megassh problems

[pfuntner]

I think I've seen a problem with megassh in the past and tried to fix it but it's still a problem. Sometimes, output from a host is overlooked somehow:

[ubuntu@pfuntner-20221025 packer-examples master]$ ansible-hosts
Host            User      Address         Distro         Up time      Kernel                        Arch    Pkgmgr  Svcmgr
aws-almalinux8  ec2-user  3.87.162.186    AlmaLinux 8.7  00-00:01:54  4.18.0-425.3.1.el8.x86_64     x86_64  dnf     systemd
aws-rhel8       ec2-user  3.88.9.145      RedHat 8.7     00-00:02:29  4.18.0-425.3.1.el8.x86_64     x86_64  dnf     systemd
gcp-almalinux8  jpfuntne  34.148.128.162  AlmaLinux 8.7  00-00:01:31  4.18.0-425.13.1.el8_7.x86_64  x86_64  dnf     systemd
gcp-rhel8       jpfuntne  35.227.62.101   RedHat 8.7     00-00:02:29  4.18.0-425.13.1.el8_7.x86_64  x86_64  dnf     systemd
[ubuntu@pfuntner-20221025 packer-examples master]$ ^Cw-instances almalinux8
[ubuntu@pfuntner-20221025 packer-examples master]$ megassh all cat /etc/crypto-policies/config
aws-almalinux8: DEFAULT


gcp-almalinux8: DEFAULT


[ubuntu@pfuntner-20221025 packer-examples master]$ megassh all -- ls /etc/crypto-policies/config\; cat /etc/crypto-policies/config
aws-almalinux8: /etc/crypto-policies/config
aws-almalinux8: DEFAULT

aws-rhel8: /etc/crypto-policies/config
aws-rhel8: DEFAULT

gcp-almalinux8: /etc/crypto-policies/config
gcp-almalinux8: DEFAULT

gcp-rhel8: /etc/crypto-policies/config
gcp-rhel8: DEFAULT

[ubuntu@pfuntner-20221025 packer-examples master]$ megassh all -- ls -ld /etc/crypto-policies/config\; cat /etc/crypto-policies/config
aws-almalinux8: -rw-r--r--. 1 root root 8 Nov 10 21:05 /etc/crypto-policies/config
aws-almalinux8: DEFAULT

aws-rhel8: -rw-r--r--. 1 root root 8 Nov  3 10:50 /etc/crypto-policies/config
aws-rhel8: DEFAULT



[ubuntu@pfuntner-20221025 packer-examples master]$ megassh all -- ls -ld /etc/crypto-policies/config\; cat /etc/crypto-policies/config
aws-almalinux8: -rw-r--r--. 1 root root 8 Nov 10 21:05 /etc/crypto-policies/config
aws-almalinux8: DEFAULT

aws-rhel8: -rw-r--r--. 1 root root 8 Nov  3 10:50 /etc/crypto-policies/config
aws-rhel8: DEFAULT

gcp-almalinux8: -rw-r--r--. 1 root root 8 Mar  6 18:24 /etc/crypto-policies/config
gcp-almalinux8: DEFAULT


[ubuntu@pfuntner-20221025 packer-examples master]$

[pfuntner]

I basically did a complete fresh rewrite of the command in babd476 and it seems to be working great.

For each host:

• A thread is created that creates the new process
• A second thread is created to read stdout in a non-blocking manner
• A third thread is created to read stderr in a non-blocking manner
• The second and third threads end when they exhaust their respective stream, regardless of if the process finished
• The first thread ends when the second and third threads end and the process has an exit status

I reused the idea of using base64 encoding to protect arbitrary commands but I think it's really only needed when you escalate to root so I had it automatically encode when you escalate. There's no longer an independent encoding option.