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Message-Id: <1433990233-958-3-git-send-email-gospo@cumulusnetworks.com>
Date: Wed, 10 Jun 2015 22:37:12 -0400
From: Andy Gospodarek <gospo@...ulusnetworks.com>
To: netdev@...r.kernel.org, davem@...emloft.net,
ddutt@...ulusnetworks.com, sfeldma@...il.com,
alexander.duyck@...il.com, hannes@...essinduktion.org,
stephen@...workplumber.org
Cc: Andy Gospodarek <gospo@...ulusnetworks.com>
Subject: [PATCH net-next 2/3 v3] net: ipv4 sysctl option to ignore routes when nexthop link is down
This feature is only enabled with the new per-interface or ipv4 global
sysctls called 'ignore_routes_with_linkdown'.
net.ipv4.conf.all.ignore_routes_with_linkdown = 0
net.ipv4.conf.default.ignore_routes_with_linkdown = 0
net.ipv4.conf.lo.ignore_routes_with_linkdown = 0
...
When the above sysctls are set, will report to userspace that a route is
dead and will no longer resolve to this nexthop when performing a fib
lookup. This will signal to userspace that the route will not be
selected. The signalling of a RTNH_F_DEAD is only passed to userspace
if the sysctl is enabled and link is down. This was done as without it the
netlink listeners would have no idea whether or not a nexthop would be
selected. The kernel only sets RTNH_F_DEAD internally if the inteface has
IFF_UP cleared.
With the new sysctl set, the following behavior can be observed
(interface p8p1 is link-down):
default via 10.0.5.2 dev p9p1
10.0.5.0/24 dev p9p1 proto kernel scope link src 10.0.5.15
70.0.0.0/24 dev p7p1 proto kernel scope link src 70.0.0.1
80.0.0.0/24 dev p8p1 proto kernel scope link src 80.0.0.1 dead linkdown
90.0.0.0/24 via 80.0.0.2 dev p8p1 metric 1 dead linkdown
90.0.0.0/24 via 70.0.0.2 dev p7p1 metric 2
90.0.0.1 via 70.0.0.2 dev p7p1 src 70.0.0.1
cache
local 80.0.0.1 dev lo src 80.0.0.1
cache <local>
80.0.0.2 via 10.0.5.2 dev p9p1 src 10.0.5.15
cache
While the route does remain in the table (so it can be modified if
needed rather than being wiped away as it would be if IFF_UP was
cleared), the proper next-hop is chosen automatically when the link is
down. Now interface p8p1 is linked-up:
default via 10.0.5.2 dev p9p1
10.0.5.0/24 dev p9p1 proto kernel scope link src 10.0.5.15
70.0.0.0/24 dev p7p1 proto kernel scope link src 70.0.0.1
80.0.0.0/24 dev p8p1 proto kernel scope link src 80.0.0.1
90.0.0.0/24 via 80.0.0.2 dev p8p1 metric 1
90.0.0.0/24 via 70.0.0.2 dev p7p1 metric 2
192.168.56.0/24 dev p2p1 proto kernel scope link src 192.168.56.2
90.0.0.1 via 80.0.0.2 dev p8p1 src 80.0.0.1
cache
local 80.0.0.1 dev lo src 80.0.0.1
cache <local>
80.0.0.2 dev p8p1 src 80.0.0.1
cache
and the output changes to what one would expect.
If the sysctl is not set, the following output would be expected when
p8p1 is down:
default via 10.0.5.2 dev p9p1
10.0.5.0/24 dev p9p1 proto kernel scope link src 10.0.5.15
70.0.0.0/24 dev p7p1 proto kernel scope link src 70.0.0.1
80.0.0.0/24 dev p8p1 proto kernel scope link src 80.0.0.1 linkdown
90.0.0.0/24 via 80.0.0.2 dev p8p1 metric 1 linkdown
90.0.0.0/24 via 70.0.0.2 dev p7p1 metric 2
Since the dead flag does not appear, there should be no expectation that
the kernel would skip using this route due to link being down.
v2: Split kernel changes into 2 patches, this actually makes a
behavioral change if the sysctl is set. Also took suggestion from Alex
to simplify code by only checking sysctl during fib lookup and
suggestion from Scott to add a per-interface sysctl.
v3: Code clean-ups to make it more readable and efficient as well as a
reverse path check fix.
