无法在 Docker 容器中执行二进制文件（“不允许操作”）

Question

问题

我正在构建一个 Docker 容器（基于 RHEL），其中包含来自第三方存储库的自定义二进制文件。在容器中执行二进制文件时，我收到一个不起眼的错误：“ Operation not permitted”。

分析

Dockerfile

Dockerfile 相当简单。

FROM dockerregistry.example.com/rhel7:latest

RUN yum -y install \
    curl \
    custom-package && \
    curl -Lsq https://github.com/Yelp/dumb-init/releases/download/v1.2.0/dumb-init_1.2.0_amd64 > /sbin/dumb-init && \
    chmod 755 /sbin/dumb-init && \
    yum clean all

ADD custom-package.conf /etc/custom-package/custom-package.conf

ENTRYPOINT ["/sbin/dumb-init", "--"]
CMD ["/usr/local/custom-package/bin/custom-package", "--config", "/etc/custom-package/custom-package.conf"]

塑造形象

我使用以下命令在我的工作站上构建并输入容器。

$ docker build -t custom-package:v1 .
$ docker run --security-opt seccomp:unconfined -d custom-package:v1 tail -f /dev/null
$ docker exec -it <image ID> /bin/bash

“不允许操作”

一旦我进入图像，如果我尝试执行二进制文件，我会收到一个极其无用的错误。运行strace也会产生令人困惑的输出。在检查文件权限和元数据时，似乎没问题。

# /usr/local/telegraf/bin/telegraf
bash: /usr/local/telegraf/bin/telegraf: Operation not permitted

# strace -f /usr/local/telegraf/bin/telegraf
execve("/usr/local/telegraf/bin/telegraf", ["/usr/local/telegraf/bin/telegraf"], [/* 17 vars */]) = -1 EPERM (Operation not permitted)
write(2, "strace: exec: Operation not perm"..., 38strace: exec: Operation not permitted
) = 38
exit_group(1)                           = ?
+++ exited with 1 +++

# ls -l /usr/local/telegraf/bin/telegraf    
-rwxr-xr-x 1 telegraf telegraf 38664736 Jun  3 15:41 /usr/local/telegraf/bin/telegraf

# getcap -v /usr/local/telegraf/bin/telegraf
/usr/local/telegraf/bin/telegraf = cap_sys_rawio+ep

我无法收集足够的信息来调试我的容器以及可执行二进制文件无法工作的原因。是否有什么明显错误的地方或者我会收到这样的无用错误的原因？

谢谢！

Answer 1

SYS_RAWIO 功能需要--privileged访问设备的选项。请参阅功能(7)。

http://man7.org/linux/man-pages/man7/capability.7.html

   CAP_SYS_RAWIO
          * Perform I/O port operations (iopl(2) and ioperm(2));
          * access /proc/kcore;
          * employ the FIBMAP ioctl(2) operation;
          * open devices for accessing x86 model-specific registers (MSRs, see msr(4))
          * update /proc/sys/vm/mmap_min_addr;
          * create memory mappings at addresses below the value specified by /proc/sys/vm/mmap_min_addr;
          * map files in /proc/bus/pci;
          * open /dev/mem and /dev/kmem;
          * perform various SCSI device commands;
          * perform certain operations on hpsa(4) and cciss(4) devices;
          * perform a range of device-specific operations on other devices.