On Thu, Oct 31, 2013 at 04:36:24PM -0500, Serge Hallyn wrote: > This will properly lock libvirt's usage of iptables with > others (like ufw). > > (See https://bugs.launchpad.net/ubuntu/+source/libvirt/+bug/1245322) > > Signed-off-by: Serge Hallyn <serge.hallyn(a)ubuntu.com&gt; > --- > src/util/viriptables.c | 30 ++++++++++++++++++++++++++---- > 1 file changed, 26 insertions(+), 4 deletions(-) > > diff --git a/src/util/viriptables.c b/src/util/viriptables.c > index 16f571e..30d59b6 100644 > --- a/src/util/viriptables.c > +++ b/src/util/viriptables.c > @@ -50,19 +50,25 @@ > #include "virstring.h" > #include "virutil.h" > > +bool iptables_supports_xlock = false; > + > #if HAVE_FIREWALLD > static char *firewall_cmd_path = NULL; > +#endif > > static int > virIpTablesOnceInit(void) > { > + virCommandPtr cmd; > + int status; > + > +#if HAVE_FIREWALLD > firewall_cmd_path = virFindFileInPath("firewall-cmd"); > if (!firewall_cmd_path) { > VIR_INFO("firewall-cmd not found on system. " > "firewalld support disabled for iptables."); > } else { > - virCommandPtr cmd = virCommandNew(firewall_cmd_path); > - int status; > + virCommandNew(firewall_cmd_path); > > virCommandAddArgList(cmd, "--state", NULL); > if (virCommandRun(cmd, &status) < 0 || status != 0) { > @@ -74,13 +80,26 @@ virIpTablesOnceInit(void) > } > virCommandFree(cmd); > } > + > + if (firewall_cmd_path) > + return 0; > + > +#endif > + > + cmd = virCommandNew(IPTABLES_PATH); > + virCommandAddArgList(cmd, "-w", "-L", "-n", NULL); What version of iptables actually has this '-w' flag ? The ubuntu bug

points to an upstream patch, which does locking unconditionally, no mention of any '-w' flag.

Looking on a per-rule basis is pretty lame locking, since changes to iptables are often comprised of many rule changes :-( > + if (virCommandRun(cmd, &status) < 0 || status != 0) { > + VIR_INFO("xtables locking not supported by your iptables"); > + } else { > + VIR_INFO("using xtables locking for iptables"); > + iptables_supports_xlock = true; > + } > + virCommandFree(cmd); > return 0; > } > > VIR_ONCE_GLOBAL_INIT(virIpTables) > > -#endif > - The call to virIptablesInitialize is protected by #if HAVE_FIREWALLD too, so this code will not run on older distros.