Signed-off-by: Andy Gospodarek <gospo@...ulusnetworks.com>
Signed-off-by: Dinesh Dutt <ddutt@...ulusnetworks.com>
---
include/linux/inetdevice.h | 3 +++
include/net/fib_rules.h | 3 ++-
include/net/ip_fib.h | 16 +++++++++-------
include/uapi/linux/ip.h | 1 +
include/uapi/linux/sysctl.h | 1 +
kernel/sysctl_binary.c | 1 +
net/ipv4/devinet.c | 2 ++
net/ipv4/fib_frontend.c | 6 +++---
net/ipv4/fib_rules.c | 5 +++--
net/ipv4/fib_semantics.c | 29 ++++++++++++++++++++++++-----
net/ipv4/fib_trie.c | 7 +++++++
net/ipv4/netfilter/ipt_rpfilter.c | 2 +-
net/ipv4/route.c | 10 +++++-----
13 files changed, 62 insertions(+), 24 deletions(-)
diff --git a/include/linux/inetdevice.h b/include/linux/inetdevice.h
index 0a21fbe..a4328ce 100644
--- a/include/linux/inetdevice.h
+++ b/include/linux/inetdevice.h
@@ -120,6 +120,9 @@ static inline void ipv4_devconf_setall(struct in_device *in_dev)
|| (!IN_DEV_FORWARD(in_dev) && \
IN_DEV_ORCONF((in_dev), ACCEPT_REDIRECTS)))
+#define IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) \
+ IN_DEV_CONF_GET((in_dev), IGNORE_ROUTES_WITH_LINKDOWN)
+
#define IN_DEV_ARPFILTER(in_dev) IN_DEV_ORCONF((in_dev), ARPFILTER)
#define IN_DEV_ARP_ACCEPT(in_dev) IN_DEV_ORCONF((in_dev), ARP_ACCEPT)
#define IN_DEV_ARP_ANNOUNCE(in_dev) IN_DEV_MAXCONF((in_dev), ARP_ANNOUNCE)
diff --git a/include/net/fib_rules.h b/include/net/fib_rules.h
index 6d67383..903a55e 100644
--- a/include/net/fib_rules.h
+++ b/include/net/fib_rules.h
@@ -36,7 +36,8 @@ struct fib_lookup_arg {
void *result;
struct fib_rule *rule;
int flags;
-#define FIB_LOOKUP_NOREF 1
+#define FIB_LOOKUP_NOREF 1
+#define FIB_LOOKUP_IGNORE_LINKSTATE 2
};
struct fib_rules_ops {
diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h
index f73d27c..49c142b 100644
--- a/include/net/ip_fib.h
+++ b/include/net/ip_fib.h
@@ -226,7 +226,7 @@ static inline struct fib_table *fib_new_table(struct net *net, u32 id)
}
static inline int fib_lookup(struct net *net, const struct flowi4 *flp,
- struct fib_result *res)
+ struct fib_result *res, unsigned int flags)
{
struct fib_table *tb;
int err = -ENETUNREACH;
@@ -234,7 +234,7 @@ static inline int fib_lookup(struct net *net, const struct flowi4 *flp,
rcu_read_lock();
tb = fib_get_table(net, RT_TABLE_MAIN);
- if (tb && !fib_table_lookup(tb, flp, res, FIB_LOOKUP_NOREF))
+ if (tb && !fib_table_lookup(tb, flp, res, flags | FIB_LOOKUP_NOREF))
err = 0;
rcu_read_unlock();
@@ -249,16 +249,18 @@ void __net_exit fib4_rules_exit(struct net *net);
struct fib_table *fib_new_table(struct net *net, u32 id);
struct fib_table *fib_get_table(struct net *net, u32 id);
-int __fib_lookup(struct net *net, struct flowi4 *flp, struct fib_result *res);
+int __fib_lookup(struct net *net, struct flowi4 *flp,
+ struct fib_result *res, unsigned int flags);
static inline int fib_lookup(struct net *net, struct flowi4 *flp,
- struct fib_result *res)
+ struct fib_result *res, unsigned int flags)
{
struct fib_table *tb;
int err;
+ flags |= FIB_LOOKUP_NOREF;
if (net->ipv4.fib_has_custom_rules)
- return __fib_lookup(net, flp, res);
+ return __fib_lookup(net, flp, res, flags);
rcu_read_lock();
