From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?q?Timo=20Ter=C3=A4s?= Subject: [PATCH] ipv4: synchronize bind() with RTM_NEWADDR notifications Date: Thu, 21 Oct 2010 13:12:10 +0300 Message-ID: <1287655930-16879-1-git-send-email-timo.teras@iki.fi> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: =?UTF-8?q?Timo=20Ter=C3=A4s?= To: netdev@vger.kernel.org Return-path: Received: from mail-ey0-f174.google.com ([209.85.215.174]:60064 "EHLO mail-ey0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756014Ab0JUKMP (ORCPT ); Thu, 21 Oct 2010 06:12:15 -0400 Received: by eyx24 with SMTP id 24so1876953eyx.19 for ; Thu, 21 Oct 2010 03:12:14 -0700 (PDT) Sender: netdev-owner@vger.kernel.org List-ID: Otherwise we have race condition to user land: 1. process A changes IP address 2. kernel sends RTM_NEWADDR 3. process B gets notification 4. process B tries to bind() to new IP but that fails with EADDRNOTAVAIL because FIB is not yet updated and inet_addr_type() in inet_bind() does not recognize the IP as local 5. kernel calls inetaddr_chain notifiers which updates FIB IPv6 side seems to handle the notifications properly: bind() immediately after RTM_NEWADDR succeeds as expected. This is because ipv6_chk_addr() uses inet6_addr_lst which is updated before address notification. Signed-off-by: Timo Ter=C3=A4s --- net/ipv4/af_inet.c | 9 +++++++++ net/ipv6/af_inet6.c | 4 +++- 2 files changed, 12 insertions(+), 1 deletions(-) diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c index 6a1100c..21200e4 100644 --- a/net/ipv4/af_inet.c +++ b/net/ipv4/af_inet.c @@ -466,6 +466,15 @@ int inet_bind(struct socket *sock, struct sockaddr= *uaddr, int addr_len) if (addr_len < sizeof(struct sockaddr_in)) goto out; =20 + /* Acquire rtnl_lock to synchronize with possible simultaneous + * IP-address changes. This is needed because when RTM_NEWADDR + * is sent the new IP is not yet in FIB, but alas inet_addr_type + * checks the address type using FIB. Acquiring rtnl lock once + * makse sure that any address for which RTM_NEWADDR was sent + * earlier exists also in FIB. */ + rtnl_lock(); + rtnl_unlock(); + chk_addr_ret =3D inet_addr_type(sock_net(sk), addr->sin_addr.s_addr); =20 /* Not specified by any standard per-se, however it breaks too diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c index 56b9bf2..6fc37f4 100644 --- a/net/ipv6/af_inet6.c +++ b/net/ipv6/af_inet6.c @@ -300,7 +300,9 @@ int inet6_bind(struct socket *sock, struct sockaddr= *uaddr, int addr_len) goto out; } =20 - /* Reproduce AF_INET checks to make the bindings consitant */ + /* Reproduce AF_INET checks to make the bindings consistent */ + rtnl_lock(); + rtnl_unlock(); v4addr =3D addr->sin6_addr.s6_addr32[3]; chk_addr_ret =3D inet_addr_type(net, v4addr); if (!sysctl_ip_nonlocal_bind && --=20 1.7.1