Re: [libvirt] [PATCH] Inherit namespace feature

This patch adds feature for lxc containers to inherit namespaces. This is very similar to what lxc-tools or docker provides. Look for "man lxc-start" and you will find that you can pass command args as [ --share-[net|ipc|uts] name|pid ]. Or check out docker networking option in which you can give --net=container:NAME_or_ID as an option for sharing namespace. >From this patch you can add extra libvirt option to share namespace in following way. <lxc:namespace> <lxc:sharenet type='netns' value='red'/> <lxc:shareipc type='pid' value='12345'/> <lxc:shareuts type='name' value='container1'/> </lxc:namespace> --- docs/drvlxc.html.in | 18 +++ docs/schemas/domaincommon.rng | 42 ++++++ src/Makefile.am | 4 +- src/lxc/lxc_conf.c | 2 +- src/lxc/lxc_conf.h | 15 +++ src/lxc/lxc_container.c | 236 +++++++++++++++++++++++++++++++++- src/lxc/lxc_domain.c | 164 ++++++++++++++++++++++- src/lxc/lxc_domain.h | 1 + tests/lxcxml2xmldata/lxc-sharenet.xml | 33 +++++ tests/lxcxml2xmltest.c | 1 + 10 files changed, 507 insertions(+), 9 deletions(-) create mode 100644 tests/lxcxml2xmldata/lxc-sharenet.xml diff --git a/docs/drvlxc.html.in b/docs/drvlxc.html.in index a094bd9..d14d4c7 100644 --- a/docs/drvlxc.html.in +++ b/docs/drvlxc.html.in @@ -590,6 +590,24 @@ Note that allowing capabilities that are normally dropped by default can serious affect the security of the container and the host. </p> +<h2><a name="share">Inherit namespaces</a></h2> + +<p> +Libvirt allows you to inherit the namespace from container/process just like lxc tools +or docker provides to share the network namespace. The following can be used to share +required namespaces. If we want to share only one then the other namespaces can be ignored. +</p> +<pre> +&lt;domain type='lxc' xmlns:lxc='http://libvirt.org/schemas/domain/lxc/1.0'&gt; +... +&lt;lxc:namespace&gt; + &lt;lxc:sharenet type='netns' value='red'/&gt; + &lt;lxc:shareuts type='name' value='container1'/&gt; + &lt;lxc:shareipc type='pid' value='12345'/&gt; +&lt;/lxc:namespace&gt; +&lt;/domain&gt; +</pre>

diff --git a/src/Makefile.am b/src/Makefile.am index be63e26..ef96a5a 100644 --- a/src/Makefile.am +++ b/src/Makefile.am @@ -1319,7 +1319,7 @@ libvirt_driver_lxc_impl_la_CFLAGS = \ -I$(srcdir)/access \ -I$(srcdir)/conf \ $(AM_CFLAGS) -libvirt_driver_lxc_impl_la_LIBADD = $(CAPNG_LIBS) $(LIBNL_LIBS) $(FUSE_LIBS) +libvirt_driver_lxc_impl_la_LIBADD = $(CAPNG_LIBS) $(LIBNL_LIBS) $(LIBXML_LIBS) libvirt-lxc.la $(FUSE_LIBS)

if WITH_BLKID libvirt_driver_lxc_impl_la_CFLAGS += $(BLKID_CFLAGS) libvirt_driver_lxc_impl_la_LIBADD += $(BLKID_LIBS) @@ -2709,6 +2709,8 @@ libvirt_lxc_LDADD = \ libvirt-net-rpc.la \ libvirt_security_manager.la \ libvirt_conf.la \ + libvirt.la \ + libvirt-lxc.la \

libvirt_util.la \ ../gnulib/lib/libgnu.la if WITH_DTRACE_PROBES

diff --git a/src/lxc/lxc_container.c b/src/lxc/lxc_container.c index 11e9514..d8362ab 100644 --- a/src/lxc/lxc_container.c +++ b/src/lxc/lxc_container.c @@ -27,6 +27,7 @@ #include <config.h> #include <fcntl.h> +#include <sched.h> #include <limits.h> #include <stdlib.h> #include <stdio.h> @@ -38,7 +39,6 @@ #include <mntent.h> #include <sys/reboot.h> #include <linux/reboot.h> - /* Yes, we want linux private one, for _syscall2() macro */ #include <linux/unistd.h>

