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Looney" Date: Fri, 16 Nov 2018 18:32:49 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r340483 - head/sys/netinet X-SVN-Group: head X-SVN-Commit-Author: jtl X-SVN-Commit-Paths: head/sys/netinet X-SVN-Commit-Revision: 340483 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: BF9348A79D X-Spamd-Result: default: False [-106.88 / 40.00]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-1.000,0]; ALLOW_DOMAIN_WHITELIST(-100.00)[FreeBSD.org]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_THREE(0.00)[3]; TO_MATCH_ENVRCPT_ALL(0.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; MIME_GOOD(-0.10)[text/plain]; TO_DN_NONE(0.00)[]; HAS_XAW(0.00)[]; R_SPF_SOFTFAIL(0.00)[~all]; DMARC_NA(0.00)[FreeBSD.org]; RCVD_COUNT_THREE(0.00)[4]; MX_GOOD(-0.01)[cached: mx1.FreeBSD.org]; NEURAL_HAM_SHORT(-1.00)[-0.998,0]; FROM_EQ_ENVFROM(0.00)[]; R_DKIM_NA(0.00)[]; RCVD_TLS_LAST(0.00)[]; ASN(0.00)[asn:11403, ipnet:2610:1c1:1::/48, country:US]; IP_SCORE(-3.77)[ip: (-9.91), ipnet: 2610:1c1:1::/48(-4.93), asn: 11403(-3.91), country: US(-0.10)] X-Rspamd-Server: mx1.freebsd.org X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 16 Nov 2018 18:32:51 -0000 Author: jtl Date: Fri Nov 16 18:32:48 2018 New Revision: 340483 URL: https://svnweb.freebsd.org/changeset/base/340483 Log: Add some additional length checks to the IPv4 fragmentation code. Specifically, block 0-length fragments, even when the MF bit is clear. Also, ensure that every fragment with the MF bit clear ends at the same offset and that no subsequently-received fragments exceed that offset. Reviewed by: glebius, markj MFC after: 3 days Sponsored by: Netflix Differential Revision: https://reviews.freebsd.org/D17922 Modified: head/sys/netinet/ip_reass.c head/sys/netinet/ip_var.h Modified: head/sys/netinet/ip_reass.c ============================================================================== --- head/sys/netinet/ip_reass.c Fri Nov 16 17:07:54 2018 (r340482) +++ head/sys/netinet/ip_reass.c Fri Nov 16 18:32:48 2018 (r340483) @@ -211,19 +211,21 @@ ip_reass(struct mbuf *m) * convert offset of this to bytes. */ ip->ip_len = htons(ntohs(ip->ip_len) - hlen); - if (ip->ip_off & htons(IP_MF)) { - /* - * Make sure that fragments have a data length - * that's a non-zero multiple of 8 bytes. - */ - if (ip->ip_len == htons(0) || (ntohs(ip->ip_len) & 0x7) != 0) { - IPSTAT_INC(ips_toosmall); /* XXX */ - IPSTAT_INC(ips_fragdropped); - m_freem(m); - return (NULL); - } + /* + * Make sure that fragments have a data length + * that's a non-zero multiple of 8 bytes, unless + * this is the last fragment. + */ + if (ip->ip_len == htons(0) || + ((ip->ip_off & htons(IP_MF)) && (ntohs(ip->ip_len) & 0x7) != 0)) { + IPSTAT_INC(ips_toosmall); /* XXX */ + IPSTAT_INC(ips_fragdropped); + m_freem(m); + return (NULL); + } + if (ip->ip_off & htons(IP_MF)) m->m_flags |= M_IP_FRAG; - } else + else m->m_flags &= ~M_IP_FRAG; ip->ip_off = htons(ntohs(ip->ip_off) << 3); @@ -301,9 +303,28 @@ ip_reass(struct mbuf *m) fp->ipq_src = ip->ip_src; fp->ipq_dst = ip->ip_dst; fp->ipq_frags = m; + if (m->m_flags & M_IP_FRAG) + fp->ipq_maxoff = -1; + else + fp->ipq_maxoff = ntohs(ip->ip_off) + ntohs(ip->ip_len); m->m_nextpkt = NULL; goto done; } else { + /* + * If we already saw the last fragment, make sure + * this fragment's offset looks sane. Otherwise, if + * this is the last fragment, record its endpoint. + */ + if (fp->ipq_maxoff > 0) { + i = ntohs(ip->ip_off) + ntohs(ip->ip_len); + if (((m->m_flags & M_IP_FRAG) && i >= fp->ipq_maxoff) || + ((m->m_flags & M_IP_FRAG) == 0 && + i != fp->ipq_maxoff)) { + fp = NULL; + goto dropfrag; + } + } else if ((m->m_flags & M_IP_FRAG) == 0) + fp->ipq_maxoff = ntohs(ip->ip_off) + ntohs(ip->ip_len); fp->ipq_nfrags++; atomic_add_int(&nfrags, 1); #ifdef MAC Modified: head/sys/netinet/ip_var.h ============================================================================== --- head/sys/netinet/ip_var.h Fri Nov 16 17:07:54 2018 (r340482) +++ head/sys/netinet/ip_var.h Fri Nov 16 18:32:48 2018 (r340483) @@ -61,6 +61,7 @@ struct ipq { u_char ipq_ttl; /* time for reass q to live */ u_char ipq_p; /* protocol of this fragment */ u_short ipq_id; /* sequence id for reassembly */ + int ipq_maxoff; /* total length of packet */ struct mbuf *ipq_frags; /* to ip headers of fragments */ struct in_addr ipq_src,ipq_dst; u_char ipq_nfrags; /* # frags in this packet */