* [PATCH v2 bpf-next 1/3] net/ipv4: Add helper to return path MTU based on fib result
2018-05-21 16:08 [PATCH v2 bpf-next 0/3] bpf: Add MTU check to fib lookup helper dsahern
@ 2018-05-21 16:08 ` dsahern
2018-05-21 16:08 ` [PATCH v2 bpf-next 2/3] net/ipv6: " dsahern
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: dsahern @ 2018-05-21 16:08 UTC (permalink / raw)
To: netdev, borkmann, ast; +Cc: davem, David Ahern
From: David Ahern <dsahern@gmail.com>
Determine path MTU from a FIB lookup result. Logic is a distillation of
ip_dst_mtu_maybe_forward.
Signed-off-by: David Ahern <dsahern@gmail.com>
---
include/net/ip_fib.h | 2 ++
net/ipv4/route.c | 31 +++++++++++++++++++++++++++++++
2 files changed, 33 insertions(+)
diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h
index 81d0f2107ff1..69c91d1934c1 100644
--- a/include/net/ip_fib.h
+++ b/include/net/ip_fib.h
@@ -449,4 +449,6 @@ static inline void fib_proc_exit(struct net *net)
}
#endif
+u32 ip_mtu_from_fib_result(struct fib_result *res, __be32 daddr);
+
#endif /* _NET_FIB_H */
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 29268efad247..ac3b22bc51b2 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1352,6 +1352,37 @@ static struct fib_nh_exception *find_exception(struct fib_nh *nh, __be32 daddr)
return NULL;
}
+/* MTU selection:
+ * 1. mtu on route is locked - use it
+ * 2. mtu from nexthop exception
+ * 3. mtu from egress device
+ */
+
+u32 ip_mtu_from_fib_result(struct fib_result *res, __be32 daddr)
+{
+ struct fib_info *fi = res->fi;
+ struct fib_nh *nh = &fi->fib_nh[res->nh_sel];
+ struct net_device *dev = nh->nh_dev;
+ u32 mtu = 0;
+
+ if (dev_net(dev)->ipv4.sysctl_ip_fwd_use_pmtu ||
+ fi->fib_metrics->metrics[RTAX_LOCK - 1] & (1 << RTAX_MTU))
+ mtu = fi->fib_mtu;
+
+ if (likely(!mtu)) {
+ struct fib_nh_exception *fnhe;
+
+ fnhe = find_exception(nh, daddr);
+ if (fnhe && !time_after_eq(jiffies, fnhe->fnhe_expires))
+ mtu = fnhe->fnhe_pmtu;
+ }
+
+ if (likely(!mtu))
+ mtu = min(READ_ONCE(dev->mtu), IP_MAX_MTU);
+
+ return mtu - lwtunnel_headroom(nh->nh_lwtstate, mtu);
+}
+
static bool rt_bind_exception(struct rtable *rt, struct fib_nh_exception *fnhe,
__be32 daddr, const bool do_cache)
{
--
2.11.0
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH v2 bpf-next 2/3] net/ipv6: Add helper to return path MTU based on fib result
2018-05-21 16:08 [PATCH v2 bpf-next 0/3] bpf: Add MTU check to fib lookup helper dsahern
2018-05-21 16:08 ` [PATCH v2 bpf-next 1/3] net/ipv4: Add helper to return path MTU based on fib result dsahern
@ 2018-05-21 16:08 ` dsahern
2018-05-21 16:08 ` [PATCH v2 bpf-next 3/3] bpf: Add mtu checking to FIB forwarding helper dsahern
2018-05-22 8:59 ` [PATCH v2 bpf-next 0/3] bpf: Add MTU check to fib lookup helper Daniel Borkmann
3 siblings, 0 replies; 5+ messages in thread
From: dsahern @ 2018-05-21 16:08 UTC (permalink / raw)
To: netdev, borkmann, ast; +Cc: davem, David Ahern
From: David Ahern <dsahern@gmail.com>
Determine path MTU from a FIB lookup result. Logic is based on
ip6_dst_mtu_forward plus lookup of nexthop exception.
Add ip6_dst_mtu_forward to ipv6_stubs to handle access by core
bpf code.
