diff options
| -rw-r--r-- | tools/testing/selftests/bpf/Makefile | 4 | ||||
| -rwxr-xr-x | tools/testing/selftests/bpf/generate_udp_fragments.py | 90 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/ip_check_defrag_frags.h | 57 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/prog_tests/ip_check_defrag.c | 283 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/progs/ip_check_defrag.c | 104 |
5 files changed, 536 insertions, 2 deletions
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile index 73a6ca80fa16..e4e1e6492268 100644 --- a/tools/testing/selftests/bpf/Makefile +++ b/tools/testing/selftests/bpf/Makefile @@ -579,8 +579,8 @@ TRUNNER_EXTRA_SOURCES := test_progs.c cgroup_helpers.c trace_helpers.c \ network_helpers.c testing_helpers.c \ btf_helpers.c flow_dissector_load.h \ cap_helpers.c test_loader.c xsk.c disasm.c \ - json_writer.c unpriv_helpers.c - + json_writer.c unpriv_helpers.c \ + ip_check_defrag_frags.h TRUNNER_EXTRA_FILES := $(OUTPUT)/urandom_read $(OUTPUT)/bpf_testmod.ko \ $(OUTPUT)/liburandom_read.so \ $(OUTPUT)/xdp_synproxy \ diff --git a/tools/testing/selftests/bpf/generate_udp_fragments.py b/tools/testing/selftests/bpf/generate_udp_fragments.py new file mode 100755 index 000000000000..2b8a1187991c --- /dev/null +++ b/tools/testing/selftests/bpf/generate_udp_fragments.py @@ -0,0 +1,90 @@ +#!/bin/env python3 +# SPDX-License-Identifier: GPL-2.0 + +""" +This script helps generate fragmented UDP packets. + +While it is technically possible to dynamically generate +fragmented packets in C, it is much harder to read and write +said code. `scapy` is relatively industry standard and really +easy to read / write. + +So we choose to write this script that generates a valid C +header. Rerun script and commit generated file after any +modifications. +""" + +import argparse +import os + +from scapy.all import * + + +# These constants must stay in sync with `ip_check_defrag.c` +VETH1_ADDR = "172.16.1.200" +VETH0_ADDR6 = "fc00::100" +VETH1_ADDR6 = "fc00::200" +CLIENT_PORT = 48878 +SERVER_PORT = 48879 +MAGIC_MESSAGE = "THIS IS THE ORIGINAL MESSAGE, PLEASE REASSEMBLE ME" + + +def print_header(f): + f.write("// SPDX-License-Identifier: GPL-2.0\n") + f.write("/* DO NOT EDIT -- this file is generated */\n") + f.write("\n") + f.write("#ifndef _IP_CHECK_DEFRAG_FRAGS_H\n") + f.write("#define _IP_CHECK_DEFRAG_FRAGS_H\n") + f.write("\n") + f.write("#include <stdint.h>\n") + f.write("\n") + + +def print_frags(f, frags, v6): + for idx, frag in enumerate(frags): + # 10 bytes per line to keep width in check + chunks = [frag[i : i + 10] for i in range(0, len(frag), 10)] + chunks_fmted = [", ".join([str(hex(b)) for b in chunk]) for chunk in chunks] + suffix = "6" if v6 else "" + + f.write(f"static uint8_t frag{suffix}_{idx}[] = {{\n") + for chunk in chunks_fmted: + f.write(f"\t{chunk},\n") + f.write(f"}};\n") + + +def