tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/* Copyright (c) 2015 PLUMgrid, http://plumgrid.com
2 *
3 * This program is free software; you can redistribute it and/or
4 * modify it under the terms of version 2 of the GNU General Public
5 * License as published by the Free Software Foundation.
6 */
7#include <linux/ptrace.h>
8#include <linux/version.h>
9#include <uapi/linux/bpf.h>
10#include <uapi/linux/seccomp.h>
11#include <uapi/linux/unistd.h>
12#include "syscall_nrs.h"
13#include "bpf_helpers.h"
14
15#define PROG(F) SEC("kprobe/"__stringify(F)) int bpf_func_##F
16
17struct bpf_map_def SEC("maps") progs = {
18 .type = BPF_MAP_TYPE_PROG_ARRAY,
19 .key_size = sizeof(u32),
20 .value_size = sizeof(u32),
21#ifdef __mips__
22 .max_entries = 6000, /* MIPS n64 syscalls start at 5000 */
23#else
24 .max_entries = 1024,
25#endif
26};
27
28SEC("kprobe/__seccomp_filter")
29int bpf_prog1(struct pt_regs *ctx)
30{
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 return 0;
42}
43
44/* we jump here when syscall number == __NR_write */
45PROG(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 if (sd.args[2] == 512) {
51 char fmt[] = "write(fd=%d, buf=%p, size=%d)\n";
52 bpf_trace_printk(fmt, sizeof(fmt),
53 sd.args[0], sd.args[1], sd.args[2]);
54 }
55 return 0;
56}
57
58PROG(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 if (sd.args[2] > 128 && sd.args[2] <= 1024) {
64 char fmt[] = "read(fd=%d, buf=%p, size=%d)\n";
65 bpf_trace_printk(fmt, sizeof(fmt),
66 sd.args[0], sd.args[1], sd.args[2]);
67 }
68 return 0;
69}
70
71#ifdef __NR_mmap2
72PROG(SYS__NR_mmap2)(struct pt_regs *ctx)
73{
74 char fmt[] = "mmap2\n";
75
76 bpf_trace_printk(fmt, sizeof(fmt));
77 return 0;
78}
79#endif
80
81#ifdef __NR_mmap
82PROG(SYS__NR_mmap)(struct pt_regs *ctx)
83{
84 char fmt[] = "mmap\n";
85
86 bpf_trace_printk(fmt, sizeof(fmt));
87 return 0;
88}
89#endif
90
91char _license[] SEC("license") = "GPL";
92u32 _version SEC("version") = LINUX_VERSION_CODE;