1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
|
// SPDX-License-Identifier: GPL-2.0
#include <vmlinux.h>
#include <bpf/bpf_helpers.h>
#include "bpf_misc.h"
struct hmap_elem {
struct bpf_timer timer;
};
struct {
__uint(type, BPF_MAP_TYPE_HASH);
__uint(max_entries, 64);
__type(key, int);
__type(value, struct hmap_elem);
} hmap SEC(".maps");
__attribute__((noinline))
static int timer_cb(void *map, int *key, struct bpf_timer *timer)
{
volatile char buf[256] = {};
return buf[69];
}
__attribute__((noinline))
static int bad_timer_cb(void *map, int *key, struct bpf_timer *timer)
{
volatile char buf[300] = {};
return buf[255] + timer_cb(NULL, NULL, NULL);
}
SEC("tc")
__failure __msg("combined stack size of 2 calls is")
int pseudo_call_check(struct __sk_buff *ctx)
{
struct hmap_elem *elem;
volatile char buf[256] = {};
elem = bpf_map_lookup_elem(&hmap, &(int){0});
if (!elem)
return 0;
timer_cb(NULL, NULL, NULL);
return bpf_timer_set_callback(&elem->timer, timer_cb) + buf[0];
}
SEC("tc")
__failure __msg("combined stack size of 2 calls is")
int async_call_root_check(struct __sk_buff *ctx)
{
struct hmap_elem *elem;
volatile char buf[256] = {};
elem = bpf_map_lookup_elem(&hmap, &(int){0});
if (!elem)
return 0;
return bpf_timer_set_callback(&elem->timer, bad_timer_cb) + buf[0];
}
char _license[] SEC("license") = "GPL";
|