On Fri, Nov 01, 2013 at 09:17:58AM -0500, Serge Hallyn wrote: > Quoting Daniel P. Berrange (berrange(a)redhat.com): > > On Thu, Oct 31, 2013 at 04:36:24PM -0500, Serge Hallyn wrote: > > > This will properly lock libvirt's usage of iptables with > > > others (like ufw). > > > > > > (See https://bugs.launchpad.net/ubuntu/+source/libvirt/+bug/1245322) > > > > > > Signed-off-by: Serge Hallyn <serge.hallyn(a)ubuntu.com&gt; > > > --- > > > src/util/viriptables.c | 30 ++++++++++++++++++++++++++---- > > > 1 file changed, 26 insertions(+), 4 deletions(-) > > > > > > diff --git a/src/util/viriptables.c b/src/util/viriptables.c > > > index 16f571e..30d59b6 100644 > > > --- a/src/util/viriptables.c > > > +++ b/src/util/viriptables.c > > > @@ -50,19 +50,25 @@ > > > #include "virstring.h" > > > #include "virutil.h" > > > > > > +bool iptables_supports_xlock = false; > > > + > > > #if HAVE_FIREWALLD > > > static char *firewall_cmd_path = NULL; > > > +#endif > > > > > > static int > > > virIpTablesOnceInit(void) > > > { > > > + virCommandPtr cmd; > > > + int status; > > > + > > > +#if HAVE_FIREWALLD > > > firewall_cmd_path = virFindFileInPath("firewall-cmd"); > > > if (!firewall_cmd_path) { > > > VIR_INFO("firewall-cmd not found on system. " > > > "firewalld support disabled for iptables."); > > > } else { > > > - virCommandPtr cmd = virCommandNew(firewall_cmd_path); > > > - int status; > > > + virCommandNew(firewall_cmd_path); > > > > > > virCommandAddArgList(cmd, "--state", NULL); > > > if (virCommandRun(cmd, &status) < 0 || status != 0) { > > > @@ -74,13 +80,26 @@ virIpTablesOnceInit(void) > > > } > > > virCommandFree(cmd); > > > } > > > + > > > + if (firewall_cmd_path) > > > + return 0; > > > + > > > +#endif > > > + > > > + cmd = virCommandNew(IPTABLES_PATH); > > > + virCommandAddArgList(cmd, "-w", "-L", "-n", NULL); > > > > What version of iptables actually has this '-w' flag ? The ubuntu bug > > It was introduced in 1.4.20, specifically with > > commit 93587a04d0f2511e108bbc4d87a8b9d28a5c5dd8 > Author: Phil Oester <kernel(a)linuxace.com&gt; > Date: Fri May 31 09:07:04 2013 -0400 > > ip[6]tables: Add locking to prevent concurrent instances > > > points to an upstream patch, which does locking unconditionally, no > > mention of any '-w' flag. > > Well yes it locks unconditionally, but without -w it won't wait. So > if there is another app using iptables at the time, then the call fails > and libvirt fails to create the interface. > > > Looking on a per-rule basis is pretty lame locking, since changes > > to iptables are often comprised of many rule changes :-( > > > > > + if (virCommandRun(cmd, &status) < 0 || status != 0) { > > > + VIR_INFO("xtables locking not supported by your iptables"); > > > + } else { > > > + VIR_INFO("using xtables locking for iptables"); > > > + iptables_supports_xlock = true; > > > + } > > > + virCommandFree(cmd); > > > return 0; > > > } > > > > > > VIR_ONCE_GLOBAL_INIT(virIpTables) > > > > > > -#endif > > > - > > > > The call to virIptablesInitialize is protected by > > #if HAVE_FIREWALLD too, so this code will not run > > on older distros. > > I thought I changed that, but I may not properly understand the > libvirt init code. I moved the VIR_ONCE_GLOBAL_INIT(virIptTables) > out from under that ifdef. That macro just does the declaration of the initializer - this still needs to be actually invoked - which is what the (conditional) calls to virIptablesInitialize() later in the file do.

From 757bb5ad2d2d761e9e703a8905e9a4603e83c142 Mon Sep 17 00:00:00 2001

On 10/31/2013 11:36 PM, Serge Hallyn wrote: > This will properly lock libvirt's usage of iptables with > others (like ufw). > > (See https://bugs.launchpad.net/ubuntu/+source/libvirt/+bug/1245322) > > Signed-off-by: Serge Hallyn <serge.hallyn(a)ubuntu.com&gt; > --- > src/util/viriptables.c | 30 ++++++++++++++++++++++++++---- > 1 file changed, 26 insertions(+), 4 deletions(-) > > diff --git a/src/util/viriptables.c b/src/util/viriptables.c > index 16f571e..30d59b6 100644 > --- a/src/util/viriptables.c > +++ b/src/util/viriptables.c > @@ -50,19 +50,25 @@ > #include "virstring.h" > #include "virutil.h" > > +bool iptables_supports_xlock = false; > + > #if HAVE_FIREWALLD > static char *firewall_cmd_path = NULL; > +#endif > > static int > virIpTablesOnceInit(void) > { > + virCommandPtr cmd; > + int status; > + > +#if HAVE_FIREWALLD > firewall_cmd_path = virFindFileInPath("firewall-cmd"); > if (!firewall_cmd_path) { > VIR_INFO("firewall-cmd not found on system. " > "firewalld support disabled for iptables."); > } else { > - virCommandPtr cmd = virCommandNew(firewall_cmd_path); > - int status; > + virCommandNew(firewall_cmd_path); This needs to be "cmd = virCommandNew(.....);"

