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1// SPDX-License-Identifier: GPL-2.02#include <linux/bpf.h>3#include <bpf/bpf_helpers.h>4 5char _license[] SEC("license") = "GPL";6 7#define SOL_CUSTOM 0xdeadbeef8#define CUSTOM_INHERIT1 09#define CUSTOM_INHERIT2 110#define CUSTOM_LISTENER 211 12__s32 page_size = 0;13 14struct sockopt_inherit {15 __u8 val;16};17 18struct {19 __uint(type, BPF_MAP_TYPE_SK_STORAGE);20 __uint(map_flags, BPF_F_NO_PREALLOC | BPF_F_CLONE);21 __type(key, int);22 __type(value, struct sockopt_inherit);23} cloned1_map SEC(".maps");24 25struct {26 __uint(type, BPF_MAP_TYPE_SK_STORAGE);27 __uint(map_flags, BPF_F_NO_PREALLOC | BPF_F_CLONE);28 __type(key, int);29 __type(value, struct sockopt_inherit);30} cloned2_map SEC(".maps");31 32struct {33 __uint(type, BPF_MAP_TYPE_SK_STORAGE);34 __uint(map_flags, BPF_F_NO_PREALLOC);35 __type(key, int);36 __type(value, struct sockopt_inherit);37} listener_only_map SEC(".maps");38 39static __inline struct sockopt_inherit *get_storage(struct bpf_sockopt *ctx)40{41 if (ctx->optname == CUSTOM_INHERIT1)42 return bpf_sk_storage_get(&cloned1_map, ctx->sk, 0,43 BPF_SK_STORAGE_GET_F_CREATE);44 else if (ctx->optname == CUSTOM_INHERIT2)45 return bpf_sk_storage_get(&cloned2_map, ctx->sk, 0,46 BPF_SK_STORAGE_GET_F_CREATE);47 else48 return bpf_sk_storage_get(&listener_only_map, ctx->sk, 0,49 BPF_SK_STORAGE_GET_F_CREATE);50}51 52SEC("cgroup/getsockopt")53int _getsockopt(struct bpf_sockopt *ctx)54{55 __u8 *optval_end = ctx->optval_end;56 struct sockopt_inherit *storage;57 __u8 *optval = ctx->optval;58 59 if (ctx->level != SOL_CUSTOM)60 goto out; /* only interested in SOL_CUSTOM */61 62 if (optval + 1 > optval_end)63 return 0; /* EPERM, bounds check */64 65 storage = get_storage(ctx);66 if (!storage)67 return 0; /* EPERM, couldn't get sk storage */68 69 ctx->retval = 0; /* Reset system call return value to zero */70 71 optval[0] = storage->val;72 ctx->optlen = 1;73 74 return 1;75 76out:77 /* optval larger than PAGE_SIZE use kernel's buffer. */78 if (ctx->optlen > page_size)79 ctx->optlen = 0;80 return 1;81}82 83SEC("cgroup/setsockopt")84int _setsockopt(struct bpf_sockopt *ctx)85{86 __u8 *optval_end = ctx->optval_end;87 struct sockopt_inherit *storage;88 __u8 *optval = ctx->optval;89 90 if (ctx->level != SOL_CUSTOM)91 goto out; /* only interested in SOL_CUSTOM */92 93 if (optval + 1 > optval_end)94 return 0; /* EPERM, bounds check */95 96 storage = get_storage(ctx);97 if (!storage)98 return 0; /* EPERM, couldn't get sk storage */99 100 storage->val = optval[0];101 ctx->optlen = -1;102 103 return 1;104 105out:106 /* optval larger than PAGE_SIZE use kernel's buffer. */107 if (ctx->optlen > page_size)108 ctx->optlen = 0;109 return 1;110}111