Differential D52047
ifpromisc: Ignore "off" requests when refcount is zero Authored by saheed on Aug 20 2025, 1:16 PM. Tags None Referenced Files
Details Adds checks to ensure that the refcount (number of listeners) of Sponsored by: Google LLC (GSoC)
Diff Detail
Event TimelineComment Actions I don't think this is the right solution - there is a bit of an issue with the way we set/unset promiscuity with netlink on FreeBSD. if we are to take the netlink doc to the letter and set ifi_change = 0xFFFFFFFF all the time, then any time we end up calling _nl_modify_ifp_generic we will decrement the promiscuity refcount. This also goes for if we were to use the IFLA_PROMISCUITY attribute (which we don't support yet). on linux my understanding is that the refcounting (which they do with dev->promiscuity) is bypassed when using dev_change_flags instead of dev_set_promiscuity; if we do a no promisc -> promisc transition we increment, and only when we do a promisc -> no promisc transition do we decrement. But in between if we are already promisc and we do a promisc flag set -> promisc flag set transition we don't touch anything (see the (flags ^ dev->gflags) & IFF_PROMISC check). I think we should implement something similar for setting promiscuity through netlink. Or maybe just interpreting IFF_PROMISC as IFF_PPROMISC would be an option. @melifaro @kp do you guys have any input on this? who else can I ping for netlink-related stuff? |