| Alexei Starovoitov | 5bacd78 | 2015-05-19 16:59:05 -0700 | [diff] [blame] | 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 | |
| 22 | SEC("kprobe/seccomp_phase1") |
| 23 | int bpf_prog1(struct pt_regs *ctx) |
| 24 | { |
| 25 | struct seccomp_data sd = {}; |
| 26 | |
| 27 | bpf_probe_read(&sd, sizeof(sd), (void *)ctx->di); |
| 28 | |
| 29 | /* dispatch into next BPF program depending on syscall number */ |
| 30 | bpf_tail_call(ctx, &progs, sd.nr); |
| 31 | |
| 32 | /* fall through -> unknown syscall */ |
| 33 | if (sd.nr >= __NR_getuid && sd.nr <= __NR_getsid) { |
| 34 | char fmt[] = "syscall=%d (one of get/set uid/pid/gid)\n"; |
| 35 | bpf_trace_printk(fmt, sizeof(fmt), sd.nr); |
| 36 | } |
| 37 | return 0; |
| 38 | } |
| 39 | |
| 40 | /* we jump here when syscall number == __NR_write */ |
| 41 | PROG(__NR_write)(struct pt_regs *ctx) |
| 42 | { |
| 43 | struct seccomp_data sd = {}; |
| 44 | |
| 45 | bpf_probe_read(&sd, sizeof(sd), (void *)ctx->di); |
| 46 | if (sd.args[2] == 512) { |
| 47 | char fmt[] = "write(fd=%d, buf=%p, size=%d)\n"; |
| 48 | bpf_trace_printk(fmt, sizeof(fmt), |
| 49 | sd.args[0], sd.args[1], sd.args[2]); |
| 50 | } |
| 51 | return 0; |
| 52 | } |
| 53 | |
| 54 | PROG(__NR_read)(struct pt_regs *ctx) |
| 55 | { |
| 56 | struct seccomp_data sd = {}; |
| 57 | |
| 58 | bpf_probe_read(&sd, sizeof(sd), (void *)ctx->di); |
| 59 | if (sd.args[2] > 128 && sd.args[2] <= 1024) { |
| 60 | char fmt[] = "read(fd=%d, buf=%p, size=%d)\n"; |
| 61 | bpf_trace_printk(fmt, sizeof(fmt), |
| 62 | sd.args[0], sd.args[1], sd.args[2]); |
| 63 | } |
| 64 | return 0; |
| 65 | } |
| 66 | |
| 67 | PROG(__NR_mmap)(struct pt_regs *ctx) |
| 68 | { |
| 69 | char fmt[] = "mmap\n"; |
| 70 | bpf_trace_printk(fmt, sizeof(fmt)); |
| 71 | return 0; |
| 72 | } |
| 73 | |
| 74 | char _license[] SEC("license") = "GPL"; |
| 75 | u32 _version SEC("version") = LINUX_VERSION_CODE; |