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Date:      Thu, 24 Oct 2019 20:05:10 +0000 (UTC)
From:      Michael Tuexen <tuexen@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r354044 - in head/sys: netinet netinet6
Message-ID:  <201910242005.x9OK5AFp037383@repo.freebsd.org>

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Author: tuexen
Date: Thu Oct 24 20:05:10 2019
New Revision: 354044
URL: https://svnweb.freebsd.org/changeset/base/354044

Log:
  Ensure that the flags indicating IPv4/IPv6 are not changed by failing
  bind() calls. This would lead to inconsistent state resulting in a panic.
  A fix for stable/11 was committed in
  https://svnweb.freebsd.org/base?view=revision&revision=338986
  An accelerated MFC is planned as discussed with emaste@.
  
  Reported by:		syzbot+2609a378d89264ff5a42@syzkaller.appspotmail.com
  Obtained from:		jtl@
  MFC after:		1 day
  Sponsored by:		Netflix, Inc.

Modified:
  head/sys/netinet/tcp_usrreq.c
  head/sys/netinet6/sctp6_usrreq.c
  head/sys/netinet6/udp6_usrreq.c

Modified: head/sys/netinet/tcp_usrreq.c
==============================================================================
--- head/sys/netinet/tcp_usrreq.c	Thu Oct 24 20:02:48 2019	(r354043)
+++ head/sys/netinet/tcp_usrreq.c	Thu Oct 24 20:05:10 2019	(r354044)
@@ -347,6 +347,7 @@ tcp6_usr_bind(struct socket *so, struct sockaddr *nam,
 	struct inpcb *inp;
 	struct tcpcb *tp = NULL;
 	struct sockaddr_in6 *sin6;
+	u_char vflagsav;
 
 	sin6 = (struct sockaddr_in6 *)nam;
 	if (nam->sa_len != sizeof (*sin6))
@@ -363,6 +364,7 @@ tcp6_usr_bind(struct socket *so, struct sockaddr *nam,
 	inp = sotoinpcb(so);
 	KASSERT(inp != NULL, ("tcp6_usr_bind: inp == NULL"));
 	INP_WLOCK(inp);
+	vflagsav = inp->inp_vflag;
 	if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
 		error = EINVAL;
 		goto out;
@@ -397,6 +399,8 @@ tcp6_usr_bind(struct socket *so, struct sockaddr *nam,
 	error = in6_pcbbind(inp, nam, td->td_ucred);
 	INP_HASH_WUNLOCK(&V_tcbinfo);
 out:
+	if (error != 0)
+		inp->inp_vflag = vflagsav;
 	TCPDEBUG2(PRU_BIND);
 	TCP_PROBE2(debug__user, tp, PRU_BIND);
 	INP_WUNLOCK(inp);
@@ -459,6 +463,7 @@ tcp6_usr_listen(struct socket *so, int backlog, struct
 	int error = 0;
 	struct inpcb *inp;
 	struct tcpcb *tp = NULL;
+	u_char vflagsav;
 
 	TCPDEBUG0;
 	inp = sotoinpcb(so);
@@ -468,6 +473,7 @@ tcp6_usr_listen(struct socket *so, int backlog, struct
 		error = EINVAL;
 		goto out;
 	}
+	vflagsav = inp->inp_vflag;
 	tp = intotcpcb(inp);
 	TCPDEBUG1();
 	SOCK_LOCK(so);
@@ -493,6 +499,9 @@ tcp6_usr_listen(struct socket *so, int backlog, struct
 	if (IS_FASTOPEN(tp->t_flags))
 		tp->t_tfo_pending = tcp_fastopen_alloc_counter();
 
+	if (error != 0)
+		inp->inp_vflag = vflagsav;
+
 out:
 	TCPDEBUG2(PRU_LISTEN);
 	TCP_PROBE2(debug__user, tp, PRU_LISTEN);
@@ -569,6 +578,8 @@ tcp6_usr_connect(struct socket *so, struct sockaddr *n
 	struct inpcb *inp;
 	struct tcpcb *tp = NULL;
 	struct sockaddr_in6 *sin6;
+	u_int8_t incflagsav;
+	u_char vflagsav;
 
 	TCPDEBUG0;
 
