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 "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) #x
16 #define PROG(F) SEC("kprobe/"__stringify(F)) int bpf_func_##F
17
18 struct {
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 #else
25 __uint(max_entries, 1024);
26 #endif
27 } progs SEC(".maps");
28
29 SEC("kprobe/__seccomp_filter")
bpf_prog1(struct pt_regs * ctx)30 int 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 */
PROG(SYS__NR_write)46 PROG(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
PROG(SYS__NR_read)59 PROG(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_mmap2
PROG(SYS__NR_mmap2)73 PROG(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 #endif
81
82 #ifdef __NR_mmap
PROG(SYS__NR_mmap)83 PROG(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 #endif
91
92 char _license[] SEC("license") = "GPL";
93 u32 _version SEC("version") = LINUX_VERSION_CODE;
94