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CVE-2019-5736: runc container breakout

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Re: CVE-2019-5736: runc container breakout

#101

Earlier quoted context omitted.

As far as I understand, EKS doesn't support PodSecurityPolicy yet so any user that can launch a pod can trivially root the host via host mounts already. This surprisingly isn't clearly documented.

ECS doesn't have a top level resource called "PodSecurityPolicy" but we do provide task level configuration options for all the major settings that you would normally put in your pod security policy, including including adding and dropping capabilities, privileged or unprivileged mode, docker security options for controlling SELinux or AppArmor, ulimits, sysctl settings, among others. You can find all these configura…

I'm referring to EKS here not ECS. EKS doesn't yet enable the PodSecurityPolicy admission controller, so any user that can launch a pod via EKS can root the EKS cluster regardless of RBAC rules. The main ask here is to just find a way to enable PodSecurityPolicy admission controller so that secure multi-user EKS clusters are possible like ECS.

Re: CVE-2019-5736: runc container breakout

#102
post #96

The vulnerability description seems to be lacking an explanation why the /proc/$PID/exe symlink is so special and why using the #!/proc/self/exe hashbang will work while using #!/usr/sbin/runc probably won't. Am I right that the proc filesystem in proc_exe_link() fills the file_operations struct in a way that causes open() not to go through a dereferencing procedure using the filesystem but just open the file used to…

So I will answer myself. Experiments suggest it is like that: https://www.reddit.com/r/linux/comments/apmptq/cve20195736_r...
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