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Diffstat (limited to '')
| -rw-r--r-- | samples/bpf/parse_varlen.c | 150 |
1 files changed, 150 insertions, 0 deletions
diff --git a/samples/bpf/parse_varlen.c b/samples/bpf/parse_varlen.c new file mode 100644 index 000000000..d8623846e --- /dev/null +++ b/samples/bpf/parse_varlen.c @@ -0,0 +1,150 @@ +/* Copyright (c) 2016 Facebook + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of version 2 of the GNU General Public + * License as published by the Free Software Foundation. + */ +#define KBUILD_MODNAME "foo" +#include <linux/if_ether.h> +#include <linux/if_vlan.h> +#include <linux/ip.h> +#include <linux/ipv6.h> +#include <linux/in.h> +#include <linux/tcp.h> +#include <linux/udp.h> +#include <uapi/linux/bpf.h> +#include <net/ip.h> +#include <bpf/bpf_helpers.h> + +#define DEFAULT_PKTGEN_UDP_PORT 9 +#define DEBUG 0 + +static int tcp(void *data, uint64_t tp_off, void *data_end) +{ + struct tcphdr *tcp = data + tp_off; + + if (tcp + 1 > data_end) + return 0; + if (tcp->dest == htons(80) || tcp->source == htons(80)) + return TC_ACT_SHOT; + return 0; +} + +static int udp(void *data, uint64_t tp_off, void *data_end) +{ + struct udphdr *udp = data + tp_off; + + if (udp + 1 > data_end) + return 0; + if (udp->dest == htons(DEFAULT_PKTGEN_UDP_PORT) || + udp->source == htons(DEFAULT_PKTGEN_UDP_PORT)) { + if (DEBUG) { + char fmt[] = "udp port 9 indeed\n"; + + bpf_trace_printk(fmt, sizeof(fmt)); + } + return TC_ACT_SHOT; + } + return 0; +} + +static int parse_ipv4(void *data, uint64_t nh_off, void *data_end) +{ + struct iphdr *iph; + uint64_t ihl_len; + + iph = data + nh_off; + if (iph + 1 > data_end) + return 0; + + if (ip_is_fragment(iph)) + return 0; + ihl_len = iph->ihl * 4; + + if (iph->protocol == IPPROTO_IPIP) { + iph = data + nh_off + ihl_len; + if (iph + 1 > data_end) + return 0; + ihl_len += iph->ihl * 4; + } + + if (iph->protocol == IPPROTO_TCP) + return tcp(data, nh_off + ihl_len, data_end); + else if (iph->protocol == IPPROTO_UDP) + return udp(data, nh_off + ihl_len, data_end); + return 0; +} + +static int parse_ipv6(void *data, uint64_t nh_off, void *data_end) +{ + struct ipv6hdr *ip6h; + struct iphdr *iph; + uint64_t ihl_len = sizeof(struct ipv6hdr); + uint64_t nexthdr; + + ip6h = data + nh_off; + if (ip6h + 1 > data_end) + return 0; + + nexthdr = ip6h->nexthdr; + + if (nexthdr == IPPROTO_IPIP) { + iph = data + nh_off + ihl_len; + if (iph + 1 > data_end) + return 0; + ihl_len += iph->ihl * 4; + nexthdr = iph->protocol; + } else if (nexthdr == IPPROTO_IPV6) { + ip6h = data + nh_off + ihl_len; + if (ip6h + 1 > data_end) + return 0; + ihl_len += sizeof(struct ipv6hdr); + nexthdr = ip6h->nexthdr; + } + + if (nexthdr == IPPROTO_TCP) + return tcp(data, nh_off + ihl_len, data_end); + else if (nexthdr == IPPROTO_UDP) + return udp(data, nh_off + ihl_len, data_end); + return 0; +} + +SEC("varlen") +int handle_ingress(struct __sk_buff *skb) +{ + void *data = (void *)(long)skb->data; + struct ethhdr *eth = data; + void *data_end = (void *)(long)skb->data_end; + uint64_t h_proto, nh_off; + + nh_off = sizeof(*eth); + if (data + nh_off > data_end) + return 0; + + h_proto = eth->h_proto; + + if (h_proto == ETH_P_8021Q || h_proto == ETH_P_8021AD) { + struct vlan_hdr *vhdr; + + vhdr = data + nh_off; + nh_off += sizeof(struct vlan_hdr); + if (data + nh_off > data_end) + return 0; + h_proto = vhdr->h_vlan_encapsulated_proto; + } + if (h_proto == ETH_P_8021Q || h_proto == ETH_P_8021AD) { + struct vlan_hdr *vhdr; + + vhdr = data + nh_off; + nh_off += sizeof(struct vlan_hdr); + if (data + nh_off > data_end) + return 0; + h_proto = vhdr->h_vlan_encapsulated_proto; + } + if (h_proto == htons(ETH_P_IP)) + return parse_ipv4(data, nh_off, data_end); + else if (h_proto == htons(ETH_P_IPV6)) + return parse_ipv6(data, nh_off, data_end); + return 0; +} +char _license[] SEC("license") = "GPL"; |