@@ -585,6 +596,8 @@ tcp6_usr_connect(struct socket *so, struct sockaddr *n
 	inp = sotoinpcb(so);
 	KASSERT(inp != NULL, ("tcp6_usr_connect: inp == NULL"));
 	INP_WLOCK(inp);
+	vflagsav = inp->inp_vflag;
+	incflagsav = inp->inp_inc.inc_flags;
 	if (inp->inp_flags & INP_TIMEWAIT) {
 		error = EADDRINUSE;
 		goto out;
@@ -618,11 +631,11 @@ tcp6_usr_connect(struct socket *so, struct sockaddr *n
 			error = EAFNOSUPPORT;
 			goto out;
 		}
-		inp->inp_vflag |= INP_IPV4;
-		inp->inp_vflag &= ~INP_IPV6;
 		if ((error = prison_remote_ip4(td->td_ucred,
 		    &sin.sin_addr)) != 0)
 			goto out;
+		inp->inp_vflag |= INP_IPV4;
+		inp->inp_vflag &= ~INP_IPV6;
 		if ((error = tcp_connect(tp, (struct sockaddr *)&sin, td)) != 0)
 			goto out;
 #ifdef TCP_OFFLOAD
@@ -640,11 +653,11 @@ tcp6_usr_connect(struct socket *so, struct sockaddr *n
 		}
 	}
 #endif
+	if ((error = prison_remote_ip6(td->td_ucred, &sin6->sin6_addr)) != 0)
+		goto out;
 	inp->inp_vflag &= ~INP_IPV4;
 	inp->inp_vflag |= INP_IPV6;
 	inp->inp_inc.inc_flags |= INC_ISIPV6;
-	if ((error = prison_remote_ip6(td->td_ucred, &sin6->sin6_addr)) != 0)
-		goto out;
 	if ((error = tcp6_connect(tp, nam, td)) != 0)
 		goto out;
 #ifdef TCP_OFFLOAD
@@ -657,6 +670,15 @@ tcp6_usr_connect(struct socket *so, struct sockaddr *n
 	error = tp->t_fb->tfb_tcp_output(tp);
 
 out:
+	/*
+	 * If the implicit bind in the connect call fails, restore
+	 * the flags we modified.
+	 */
+	if (error != 0 && inp->inp_lport == 0) {
+		inp->inp_vflag = vflagsav;
+		inp->inp_inc.inc_flags = incflagsav;
+	}
+
 	TCPDEBUG2(PRU_CONNECT);
 	TCP_PROBE2(debug__user, tp, PRU_CONNECT);
 	INP_WUNLOCK(inp);
@@ -912,6 +934,9 @@ tcp_usr_send(struct socket *so, int flags, struct mbuf
 #ifdef INET6
 	int isipv6;
 #endif
+	u_int8_t incflagsav;
+	u_char vflagsav;
+	bool restoreflags;
 	TCPDEBUG0;
 
 	/*
@@ -923,6 +948,9 @@ tcp_usr_send(struct socket *so, int flags, struct mbuf
 	inp = sotoinpcb(so);
 	KASSERT(inp != NULL, ("tcp_usr_send: inp == NULL"));
 	INP_WLOCK(inp);
+	vflagsav = inp->inp_vflag;
+	incflagsav = inp->inp_inc.inc_flags;
+	restoreflags = false;
 	if (inp->inp_flags & (INP_TIMEWAIT | INP_DROPPED)) {
 		if (control)
 			m_freem(control);
@@ -1003,6 +1031,7 @@ tcp_usr_send(struct socket *so, int flags, struct mbuf
 						m_freem(m);
 					goto out;
 				}
+				restoreflags = true;
 				inp->inp_vflag &= ~INP_IPV6;
 				sinp = &sin;
 				in6_sin6_2_sin(sinp, sin6);
@@ -1033,6 +1062,7 @@ tcp_usr_send(struct socket *so, int flags, struct mbuf
 					error = EAFNOSUPPORT;
 					goto out;
 				}
+				restoreflags = true;
 				inp->inp_vflag &= ~INP_IPV4;
 				inp->inp_inc.inc_flags |= INC_ISIPV6;
 				if ((error = prison_remote_ip6(td->td_ucred,
@@ -1083,6 +1113,14 @@ tcp_usr_send(struct socket *so, int flags, struct mbuf
 				error = tcp_connect(tp,
 				    (struct sockaddr *)sinp, td);
 #endif
+			/*
+			 * The bind operation in tcp_connect succeeded. We
+			 * no longer want to restore the flags if later
+			 * operations fail.
+			 */
+			if (error == 0 || inp->inp_lport != 0)
+				restoreflags = false;
+
 			if (error)
 				goto out;
 			if (IS_FASTOPEN(tp->t_flags))
@@ -1153,6 +1191,14 @@ tcp_usr_send(struct socket *so, int flags, struct mbuf
 				error = tcp_connect(tp,
 				    (struct sockaddr *)sinp, td);
 #endif
+			/*
+			 * The bind operation in tcp_connect succeeded. We
+			 * no longer want to restore the flags if later
+			 * operations fail.
+			 */
+			if (error == 0 || inp->inp_lport != 0)
+				restoreflags = false;
+
 			if (error)
 				goto out;
 			tp->snd_wnd = TTCP_CLIENT_SND_WND;
@@ -1171,6 +1217,14 @@ tcp_usr_send(struct socket *so, int flags, struct mbuf
 	    TCP_LOG_USERSEND, error,
 	    0, NULL, false);
 out:
+	/*
+	 * If the request was unsuccessful and we changed flags,
+	 * restore the original flags.
+	 */
+	if (error != 0 && restoreflags) {
+		inp->inp_vflag = vflagsav;
+		inp->inp_inc.inc_flags = incflagsav;
+	}
 	TCPDEBUG2((flags & PRUS_OOB) ? PRU_SENDOOB :
 		  ((flags & PRUS_EOF) ? PRU_SEND_EOF : PRU_SEND));
 	TCP_PROBE2(debug__user, tp, (flags & PRUS_OOB) ? PRU_SENDOOB :

