xref: /src/sys/netinet/in_offload.c

/*	$NetBSD: in_offload.c,v 1.10 2018/07/11 06:00:34 maxv Exp $	*/

/*
 * Copyright (c)2005, 2006 YAMAMOTO Takashi,
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: in_offload.c,v 1.10 2018/07/11 06:00:34 maxv Exp $");

#include <sys/param.h>
#include <sys/mbuf.h>

#include <net/if.h>

#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
#include <netinet/tcp.h>
#include <netinet/in_offload.h>

/*
 * Handle M_CSUM_TSOv4 in software. Split the TCP payload in chunks of
 * size MSS, and send them.
 */
static int
tcp4_segment(struct ifnet *ifp, struct mbuf *m, const struct sockaddr *sa,
    struct rtentry *rt)
{
	int mss;
	int iphlen, thlen;
	int hlen, len;
	struct ip *ip;
	struct tcphdr *th;
	uint16_t ipid;
	uint32_t tcpseq;
	struct mbuf *hdr = NULL;
	struct mbuf *t;
	int error = 0;

	KASSERT((m->m_flags & M_PKTHDR) != 0);
	KASSERT((m->m_pkthdr.csum_flags & M_CSUM_TSOv4) != 0);

	m->m_pkthdr.csum_flags = 0;

	len = m->m_pkthdr.len;
	KASSERT(len >= sizeof(*ip) + sizeof(*th));

	if (m->m_len < sizeof(*ip)) {
		m = m_pullup(m, sizeof(*ip));
		if (m == NULL) {
			error = ENOMEM;
			goto quit;
		}
	}
	ip = mtod(m, struct ip *);
	iphlen = ip->ip_hl * 4;
	KASSERT(ip->ip_v == IPVERSION);
	KASSERT(iphlen >= sizeof(*ip));
	KASSERT(ip->ip_p == IPPROTO_TCP);
	ipid = ntohs(ip->ip_id);

	hlen = iphlen + sizeof(*th);
	if (m->m_len < hlen) {
		m = m_pullup(m, hlen);
		if (m == NULL) {
			error = ENOMEM;
			goto quit;
		}
	}
	th = (void *)(mtod(m, char *) + iphlen);
	tcpseq = ntohl(th->th_seq);
	thlen = th->th_off * 4;
	hlen = iphlen + thlen;

	mss = m->m_pkthdr.segsz;
	KASSERT(mss != 0);
	KASSERT(len > hlen);

	t = m_split(m, hlen, M_NOWAIT);
	if (t == NULL) {
		error = ENOMEM;
		goto quit;
	}
	hdr = m;
	m = t;
	len -= hlen;
	KASSERT(len % mss == 0);
	while (len > 0) {
		struct mbuf *n;

		n = m_dup(hdr, 0, hlen, M_NOWAIT);
		if (n == NULL) {
			error = ENOMEM;
			goto quit;
		}
		KASSERT(n->m_len == hlen); /* XXX */

		t = m_split(m, mss, M_NOWAIT);
		if (t == NULL) {
			m_freem(n);
			error = ENOMEM;
			goto quit;
		}
		m_cat(n, m);
		m = t;

		KASSERT(n->m_len >= hlen); /* XXX */

		n->m_pkthdr.len = hlen + mss;
		ip = mtod(n, struct ip *);
		KASSERT(ip->ip_v == IPVERSION);
		ip->ip_len = htons(n->m_pkthdr.len);
		ip->ip_id = htons(ipid);
		th = (void *)(mtod(n, char *) + iphlen);
		th->th_seq = htonl(tcpseq);
		ip->ip_sum = 0;
		ip->ip_sum = in_cksum(n, iphlen);
		th->th_sum = 0;
		th->th_sum = in4_cksum(n, IPPROTO_TCP, iphlen, thlen + mss);

		error = ip_if_output(ifp, n, sa, rt);
		if (error) {
			goto quit;
		}

		tcpseq += mss;
		ipid++;
		len -= mss;
	}

quit:
	if (hdr != NULL) {
		m_freem(hdr);
	}
	if (m != NULL) {
		m_freem(m);
	}

	return error;
}

int
ip_tso_output(struct ifnet *ifp, struct mbuf *m, const struct sockaddr *sa,
    struct rtentry *rt)
{
	return tcp4_segment(ifp, m, sa, rt);
}

/*
 * Compute now in software the IP and TCP/UDP checksums. Cancel the
 * hardware offloading.
 */
void
in_undefer_cksum(struct mbuf *m, size_t hdrlen, int csum_flags)
{
	const size_t iphdrlen = M_CSUM_DATA_IPv4_IPHL(m->m_pkthdr.csum_data);
	uint16_t csum;
	uint16_t ip_len;
	uint16_t *csump;

	KASSERT(m->m_flags & M_PKTHDR);
	KASSERT((m->m_pkthdr.csum_flags & csum_flags) == csum_flags);

	if (__predict_true(hdrlen + sizeof(struct ip) <= m->m_len)) {
		struct ip *ip = (struct ip *)(mtod(m, uint8_t *) + hdrlen);

		ip_len = ip->ip_len;
		csump = &ip->ip_sum;
	} else {
		const size_t ip_len_offset =
		    hdrlen + offsetof(struct ip, ip_len);

		m_copydata(m, ip_len_offset, sizeof(ip_len), &ip_len);
		csump = NULL;
	}
	ip_len = ntohs(ip_len);

	if (csum_flags & M_CSUM_IPv4) {
		csum = in4_cksum(m, 0, hdrlen, iphdrlen);
		if (csump != NULL) {
			*csump = csum;
		} else {
			const size_t offset = hdrlen +
			    offsetof(struct ip, ip_sum);

			m_copyback(m, offset, sizeof(uint16_t), &csum);
		}
	}

	if (csum_flags & (M_CSUM_UDPv4|M_CSUM_TCPv4)) {
		size_t l4offset = hdrlen + iphdrlen;

		csum = in4_cksum(m, 0, l4offset, ip_len - l4offset - hdrlen);
		if (csum == 0 && (csum_flags & M_CSUM_UDPv4) != 0)
			csum = 0xffff;

		l4offset += M_CSUM_DATA_IPv4_OFFSET(m->m_pkthdr.csum_data);

		if (__predict_true(l4offset + sizeof(uint16_t) <= m->m_len)) {
			*(uint16_t *)(mtod(m, char *) + l4offset) = csum;
		} else {
			m_copyback(m, l4offset, sizeof(csum), (void *)&csum);
		}
	}

	m->m_pkthdr.csum_flags ^= csum_flags;
}

/*
 * Compute now in software the TCP/UDP checksum. Cancel the hardware
 * offloading.
 */
void
in_undefer_cksum_tcpudp(struct mbuf *m)
{
	struct ip *ip;
	uint16_t csum, offset;

	ip = mtod(m, struct ip *);
	offset = ip->ip_hl << 2;

	csum = in4_cksum(m, 0, offset, ntohs(ip->ip_len) - offset);
	if (csum == 0 && (m->m_pkthdr.csum_flags & M_CSUM_UDPv4) != 0)
		csum = 0xffff;

	offset += M_CSUM_DATA_IPv4_OFFSET(m->m_pkthdr.csum_data);

	if ((offset + sizeof(uint16_t)) <= m->m_len) {
		*(uint16_t *)(mtod(m, char *) + offset) = csum;
	} else {
		m_copyback(m, offset, sizeof(csum), (void *)&csum);
	}
}