Use perf inside a docker container without --privileged

问题

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

回答1:

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

回答2:

Run docker with --cap-add SYS_ADMIN

来源：https://stackoverflow.com/questions/44745987/use-perf-inside-a-docker-container-without-privileged

标签

Linux

Docker

privileges

perf