print_trailer(f): + f.write("\n") + f.write("#endif /* _IP_CHECK_DEFRAG_FRAGS_H */\n") + + +def main(f): + # srcip of 0 is filled in by IP_HDRINCL + sip = "0.0.0.0" + sip6 = VETH0_ADDR6 + dip = VETH1_ADDR + dip6 = VETH1_ADDR6 + sport = CLIENT_PORT + dport = SERVER_PORT + payload = MAGIC_MESSAGE.encode() + + # Disable UDPv4 checksums to keep code simpler + pkt = IP(src=sip,dst=dip) / UDP(sport=sport,dport=dport,chksum=0) / Raw(load=payload) + # UDPv6 requires a checksum + # Also pin the ipv6 fragment header ID, otherwise it's a random value + pkt6 = IPv6(src=sip6,dst=dip6) / IPv6ExtHdrFragment(id=0xBEEF) / UDP(sport=sport,dport=dport) / Raw(load=payload) + + frags = [f.build() for f in pkt.fragment(24)] + frags6 = [f.build() for f in fragment6(pkt6, 72)] + + print_header(f) + print_frags(f, frags, False) + print_frags(f, frags6, True) + print_trailer(f) + + +if __name__ == "__main__": + dir = os.path.dirname(os.path.realpath(__file__)) + header = f"{dir}/ip_check_defrag_frags.h" + with open(header, "w") as f: + main(f) diff --git a/tools/testing/selftests/bpf/ip_check_defrag_frags.h b/tools/testing/selftests/bpf/ip_check_defrag_frags.h new file mode 100644 index 000000000000..70ab7e9fa22b --- /dev/null +++ b/tools/testing/selftests/bpf/ip_check_defrag_frags.h @@ -0,0 +1,57 @@ +// SPDX-License-Identifier: GPL-2.0 +/* DO NOT EDIT -- this file is generated */ + +#ifndef _IP_CHECK_DEFRAG_FRAGS_H +#define _IP_CHECK_DEFRAG_FRAGS_H + +#include <stdint.h> + +static uint8_t frag_0[] = { + 0x45, 0x0, 0x0, 0x2c, 0x0, 0x1, 0x20, 0x0, 0x40, 0x11, + 0xac, 0xe8, 0x0, 0x0, 0x0, 0x0, 0xac, 0x10, 0x1, 0xc8, + 0xbe, 0xee, 0xbe, 0xef, 0x0, 0x3a, 0x0, 0x0, 0x54, 0x48, + 0x49, 0x53, 0x20, 0x49, 0x53, 0x20, 0x54, 0x48, 0x45, 0x20, + 0x4f, 0x52, 0x49, 0x47, +}; +static uint8_t frag_1[] = { + 0x45, 0x0, 0x0, 0x2c, 0x0, 0x1, 0x20, 0x3, 0x40, 0x11, + 0xac, 0xe5, 0x0, 0x0, 0x0, 0x0, 0xac, 0x10, 0x1, 0xc8, + 0x49, 0x4e, 0x41, 0x4c, 0x20, 0x4d, 0x45, 0x53, 0x53, 0x41, + 0x47, 0x45, 0x2c, 0x20, 0x50, 0x4c, 0x45, 0x41, 0x53, 0x45, + 0x20, 0x52, 0x45, 0x41, +}; +static uint8_t frag_2[] = { + 0x45, 0x0, 0x0, 0x1e, 0x0, 0x1, 0x0, 0x6, 0x40, 0x11, + 0xcc, 0xf0, 0x0, 0x0, 0x0, 0x0, 0xac, 0x10, 0x1, 0xc8, + 0x53, 0x53, 0x45, 0x4d, 0x42, 0x4c, 0x45, 0x20, 0x4d, 0x45, +}; +static uint8_t frag6_0[] = { + 0x60, 0x0, 0x0, 0x0, 0x0, 0x20, 0x2c, 0x40, 0xfc, 0x0, + 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, + 0x0, 0x0, 0x1, 0x0, 0xfc, 0x0, 0x0, 0x0, 0x0, 0x0, + 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x2, 0x0, + 0x11, 0x0, 0x0, 0x1, 0x0, 0x0, 0xbe, 0xef, 0xbe, 0xee, + 0xbe, 0xef, 0x0, 0x3a, 0xd0, 0xf8, 0x54, 0x48, 0x49, 0x53, + 0x20, 0x49, 0x53, 0x20, 0x54, 0x48, 0x45, 0x20, 0x4f, 0x52, + 0x49, 0x47, +}; +static uint8_t frag6_1[] = { + 0x60, 0x0, 0x0, 0x0, 0x0, 0x20, 0x2c, 0x40, 0xfc, 0x0, + 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, + 