87 lines
2.0 KiB
C
87 lines
2.0 KiB
C
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/* Copyright (c) 2013-2015 PLUMgrid, http://plumgrid.com
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*/
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#include <linux/skbuff.h>
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#include <linux/netdevice.h>
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#include <linux/version.h>
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#include <uapi/linux/bpf.h>
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#include "bpf_helpers.h"
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struct bpf_map_def SEC("maps") my_map = {
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.type = BPF_MAP_TYPE_HASH,
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.key_size = sizeof(long),
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.value_size = sizeof(long),
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.max_entries = 1024,
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};
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/* kprobe is NOT a stable ABI. If kernel internals change this bpf+kprobe
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* example will no longer be meaningful
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*/
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SEC("kprobe/kfree_skb")
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int bpf_prog2(struct pt_regs *ctx)
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{
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long loc = 0;
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long init_val = 1;
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long *value;
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/* x64 specific: read ip of kfree_skb caller.
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* non-portable version of __builtin_return_address(0)
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*/
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bpf_probe_read(&loc, sizeof(loc), (void *)ctx->sp);
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value = bpf_map_lookup_elem(&my_map, &loc);
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if (value)
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*value += 1;
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else
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bpf_map_update_elem(&my_map, &loc, &init_val, BPF_ANY);
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return 0;
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}
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static unsigned int log2(unsigned int v)
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{
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unsigned int r;
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unsigned int shift;
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r = (v > 0xFFFF) << 4; v >>= r;
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shift = (v > 0xFF) << 3; v >>= shift; r |= shift;
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shift = (v > 0xF) << 2; v >>= shift; r |= shift;
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shift = (v > 0x3) << 1; v >>= shift; r |= shift;
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r |= (v >> 1);
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return r;
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}
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static unsigned int log2l(unsigned long v)
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{
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unsigned int hi = v >> 32;
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if (hi)
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return log2(hi) + 32;
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else
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return log2(v);
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}
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struct bpf_map_def SEC("maps") my_hist_map = {
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.type = BPF_MAP_TYPE_ARRAY,
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.key_size = sizeof(u32),
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.value_size = sizeof(long),
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.max_entries = 64,
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};
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SEC("kprobe/sys_write")
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int bpf_prog3(struct pt_regs *ctx)
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{
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long write_size = ctx->dx; /* arg3 */
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long init_val = 1;
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long *value;
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u32 index = log2l(write_size);
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value = bpf_map_lookup_elem(&my_hist_map, &index);
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if (value)
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__sync_fetch_and_add(value, 1);
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return 0;
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}
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char _license[] SEC("license") = "GPL";
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u32 _version SEC("version") = LINUX_VERSION_CODE;
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