/* Copyright (c) 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/ptrace.h>
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#include <linux/version.h>
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#include <uapi/linux/bpf.h>
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#include <uapi/linux/seccomp.h>
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#include <uapi/linux/unistd.h>
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#include "syscall_nrs.h"
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#include "bpf_helpers.h"
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#define PROG(F) SEC("kprobe/"__stringify(F)) int bpf_func_##F
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struct bpf_map_def SEC("maps") progs = {
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.type = BPF_MAP_TYPE_PROG_ARRAY,
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.key_size = sizeof(u32),
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.value_size = sizeof(u32),
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#ifdef __mips__
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.max_entries = 6000, /* MIPS n64 syscalls start at 5000 */
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#else
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.max_entries = 1024,
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#endif
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};
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SEC("kprobe/__seccomp_filter")
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int bpf_prog1(struct pt_regs *ctx)
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{
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int sc_nr = (int)PT_REGS_PARM1(ctx);
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/* dispatch into next BPF program depending on syscall number */
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bpf_tail_call(ctx, &progs, sc_nr);
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/* fall through -> unknown syscall */
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if (sc_nr >= __NR_getuid && sc_nr <= __NR_getsid) {
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char fmt[] = "syscall=%d (one of get/set uid/pid/gid)\n";
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bpf_trace_printk(fmt, sizeof(fmt), sc_nr);
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}
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return 0;
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}
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/* we jump here when syscall number == __NR_write */
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PROG(SYS__NR_write)(struct pt_regs *ctx)
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{
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struct seccomp_data sd;
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bpf_probe_read(&sd, sizeof(sd), (void *)PT_REGS_PARM2(ctx));
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if (sd.args[2] == 512) {
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char fmt[] = "write(fd=%d, buf=%p, size=%d)\n";
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bpf_trace_printk(fmt, sizeof(fmt),
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sd.args[0], sd.args[1], sd.args[2]);
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}
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return 0;
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}
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PROG(SYS__NR_read)(struct pt_regs *ctx)
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{
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struct seccomp_data sd;
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bpf_probe_read(&sd, sizeof(sd), (void *)PT_REGS_PARM2(ctx));
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if (sd.args[2] > 128 && sd.args[2] <= 1024) {
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char fmt[] = "read(fd=%d, buf=%p, size=%d)\n";
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bpf_trace_printk(fmt, sizeof(fmt),
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sd.args[0], sd.args[1], sd.args[2]);
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}
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return 0;
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}
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PROG(SYS__NR_mmap)(struct pt_regs *ctx)
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{
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char fmt[] = "mmap\n";
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bpf_trace_printk(fmt, sizeof(fmt));
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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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