0x0, 0x0, 0x1, 0x0, 0xfc, 0x0, 0x0, 0x0, 0x0, 0x0, + 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x2, 0x0, + 0x11, 0x0, 0x0, 0x19, 0x0, 0x0, 0xbe, 0xef, 0x49, 0x4e, + 0x41, 0x4c, 0x20, 0x4d, 0x45, 0x53, 0x53, 0x41, 0x47, 0x45, + 0x2c, 0x20, 0x50, 0x4c, 0x45, 0x41, 0x53, 0x45, 0x20, 0x52, + 0x45, 0x41, +}; +static uint8_t frag6_2[] = { + 0x60, 0x0, 0x0, 0x0, 0x0, 0x12, 0x2c, 0x40, 0xfc, 0x0, + 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, + 0x0, 0x0, 0x1, 0x0, 0xfc, 0x0, 0x0, 0x0, 0x0, 0x0, + 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x2, 0x0, + 0x11, 0x0, 0x0, 0x30, 0x0, 0x0, 0xbe, 0xef, 0x53, 0x53, + 0x45, 0x4d, 0x42, 0x4c, 0x45, 0x20, 0x4d, 0x45, +}; + +#endif /* _IP_CHECK_DEFRAG_FRAGS_H */ diff --git a/tools/testing/selftests/bpf/prog_tests/ip_check_defrag.c b/tools/testing/selftests/bpf/prog_tests/ip_check_defrag.c new file mode 100644 index 000000000000..57c814f5f6a7 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/ip_check_defrag.c @@ -0,0 +1,283 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <test_progs.h> +#include <net/if.h> +#include <linux/netfilter.h> +#include <network_helpers.h> +#include "ip_check_defrag.skel.h" +#include "ip_check_defrag_frags.h" + +/* + * This selftest spins up a client and an echo server, each in their own + * network namespace. The client will send a fragmented message to the server. + * The prog attached to the server will shoot down any fragments. Thus, if + * the server is able to correctly echo back the message to the client, we will + * have verified that netfilter is reassembling packets for us. + * + * Topology: + * ========= + * NS0 | NS1 + * | + * client | server + * ---------- | ---------- + * | veth0 | --------- | veth1 | + * ---------- peer ---------- + * | + * | with bpf + */ + +#define NS0 "defrag_ns0" +#define NS1 "defrag_ns1" +#define VETH0 "veth0" +#define VETH1 "veth1" +#define VETH0_ADDR "172.16.1.100" +#define VETH0_ADDR6 "fc00::100" +/* The following constants must stay in sync with `generate_udp_fragments.py` */ +#define VETH1_ADDR "172.16.1.200" +#define VETH1_ADDR6 "fc00::200" +#define CLIENT_PORT 48878 +#define SERVER_PORT 48879 +#define MAGIC_MESSAGE "THIS IS THE ORIGINAL MESSAGE, PLEASE REASSEMBLE ME" + +static int setup_topology(bool ipv6) +{ + bool up; + int i; + + SYS(fail, "ip netns add " NS0); + SYS(fail, "ip netns add " NS1); + SYS(fail, "ip link add " VETH0 " netns " NS0 " type veth peer name " VETH1 " netns " NS1); + if (ipv6) { + SYS(fail, "ip -6 -net " NS0 " addr add " VETH0_ADDR6 "/64 dev " VETH0 " nodad"); + SYS(fail, "ip -6 -net " NS1 " addr add " VETH1_ADDR6 "/64 dev " VETH1 " nodad"); + } else { + SYS(fail, "ip -net " NS0 " addr add " VETH0_ADDR "/24 dev " VETH0); + SYS(fail, "ip -net " NS1 " addr add " VETH1_ADDR "/24 dev " VETH1); + } + SYS(fail, "ip -net " NS0 " link set dev " VETH0 " up"); + SYS(fail, "ip -net " NS1 " link set dev " VETH1 " up"); + + /* Wait for up to 5s for links to come up */ + for (i = 0; i < 5; ++i) { + if (ipv6) + up = !system("ip netns exec " NS0 " ping -6 -c 1 -W 1 " VETH1_ADDR6 " &>/dev/null"); + else + up = !system("ip netns exec " NS0 " ping -c 1 -W 1 " VETH1_ADDR " &>/dev/null"); + + if (up) + break; + } + + return 0; +fail: + return -1; +} + +static void cleanup_topology(void) +{ + SYS_NOFAIL("test -f /var/run/netns/" NS0 " && ip netns delete " NS0); + SYS_NOFAIL("test -f /var/run/netns/" NS1 " && ip netns delete " NS1); +} + +static int attach(struct ip_check_defrag *skel, bool ipv6) +{ + LIBBPF_OPTS(bpf_netfilter_opts, opts, + .pf = ipv6 ? NFPROTO_IPV6 : NFPROTO_IPV4, + .priority = 42, + .flags = BPF_F_NETFILTER_IP_DEFRAG); + struct nstoken *nstoken; + int err = -1; + + nstoken = open_netns(NS1); + + skel->links.defrag = bpf_program__attach_netfilter(skel->progs.defrag, &opts); + if (!ASSERT_OK_PTR(skel->links.defrag, "program attach")) + goto out; + + err = 0; +out: + close_netns(nstoken); + return err; +} + +static int send_frags(int client) +{ + struct sockaddr_storage saddr; + struct sockaddr *saddr_p; + socklen_t saddr_len; + int err; + + saddr_p = (struct sockaddr *)&saddr; + err = make_sockaddr(AF_INET, VETH1_ADDR, SERVER_PORT, &saddr, &saddr_len); + if (!ASSERT_OK(err, "make_sockaddr")) + return -1; + + err = sendto(client, frag_0, sizeof(frag_0), 0, saddr_p, saddr_len); + if (!ASSERT_GE(err, 0, "sendto frag_0")) + return -1; + + err = sendto(client, frag_1, sizeof(frag_1), 0, saddr_p, saddr_len); + if (!ASSERT_GE(err, 0, "sendto frag_1")) + return -1; + + err = sendto(client, frag_2, sizeof(frag_2), 0, saddr_p, saddr_len); + if (!ASSERT_GE(err, 0, "sendto frag_2")) + return -1; + + return 0; +} + +static int send_frags6(int client) +{ + struct sockaddr_storage saddr; + struct sockaddr *saddr_p; + socklen_t saddr_len; + int err; + + saddr_p = (struct sockaddr *)&saddr; + /* Port needs to be set to 0 for raw ipv6 socket for some reason */ + err = make_sockaddr(AF_INET6, VETH1_ADDR6, 0, &saddr, &saddr_len); + if (!ASSERT_OK(err, "make_sockaddr")) + return -1; + + err = sendto(client, frag6_0, sizeof(frag6_0), 0, saddr_p, saddr_len); + if (!ASSERT_GE(err, 0, "sendto frag6_0")) + return -1; + + err = sendto(client, frag6_1, sizeof(frag6_1), 0, saddr_p, saddr_len); + if (!ASSERT_GE(err, 0, "sendto frag6_1")) + return -1; + + err = sendto(client, frag6_2, sizeof(frag6_2), 0, saddr_p, saddr_len); + if (!ASSERT_GE(err, 0, "sendto frag6_2")) + return -1; + + return 0; +} + +void test_bpf_ip_check_defrag_ok(bool ipv6) +{ + struct network_helper_opts rx_opts = { + .timeout_ms = 1000, + .noconnect = true, + }; + struct network_helper_opts tx_ops = { + .timeout_ms = 1000, + .type = SOCK_RAW, + .proto = IPPROTO_RAW, + .noconnect = true, + }; + struct