1*4882a593Smuzhiyun /* Copyright (c) 2015 PLUMgrid, http://plumgrid.com
2*4882a593Smuzhiyun *
3*4882a593Smuzhiyun * This program is free software; you can redistribute it and/or
4*4882a593Smuzhiyun * modify it under the terms of version 2 of the GNU General Public
5*4882a593Smuzhiyun * License as published by the Free Software Foundation.
6*4882a593Smuzhiyun */
7*4882a593Smuzhiyun #include <linux/ptrace.h>
8*4882a593Smuzhiyun #include <linux/version.h>
9*4882a593Smuzhiyun #include <uapi/linux/bpf.h>
10*4882a593Smuzhiyun #include <uapi/linux/seccomp.h>
11*4882a593Smuzhiyun #include <uapi/linux/unistd.h>
12*4882a593Smuzhiyun #include "syscall_nrs.h"
13*4882a593Smuzhiyun #include <bpf/bpf_helpers.h>
14*4882a593Smuzhiyun #include <bpf/bpf_tracing.h>
15*4882a593Smuzhiyun
16*4882a593Smuzhiyun #define PROG(F) SEC("kprobe/"__stringify(F)) int bpf_func_##F
17*4882a593Smuzhiyun
18*4882a593Smuzhiyun struct {
19*4882a593Smuzhiyun __uint(type, BPF_MAP_TYPE_PROG_ARRAY);
20*4882a593Smuzhiyun __uint(key_size, sizeof(u32));
21*4882a593Smuzhiyun __uint(value_size, sizeof(u32));
22*4882a593Smuzhiyun #ifdef __mips__
23*4882a593Smuzhiyun __uint(max_entries, 6000); /* MIPS n64 syscalls start at 5000 */
24*4882a593Smuzhiyun #else
25*4882a593Smuzhiyun __uint(max_entries, 1024);
26*4882a593Smuzhiyun #endif
27*4882a593Smuzhiyun } progs SEC(".maps");
28*4882a593Smuzhiyun
29*4882a593Smuzhiyun SEC("kprobe/__seccomp_filter")
bpf_prog1(struct pt_regs * ctx)30*4882a593Smuzhiyun int bpf_prog1(struct pt_regs *ctx)
31*4882a593Smuzhiyun {
32*4882a593Smuzhiyun int sc_nr = (int)PT_REGS_PARM1(ctx);
33*4882a593Smuzhiyun
34*4882a593Smuzhiyun /* dispatch into next BPF program depending on syscall number */
35*4882a593Smuzhiyun bpf_tail_call(ctx, &progs, sc_nr);
36*4882a593Smuzhiyun
37*4882a593Smuzhiyun /* fall through -> unknown syscall */
38*4882a593Smuzhiyun if (sc_nr >= __NR_getuid && sc_nr <= __NR_getsid) {
39*4882a593Smuzhiyun char fmt[] = "syscall=%d (one of get/set uid/pid/gid)\n";
40*4882a593Smuzhiyun bpf_trace_printk(fmt, sizeof(fmt), sc_nr);
41*4882a593Smuzhiyun }
42*4882a593Smuzhiyun return 0;
43*4882a593Smuzhiyun }
44*4882a593Smuzhiyun
45*4882a593Smuzhiyun /* we jump here when syscall number == __NR_write */
PROG(SYS__NR_write)46*4882a593Smuzhiyun PROG(SYS__NR_write)(struct pt_regs *ctx)
47*4882a593Smuzhiyun {
48*4882a593Smuzhiyun struct seccomp_data sd;
49*4882a593Smuzhiyun
50*4882a593Smuzhiyun bpf_probe_read_kernel(&sd, sizeof(sd), (void *)PT_REGS_PARM2(ctx));
51*4882a593Smuzhiyun if (sd.args[2] == 512) {
52*4882a593Smuzhiyun char fmt[] = "write(fd=%d, buf=%p, size=%d)\n";
53*4882a593Smuzhiyun bpf_trace_printk(fmt, sizeof(fmt),
54*4882a593Smuzhiyun sd.args[0], sd.args[1], sd.args[2]);
55*4882a593Smuzhiyun }
56*4882a593Smuzhiyun return 0;
57*4882a593Smuzhiyun }
58*4882a593Smuzhiyun
PROG(SYS__NR_read)59*4882a593Smuzhiyun PROG(SYS__NR_read)(struct pt_regs *ctx)
60*4882a593Smuzhiyun {
61*4882a593Smuzhiyun struct seccomp_data sd;
62*4882a593Smuzhiyun
63*4882a593Smuzhiyun bpf_probe_read_kernel(&sd, sizeof(sd), (void *)PT_REGS_PARM2(ctx));
64*4882a593Smuzhiyun if (sd.args[2] > 128 && sd.args[2] <= 1024) {
65*4882a593Smuzhiyun char fmt[] = "read(fd=%d, buf=%p, size=%d)\n";
66*4882a593Smuzhiyun bpf_trace_printk(fmt, sizeof(fmt),
67*4882a593Smuzhiyun sd.args[0], sd.args[1], sd.args[2]);
68*4882a593Smuzhiyun }
69*4882a593Smuzhiyun return 0;
70*4882a593Smuzhiyun }
71*4882a593Smuzhiyun
72*4882a593Smuzhiyun #ifdef __NR_mmap2
PROG(SYS__NR_mmap2)73*4882a593Smuzhiyun PROG(SYS__NR_mmap2)(struct pt_regs *ctx)
74*4882a593Smuzhiyun {
75*4882a593Smuzhiyun char fmt[] = "mmap2\n";
76*4882a593Smuzhiyun
77*4882a593Smuzhiyun bpf_trace_printk(fmt, sizeof(fmt));
78*4882a593Smuzhiyun return 0;
79*4882a593Smuzhiyun }
80*4882a593Smuzhiyun #endif
81*4882a593Smuzhiyun
82*4882a593Smuzhiyun #ifdef __NR_mmap
PROG(SYS__NR_mmap)83*4882a593Smuzhiyun PROG(SYS__NR_mmap)(struct pt_regs *ctx)
84*4882a593Smuzhiyun {
85*4882a593Smuzhiyun char fmt[] = "mmap\n";
86*4882a593Smuzhiyun
87*4882a593Smuzhiyun bpf_trace_printk(fmt, sizeof(fmt));
88*4882a593Smuzhiyun return 0;
89*4882a593Smuzhiyun }
90*4882a593Smuzhiyun #endif
91*4882a593Smuzhiyun
92*4882a593Smuzhiyun char _license[] SEC("license") = "GPL";
93*4882a593Smuzhiyun u32 _version SEC("version") = LINUX_VERSION_CODE;
94