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authorPeter Oskolkov <posk@google.com>2019-02-13 11:53:37 -0800
committerAlexei Starovoitov <ast@kernel.org>2019-02-13 18:27:55 -0800
commitca78801a81e04a31f8088e96b2649a9cbace5499 (patch)
tree1fd2c1a1b785e58217ff93e8010acdb4a7473e0b /net/core/lwt_bpf.c
parent52f278774e796a553be0c869dcaaee6f259ca795 (diff)
bpf: handle GSO in bpf_lwt_push_encap
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; * 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. v8 changes: - make sure that if GRE or UDP encap is detected, there is enough of pushed bytes to cover both IP[v6] + GRE|UDP headers; - do not reject double-encapped packets; - whitelist TCP GSO packets rather than block SCTP GSO and UDP GSO. Signed-off-by: Peter Oskolkov <posk@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'net/core/lwt_bpf.c')
-rw-r--r--net/core/lwt_bpf.c67
1 files changed, 65 insertions, 2 deletions
diff --git a/net/core/lwt_bpf.c b/net/core/lwt_bpf.c
index e5a9850d9f48..079871fc020f 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;
@@ -390,10 +391,72 @@ static const struct lwtunnel_encap_ops bpf_encap_ops = {
.owner = THIS_MODULE,
};
+static int handle_gso_type(struct sk_buff *skb, unsigned int gso_type,
+ int encap_len)
+{
+ struct skb_shared_info *shinfo = skb_shinfo(skb);
+
+ 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)
{
- /* Handling of GSO-enabled packets is added in the next patch. */
- return -EOPNOTSUPP;
+ int next_hdr_offset;
+ void *next_hdr;
+ __u8 protocol;
+
+ /* SCTP and UDP_L4 gso need more nuanced handling than what
+ * handle_gso_type() does above: skb_decrease_gso_size() is not enough.
+ * So at the moment only TCP GSO packets are let through.
+ */
+ if (!(skb_shinfo(skb)->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6)))
+ return -ENOTSUPP;
+
+ if (ipv4) {
+ protocol = ip_hdr(skb)->protocol;
+ next_hdr_offset = sizeof(struct iphdr);
+ next_hdr = skb_network_header(skb) + next_hdr_offset;
+ } else {
+ protocol = ipv6_hdr(skb)->nexthdr;
+ next_hdr_offset = sizeof(struct ipv6hdr);
+ next_hdr = skb_network_header(skb) + next_hdr_offset;
+ }
+
+ switch (protocol) {
+ case IPPROTO_GRE:
+ next_hdr_offset += sizeof(struct gre_base_hdr);
+ if (next_hdr_offset > encap_len)
+ return -EINVAL;
+
+ 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:
+ next_hdr_offset += sizeof(struct udphdr);
+ if (next_hdr_offset > encap_len)
+ return -EINVAL;
+
+ 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)