在没有--privileged的docker容器内使用perf [英] Use perf inside a docker container without --privileged

问题描述

我正在尝试使用Docker容器内的perf工具来记录给定命令.

kernel.perf_event_paranoid设置为1，但是当我不放置--privileged标志时，容器的行为就像在第2位一样.

我可以使用--privileged，但是我在perf上运行的代码不受信任，如果我可以允许使用perf工具承担一点安全风险，那么对容器授予特权似乎是另一种风险.

还有其他在容器内使用perf的方法吗?

~$ docker version
Client:
 Version:      17.03.1-ce
 API version:  1.27
 Go version:   go1.7.5
 Git commit:   7392c3b/17.03.1-ce
 Built:        Tue May 30 17:59:44 2017
 OS/Arch:      linux/amd64

Server:
 Version:      17.03.1-ce
 API version:  1.27 (minimum version 1.12)
 Go version:   go1.7.5
 Git commit:   7392c3b/17.03.1-ce
 Built:        Tue May 30 17:59:44 2017
 OS/Arch:      linux/amd64
 Experimental: false

~$ cat /proc/sys/kernel/perf_event_paranoid
1
~$ perf record ./my-executable
perf_event_open(..., PERF_FLAG_FD_CLOEXEC) failed with unexpected error 1 (Operation not permitted)
perf_event_open(..., 0) failed unexpectedly with error 1 (Operation not permitted)
Error:
You may not have permission to collect stats.
Consider tweaking /proc/sys/kernel/perf_event_paranoid:
 -1 - Not paranoid at all
  0 - Disallow raw tracepoint access for unpriv
  1 - Disallow cpu events for unpriv
  2 - Disallow kernel profiling for unpriv

解决方案

经过研究，问题不在于perf_event_paranoid，而是因为perf_event_open(syscall)已在docker中被列入黑名单: https://docs.docker.com/engine/security/seccomp/"Docker v17.06:适用于Docker的Seccomp安全配置文件"

被默认配置文件阻止的大量系统调用

perf_event_open跟踪/分析系统调用，这可能会泄漏主机上的许多信息.

为此，我的第一个解决方法是拥有一个脚本，该脚本可以下载官方seccomp文件 https://github.com/moby/moby/blob/master/profiles/seccomp/default.json ，并将perf_event_open添加到白名单的系统调用列表中.

然后我用--security-opt seccomp=my-seccomp.json

启动docker

I am trying to use the perf tool inside a Docker container to record a given command.

kernel.perf_event_paranoid is set to 1, but the container behaves just as if it where 2, when I don't put the --privileged flag.

I could use --privileged, but the code I am running perf on is not trusted and if I am OK with taking a slight security risk by allowing perf tool, giving privileged rights on the container seems a different level of risk.

Is there any other way to use perf inside the container?

~$ docker version
Client:
 Version:      17.03.1-ce
 API version:  1.27
 Go version:   go1.7.5
 Git commit:   7392c3b/17.03.1-ce
 Built:        Tue May 30 17:59:44 2017
 OS/Arch:      linux/amd64

Server:
 Version:      17.03.1-ce
 API version:  1.27 (minimum version 1.12)
 Go version:   go1.7.5
 Git commit:   7392c3b/17.03.1-ce
 Built:        Tue May 30 17:59:44 2017
 OS/Arch:      linux/amd64
 Experimental: false

~$ cat /proc/sys/kernel/perf_event_paranoid
1
~$ perf record ./my-executable
perf_event_open(..., PERF_FLAG_FD_CLOEXEC) failed with unexpected error 1 (Operation not permitted)
perf_event_open(..., 0) failed unexpectedly with error 1 (Operation not permitted)
Error:
You may not have permission to collect stats.
Consider tweaking /proc/sys/kernel/perf_event_paranoid:
 -1 - Not paranoid at all
  0 - Disallow raw tracepoint access for unpriv
  1 - Disallow cpu events for unpriv
  2 - Disallow kernel profiling for unpriv

解决方案

After some research, the problem is not with the perf_event_paranoid, but with the fact that perf_event_open (syscall) has been blacklisted in docker: https://docs.docker.com/engine/security/seccomp/ "Docker v17.06: Seccomp security profiles for Docker"

Significant syscalls blocked by the default profile

perf_event_open Tracing/profiling syscall, which could leak a lot of information on the host.

My first work-around for this is to have a script that downloads the official seccomp file https://github.com/moby/moby/blob/master/profiles/seccomp/default.json, and adds perf_event_open to the list of white-listed syscalls.

I then start docker with --security-opt seccomp=my-seccomp.json

这篇关于在没有--privileged的docker容器内使用perf的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！