Ubuntu 10.10 kernel hardening, ptrace protection, and GDB attaching

Today I happened to try to use the gdb debugger to try to attach to an already-running process, and failed:

ptrace: Operation not permitted.

After a certain amount of bashing-of-head-against-wall and cursing-of-frustration-didn't-this-work-before activities, I did a bit of web searching, and found:

• gdb attach fails with ptrace: Operation not permitted


• SecurityTeam/Roadmap/KernelHardening


• Fixing problems on new Ubuntu version "Maverick Meerkat"

I'm not completely sure what to make of this, but the suggested workaround:

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

(executed as root) seems to have done the trick, for now.

If this happened to be your particular nightmare as well, hopefully this saved you a few seconds of anguish...