[PATCH bpf-next v7 3/6] bpf: handle GSO in bpf_lwt_push_encap
From: Peter Oskolkov <hidden>
Date: 2019-02-07 00:37:37
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
This patch adds handling of GSO packets in bpf_lwt_push_ip_encap()
(called from bpf_lwt_push_encap):
* IPIP, GRE, and UDP encapsulation types are deduced by looking
into iphdr->protocol or ipv6hdr->next_header;
* an error is returned if the same GSO encap type is set on the skb;
* SCTP GSO packets are not supported (as bpf_skb_proto_4_to_6
and similar do);
* UDP_L4 GSO packets are also not supported (although they are
not blocked in bpf_skb_proto_4_to_6 and similar), as
skb_decrease_gso_size() will break it;
* SKB_GSO_DODGY bit is set.
Note: it may be possible to support SCTP and UDP_L4 gso packets;
but as these cases seem to be not well handled by other
tunneling/encapping code paths, the solution should
be generic enough to apply to all tunneling/encapping code.
Signed-off-by: Peter Oskolkov <redacted>
---
net/core/lwt_bpf.c | 62 +++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 59 insertions(+), 3 deletions(-)
diff --git a/net/core/lwt_bpf.c b/net/core/lwt_bpf.c
index 786b96148937..4ff60757bf23 100644
--- a/net/core/lwt_bpf.c
+++ b/net/core/lwt_bpf.c@@ -16,6 +16,7 @@ #include <linux/types.h> #include <linux/bpf.h> #include <net/lwtunnel.h> +#include <net/gre.h> struct bpf_lwt_prog { struct bpf_prog *prog;
@@ -390,15 +391,70 @@ static const struct lwtunnel_encap_ops bpf_encap_ops = { .owner = THIS_MODULE, }; -static int handle_gso_encap(struct sk_buff *skb, bool ipv4, int encap_len) +static int handle_gso_type(struct sk_buff *skb, unsigned int gso_type, + int encap_len) { - /* Handling of GSO-enabled packets is added in the next patch. */ - if (unlikely(skb_is_gso(skb))) + struct skb_shared_info *shinfo = skb_shinfo(skb); + + /* Refuse to double-encap with the same type. */ + if (shinfo->gso_type & gso_type) return -EINVAL; + gso_type |= SKB_GSO_DODGY; + shinfo->gso_type |= gso_type; + skb_decrease_gso_size(shinfo, encap_len); + shinfo->gso_segs = 0; return 0; } +static int handle_gso_encap(struct sk_buff *skb, bool ipv4, int encap_len) +{ + void *next_hdr; + __u8 protocol; + + if (!skb_is_gso(skb)) + return 0; + + /* SCTP and UDP_L4 gso need more nuanced handling than what + * handle_gso_type() does above: skb_decrease_gso_size() is not enough. + */ + if (unlikely(skb_shinfo(skb)->gso_type & + (SKB_GSO_SCTP | SKB_GSO_UDP_L4))) + return -ENOTSUPP; + + if (ipv4) { + protocol = ip_hdr(skb)->protocol; + next_hdr = skb_network_header(skb) + sizeof(struct iphdr); + } else { + protocol = ipv6_hdr(skb)->nexthdr; + next_hdr = skb_network_header(skb) + sizeof(struct ipv6hdr); + } + + switch (protocol) { + case IPPROTO_GRE: + if (((struct gre_base_hdr *)next_hdr)->flags & GRE_CSUM) + return handle_gso_type(skb, SKB_GSO_GRE_CSUM, + encap_len); + return handle_gso_type(skb, SKB_GSO_GRE, encap_len); + + case IPPROTO_UDP: + if (((struct udphdr *)next_hdr)->check) + return handle_gso_type(skb, SKB_GSO_UDP_TUNNEL_CSUM, + encap_len); + return handle_gso_type(skb, SKB_GSO_UDP_TUNNEL, encap_len); + + case IPPROTO_IP: + case IPPROTO_IPV6: + if (ipv4) + return handle_gso_type(skb, SKB_GSO_IPXIP4, encap_len); + else + return handle_gso_type(skb, SKB_GSO_IPXIP6, encap_len); + + default: + return -EPROTONOSUPPORT; + } +} + int bpf_lwt_push_ip_encap(struct sk_buff *skb, void *hdr, u32 len, bool ingress) { struct iphdr *iph;
--
2.20.1.611.gfbb209baf1-goog