Small summary ------------- o Almost all IPsec releated code was moved into sys/netipsec. o New kernel modules added: ipsec.ko and tcpmd5.ko. New kernel option IPSEC_SUPPORT added. It enables support for loading and unloading of ipsec.ko and tcpmd5.ko kernel modules. o IPSEC_NAT_T option was removed. Now NAT-T support is enabled by default. The UDP_ENCAP_ESPINUDP_NON_IKE encapsulation type support was removed. Added TCP/UDP checksum handling for inbound packets that were decapsulated by transport mode SAs. setkey(8) modified to show run-time NAT-T configuration of SA. o New network pseudo interface if_ipsec(4) added. For now it is build as part of ipsec.ko module (or with IPSEC kernel). It implements IPsec virtual tunnels to create route-based VPNs. o The network stack now invokes IPsec functions using special methods. The only one header file <netipsec/ipsec_support.h> should be included to declare all the needed things to work with IPsec. o All IPsec protocols handlers (ESP/AH/IPCOMP protosw) were removed. Now these protocols are handled directly via IPsec methods. o TCP_SIGNATURE support was reworked to be more close to RFC. o PF_KEY SADB was reworked: - now all security associations stored in the single SPI namespace, and all SAs MUST have unique SPI. - several hash tables added to speed up lookups in SADB. - SADB now uses rmlock to protect access, and concurrent threads can do SA lookups in the same time. - many PF_KEY message handlers were reworked to reflect changes in SADB. - SADB_UPDATE message was extended to support new PF_KEY headers: SADB_X_EXT_NEW_ADDRESS_SRC and SADB_X_EXT_NEW_ADDRESS_DST. They can be used by IKE daemon to change SA addresses. o ipsecrequest and secpolicy structures were cardinally changed to avoid locking protection for ipsecrequest. Now we support only limited number (4) of bundled SAs, but they are supported for both INET and INET6. o INPCB security policy cache was introduced. Each PCB now caches used security policies to avoid SP lookup for each packet. o For inbound security policies added the mode, when the kernel does check for full history of applied IPsec transforms. o References counting rules for security policies and security associations were changed. The proper SA locking added into xform code. o xform code was also changed. Now it is possible to unregister xforms. tdb_xxx structures were changed and renamed to reflect changes in SADB/SPDB, and changed rules for locking and refcounting. Reviewed by: gnn, wblock Obtained from: Yandex LLC Relnotes: yes Sponsored by: Yandex LLC Differential Revision: https://reviews.freebsd.org/D9352
436 lines
11 KiB
C
436 lines
11 KiB
C
/*-
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* Copyright (c) 2003 Bruce M. Simpson <bms@spc.org>
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* Copyright (c) 2016 Andrey V. Elsukov <ae@FreeBSD.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/* TCP MD5 Signature Option (RFC2385) */
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_inet.h"
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#include "opt_inet6.h"
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#include "opt_ipsec.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/mbuf.h>
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#include <sys/lock.h>
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#include <sys/md5.h>
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#include <sys/rmlock.h>
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#include <sys/socket.h>
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#include <sys/sockopt.h>
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#include <sys/kernel.h>
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#include <sys/module.h>
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#include <sys/protosw.h>
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#include <netinet/in.h>
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#include <netinet/in_pcb.h>
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#include <netinet/in_systm.h>
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#include <netinet/ip.h>
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#include <netinet/ip_var.h>
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#include <netinet/tcp.h>
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#include <netinet/tcp_var.h>
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#include <net/vnet.h>
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#include <netipsec/ipsec.h>
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#include <netipsec/ipsec_support.h>
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#include <netipsec/xform.h>
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#ifdef INET6
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#include <netinet/ip6.h>
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#include <netipsec/ipsec6.h>
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#endif
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#include <netipsec/key.h>
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#include <netipsec/key_debug.h>
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#define TCP_SIGLEN 16 /* length of computed digest in bytes */
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#define TCP_KEYLEN_MIN 1 /* minimum length of TCP-MD5 key */
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#define TCP_KEYLEN_MAX 80 /* maximum length of TCP-MD5 key */
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static inline void
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tcp_fields_to_net(struct tcphdr *th)
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{
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th->th_seq = htonl(th->th_seq);
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th->th_ack = htonl(th->th_ack);
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th->th_win = htons(th->th_win);
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th->th_urp = htons(th->th_urp);
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}
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static int
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tcp_ipsec_pcbctl(struct inpcb *inp, struct sockopt *sopt)
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{
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struct tcpcb *tp;
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int error, optval;
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INP_WLOCK_ASSERT(inp);
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if (sopt->sopt_name != TCP_MD5SIG) {
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INP_WUNLOCK(inp);
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return (ENOPROTOOPT);
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}
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tp = intotcpcb(inp);
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if (sopt->sopt_dir == SOPT_GET) {