@@ -266,11 +268,11 @@ static inline int fib_lookup(struct net *net, struct flowi4 *flp,
for (err = 0; !err; err = -ENETUNREACH) {
tb = rcu_dereference_rtnl(net->ipv4.fib_main);
- if (tb && !fib_table_lookup(tb, flp, res, FIB_LOOKUP_NOREF))
+ if (tb && !fib_table_lookup(tb, flp, res, flags))
break;
tb = rcu_dereference_rtnl(net->ipv4.fib_default);
- if (tb && !fib_table_lookup(tb, flp, res, FIB_LOOKUP_NOREF))
+ if (tb && !fib_table_lookup(tb, flp, res, flags))
break;
}
diff --git a/include/uapi/linux/ip.h b/include/uapi/linux/ip.h
index 4119594..08f894d 100644
--- a/include/uapi/linux/ip.h
+++ b/include/uapi/linux/ip.h
@@ -164,6 +164,7 @@ enum
IPV4_DEVCONF_ROUTE_LOCALNET,
IPV4_DEVCONF_IGMPV2_UNSOLICITED_REPORT_INTERVAL,
IPV4_DEVCONF_IGMPV3_UNSOLICITED_REPORT_INTERVAL,
+ IPV4_DEVCONF_IGNORE_ROUTES_WITH_LINKDOWN,
__IPV4_DEVCONF_MAX
};
diff --git a/include/uapi/linux/sysctl.h b/include/uapi/linux/sysctl.h
index 0956373..62fda94 100644
--- a/include/uapi/linux/sysctl.h
+++ b/include/uapi/linux/sysctl.h
@@ -482,6 +482,7 @@ enum
NET_IPV4_CONF_PROMOTE_SECONDARIES=20,
NET_IPV4_CONF_ARP_ACCEPT=21,
NET_IPV4_CONF_ARP_NOTIFY=22,
+ NET_IPV4_CONF_IGNORE_ROUTES_WITH_LINKDOWN=23,
};
/* /proc/sys/net/ipv4/netfilter */
diff --git a/kernel/sysctl_binary.c b/kernel/sysctl_binary.c
index 7e7746a..c9d0a0e 100644
--- a/kernel/sysctl_binary.c
+++ b/kernel/sysctl_binary.c
@@ -253,6 +253,7 @@ static const struct bin_table bin_net_ipv4_conf_vars_table[] = {
{ CTL_INT, NET_IPV4_CONF_NOPOLICY, "disable_policy" },
{ CTL_INT, NET_IPV4_CONF_FORCE_IGMP_VERSION, "force_igmp_version" },
{ CTL_INT, NET_IPV4_CONF_PROMOTE_SECONDARIES, "promote_secondaries" },
+ { CTL_INT, NET_IPV4_CONF_IGNORE_ROUTES_WITH_LINKDOWN, "ignore_routes_with_linkdown" },
{}
};
diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 419d23c..7498716 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -2169,6 +2169,8 @@ static struct devinet_sysctl_table {
"igmpv2_unsolicited_report_interval"),
DEVINET_SYSCTL_RW_ENTRY(IGMPV3_UNSOLICITED_REPORT_INTERVAL,
"igmpv3_unsolicited_report_interval"),
+ DEVINET_SYSCTL_RW_ENTRY(IGNORE_ROUTES_WITH_LINKDOWN,
+ "ignore_routes_with_linkdown"),
DEVINET_SYSCTL_FLUSHING_ENTRY(NOXFRM, "disable_xfrm"),
DEVINET_SYSCTL_FLUSHING_ENTRY(NOPOLICY, "disable_policy"),
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index 872defb..b566b7f 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -280,7 +280,7 @@ __be32 fib_compute_spec_dst(struct sk_buff *skb)
fl4.flowi4_tos = RT_TOS(ip_hdr(skb)->tos);
fl4.flowi4_scope = scope;
fl4.flowi4_mark = IN_DEV_SRC_VMARK(in_dev) ? skb->mark : 0;
- if (!fib_lookup(net, &fl4, &res))
+ if (!fib_lookup(net, &fl4, &res, 0))
return FIB_RES_PREFSRC(net, res);
} else {
scope = RT_SCOPE_LINK;
@@ -319,7 +319,7 @@ static int __fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst,
fl4.flowi4_mark = IN_DEV_SRC_VMARK(idev) ? skb->mark : 0;
net = dev_net(dev);
- if (fib_lookup(net, &fl4, &res))
+ if (fib_lookup(net, &fl4, &res, 0))
goto last_resort;
if (res.type != RTN_UNICAST &&
(res.type != RTN_LOCAL || !IN_DEV_ACCEPT_LOCAL(idev)))
