pf: Fix parsing of long table names

[kp]

Summary

When parsing the nvlist for a struct pf_addr_wrap we unconditionally
tried to parse "ifname". This broke for PF_ADDR_TABLE when the table
name was longer than IFNAMSIZ. PF_TABLE_NAME_SIZE is longer than
IFNAMSIZ, so this is a valid configuration.

Only parse (or return) ifname or tblname for the corresponding
pf_addr_wrap type.

This manifested as a failure to set rules such as these, where the pfctl
optimiser generated an automatic table:

pass in proto tcp to 192.168.0.1 port ssh
pass in proto tcp to 192.168.0.2 port ssh
pass in proto tcp to 192.168.0.3 port ssh
pass in proto tcp to 192.168.0.4 port ssh
pass in proto tcp to 192.168.0.5 port ssh
pass in proto tcp to 192.168.0.6 port ssh
pass in proto tcp to 192.168.0.7 port ssh

Reported by: Florian Smeets
X-MFC-With: 5c11c5a3655842a176124ef2334fcdf830422c8a
MFC after: 2 weeks
Sponsored by: Rubicon Communications, LLC ("Netgate")

[flo]

The patch works for me. Thanks.

[donner]

lib/libpfctl/libpfctl.c

166–169

Could we have a "switch" here to catch the other (missing) cases?

So those addr->ifname might be unset in contrast to the previous version. Can this cause any harm? What's the default?

[kp]

lib/libpfctl/libpfctl.c

166–169

I think I'd prefer to leave it as is. The fields under addr->v are part of a union, so they used to just always be copied in. We now do a bit more validation, which is what caused the bug this fixes: we checked the length of the ifname string, but that overlapped (because union) with the tblname string, which can be longer.

In fact, it turns out that for type == PF_ADDR_DYNIFTL we still use the mask value, so the resulting conditional would end up being complex (and thus error-prone).