From: David Ahern <dsahern@gmail•com>
To: netdev@vger•kernel.org, borkmann@iogearbox•net, ast@kernel•org
Cc: davem@davemloft•net, David Ahern <dsahern@gmail•com>
Subject: [PATCH bpf-next 3/3] bpf: Add mtu checking to FIB forwarding helper
Date: Thu, 17 May 2018 09:09:30 -0700 [thread overview]
Message-ID: <20180517160930.25076-4-dsahern@gmail.com> (raw)
In-Reply-To: <20180517160930.25076-1-dsahern@gmail.com>
Add check that egress MTU can handle packet to be forwarded. If
the MTU is less than the packet lenght, return 0 meaning the
packet is expected to continue up the stack for help - eg.,
fragmenting the packet or sending an ICMP.
Signed-off-by: David Ahern <dsahern@gmail•com>
---
net/core/filter.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/net/core/filter.c b/net/core/filter.c
index 6d0d1560bd70..c47c47a75d4b 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -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 +4150,10 @@ 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);
+ 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 */
@@ -4188,6 +4193,7 @@ 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 +4256,10 @@ static int bpf_ipv6_fib_lookup(struct net *net, struct bpf_fib_lookup *params,
fl6.flowi6_oif, NULL,
strict);
+ mtu = ip6_mtu_from_fib6(f6i, dst, src);
+ if (params->tot_len > mtu)
+ return 0;
+
if (f6i->fib6_nh.nh_lwtstate)
return 0;
--
2.11.0
next prev parent reply other threads:[~2018-05-17 16:09 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-17 16:09 [PATCH bpf-next 0/3] bpf: Add MTU check to fib lookup helper David Ahern
2018-05-17 16:09 ` [PATCH bpf-next 1/3] net/ipv4: Add helper to return path MTU based on fib result David Ahern
2018-05-17 16:09 ` [PATCH bpf-next 2/3] net/ipv6: " David Ahern
2018-05-17 16:09 ` David Ahern [this message]
2018-05-17 22:22 ` [PATCH bpf-next 3/3] bpf: Add mtu checking to FIB forwarding helper Daniel Borkmann
2018-05-18 0:34 ` David Ahern
2018-05-18 14:01 ` Daniel Borkmann
2018-05-20 6:41 ` kbuild test robot
2018-05-20 11:14 ` kbuild test robot
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