Quoting Serge Hallyn (serge.hallyn(a)ubuntu.com): > Quoting Laine Stump (laine(a)laine.org): > > This needs to be "cmd = virCommandNew(.....);" >From 1a43e48dfdc83fbde17d40351465af9031883595 Mon Sep 17 00:00:00 2001 From: Serge Hallyn <serge.hallyn(a)ubuntu.com&gt; Date: Thu, 31 Oct 2013 15:22:16 -0500 Subject: [PATCH 1/1] use -w flag if supported by iptables (v3) Ask iptables to wait rather than fail if it is in use by another caller (like ufw). (See https://bugs.launchpad.net/ubuntu/+source/libvirt/+bug/1245322) Changelog: v2: take virIpTablesInitialize() out of HAVE_FIREWALLD ifdef. v3: make sure to set cmd to the result of virComandNew()

Signed-off-by: Serge Hallyn <serge.hallyn(a)ubuntu.com&gt; --- src/util/viriptables.c | 32 +++++++++++++++++++++++++++----- 1 file changed, 27 insertions(+), 5 deletions(-) diff --git a/src/util/viriptables.c b/src/util/viriptables.c index 16f571e..a1711bb 100644 --- a/src/util/viriptables.c +++ b/src/util/viriptables.c @@ -50,19 +50,25 @@ #include "virstring.h" #include "virutil.h" +bool iptables_supports_xlock = false; + #if HAVE_FIREWALLD static char *firewall_cmd_path = NULL; +#endif static int virIpTablesOnceInit(void) { + virCommandPtr cmd; + int status; + +#if HAVE_FIREWALLD firewall_cmd_path = virFindFileInPath("firewall-cmd"); if (!firewall_cmd_path) { VIR_INFO("firewall-cmd not found on system. " "firewalld support disabled for iptables."); } else { - virCommandPtr cmd = virCommandNew(firewall_cmd_path); - int status; + cmd = virCommandNew(firewall_cmd_path); virCommandAddArgList(cmd, "--state", NULL); if (virCommandRun(cmd, &status) < 0 || status != 0) { @@ -74,13 +80,26 @@ virIpTablesOnceInit(void) } virCommandFree(cmd); } + + if (firewall_cmd_path) + return 0; + +#endif + + cmd = virCommandNew(IPTABLES_PATH); + virCommandAddArgList(cmd, "-w", "-L", "-n", NULL); + if (virCommandRun(cmd, &status) < 0 || status != 0) { + VIR_INFO("xtables locking not supported by your iptables"); + } else { + VIR_INFO("using xtables locking for iptables"); + iptables_supports_xlock = true; + } + virCommandFree(cmd); return 0; } VIR_ONCE_GLOBAL_INIT(virIpTables) -#endif - #define VIR_FROM_THIS VIR_FROM_NONE enum { @@ -92,8 +111,8 @@ static virCommandPtr iptablesCommandNew(const char *table, const char *chain, int family, int action) { virCommandPtr cmd = NULL; -#if HAVE_FIREWALLD virIpTablesInitialize(); +#if HAVE_FIREWALLD if (firewall_cmd_path) { cmd = virCommandNew(firewall_cmd_path); virCommandAddArgList(cmd, "--direct", "--passthrough", @@ -104,6 +123,9 @@ iptablesCommandNew(const char *table, const char *chain, int family, int action) if (cmd == NULL) { cmd = virCommandNew((family == AF_INET6) ? IP6TABLES_PATH : IPTABLES_PATH); + + if (iptables_supports_xlock) + virCommandAddArgList(cmd, "-w", NULL); } virCommandAddArgList(cmd, "--table", table, -- 1.8.3.2 -- libvir-list mailing list libvir-list(a)redhat.com https://www.redhat.com/mailman/listinfo/libvir-list