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selftests/bpf: Add a failure test for bpf_kptr_xchg() with local kptr

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For a bpf_kptr_xchg() with local kptr, if the map value kptr type and
allocated local obj type does not match, with the previous patch,
the below verifier error message will be logged:
  R2 is of type <allocated local obj type> but <map value kptr type> is expected

Without the previous patch, the test will have unexpected success.

Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230822050058.2887354-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Yonghong Song 2023-08-21 22:00:58 -07:00 committed by Alexei Starovoitov
parent ab6c637ad0
commit fb30159426
2 changed files with 74 additions and 1 deletions
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10
tools/testing/selftests/bpf/prog_tests/local_kptr_stash.c
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@ -5,6 +5,7 @@
#include <network_helpers.h>
#include "local_kptr_stash.skel.h"
#include "local_kptr_stash_fail.skel.h"
static void test_local_kptr_stash_simple(void)
{
LIBBPF_OPTS(bpf_test_run_opts, opts,
@ -51,10 +52,17 @@ static void test_local_kptr_stash_unstash(void)
local_kptr_stash__destroy(skel);
}
void test_local_kptr_stash_success(void)
static void test_local_kptr_stash_fail(void)
{
RUN_TESTS(local_kptr_stash_fail);
}
void test_local_kptr_stash(void)
{
if (test__start_subtest("local_kptr_stash_simple"))
test_local_kptr_stash_simple();
if (test__start_subtest("local_kptr_stash_unstash"))
test_local_kptr_stash_unstash();
if (test__start_subtest("local_kptr_stash_fail"))
test_local_kptr_stash_fail();
}

65
tools/testing/selftests/bpf/progs/local_kptr_stash_fail.c Normal file
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@ -0,0 +1,65 @@
// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
#include <vmlinux.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
#include <bpf/bpf_core_read.h>
#include "../bpf_experimental.h"
#include "bpf_misc.h"
struct node_data {
long key;
long data;
struct bpf_rb_node node;
};
struct map_value {
struct node_data __kptr *node;
};
struct node_data2 {
long key[4];
};
/* This is necessary so that LLVM generates BTF for node_data struct
* If it's not included, a fwd reference for node_data will be generated but
* no struct. Example BTF of "node" field in map_value when not included:
*
* [10] PTR '(anon)' type_id=35
* [34] FWD 'node_data' fwd_kind=struct
* [35] TYPE_TAG 'kptr_ref' type_id=34
*/
struct node_data *just_here_because_btf_bug;
struct {
__uint(type, BPF_MAP_TYPE_ARRAY);
__type(key, int);
__type(value, struct map_value);
__uint(max_entries, 2);
} some_nodes SEC(".maps");
SEC("tc")
__failure __msg("invalid kptr access, R2 type=ptr_node_data2 expected=ptr_node_data")
long stash_rb_nodes(void *ctx)
{
struct map_value *mapval;
struct node_data2 *res;
int idx = 0;
mapval = bpf_map_lookup_elem(&some_nodes, &idx);
if (!mapval)
return 1;
res = bpf_obj_new(typeof(*res));
if (!res)
return 1;
res->key[0] = 40;
res = bpf_kptr_xchg(&mapval->node, res);
if (res)
bpf_obj_drop(res);
return 0;
}
char _license[] SEC("license") = "GPL";