On Tue, Aug 20, 2024 at 03:11:07PM +0200, Günther Noack wrote: > Hello! > > Thanks for sending v2 of this patchset! > > On Wed, Aug 14, 2024 at 11:01:42AM +0800, Mikhail Ivanov wrote: > > Hello! This is v2 RFC patch dedicated to restriction of listening sockets. > > > > It is based on the landlock's mic-next branch on top of 6.11-rc1 kernel > > version. > > > > Description > > =========== > > LANDLOCK_ACCESS_NET_BIND_TCP is useful to limit the scope of "bindable" > > ports to forbid a malicious sandboxed process to impersonate a legitimate > > server process. However, bind(2) might be used by (TCP) clients to set the > > source port to a (legitimate) value. Controlling the ports that can be > > used for listening would allow (TCP) clients to explicitly bind to ports > > that are forbidden for listening. > > > > Such control is implemented with a new LANDLOCK_ACCESS_NET_LISTEN_TCP > > access right that restricts listening on undesired ports with listen(2). > > > > It's worth noticing that this access right doesn't affect changing > > backlog value using listen(2) on already listening socket. For this case > > test ipv4_tcp.double_listen is provided. > > This is a good catch, btw, that seems like the right thing to do. 👍 > > > I am overall happy with this patch set, but left a few remarks in the tests so > far. There are a few style nits here and there. > > A thing that makes me uneasy is that the tests have a lot of logic in > test_restricted_net_fixture(), where instead of the test logic being > straightforward, there are conditionals to tell apart different scenarios and > expect different results. I wish that the style of these tests was more linear. > This patch set is making it a little bit worse, because the logic in > test_restricted_net_fixture() increases. > > I have also made some restructuring suggestions for the kernel code, in the hope > that they simplify things. If they don't because I overlooked something, we can > skip that though. I missed to mention it -- the documentation in Documentation/userspace-api/landlock.rst needs updating as well. —Günther
