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Fix IPv6 checksums when exthdrs are present.

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In two places in ip6_output we are doing (delayed) checksum calculations.
The initial logic came from SCTP in r205075,205104 and later I copied
and adjusted it for the TCP|UDP case in r235958.
The problem was that the original SCTP offsets were already wrong for any
case with extension headers present given IPv6 extension headers are not
part of the pseudo checksum calculations.
The later changes do not help in case there is checksum offloading as for
extension headers (incl. fragments) we do currrently never offload as we
have no infrastructure to know whether the NIC can handle these cases.

Correct the offsets for delayed checksum calculations and properly handle
mbuf flags.  In addition harmonize the almost identical duplicate code.

While here eliminate the now unneeded variable hlen and add an always
missing mtod() call in the 1-b and 3 cases after the introduction of
the mb_unmapped_to_ext() calls.

Reported by:	Francis Dupont (fdupont isc.org)
PR:		243675
MFC after:	6 days
Reviewed by:	markj (earlier version), gallatin
Differential Revision:	https://reviews.freebsd.org/D23760
This commit is contained in:
Bjoern A. Zeeb 2020-02-24 19:12:20 +00:00
parent d153d023f5
commit 3459050c9a
1 changed files with 52 additions and 56 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

108
sys/netinet6/ip6_output.c
View File

@ -210,6 +210,44 @@ in6_delayed_cksum(struct mbuf *m, uint32_t plen, u_short offset)
*(u_short *)mtodo(m, offset) = csum;
}
static int
ip6_output_delayed_csum(struct mbuf *m, struct ifnet *ifp, int csum_flags,
int plen, int optlen, bool frag)
{
KASSERT((plen >= optlen), ("%s:%d: plen %d < optlen %d, m %p, ifp %p "
"csum_flags %#x frag %d\n",
__func__, __LINE__, plen, optlen, m, ifp, csum_flags, frag));
if ((csum_flags & CSUM_DELAY_DATA_IPV6) ||
#ifdef SCTP
(csum_flags & CSUM_SCTP_IPV6) ||
#endif
(!frag && (ifp->if_capenable & IFCAP_NOMAP) == 0)) {
m = mb_unmapped_to_ext(m);
if (m == NULL) {
if (frag)
in6_ifstat_inc(ifp, ifs6_out_fragfail);
else
IP6STAT_INC(ip6s_odropped);
return (ENOBUFS);
}
if (csum_flags & CSUM_DELAY_DATA_IPV6) {
in6_delayed_cksum(m, plen - optlen,
sizeof(struct ip6_hdr) + optlen);
m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA_IPV6;
}
#ifdef SCTP
if (csum_flags & CSUM_SCTP_IPV6) {
sctp_delayed_cksum(m, sizeof(struct ip6_hdr) + optlen);
m->m_pkthdr.csum_flags &= ~CSUM_SCTP_IPV6;
}
#endif
}
return (0);
}
int
ip6_fragment(struct ifnet *ifp, struct mbuf *m0, int hlen, u_char nextproto,
int fraglen , uint32_t id)
@ -386,7 +424,7 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
struct ifnet *ifp, *origifp;
struct mbuf *m = m0;
struct mbuf *mprev;
int hlen, tlen, len;
int tlen, len;
struct route_in6 ip6route;
struct rtentry *rt = NULL;
struct sockaddr_in6 *dst, src_sa, dst_sa;
@ -1007,36 +1045,10 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
* XXX-BZ Need a framework to know when the NIC can handle it, even
* with ext. hdrs.
*/
if (sw_csum & CSUM_DELAY_DATA_IPV6) {
sw_csum &= ~CSUM_DELAY_DATA_IPV6;
m = mb_unmapped_to_ext(m);
if (m == NULL) {
error = ENOBUFS;
IP6STAT_INC(ip6s_odropped);
goto bad;
}
in6_delayed_cksum(m, plen, sizeof(struct ip6_hdr));
} else if ((ifp->if_capenable & IFCAP_NOMAP) == 0) {
m = mb_unmapped_to_ext(m);
if (m == NULL) {
error = ENOBUFS;
IP6STAT_INC(ip6s_odropped);
goto bad;
}
}
#ifdef SCTP
if (sw_csum & CSUM_SCTP_IPV6) {
sw_csum &= ~CSUM_SCTP_IPV6;
m = mb_unmapped_to_ext(m);
if (m == NULL) {
error = ENOBUFS;
IP6STAT_INC(ip6s_odropped);
goto bad;
}
sctp_delayed_cksum(m, sizeof(struct ip6_hdr));
}
#endif
m->m_pkthdr.csum_flags &= ifp->if_hwassist;
error = ip6_output_delayed_csum(m, ifp, sw_csum, plen, optlen, false);
if (error != 0)
goto bad;
/* XXX-BZ m->m_pkthdr.csum_flags &= ~ifp->if_hwassist; */
tlen = m->m_pkthdr.len;
if ((opt && (opt->ip6po_flags & IP6PO_DONTFRAG)) || tso)
@ -1099,11 +1111,10 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
* fragment if possible.
* Must be able to put at least 8 bytes per fragment.
*/
hlen = unfragpartlen;
if (mtu > IPV6_MAXPACKET)
mtu = IPV6_MAXPACKET;
len = (mtu - hlen - sizeof(struct ip6_frag)) & ~7;
len = (mtu - unfragpartlen - sizeof(struct ip6_frag)) & ~7;
if (len < 8) {
error = EMSGSIZE;
in6_ifstat_inc(ifp, ifs6_out_fragfail);
@ -1115,28 +1126,11 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
* fragmented packets, then do it here.
* XXX-BZ handle the hw offloading case. Need flags.
*/
if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA_IPV6) {
m = mb_unmapped_to_ext(m);
if (m == NULL) {
in6_ifstat_inc(ifp, ifs6_out_fragfail);
error = ENOBUFS;
goto bad;
}
in6_delayed_cksum(m, plen, hlen);
m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA_IPV6;
}
#ifdef SCTP
if (m->m_pkthdr.csum_flags & CSUM_SCTP_IPV6) {
m = mb_unmapped_to_ext(m);
if (m == NULL) {
in6_ifstat_inc(ifp, ifs6_out_fragfail);
error = ENOBUFS;
goto bad;
}
sctp_delayed_cksum(m, hlen);
m->m_pkthdr.csum_flags &= ~CSUM_SCTP_IPV6;
}
#endif
error = ip6_output_delayed_csum(m, ifp, m->m_pkthdr.csum_flags,
plen, optlen, true);
if (error != 0)
goto bad;
/*
* Change the next header field of the last header in the
* unfragmentable part.
@ -1151,6 +1145,7 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
nextproto = *mtod(exthdrs.ip6e_hbh, u_char *);
*mtod(exthdrs.ip6e_hbh, u_char *) = IPPROTO_FRAGMENT;
} else {
ip6 = mtod(m, struct ip6_hdr *);
nextproto = ip6->ip6_nxt;
ip6->ip6_nxt = IPPROTO_FRAGMENT;
}
@ -1162,7 +1157,8 @@ ip6_output(struct mbuf *m0, struct ip6_pktopts *opt,
*/
m0 = m;
id = htonl(ip6_randomid());
if ((error = ip6_fragment(ifp, m, hlen, nextproto, len, id)))
error = ip6_fragment(ifp, m, unfragpartlen, nextproto,len, id);
if (error != 0)
goto sendorfree;
in6_ifstat_inc(ifp, ifs6_out_fragok);