@@ -354,7 +354,7 @@ static int __fib_validate_source(struct sk_buff *skb, __be32 src, __be32 dst,
fl4.flowi4_oif = dev->ifindex;
ret = 0;
- if (fib_lookup(net, &fl4, &res) == 0) {
+ if (fib_lookup(net, &fl4, &res, FIB_LOOKUP_IGNORE_LINKSTATE) == 0) {
if (res.type == RTN_UNICAST)
ret = FIB_RES_NH(res).nh_scope >= RT_SCOPE_HOST;
}
diff --git a/net/ipv4/fib_rules.c b/net/ipv4/fib_rules.c
index 5615198..18123d5 100644
--- a/net/ipv4/fib_rules.c
+++ b/net/ipv4/fib_rules.c
@@ -47,11 +47,12 @@ struct fib4_rule {
#endif
};
-int __fib_lookup(struct net *net, struct flowi4 *flp, struct fib_result *res)
+int __fib_lookup(struct net *net, struct flowi4 *flp,
+ struct fib_result *res, unsigned int flags)
{
struct fib_lookup_arg arg = {
.result = res,
- .flags = FIB_LOOKUP_NOREF,
+ .flags = flags,
};
int err;
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index 496507f..6cb49f6 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -623,7 +623,8 @@ static int fib_check_nh(struct fib_config *cfg, struct fib_info *fi,
/* It is not necessary, but requires a bit of thinking */
if (fl4.flowi4_scope < RT_SCOPE_LINK)
fl4.flowi4_scope = RT_SCOPE_LINK;
- err = fib_lookup(net, &fl4, &res);
+ err = fib_lookup(net, &fl4, &res,
+ FIB_LOOKUP_IGNORE_LINKSTATE);
if (err) {
rcu_read_unlock();
return err;
@@ -1035,12 +1036,18 @@ int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event,
nla_put_in_addr(skb, RTA_PREFSRC, fi->fib_prefsrc))
goto nla_put_failure;
if (fi->fib_nhs == 1) {
+ struct in_device *in_dev;
if (fi->fib_nh->nh_gw &&
nla_put_in_addr(skb, RTA_GATEWAY, fi->fib_nh->nh_gw))
goto nla_put_failure;
if (fi->fib_nh->nh_oif &&
nla_put_u32(skb, RTA_OIF, fi->fib_nh->nh_oif))
goto nla_put_failure;
+ if (fi->fib_nh->nh_flags & RTNH_F_LINKDOWN) {
+ in_dev = __in_dev_get_rcu(fi->fib_nh->nh_dev);
+ if (in_dev && IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev))
+ rtm->rtm_flags |= RTNH_F_DEAD;
+ }
#ifdef CONFIG_IP_ROUTE_CLASSID
if (fi->fib_nh[0].nh_tclassid &&
nla_put_u32(skb, RTA_FLOW, fi->fib_nh[0].nh_tclassid))
@@ -1057,11 +1064,17 @@ int fib_dump_info(struct sk_buff *skb, u32 portid, u32 seq, int event,
goto nla_put_failure;
for_nexthops(fi) {
+ struct in_device *in_dev;
rtnh = nla_reserve_nohdr(skb, sizeof(*rtnh));
if (!rtnh)
goto nla_put_failure;
rtnh->rtnh_flags = nh->nh_flags & 0xFF;
+ if (nh->nh_flags & RTNH_F_LINKDOWN) {
+ in_dev = __in_dev_get_rcu(nh->nh_dev);
+ if (in_dev && IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev))
+ rtnh->rtnh_flags |= RTNH_F_DEAD;
+ }
rtnh->rtnh_hops = nh->nh_weight - 1;
rtnh->rtnh_ifindex = nh->nh_oif;
@@ -1309,16 +1322,22 @@ int fib_sync_up(struct net_device *dev, unsigned int nh_flags)
void fib_select_multipath(struct fib_result *res)
{
struct fib_info *fi = res->fi;
+ struct in_device *in_dev;
int w;
spin_lock_bh(&fib_multipath_lock);
if (fi->fib_power <= 0) {
int power = 0;
change_nexthops(fi) {
- if (!(nexthop_nh->nh_flags & RTNH_F_DEAD)) {
- power += nexthop_nh->nh_weight;
- nexthop_nh->nh_power = nexthop_nh->nh_weight;
- }
+ in_dev = __in_dev_get_rcu(nexthop_nh->nh_dev);
+ if (nexthop_nh->nh_flags & RTNH_F_DEAD)
