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// SPDX-License-Identifier: GPL-2.0
#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>
char _license[] SEC("license") = "GPL";
__u32 _version SEC("version") = 1;
#define SOL_CUSTOM 0xdeadbeef
#define CUSTOM_INHERIT1 0
#define CUSTOM_INHERIT2 1
#define CUSTOM_LISTENER 2
struct sockopt_inherit {
__u8 val;
};
struct {
__uint(type, BPF_MAP_TYPE_SK_STORAGE);
__uint(map_flags, BPF_F_NO_PREALLOC | BPF_F_CLONE);
__type(key, int);
__type(value, struct sockopt_inherit);
} cloned1_map SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_SK_STORAGE);
__uint(map_flags, BPF_F_NO_PREALLOC | BPF_F_CLONE);
__type(key, int);
__type(value, struct sockopt_inherit);
} cloned2_map SEC(".maps");
struct {
__uint(type, BPF_MAP_TYPE_SK_STORAGE);
__uint(map_flags, BPF_F_NO_PREALLOC);
__type(key, int);
__type(value, struct sockopt_inherit);
} listener_only_map SEC(".maps");
static __inline struct sockopt_inherit *get_storage(struct bpf_sockopt *ctx)
{
if (ctx->optname == CUSTOM_INHERIT1)
return bpf_sk_storage_get(&cloned1_map, ctx->sk, 0,
BPF_SK_STORAGE_GET_F_CREATE);
else if (ctx->optname == CUSTOM_INHERIT2)
return bpf_sk_storage_get(&cloned2_map, ctx->sk, 0,
BPF_SK_STORAGE_GET_F_CREATE);
else
return bpf_sk_storage_get(&listener_only_map, ctx->sk, 0,
BPF_SK_STORAGE_GET_F_CREATE);
}
SEC("cgroup/getsockopt")
int _getsockopt(struct bpf_sockopt *ctx)
{
__u8 *optval_end = ctx->optval_end;
struct sockopt_inherit *storage;
__u8 *optval = ctx->optval;
if (ctx->level != SOL_CUSTOM)
return 1; /* only interested in SOL_CUSTOM */
if (optval + 1 > optval_end)
return 0; /* EPERM, bounds check */
storage = get_storage(ctx);
if (!storage)
return 0; /* EPERM, couldn't get sk storage */
ctx->retval = 0; /* Reset system call return value to zero */
optval[0] = storage->val;
ctx->optlen = 1;
return 1;
}
SEC("cgroup/setsockopt")
int _setsockopt(struct bpf_sockopt *ctx)
{
__u8 *optval_end = ctx->optval_end;
struct sockopt_inherit *storage;
__u8 *optval = ctx->optval;
if (ctx->level != SOL_CUSTOM)
return 1; /* only interested in SOL_CUSTOM */
if (optval + 1 > optval_end)
return 0; /* EPERM, bounds check */
storage = get_storage(ctx);
if (!storage)
return 0; /* EPERM, couldn't get sk storage */
storage->val = optval[0];
ctx->optlen = -1;
return 1;
}
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