72 lines
1.4 KiB
C
72 lines
1.4 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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#include <netinet/in.h>
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#include <linux/bpf.h>
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#include <bpf/bpf_helpers.h>
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char _license[] SEC("license") = "GPL";
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__u32 _version SEC("version") = 1;
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SEC("cgroup/getsockopt/child")
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int _getsockopt_child(struct bpf_sockopt *ctx)
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{
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__u8 *optval_end = ctx->optval_end;
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__u8 *optval = ctx->optval;
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if (ctx->level != SOL_IP || ctx->optname != IP_TOS)
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return 1;
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if (optval + 1 > optval_end)
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return 0; /* EPERM, bounds check */
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if (optval[0] != 0x80)
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return 0; /* EPERM, unexpected optval from the kernel */
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ctx->retval = 0; /* Reset system call return value to zero */
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optval[0] = 0x90;
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ctx->optlen = 1;
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return 1;
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}
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SEC("cgroup/getsockopt/parent")
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int _getsockopt_parent(struct bpf_sockopt *ctx)
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{
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__u8 *optval_end = ctx->optval_end;
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__u8 *optval = ctx->optval;
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if (ctx->level != SOL_IP || ctx->optname != IP_TOS)
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return 1;
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if (optval + 1 > optval_end)
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return 0; /* EPERM, bounds check */
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if (optval[0] != 0x90)
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return 0; /* EPERM, unexpected optval from the kernel */
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ctx->retval = 0; /* Reset system call return value to zero */
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optval[0] = 0xA0;
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ctx->optlen = 1;
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return 1;
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}
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SEC("cgroup/setsockopt")
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int _setsockopt(struct bpf_sockopt *ctx)
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{
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__u8 *optval_end = ctx->optval_end;
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__u8 *optval = ctx->optval;
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if (ctx->level != SOL_IP || ctx->optname != IP_TOS)
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return 1;
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if (optval + 1 > optval_end)
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return 0; /* EPERM, bounds check */
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optval[0] += 0x10;
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ctx->optlen = 1;
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return 1;
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}
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