tracex5_kern.c 2.01 KB
Newer Older
1 2 3 4 5 6 7 8 9 10
/* 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>
11
#include <uapi/linux/unistd.h>
12
#include "syscall_nrs.h"
13 14 15 16 17 18 19 20
#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),
21 22 23
#ifdef __mips__
	.max_entries = 6000, /* MIPS n64 syscalls start at 5000 */
#else
24
	.max_entries = 1024,
25
#endif
26 27
};

28
SEC("kprobe/__seccomp_filter")
29 30
int bpf_prog1(struct pt_regs *ctx)
{
31
	int sc_nr = (int)PT_REGS_PARM1(ctx);
32 33

	/* dispatch into next BPF program depending on syscall number */
34
	bpf_tail_call(ctx, &progs, sc_nr);
35 36

	/* fall through -> unknown syscall */
37
	if (sc_nr >= __NR_getuid && sc_nr <= __NR_getsid) {
38
		char fmt[] = "syscall=%d (one of get/set uid/pid/gid)\n";
39
		bpf_trace_printk(fmt, sizeof(fmt), sc_nr);
40 41 42 43 44
	}
	return 0;
}

/* we jump here when syscall number == __NR_write */
45
PROG(SYS__NR_write)(struct pt_regs *ctx)
46
{
47
	struct seccomp_data sd;
48

49
	bpf_probe_read(&sd, sizeof(sd), (void *)PT_REGS_PARM2(ctx));
50 51 52 53 54 55 56 57
	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;
}

58
PROG(SYS__NR_read)(struct pt_regs *ctx)
59
{
60
	struct seccomp_data sd;
61

62
	bpf_probe_read(&sd, sizeof(sd), (void *)PT_REGS_PARM2(ctx));
63 64 65 66 67 68 69 70
	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;
}

71
PROG(SYS__NR_mmap)(struct pt_regs *ctx)
72 73 74 75 76 77 78 79
{
	char fmt[] = "mmap\n";
	bpf_trace_printk(fmt, sizeof(fmt));
	return 0;
}

char _license[] SEC("license") = "GPL";
u32 _version SEC("version") = LINUX_VERSION_CODE;