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optval = (tp->t_flags & TF_SIGNATURE) ? 1 : 0;
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INP_WUNLOCK(inp);
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/* On success return with released INP_WLOCK */
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return (sooptcopyout(sopt, &optval, sizeof(optval)));
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}
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INP_WUNLOCK(inp);
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error = sooptcopyin(sopt, &optval, sizeof(optval), sizeof(optval));
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if (error != 0)
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return (error);
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/* INP_WLOCK_RECHECK */
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INP_WLOCK(inp);
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if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
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INP_WUNLOCK(inp);
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return (ECONNRESET);
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}
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if (optval > 0)
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tp->t_flags |= TF_SIGNATURE;
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else
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tp->t_flags &= ~TF_SIGNATURE;
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/* On success return with acquired INP_WLOCK */
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return (error);
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}
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/*
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* Callback function invoked by m_apply() to digest TCP segment data
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* contained within an mbuf chain.
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*/
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static int
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tcp_signature_apply(void *fstate, void *data, u_int len)
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{
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MD5Update(fstate, (u_char *)data, len);
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return (0);
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}
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#ifdef INET
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static int
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ip_pseudo_compute(struct mbuf *m, MD5_CTX *ctx)
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{
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struct ippseudo ipp;
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struct ip *ip;
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ip = mtod(m, struct ip *);
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ipp.ippseudo_src.s_addr = ip->ip_src.s_addr;
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ipp.ippseudo_dst.s_addr = ip->ip_dst.s_addr;
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ipp.ippseudo_p = IPPROTO_TCP;
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ipp.ippseudo_pad = 0;
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ipp.ippseudo_len = htons(m->m_pkthdr.len - (ip->ip_hl << 2));
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MD5Update(ctx, (char *)&ipp, sizeof(ipp));
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return (ip->ip_hl << 2);
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}
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#endif
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#ifdef INET6
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static int
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ip6_pseudo_compute(struct mbuf *m, MD5_CTX *ctx)
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{
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struct ip6_pseudo {
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struct in6_addr src, dst;
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uint32_t len;
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uint32_t nxt;
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} ip6p __aligned(4);
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struct ip6_hdr *ip6;
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ip6 = mtod(m, struct ip6_hdr *);
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ip6p.src = ip6->ip6_src;
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ip6p.dst = ip6->ip6_dst;
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ip6p.len = htonl(m->m_pkthdr.len - sizeof(*ip6)); /* XXX: ext headers */
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ip6p.nxt = htonl(IPPROTO_TCP);
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MD5Update(ctx, (char *)&ip6p, sizeof(ip6p));
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return (sizeof(*ip6));
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}
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#endif
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static int
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tcp_signature_compute(struct mbuf *m, struct tcphdr *th,
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struct secasvar *sav, u_char *buf)
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{
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MD5_CTX ctx;
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int len;
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u_short csum;
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MD5Init(&ctx);
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/* Step 1: Update MD5 hash with IP(v6) pseudo-header. */
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switch (sav->sah->saidx.dst.sa.sa_family) {
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#ifdef INET
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case AF_INET:
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len = ip_pseudo_compute(m, &ctx);
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break;
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#endif
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#ifdef INET6
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case AF_INET6:
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len = ip6_pseudo_compute(m, &ctx);
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break;
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#endif
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default:
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return (EAFNOSUPPORT);
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}
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/*
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* Step 2: Update MD5 hash with TCP header, excluding options.
