On 5/20/22 1:19 AM, Arun Ajith S wrote: > On Thu, Apr 14, 2022 at 3:37 AM David Ahern <dsahern@xxxxxxxxxx> wrote: >> >> On 4/13/22 8:34 AM, Arun Ajith S wrote: >>> diff --git a/tools/testing/selftests/net/ndisc_unsolicited_na_test.py b/tools/testing/selftests/net/ndisc_unsolicited_na_test.py >>> new file mode 100755 >>> index 000000000000..f508657ee126 >>> --- /dev/null >>> +++ b/tools/testing/selftests/net/ndisc_unsolicited_na_test.py >>> @@ -0,0 +1,255 @@ >>> +#!/bin/bash >> >> that file name suffix should be .sh since it is a bash script; not .py >> >> other than that looks good to me. >> >> Reviewed-by: David Ahern <dsahern@xxxxxxxxxx> > > Hi David, > > It has been pointed out to me that I might have read RFC9131 in a > narrower sense than what was intended. > The behavior of adding a new entry in the neighbour cache on receiving > a NA if none exists presently > shouldn't be limited to unsolicited NAs like in my original patch, > rather it should extend to all NAs. > > I am quoting from the RFC below > > | When a valid Neighbor Advertisement is received (either solicited > | or unsolicited), the Neighbor Cache is searched for the target's > | entry. If no entry exists: > | > | * Hosts SHOULD silently discard the advertisement. There is no > | need to create an entry if none exists, since the recipient has > | apparently not initiated any communication with the target. > | > | * Routers SHOULD create a new entry for the target address with > | the link-layer address set to the Target Link-Layer Address > | Option (if supplied). The entry's reachability state MUST be > | set to STALE. If the received Neighbor Advertisement does not > | contain the Target Link-Layer Address Option, the advertisement > | SHOULD be silently discarded. > > I want to fix this, but this would mean the sysctl name > accept_unsolicited_na is no longer appropriate > I see that the net-next window for 5.19 is still open and changing the > sysctl name > wouldn't mean changing an existing interface. > I was thinking of renaming the sysctl to accept_untracked_na to > highlight that we are accepting NAs even if there is > no corresponding entry tracked in the neighbor cache. > > Also, there's an error in my comment, where I say "pass up the stack" > as we don't pass NAs up the stack. > The comment can be updated as: > /* RFC 9131 updates original Neighbour Discovery RFC 4861. > * NAs with Target LL Address option without a corresponding > * entry in the neighbour cache can now create a STALE neighbour > * cache entry on routers. > * > * entry accept fwding solicited behaviour > * ------- ------ ------ --------- ---------------------- > * present X X 0 Set state to STALE > * present X X 1 Set state to REACHABLE > * absent 0 X X Do nothing > * absent 1 0 X Do nothing > * absent 1 1 X Add a new STALE entry > */ > > In summary > 1. accept=0 keeps original(5.18) behavior for all cases. > 2. accept=1 changes original behavior for entry=asbent, fwding=1 case > provided the NA had specified target link-layer address. > > Please let me know what you think. > Changes can be made until it is in a released kernel to users. This feature has many weeks before it hits that level.
