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1/* Copyright (c) 2015 PLUMgrid, http://plumgrid.com2 *3 * This program is free software; you can redistribute it and/or4 * modify it under the terms of version 2 of the GNU General Public5 * License as published by the Free Software Foundation.6 */7#include "vmlinux.h"8#include "syscall_nrs.h"9#include <linux/version.h>10#include <uapi/linux/unistd.h>11#include <bpf/bpf_helpers.h>12#include <bpf/bpf_tracing.h>13#include <bpf/bpf_core_read.h>14 15#define __stringify(x) #x16#define PROG(F) SEC("kprobe/"__stringify(F)) int bpf_func_##F17 18struct {19 __uint(type, BPF_MAP_TYPE_PROG_ARRAY);20 __uint(key_size, sizeof(u32));21 __uint(value_size, sizeof(u32));22#ifdef __mips__23 __uint(max_entries, 6000); /* MIPS n64 syscalls start at 5000 */24#else25 __uint(max_entries, 1024);26#endif27} progs SEC(".maps");28 29SEC("kprobe/__seccomp_filter")30int bpf_prog1(struct pt_regs *ctx)31{32 int sc_nr = (int)PT_REGS_PARM1(ctx);33 34 /* dispatch into next BPF program depending on syscall number */35 bpf_tail_call(ctx, &progs, sc_nr);36 37 /* fall through -> unknown syscall */38 if (sc_nr >= __NR_getuid && sc_nr <= __NR_getsid) {39 char fmt[] = "syscall=%d (one of get/set uid/pid/gid)\n";40 bpf_trace_printk(fmt, sizeof(fmt), sc_nr);41 }42 return 0;43}44 45/* we jump here when syscall number == __NR_write */46PROG(SYS__NR_write)(struct pt_regs *ctx)47{48 struct seccomp_data sd;49 50 bpf_core_read(&sd, sizeof(sd), (void *)PT_REGS_PARM2(ctx));51 if (sd.args[2] == 512) {52 char fmt[] = "write(fd=%d, buf=%p, size=%d)\n";53 bpf_trace_printk(fmt, sizeof(fmt),54 sd.args[0], sd.args[1], sd.args[2]);55 }56 return 0;57}58 59PROG(SYS__NR_read)(struct pt_regs *ctx)60{61 struct seccomp_data sd;62 63 bpf_core_read(&sd, sizeof(sd), (void *)PT_REGS_PARM2(ctx));64 if (sd.args[2] > 128 && sd.args[2] <= 1024) {65 char fmt[] = "read(fd=%d, buf=%p, size=%d)\n";66 bpf_trace_printk(fmt, sizeof(fmt),67 sd.args[0], sd.args[1], sd.args[2]);68 }69 return 0;70}71 72#ifdef __NR_mmap273PROG(SYS__NR_mmap2)(struct pt_regs *ctx)74{75 char fmt[] = "mmap2\n";76 77 bpf_trace_printk(fmt, sizeof(fmt));78 return 0;79}80#endif81 82#ifdef __NR_mmap83PROG(SYS__NR_mmap)(struct pt_regs *ctx)84{85 char fmt[] = "mmap\n";86 87 bpf_trace_printk(fmt, sizeof(fmt));88 return 0;89}90#endif91 92char _license[] SEC("license") = "GPL";93u32 _version SEC("version") = LINUX_VERSION_CODE;94