sockaddr_storage caddr; + struct ip_check_defrag *skel; + struct nstoken *nstoken; + int client_tx_fd = -1; + int client_rx_fd = -1; + socklen_t caddr_len; + int srv_fd = -1; + char buf[1024]; + int len, err; + + skel = ip_check_defrag__open_and_load(); + if (!ASSERT_OK_PTR(skel, "skel_open")) + return; + + if (!ASSERT_OK(setup_topology(ipv6), "setup_topology")) + goto out; + + if (!ASSERT_OK(attach(skel, ipv6), "attach")) + goto out; + + /* Start server in ns1 */ + nstoken = open_netns(NS1); + if (!ASSERT_OK_PTR(nstoken, "setns ns1")) + goto out; + srv_fd = start_server(ipv6 ? AF_INET6 : AF_INET, SOCK_DGRAM, NULL, SERVER_PORT, 0); + close_netns(nstoken); + if (!ASSERT_GE(srv_fd, 0, "start_server")) + goto out; + + /* Open tx raw socket in ns0 */ + nstoken = open_netns(NS0); + if (!ASSERT_OK_PTR(nstoken, "setns ns0")) + goto out; + client_tx_fd = connect_to_fd_opts(srv_fd, &tx_ops); + close_netns(nstoken); + if (!ASSERT_GE(client_tx_fd, 0, "connect_to_fd_opts")) + goto out; + + /* Open rx socket in ns0 */ + nstoken = open_netns(NS0); + if (!ASSERT_OK_PTR(nstoken, "setns ns0")) + goto out; + client_rx_fd = connect_to_fd_opts(srv_fd, &rx_opts); + close_netns(nstoken); + if (!ASSERT_GE(client_rx_fd, 0, "connect_to_fd_opts")) + goto out; + + /* Bind rx socket to a premeditated port */ + memset(&caddr, 0, sizeof(caddr)); + nstoken = open_netns(NS0); + if (!ASSERT_OK_PTR(nstoken, "setns ns0")) + goto out; + if (ipv6) { + struct sockaddr_in6 *c = (struct sockaddr_in6 *)&caddr; + + c->sin6_family = AF_INET6; + inet_pton(AF_INET6, VETH0_ADDR6, &c->sin6_addr); + c->sin6_port = htons(CLIENT_PORT); + err = bind(client_rx_fd, (struct sockaddr *)c, sizeof(*c)); + } else { + struct sockaddr_in *c = (struct sockaddr_in *)&caddr; + + c->sin_family = AF_INET; + inet_pton(AF_INET, VETH0_ADDR, &c->sin_addr); + c->sin_port = htons(CLIENT_PORT); + err = bind(client_rx_fd, (struct sockaddr *)c, sizeof(*c)); + } + close_netns(nstoken); + if (!ASSERT_OK(err, "bind")) + goto out; + + /* Send message in fragments */ + if (ipv6) { + if (!ASSERT_OK(send_frags6(client_tx_fd), "send_frags6")) + goto out; + } else { + if (!ASSERT_OK(send_frags(client_tx_fd), "send_frags")) + goto out; + } + + if (!ASSERT_EQ(skel->bss->shootdowns, 0, "shootdowns")) + goto out; + + /* Receive reassembled msg on server and echo back to client */ + caddr_len = sizeof(caddr); + len = recvfrom(srv_fd, buf, sizeof(buf), 0, (struct sockaddr *)&caddr, &caddr_len); + if (!ASSERT_GE(len, 0, "server recvfrom")) + goto out; + len = sendto(srv_fd, buf, len, 0, (struct sockaddr *)&caddr, caddr_len); + if (!ASSERT_GE(len, 0, "server sendto")) + goto out; + + /* Expect reassembed message to be echoed back */ + len = recvfrom(client_rx_fd, buf, sizeof(buf), 0, NULL, NULL); + if (!ASSERT_EQ(len, sizeof(MAGIC_MESSAGE) - 1, "client short read")) + goto out; + +out: + if (client_rx_fd != -1) + close(client_rx_fd); + if (client_tx_fd != -1) + close(client_tx_fd); + if (srv_fd != -1) + close(srv_fd); + cleanup_topology(); + ip_check_defrag__destroy(skel); +} + +void test_bpf_ip_check_defrag(void) +{ + if (test__start_subtest("v4")) + test_bpf_ip_check_defrag_ok(false); + if (test__start_subtest("v6")) + test_bpf_ip_check_defrag_ok(true); +} diff --git a/tools/testing/selftests/bpf/progs/ip_check_defrag.c b/tools/testing/selftests/bpf/progs/ip_check_defrag.c new file mode 100644 index 000000000000..1c2b6c1616b0 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/ip_check_defrag.c @@ -0,0 +1,104 @@ +// SPDX-License-Identifier: GPL-2.0-only +#include "vmlinux.h" +#include <bpf/bpf_helpers.h> +#include <bpf/bpf_endian.h> +#include "bpf_tracing_net.h" + +#define NF_DROP 0 +#define NF_ACCEPT 1 +#define ETH_P_IP 0x0800 +#define ETH_P_IPV6 0x86DD +#define IP_MF 0x2000 +#define IP_OFFSET 0x1FFF +#define NEXTHDR_FRAGMENT 44 + +extern int bpf_dynptr_from_skb(struct sk_buff *skb, __u64 flags, + struct bpf_dynptr *ptr__uninit) __ksym; +extern void *bpf_dynptr_slice(const struct bpf_dynptr *ptr, uint32_t offset, + void *buffer, uint32_t buffer__sz) __ksym; + +volatile int shootdowns = 0; + +static bool is_frag_v4(struct iphdr *iph) +{ + int offset; + int flags; + + offset = bpf_ntohs(iph->frag_off); + flags = offset & ~IP_OFFSET; + offset &= IP_OFFSET; + offset <<= 3; + + return (flags & IP_MF) || offset; +} + +static bool is_frag_v6(struct ipv6hdr *ip6h) +{ + /* Simplifying assumption that there are no extension headers + * between fixed header and fragmentation header. This assumption + * is only valid in this test case. It saves us the hassle of + * searching all potential extension headers. + */ + return ip6h->nexthdr == NEXTHDR_FRAGMENT; +} + +static int handle_v4(struct sk_buff *skb) +{ + struct bpf_dynptr ptr; + u8 iph_buf[20] = {}; + struct iphdr *iph; + + if (bpf_dynptr_from_skb(skb, 0, &ptr)) + return NF_DROP; + + iph = bpf_dynptr_slice(&ptr, 0, iph_buf, sizeof(iph_buf)); + if (!iph) + return NF_DROP; + + /* Shootdown any frags */ + if (is_frag_v4(iph)) { + shootdowns++; + return NF_DROP; + } + + return NF_ACCEPT; +} + +static int handle_v6(struct sk_buff *skb) +{ + struct bpf_dynptr ptr; + struct ipv6hdr *ip6h; + u8 ip6h_buf[40] = {}; + + if (bpf_dynptr_from_skb(skb, 0, &ptr)) + return NF_DROP; + + ip6h = bpf_dynptr_slice(&ptr, 0, ip6h_buf, sizeof(ip6h_buf)); + if (!ip6h) + return NF_DROP; + + /* Shootdown any frags */ + if (is_frag_v6(ip6h)) { + shootdowns++; + return NF_DROP; + } + + return NF_ACCEPT; +} + +SEC("netfilter") +int defrag(struct bpf_nf_ctx *ctx) +{ + struct sk_buff *skb = ctx->skb; + + switch (bpf_ntohs(skb->protocol)) { + case ETH_P_IP: + return handle_v4(skb); + case ETH_P_IPV6: + return handle_v6(skb); + default: + return NF_ACCEPT; + } +} + +char _license[] SEC("license") = "GPL"; |