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I accidentally deleted su once. Not directly; I was cleaning up a botched upgrade and uninstalled linux-utils. Sudo was still there but couldn't do anything u

I accidentally deleted su once. Not directly; I was cleaning up a botched upgrade and uninstalled linux-utils. Sudo was still there but couldn't do anything useful. This was on a qnap NAS device so eventually I used an arduino as a USB-to-serial-to-JTAG to manipulate the boot parameters, boot into single user mode, and edit the sudoers file.

dekhn 3y ago
In college, many aeons ago, I bought a used Sun workstation (mainly for the copy of FrameMaker on the machine). At some point I was trying to clean up the root filesystem and deleted the root shell (I can't remember the details but I think there were two shells, one used to boot the system, and one for the user shell). That's how I learned that SunOS machines at the time had an extensive set of features for booting the machine (like, a built in EFI shell) and providing kernel params, so I was able to finally boot into the machine by telling the kernel to launch the user shell, which was enough to boot the machine to user space. The SunOS machines also could do pretty much everything over serial- including installing an entire OS.
vbezhenar 3y ago
ssh root@localhost suid bit is considered harmful
- pxeger1 3y ago
  Why considered harmful? Connecting to a daemon running as root still relies on the security of the daemon.
  - vbezhenar 3y ago
    Because it's security escape hatch. It's not needed. Suid programs caused many vulnerabilities. There must not be a way to get more privileges, only less.
- kazinator 3y ago
  You can do that if you had the forethought to edit your /etc/securetty file before nuking su, to allow root logins on the ptys used by sshd. If not, logging in on a physical console would work or rebooting to single either mode or whatever.
sebazzz 3y ago
I updated my arch installation once, but an incompatible version of glibc was installed. Unfortunately, pacman, which you use for all packages, links itself to glibc and refused to run. Directly attempting to replace the glibc binaries caused a kernel panic. I had to reboot and chroot from a recovery disk to my installation and upgrade/repair glibc and pacman there.

dekhn 3y ago

In college, many aeons ago, I bought a used Sun workstation (mainly for the copy of FrameMaker on the machine). At some point I was trying to clean up the root filesystem and deleted the root shell (I can't remember the details but I think there were two shells, one used to boot the system, and one for the user shell). That's how I learned that SunOS machines at the time had an extensive set of features for booting the machine (like, a built in EFI shell) and providing kernel params, so I was able to finally boot into the machine by telling the kernel to launch the user shell, which was enough to boot the machine to user space. The SunOS machines also could do pretty much everything over serial- including installing an entire OS.

vbezhenar 3y ago

ssh root@localhost suid bit is considered harmful

pxeger1 3y ago
Why considered harmful? Connecting to a daemon running as root still relies on the security of the daemon.
- vbezhenar 3y ago
  Because it's security escape hatch. It's not needed. Suid programs caused many vulnerabilities. There must not be a way to get more privileges, only less.
kazinator 3y ago
You can do that if you had the forethought to edit your /etc/securetty file before nuking su, to allow root logins on the ptys used by sshd. If not, logging in on a physical console would work or rebooting to single either mode or whatever.

sebazzz 3y ago

I updated my arch installation once, but an incompatible version of glibc was installed. Unfortunately, pacman, which you use for all packages, links itself to glibc and refused to run. Directly attempting to replace the glibc binaries caused a kernel panic. I had to reboot and chroot from a recovery disk to my installation and upgrade/repair glibc and pacman there.