On Mon, 2020-10-05 at 15:21 -0700, Jakub Kicinski wrote: > > > Nice, easy & useful, maybe I'll code it up tomorrow. > > > > OK I thought about it a bit more and looked at the code, and it's not > > actually possible to do easily right now, because we can't actually > > point to the bad attribute from the general lib/nlattr.c code ... > > > > Why? Because we don't know right now, e.g. for nla_validate(), where in > > the message we started validation, i.e. the offset of the "head" inside > > the particular message. > > > > For nlmsg_parse() and friends that's a bit easier, but it needs more > > rejiggering than I'm willing to do tonight ;) > > I thought we'd record the const struct nla_policy *tp for the failing > attr in struct netlink_ext_ack and output based on that.
We could, but it's a bit useless if you know "which" attribute caused the issue, but you don't know where it was in the message? That way you wouldn't know the nesting level etc. I mean, we actually have that problem today - the generic lib/nlattr.c policy violation doesn't tell you where exactly the problem occurred, so it'd be good to fix that regardless. johannes
