6 files changed, 70 insertions, 25 deletions

diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index 00d26d919459..9ac3af3ab739 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -1215,14 +1215,20 @@ flowlabel_consistency - BOOLEAN
         FALSE: disabled
         Default: TRUE
 
-auto_flowlabels - BOOLEAN
-        Automatically generate flow labels based based on a flow hash
-        of the packet. This allows intermediate devices, such as routers,
-        to idenfify packet flows for mechanisms like Equal Cost Multipath
+auto_flowlabels - INTEGER
+        Automatically generate flow labels based on a flow hash of the
+        packet. This allows intermediate devices, such as routers, to
+        identify packet flows for mechanisms like Equal Cost Multipath
         Routing (see RFC 6438).
-        TRUE: enabled
-        FALSE: disabled
-        Default: false
+        0: automatic flow labels are completely disabled
+        1: automatic flow labels are enabled by default, they can be
+           disabled on a per socket basis using the IPV6_AUTOFLOWLABEL
+           socket option
+        2: automatic flow labels are allowed, they may be enabled on a
+           per socket basis using the IPV6_AUTOFLOWLABEL socket option
+        3: automatic flow labels are enabled and enforced, they cannot
+           be disabled by the socket option
+        Default: 0
 
 flowlabel_state_ranges - BOOLEAN
         Split the flow label number space into two ranges. 0-0x7FFFF is
diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 3e334b33ef3a..c02c1c03363a 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -707,36 +707,69 @@ static inline void iph_to_flow_copy_v6addrs(struct flow_keys *flow,
 }
 
 #if IS_ENABLED(CONFIG_IPV6)
+
+/* Sysctl settings for net ipv6.auto_flowlabels */
+#define IP6_AUTO_FLOW_LABEL_OFF         0
+#define IP6_AUTO_FLOW_LABEL_OPTOUT      1
+#define IP6_AUTO_FLOW_LABEL_OPTIN       2
+#define IP6_AUTO_FLOW_LABEL_FORCED      3
+
+#define IP6_AUTO_FLOW_LABEL_MAX         IP6_AUTO_FLOW_LABEL_FORCED
+
+#define IP6_DEFAULT_AUTO_FLOW_LABELS    IP6_AUTO_FLOW_LABEL_OFF
+
 static inline __be32 ip6_make_flowlabel(struct net *net, struct sk_buff *skb,
                                         __be32 flowlabel, bool autolabel,
                                         struct flowi6 *fl6)
 {
-        if (!flowlabel && (autolabel || net->ipv6.sysctl.auto_flowlabels)) {
-                u32 hash;
+        u32 hash;
 
-                hash = skb_get_hash_flowi6(skb, fl6);
+        if (flowlabel ||
+            net->ipv6.sysctl.auto_flowlabels == IP6_AUTO_FLOW_LABEL_OFF ||
+            (!autolabel &&
+             net->ipv6.sysctl.auto_flowlabels != IP6_AUTO_FLOW_LABEL_FORCED))
+                return flowlabel;
 
-                /* Since this is being sent on the wire obfuscate hash a bit
-                 * to minimize possbility that any useful information to an
-                 * attacker is leaked. Only lower 20 bits are relevant.
-                 */
-                hash ^= hash >> 12;
+        hash = skb_get_hash_flowi6(skb, fl6);
 
-                flowlabel = (__force __be32)hash & IPV6_FLOWLABEL_MASK;
+        /* Since this is being sent on the wire obfuscate hash a bit
+         * to minimize possbility that any useful information to an
+         * attacker is leaked. Only lower 20 bits are relevant.
+         */
+        rol32(hash, 16);
 
-                if (net->ipv6.sysctl.flowlabel_state_ranges)
-                        flowlabel |= IPV6_FLOWLABEL_STATELESS_FLAG;
-        }
+        flowlabel = (__force __be32)hash & IPV6_FLOWLABEL_MASK;
+
+        if (net->ipv6.sysctl.flowlabel_state_ranges)
+                flowlabel |= IPV6_FLOWLABEL_STATELESS_FLAG;
 
         return flowlabel;
 }
+
+static inline int ip6_default_np_autolabel(struct net *net)
+{
+        switch (net->ipv6.sysctl.auto_flowlabels) {
+        case IP6_AUTO_FLOW_LABEL_OFF:
+        case IP6_AUTO_FLOW_LABEL_OPTIN:
+        default:
+                return 0;
+        case IP6_AUTO_FLOW_LABEL_OPTOUT:
+        case IP6_AUTO_FLOW_LABEL_FORCED:
+                return 1;
+        }
+}
 #else
 static inline void ip6_set_txhash(struct sock *sk) { }
 static inline __be32 ip6_make_flowlabel(struct net *net, struct sk_buff *skb,
-                                        __be32 flowlabel, bool autolabel)
+                                        __be32 flowlabel, bool autolabel,
+                                        struct flowi6 *fl6)
 {
         return flowlabel;
 }
+static inline int ip6_default_np_autolabel(struct net *net)
+{
+        return 0;
+}
 #endif
 
