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Diffstat (limited to 'samples/bpf/test_lwt_bpf.c')
| -rw-r--r-- | samples/bpf/test_lwt_bpf.c | 253 |
1 files changed, 253 insertions, 0 deletions
diff --git a/samples/bpf/test_lwt_bpf.c b/samples/bpf/test_lwt_bpf.c new file mode 100644 index 000000000..1b568575a --- /dev/null +++ b/samples/bpf/test_lwt_bpf.c @@ -0,0 +1,253 @@ +/* Copyright (c) 2016 Thomas Graf <tgraf@tgraf.ch> + * + * 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. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + */ + +#include <stdint.h> +#include <stddef.h> +#include <linux/bpf.h> +#include <linux/ip.h> +#include <linux/in.h> +#include <linux/in6.h> +#include <linux/tcp.h> +#include <linux/udp.h> +#include <linux/icmpv6.h> +#include <linux/if_ether.h> +#include <bpf/bpf_helpers.h> +#include <string.h> + +# define printk(fmt, ...) \ + ({ \ + char ____fmt[] = fmt; \ + bpf_trace_printk(____fmt, sizeof(____fmt), \ + ##__VA_ARGS__); \ + }) + +#define CB_MAGIC 1234 + +/* Test: Pass all packets through */ +SEC("nop") +int do_nop(struct __sk_buff *skb) +{ + return BPF_OK; +} + +/* Test: Verify context information can be accessed */ +SEC("test_ctx") +int do_test_ctx(struct __sk_buff *skb) +{ + skb->cb[0] = CB_MAGIC; + printk("len %d hash %d protocol %d\n", skb->len, skb->hash, + skb->protocol); + printk("cb %d ingress_ifindex %d ifindex %d\n", skb->cb[0], + skb->ingress_ifindex, skb->ifindex); + + return BPF_OK; +} + +/* Test: Ensure skb->cb[] buffer is cleared */ +SEC("test_cb") +int do_test_cb(struct __sk_buff *skb) +{ + printk("cb0: %x cb1: %x cb2: %x\n", skb->cb[0], skb->cb[1], + skb->cb[2]); + printk("cb3: %x cb4: %x\n", skb->cb[3], skb->cb[4]); + + return BPF_OK; +} + +/* Test: Verify skb data can be read */ +SEC("test_data") +int do_test_data(struct __sk_buff *skb) +{ + void *data = (void *)(long)skb->data; + void *data_end = (void *)(long)skb->data_end; + struct iphdr *iph = data; + + if (data + sizeof(*iph) > data_end) { + printk("packet truncated\n"); + return BPF_DROP; + } + + printk("src: %x dst: %x\n", iph->saddr, iph->daddr); + + return BPF_OK; +} + +#define IP_CSUM_OFF offsetof(struct iphdr, check) +#define IP_DST_OFF offsetof(struct iphdr, daddr) +#define IP_SRC_OFF offsetof(struct iphdr, saddr) +#define IP_PROTO_OFF offsetof(struct iphdr, protocol) +#define TCP_CSUM_OFF offsetof(struct tcphdr, check) +#define UDP_CSUM_OFF offsetof(struct udphdr, check) +#define IS_PSEUDO 0x10 + +static inline int rewrite(struct __sk_buff *skb, uint32_t old_ip, + uint32_t new_ip, int rw_daddr) +{ + int ret, off = 0, flags = IS_PSEUDO; + uint8_t proto; + + ret = bpf_skb_load_bytes(skb, IP_PROTO_OFF, &proto, 1); + if (ret < 0) { + printk("bpf_l4_csum_replace failed: %d\n", ret); + return BPF_DROP; + } + + switch (proto) { + case IPPROTO_TCP: + off = TCP_CSUM_OFF; + break; + + case IPPROTO_UDP: + off = UDP_CSUM_OFF; + flags |= BPF_F_MARK_MANGLED_0; + break; + + case IPPROTO_ICMPV6: + off = offsetof(struct icmp6hdr, icmp6_cksum); + break; + } + + if (off) { + ret = bpf_l4_csum_replace(skb, off, old_ip, new_ip, + flags | sizeof(new_ip)); + if (ret < 0) { + printk("bpf_l4_csum_replace failed: %d\n"); + return BPF_DROP; + } + } + + ret = bpf_l3_csum_replace(skb, IP_CSUM_OFF, old_ip, new_ip, sizeof(new_ip)); + if (ret < 0) { + printk("bpf_l3_csum_replace failed: %d\n", ret); + return BPF_DROP; + } + + if (rw_daddr) + ret = bpf_skb_store_bytes(skb, IP_DST_OFF, &new_ip, sizeof(new_ip), 0); + else + ret = bpf_skb_store_bytes(skb, IP_SRC_OFF, &new_ip, sizeof(new_ip), 0); + + if (ret < 0) { + printk("bpf_skb_store_bytes() failed: %d\n", ret); + return BPF_DROP; + } + + return BPF_OK; +} + +/* Test: Verify skb data can be modified */ +SEC("test_rewrite") +int do_test_rewrite(struct __sk_buff *skb) +{ + uint32_t old_ip, new_ip = 0x3fea8c0; + int ret; + + ret = bpf_skb_load_bytes(skb, IP_DST_OFF, &old_ip, 4); + if (ret < 0) { + printk("bpf_skb_load_bytes failed: %d\n", ret); + return BPF_DROP; + } + + if (old_ip == 0x2fea8c0) { + printk("out: rewriting from %x to %x\n", old_ip, new_ip); + return rewrite(skb, old_ip, new_ip, 1); + } + + return BPF_OK; +} + +static inline int __do_push_ll_and_redirect(struct __sk_buff *skb) +{ + uint64_t smac = SRC_MAC, dmac = DST_MAC; + int ret, ifindex = DST_IFINDEX; + struct ethhdr ehdr; + + ret = bpf_skb_change_head(skb, 14, 0); + if (ret < 0) { + printk("skb_change_head() failed: %d\n", ret); + } + + ehdr.h_proto = __constant_htons(ETH_P_IP); + memcpy(&ehdr.h_source, &smac, 6); + memcpy(&ehdr.h_dest, &dmac, 6); + + ret = bpf_skb_store_bytes(skb, 0, &ehdr, sizeof(ehdr), 0); + if (ret < 0) { + printk("skb_store_bytes() failed: %d\n", ret); + return BPF_DROP; + } + + return bpf_redirect(ifindex, 0); +} + +SEC("push_ll_and_redirect_silent") +int do_push_ll_and_redirect_silent(struct __sk_buff *skb) +{ + return __do_push_ll_and_redirect(skb); +} + +SEC("push_ll_and_redirect") +int do_push_ll_and_redirect(struct __sk_buff *skb) +{ + int ret, ifindex = DST_IFINDEX; + + ret = __do_push_ll_and_redirect(skb); + if (ret >= 0) + printk("redirected to %d\n", ifindex); + + return ret; +} + +static inline void __fill_garbage(struct __sk_buff *skb) +{ + uint64_t f = 0xFFFFFFFFFFFFFFFF; + + bpf_skb_store_bytes(skb, 0, &f, sizeof(f), 0); + bpf_skb_store_bytes(skb, 8, &f, sizeof(f), 0); + bpf_skb_store_bytes(skb, 16, &f, sizeof(f), 0); + bpf_skb_store_bytes(skb, 24, &f, sizeof(f), 0); + bpf_skb_store_bytes(skb, 32, &f, sizeof(f), 0); + bpf_skb_store_bytes(skb, 40, &f, sizeof(f), 0); + bpf_skb_store_bytes(skb, 48, &f, sizeof(f), 0); + bpf_skb_store_bytes(skb, 56, &f, sizeof(f), 0); + bpf_skb_store_bytes(skb, 64, &f, sizeof(f), 0); + bpf_skb_store_bytes(skb, 72, &f, sizeof(f), 0); + bpf_skb_store_bytes(skb, 80, &f, sizeof(f), 0); + bpf_skb_store_bytes(skb, 88, &f, sizeof(f), 0); +} + +SEC("fill_garbage") +int do_fill_garbage(struct __sk_buff *skb) +{ + __fill_garbage(skb); + printk("Set initial 96 bytes of header to FF\n"); + return BPF_OK; +} + +SEC("fill_garbage_and_redirect") +int do_fill_garbage_and_redirect(struct __sk_buff *skb) +{ + int ifindex = DST_IFINDEX; + __fill_garbage(skb); + printk("redirected to %d\n", ifindex); + return bpf_redirect(ifindex, 0); +} + +/* Drop all packets */ +SEC("drop_all") +int do_drop_all(struct __sk_buff *skb) +{ + printk("dropping with: %d\n", BPF_DROP); + return BPF_DROP; +} + +char _license[] SEC("license") = "GPL"; |