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" ) |
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 */ |
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 | |
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 |
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 |
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 | |