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5bacd780 AS |
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 "bpf_helpers.h" | |
12 | ||
13 | #define PROG(F) SEC("kprobe/"__stringify(F)) int bpf_func_##F | |
14 | ||
15 | struct bpf_map_def SEC("maps") progs = { | |
16 | .type = BPF_MAP_TYPE_PROG_ARRAY, | |
17 | .key_size = sizeof(u32), | |
18 | .value_size = sizeof(u32), | |
19 | .max_entries = 1024, | |
20 | }; | |
21 | ||
973d94d8 | 22 | SEC("kprobe/__seccomp_filter") |
5bacd780 AS |
23 | int bpf_prog1(struct pt_regs *ctx) |
24 | { | |
973d94d8 | 25 | int sc_nr = (int)PT_REGS_PARM1(ctx); |
5bacd780 AS |
26 | |
27 | /* dispatch into next BPF program depending on syscall number */ | |
973d94d8 | 28 | bpf_tail_call(ctx, &progs, sc_nr); |
5bacd780 AS |
29 | |
30 | /* fall through -> unknown syscall */ | |
973d94d8 | 31 | if (sc_nr >= __NR_getuid && sc_nr <= __NR_getsid) { |
5bacd780 | 32 | char fmt[] = "syscall=%d (one of get/set uid/pid/gid)\n"; |
973d94d8 | 33 | bpf_trace_printk(fmt, sizeof(fmt), sc_nr); |
5bacd780 AS |
34 | } |
35 | return 0; | |
36 | } | |
37 | ||
38 | /* we jump here when syscall number == __NR_write */ | |
39 | PROG(__NR_write)(struct pt_regs *ctx) | |
40 | { | |
02413cab | 41 | struct seccomp_data sd; |
5bacd780 | 42 | |
973d94d8 | 43 | bpf_probe_read(&sd, sizeof(sd), (void *)PT_REGS_PARM2(ctx)); |
5bacd780 AS |
44 | if (sd.args[2] == 512) { |
45 | char fmt[] = "write(fd=%d, buf=%p, size=%d)\n"; | |
46 | bpf_trace_printk(fmt, sizeof(fmt), | |
47 | sd.args[0], sd.args[1], sd.args[2]); | |
48 | } | |
49 | return 0; | |
50 | } | |
51 | ||
52 | PROG(__NR_read)(struct pt_regs *ctx) | |
53 | { | |
02413cab | 54 | struct seccomp_data sd; |
5bacd780 | 55 | |
973d94d8 | 56 | bpf_probe_read(&sd, sizeof(sd), (void *)PT_REGS_PARM2(ctx)); |
5bacd780 AS |
57 | if (sd.args[2] > 128 && sd.args[2] <= 1024) { |
58 | char fmt[] = "read(fd=%d, buf=%p, size=%d)\n"; | |
59 | bpf_trace_printk(fmt, sizeof(fmt), | |
60 | sd.args[0], sd.args[1], sd.args[2]); | |
61 | } | |
62 | return 0; | |
63 | } | |
64 | ||
65 | PROG(__NR_mmap)(struct pt_regs *ctx) | |
66 | { | |
67 | char fmt[] = "mmap\n"; | |
68 | bpf_trace_printk(fmt, sizeof(fmt)); | |
69 | return 0; | |
70 | } | |
71 | ||
72 | char _license[] SEC("license") = "GPL"; | |
73 | u32 _version SEC("version") = LINUX_VERSION_CODE; |