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Date:      Sat, 19 Dec 2015 16:34:16 -0800
From:      Cy Schubert <Cy.Schubert@komquats.com>
To:        "George V. Neville-Neil" <gnn@FreeBSD.org>
Cc:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   Re: svn commit: r290383 - in head/sys: net netinet
Message-ID:  <201512200034.tBK0YGFx080939@slippy.cwsent.com>
In-Reply-To: Message from "George V. Neville-Neil" <gnn@FreeBSD.org> of "Thu, 05 Nov 2015 07:26:32 %2B0000." <201511050726.tA57QXlu074213@repo.freebsd.org>

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In message <201511050726.tA57QXlu074213@repo.freebsd.org>, "George V. 
Neville-N
eil" writes:
> Author: gnn
> Date: Thu Nov  5 07:26:32 2015
> New Revision: 290383
> URL: https://svnweb.freebsd.org/changeset/base/290383
> 
> Log:
>   Replace the fastforward path with tryforward which does not require a
>   sysctl and will always be on. The former split between default and
>   fast forwarding is removed by this commit while preserving the ability
>   to use all network stack features.
>   
>   Differential Revision:	https://reviews.freebsd.org/D4042
>   Reviewed by:	ae, melifaro, olivier, rwatson
>   MFC after:	1 month
>   Sponsored by:	Rubicon Communications (Netgate)
> 
> Modified:
>   head/sys/net/if_arcsubr.c
>   head/sys/net/if_ethersubr.c
>   head/sys/net/if_fddisubr.c
>   head/sys/net/if_fwsubr.c
>   head/sys/net/if_iso88025subr.c
>   head/sys/netinet/in_var.h
>   head/sys/netinet/ip_fastfwd.c
>   head/sys/netinet/ip_input.c
> 
> Modified: head/sys/net/if_arcsubr.c
> =============================================================================
> =
> --- head/sys/net/if_arcsubr.c	Thu Nov  5 04:16:03 2015	(r290382)
> +++ head/sys/net/if_arcsubr.c	Thu Nov  5 07:26:32 2015	(r290383)
> @@ -550,15 +550,11 @@ arc_input(struct ifnet *ifp, struct mbuf
>  #ifdef INET
>  	case ARCTYPE_IP:
>  		m_adj(m, ARC_HDRNEWLEN);
> -		if ((m = ip_fastforward(m)) == NULL)
> -			return;
>  		isr = NETISR_IP;
>  		break;
>  
>  	case ARCTYPE_IP_OLD:
>  		m_adj(m, ARC_HDRLEN);
> -		if ((m = ip_fastforward(m)) == NULL)
> -			return;
>  		isr = NETISR_IP;
>  		break;
>  
> 
> Modified: head/sys/net/if_ethersubr.c
> =============================================================================
> =
> --- head/sys/net/if_ethersubr.c	Thu Nov  5 04:16:03 2015	(r29038
> 2)
> +++ head/sys/net/if_ethersubr.c	Thu Nov  5 07:26:32 2015	(r29038
> 3)
> @@ -722,8 +722,6 @@ ether_demux(struct ifnet *ifp, struct mb
>  	switch (ether_type) {
>  #ifdef INET
>  	case ETHERTYPE_IP:
> -		if ((m = ip_fastforward(m)) == NULL)
> -			return;
>  		isr = NETISR_IP;
>  		break;
>  
> 
> Modified: head/sys/net/if_fddisubr.c
> =============================================================================
> =
> --- head/sys/net/if_fddisubr.c	Thu Nov  5 04:16:03 2015	(r29038
> 2)
> +++ head/sys/net/if_fddisubr.c	Thu Nov  5 07:26:32 2015	(r29038
> 3)
> @@ -429,8 +429,6 @@ fddi_input(ifp, m)
>  		switch (type) {
>  #ifdef INET
>  		case ETHERTYPE_IP:
> -			if ((m = ip_fastforward(m)) == NULL)
> -				return;
>  			isr = NETISR_IP;
>  			break;
>  
> 
> Modified: head/sys/net/if_fwsubr.c
> =============================================================================
> =
> --- head/sys/net/if_fwsubr.c	Thu Nov  5 04:16:03 2015	(r290382)
> +++ head/sys/net/if_fwsubr.c	Thu Nov  5 07:26:32 2015	(r290383)