+ continue;
+ if (in_dev &&
+ IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
+ nexthop_nh->nh_flags & RTNH_F_LINKDOWN)
+ continue;
+ power += nexthop_nh->nh_weight;
+ nexthop_nh->nh_power = nexthop_nh->nh_weight;
} endfor_nexthops(fi);
fi->fib_power = power;
if (power <= 0) {
diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index 3c699c4..f75ca20 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -1407,11 +1407,18 @@ found:
}
if (fi->fib_flags & RTNH_F_DEAD)
continue;
+
for (nhsel = 0; nhsel < fi->fib_nhs; nhsel++) {
const struct fib_nh *nh = &fi->fib_nh[nhsel];
+ struct in_device *in_dev = __in_dev_get_rcu(nh->nh_dev);
if (nh->nh_flags & RTNH_F_DEAD)
continue;
+ if (in_dev &&
+ IN_DEV_IGNORE_ROUTES_WITH_LINKDOWN(in_dev) &&
+ nh->nh_flags & RTNH_F_LINKDOWN &&
+ !(fib_flags & FIB_LOOKUP_IGNORE_LINKSTATE))
+ continue;
if (flp->flowi4_oif && flp->flowi4_oif != nh->nh_oif)
continue;
diff --git a/net/ipv4/netfilter/ipt_rpfilter.c b/net/ipv4/netfilter/ipt_rpfilter.c
index 4bfaedf..8618fd1 100644
--- a/net/ipv4/netfilter/ipt_rpfilter.c
+++ b/net/ipv4/netfilter/ipt_rpfilter.c
@@ -40,7 +40,7 @@ static bool rpfilter_lookup_reverse(struct flowi4 *fl4,
struct net *net = dev_net(dev);
int ret __maybe_unused;
- if (fib_lookup(net, fl4, &res))
+ if (fib_lookup(net, fl4, &res, FIB_LOOKUP_IGNORE_LINKSTATE))
return false;
if (res.type != RTN_UNICAST) {
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index f605598..d0362a2 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -747,7 +747,7 @@ static void __ip_do_redirect(struct rtable *rt, struct sk_buff *skb, struct flow
if (!(n->nud_state & NUD_VALID)) {
neigh_event_send(n, NULL);
} else {
- if (fib_lookup(net, fl4, &res) == 0) {
+ if (fib_lookup(net, fl4, &res, 0) == 0) {
struct fib_nh *nh = &FIB_RES_NH(res);
update_or_create_fnhe(nh, fl4->daddr, new_gw,
@@ -975,7 +975,7 @@ static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu)
return;
rcu_read_lock();
- if (fib_lookup(dev_net(dst->dev), fl4, &res) == 0) {
+ if (fib_lookup(dev_net(dst->dev), fl4, &res, 0) == 0) {
struct fib_nh *nh = &FIB_RES_NH(res);
update_or_create_fnhe(nh, fl4->daddr, 0, mtu,
@@ -1186,7 +1186,7 @@ void ip_rt_get_source(u8 *addr, struct sk_buff *skb, struct rtable *rt)
fl4.flowi4_mark = skb->mark;
rcu_read_lock();
- if (fib_lookup(dev_net(rt->dst.dev), &fl4, &res) == 0)
+ if (fib_lookup(dev_net(rt->dst.dev), &fl4, &res, 0) == 0)
src = FIB_RES_PREFSRC(dev_net(rt->dst.dev), res);
else
src = inet_select_addr(rt->dst.dev,
@@ -1716,7 +1716,7 @@ static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
fl4.flowi4_scope = RT_SCOPE_UNIVERSE;
fl4.daddr = daddr;
fl4.saddr = saddr;
- err = fib_lookup(net, &fl4, &res);
+ err = fib_lookup(net, &fl4, &res, 0);
if (err != 0) {
if (!IN_DEV_FORWARD(in_dev))
err = -EHOSTUNREACH;
@@ -2123,7 +2123,7 @@ struct rtable *__ip_route_output_key(struct net *net, struct flowi4 *fl4)
goto make_route;
}
- if (fib_lookup(net, fl4, &res)) {
+ if (fib_lookup(net, fl4, &res, 0)) {
res.fi = NULL;
res.table = NULL;
if (fl4->flowi4_oif) {
--
1.9.3
--
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