error dwarf therapist / savegamefolder with kubuntu about df-lnp-installer

[andrewd18]

Got it. The "ptrace attach: operation not permitted" is good news, actually, because that means we've found the source of the problem. :)

In recent versions of Ubuntu, the Ubuntu kernel team turned on a kernel feature called "ptrace protection". This prevents an application to connect to another one and read its memory. See https://wiki.ubuntu.com/SecurityTeam/Roadmap/KernelHardening#ptrace%20Protection

Unfortunately, attaching to the memory of another program is exactly what DwarfTherapist does.

You'll need to manually disable ptrace protection on your machine. The following command should do it:

sudo echo 0 > /proc/sys/kernel/yama/ptrace_scope

[andrewd18]

I think you're reporting two different issues here.

1. The "Open Savegames Folder" button in the LNP launcher does not work. This is a known issue with the LNP launcher. See "WARNING" in the LNP launcher thread. http://www.bay12forums.com/smf/index.php?topic=124613
2. Dwarf Therapist complains that it cannot connect to Dwarf Fortress. Dwarf Therapist requires that you have a region loaded and running. It will not be able to find DF from the main menu screen. Please try loading a game and clicking the connect button in Dwarf Therapist.

[andrewd18]

Do you get a message in the command line output from LNP saying "ptrace attach: operation not permitted"?

[Hmpfmg]

here's the error message.

[Hmpfmg]

oh.. just seen the command line output "ptrace attach: operation not permitted"

[Hmpfmg]

You got it! You'r the best! :)

echo 0 | sudo tee /proc/sys/kernel/yama/ptrace_scope

work's fine for me!

[andrewd18]

Fantastic. I'm going to add a step in the installer to check for ptrace_scope and I'll reuse your command in the documentation. I'll close this once that check gets added.

Thanks for the report.

[andrewd18]

Resolved in 0.3.0 branch as of commit 9cf3a8c.

[aalbaugh]

Note for anyone running Ubuntu (not sure what versions, i am using 12.10 Quantal). The above solutions will not work, because the /proc/sys/kernel/yama/... folder seems to be protected. I was unable to use sudo to make any changes via a straight echo > 0 ... The second solution, piping output from echo to a sudo-privileged 'tee' did, in fact work. I'm not sure if the change will be permanent, however.

A previous attempt, made by first 'sudo su' -ing to root did not stay.

[andrewd18]

The second solution, piping output from echo to a sudo-privileged 'tee' did, in fact work. I'm not sure if the change will be permanent, however.

/proc is managed by the kernel and you'd be able to find out if the option stayed by rebooting.

[aalbaugh]

yeah, i'll check after class.

[andrewd18]

I'd bet it won't persist. On the other hand I bet this will work:

echo "kernel.yama.ptrace_scope = 0" | sudo tee /etc/sysctl.d/10-ptrace.conf

[aalbaugh]

you're correct, it did not persist.

The change you suggested should work, will get back to you once I know for sure.

[andrewd18]

There is now a wiki page talking about this, and 0.3.0 will look for and inform the user if ptrace protection is turned on. Closing the ticket.

https://github.com/andrewd18/df-lnp-installer/wiki/Dwarf-Therapist-Cannot-Connect-to-Dwarf-Fortress