Modified: head/sys/netinet6/sctp6_usrreq.c
==============================================================================
--- head/sys/netinet6/sctp6_usrreq.c	Thu Oct 24 20:02:48 2019	(r354043)
+++ head/sys/netinet6/sctp6_usrreq.c	Thu Oct 24 20:05:10 2019	(r354044)
@@ -558,6 +558,7 @@ sctp6_bind(struct socket *so, struct sockaddr *addr, s
 {
 	struct sctp_inpcb *inp;
 	int error;
+	u_char vflagsav;
 
 	inp = (struct sctp_inpcb *)so->so_pcb;
 	if (inp == NULL) {
@@ -588,6 +589,7 @@ sctp6_bind(struct socket *so, struct sockaddr *addr, s
 			return (EINVAL);
 		}
 	}
+	vflagsav = inp->ip_inp.inp.inp_vflag;
 	inp->ip_inp.inp.inp_vflag &= ~INP_IPV4;
 	inp->ip_inp.inp.inp_vflag |= INP_IPV6;
 	if ((addr != NULL) && (SCTP_IPV6_V6ONLY(inp) == 0)) {
@@ -617,7 +619,7 @@ sctp6_bind(struct socket *so, struct sockaddr *addr, s
 					inp->ip_inp.inp.inp_vflag |= INP_IPV4;
 					inp->ip_inp.inp.inp_vflag &= ~INP_IPV6;
 					error = sctp_inpcb_bind(so, (struct sockaddr *)&sin, NULL, p);
-					return (error);
+					goto out;
 				}
 #endif
 				break;
@@ -634,7 +636,8 @@ sctp6_bind(struct socket *so, struct sockaddr *addr, s
 		if (addr->sa_family == AF_INET) {
 			/* can't bind v4 addr to v6 only socket! */
 			SCTP_LTRACE_ERR_RET(inp, NULL, NULL, SCTP_FROM_SCTP6_USRREQ, EINVAL);
-			return (EINVAL);
+			error = EINVAL;
+			goto out;
 		}
 #endif
 		sin6_p = (struct sockaddr_in6 *)addr;
@@ -643,10 +646,14 @@ sctp6_bind(struct socket *so, struct sockaddr *addr, s
 			/* can't bind v4-mapped addrs either! */
 			/* NOTE: we don't support SIIT */
 			SCTP_LTRACE_ERR_RET(inp, NULL, NULL, SCTP_FROM_SCTP6_USRREQ, EINVAL);
-			return (EINVAL);
+			error = EINVAL;
+			goto out;
 		}
 	}
 	error = sctp_inpcb_bind(so, addr, NULL, p);
+out:
+	if (error != 0)
+		inp->ip_inp.inp.inp_vflag = vflagsav;
 	return (error);
 }
 

