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pf: Deal with runt packets

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On Ethernet packets have a minimal length, so very short packets get padding
appended to them. This padding is not stripped off in ip6_input() (due to
support for IPv6 Jumbograms, RFC2675).
That means PF needs to be careful when reassembling fragmented packets to not
include the padding in the reassembled packet.

While here also remove the 'Magic from ip_input.' bits. Splitting up and
re-joining an mbuf chain here doesn't make any sense.

Differential Revision:	https://reviews.freebsd.org/D2189
Approved by:		gnn (mentor)
This commit is contained in:
Kristof Provost 2015-04-01 12:16:56 +00:00
parent 798318490e
commit 7dce9b515b
1 changed files with 4 additions and 4 deletions
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8
sys/netpfil/pf/pf_norm.c
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@ -573,11 +573,8 @@ pf_join_fragment(struct pf_fragment *frag)
frent = TAILQ_FIRST(&frag->fr_queue);
next = TAILQ_NEXT(frent, fr_next);
/* Magic from ip_input. */
m = frent->fe_m;
m2 = m->m_next;
m->m_next = NULL;
m_cat(m, m2);
m_adj(m, (frent->fe_hdrlen + frent->fe_len) - m->m_pkthdr.len);
uma_zfree(V_pf_frent_z, frent);
for (frent = next; frent != NULL; frent = next) {
next = TAILQ_NEXT(frent, fr_next);
@ -585,6 +582,9 @@ pf_join_fragment(struct pf_fragment *frag)
m2 = frent->fe_m;
/* Strip off ip header. */
m_adj(m2, frent->fe_hdrlen);
/* Strip off any trailing bytes. */
m_adj(m2, frent->fe_len - m2->m_pkthdr.len);
uma_zfree(V_pf_frent_z, frent);
m_cat(m, m2);
}