Commit bee4b7e6 authored by Toke Høiland-Jørgensen's avatar Toke Høiland-Jørgensen Committed by Alexei Starovoitov
Browse files

selftests: Add selftest for disallowing modify_return attachment to freplace 



This adds a selftest that ensures that modify_return tracing programs
cannot be attached to freplace programs. The security_ prefix is added to
the freplace program because that would otherwise let it pass the check for
modify_return.

Signed-off-by: default avatarToke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarAndrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/160138355713.48470.3811074984255709369.stgit@toke.dk
parent 17d3f386

tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c

+56 −0
Original line number Diff line number Diff line
@@ -232,6 +232,60 @@ static void test_func_replace_multi(void) 
				  prog_name, true, test_second_attach);

}



static void test_fmod_ret_freplace(void)

{

	struct bpf_object *freplace_obj = NULL, *pkt_obj, *fmod_obj = NULL;

	const char *freplace_name = "./freplace_get_constant.o";

	const char *fmod_ret_name = "./fmod_ret_freplace.o";

	DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts);

	const char *tgt_name = "./test_pkt_access.o";

	struct bpf_link *freplace_link = NULL;

	struct bpf_program *prog;

	__u32 duration = 0;

	int err, pkt_fd;



	err = bpf_prog_load(tgt_name, BPF_PROG_TYPE_UNSPEC,

			    &pkt_obj, &pkt_fd);

	/* the target prog should load fine */

	if (CHECK(err, "tgt_prog_load", "file %s err %d errno %d\n",

		  tgt_name, err, errno))

		return;

	opts.attach_prog_fd = pkt_fd;



	freplace_obj = bpf_object__open_file(freplace_name, &opts);

	if (CHECK(IS_ERR_OR_NULL(freplace_obj), "freplace_obj_open",

		  "failed to open %s: %ld\n", freplace_name,

		  PTR_ERR(freplace_obj)))

		goto out;



	err = bpf_object__load(freplace_obj);

	if (CHECK(err, "freplace_obj_load", "err %d\n", err))

		goto out;



	prog = bpf_program__next(NULL, freplace_obj);

	freplace_link = bpf_program__attach_trace(prog);

	if (CHECK(IS_ERR(freplace_link), "freplace_attach_trace", "failed to link\n"))

		goto out;



	opts.attach_prog_fd = bpf_program__fd(prog);

	fmod_obj = bpf_object__open_file(fmod_ret_name, &opts);

	if (CHECK(IS_ERR_OR_NULL(fmod_obj), "fmod_obj_open",

		  "failed to open %s: %ld\n", fmod_ret_name,

		  PTR_ERR(fmod_obj)))

		goto out;



	err = bpf_object__load(fmod_obj);

	if (CHECK(!err, "fmod_obj_load", "loading fmod_ret should fail\n"))

		goto out;



out:

	bpf_link__destroy(freplace_link);

	bpf_object__close(freplace_obj);

	bpf_object__close(fmod_obj);

	bpf_object__close(pkt_obj);

}





static void test_func_sockmap_update(void)

{

	const char *prog_name[] = {
@@ -314,4 +368,6 @@ void test_fexit_bpf2bpf(void) 
		test_func_map_prog_compatibility();

	if (test__start_subtest("func_replace_multi"))

		test_func_replace_multi();

	if (test__start_subtest("fmod_ret_freplace"))

		test_fmod_ret_freplace();

}

tools/testing/selftests/bpf/progs/fmod_ret_freplace.c

0 → 100644
+14 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

#include <linux/bpf.h>

#include <bpf/bpf_helpers.h>

#include <bpf/bpf_tracing.h>



volatile __u64 test_fmod_ret = 0;

SEC("fmod_ret/security_new_get_constant")

int BPF_PROG(fmod_ret_test, long val, int ret)

{

	test_fmod_ret = 1;

	return 120;

}



char _license[] SEC("license") = "GPL";

tools/testing/selftests/bpf/progs/freplace_get_constant.c

+1 −1
Original line number Diff line number Diff line
@@ -5,7 +5,7 @@ 


volatile __u64 test_get_constant = 0;

SEC("freplace/get_constant")

int new_get_constant(long val)

int security_new_get_constant(long val)

{

	if (val != 123)

		return 0;