diff options
| author | Daniel Borkmann <daniel@iogearbox.net> | 2016-01-07 17:50:23 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-01-11 01:54:28 +0300 |
| commit | f8ffad69c9f8b8dfb0b633425d4ef4d2493ba61a (patch) | |
| tree | 3b01575dd9d774bcfbeb65f0ca302d606a26f895 /net/core | |
| parent | fdc5432a7b44ab7de17141beec19d946b9344e91 (diff) | |
| download | linux-f8ffad69c9f8b8dfb0b633425d4ef4d2493ba61a.tar.xz | |
bpf: add skb_postpush_rcsum and fix dev_forward_skb occasions
Add a small helper skb_postpush_rcsum() and fix up redirect locations
that need CHECKSUM_COMPLETE fixups on ingress. dev_forward_skb() expects
a proper csum that covers also Ethernet header, f.e. since 2c26d34bbcc0
("net/core: Handle csum for CHECKSUM_COMPLETE VXLAN forwarding"), we
also do skb_postpull_rcsum() after pulling Ethernet header off via
eth_type_trans().
When using eBPF in a netns setup f.e. with vxlan in collect metadata mode,
I can trigger the following csum issue with an IPv6 setup:
[ 505.144065] dummy1: hw csum failure
[...]
[ 505.144108] Call Trace:
[ 505.144112] <IRQ> [<ffffffff81372f08>] dump_stack+0x44/0x5c
[ 505.144134] [<ffffffff81607cea>] netdev_rx_csum_fault+0x3a/0x40
[ 505.144142] [<ffffffff815fee3f>] __skb_checksum_complete+0xcf/0xe0
[ 505.144149] [<ffffffff816f0902>] nf_ip6_checksum+0xb2/0x120
[ 505.144161] [<ffffffffa08c0e0e>] icmpv6_error+0x17e/0x328 [nf_conntrack_ipv6]
[ 505.144170] [<ffffffffa0898eca>] ? ip6t_do_table+0x2fa/0x645 [ip6_tables]
[ 505.144177] [<ffffffffa08c0725>] ? ipv6_get_l4proto+0x65/0xd0 [nf_conntrack_ipv6]
[ 505.144189] [<ffffffffa06c9a12>] nf_conntrack_in+0xc2/0x5a0 [nf_conntrack]
[ 505.144196] [<ffffffffa08c039c>] ipv6_conntrack_in+0x1c/0x20 [nf_conntrack_ipv6]
[ 505.144204] [<ffffffff8164385d>] nf_iterate+0x5d/0x70
[ 505.144210] [<ffffffff816438d6>] nf_hook_slow+0x66/0xc0
[ 505.144218] [<ffffffff816bd302>] ipv6_rcv+0x3f2/0x4f0
[ 505.144225] [<ffffffff816bca40>] ? ip6_make_skb+0x1b0/0x1b0
[ 505.144232] [<ffffffff8160b77b>] __netif_receive_skb_core+0x36b/0x9a0
[ 505.144239] [<ffffffff8160bdc8>] ? __netif_receive_skb+0x18/0x60
[ 505.144245] [<ffffffff8160bdc8>] __netif_receive_skb+0x18/0x60
[ 505.144252] [<ffffffff8160ccff>] process_backlog+0x9f/0x140
[ 505.144259] [<ffffffff8160c4a5>] net_rx_action+0x145/0x320
[...]
What happens is that on ingress, we push Ethernet header back in, either
from cls_bpf or right before skb_do_redirect(), but without updating csum.
The "hw csum failure" can be fixed by using the new skb_postpush_rcsum()
helper for the dev_forward_skb() case to correct the csum diff again.
Thanks to Hannes Frederic Sowa for the csum_partial() idea!
Fixes: 3896d655f4d4 ("bpf: introduce bpf_clone_redirect() helper")
Fixes: 27b29f63058d ("bpf: add bpf_redirect() helper")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/filter.c | 17 |
1 files changed, 13 insertions, 4 deletions
diff --git a/net/core/filter.c b/net/core/filter.c index 35e6fed28709..0db92b5e2cbf 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -1368,8 +1368,9 @@ static u64 bpf_skb_store_bytes(u64 r1, u64 r2, u64 r3, u64 r4, u64 flags) /* skb_store_bits cannot return -EFAULT here */ skb_store_bits(skb, offset, ptr, len); - if (BPF_RECOMPUTE_CSUM(flags) && skb->ip_summed == CHECKSUM_COMPLETE) - skb->csum = csum_add(skb->csum, csum_partial(ptr, len, 0)); + if (BPF_RECOMPUTE_CSUM(flags)) + skb_postpush_rcsum(skb, ptr, len); + return 0; } @@ -1525,8 +1526,12 @@ static u64 bpf_clone_redirect(u64 r1, u64 ifindex, u64 flags, u64 r4, u64 r5) if (unlikely(!skb2)) return -ENOMEM; - if (BPF_IS_REDIRECT_INGRESS(flags)) + if (BPF_IS_REDIRECT_INGRESS(flags)) { + if (skb_at_tc_ingress(skb2)) + skb_postpush_rcsum(skb2, skb_mac_header(skb2), + skb2->mac_len); return dev_forward_skb(dev, skb2); + } skb2->dev = dev; skb_sender_cpu_clear(skb2); @@ -1569,8 +1574,12 @@ int skb_do_redirect(struct sk_buff *skb) return -EINVAL; } - if (BPF_IS_REDIRECT_INGRESS(ri->flags)) + if (BPF_IS_REDIRECT_INGRESS(ri->flags)) { + if (skb_at_tc_ingress(skb)) + skb_postpush_rcsum(skb, skb_mac_header(skb), + skb->mac_len); return dev_forward_skb(dev, skb); + } skb->dev = dev; skb_sender_cpu_clear(skb); |