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selftests: Add selftest for disallowing modify_return attachment to freplace

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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: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/160138355713.48470.3811074984255709369.stgit@toke.dk
This commit is contained in:
Toke Høiland-Jørgensen 2020-09-29 14:45:57 +02:00 committed by Alexei Starovoitov
parent 17d3f38675
commit bee4b7e626
3 changed files with 71 additions and 1 deletions
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56
tools/testing/selftests/bpf/prog_tests/fexit_bpf2bpf.c
View File

@ -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();
}

14
tools/testing/selftests/bpf/progs/fmod_ret_freplace.c Normal file
View File

@ -0,0 +1,14 @@
// 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";

2
tools/testing/selftests/bpf/progs/freplace_get_constant.c
View File

@ -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;