1 // SPDX-License-Identifier: GPL-2.0
2 #include <vmlinux.h>
3 #include <bpf/bpf_helpers.h>
4
5 #include "bpf_misc.h"
6
7 struct hmap_elem {
8 struct bpf_timer timer;
9 };
10
11 struct {
12 __uint(type, BPF_MAP_TYPE_HASH);
13 __uint(max_entries, 64);
14 __type(key, int);
15 __type(value, struct hmap_elem);
16 } hmap SEC(".maps");
17
18 __attribute__((noinline))
19 static int timer_cb(void *map, int *key, struct bpf_timer *timer)
20 {
21 volatile char buf[256] = {};
22 return buf[69];
23 }
24
25 __attribute__((noinline))
26 static int bad_timer_cb(void *map, int *key, struct bpf_timer *timer)
27 {
28 volatile char buf[300] = {};
29 return buf[255] + timer_cb(NULL, NULL, NULL);
30 }
31
32 SEC("tc")
33 __failure __msg("combined stack size of 2 calls is")
34 int pseudo_call_check(struct __sk_buff *ctx)
35 {
36 struct hmap_elem *elem;
37 volatile char buf[256] = {};
38
39 elem = bpf_map_lookup_elem(&hmap, &(int){0});
40 if (!elem)
41 return 0;
42
43 timer_cb(NULL, NULL, NULL);
44 return bpf_timer_set_callback(&elem->timer, timer_cb) + buf[0];
45 }
46
47 SEC("tc")
48 __failure __msg("combined stack size of 2 calls is")
49 int async_call_root_check(struct __sk_buff *ctx)
50 {
51 struct hmap_elem *elem;
52 volatile char buf[256] = {};
53
54 elem = bpf_map_lookup_elem(&hmap, &(int){0});
55 if (!elem)
56 return 0;
57
58 return bpf_timer_set_callback(&elem->timer, bad_timer_cb) + buf[0];
59 }
60
61 char _license[] SEC("license") = "GPL";
62
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