> @@ -605,8 +605,6 @@ firewire_input(struct ifnet *ifp, struct
>  	switch (type) {
>  #ifdef INET
>  	case ETHERTYPE_IP:
> -		if ((m = ip_fastforward(m)) == NULL)
> -			return;
>  		isr = NETISR_IP;
>  		break;
>  
> 
> Modified: head/sys/net/if_iso88025subr.c
> =============================================================================
> =
> --- head/sys/net/if_iso88025subr.c	Thu Nov  5 04:16:03 2015	(r29038
> 2)
> +++ head/sys/net/if_iso88025subr.c	Thu Nov  5 07:26:32 2015	(r29038
> 3)
> @@ -519,8 +519,6 @@ iso88025_input(ifp, m)
>  #ifdef INET
>  		case ETHERTYPE_IP:
>  			th->iso88025_shost[0] &= ~(TR_RII); 
> -			if ((m = ip_fastforward(m)) == NULL)
> -				return;
>  			isr = NETISR_IP;
>  			break;
>  
> 
> Modified: head/sys/netinet/in_var.h
> =============================================================================
> =
> --- head/sys/netinet/in_var.h	Thu Nov  5 04:16:03 2015	(r290382)
> +++ head/sys/netinet/in_var.h	Thu Nov  5 07:26:32 2015	(r290383)
> @@ -380,7 +380,7 @@ int	in_scrubprefix(struct in_ifaddr *, u
>  void	ip_input(struct mbuf *);
>  void	ip_direct_input(struct mbuf *);
>  void	in_ifadown(struct ifaddr *ifa, int);
> -struct	mbuf	*ip_fastforward(struct mbuf *);
> +struct	mbuf	*ip_tryforward(struct mbuf *);
>  void	*in_domifattach(struct ifnet *);
>  void	in_domifdetach(struct ifnet *, void *);
>  
> 
> Modified: head/sys/netinet/ip_fastfwd.c
> =============================================================================
> =
> --- head/sys/netinet/ip_fastfwd.c	Thu Nov  5 04:16:03 2015	(r29038
> 2)
> +++ head/sys/netinet/ip_fastfwd.c	Thu Nov  5 07:26:32 2015	(r29038
> 3)
> @@ -108,12 +108,6 @@ __FBSDID("$FreeBSD$");
>  
>  #include <machine/in_cksum.h>
>  
> -static VNET_DEFINE(int, ipfastforward_active);
> -#define	V_ipfastforward_active		VNET(ipfastforward_active)
> -
> -SYSCTL_INT(_net_inet_ip, OID_AUTO, fastforwarding, CTLFLAG_VNET | CTLFLAG_RW
> ,
> -    &VNET_NAME(ipfastforward_active), 0, "Enable fast IP forwarding");
> -
>  static struct sockaddr_in *
>  ip_findroute(struct route *ro, struct in_addr dest, struct mbuf *m)
>  {
> @@ -158,7 +152,7 @@ ip_findroute(struct route *ro, struct in
>   * to ip_input for full processing.
>   */
>  struct mbuf *
> -ip_fastforward(struct mbuf *m)
> +ip_tryforward(struct mbuf *m)
>  {
>  	struct ip *ip;
>  	struct mbuf *m0 = NULL;
> @@ -166,119 +160,20 @@ ip_fastforward(struct mbuf *m)
>  	struct sockaddr_in *dst = NULL;
>  	struct ifnet *ifp;
>  	struct in_addr odest, dest;
> -	uint16_t sum, ip_len, ip_off;
> +	uint16_t ip_len, ip_off;
>  	int error = 0;
> -	int hlen, mtu;
> +	int mtu;
>  	struct m_tag *fwd_tag = NULL;
>  
>  	/*
>  	 * Are we active and forwarding packets?
>  	 */
> -	if (!V_ipfastforward_active || !V_ipforwarding)
> -		return m;
>  
>  	M_ASSERTVALID(m);
>  	M_ASSERTPKTHDR(m);
>  
>  	bzero(&ro, sizeof(ro));
>  
> -	/*
> -	 * Step 1: check for packet drop conditions (and sanity checks)
> -	 */
> -
> -	/*
> -	 * Is entire packet big enough?
> -	 */
> -	if (m->m_pkthdr.len < sizeof(struct ip)) {
> -		IPSTAT_INC(ips_tooshort);
> -		goto drop;
> -	}
> -
> -	/*
> -	 * Is first mbuf large enough for ip header and is header present?
> -	 */
> -	if (m->m_len < sizeof (struct ip) &&
> -	   (m = m_pullup(m, sizeof (struct ip))) == NULL) {
> -		IPSTAT_INC(ips_toosmall);
> -		return NULL;	/* mbuf already free'd */
> -	}
> -
> -	ip = mtod(m, struct ip *);
> -
> -	/*
