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ip[6]_tryforward does inbound and outbound packet firewall processing.

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This can lead to change of mbuf pointer (packet filter could do m_pullup(),
NAT, etc). Also in case of change of destination address, tryforward can
decide that packet should be handled by local system. In this case modified
mbuf can be returned to the ip[6]_input(). To handle this correctly, check
M_FASTFWD_OURS flag after return from ip[6]_tryforward. And if it is present,
update variables that depend from mbuf pointer and skip another inbound
firewall processing.

No objection from:	#network
MFC after:	3 weeks
Sponsored by:	Yandex LLC
Differential Revision:	https://reviews.freebsd.org/D8764
This commit is contained in:
Andrey V. Elsukov 2016-12-19 11:02:49 +00:00
parent d9ba4eefdc
commit ad9f4d6ab6
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=310258
2 changed files with 46 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

33
sys/netinet/ip_input.c
View File

@ -550,24 +550,35 @@ ip_input(struct mbuf *m)
m_adj(m, ip_len - m->m_pkthdr.len);
}
/* Try to forward the packet, but if we fail continue */
/*
* Try to forward the packet, but if we fail continue.
* ip_tryforward() does inbound and outbound packet firewall
* processing. If firewall has decided that destination becomes
* our local address, it sets M_FASTFWD_OURS flag. In this
* case skip another inbound firewall processing and update
* ip pointer.
*/
if (V_ipforwarding != 0
#ifdef IPSEC
/* For now we do not handle IPSEC in tryforward. */
if (!key_havesp(IPSEC_DIR_INBOUND) && !key_havesp(IPSEC_DIR_OUTBOUND) &&
(V_ipforwarding == 1))
if (ip_tryforward(m) == NULL)
&& !key_havesp(IPSEC_DIR_INBOUND)
&& !key_havesp(IPSEC_DIR_OUTBOUND)
#endif
) {
if ((m = ip_tryforward(m)) == NULL)
return;
if (m->m_flags & M_FASTFWD_OURS) {
m->m_flags &= ~M_FASTFWD_OURS;
ip = mtod(m, struct ip *);
goto ours;
}
}
#ifdef IPSEC
/*
* Bypass packet filtering for packets previously handled by IPsec.
*/
if (ip_ipsec_filtertunnel(m))
goto passin;
#else
if (V_ipforwarding == 1)
if (ip_tryforward(m) == NULL)
return;
#endif /* IPSEC */
#endif
/*
* Run through list of hooks for input packets.
*

35
sys/netinet6/ip6_input.c
View File

@ -726,23 +726,36 @@ ip6_input(struct mbuf *m)
goto bad;
}
#endif
/* Try to forward the packet, but if we fail continue */
/*
* Try to forward the packet, but if we fail continue.
* ip6_tryforward() does inbound and outbound packet firewall
* processing. If firewall has decided that destination becomes
* our local address, it sets M_FASTFWD_OURS flag. In this
* case skip another inbound firewall processing and update
* ip6 pointer.
*/
if (V_ip6_forwarding != 0
#ifdef IPSEC
if (V_ip6_forwarding != 0 && !key_havesp(IPSEC_DIR_INBOUND) &&
!key_havesp(IPSEC_DIR_OUTBOUND))
if (ip6_tryforward(m) == NULL)
&& !key_havesp(IPSEC_DIR_INBOUND)
&& !key_havesp(IPSEC_DIR_OUTBOUND)
#endif
) {
if ((m = ip6_tryforward(m)) == NULL)
return;
if (m->m_flags & M_FASTFWD_OURS) {
m->m_flags &= ~M_FASTFWD_OURS;
ours = 1;
ip6 = mtod(m, struct ip6_hdr *);
goto hbhcheck;
}
}
#ifdef IPSEC
/*
* Bypass packet filtering for packets previously handled by IPsec.
*/
if (ip6_ipsec_filtertunnel(m))
goto passin;
#else
if (V_ip6_forwarding != 0)
if (ip6_tryforward(m) == NULL)
return;
#endif /* IPSEC */
#endif
/*
* Run through list of hooks for input packets.
*
@ -750,12 +763,12 @@ ip6_input(struct mbuf *m)
* (e.g. by NAT rewriting). When this happens,
* tell ip6_forward to do the right thing.
*/
odst = ip6->ip6_dst;
/* Jump over all PFIL processing if hooks are not active. */
if (!PFIL_HOOKED(&V_inet6_pfil_hook))
goto passin;
odst = ip6->ip6_dst;
if (pfil_run_hooks(&V_inet6_pfil_hook, &m,
m->m_pkthdr.rcvif, PFIL_IN, NULL))
return;