Signed-off-by: David Ahern <dsahern@gmail.com>
---
include/net/addrconf.h | 2 ++
include/net/ip6_fib.h | 6 ++++++
include/net/ip6_route.h | 3 +++
net/ipv6/addrconf_core.c | 8 ++++++++
net/ipv6/af_inet6.c | 1 +
net/ipv6/route.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
6 files changed, 68 insertions(+)
diff --git a/include/net/addrconf.h b/include/net/addrconf.h
index ff766ab207e0..c07d4dd09361 100644
--- a/include/net/addrconf.h
+++ b/include/net/addrconf.h
@@ -236,6 +236,8 @@ struct ipv6_stub {
struct flowi6 *fl6, int oif,
const struct sk_buff *skb,
int strict);
+ u32 (*ip6_mtu_from_fib6)(struct fib6_info *f6i, struct in6_addr *daddr,
+ struct in6_addr *saddr);
void (*udpv6_encap_enable)(void);
void (*ndisc_send_na)(struct net_device *dev, const struct in6_addr *daddr,
diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index cc70f6da8462..7897efe80727 100644
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -412,6 +412,12 @@ static inline struct net_device *fib6_info_nh_dev(const struct fib6_info *f6i)
return f6i->fib6_nh.nh_dev;
}
+static inline
+struct lwtunnel_state *fib6_info_nh_lwt(const struct fib6_info *f6i)
+{
+ return f6i->fib6_nh.nh_lwtstate;
+}
+
void inet6_rt_notify(int event, struct fib6_info *rt, struct nl_info *info,
unsigned int flags);
diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
index 4cf1ef935ed9..7b9c82de11cc 100644
--- a/include/net/ip6_route.h
+++ b/include/net/ip6_route.h
@@ -300,6 +300,9 @@ static inline unsigned int ip6_dst_mtu_forward(const struct dst_entry *dst)
return mtu;
}
+u32 ip6_mtu_from_fib6(struct fib6_info *f6i, struct in6_addr *daddr,
+ struct in6_addr *saddr);
+
struct neighbour *ip6_neigh_lookup(const struct in6_addr *gw,
struct net_device *dev, struct sk_buff *skb,
const void *daddr);
diff --git a/net/ipv6/addrconf_core.c b/net/ipv6/addrconf_core.c
index 2fe754fd4f5e..5cd0029d930e 100644
--- a/net/ipv6/addrconf_core.c
+++ b/net/ipv6/addrconf_core.c
@@ -161,12 +161,20 @@ eafnosupport_fib6_multipath_select(const struct net *net, struct fib6_info *f6i,
return f6i;
}
+static u32
+eafnosupport_ip6_mtu_from_fib6(struct fib6_info *f6i, struct in6_addr *daddr,
+ struct in6_addr *saddr)
+{
+ return 0;
+}
+
const struct ipv6_stub *ipv6_stub __read_mostly = &(struct ipv6_stub) {
.ipv6_dst_lookup = eafnosupport_ipv6_dst_lookup,
.fib6_get_table = eafnosupport_fib6_get_table,
.fib6_table_lookup = eafnosupport_fib6_table_lookup,
.fib6_lookup = eafnosupport_fib6_lookup,
.fib6_multipath_select = eafnosupport_fib6_multipath_select,
+ .ip6_mtu_from_fib6 = eafnosupport_ip6_mtu_from_fib6,
};
EXPORT_SYMBOL_GPL(ipv6_stub);
diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index 50de8b0d4f70..9ed0eae91758 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -894,6 +894,7 @@ static const struct ipv6_stub ipv6_stub_impl = {
.fib6_table_lookup = fib6_table_lookup,
.fib6_lookup = fib6_lookup,
.fib6_multipath_select = fib6_multipath_select,
+ .ip6_mtu_from_fib6 = ip6_mtu_from_fib6,
.udpv6_encap_enable = udpv6_encap_enable,
.ndisc_send_na = ndisc_send_na,
.nd_tbl = &nd_tbl,
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index cc24ed3bc334..dc5d5c84dbef 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2603,6 +2603,54 @@ static unsigned int ip6_mtu(const struct dst_entry *dst)
return mtu - lwtunnel_headroom(dst->lwtstate, mtu);
}
+/* MTU selection:
+ * 1. mtu on route is locked - use it
+ * 2. mtu from nexthop exception
+ * 3. mtu from egress device
+ *
+ * based on ip6_dst_mtu_forward and exception logic of
+ * rt6_find_cached_rt; called with rcu_read_lock
+ */
+u32 ip6_mtu_from_fib6(struct fib6_info *f6i, struct in6_addr *daddr,
