Re:Systemd-resolved DNS cache poisoning
by peterwwillis on Wednesday November 12, 2014 @09:58AM
(#8595676)
The short answer is: the glibc DNS interface sucks balls and systemd wanted extra features.
The long answer is:
Often, systems do not come feature-complete. There are many cases of a platform, or OS, or service, or framework, or some other piece of software being released without every possible imaginable feature being implemented. When this happens, some other software may need to re-implement some core piece of technology in order to add functionality to it. Usually care is taken to not interfere with other systems or cause additional burden to the user. In the case of DNS, our use of DNS and different networks simultaneously requires additional functionality in order to process requests independently and efficiently. As the DNS protocol itself has an inherent flaw allowing for cache poisoning, it's non-trivial for people to implement without running into this security hole. And as someone else mentioned, the kernel and glibc don't have their own DNS cache.
I didn't downvote you for the rant because you weren't being mean or insulting and you genuinely seem to want to know what's going on. But next time you feel yourself posting out of emotional reaction, I recommend typing it out in a draft and save it for a half hour, and see if you might want to reword it later to be less angry/ranty.
The long answer is:
Often, systems do not come feature-complete. There are many cases of a platform, or OS, or service, or framework, or some other piece of software being released without every possible imaginable feature being implemented. When this happens, some other software may need to re-implement some core piece of technology in order to add functionality to it. Usually care is taken to not interfere with other systems or cause additional burden to the user. In the case of DNS, our use of DNS and different networks simultaneously requires additional functionality in order to process requests independently and efficiently. As the DNS protocol itself has an inherent flaw allowing for cache poisoning, it's non-trivial for people to implement without running into this security hole. And as someone else mentioned, the kernel and glibc don't have their own DNS cache.
I didn't downvote you for the rant because you weren't being mean or insulting and you genuinely seem to want to know what's going on. But next time you feel yourself posting out of emotional reaction, I recommend typing it out in a draft and save it for a half hour, and see if you might want to reword it later to be less angry/ranty.