This helper fetches dependencies for given device mapper target. At the same time, we need to provide a dummy log function because by default libdevmapper prints out error messages to stderr which we need to suppress. Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; --- src/libvirt_private.syms | 4 + src/util/Makefile.inc.am | 2 + src/util/virdevmapper.c | 200 +++++++++++++++++++++++++++++++++++++++++++++++ src/util/virdevmapper.h | 31 ++++++++ 4 files changed, 237 insertions(+) create mode 100644 src/util/virdevmapper.c create mode 100644 src/util/virdevmapper.h diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms index 03fe3b315f..3b7a19cff1 100644 --- a/src/libvirt_private.syms +++ b/src/libvirt_private.syms @@ -1669,6 +1669,10 @@ virDBusMessageUnref; virDBusSetSharedBus; +# util/virdevmapper.h +virDevMapperGetTargets; + + # util/virdnsmasq.h dnsmasqAddDhcpHost; dnsmasqAddHost; diff --git a/src/util/Makefile.inc.am b/src/util/Makefile.inc.am index a3c3b711fd..9624fb687c 100644 --- a/src/util/Makefile.inc.am +++ b/src/util/Makefile.inc.am @@ -35,6 +35,8 @@ UTIL_SOURCES = \ util/virdbus.c \ util/virdbus.h \ util/virdbuspriv.h \ + util/virdevmapper.c \ + util/virdevmapper.h \ util/virdnsmasq.c \ util/virdnsmasq.h \ util/virebtables.c \ diff --git a/src/util/virdevmapper.c b/src/util/virdevmapper.c new file mode 100644 index 0000000000..9491848f48 --- /dev/null +++ b/src/util/virdevmapper.c @@ -0,0 +1,200 @@ +/* + * virdevmapper.c: Functions for handling devmapper + * + * Copyright (C) 2018 Red Hat, Inc. + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * This library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library. If not, see + * <http://www.gnu.org/licenses/>;. + * + * Authors: + * Michal Privoznik <mprivozn(a)redhat.com&gt; + */ + +#include <config.h> + +#ifdef MAJOR_IN_MKDEV +# include <sys/mkdev.h> +#elif MAJOR_IN_SYSMACROS +# include <sys/sysmacros.h> +#endif + +#ifdef WITH_DEVMAPPER +# include <libdevmapper.h> +#endif + +#include "virdevmapper.h" +#include "internal.h" +#include "virthread.h" +#include "viralloc.h" +#include "virstring.h" + +#ifdef WITH_DEVMAPPER +static void +virDevMapperDummyLogger(int level ATTRIBUTE_UNUSED, + const char *file ATTRIBUTE_UNUSED, + int line ATTRIBUTE_UNUSED, + int dm_errno ATTRIBUTE_UNUSED, + const char *fmt ATTRIBUTE_UNUSED, + ...) +{ + return; +} + +static int +virDevMapperOnceInit(void) +{ + /* Ideally, we would not need this. But libdevmapper prints + * error messages to stderr by default. Sad but true. */ + dm_log_with_errno_init(virDevMapperDummyLogger); + return 0; +} + + +VIR_ONCE_GLOBAL_INIT(virDevMapper) + + +static int +virDevMapperGetTargetsImpl(const char *path, + char ***devPaths_ret, + unsigned int ttl) +{ + struct dm_task *dmt = NULL; + struct dm_deps *deps; + struct dm_info info; + char **devPaths = NULL; + char **recursiveDevPaths = NULL; + size_t i; + int ret = -1; + + *devPaths_ret = NULL; + + if (virDevMapperInitialize() < 0) + return ret; + + if (!ttl) { + errno = ELOOP; + return ret; + } + + if (!(dmt = dm_task_create(DM_DEVICE_DEPS))) + return ret; + + if (!dm_task_set_name(dmt, path)) { + if (errno == ENOENT) { + /* It's okay, @path is not managed by devmapper => + * not a devmapper device. */ + ret = 0; + } + goto cleanup; + } + + dm_task_no_open_count(dmt); + + if (!dm_task_run(dmt)) + goto cleanup; + + if (!dm_task_get_info(dmt, &info)) + goto cleanup; + + if (!info.exists) { + ret = 0; + goto cleanup; + } + + if (!