@@ -2321,6 +2321,181 @@ virArch lxcContainerGetAlt32bitArch(virArch arch) return VIR_ARCH_NONE; } +struct ns_info { + const char *proc_name; + int clone_flag;

+}ns_info_local[VIR_DOMAIN_NAMESPACE_LAST] = {

+ [VIR_DOMAIN_NAMESPACE_SHARENET] = {"net", CLONE_NEWNET}, + [VIR_DOMAIN_NAMESPACE_SHAREIPC] = {"ipc", CLONE_NEWIPC}, + [VIR_DOMAIN_NAMESPACE_SHAREUTS] = {"uts", CLONE_NEWUTS} +}; + +static int lxcOpen_ns(lxcDomainDefPtr lxcDef, int ns_fd[VIR_DOMAIN_NAMESPACE_LAST])

+{ + int i, n, rc = 0; + virDomainPtr dom = NULL; + virConnectPtr conn = NULL; + pid_t pid; + int nfdlist; + int *fdlist; + char *path = NULL; + char *eptr; + for (i = 0; i < VIR_DOMAIN_NAMESPACE_LAST; i++) + ns_fd[i] = -1; + + if (STREQ_NULLABLE("netns", lxcDef->ns_type[VIR_DOMAIN_NAMESPACE_SHARENET])) { + if (virAsprintf(&path, "/var/run/netns/%s", lxcDef->ns_val[VIR_DOMAIN_NAMESPACE_SHARENET]) < 0) + return -1;

+ ns_fd[VIR_DOMAIN_NAMESPACE_SHARENET] = open(path, O_RDONLY); + VIR_FREE(path); + if (ns_fd[VIR_DOMAIN_NAMESPACE_SHARENET] < 0) { + virReportSystemError(errno, + _("failed to open netns %s"), lxcDef->ns_val[VIR_DOMAIN_NAMESPACE_SHARENET]); + return -1; + } + } + for (i = 0; i < VIR_DOMAIN_NAMESPACE_LAST; i++) { + /* If not yet intialized by above: netns*/ + if (lxcDef->ns_type[i] && ns_fd[i] == -1) { + pid = strtol(lxcDef->ns_val[i], &eptr, 10); + if (*eptr != '\0' || pid < 1) { + /* check if the domain is running, then set the namespaces + * to that container + */ + const char *ns[] = { "user", "ipc", "uts", "net", "pid", "mnt" }; + conn = virConnectOpen("lxc:///"); + if (!conn) { + virReportError(virGetLastError()->code, + _("unable to get connect to lxc %s"), lxcDef->ns_val[i]); + rc = -1; + goto cleanup; + } + dom = virDomainLookupByName(conn, lxcDef->ns_val[i]); + if (!dom) { + virReportError(virGetLastError()->code, + _("Unable to lookup peer containeri %s"), + lxcDef->ns_val[i]); + rc = -1; + goto cleanup; + } + if ((nfdlist = virDomainLxcOpenNamespace(dom, &fdlist, 0)) < 0) { + virReportError(virGetLastError()->code, + _("Unable to open %s"), lxcDef->ns_val[i]); + rc = -1; + goto cleanup; + }

+ for (n = 0; n < ARRAY_CARDINALITY(ns); n++) { + if (STREQ(ns[n], ns_info_local[i].proc_name)) { + ns_fd[i] = fdlist[n]; + } else { + if (VIR_CLOSE(fdlist[n]) < 0) + VIR_ERROR(_("failed to close fd. ignoring..")); + } + } + if (nfdlist > 0) + VIR_FREE(fdlist); + } else { + if (virAsprintf(&path, "/proc/%d/ns/%s", pid, ns_info_local[i].proc_name) < 0) + return -1; + ns_fd[i] = open(path, O_RDONLY); + VIR_FREE(path); + if (ns_fd[i] < 0) { + virReportSystemError(errno, + _("failed to open ns %s"), lxcDef->ns_val[i]); + return -1; + } + } + } + } + cleanup: + if (dom) + virDomainFree(dom); + if (conn) + virConnectClose(conn); + return rc; +}