gre.

Fixes: 01c2384ce8e8 ("ipv6: fix flow labels when the traffic class is non-0")
Signed-off-by: Peter Dawson <peter.a.dawson@boeing.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index 8d128ba79b66de52d4d60628fe8df6cc9bccbc3b..0c5b4caa19491eb04bc755032611c76f03008acb 100644 (file)
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -537,11 +537,10 @@ static inline int ip6gre_xmit_ipv4(struct sk_buff *skb, struct net_device *dev)
 
        memcpy(&fl6, &t->fl.u.ip6, sizeof(fl6));
 
-       dsfield = ipv4_get_dsfield(iph);
-
        if (t->parms.flags & IP6_TNL_F_USE_ORIG_TCLASS)
-               fl6.flowlabel |= htonl((__u32)iph->tos << IPV6_TCLASS_SHIFT)
-                                         & IPV6_TCLASS_MASK;
+               dsfield = ipv4_get_dsfield(iph);
+       else
+               dsfield = ip6_tclass(t->parms.flowinfo);
        if (t->parms.flags & IP6_TNL_F_USE_ORIG_FWMARK)
                fl6.flowi6_mark = skb->mark;
        else
@@ -598,9 +597,11 @@ static inline int ip6gre_xmit_ipv6(struct sk_buff *skb, struct net_device *dev)
 
        memcpy(&fl6, &t->fl.u.ip6, sizeof(fl6));
 
-       dsfield = ipv6_get_dsfield(ipv6h);
        if (t->parms.flags & IP6_TNL_F_USE_ORIG_TCLASS)
-               fl6.flowlabel |= (*(__be32 *) ipv6h & IPV6_TCLASS_MASK);
+               dsfield = ipv6_get_dsfield(ipv6h);
+       else
+               dsfield = ip6_tclass(t->parms.flowinfo);
+
        if (t->parms.flags & IP6_TNL_F_USE_ORIG_FLOWLABEL)
                fl6.flowlabel |= ip6_flowlabel(ipv6h);
        if (t->parms.flags & IP6_TNL_F_USE_ORIG_FWMARK)

diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index 6eb2ae507500b30959134aa3ed35c53c7b79aad9..7ae6c503f1ca2b089388598bfceb43e4aa2d2fea 100644 (file)
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -1196,7 +1196,7 @@ route_lookup:
        skb_push(skb, sizeof(struct ipv6hdr));
        skb_reset_network_header(skb);
        ipv6h = ipv6_hdr(skb);
-       ip6_flow_hdr(ipv6h, INET_ECN_encapsulate(0, dsfield),
+       ip6_flow_hdr(ipv6h, dsfield,
                     ip6_make_flowlabel(net, skb, fl6->flowlabel, true, fl6));
        ipv6h->hop_limit = hop_limit;
        ipv6h->nexthdr = proto;
@@ -1231,8 +1231,6 @@ ip4ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev)
        if (tproto != IPPROTO_IPIP && tproto != 0)
                return -1;
 
-       dsfield = ipv4_get_dsfield(iph);
-
        if (t->parms.collect_md) {
                struct ip_tunnel_info *tun_info;
                const struct ip_tunnel_key *key;
@@ -1246,6 +1244,7 @@ ip4ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev)
                fl6.flowi6_proto = IPPROTO_IPIP;
                fl6.daddr = key->u.ipv6.dst;
                fl6.flowlabel = key->label;
+               dsfield = ip6_tclass(key->label);
        } else {
                if (!(t->parms.flags & IP6_TNL_F_IGN_ENCAP_LIMIT))
                        encap_limit = t->parms.encap_limit;
@@ -1254,8 +1253,9 @@ ip4ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev)
                fl6.flowi6_proto = IPPROTO_IPIP;
 
                if (t->parms.flags & IP6_TNL_F_USE_ORIG_TCLASS)
-                       fl6.flowlabel |= htonl((__u32)iph->tos << IPV6_TCLASS_SHIFT)
-                                        & IPV6_TCLASS_MASK;
+                       dsfield = ipv4_get_dsfield(iph);
+               else
+                       dsfield = ip6_tclass(t->parms.flowinfo);
                if (t->parms.flags & IP6_TNL_F_USE_ORIG_FWMARK)
                        fl6.flowi6_mark = skb->mark;
                else
@@ -1267,6 +1267,8 @@ ip4ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev)
        if (iptunnel_handle_offloads(skb, SKB_GSO_IPXIP6))
                return -1;
 
+       dsfield = INET_ECN_encapsulate(dsfield, ipv4_get_dsfield(iph));
+
        skb_set_inner_ipproto(skb, IPPROTO_IPIP);
 
        err = ip6_tnl_xmit(skb, dev, dsfield, &fl6, encap_limit, &mtu,
@@ -1300,8 +1302,6 @@ ip6ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev)
            ip6_tnl_addr_conflict(t, ipv6h))
                return -1;
 
-       dsfield = ipv6_get_dsfield(ipv6h);
-
        if (t->parms.collect_md) {
                struct ip_tunnel_info *tun_info;
                const struct ip_tunnel_key *key;
@@ -1315,6 +1315,7 @@ ip6ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev)
                fl6.flowi6_proto = IPPROTO_IPV6;
                fl6.daddr = key->u.ipv6.dst;
                fl6.flowlabel = key->label;
+               dsfield = ip6_tclass(key->label);
        } else {
                offset = ip6_tnl_parse_tlv_enc_lim(skb, skb_network_header(skb));
                /* ip6_tnl_parse_tlv_enc_lim() might have reallocated skb->head */
@@ -1337,7 +1338,9 @@ ip6ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev)
                fl6.flowi6_proto = IPPROTO_IPV6;
 
                if (t->parms.flags & IP6_TNL_F_USE_ORIG_TCLASS)
-                       fl6.flowlabel |= (*(__be32 *)ipv6h & IPV6_TCLASS_MASK);
+                       dsfield = ipv6_get_dsfield(ipv6h);
+               else
+                       dsfield = ip6_tclass(t->parms.flowinfo);
                if (t->parms.flags & IP6_TNL_F_USE_ORIG_FLOWLABEL)
                        fl6.flowlabel |= ip6_flowlabel(ipv6h);
                if (t->parms.flags & IP6_TNL_F_USE_ORIG_FWMARK)
@@ -1351,6 +1354,8 @@ ip6ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev)
        if (iptunnel_handle_offloads(skb, SKB_GSO_IPXIP6))
                return -1;
 
+       dsfield = INET_ECN_encapsulate(dsfield, ipv6_get_dsfield(ipv6h));
+
        skb_set_inner_ipproto(skb, IPPROTO_IPV6);
 
        err = ip6_tnl_xmit(skb, dev, dsfield, &fl6, encap_limit, &mtu,