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* The TCP checksum must be set to zero.
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*/
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csum = th->th_sum;
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th->th_sum = 0;
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MD5Update(&ctx, (char *)th, sizeof(struct tcphdr));
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th->th_sum = csum;
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/*
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* Step 3: Update MD5 hash with TCP segment data.
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* Use m_apply() to avoid an early m_pullup().
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*/
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len += (th->th_off << 2);
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if (m->m_pkthdr.len - len > 0)
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m_apply(m, len, m->m_pkthdr.len - len,
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tcp_signature_apply, &ctx);
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/*
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* Step 4: Update MD5 hash with shared secret.
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*/
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MD5Update(&ctx, sav->key_auth->key_data, _KEYLEN(sav->key_auth));
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MD5Final(buf, &ctx);
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key_sa_recordxfer(sav, m);
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return (0);
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}
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static void
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setsockaddrs(const struct mbuf *m, union sockaddr_union *src,
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union sockaddr_union *dst)
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{
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struct ip *ip;
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IPSEC_ASSERT(m->m_len >= sizeof(*ip), ("unexpected mbuf len"));
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ip = mtod(m, struct ip *);
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switch (ip->ip_v) {
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#ifdef INET
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case IPVERSION:
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ipsec4_setsockaddrs(m, src, dst);
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break;
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#endif
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#ifdef INET6
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case (IPV6_VERSION >> 4):
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ipsec6_setsockaddrs(m, src, dst);
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break;
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#endif
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default:
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bzero(src, sizeof(*src));
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bzero(dst, sizeof(*dst));
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}
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}
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/*
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* Compute TCP-MD5 hash of an *INBOUND* TCP segment.
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* Parameters:
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* m pointer to head of mbuf chain
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* th pointer to TCP header
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* buf pointer to storage for computed MD5 digest
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*
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* Return 0 if successful, otherwise return -1.
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*/
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static int
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tcp_ipsec_input(struct mbuf *m, struct tcphdr *th, u_char *buf)
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{
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char tmpdigest[TCP_SIGLEN];
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struct secasindex saidx;
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struct secasvar *sav;
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setsockaddrs(m, &saidx.src, &saidx.dst);
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saidx.proto = IPPROTO_TCP;
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saidx.mode = IPSEC_MODE_TCPMD5;
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saidx.reqid = 0;
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sav = key_allocsa_tcpmd5(&saidx);
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if (sav == NULL) {
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KMOD_TCPSTAT_INC(tcps_sig_err_buildsig);
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return (EACCES);
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}
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/*
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* tcp_input() operates with TCP header fields in host
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* byte order. We expect them in network byte order.
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*/
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tcp_fields_to_net(th);
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tcp_signature_compute(m, th, sav, tmpdigest);
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tcp_fields_to_host(th);
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key_freesav(&sav);
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if (bcmp(buf, tmpdigest, TCP_SIGLEN) != 0) {
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KMOD_TCPSTAT_INC(tcps_sig_rcvbadsig);
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return (EACCES);
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}
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KMOD_TCPSTAT_INC(tcps_sig_rcvgoodsig);
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return (0);
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}
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/*
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* Compute TCP-MD5 hash of an *OUTBOUND* TCP segment.
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* Parameters:
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* m pointer to head of mbuf chain
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* th pointer to TCP header
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* buf pointer to storage for computed MD5 digest
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*
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* Return 0 if successful, otherwise return error code.
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*/
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static int
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tcp_ipsec_output(struct mbuf *m, struct tcphdr *th, u_char *buf)
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{
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struct secasindex saidx;
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struct secasvar *sav;
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setsockaddrs(m, &saidx.src, &saidx.dst);
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saidx.proto = IPPROTO_TCP;
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saidx.mode = IPSEC_MODE_TCPMD5;
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saidx.reqid = 0;
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sav = key_allocsa_tcpmd5(&saidx);
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if (sav == NULL) {
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KMOD_TCPSTAT_INC(tcps_sig_err_buildsig);
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return (EACCES);
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}
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tcp_signature_compute(m, th, sav, buf);
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key_freesav(&sav);
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return (0);
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}
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/*
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* Initialize a TCP-MD5 SA. Called when the SA is being set up.
