pfsync: Do not reference the tag of an imported state

[rcm]

Summary

pfsync_state_import() looks up the tag of a version 1500 state with
pf_tagname2tag(), which takes a reference on the tag and creates it
when no rule uses the name. States do not hold a reference on their
tag, so nothing releases this one: every imported state adds a
reference, and the tag stays allocated after the last rule that uses
it is gone.

Look the tag up without taking a reference, as a state created by a
rule has it. A name that no rule uses is no longer created; nothing
could match it, and the state is imported without a tag.

Fixes: 99475087d63b ("pf: Add pfsync protocol for FreeBSD 15")
MFC after: 1 week
Sponsored by: Rubicon Communications, LLC ("Netgate")

[kp]

sys/netpfil/pf/pf_ioctl.c

843

Should we be implementing this as a call to tagname2tag() with an extra argument to tell it not to take a ref?

[rcm]

Use the existing add_new argument of tagname2tag() instead of a separate lookup: it now also skips the reference and drops the printf. pf_tagname2tag() takes the flag directly, like pf_qname2qid().