diff options
Diffstat (limited to 'target/linux/brcm2708/patches-4.4/0223-bpf-add-skb_postpush_rcsum-and-fix-dev_forward_skb-o.patch')
| -rw-r--r-- | target/linux/brcm2708/patches-4.4/0223-bpf-add-skb_postpush_rcsum-and-fix-dev_forward_skb-o.patch | 124 |
1 files changed, 124 insertions, 0 deletions
diff --git a/target/linux/brcm2708/patches-4.4/0223-bpf-add-skb_postpush_rcsum-and-fix-dev_forward_skb-o.patch b/target/linux/brcm2708/patches-4.4/0223-bpf-add-skb_postpush_rcsum-and-fix-dev_forward_skb-o.patch new file mode 100644 index 0000000000..1793d5e109 --- /dev/null +++ b/target/linux/brcm2708/patches-4.4/0223-bpf-add-skb_postpush_rcsum-and-fix-dev_forward_skb-o.patch @@ -0,0 +1,124 @@ +From 7ce01cd3013b7c9f1b257a6033b6d1f67fed5b5c Mon Sep 17 00:00:00 2001 +From: Daniel Borkmann <daniel@iogearbox.net> +Date: Thu, 7 Jan 2016 15:50:23 +0100 +Subject: [PATCH 223/232] 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> +--- + include/linux/skbuff.h | 17 +++++++++++++++++ + net/core/filter.c | 17 +++++++++++++---- + 2 files changed, 30 insertions(+), 4 deletions(-) + +--- a/include/linux/skbuff.h ++++ b/include/linux/skbuff.h +@@ -2737,6 +2737,23 @@ static inline void skb_postpull_rcsum(st + + unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len); + ++static inline void skb_postpush_rcsum(struct sk_buff *skb, ++ const void *start, unsigned int len) ++{ ++ /* For performing the reverse operation to skb_postpull_rcsum(), ++ * we can instead of ... ++ * ++ * skb->csum = csum_add(skb->csum, csum_partial(start, len, 0)); ++ * ++ * ... just use this equivalent version here to save a few ++ * instructions. Feeding csum of 0 in csum_partial() and later ++ * on adding skb->csum is equivalent to feed skb->csum in the ++ * first place. ++ */ ++ if (skb->ip_summed == CHECKSUM_COMPLETE) ++ skb->csum = csum_partial(start, len, skb->csum); ++} ++ + /** + * pskb_trim_rcsum - trim received skb and update checksum + * @skb: buffer to trim +--- a/net/core/filter.c ++++ b/net/core/filter.c +@@ -1288,8 +1288,9 @@ static u64 bpf_skb_store_bytes(u64 r1, u + /* 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; + } + +@@ -1415,8 +1416,12 @@ static u64 bpf_clone_redirect(u64 r1, u6 + 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); +@@ -1459,8 +1464,12 @@ 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); |