1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0
2*4882a593Smuzhiyun #include <linux/bpf.h>
3*4882a593Smuzhiyun #include <bpf/bpf_helpers.h>
4*4882a593Smuzhiyun
5*4882a593Smuzhiyun char _license[] SEC("license") = "GPL";
6*4882a593Smuzhiyun __u32 _version SEC("version") = 1;
7*4882a593Smuzhiyun
8*4882a593Smuzhiyun #define SOL_CUSTOM 0xdeadbeef
9*4882a593Smuzhiyun #define CUSTOM_INHERIT1 0
10*4882a593Smuzhiyun #define CUSTOM_INHERIT2 1
11*4882a593Smuzhiyun #define CUSTOM_LISTENER 2
12*4882a593Smuzhiyun
13*4882a593Smuzhiyun struct sockopt_inherit {
14*4882a593Smuzhiyun __u8 val;
15*4882a593Smuzhiyun };
16*4882a593Smuzhiyun
17*4882a593Smuzhiyun struct {
18*4882a593Smuzhiyun __uint(type, BPF_MAP_TYPE_SK_STORAGE);
19*4882a593Smuzhiyun __uint(map_flags, BPF_F_NO_PREALLOC | BPF_F_CLONE);
20*4882a593Smuzhiyun __type(key, int);
21*4882a593Smuzhiyun __type(value, struct sockopt_inherit);
22*4882a593Smuzhiyun } cloned1_map SEC(".maps");
23*4882a593Smuzhiyun
24*4882a593Smuzhiyun struct {
25*4882a593Smuzhiyun __uint(type, BPF_MAP_TYPE_SK_STORAGE);
26*4882a593Smuzhiyun __uint(map_flags, BPF_F_NO_PREALLOC | BPF_F_CLONE);
27*4882a593Smuzhiyun __type(key, int);
28*4882a593Smuzhiyun __type(value, struct sockopt_inherit);
29*4882a593Smuzhiyun } cloned2_map SEC(".maps");
30*4882a593Smuzhiyun
31*4882a593Smuzhiyun struct {
32*4882a593Smuzhiyun __uint(type, BPF_MAP_TYPE_SK_STORAGE);
33*4882a593Smuzhiyun __uint(map_flags, BPF_F_NO_PREALLOC);
34*4882a593Smuzhiyun __type(key, int);
35*4882a593Smuzhiyun __type(value, struct sockopt_inherit);
36*4882a593Smuzhiyun } listener_only_map SEC(".maps");
37*4882a593Smuzhiyun
get_storage(struct bpf_sockopt * ctx)38*4882a593Smuzhiyun static __inline struct sockopt_inherit *get_storage(struct bpf_sockopt *ctx)
39*4882a593Smuzhiyun {
40*4882a593Smuzhiyun if (ctx->optname == CUSTOM_INHERIT1)
41*4882a593Smuzhiyun return bpf_sk_storage_get(&cloned1_map, ctx->sk, 0,
42*4882a593Smuzhiyun BPF_SK_STORAGE_GET_F_CREATE);
43*4882a593Smuzhiyun else if (ctx->optname == CUSTOM_INHERIT2)
44*4882a593Smuzhiyun return bpf_sk_storage_get(&cloned2_map, ctx->sk, 0,
45*4882a593Smuzhiyun BPF_SK_STORAGE_GET_F_CREATE);
46*4882a593Smuzhiyun else
47*4882a593Smuzhiyun return bpf_sk_storage_get(&listener_only_map, ctx->sk, 0,
48*4882a593Smuzhiyun BPF_SK_STORAGE_GET_F_CREATE);
49*4882a593Smuzhiyun }
50*4882a593Smuzhiyun
51*4882a593Smuzhiyun SEC("cgroup/getsockopt")
_getsockopt(struct bpf_sockopt * ctx)52*4882a593Smuzhiyun int _getsockopt(struct bpf_sockopt *ctx)
53*4882a593Smuzhiyun {
54*4882a593Smuzhiyun __u8 *optval_end = ctx->optval_end;
55*4882a593Smuzhiyun struct sockopt_inherit *storage;
56*4882a593Smuzhiyun __u8 *optval = ctx->optval;
57*4882a593Smuzhiyun
58*4882a593Smuzhiyun if (ctx->level != SOL_CUSTOM)
59*4882a593Smuzhiyun return 1; /* only interested in SOL_CUSTOM */
60*4882a593Smuzhiyun
61*4882a593Smuzhiyun if (optval + 1 > optval_end)
62*4882a593Smuzhiyun return 0; /* EPERM, bounds check */
63*4882a593Smuzhiyun
64*4882a593Smuzhiyun storage = get_storage(ctx);
65*4882a593Smuzhiyun if (!storage)
66*4882a593Smuzhiyun return 0; /* EPERM, couldn't get sk storage */
67*4882a593Smuzhiyun
68*4882a593Smuzhiyun ctx->retval = 0; /* Reset system call return value to zero */
69*4882a593Smuzhiyun
70*4882a593Smuzhiyun optval[0] = storage->val;
71*4882a593Smuzhiyun ctx->optlen = 1;
72*4882a593Smuzhiyun
73*4882a593Smuzhiyun return 1;
74*4882a593Smuzhiyun }
75*4882a593Smuzhiyun
76*4882a593Smuzhiyun SEC("cgroup/setsockopt")
_setsockopt(struct bpf_sockopt * ctx)77*4882a593Smuzhiyun int _setsockopt(struct bpf_sockopt *ctx)
78*4882a593Smuzhiyun {
79*4882a593Smuzhiyun __u8 *optval_end = ctx->optval_end;
80*4882a593Smuzhiyun struct sockopt_inherit *storage;
81*4882a593Smuzhiyun __u8 *optval = ctx->optval;
82*4882a593Smuzhiyun
83*4882a593Smuzhiyun if (ctx->level != SOL_CUSTOM)
84*4882a593Smuzhiyun return 1; /* only interested in SOL_CUSTOM */
85*4882a593Smuzhiyun
86*4882a593Smuzhiyun if (optval + 1 > optval_end)
87*4882a593Smuzhiyun return 0; /* EPERM, bounds check */
88*4882a593Smuzhiyun
89*4882a593Smuzhiyun storage = get_storage(ctx);
90*4882a593Smuzhiyun if (!storage)
91*4882a593Smuzhiyun return 0; /* EPERM, couldn't get sk storage */
92*4882a593Smuzhiyun
93*4882a593Smuzhiyun storage->val = optval[0];
94*4882a593Smuzhiyun ctx->optlen = -1;
95*4882a593Smuzhiyun
96*4882a593Smuzhiyun return 1;
97*4882a593Smuzhiyun }
98