+ struct in6_addr *saddr)
+{
+ struct rt6_exception_bucket *bucket;
+ struct rt6_exception *rt6_ex;
+ struct in6_addr *src_key;
+ struct inet6_dev *idev;
+ u32 mtu = 0;
+
+ if (unlikely(fib6_metric_locked(f6i, RTAX_MTU))) {
+ mtu = f6i->fib6_pmtu;
+ if (mtu)
+ goto out;
+ }
+
+ src_key = NULL;
+#ifdef CONFIG_IPV6_SUBTREES
+ if (f6i->fib6_src.plen)
+ src_key = saddr;
+#endif
+
+ bucket = rcu_dereference(f6i->rt6i_exception_bucket);
+ rt6_ex = __rt6_find_exception_rcu(&bucket, daddr, src_key);
+ if (rt6_ex && !rt6_check_expired(rt6_ex->rt6i))
+ mtu = dst_metric_raw(&rt6_ex->rt6i->dst, RTAX_MTU);
+
+ if (likely(!mtu)) {
+ struct net_device *dev = fib6_info_nh_dev(f6i);
+
+ mtu = IPV6_MIN_MTU;
+ idev = __in6_dev_get(dev);
+ if (idev && idev->cnf.mtu6 > mtu)
+ mtu = idev->cnf.mtu6;
+ }
+
+ mtu = min_t(unsigned int, mtu, IP6_MAX_MTU);
+out:
+ return mtu - lwtunnel_headroom(fib6_info_nh_lwt(f6i), mtu);
+}
+
struct dst_entry *icmp6_dst_alloc(struct net_device *dev,
struct flowi6 *fl6)
{
--
2.11.0
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH v2 bpf-next 3/3] bpf: Add mtu checking to FIB forwarding helper
2018-05-21 16:08 [PATCH v2 bpf-next 0/3] bpf: Add MTU check to fib lookup helper dsahern
2018-05-21 16:08 ` [PATCH v2 bpf-next 1/3] net/ipv4: Add helper to return path MTU based on fib result dsahern
2018-05-21 16:08 ` [PATCH v2 bpf-next 2/3] net/ipv6: " dsahern
@ 2018-05-21 16:08 ` dsahern
2018-05-22 8:59 ` [PATCH v2 bpf-next 0/3] bpf: Add MTU check to fib lookup helper Daniel Borkmann
3 siblings, 0 replies; 5+ messages in thread
From: dsahern @ 2018-05-21 16:08 UTC (permalink / raw)
To: netdev, borkmann, ast; +Cc: davem, David Ahern
From: David Ahern <dsahern@gmail.com>
Add check that egress MTU can handle packet to be forwarded. If
the MTU is less than the packet length, return 0 meaning the
packet is expected to continue up the stack for help - eg.,
fragmenting the packet or sending an ICMP.
The XDP path needs to leverage the FIB entry for an MTU on the
route spec or an exception entry for a given destination. The
skb path lets is_skb_forwardable decide if the packet can be
sent.
Signed-off-by: David Ahern <dsahern@gmail.com>
---
net/core/filter.c | 42 +++++++++++++++++++++++++++++++++++-------
1 file changed, 35 insertions(+), 7 deletions(-)
diff --git a/net/core/filter.c b/net/core/filter.c
index aec5ebafb262..ba3ff5aa575a 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -4089,7 +4089,7 @@ static int bpf_fib_set_fwd_params(struct bpf_fib_lookup *params,
#if IS_ENABLED(CONFIG_INET)
static int bpf_ipv4_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
- u32 flags)
+ u32 flags, bool check_mtu)
{
struct in_device *in_dev;
struct neighbour *neigh;
@@ -4098,6 +4098,7 @@ static int bpf_ipv4_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
struct fib_nh *nh;
struct flowi4 fl4;
int err;
+ u32 mtu;
dev = dev_get_by_index_rcu(net, params->ifindex);
if (unlikely(!dev))
@@ -4149,6 +4150,12 @@ static int bpf_ipv4_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
if (res.fi->fib_nhs > 1)
fib_select_path(net, &res, &fl4, NULL);
+ if (check_mtu) {
+ mtu = ip_mtu_from_fib_result(&res, params->ipv4_dst);
+ if (params->tot_len > mtu)
+ return 0;
+ }
+
nh = &res.fi->fib_nh[res.nh_sel];
/* do not handle lwt encaps right now */
@@ -4177,7 +4184,7 @@ static int bpf_ipv4_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
#if IS_ENABLED(CONFIG_IPV6)
static int bpf_ipv6_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
- u32 flags)
+ u32 flags, bool check_mtu)
{
struct in6_addr *src = (struct in6_addr *) params->ipv6_src;
struct in6_addr *dst = (struct in6_addr *) params->ipv6_dst;
