On Wed, 19 Jul 2023, Florian Westphal wrote: > Jakub Kicinski <kuba@xxxxxxxxxx> wrote: > > On Tue, 18 Jul 2023 09:52:29 +0200 Florian Westphal wrote: > > > __NLA_IS_BEINT_TYPE(tp) isn't useful. NLA_BE16/32 are identical to > > > NLA_U16/32, the only difference is that it tells the netlink validation > > > functions that byteorder conversion might be needed before comparing > > > the value to the policy min/max ones. > > > > > > After this change all policy macros that can be used with UINT types, > > > such as NLA_POLICY_MASK() can also be used with NLA_BE16/32. > > > > > > This will be used to validate nf_tables flag attributes which > > > are in bigendian byte order. > > > > Semi-related, how well do we do with NLA_F_NET_BYTEORDER? > > Looks incomplete at best. > > > On a quick grep we were using it in the kernel -> user > > direction but not validating on input. Is that right? > > Looks like ipset is the only user, it sets it for kernel->user > dir. > > I see ipset userspace even sets it on user -> kernel dir but > like you say, its not checked and BE encoding is assumed on > kernel side. > > From a quick glance in ipset all Uxx types are always treated as > bigendian, which would mean things should not fall apart if ipset > stops announcing NLA_F_NET_BYTEORDER. Not sure its worth risking > any breakage though. Yes, ipset treats all uxx types as netorder. It checks the presence of the NLA_F_NET_BYTEORDER, see the ip_set_attr_netorder() and ip_set_optattr_netorder() functions in include/linux/netfilter/ipset/ip_set.h which are then used at input validation. The userspace tool also uses and checks the flag in lib/session.c, but it accepts hostorder as well. > I suspect that in practice, given both producer and consumer need > to agree of the meaning of type "12345" anyway its easier to just > agree on the byte ordering as well. > > Was there a specific reason for the question? Best regards, Jozsef - E-mail : kadlec@xxxxxxxxxxxxxxxxx, kadlecsik.jozsef@xxxxxxxxx PGP key : https://wigner.hu/~kadlec/pgp_public_key.txt Address : Wigner Research Centre for Physics H-1525 Budapest 114, POB. 49, Hungary
