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Commit 42240901 authored by Tom Herbert's avatar Tom Herbert Committed by David S. Miller
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ipv6: Implement different admin modes for automatic flow labels 



Change the meaning of net.ipv6.auto_flowlabels to provide a mode for
automatic flow labels generation. There are four modes:

0: flow labels are disabled
1: flow labels are enabled, sockets can opt-out
2: flow labels are allowed, sockets can opt-in
3: flow labels are enabled and enforced, no opt-out for sockets

np->autoflowlabel is initialized according to the sysctl value.

Signed-off-by: default avatarTom Herbert <tom@herbertland.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 67800f9b

Documentation/networking/ip-sysctl.txt

+13 −7
Original line number Diff line number Diff line
@@ -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

include/net/ipv6.h

+46 −13
Original line number Diff line number Diff line
@@ -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;



	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;



	hash = skb_get_hash_flowi6(skb, fl6);



	/* 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;

	rol32(hash, 16);



	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

net/ipv6/af_inet6.c

+2 −1
Original line number Diff line number Diff line
@@ -197,6 +197,7 @@ static int inet6_create(struct net *net, struct socket *sock, int 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;

net/ipv6/ip6_gre.c

+2 −2
Original line number Diff line number Diff line
@@ -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;

net/ipv6/ip6_tunnel.c

+1 −1
Original line number Diff line number Diff line
@@ -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;