Re:Spectre mitigations murder userspace performance
by nyanpasu64 on Saturday June 19, 2021 @08:09PM
(#27565778)
> Ask yourself, would it be fine if every process had a 4KB/s (basically dialup speed) connection to read any desired byte of another process's address space?
> Of course not.
So if it's not OK for processes to read each others' address spaces, does that mean it's not OK to attach gdb to a running process to figure out where it's stuck at, without running gdb as root? I chose to reenable ptrace among sibling processes on my system out of convenience, and hopefully it's not too much of a vulnerability. (I also chose to enable passwordless sudo, which is convenient, but probably dangerous as well. I wonder if I can use my hardware security key for sudo instead.)
> Of course not.
So if it's not OK for processes to read each others' address spaces, does that mean it's not OK to attach gdb to a running process to figure out where it's stuck at, without running gdb as root? I chose to reenable ptrace among sibling processes on my system out of convenience, and hopefully it's not too much of a vulnerability. (I also chose to enable passwordless sudo, which is convenient, but probably dangerous as well. I wonder if I can use my hardware security key for sudo instead.)