Gabriel Krisman Bertazi <krisman@xxxxxxx> writes: > Jeff Moyer <jmoyer@xxxxxxxxxx> writes: > >> From: Matteo Rizzo <matteorizzo@xxxxxxxxxx> >> >> Introduce a new sysctl (io_uring_disabled) which can be either 0, 1, or >> 2. When 0 (the default), all processes are allowed to create io_uring >> instances, which is the current behavior. When 1, io_uring creation is >> disabled (io_uring_setup() will fail with -EPERM) for processes not in >> the kernel.io_uring_group group. When 2, calls to io_uring_setup() fail >> with -EPERM regardless of privilege. >> >> Signed-off-by: Matteo Rizzo <matteorizzo@xxxxxxxxxx> >> [JEM: modified to add io_uring_group] >> Signed-off-by: Jeff Moyer <jmoyer@xxxxxxxxxx> >> >> --- >> v4: >> >> * Add a kernel.io_uring_group sysctl to hold a group id that is allowed >> to use io_uring. One thing worth pointing out is that, when a group >> is specified, only users in that group can create an io_uring. That >> means that if the root user is not in that group, root can not make >> use of io_uring. > > Rejecting root if it's not in the group doesn't make much sense to > me. Of course, root can always just add itself to the group, so it is > not a security feature. But I'd expect 'sudo <smth>' to not start giving > EPERM based on user group settings. Can you make CAP_SYS_ADMIN > always allowed for option 1? Yes, that's easy to do. I'd like to gather more opinions on this before changing it, though. >> I also wrote unit tests for liburing. I'll post that as well if there >> is consensus on this approach. > > I'm fine with this approach as it allow me to easily reject non-root users. Thanks for taking a look! -Jeff
