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Date:      Fri, 31 Mar 2017 00:41:54 +0000 (UTC)
From:      Steven Hartland <smh@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r316313 - in head: . sys/netinet
Message-ID:  <201703310041.v2V0fsKc058902@repo.freebsd.org>
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Author: smh
Date: Fri Mar 31 00:41:54 2017
New Revision: 316313
URL: https://svnweb.freebsd.org/changeset/base/316313

Log:
  Allow explicitly assigned IPv4 loopback address to be used in jails
  
  If a jail has an explicitly assigned loopback address then allow it to be
  used instead of remapping requests for the loopback adddress to the first
  IPv4 address assigned to the jail.
  
  This fixes issues where applications attempt to detect their bound port
  where they requested a loopback address, which was available, but instead
  the kernel remapped it to the jails first address.
  
  A example of this is binding nginx to 127.0.0.1 and then running "service
  nginx upgrade" which before this change would cause nginx to fail.
  
  Also:
  * Correct the description of prison_check_ip4_locked to match the code.
  
  MFC after:	2 weeks
  Relnotes:	Yes
  Sponsored by:	Multiplay

Modified:
  head/UPDATING
  head/sys/netinet/in_jail.c

Modified: head/UPDATING
==============================================================================
--- head/UPDATING	Fri Mar 31 00:07:03 2017	(r316312)
+++ head/UPDATING	Fri Mar 31 00:41:54 2017	(r316313)
@@ -51,6 +51,11 @@ NOTE TO PEOPLE WHO THINK THAT FreeBSD 12
 
 ****************************** SPECIAL WARNING: ******************************
 
+20170331:
+	Binds and sends to the IPv4 loopback address (127.0.0.1) will now
+	use any explicitly assigned loopback address available in the jail
+	instead of using the first assigned IPv4 address of the jail.
+
 20170329:
 	The ctl.ko module no longer implements the iSCSI target frontend:
 	cfiscsi.ko does instead.

Modified: head/sys/netinet/in_jail.c
==============================================================================
--- head/sys/netinet/in_jail.c	Fri Mar 31 00:07:03 2017	(r316312)
+++ head/sys/netinet/in_jail.c	Fri Mar 31 00:41:54 2017	(r316313)
@@ -306,11 +306,6 @@ prison_local_ip4(struct ucred *cred, str
 	}
 
 	ia0.s_addr = ntohl(ia->s_addr);
-	if (ia0.s_addr == INADDR_LOOPBACK) {
-		ia->s_addr = pr->pr_ip4[0].s_addr;
-		mtx_unlock(&pr->pr_mtx);
-		return (0);
-	}
 
 	if (ia0.s_addr == INADDR_ANY) {
 		/*
@@ -323,6 +318,11 @@ prison_local_ip4(struct ucred *cred, str
 	}
 
 	error = prison_check_ip4_locked(pr, ia);
+	if (error == EADDRNOTAVAIL && ia0.s_addr == INADDR_LOOPBACK) {
+		ia->s_addr = pr->pr_ip4[0].s_addr;
+		error = 0;
+	}
+
 	mtx_unlock(&pr->pr_mtx);
 	return (error);
 }
@@ -354,7 +354,8 @@ prison_remote_ip4(struct ucred *cred, st
 		return (EAFNOSUPPORT);
 	}
 
-	if (ntohl(ia->s_addr) == INADDR_LOOPBACK) {
+	if (ntohl(ia->s_addr) == INADDR_LOOPBACK &&
+	    prison_check_ip4_locked(pr, ia) == EADDRNOTAVAIL) {
 		ia->s_addr = pr->pr_ip4[0].s_addr;
 		mtx_unlock(&pr->pr_mtx);
 		return (0);
@@ -370,9 +371,8 @@ prison_remote_ip4(struct ucred *cred, st
 /*
  * Check if given address belongs to the jail referenced by cred/prison.
  *
- * Returns 0 if jail doesn't restrict IPv4 or if address belongs to jail,
- * EADDRNOTAVAIL if the address doesn't belong, or EAFNOSUPPORT if the jail
- * doesn't allow IPv4.  Address passed in in NBO.
+ * Returns 0 if address belongs to jail,
+ * EADDRNOTAVAIL if the address doesn't belong to the jail.
  */
 int
 prison_check_ip4_locked(const struct prison *pr, const struct in_addr *ia)

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