 
diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index 7bc92ea4ae8f..3f0ae3a7c0b1 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -197,6 +197,7 @@ lookup_protocol:
         np->mcast_hops  = IPV6_DEFAULT_MCASTHOPS;
         np->mc_loop     = 1;
         np->pmtudisc    = IPV6_PMTUDISC_WANT;
+        np->autoflowlabel = ip6_default_np_autolabel(sock_net(sk));
         sk->sk_ipv6only = net->ipv6.sysctl.bindv6only;
 
         /* Init the ipv4 part of the socket since we can have sockets
@@ -767,7 +768,7 @@ static int __net_init inet6_net_init(struct net *net)
         net->ipv6.sysctl.bindv6only = 0;
         net->ipv6.sysctl.icmpv6_time = 1*HZ;
         net->ipv6.sysctl.flowlabel_consistency = 1;
-        net->ipv6.sysctl.auto_flowlabels = 0;
+        net->ipv6.sysctl.auto_flowlabels = IP6_DEFAULT_AUTO_FLOW_LABELS;
         net->ipv6.sysctl.idgen_retries = 3;
         net->ipv6.sysctl.idgen_delay = 1 * HZ;
         net->ipv6.sysctl.flowlabel_state_ranges = 1;
diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index a7d1ca2337a9..34f121812a14 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -728,7 +728,7 @@ static netdev_tx_t ip6gre_xmit2(struct sk_buff *skb,
          */
         ipv6h = ipv6_hdr(skb);
         ip6_flow_hdr(ipv6h, INET_ECN_encapsulate(0, dsfield),
-                     ip6_make_flowlabel(net, skb, fl6->flowlabel, false, fl6));
+                     ip6_make_flowlabel(net, skb, fl6->flowlabel, true, fl6));
         ipv6h->hop_limit = tunnel->parms.hop_limit;
         ipv6h->nexthdr = proto;
         ipv6h->saddr = fl6->saddr;
@@ -1182,7 +1182,7 @@ static int ip6gre_header(struct sk_buff *skb, struct net_device *dev,
 
         ip6_flow_hdr(ipv6h, 0,
                      ip6_make_flowlabel(dev_net(dev), skb,
-                                        t->fl.u.ip6.flowlabel, false,
+                                        t->fl.u.ip6.flowlabel, true,
                                         &t->fl.u.ip6));
         ipv6h->hop_limit = t->parms.hop_limit;
         ipv6h->nexthdr = NEXTHDR_GRE;
diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index 54e694c4af0e..b0ab420612bc 100644
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -1095,7 +1095,7 @@ static int ip6_tnl_xmit2(struct sk_buff *skb,
         skb_reset_network_header(skb);
         ipv6h = ipv6_hdr(skb);
         ip6_flow_hdr(ipv6h, INET_ECN_encapsulate(0, dsfield),
-                     ip6_make_flowlabel(net, skb, fl6->flowlabel, false, fl6));
+                     ip6_make_flowlabel(net, skb, fl6->flowlabel, true, fl6));
         ipv6h->hop_limit = t->parms.hop_limit;
         ipv6h->nexthdr = proto;
         ipv6h->saddr = fl6->saddr;
diff --git a/net/ipv6/sysctl_net_ipv6.c b/net/ipv6/sysctl_net_ipv6.c
index db48aebd9c47..45243bbe5253 100644
--- a/net/ipv6/sysctl_net_ipv6.c
+++ b/net/ipv6/sysctl_net_ipv6.c
@@ -17,6 +17,9 @@
 #include <net/inet_frag.h>
 
 static int one = 1;
+static int auto_flowlabels_min;
+static int auto_flowlabels_max = IP6_AUTO_FLOW_LABEL_MAX;
+
 
 static struct ctl_table ipv6_table_template[] = {
         {
@@ -45,7 +48,9 @@ static struct ctl_table ipv6_table_template[] = {
                 .data           = &init_net.ipv6.sysctl.auto_flowlabels,
                 .maxlen         = sizeof(int),
                 .mode           = 0644,
-                .proc_handler   = proc_dointvec
+                .proc_handler   = proc_dointvec_minmax,
+                .extra1         = &auto_flowlabels_min,
+                .extra2         = &auto_flowlabels_max
         },
         {
                 .procname       = "fwmark_reflect",