gdb attach fails with ptrace: Operation not permitted

[seifer08ms]

Today I ran into a weird problem. I could not attach to my own process with GDB. The process ran under user docker followed with your instruction, but GDB refused to attach. It complains like that:

Could not attach to process.  If your uid matches the uid of the target
process, check the setting of /proc/sys/kernel/yama/ptrace_scope, or try
again as the root user.  For more details, see /etc/sysctl.d/10-ptrace.conf
ptrace: Operation not permitted.

I googled this issue and tried to modify the 10-ptrace.conf to 0, but GDB continued producing the same error messages. How to solve it ?

[vaibhav276]

@seifer08ms - Whats your setting for /proc/sys/kernel/yama/ptrace_scope?

[seifer08ms]

@vaibhav276
I enter the container with docker exec -it pg_dbg /bin/bash. The content of the file is just '0'.

root@576a3bfc41ff:/# cat /proc/sys/kernel/yama/ptrace_scope
0

[vaibhav276]

Ok, just came across a new flag in docker exec called "--privileged" (https://docs.docker.com/engine/reference/commandline/exec/)

I haven't tried it myself, but you may want to give it a try. Please update if it works, or send in a pull request.

[seifer08ms]

OK,I will try it. Thanks for your help !

[codehimanshu]

If running inside a container, adding --cap-add=SYS_PTRACE during docker run works