Modified: head/sys/netinet6/udp6_usrreq.c
==============================================================================
--- head/sys/netinet6/udp6_usrreq.c	Thu Oct 24 20:02:48 2019	(r354043)
+++ head/sys/netinet6/udp6_usrreq.c	Thu Oct 24 20:05:10 2019	(r354044)
@@ -1143,6 +1143,7 @@ udp6_bind(struct socket *so, struct sockaddr *nam, str
 	struct inpcb *inp;
 	struct inpcbinfo *pcbinfo;
 	int error;
+	u_char vflagsav;
 
 	pcbinfo = udp_get_inpcbinfo(so->so_proto->pr_protocol);
 	inp = sotoinpcb(so);
@@ -1150,6 +1151,7 @@ udp6_bind(struct socket *so, struct sockaddr *nam, str
 
 	INP_WLOCK(inp);
 	INP_HASH_WLOCK(pcbinfo);
+	vflagsav = inp->inp_vflag;
 	inp->inp_vflag &= ~INP_IPV4;
 	inp->inp_vflag |= INP_IPV6;
 	if ((inp->inp_flags & IN6P_IPV6_V6ONLY) == 0) {
@@ -1177,6 +1179,8 @@ udp6_bind(struct socket *so, struct sockaddr *nam, str
 #ifdef INET
 out:
 #endif
+	if (error != 0)
+		inp->inp_vflag = vflagsav;
 	INP_HASH_WUNLOCK(pcbinfo);
 	INP_WUNLOCK(inp);
 	return (error);
@@ -1223,6 +1227,7 @@ udp6_connect(struct socket *so, struct sockaddr *nam, 
 	struct inpcbinfo *pcbinfo;
 	struct sockaddr_in6 *sin6;
 	int error;
+	u_char vflagsav;
 
 	pcbinfo = udp_get_inpcbinfo(so->so_proto->pr_protocol);
 	inp = sotoinpcb(so);
@@ -1250,17 +1255,26 @@ udp6_connect(struct socket *so, struct sockaddr *nam, 
 			goto out;
 		}
 		in6_sin6_2_sin(&sin, sin6);
-		inp->inp_vflag |= INP_IPV4;
-		inp->inp_vflag &= ~INP_IPV6;
 		error = prison_remote_ip4(td->td_ucred, &sin.sin_addr);
 		if (error != 0)
 			goto out;
+		vflagsav = inp->inp_vflag;
+		inp->inp_vflag |= INP_IPV4;
+		inp->inp_vflag &= ~INP_IPV6;
 		INP_HASH_WLOCK(pcbinfo);
 		error = in_pcbconnect(inp, (struct sockaddr *)&sin,
 		    td->td_ucred);
 		INP_HASH_WUNLOCK(pcbinfo);
+		/*
+		 * If connect succeeds, mark socket as connected. If
+		 * connect fails and socket is unbound, reset inp_vflag
+		 * field.
+		 */
 		if (error == 0)
 			soisconnected(so);
+		else if (inp->inp_laddr.s_addr == INADDR_ANY &&
+		    inp->inp_lport == 0)
+			inp->inp_vflag = vflagsav;
 		goto out;
 	} else {
 		if ((inp->inp_vflag & INP_IPV6) == 0) {
@@ -1273,16 +1287,25 @@ udp6_connect(struct socket *so, struct sockaddr *nam, 
 		error = EISCONN;
 		goto out;
 	}
-	inp->inp_vflag &= ~INP_IPV4;
-	inp->inp_vflag |= INP_IPV6;
 	error = prison_remote_ip6(td->td_ucred, &sin6->sin6_addr);
 	if (error != 0)
 		goto out;
+	vflagsav = inp->inp_vflag;
+	inp->inp_vflag &= ~INP_IPV4;
+	inp->inp_vflag |= INP_IPV6;
 	INP_HASH_WLOCK(pcbinfo);
 	error = in6_pcbconnect(inp, nam, td->td_ucred);
 	INP_HASH_WUNLOCK(pcbinfo);
+	/*
+	 * If connect succeeds, mark socket as connected. If
+	 * connect fails and socket is unbound, reset inp_vflag
+	 * field.
+	 */
 	if (error == 0)
 		soisconnected(so);
+	else if (IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_laddr) &&
+	    inp->inp_lport == 0)
+		inp->inp_vflag = vflagsav;
 out:
 	INP_WUNLOCK(inp);
 	return (error);



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