Re:WireGuard: next generation in-kernel modern VPN
by derefr on Tuesday June 28, 2016 @02:30PM
(#11996239)
I'm guessing the parent wasn't really considering the kernel/userland distinction in terms of security (for, after all, a daemon running as root in userland isn't all that different from running in the kernel in terms of attack surface; the real security boundary lies between privileged/unprivileged in userland, not between kernel and userland.)
Rather, I expect what the parent wanted to assert was that a novel malformed packet to a badly written VPN shouldn't bring down the entire VPN gateway machine, but rather just the VPN daemon itself, which can then be brought back up by init(8).
Or, to put it another way—even though the Linux kernel is monolithic, it can still pay to treat it as a microkernel and isolate fault-prone code outside of it.
This was one of the original big benefits of running e.g. the NTFS-3G in FUSE, when that support was experimental: the NTFS-3G driver did crash—often!—and your OS stayed up. The—usually external—drive would just get unmounted, and have to be fsck(8)ed.
Now, the argument you used also kind of answers this: in full deployments, we've got dedicated VPN gateways on either side of the connection, so if the VPN process crashes, the whole machine may as well have crashed, since it's not doing much of anything else anyway.
That's probably true for most networks, but I could think of one exception: a VPN gateway serving multiple customer sites. You'd really rather that one VPN "receiver" process crash on that host (like one webserver instance serving one request) than that the whole machine crash.
Rather, I expect what the parent wanted to assert was that a novel malformed packet to a badly written VPN shouldn't bring down the entire VPN gateway machine, but rather just the VPN daemon itself, which can then be brought back up by init(8).
Or, to put it another way—even though the Linux kernel is monolithic, it can still pay to treat it as a microkernel and isolate fault-prone code outside of it.
This was one of the original big benefits of running e.g. the NTFS-3G in FUSE, when that support was experimental: the NTFS-3G driver did crash—often!—and your OS stayed up. The—usually external—drive would just get unmounted, and have to be fsck(8)ed.
Now, the argument you used also kind of answers this: in full deployments, we've got dedicated VPN gateways on either side of the connection, so if the VPN process crashes, the whole machine may as well have crashed, since it's not doing much of anything else anyway.
That's probably true for most networks, but I could think of one exception: a VPN gateway serving multiple customer sites. You'd really rather that one VPN "receiver" process crash on that host (like one webserver instance serving one request) than that the whole machine crash.