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From 9450ad80b814fe0ca823696bff468046340d43c8 Mon Sep 17 00:00:00 2001
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Message-Id: <9450ad80b814fe0ca823696bff468046340d43c8@dist-git>
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From: "Daniel P. Berrange" <berrange@redhat.com>
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Date: Tue, 18 Feb 2014 15:45:43 -0700
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Subject: [PATCH] CVE-2013-6456: Avoid unsafe use of /proc/$PID/root in LXC
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chardev hostdev hotplug
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Rewrite lxcDomainAttachDeviceHostdevMiscLive function
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to use the virProcessRunInMountNamespace helper. This avoids
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risk of a malicious guest replacing /dev with a absolute
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symlink, tricking the driver into changing the host OS
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filesystem.
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Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
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(cherry picked from commit 1cadeafcaa422844a27ef622e2a7041d0235bcb3)
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Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
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---
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src/lxc/lxc_driver.c | 66 ++++++++++++++--------------------------------------
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1 file changed, 18 insertions(+), 48 deletions(-)
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diff --git a/src/lxc/lxc_driver.c b/src/lxc/lxc_driver.c
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index 3920ad9..91e491c 100644
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--- a/src/lxc/lxc_driver.c
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+++ b/src/lxc/lxc_driver.c
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@@ -3567,11 +3567,7 @@ lxcDomainAttachDeviceHostdevMiscLive(virLXCDriverPtr driver,
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virLXCDomainObjPrivatePtr priv = vm->privateData;
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virDomainHostdevDefPtr def = dev->data.hostdev;
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int ret = -1;
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- char *dst = NULL;
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- char *vroot = NULL;
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struct stat sb;
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- bool created = false;
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- mode_t mode = 0;
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if (!def->source.caps.u.misc.chardev) {
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virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
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@@ -3599,51 +3595,29 @@ lxcDomainAttachDeviceHostdevMiscLive(virLXCDriverPtr driver,
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goto cleanup;
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}
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- if (virAsprintf(&vroot, "/proc/%llu/root",
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- (unsigned long long)priv->initpid) < 0)
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- goto cleanup;
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-
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- if (virAsprintf(&dst, "%s/%s",
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- vroot,
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- def->source.caps.u.misc.chardev) < 0)
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+ if (virCgroupAllowDevice(priv->cgroup,
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+ 'c',
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+ major(sb.st_rdev),
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+ minor(sb.st_rdev),
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+ VIR_CGROUP_DEVICE_RWM) < 0)
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goto cleanup;
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if (VIR_REALLOC_N(vm->def->hostdevs, vm->def->nhostdevs+1) < 0)
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goto cleanup;
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- if (lxcContainerSetupHostdevCapsMakePath(dst) < 0) {
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- virReportSystemError(errno,
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- _("Unable to create directory for device %s"),
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- dst);
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- goto cleanup;
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- }
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-
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- mode = 0700 | S_IFCHR;
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-
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- VIR_DEBUG("Creating dev %s (%d,%d)",
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- def->source.caps.u.misc.chardev,
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- major(sb.st_rdev), minor(sb.st_rdev));
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- if (mknod(dst, mode, sb.st_rdev) < 0) {
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- virReportSystemError(errno,
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- _("Unable to create device %s"),
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- dst);
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- goto cleanup;
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- }
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- created = true;
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-
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- if (lxcContainerChown(vm->def, dst) < 0)
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- goto cleanup;
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-
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- if (virSecurityManagerSetHostdevLabel(driver->securityManager,
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- vm->def, def, vroot) < 0)
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- goto cleanup;
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-
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- if (virCgroupAllowDevicePath(priv->cgroup, def->source.caps.u.misc.chardev,
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- VIR_CGROUP_DEVICE_RW |
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- VIR_CGROUP_DEVICE_MKNOD) != 0) {
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- virReportError(VIR_ERR_INTERNAL_ERROR,
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- _("cannot allow device %s for domain %s"),
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- def->source.caps.u.misc.chardev, vm->def->name);
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+ if (lxcDomainAttachDeviceMknod(driver,
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+ 0700 | S_IFBLK,
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+ sb.st_rdev,
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+ vm,
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+ dev,
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+ def->source.caps.u.misc.chardev) < 0) {
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+ if (virCgroupDenyDevice(priv->cgroup,
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+ 'c',
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+ major(sb.st_rdev),
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+ minor(sb.st_rdev),
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+ VIR_CGROUP_DEVICE_RWM) < 0)
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+ VIR_WARN("cannot deny device %s for domain %s",
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+ def->source.caps.u.storage.block, vm->def->name);
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goto cleanup;
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}
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@@ -3653,10 +3627,6 @@ lxcDomainAttachDeviceHostdevMiscLive(virLXCDriverPtr driver,
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cleanup:
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virDomainAuditHostdev(vm, def, "attach", ret == 0);
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- if (dst && created && ret < 0)
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- unlink(dst);
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- VIR_FREE(dst);
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- VIR_FREE(vroot);
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return ret;
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}
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--
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1.9.0
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