(deps = dm_task_get_deps(dmt))) + goto cleanup; + + if (VIR_ALLOC_N_QUIET(devPaths, deps->count + 1) < 0) + goto cleanup; + + for (i = 0; i < deps->count; i++) { + if (virAsprintfQuiet(&devPaths[i], "/dev/block/%u:%u", + major(deps->device[i]), + minor(deps->device[i])) < 0) + goto cleanup; + } + + recursiveDevPaths = NULL; + for (i = 0; i < deps->count; i++) { + char **tmpPaths; + + if (virDevMapperGetTargetsImpl(devPaths[i], &tmpPaths, ttl - 1) < 0) + goto cleanup; + + if (tmpPaths && + virStringListMerge(&recursiveDevPaths, &tmpPaths) < 0) { + virStringListFree(tmpPaths); + goto cleanup; + } + } + + if (virStringListMerge(&devPaths, &recursiveDevPaths) < 0) + goto cleanup; + + VIR_STEAL_PTR(*devPaths_ret, devPaths); + ret = 0; + cleanup: + virStringListFree(recursiveDevPaths); + virStringListFree(devPaths); + dm_task_destroy(dmt); + return ret; +} + + +/** + * virDevMapperGetTargets: + * @path: devmapper target + * @devPaths: returned string list of devices + * + * For given @path figure out its targets, and store them in + * @devPaths array. Note, @devPaths is a string list so it's NULL + * terminated. + * + * If @path is not a devmapper device, @devPaths is set to NULL and + * success is returned. + * + * If @path consists of yet another devmapper targets these are + * consulted recursively. + * + * If we don't have permissions to talk to kernel, -1 is returned + * and errno is set to EBADF. + * + * Returns 0 on success, + * -1 otherwise (with errno set, no libvirt error is + * reported) + */ +int +virDevMapperGetTargets(const char *path, + char ***devPaths) +{ + const unsigned int ttl = 4; + + /* Arbitrary limit on recursion level. A devmapper target can + * consist of devices or yet another targets. If that's the + * case, we have to stop recursion somewhere. My dice chose + * four. */ + + return virDevMapperGetTargetsImpl(path, devPaths, ttl); +} + +#else /* ! WITH_DEVMAPPER */ + +int +virDevMapperGetTargets(const char *path ATTRIBUTE_UNUSED, + char ***devPaths ATTRIBUTE_UNUSED) +{ + errno = ENOSYS; + return -1; +} +#endif /* ! WITH_DEVMAPPER */ diff --git a/src/util/virdevmapper.h b/src/util/virdevmapper.h new file mode 100644 index 0000000000..83ec03bd4e --- /dev/null +++ b/src/util/virdevmapper.h @@ -0,0 +1,31 @@ +/* + * virdevmapper.h: Functions for handling devmapper + * + * Copyright (C) 2018 Red Hat, Inc. + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * This library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library. If not, see + * <http://www.gnu.org/licenses/>;. + * + * Authors: + * Michal Privoznik <mprivozn(a)redhat.com&gt; + */ + +#ifndef __VIR_DEVMAPPER_H__ +# define __VIR_DEVMAPPER_H__ + +int +virDevMapperGetTargets(const char *path, + char ***devPaths); + +#endif /* __VIR_DEVMAPPER_H__ */ -- 2.16.1

https://bugzilla.redhat.com/show_bug.cgi?id=1557769 Problem with device mapper targets is that there can be several other devices 'hidden' behind them. For instance, /dev/dm-1 can consist of /dev/sda, /dev/sdb and /dev/sdc. Therefore, when setting up devices CGroup and namespaces we have to take this into account. Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; --- libvirt.spec.in | 2 ++ src/qemu/qemu_cgroup.c | 69 +++++++++++++++++++++++++++++++++++++++++++------- 2 files changed, 62 insertions(+), 9 deletions(-) diff --git a/libvirt.spec.in b/libvirt.spec.in index b55a947ec9..ebfac10866 100644 --- a/libvirt.spec.in +++ b/libvirt.spec.in @@ -796,6 +796,8 @@ Requires: gzip Requires: bzip2 Requires: lzop Requires: xz +# For mpath devices +Requires: device-mapper %if 0%{?fedora} || 0%{?rhel} > 7 Requires: systemd-container %endif diff --git a/src/qemu/qemu_cgroup.c b/src/qemu/qemu_cgroup.c index b604edb31c..42502e1b03 100644 --- a/src/qemu/qemu_cgroup.c +++ b/src/qemu/qemu_cgroup.c @@ -37,6 +37,7 @@ #include "virtypedparam.h" #include "virnuma.h" #include "virsystemd.h" +#include "virdevmapper.h" #define VIR_FROM_THIS VIR_FROM_QEMU @@ -60,7 +61,10 @@ qemuSetupImagePathCgroup(virDomainObjPtr vm, { qemuDomainObjPrivatePtr priv = vm->privateData; int perms = VIR_CGROUP_DEVICE_READ; - int ret; + char **targetPaths = NULL; + size_t i; + int rv; + int ret = -1; if (!virCgroupHasController(priv->cgroup, VIR_CGROUP_CONTROLLER_DEVICES)) return 0; @@ -71,12 +75,35 @@ qemuSetupImagePathCgroup(virDomainObjPtr vm, VIR_DEBUG("Allow path %s, perms: %s", path, virCgroupGetDevicePermsString(perms)); - ret = virCgroupAllowDevicePath(priv->cgroup, path, perms, true); + rv = virCgroupAllowDevicePath(priv->cgroup, path, perms, true); virDomainAuditCgroupPath(vm, priv->cgroup, "allow", path, virCgroupGetDevicePermsString(perms), - ret); + rv); + if (rv < 0) + goto cleanup; + if (virDevMapperGetTargets(path, &targetPaths) < 0 && + errno != ENOSYS && errno != EBADF) { + virReportSystemError(errno, + _("Unable to get devmapper targets for %s"), + path); + goto cleanup; + } + + for (i = 0; targetPaths && targetPaths[i]; i++) { + rv = virCgroupAllowDevicePath(priv->cgroup, targetPaths[i], perms, false); + + virDomainAuditCgroupPath(vm, priv->cgroup, "allow", targetPaths[i], + virCgroupGetDevicePermsString(perms), + rv); + if (rv < 0) + goto cleanup; + } + + ret = 0; + cleanup: + virStringListFree(targetPaths); return ret; } @@ -109,10 +136,11 @@ qemuTeardownImageCgroup(virDomainObjPtr vm, virStorageSourcePtr src) { qemuDomainObjPrivatePtr priv = vm->privateData; - int perms = VIR_CGROUP_DEVICE_READ | - VIR_CGROUP_DEVICE_WRITE | - VIR_CGROUP_DEVICE_MKNOD; - int ret; + int perms = VIR_CGROUP_DEVICE_RWM; + char **targetPaths = NULL; + size_t i; + int rv; + int ret = -1; if (!virCgroupHasController(priv->cgroup, VIR_CGROUP_CONTROLLER_DEVICES)) @@ -126,11 +154,34 @@ qemuTeardownImageCgroup(virDomainObjPtr vm, VIR_DEBUG("Deny path %s", src->path); - ret = virCgroupDenyDevicePath(priv->cgroup, src->path, perms, true); + rv = virCgroupDenyDevicePath(priv->cgroup, src->path, perms, true); virDomainAuditCgroupPath(vm, priv->cgroup, "deny", src->path, - virCgroupGetDevicePermsString(perms), ret); + virCgroupGetDevicePermsString(perms), rv); + if (rv < 0) + goto cleanup; + if (virDevMapperGetTargets(src->path, &targetPaths) < 0 && + errno != ENOSYS && errno != EBADF) { + virReportSystemError(errno, + _("Unable to get devmapper targets for %s"), + src->path); + goto cleanup; + } + + for (i = 0; targetPaths && targetPaths[i]; i++) { + rv = virCgroupDenyDevicePath(priv->cgroup, targetPaths[i], perms, false); + + virDomainAuditCgroupPath(vm, priv->cgroup, "deny", targetPaths[i], + virCgroupGetDevicePermsString(perms), + rv); + if (rv < 0) + goto cleanup; + } + + ret = 0; + cleanup: + virStringListFree(targetPaths); return ret; } -- 2.16.1

On Tue, Apr 03, 2018 at 11:03:26 +0200, Michal Privoznik wrote: [...] So this returns 1 if 'path' is not a char or block device ... So in that case this is definitely not necessary and should be skipped.

On Tue, Apr 03, 2018 at 11:03:27 +0200, Michal Privoznik wrote: Again, some background for this would be welcome.