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>

tools/testing/selftests/bpf/DENYLIST.s390x

@@ -4,6 +4,8 @@ bloom_filter_map                         # failed to find kernel BTF type ID of
 bpf_cookie                               # failed to open_and_load program: -524 (trampoline)
 bpf_loop                                 # attaches to __x64_sys_nanosleep
 cgrp_local_storage                       # prog_attach unexpected error: -524                                          (trampoline)
+dynptr/test_dynptr_skb_data
+dynptr/test_skb_readonly
 fexit_sleep                              # fexit_skel_load fexit skeleton failed                                       (trampoline)
 get_stack_raw_tp                         # user_stack corrupted user stack                                             (no backchain userspace)
 kprobe_multi_bench_attach                # bpf_program__attach_kprobe_multi_opts unexpected error: -95

tools/testing/selftests/bpf/bpf_kfuncs.h

@@ -0,0 +1,38 @@
+#ifndef __BPF_KFUNCS__
+#define __BPF_KFUNCS__
+
+/* Description
+ *  Initializes an skb-type dynptr
+ * Returns
+ *  Error code
+ */
+extern int bpf_dynptr_from_skb(struct __sk_buff *skb, __u64 flags,
+    struct bpf_dynptr *ptr__uninit) __ksym;
+
+/* Description
+ *  Initializes an xdp-type dynptr
+ * Returns
+ *  Error code
+ */
+extern int bpf_dynptr_from_xdp(struct xdp_md *xdp, __u64 flags,
+			       struct bpf_dynptr *ptr__uninit) __ksym;
+
+/* Description
+ *  Obtain a read-only pointer to the dynptr's data
+ * Returns
+ *  Either a direct pointer to the dynptr data or a pointer to the user-provided
+ *  buffer if unable to obtain a direct pointer
+ */
+extern void *bpf_dynptr_slice(const struct bpf_dynptr *ptr, __u32 offset,
+			      void *buffer, __u32 buffer__szk) __ksym;
+
+/* Description
+ *  Obtain a read-write pointer to the dynptr's data
+ * Returns
+ *  Either a direct pointer to the dynptr data or a pointer to the user-provided
+ *  buffer if unable to obtain a direct pointer
+ */
+extern void *bpf_dynptr_slice_rdwr(const struct bpf_dynptr *ptr, __u32 offset,
+			      void *buffer, __u32 buffer__szk) __ksym;
+
+#endif

tools/testing/selftests/bpf/prog_tests/cls_redirect.c

@@ -13,6 +13,7 @@
 
 #include "progs/test_cls_redirect.h"
 #include "test_cls_redirect.skel.h"
+#include "test_cls_redirect_dynptr.skel.h"
 #include "test_cls_redirect_subprogs.skel.h"
 
 #define ENCAP_IP INADDR_LOOPBACK
@@ -446,6 +447,28 @@ static void test_cls_redirect_common(struct bpf_program *prog)
 	close_fds((int *)conns, sizeof(conns) / sizeof(conns[0][0]));
 }
 
+static void test_cls_redirect_dynptr(void)
+{
+	struct test_cls_redirect_dynptr *skel;
+	int err;
+
+	skel = test_cls_redirect_dynptr__open();
+	if (!ASSERT_OK_PTR(skel, "skel_open"))
+		return;
+
+	skel->rodata->ENCAPSULATION_IP = htonl(ENCAP_IP);
+	skel->rodata->ENCAPSULATION_PORT = htons(ENCAP_PORT);
+
+	err = test_cls_redirect_dynptr__load(skel);
+	if (!ASSERT_OK(err, "skel_load"))
+		goto cleanup;
+
+	test_cls_redirect_common(skel->progs.cls_redirect);
+
+cleanup:
+	test_cls_redirect_dynptr__destroy(skel);
+}
+
 static void test_cls_redirect_inlined(void)
 {
 	struct test_cls_redirect *skel;
@@ -496,4 +519,6 @@ void test_cls_redirect(void)
 		test_cls_redirect_inlined();
 	if (test__start_subtest("cls_redirect_subprogs"))
 		test_cls_redirect_subprogs();
+	if (test__start_subtest("cls_redirect_dynptr"))
+		test_cls_redirect_dynptr();
 }

tools/testing/selftests/bpf/prog_tests/dynptr.c

@@ -2,44 +2,86 @@
 /* Copyright (c) 2022 Facebook */
 
 #include <test_progs.h>
+#include <network_helpers.h>
 #include "dynptr_fail.skel.h"
 #include "dynptr_success.skel.h"
 
-static const char * const success_tests[] = {
-	"test_read_write",
-	"test_data_slice",
-	"test_ringbuf",
+enum test_setup_type {
+	SETUP_SYSCALL_SLEEP,
+	SETUP_SKB_PROG,
 };
 
