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selftests/bpf: Extend map-in-map selftest to detect memory leaks

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Add test validating that all inner maps are released properly after skeleton
is destroyed. To ensure determinism, trigger kernel-side synchronize_rcu()
before checking map existence by their IDs.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200729040913.2815687-2-andriin@fb.com
This commit is contained in:
Andrii Nakryiko 2020-07-28 21:09:13 -07:00 • committed by Daniel Borkmann
parent 1d4e1eab45
commit 0ba5834841
1 changed files with 110 additions and 14 deletions
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124
tools/testing/selftests/bpf/prog_tests/btf_map_in_map.c
View file

@ -5,10 +5,60 @@
#include "test_btf_map_in_map.skel.h"
static int duration;
static __u32 bpf_map_id(struct bpf_map *map)
{
struct bpf_map_info info;
__u32 info_len = sizeof(info);
int err;
memset(&info, 0, info_len);
err = bpf_obj_get_info_by_fd(bpf_map__fd(map), &info, &info_len);
if (err)
return 0;
return info.id;
}
/*
* Trigger synchronize_rcu() in kernel.
*
* ARRAY_OF_MAPS/HASH_OF_MAPS lookup/update operations trigger synchronize_rcu()
* if looking up an existing non-NULL element or updating the map with a valid
* inner map FD. Use this fact to trigger synchronize_rcu(): create map-in-map,
* create a trivial ARRAY map, update map-in-map with ARRAY inner map. Then
* cleanup. At the end, at least one synchronize_rcu() would be called.
*/
static int kern_sync_rcu(void)
{
int inner_map_fd, outer_map_fd, err, zero = 0;
inner_map_fd = bpf_create_map(BPF_MAP_TYPE_ARRAY, 4, 4, 1, 0);
if (CHECK(inner_map_fd < 0, "inner_map_create", "failed %d\n", -errno))
return -1;
outer_map_fd = bpf_create_map_in_map(BPF_MAP_TYPE_ARRAY_OF_MAPS, NULL,
sizeof(int), inner_map_fd, 1, 0);
if (CHECK(outer_map_fd < 0, "outer_map_create", "failed %d\n", -errno)) {
close(inner_map_fd);
return -1;
}
err = bpf_map_update_elem(outer_map_fd, &zero, &inner_map_fd, 0);
if (err)
err = -errno;
CHECK(err, "outer_map_update", "failed %d\n", err);
close(inner_map_fd);
close(outer_map_fd);
return err;
}
void test_btf_map_in_map(void)
{
int duration = 0, err, key = 0, val;
struct test_btf_map_in_map* skel;
int err, key = 0, val, i;
struct test_btf_map_in_map *skel;
int outer_arr_fd, outer_hash_fd;
int fd, map1_fd, map2_fd, map1_id, map2_id;
skel = test_btf_map_in_map__open_and_load();
if (CHECK(!skel, "skel_open", "failed to open&load skeleton\n"))
@ -18,32 +68,78 @@ void test_btf_map_in_map(void)
if (CHECK(err, "skel_attach", "skeleton attach failed: %d\n", err))
goto cleanup;
map1_fd = bpf_map__fd(skel->maps.inner_map1);
map2_fd = bpf_map__fd(skel->maps.inner_map2);
outer_arr_fd = bpf_map__fd(skel->maps.outer_arr);
outer_hash_fd = bpf_map__fd(skel->maps.outer_hash);
/* inner1 = input, inner2 = input + 1 */
val = bpf_map__fd(skel->maps.inner_map1);
bpf_map_update_elem(bpf_map__fd(skel->maps.outer_arr), &key, &val, 0);
val = bpf_map__fd(skel->maps.inner_map2);
bpf_map_update_elem(bpf_map__fd(skel->maps.outer_hash), &key, &val, 0);
map1_fd = bpf_map__fd(skel->maps.inner_map1);
bpf_map_update_elem(outer_arr_fd, &key, &map1_fd, 0);
map2_fd = bpf_map__fd(skel->maps.inner_map2);
bpf_map_update_elem(outer_hash_fd, &key, &map2_fd, 0);
skel->bss->input = 1;
usleep(1);
bpf_map_lookup_elem(bpf_map__fd(skel->maps.inner_map1), &key, &val);
bpf_map_lookup_elem(map1_fd, &key, &val);
CHECK(val != 1, "inner1", "got %d != exp %d\n", val, 1);
bpf_map_lookup_elem(bpf_map__fd(skel->maps.inner_map2), &key, &val);
bpf_map_lookup_elem(map2_fd, &key, &val);
CHECK(val != 2, "inner2", "got %d != exp %d\n", val, 2);
/* inner1 = input + 1, inner2 = input */
val = bpf_map__fd(skel->maps.inner_map2);
bpf_map_update_elem(bpf_map__fd(skel->maps.outer_arr), &key, &val, 0);
val = bpf_map__fd(skel->maps.inner_map1);
bpf_map_update_elem(bpf_map__fd(skel->maps.outer_hash), &key, &val, 0);
bpf_map_update_elem(outer_arr_fd, &key, &map2_fd, 0);
bpf_map_update_elem(outer_hash_fd, &key, &map1_fd, 0);
skel->bss->input = 3;
usleep(1);
bpf_map_lookup_elem(bpf_map__fd(skel->maps.inner_map1), &key, &val);
bpf_map_lookup_elem(map1_fd, &key, &val);
CHECK(val != 4, "inner1", "got %d != exp %d\n", val, 4);
bpf_map_lookup_elem(bpf_map__fd(skel->maps.inner_map2), &key, &val);
bpf_map_lookup_elem(map2_fd, &key, &val);
CHECK(val != 3, "inner2", "got %d != exp %d\n", val, 3);
for (i = 0; i < 5; i++) {
val = i % 2 ? map1_fd : map2_fd;
err = bpf_map_update_elem(outer_hash_fd, &key, &val, 0);
if (CHECK_FAIL(err)) {
printf("failed to update hash_of_maps on iter #%d\n", i);
goto cleanup;
}
err = bpf_map_update_elem(outer_arr_fd, &key, &val, 0);
if (CHECK_FAIL(err)) {
printf("failed to update hash_of_maps on iter #%d\n", i);
goto cleanup;
}
}
map1_id = bpf_map_id(skel->maps.inner_map1);
map2_id = bpf_map_id(skel->maps.inner_map2);
CHECK(map1_id == 0, "map1_id", "failed to get ID 1\n");
CHECK(map2_id == 0, "map2_id", "failed to get ID 2\n");
test_btf_map_in_map__destroy(skel);
skel = NULL;
/* we need to either wait for or force synchronize_rcu(), before
* checking for "still exists" condition, otherwise map could still be
* resolvable by ID, causing false positives.
*
* Older kernels (5.8 and earlier) freed map only after two
* synchronize_rcu()s, so trigger two, to be entirely sure.
*/
CHECK(kern_sync_rcu(), "sync_rcu", "failed\n");
CHECK(kern_sync_rcu(), "sync_rcu", "failed\n");
fd = bpf_map_get_fd_by_id(map1_id);
if (CHECK(fd >= 0, "map1_leak", "inner_map1 leaked!\n")) {
close(fd);
goto cleanup;
}
fd = bpf_map_get_fd_by_id(map2_id);
if (CHECK(fd >= 0, "map2_leak", "inner_map2 leaked!\n")) {
close(fd);
goto cleanup;
}
cleanup:
test_btf_map_in_map__destroy(skel);
}