> -	 * Is it IPv4?
> -	 */
> -	if (ip->ip_v != IPVERSION) {
> -		IPSTAT_INC(ips_badvers);
> -		goto drop;
> -	}
> -
> -	/*
> -	 * Is IP header length correct and is it in first mbuf?
> -	 */
> -	hlen = ip->ip_hl << 2;
> -	if (hlen < sizeof(struct ip)) {	/* minimum header length */
> -		IPSTAT_INC(ips_badhlen);
> -		goto drop;
> -	}
> -	if (hlen > m->m_len) {
> -		if ((m = m_pullup(m, hlen)) == NULL) {
> -			IPSTAT_INC(ips_badhlen);
> -			return NULL;	/* mbuf already free'd */
> -		}
> -		ip = mtod(m, struct ip *);
> -	}
> -
> -	/*
> -	 * Checksum correct?
> -	 */
> -	if (m->m_pkthdr.csum_flags & CSUM_IP_CHECKED)
> -		sum = !(m->m_pkthdr.csum_flags & CSUM_IP_VALID);
> -	else {
> -		if (hlen == sizeof(struct ip))
> -			sum = in_cksum_hdr(ip);
> -		else
> -			sum = in_cksum(m, hlen);
> -	}
> -	if (sum) {
> -		IPSTAT_INC(ips_badsum);
> -		goto drop;
> -	}
> -
> -	/*
> -	 * Remember that we have checked the IP header and found it valid.
> -	 */
> -	m->m_pkthdr.csum_flags |= (CSUM_IP_CHECKED | CSUM_IP_VALID);
> -
> -	ip_len = ntohs(ip->ip_len);
> -
> -	/*
> -	 * Is IP length longer than packet we have got?
> -	 */
> -	if (m->m_pkthdr.len < ip_len) {
> -		IPSTAT_INC(ips_tooshort);
> -		goto drop;
> -	}
> -
> -	/*
> -	 * Is packet longer than IP header tells us? If yes, truncate packet.
> -	 */
> -	if (m->m_pkthdr.len > ip_len) {
> -		if (m->m_len == m->m_pkthdr.len) {
> -			m->m_len = ip_len;
> -			m->m_pkthdr.len = ip_len;
> -		} else
> -			m_adj(m, ip_len - m->m_pkthdr.len);
> -	}
> -
> -	/*
> -	 * Is packet from or to 127/8?
> -	 */
> -	if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
> -	    (ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) {
> -		IPSTAT_INC(ips_badaddr);
> -		goto drop;
> -	}
>  
>  #ifdef ALTQ
>  	/*
> @@ -289,12 +184,10 @@ ip_fastforward(struct mbuf *m)
>  #endif
>  
>  	/*
> -	 * Step 2: fallback conditions to normal ip_input path processing
> -	 */
> -
> -	/*
>  	 * Only IP packets without options
>  	 */
> +	ip = mtod(m, struct ip *);
> +
>  	if (ip->ip_hl != (sizeof(struct ip) >> 2)) {
>  		if (V_ip_doopts == 1)
>  			return m;
> 
> Modified: head/sys/netinet/ip_input.c
> =============================================================================
> =
> --- head/sys/netinet/ip_input.c	Thu Nov  5 04:16:03 2015	(r29038
> 2)
> +++ head/sys/netinet/ip_input.c	Thu Nov  5 07:26:32 2015	(r29038
> 3)
> @@ -79,6 +79,8 @@ __FBSDID("$FreeBSD$");
>  #include <netinet/ip_carp.h>
>  #ifdef IPSEC
>  #include <netinet/ip_ipsec.h>
> +#include <netipsec/ipsec.h>
> +#include <netipsec/key.h>
>  #endif /* IPSEC */
>  #include <netinet/in_rss.h>
>  
> @@ -500,12 +502,22 @@ tooshort:
>  			m_adj(m, ip_len - m->m_pkthdr.len);
>  	}
>  
> +	/* Try to forward the packet, but if we fail continue */
>  #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)
> +			return;
>  	/*
>  	 * 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 */
>  
>  	/*
> 
> 

Hi George,

Sorry for the lateness of this reply, I finally got some time off for 
Christmas and have time to myself to boot.

This breaks ipfilter's ipnat. I want to let you know before anyone MFCs 
this.


-- 
Cheers,
Cy Schubert <Cy.Schubert@komquats.com> or <Cy.Schubert@cschubert.com>
FreeBSD UNIX:  <cy@FreeBSD.org>   Web:  http://www.FreeBSD.org

	The need of the many outweighs the greed of the few.





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