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*
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* We don't need to set up the tdb prefixed fields, as we don't use the
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* opencrypto code; we just perform a key length check.
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*
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* XXX: Currently we have used single 'magic' SPI and need to still
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* support this.
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*
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* This allows per-host granularity without affecting the userland
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* interface, which is a simple socket option toggle switch,
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* TCP_SIGNATURE_ENABLE.
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*
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* To allow per-service granularity requires that we have a means
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* of mapping port to SPI. The mandated way of doing this is to
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* use SPD entries to specify packet flows which get the TCP-MD5
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* treatment, however the code to do this is currently unstable
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* and unsuitable for production use.
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*
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* Therefore we use this compromise in the meantime.
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*/
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static int
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tcpsignature_init(struct secasvar *sav, struct xformsw *xsp)
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{
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int keylen;
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if (sav->alg_auth != SADB_X_AALG_TCP_MD5) {
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DPRINTF(("%s: unsupported authentication algorithm %u\n",
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__func__, sav->alg_auth));
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return (EINVAL);
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}
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if (sav->key_auth == NULL) {
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DPRINTF(("%s: no authentication key present\n", __func__));
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return (EINVAL);
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}
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keylen = _KEYLEN(sav->key_auth);
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if ((keylen < TCP_KEYLEN_MIN) || (keylen > TCP_KEYLEN_MAX)) {
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DPRINTF(("%s: invalid key length %u\n", __func__, keylen));
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return (EINVAL);
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}
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sav->tdb_xform = xsp;
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return (0);
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}
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/*
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* Called when the SA is deleted.
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*/
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static int
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tcpsignature_zeroize(struct secasvar *sav)
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{
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if (sav->key_auth != NULL)
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bzero(sav->key_auth->key_data, _KEYLEN(sav->key_auth));
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sav->tdb_xform = NULL;
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return (0);
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}
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static struct xformsw tcpsignature_xformsw = {
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.xf_type = XF_TCPSIGNATURE,
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.xf_name = "TCP-MD5",
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.xf_init = tcpsignature_init,
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.xf_zeroize = tcpsignature_zeroize,
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};
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static const struct tcpmd5_methods tcpmd5_methods = {
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.input = tcp_ipsec_input,
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.output = tcp_ipsec_output,
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.pcbctl = tcp_ipsec_pcbctl,
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};
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#ifndef KLD_MODULE
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/* TCP-MD5 support is build in the kernel */
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static const struct tcpmd5_support tcpmd5_ipsec = {
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.enabled = IPSEC_MODULE_ENABLED,
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.methods = &tcpmd5_methods
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};
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const struct tcpmd5_support * const tcp_ipsec_support = &tcpmd5_ipsec;
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#endif /* !KLD_MODULE */
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static int
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tcpmd5_modevent(module_t mod, int type, void *data)
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{
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switch (type) {
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case MOD_LOAD:
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xform_attach(&tcpsignature_xformsw);
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#ifdef KLD_MODULE
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tcpmd5_support_enable(&tcpmd5_methods);
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#endif
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break;
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case MOD_UNLOAD:
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#ifdef KLD_MODULE
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tcpmd5_support_disable();
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#endif
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xform_detach(&tcpsignature_xformsw);
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break;
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default:
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return (EOPNOTSUPP);
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}
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return (0);
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}
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static moduledata_t tcpmd5_mod = {
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"tcpmd5",
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tcpmd5_modevent,
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0
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};
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DECLARE_MODULE(tcpmd5, tcpmd5_mod, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY);
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MODULE_VERSION(tcpmd5, 1);
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#ifdef KLD_MODULE
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MODULE_DEPEND(tcpmd5, ipsec_support, 1, 1, 1);
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#endif
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