diff options
Diffstat (limited to 'tools/testing/selftests/bpf/progs/test_pkt_access.c')
| -rw-r--r-- | tools/testing/selftests/bpf/progs/test_pkt_access.c | 150 |
1 files changed, 150 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/progs/test_pkt_access.c b/tools/testing/selftests/bpf/progs/test_pkt_access.c new file mode 100644 index 000000000..852051064 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_pkt_access.c @@ -0,0 +1,150 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* Copyright (c) 2017 Facebook + */ +#include <stddef.h> +#include <string.h> +#include <linux/bpf.h> +#include <linux/if_ether.h> +#include <linux/if_packet.h> +#include <linux/ip.h> +#include <linux/ipv6.h> +#include <linux/in.h> +#include <linux/tcp.h> +#include <linux/pkt_cls.h> +#include <bpf/bpf_helpers.h> +#include <bpf/bpf_endian.h> + +#define barrier() __asm__ __volatile__("": : :"memory") +int _version SEC("version") = 1; + +/* llvm will optimize both subprograms into exactly the same BPF assembly + * + * Disassembly of section .text: + * + * 0000000000000000 test_pkt_access_subprog1: + * ; return skb->len * 2; + * 0: 61 10 00 00 00 00 00 00 r0 = *(u32 *)(r1 + 0) + * 1: 64 00 00 00 01 00 00 00 w0 <<= 1 + * 2: 95 00 00 00 00 00 00 00 exit + * + * 0000000000000018 test_pkt_access_subprog2: + * ; return skb->len * val; + * 3: 61 10 00 00 00 00 00 00 r0 = *(u32 *)(r1 + 0) + * 4: 64 00 00 00 01 00 00 00 w0 <<= 1 + * 5: 95 00 00 00 00 00 00 00 exit + * + * Which makes it an interesting test for BTF-enabled verifier. + */ +static __attribute__ ((noinline)) +int test_pkt_access_subprog1(volatile struct __sk_buff *skb) +{ + return skb->len * 2; +} + +static __attribute__ ((noinline)) +int test_pkt_access_subprog2(int val, volatile struct __sk_buff *skb) +{ + return skb->len * val; +} + +#define MAX_STACK (512 - 2 * 32) + +__attribute__ ((noinline)) +int get_skb_len(struct __sk_buff *skb) +{ + volatile char buf[MAX_STACK] = {}; + + return skb->len; +} + +__attribute__ ((noinline)) +int get_constant(long val) +{ + return val - 122; +} + +int get_skb_ifindex(int, struct __sk_buff *skb, int); + +__attribute__ ((noinline)) +int test_pkt_access_subprog3(int val, struct __sk_buff *skb) +{ + return get_skb_len(skb) * get_skb_ifindex(val, skb, get_constant(123)); +} + +__attribute__ ((noinline)) +int get_skb_ifindex(int val, struct __sk_buff *skb, int var) +{ + volatile char buf[MAX_STACK] = {}; + + return skb->ifindex * val * var; +} + +__attribute__ ((noinline)) +int test_pkt_write_access_subprog(struct __sk_buff *skb, __u32 off) +{ + void *data = (void *)(long)skb->data; + void *data_end = (void *)(long)skb->data_end; + struct tcphdr *tcp = NULL; + + if (off > sizeof(struct ethhdr) + sizeof(struct ipv6hdr)) + return -1; + + tcp = data + off; + if (tcp + 1 > data_end) + return -1; + /* make modification to the packet data */ + tcp->check++; + return 0; +} + +SEC("classifier/test_pkt_access") +int test_pkt_access(struct __sk_buff *skb) +{ + void *data_end = (void *)(long)skb->data_end; + void *data = (void *)(long)skb->data; + struct ethhdr *eth = (struct ethhdr *)(data); + struct tcphdr *tcp = NULL; + __u8 proto = 255; + __u64 ihl_len; + + if (eth + 1 > data_end) + return TC_ACT_SHOT; + + if (eth->h_proto == bpf_htons(ETH_P_IP)) { + struct iphdr *iph = (struct iphdr *)(eth + 1); + + if (iph + 1 > data_end) + return TC_ACT_SHOT; + ihl_len = iph->ihl * 4; + proto = iph->protocol; + tcp = (struct tcphdr *)((void *)(iph) + ihl_len); + } else if (eth->h_proto == bpf_htons(ETH_P_IPV6)) { + struct ipv6hdr *ip6h = (struct ipv6hdr *)(eth + 1); + + if (ip6h + 1 > data_end) + return TC_ACT_SHOT; + ihl_len = sizeof(*ip6h); + proto = ip6h->nexthdr; + tcp = (struct tcphdr *)((void *)(ip6h) + ihl_len); + } + + if (test_pkt_access_subprog1(skb) != skb->len * 2) + return TC_ACT_SHOT; + if (test_pkt_access_subprog2(2, skb) != skb->len * 2) + return TC_ACT_SHOT; + if (test_pkt_access_subprog3(3, skb) != skb->len * 3 * skb->ifindex) + return TC_ACT_SHOT; + if (tcp) { + if (test_pkt_write_access_subprog(skb, (void *)tcp - data)) + return TC_ACT_SHOT; + if (((void *)(tcp) + 20) > data_end || proto != 6) + return TC_ACT_SHOT; + barrier(); /* to force ordering of checks */ + if (((void *)(tcp) + 18) > data_end) + return TC_ACT_SHOT; + if (tcp->urg_ptr == 123) + return TC_ACT_OK; + } + + return TC_ACT_UNSPEC; +} |