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ipv6: Implement different admin modes for automatic flow labels

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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: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Tom Herbert 2015-07-31 16:52:12 -07:00 committed by David S. Miller
parent 67800f9b1f
commit 42240901f7
6 changed files with 70 additions and 25 deletions
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20
Documentation/networking/ip-sysctl.txt
View File

@ -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

41
include/net/ipv6.h
View File

@ -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

3
net/ipv6/af_inet6.c
View File

@ -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;

4
net/ipv6/ip6_gre.c
View File

@ -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;

2
net/ipv6/ip6_tunnel.c
View File

@ -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;

7
net/ipv6/sysctl_net_ipv6.c
View File

@ -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",