Alexei Starovoitov wrote: > On Sat, Nov 23, 2019 at 12:07:48PM +0100, Jakub Sitnicki wrote: > > SOCKMAP now supports storing references to listening sockets. Nothing keeps > > us from using it as an array of sockets to select from in SK_REUSEPORT > > programs. > > > > Whitelist the map type with the BPF helper for selecting socket. However, > > impose a restriction that the selected socket needs to be a listening TCP > > socket or a bound UDP socket (connected or not). > > > > The only other map type that works with the BPF reuseport helper, > > REUSEPORT_SOCKARRAY, has a corresponding check in its update operation > > handler. > > > > Signed-off-by: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx> > > --- [...] > > diff --git a/net/core/filter.c b/net/core/filter.c > > index 49ded4a7588a..e3fb77353248 100644 > > --- a/net/core/filter.c > > +++ b/net/core/filter.c > > @@ -8723,6 +8723,8 @@ BPF_CALL_4(sk_select_reuseport, struct sk_reuseport_kern *, reuse_kern, > > selected_sk = map->ops->map_lookup_elem(map, key); > > if (!selected_sk) > > return -ENOENT; > > + if (!sock_flag(selected_sk, SOCK_RCU_FREE)) > > + return -EINVAL; > > hmm. I wonder whether this breaks existing users... There is already this check in reuseport_array_update_check() /* * sk must be hashed (i.e. listening in the TCP case or binded * in the UDP case) and * it must also be a SO_REUSEPORT sk (i.e. reuse cannot be NULL). * * Also, sk will be used in bpf helper that is protected by * rcu_read_lock(). */ if (!sock_flag(nsk, SOCK_RCU_FREE) || !sk_hashed(nsk) || !nsk_reuse) return -EINVAL; So I believe it should not cause any problems with existing users. Perhaps we could consolidate the checks a bit or move it into the update paths if we wanted. I assume Jakub was just ensuring we don't get here with SOCK_RCU_FREE set from any of the new paths now. I'll let him answer though. > Martin, > what do you think? More eyes the better. > Could you also take a look at other patches too? > In particular patch 7? > Agreed would be good to give 7/8 a look I'm not too familiar with the selftests there.
