diff options
Diffstat (limited to 'tools/testing/selftests/bpf/progs/test_sk_assign.c')
| -rw-r--r-- | tools/testing/selftests/bpf/progs/test_sk_assign.c | 204 |
1 files changed, 204 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/progs/test_sk_assign.c b/tools/testing/selftests/bpf/progs/test_sk_assign.c new file mode 100644 index 000000000000..8f530843b4da --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_sk_assign.c @@ -0,0 +1,204 @@ +// SPDX-License-Identifier: GPL-2.0 +// Copyright (c) 2019 Cloudflare Ltd. +// Copyright (c) 2020 Isovalent, Inc. + +#include <stddef.h> +#include <stdbool.h> +#include <string.h> +#include <linux/bpf.h> +#include <linux/if_ether.h> +#include <linux/in.h> +#include <linux/ip.h> +#include <linux/ipv6.h> +#include <linux/pkt_cls.h> +#include <linux/tcp.h> +#include <sys/socket.h> +#include <bpf/bpf_helpers.h> +#include <bpf/bpf_endian.h> + +int _version SEC("version") = 1; +char _license[] SEC("license") = "GPL"; + +/* Fill 'tuple' with L3 info, and attempt to find L4. On fail, return NULL. */ +static inline struct bpf_sock_tuple * +get_tuple(struct __sk_buff *skb, bool *ipv4, bool *tcp) +{ + void *data_end = (void *)(long)skb->data_end; + void *data = (void *)(long)skb->data; + struct bpf_sock_tuple *result; + struct ethhdr *eth; + __u64 tuple_len; + __u8 proto = 0; + __u64 ihl_len; + + eth = (struct ethhdr *)(data); + if (eth + 1 > data_end) + return NULL; + + if (eth->h_proto == bpf_htons(ETH_P_IP)) { + struct iphdr *iph = (struct iphdr *)(data + sizeof(*eth)); + + if (iph + 1 > data_end) + return NULL; + if (iph->ihl != 5) + /* Options are not supported */ + return NULL; + ihl_len = iph->ihl * 4; + proto = iph->protocol; + *ipv4 = true; + result = (struct bpf_sock_tuple *)&iph->saddr; + } else if (eth->h_proto == bpf_htons(ETH_P_IPV6)) { + struct ipv6hdr *ip6h = (struct ipv6hdr *)(data + sizeof(*eth)); + + if (ip6h + 1 > data_end) + return NULL; + ihl_len = sizeof(*ip6h); + proto = ip6h->nexthdr; + *ipv4 = false; + result = (struct bpf_sock_tuple *)&ip6h->saddr; + } else { + return (struct bpf_sock_tuple *)data; + } + + if (proto != IPPROTO_TCP && proto != IPPROTO_UDP) + return NULL; + + *tcp = (proto == IPPROTO_TCP); + return result; +} + +static inline int +handle_udp(struct __sk_buff *skb, struct bpf_sock_tuple *tuple, bool ipv4) +{ + struct bpf_sock_tuple ln = {0}; + struct bpf_sock *sk; + size_t tuple_len; + int ret; + + tuple_len = ipv4 ? sizeof(tuple->ipv4) : sizeof(tuple->ipv6); + if ((void *)tuple + tuple_len > (void *)(long)skb->data_end) + return TC_ACT_SHOT; + + sk = bpf_sk_lookup_udp(skb, tuple, tuple_len, BPF_F_CURRENT_NETNS, 0); + if (sk) + goto assign; + + if (ipv4) { + if (tuple->ipv4.dport != bpf_htons(4321)) + return TC_ACT_OK; + + ln.ipv4.daddr = bpf_htonl(0x7f000001); + ln.ipv4.dport = bpf_htons(1234); + + sk = bpf_sk_lookup_udp(skb, &ln, sizeof(ln.ipv4), + BPF_F_CURRENT_NETNS, 0); + } else { + if (tuple->ipv6.dport != bpf_htons(4321)) + return TC_ACT_OK; + + /* Upper parts of daddr are already zero. */ + ln.ipv6.daddr[3] = bpf_htonl(0x1); + ln.ipv6.dport = bpf_htons(1234); + + sk = bpf_sk_lookup_udp(skb, &ln, sizeof(ln.ipv6), + BPF_F_CURRENT_NETNS, 0); + } + + /* workaround: We can't do a single socket lookup here, because then + * the compiler will likely spill tuple_len to the stack. This makes it + * lose all bounds information in the verifier, which then rejects the + * call as unsafe. + */ + if (!sk) + return TC_ACT_SHOT; + +assign: + ret = bpf_sk_assign(skb, sk, 0); + bpf_sk_release(sk); + return ret; +} + +static inline int +handle_tcp(struct __sk_buff *skb, struct bpf_sock_tuple *tuple, bool ipv4) +{ + struct bpf_sock_tuple ln = {0}; + struct bpf_sock *sk; + size_t tuple_len; + int ret; + + tuple_len = ipv4 ? sizeof(tuple->ipv4) : sizeof(tuple->ipv6); + if ((void *)tuple + tuple_len > (void *)(long)skb->data_end) + return TC_ACT_SHOT; + + sk = bpf_skc_lookup_tcp(skb, tuple, tuple_len, BPF_F_CURRENT_NETNS, 0); + if (sk) { + if (sk->state != BPF_TCP_LISTEN) + goto assign; + bpf_sk_release(sk); + } + + if (ipv4) { + if (tuple->ipv4.dport != bpf_htons(4321)) + return TC_ACT_OK; + + ln.ipv4.daddr = bpf_htonl(0x7f000001); + ln.ipv4.dport = bpf_htons(1234); + + sk = bpf_skc_lookup_tcp(skb, &ln, sizeof(ln.ipv4), + BPF_F_CURRENT_NETNS, 0); + } else { + if (tuple->ipv6.dport != bpf_htons(4321)) + return TC_ACT_OK; + + /* Upper parts of daddr are already zero. */ + ln.ipv6.daddr[3] = bpf_htonl(0x1); + ln.ipv6.dport = bpf_htons(1234); + + sk = bpf_skc_lookup_tcp(skb, &ln, sizeof(ln.ipv6), + BPF_F_CURRENT_NETNS, 0); + } + + /* workaround: We can't do a single socket lookup here, because then + * the compiler will likely spill tuple_len to the stack. This makes it + * lose all bounds information in the verifier, which then rejects the + * call as unsafe. + */ + if (!sk) + return TC_ACT_SHOT; + + if (sk->state != BPF_TCP_LISTEN) { + bpf_sk_release(sk); + return TC_ACT_SHOT; + } + +assign: + ret = bpf_sk_assign(skb, sk, 0); + bpf_sk_release(sk); + return ret; +} + +SEC("classifier/sk_assign_test") +int bpf_sk_assign_test(struct __sk_buff *skb) +{ + struct bpf_sock_tuple *tuple, ln = {0}; + bool ipv4 = false; + bool tcp = false; + int tuple_len; + int ret = 0; + + tuple = get_tuple(skb, &ipv4, &tcp); + if (!tuple) + return TC_ACT_SHOT; + + /* Note that the verifier socket return type for bpf_skc_lookup_tcp() + * differs from bpf_sk_lookup_udp(), so even though the C-level type is + * the same here, if we try to share the implementations they will + * fail to verify because we're crossing pointer types. + */ + if (tcp) + ret = handle_tcp(skb, tuple, ipv4); + else + ret = handle_udp(skb, tuple, ipv4); + + return ret == 0 ? TC_ACT_OK : TC_ACT_SHOT; +} |