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selftests/bpf: Add some negative tests

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Add a few negative tests for common mistakes with using percpu kptr
including:
  - store to percpu kptr.
  - type mistach in bpf_kptr_xchg arguments.
  - sleepable prog with untrusted arg for bpf_this_cpu_ptr().
  - bpf_percpu_obj_new && bpf_obj_drop, and bpf_obj_new && bpf_percpu_obj_drop
  - struct with ptr for bpf_percpu_obj_new
  - struct with special field (e.g., bpf_spin_lock) for bpf_percpu_obj_new

Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230827152832.2002421-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Yonghong Song 2023-08-27 08:28:32 -07:00 committed by Alexei Starovoitov
parent dfae1eeee9
commit 1bd7931728
2 changed files with 171 additions and 0 deletions
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7
tools/testing/selftests/bpf/prog_tests/percpu_alloc.c
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@ -2,6 +2,7 @@
#include <test_progs.h>
#include "percpu_alloc_array.skel.h"
#include "percpu_alloc_cgrp_local_storage.skel.h"
#include "percpu_alloc_fail.skel.h"
static void test_array(void)
{
@ -107,6 +108,10 @@ close_fd:
close(cgroup_fd);
}
static void test_failure(void) {
RUN_TESTS(percpu_alloc_fail);
}
void test_percpu_alloc(void)
{
if (test__start_subtest("array"))
@ -115,4 +120,6 @@ void test_percpu_alloc(void)
test_array_sleepable();
if (test__start_subtest("cgrp_local_storage"))
test_cgrp_local_storage();
if (test__start_subtest("failure_tests"))
test_failure();
}

164
tools/testing/selftests/bpf/progs/percpu_alloc_fail.c Normal file
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@ -0,0 +1,164 @@
#include "bpf_experimental.h"
#include "bpf_misc.h"
struct val_t {
long b, c, d;
};
struct val2_t {
long b;
};
struct val_with_ptr_t {
char *p;
};
struct val_with_rb_root_t {
struct bpf_spin_lock lock;
};
struct elem {
long sum;
struct val_t __percpu_kptr *pc;
};
struct {
__uint(type, BPF_MAP_TYPE_ARRAY);
__uint(max_entries, 1);
__type(key, int);
__type(value, struct elem);
} array SEC(".maps");
long ret;
SEC("?fentry/bpf_fentry_test1")
__failure __msg("store to referenced kptr disallowed")
int BPF_PROG(test_array_map_1)
{
struct val_t __percpu_kptr *p;
struct elem *e;
int index = 0;
e = bpf_map_lookup_elem(&array, &index);
if (!e)
return 0;
p = bpf_percpu_obj_new(struct val_t);
if (!p)
return 0;
p = bpf_kptr_xchg(&e->pc, p);
if (p)
bpf_percpu_obj_drop(p);
e->pc = (struct val_t __percpu_kptr *)ret;
return 0;
}
SEC("?fentry/bpf_fentry_test1")
__failure __msg("invalid kptr access, R2 type=percpu_ptr_val2_t expected=ptr_val_t")
int BPF_PROG(test_array_map_2)
{
struct val2_t __percpu_kptr *p2;
struct val_t __percpu_kptr *p;
struct elem *e;
int index = 0;
e = bpf_map_lookup_elem(&array, &index);
if (!e)
return 0;
p2 = bpf_percpu_obj_new(struct val2_t);
if (!p2)
return 0;
p = bpf_kptr_xchg(&e->pc, p2);
if (p)
bpf_percpu_obj_drop(p);
return 0;
}
SEC("?fentry.s/bpf_fentry_test1")
__failure __msg("R1 type=scalar expected=percpu_ptr_, percpu_rcu_ptr_, percpu_trusted_ptr_")
int BPF_PROG(test_array_map_3)
{
struct val_t __percpu_kptr *p, *p1;
struct val_t *v;
struct elem *e;
int index = 0;
e = bpf_map_lookup_elem(&array, &index);
if (!e)
return 0;
p = bpf_percpu_obj_new(struct val_t);
if (!p)
return 0;
p1 = bpf_kptr_xchg(&e->pc, p);
if (p1)
bpf_percpu_obj_drop(p1);
v = bpf_this_cpu_ptr(p);
ret = v->b;
return 0;
}
SEC("?fentry.s/bpf_fentry_test1")
__failure __msg("arg#0 expected for bpf_percpu_obj_drop_impl()")
int BPF_PROG(test_array_map_4)
{
struct val_t __percpu_kptr *p;
p = bpf_percpu_obj_new(struct val_t);
if (!p)
return 0;
bpf_obj_drop(p);
return 0;
}
SEC("?fentry.s/bpf_fentry_test1")
__failure __msg("arg#0 expected for bpf_obj_drop_impl()")
int BPF_PROG(test_array_map_5)
{
struct val_t *p;
p = bpf_obj_new(struct val_t);
if (!p)
return 0;
bpf_percpu_obj_drop(p);
return 0;
}
SEC("?fentry.s/bpf_fentry_test1")
__failure __msg("bpf_percpu_obj_new type ID argument must be of a struct of scalars")
int BPF_PROG(test_array_map_6)
{
struct val_with_ptr_t __percpu_kptr *p;
p = bpf_percpu_obj_new(struct val_with_ptr_t);
if (!p)
return 0;
bpf_percpu_obj_drop(p);
return 0;
}
SEC("?fentry.s/bpf_fentry_test1")
__failure __msg("bpf_percpu_obj_new type ID argument must not contain special fields")
int BPF_PROG(test_array_map_7)
{
struct val_with_rb_root_t __percpu_kptr *p;
p = bpf_percpu_obj_new(struct val_with_rb_root_t);
if (!p)
return 0;
bpf_percpu_obj_drop(p);
return 0;
}
char _license[] SEC("license") = "GPL";