Description of problem:

Due to the way various container runtimes set up seccomp filters, libseccomp needs to be updated for new system calls even though the host kernel does not support them. Otherwise, it is not possible to produce an ENOSYS error for them.

Version-Release number of selected component (if applicable):

libseccomp-2.3.1-4.el7.x86_64

How reproducible:

Always.

Steps to Reproduce:

Install Docker CE, in these package versions:

  containerd.io-1.4.3-3.1.el7.x86_64
  libseccomp-2.3.1-4.el7.x86_64
  docker-ce-rootless-extras-20.10.1-3.el7.x86_64
  docker-ce-20.10.1-3.el7.x86_64
  docker-ce-cli-20.10.1-3.el7.x86_64
  container-selinux-2.119.2-1.911c772.el7_8.noarch

This version has faccessat2 support on the Docker CE side.

Then run:

docker run fedora:rawhide /bin/bash -c "yum update -y glibc; bash -c 'test -r /tmp; echo \$?'"

Quoting is a bit tricky here. The inner bash is needed to pick up the new glibc.

Actual results:

1

(faccessat2 return EPERM.)

Expected results:

0

(faccessat2 return ENOSYS, and faccessat fallback is used.)


Additional info:

I rebuild libseccomp 2.5.1 from the upstream sources and verified that it fixes the seccomp filters. But knowledge of the new system calls can likely be backported separately.