1// SPDX-License-Identifier: GPL-2.0
 2#include <netinet/in.h>
 3#include <linux/bpf.h>
 4#include <bpf/bpf_helpers.h>
 5
 6char _license[] SEC("license") = "GPL";
 7__u32 _version SEC("version") = 1;
 8
 9SEC("cgroup/getsockopt/child")
10int _getsockopt_child(struct bpf_sockopt *ctx)
11{
12	__u8 *optval_end = ctx->optval_end;
13	__u8 *optval = ctx->optval;
14
15	if (ctx->level != SOL_IP || ctx->optname != IP_TOS)
16		return 1;
17
18	if (optval + 1 > optval_end)
19		return 0; /* EPERM, bounds check */
20
21	if (optval[0] != 0x80)
22		return 0; /* EPERM, unexpected optval from the kernel */
23
24	ctx->retval = 0; /* Reset system call return value to zero */
25
26	optval[0] = 0x90;
27	ctx->optlen = 1;
28
29	return 1;
30}
31
32SEC("cgroup/getsockopt/parent")
33int _getsockopt_parent(struct bpf_sockopt *ctx)
34{
35	__u8 *optval_end = ctx->optval_end;
36	__u8 *optval = ctx->optval;
37
38	if (ctx->level != SOL_IP || ctx->optname != IP_TOS)
39		return 1;
40
41	if (optval + 1 > optval_end)
42		return 0; /* EPERM, bounds check */
43
44	if (optval[0] != 0x90)
45		return 0; /* EPERM, unexpected optval from the kernel */
46
47	ctx->retval = 0; /* Reset system call return value to zero */
48
49	optval[0] = 0xA0;
50	ctx->optlen = 1;
51
52	return 1;
53}
54
55SEC("cgroup/setsockopt")
56int _setsockopt(struct bpf_sockopt *ctx)
57{
58	__u8 *optval_end = ctx->optval_end;
59	__u8 *optval = ctx->optval;
60
61	if (ctx->level != SOL_IP || ctx->optname != IP_TOS)
62		return 1;
63
64	if (optval + 1 > optval_end)
65		return 0; /* EPERM, bounds check */
66
67	optval[0] += 0x10;
68	ctx->optlen = 1;
69
70	return 1;
71}

 1// SPDX-License-Identifier: GPL-2.0
 2#include <netinet/in.h>
 3#include <linux/bpf.h>
 4#include <bpf/bpf_helpers.h>
 5
 6char _license[] SEC("license") = "GPL";
 
 7
 8SEC("cgroup/getsockopt")
 9int _getsockopt_child(struct bpf_sockopt *ctx)
10{
11	__u8 *optval_end = ctx->optval_end;
12	__u8 *optval = ctx->optval;
13
14	if (ctx->level != SOL_IP || ctx->optname != IP_TOS)
15		return 1;
16
17	if (optval + 1 > optval_end)
18		return 0; /* EPERM, bounds check */
19
20	if (optval[0] != 0x80)
21		return 0; /* EPERM, unexpected optval from the kernel */
22
23	ctx->retval = 0; /* Reset system call return value to zero */
24
25	optval[0] = 0x90;
26	ctx->optlen = 1;
27
28	return 1;
29}
30
31SEC("cgroup/getsockopt")
32int _getsockopt_parent(struct bpf_sockopt *ctx)
33{
34	__u8 *optval_end = ctx->optval_end;
35	__u8 *optval = ctx->optval;
36
37	if (ctx->level != SOL_IP || ctx->optname != IP_TOS)
38		return 1;
39
40	if (optval + 1 > optval_end)
41		return 0; /* EPERM, bounds check */
42
43	if (optval[0] != 0x90)
44		return 0; /* EPERM, unexpected optval from the kernel */
45
46	ctx->retval = 0; /* Reset system call return value to zero */
47
48	optval[0] = 0xA0;
49	ctx->optlen = 1;
50
51	return 1;
52}
53
54SEC("cgroup/setsockopt")
55int _setsockopt(struct bpf_sockopt *ctx)
56{
57	__u8 *optval_end = ctx->optval_end;
58	__u8 *optval = ctx->optval;
59
60	if (ctx->level != SOL_IP || ctx->optname != IP_TOS)
61		return 1;
62
63	if (optval + 1 > optval_end)
64		return 0; /* EPERM, bounds check */
65
66	optval[0] += 0x10;
67	ctx->optlen = 1;
68
69	return 1;
70}