@@ -4188,6 +4195,7 @@ static int bpf_ipv6_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
struct flowi6 fl6;
int strict = 0;
int oif;
+ u32 mtu;
/* link local addresses are never forwarded */
if (rt6_need_strict(dst) || rt6_need_strict(src))
@@ -4250,6 +4258,12 @@ static int bpf_ipv6_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
fl6.flowi6_oif, NULL,
strict);
+ if (check_mtu) {
+ mtu = ipv6_stub->ip6_mtu_from_fib6(f6i, dst, src);
+ if (params->tot_len > mtu)
+ return 0;
+ }
+
if (f6i->fib6_nh.nh_lwtstate)
return 0;
@@ -4282,12 +4296,12 @@ BPF_CALL_4(bpf_xdp_fib_lookup, struct xdp_buff *, ctx,
#if IS_ENABLED(CONFIG_INET)
case AF_INET:
return bpf_ipv4_fib_lookup(dev_net(ctx->rxq->dev), params,
- flags);
+ flags, true);
#endif
#if IS_ENABLED(CONFIG_IPV6)
case AF_INET6:
return bpf_ipv6_fib_lookup(dev_net(ctx->rxq->dev), params,
- flags);
+ flags, true);
#endif
}
return 0;
@@ -4306,20 +4320,34 @@ static const struct bpf_func_proto bpf_xdp_fib_lookup_proto = {
BPF_CALL_4(bpf_skb_fib_lookup, struct sk_buff *, skb,
struct bpf_fib_lookup *, params, int, plen, u32, flags)
{
+ struct net *net = dev_net(skb->dev);
+ int index = 0;
+
if (plen < sizeof(*params))
return -EINVAL;
switch (params->family) {
#if IS_ENABLED(CONFIG_INET)
case AF_INET:
- return bpf_ipv4_fib_lookup(dev_net(skb->dev), params, flags);
+ index = bpf_ipv4_fib_lookup(net, params, flags, false);
+ break;
#endif
#if IS_ENABLED(CONFIG_IPV6)
case AF_INET6:
- return bpf_ipv6_fib_lookup(dev_net(skb->dev), params, flags);
+ index = bpf_ipv6_fib_lookup(net, params, flags, false);
+ break;
#endif
}
- return -ENOTSUPP;
+
+ if (index > 0) {
+ struct net_device *dev;
+
+ dev = dev_get_by_index_rcu(net, index);
+ if (!is_skb_forwardable(dev, skb))
+ index = 0;
+ }
+
+ return index;
}
static const struct bpf_func_proto bpf_skb_fib_lookup_proto = {
--
2.11.0
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH v2 bpf-next 0/3] bpf: Add MTU check to fib lookup helper
2018-05-21 16:08 [PATCH v2 bpf-next 0/3] bpf: Add MTU check to fib lookup helper dsahern
` (2 preceding siblings ...)
2018-05-21 16:08 ` [PATCH v2 bpf-next 3/3] bpf: Add mtu checking to FIB forwarding helper dsahern
@ 2018-05-22 8:59 ` Daniel Borkmann
3 siblings, 0 replies; 5+ messages in thread
From: Daniel Borkmann @ 2018-05-22 8:59 UTC (permalink / raw)
To: dsahern, netdev, borkmann, ast; +Cc: davem, David Ahern
On 05/21/2018 06:08 PM, dsahern@kernel.org wrote:
> From: David Ahern <dsahern@gmail.com>
>
> Packets that exceed the egress MTU can not be forwarded in the fast path.
> Add IPv4 and IPv6 MTU helpers that take a FIB lookup result (versus the
> typical dst path) and add the calls to bpf_ipv{4,6}_fib_lookup.
>
> v2
> - add ip6_mtu_from_fib6 to ipv6_stub
> - only call the new MTU helpers for fib lookups in XDP path; skb
> path uses is_skb_forwardable to determine if the packet can be
> sent via the egress device from the FIB lookup
>
> David Ahern (3):
> net/ipv4: Add helper to return path MTU based on fib result
> net/ipv6: Add helper to return path MTU based on fib result
> bpf: Add mtu checking to FIB forwarding helper
>
> include/net/addrconf.h | 2 ++
> include/net/ip6_fib.h | 6 ++++++
> include/net/ip6_route.h | 3 +++
> include/net/ip_fib.h | 2 ++
> net/core/filter.c | 42 +++++++++++++++++++++++++++++++++++-------
> net/ipv4/route.c | 31 +++++++++++++++++++++++++++++++
> net/ipv6/addrconf_core.c | 8 ++++++++
> net/ipv6/af_inet6.c | 1 +
> net/ipv6/route.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
> 9 files changed, 136 insertions(+), 7 deletions(-)
Applied to bpf-next, thanks David!
^ permalink raw reply [flat|nested] 5+ messages in thread