-static void verify_success(const char *prog_name)
+static struct {
+	const char *prog_name;
+	enum test_setup_type type;
+} success_tests[] = {
+	{"test_read_write", SETUP_SYSCALL_SLEEP},
+	{"test_dynptr_data", SETUP_SYSCALL_SLEEP},
+	{"test_ringbuf", SETUP_SYSCALL_SLEEP},
+	{"test_skb_readonly", SETUP_SKB_PROG},
+	{"test_dynptr_skb_data", SETUP_SKB_PROG},
+};
+
+static void verify_success(const char *prog_name, enum test_setup_type setup_type)
 {
 	struct dynptr_success *skel;
 	struct bpf_program *prog;
 	struct bpf_link *link;
+       int err;
 
 	skel = dynptr_success__open();
 	if (!ASSERT_OK_PTR(skel, "dynptr_success__open"))
 		return;
 
 	skel->bss->pid = getpid();
 
-	dynptr_success__load(skel);
-	if (!ASSERT_OK_PTR(skel, "dynptr_success__load"))
-		goto cleanup;
-
 	prog = bpf_object__find_program_by_name(skel->obj, prog_name);
 	if (!ASSERT_OK_PTR(prog, "bpf_object__find_program_by_name"))
 		goto cleanup;
 
-	link = bpf_program__attach(prog);
-	if (!ASSERT_OK_PTR(link, "bpf_program__attach"))
+       bpf_program__set_autoload(prog, true);
+
+	err = dynptr_success__load(skel);
+	if (!ASSERT_OK(err, "dynptr_success__load"))
 		goto cleanup;
 
-	usleep(1);
+	switch (setup_type) {
+	case SETUP_SYSCALL_SLEEP:
+		link = bpf_program__attach(prog);
+		if (!ASSERT_OK_PTR(link, "bpf_program__attach"))
+			goto cleanup;
 
-	ASSERT_EQ(skel->bss->err, 0, "err");
+		usleep(1);
+
+		bpf_link__destroy(link);
+		break;
+	case SETUP_SKB_PROG:
+	{
+		int prog_fd;
+		char buf[64];
+
+		LIBBPF_OPTS(bpf_test_run_opts, topts,
+			    .data_in = &pkt_v4,
+			    .data_size_in = sizeof(pkt_v4),
+			    .data_out = buf,
+			    .data_size_out = sizeof(buf),
+			    .repeat = 1,
+		);
 
-	bpf_link__destroy(link);
+		prog_fd = bpf_program__fd(prog);
+		if (!ASSERT_GE(prog_fd, 0, "prog_fd"))
+			goto cleanup;
+
+		err = bpf_prog_test_run_opts(prog_fd, &topts);
+
+		if (!ASSERT_OK(err, "test_run"))
+			goto cleanup;
+
+		break;
+	}
+	}
+
+	ASSERT_EQ(skel->bss->err, 0, "err");
 
 cleanup:
 	dynptr_success__destroy(skel);
@@ -50,10 +92,10 @@ void test_dynptr(void)
 	int i;
 
 	for (i = 0; i < ARRAY_SIZE(success_tests); i++) {
-		if (!test__start_subtest(success_tests[i]))
+		if (!test__start_subtest(success_tests[i].prog_name))
 			continue;
 
-		verify_success(success_tests[i]);
+		verify_success(success_tests[i].prog_name, success_tests[i].type);
 	}
 
 	RUN_TESTS(dynptr_fail);

tools/testing/selftests/bpf/prog_tests/l4lb_all.c

@@ -93,4 +93,6 @@ void test_l4lb_all(void)
 		test_l4lb("test_l4lb.bpf.o");
 	if (test__start_subtest("l4lb_noinline"))
 		test_l4lb("test_l4lb_noinline.bpf.o");
+	if (test__start_subtest("l4lb_noinline_dynptr"))
+		test_l4lb("test_l4lb_noinline_dynptr.bpf.o");
 }

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();
+}

tools/testing/selftests/bpf/prog_tests/xdp_attach.c

@@ -4,11 +4,10 @@
 #define IFINDEX_LO 1
 #define XDP_FLAGS_REPLACE		(1U << 4)
 
-void serial_test_xdp_attach(void)
+static void test_xdp_attach(const char *file)
 {
 	__u32 duration = 0, id1, id2, id0 = 0, len;
 	struct bpf_object *obj1, *obj2, *obj3;
-	const char *file = "./test_xdp.bpf.o";
 	struct bpf_prog_info info = {};
 	int err, fd1, fd2, fd3;
 	LIBBPF_OPTS(bpf_xdp_attach_opts, opts);
@@ -85,3 +84,11 @@ void serial_test_xdp_attach(void)
 out_1:
 	bpf_object__close(obj1);
 }
+
+void serial_test_xdp_attach(void)
+{
+	if (test__start_subtest("xdp_attach"))
+		test_xdp_attach("./test_xdp.bpf.o");
+	if (test__start_subtest("xdp_attach_dynptr"))
+		test_xdp_attach("./test_xdp_dynptr.bpf.o");
+}