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/* Copyright (c) 2015 PLUMgrid, http://plumgrid.com
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of version 2 of the GNU General Public
* License as published by the Free Software Foundation.
*/
#include <linux/ptrace.h>
#include <linux/version.h>
#include <uapi/linux/bpf.h>
#include <uapi/linux/seccomp.h>
#include <uapi/linux/unistd.h>
#include "syscall_nrs.h"
#include "bpf_helpers.h"
#define PROG(F) SEC("kprobe/"__stringify(F)) int bpf_func_##F
struct bpf_map_def SEC("maps") progs = {
.type = BPF_MAP_TYPE_PROG_ARRAY,
.key_size = sizeof(u32),
.value_size = sizeof(u32),
#ifdef __mips__
.max_entries = 6000, /* MIPS n64 syscalls start at 5000 */
#else
.max_entries = 1024,
#endif
};
SEC("kprobe/__seccomp_filter")
int bpf_prog1(struct pt_regs *ctx)
{
int sc_nr = (int)PT_REGS_PARM1(ctx);
/* dispatch into next BPF program depending on syscall number */
bpf_tail_call(ctx, &progs, sc_nr);
/* fall through -> unknown syscall */
if (sc_nr >= __NR_getuid && sc_nr <= __NR_getsid) {
char fmt[] = "syscall=%d (one of get/set uid/pid/gid)\n";
bpf_trace_printk(fmt, sizeof(fmt), sc_nr);
}
return 0;
}
/* we jump here when syscall number == __NR_write */
PROG(SYS__NR_write)(struct pt_regs *ctx)
{
struct seccomp_data sd;
bpf_probe_read(&sd, sizeof(sd), (void *)PT_REGS_PARM2(ctx));
if (sd.args[2] == 512) {
char fmt[] = "write(fd=%d, buf=%p, size=%d)\n";
bpf_trace_printk(fmt, sizeof(fmt),
sd.args[0], sd.args[1], sd.args[2]);
}
return 0;
}
PROG(SYS__NR_read)(struct pt_regs *ctx)
{
struct seccomp_data sd;
bpf_probe_read(&sd, sizeof(sd), (void *)PT_REGS_PARM2(ctx));
if (sd.args[2] > 128 && sd.args[2] <= 1024) {
char fmt[] = "read(fd=%d, buf=%p, size=%d)\n";
bpf_trace_printk(fmt, sizeof(fmt),
sd.args[0], sd.args[1], sd.args[2]);
}
return 0;
}
PROG(SYS__NR_mmap)(struct pt_regs *ctx)
{
char fmt[] = "mmap\n";
bpf_trace_printk(fmt, sizeof(fmt));
return 0;
}
char _license[] SEC("license") = "GPL";
u32 _version SEC("version") = LINUX_VERSION_CODE;
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