selftests/bpf: tests for using dynptrs to parse skb and xdp buffers

Test skb and xdp dynptr functionality in the following ways:

1) progs/test_cls_redirect_dynptr.c
   * Rewrite "progs/test_cls_redirect.c" test to use dynptrs to parse
     skb data

   * This is a great example of how dynptrs can be used to simplify a
     lot of the parsing logic for non-statically known values.

     When measuring the user + system time between the original version
     vs. using dynptrs, and averaging the time for 10 runs (using
     "time ./test_progs -t cls_redirect"):
         original version: 0.092 sec
         with dynptrs: 0.078 sec

2) progs/test_xdp_dynptr.c
   * Rewrite "progs/test_xdp.c" test to use dynptrs to parse xdp data

     When measuring the user + system time between the original version
     vs. using dynptrs, and averaging the time for 10 runs (using
     "time ./test_progs -t xdp_attach"):
         original version: 0.118 sec
         with dynptrs: 0.094 sec

3) progs/test_l4lb_noinline_dynptr.c
   * Rewrite "progs/test_l4lb_noinline.c" test to use dynptrs to parse
     skb data

     When measuring the user + system time between the original version
     vs. using dynptrs, and averaging the time for 10 runs (using
     "time ./test_progs -t l4lb_all"):
         original version: 0.062 sec
         with dynptrs: 0.081 sec

     For number of processed verifier instructions:
         original version: 6268 insns
         with dynptrs: 2588 insns

4) progs/test_parse_tcp_hdr_opt_dynptr.c
   * Add sample code for parsing tcp hdr opt lookup using dynptrs.
     This logic is lifted from a real-world use case of packet parsing
     in katran [0], a layer 4 load balancer. The original version
     "progs/test_parse_tcp_hdr_opt.c" (not using dynptrs) is included
     here as well, for comparison.

     When measuring the user + system time between the original version
     vs. using dynptrs, and averaging the time for 10 runs (using
     "time ./test_progs -t parse_tcp_hdr_opt"):
         original version: 0.031 sec
         with dynptrs: 0.045 sec

5) progs/dynptr_success.c
   * Add test case "test_skb_readonly" for testing attempts at writes
     on a prog type with read-only skb ctx.
   * Add "test_dynptr_skb_data" for testing that bpf_dynptr_data isn't
     supported for skb progs.

6) progs/dynptr_fail.c
   * Add test cases "skb_invalid_data_slice{1,2,3,4}" and
     "xdp_invalid_data_slice{1,2}" for testing that helpers that modify the
     underlying packet buffer automatically invalidate the associated
     data slice.
   * Add test cases "skb_invalid_ctx" and "xdp_invalid_ctx" for testing
     that prog types that do not support bpf_dynptr_from_skb/xdp don't
     have access to the API.
   * Add test case "dynptr_slice_var_len{1,2}" for testing that
     variable-sized len can't be passed in to bpf_dynptr_slice
   * Add test case "skb_invalid_slice_write" for testing that writes to a
     read-only data slice are rejected by the verifier.
   * Add test case "data_slice_out_of_bounds_skb" for testing that
     writes to an area outside the slice are rejected.
   * Add test case "invalid_slice_rdwr_rdonly" for testing that prog
     types that don't allow writes to packet data don't accept any calls
     to bpf_dynptr_slice_rdwr.

[0] https://github.com/facebookincubator/katran/blob/main/katran/lib/bpf/pckt_parsing.h

Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230301154953.641654-11-joannelkoong@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 93 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/parse_tcp_hdr_opt.c b/tools/testing/selftests/bpf/prog_tests/parse_tcp_hdr_opt.c
new file mode 100644
index 000000000000..daa952711d8f
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/parse_tcp_hdr_opt.c
@@ -0,0 +1,93 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <test_progs.h>
+#include <network_helpers.h>
+#include "test_parse_tcp_hdr_opt.skel.h"
+#include "test_parse_tcp_hdr_opt_dynptr.skel.h"
+#include "test_tcp_hdr_options.h"
+
+struct test_pkt {
+	struct ipv6_packet pk6_v6;
+	u8 options[16];
+} __packed;
+
+struct test_pkt pkt = {
+	.pk6_v6.eth.h_proto = __bpf_constant_htons(ETH_P_IPV6),
+	.pk6_v6.iph.nexthdr = IPPROTO_TCP,
+	.pk6_v6.iph.payload_len = __bpf_constant_htons(MAGIC_BYTES),
+	.pk6_v6.tcp.urg_ptr = 123,
+	.pk6_v6.tcp.doff = 9, /* 16 bytes of options */
+
+	.options = {
+		TCPOPT_MSS, 4, 0x05, 0xB4, TCPOPT_NOP, TCPOPT_NOP,
+		0, 6, 0xBB, 0xBB, 0xBB, 0xBB, TCPOPT_EOL
+	},
+};
+
+static void test_parse_opt(void)
+{
+	struct test_parse_tcp_hdr_opt *skel;
+	struct bpf_program *prog;
+	char buf[128];
+	int err;
+
+	LIBBPF_OPTS(bpf_test_run_opts, topts,
+		    .data_in = &pkt,
+		    .data_size_in = sizeof(pkt),
+		    .data_out = buf,
+		    .data_size_out = sizeof(buf),
+		    .repeat = 3,
+	);
+
+	skel = test_parse_tcp_hdr_opt__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "skel_open_and_load"))
+		return;
+
+	pkt.options[6] = skel->rodata->tcp_hdr_opt_kind_tpr;
+	prog = skel->progs.xdp_ingress_v6;
+
+	err = bpf_prog_test_run_opts(bpf_program__fd(prog), &topts);
+	ASSERT_OK(err, "ipv6 test_run");
+	ASSERT_EQ(topts.retval, XDP_PASS, "ipv6 test_run retval");
+	ASSERT_EQ(skel->bss->server_id, 0xBBBBBBBB, "server id");
+
+	test_parse_tcp_hdr_opt__destroy(skel);
+}
+
+static void test_parse_opt_dynptr(void)
+{
+	struct test_parse_tcp_hdr_opt_dynptr *skel;
+	struct bpf_program *prog;
+	char buf[128];
+	int err;
+
+	LIBBPF_OPTS(bpf_test_run_opts, topts,
+		    .data_in = &pkt,
+		    .data_size_in = sizeof(pkt),
+		    .data_out = buf,
+		    .data_size_out = sizeof(buf),
+		    .repeat = 3,
+	);
+
+	skel = test_parse_tcp_hdr_opt_dynptr__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "skel_open_and_load"))
+		return;
+
+	pkt.options[6] = skel->rodata->tcp_hdr_opt_kind_tpr;
+	prog = skel->progs.xdp_ingress_v6;
+
+	err = bpf_prog_test_run_opts(bpf_program__fd(prog), &topts);
+	ASSERT_OK(err, "ipv6 test_run");
+	ASSERT_EQ(topts.retval, XDP_PASS, "ipv6 test_run retval");
+	ASSERT_EQ(skel->bss->server_id, 0xBBBBBBBB, "server id");
+
+	test_parse_tcp_hdr_opt_dynptr__destroy(skel);
+}
+
+void test_parse_tcp_hdr_opt(void)
+{
+	if (test__start_subtest("parse_tcp_hdr_opt"))
+		test_parse_opt();
+	if (test__start_subtest("parse_tcp_hdr_opt_dynptr"))
+		test_parse_opt_dynptr();
+}