This bug was fixed in the package linux - 4.15.0-42.45 --------------- linux (4.15.0-42.45) bionic; urgency=medium
* linux: 4.15.0-42.45 -proposed tracker (LP: #1803592) * [FEAT] Guest-dedicated Crypto Adapters (LP: #1787405) - KVM: s390: reset crypto attributes for all vcpus - KVM: s390: vsie: simulate VCPU SIE entry/exit - KVM: s390: introduce and use KVM_REQ_VSIE_RESTART - KVM: s390: refactor crypto initialization - s390: vfio-ap: base implementation of VFIO AP device driver - s390: vfio-ap: register matrix device with VFIO mdev framework - s390: vfio-ap: sysfs interfaces to configure adapters - s390: vfio-ap: sysfs interfaces to configure domains - s390: vfio-ap: sysfs interfaces to configure control domains - s390: vfio-ap: sysfs interface to view matrix mdev matrix - KVM: s390: interface to clear CRYCB masks - s390: vfio-ap: implement mediated device open callback - s390: vfio-ap: implement VFIO_DEVICE_GET_INFO ioctl - s390: vfio-ap: zeroize the AP queues - s390: vfio-ap: implement VFIO_DEVICE_RESET ioctl - KVM: s390: Clear Crypto Control Block when using vSIE - KVM: s390: vsie: Do the CRYCB validation first - KVM: s390: vsie: Make use of CRYCB FORMAT2 clear - KVM: s390: vsie: Allow CRYCB FORMAT-2 - KVM: s390: vsie: allow CRYCB FORMAT-1 - KVM: s390: vsie: allow CRYCB FORMAT-0 - KVM: s390: vsie: allow guest FORMAT-0 CRYCB on host FORMAT-1 - KVM: s390: vsie: allow guest FORMAT-1 CRYCB on host FORMAT-2 - KVM: s390: vsie: allow guest FORMAT-0 CRYCB on host FORMAT-2 - KVM: s390: device attrs to enable/disable AP interpretation - KVM: s390: CPU model support for AP virtualization - s390: doc: detailed specifications for AP virtualization - KVM: s390: fix locking for crypto setting error path - KVM: s390: Tracing APCB changes - s390: vfio-ap: setup APCB mask using KVM dedicated function - s390/zcrypt: Add ZAPQ inline function. - s390/zcrypt: Review inline assembler constraints. - s390/zcrypt: Integrate ap_asm.h into include/asm/ap.h. - s390/zcrypt: fix ap_instructions_available() returncodes - s390/zcrypt: remove VLA usage from the AP bus - s390/zcrypt: Remove deprecated ioctls. - s390/zcrypt: Remove deprecated zcrypt proc interface. - s390/zcrypt: Support up to 256 crypto adapters. - [Config:] Enable CONFIG_S390_AP_IOMMU and set CONFIG_VFIO_AP to module. * Bypass of mount visibility through userns + mount propagation (LP: #1789161) - mount: Retest MNT_LOCKED in do_umount - mount: Don't allow copying MNT_UNBINDABLE|MNT_LOCKED mounts * CVE-2018-18955: nested user namespaces with more than five extents incorrectly grant privileges over inode (LP: #1801924) // CVE-2018-18955 - userns: also map extents in the reverse map to kernel IDs * kdump fail due to an IRQ storm (LP: #1797990) - SAUCE: x86/PCI: Export find_cap() to be used in early PCI code - SAUCE: x86/quirks: Add parameter to clear MSIs early on boot - SAUCE: x86/quirks: Scan all busses for early PCI quirks -- Thadeu Lima de Souza Cascardo <casca...@canonical.com> Thu, 15 Nov 2018 17:01:46 -0200 ** Changed in: linux (Ubuntu Bionic) Status: Fix Committed => Fix Released -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1789161 Title: Bypass of mount visibility through userns + mount propagation Status in linux package in Ubuntu: Fix Committed Status in linux source package in Trusty: Fix Released Status in linux source package in Xenial: Fix Committed Status in linux source package in Bionic: Fix Released Status in linux source package in Cosmic: Fix Released Status in linux source package in Disco: Fix Committed Bug description: [Impact] Jonathan Calmels from NVIDIA reported that he's able to bypass the mount visibility security check in place in the Linux kernel by using a combination of the unbindable property along with the private mount propagation option to allow a unprivileged user to see a path which was purposefully hidden by the root user. [Test Case] Reproducer: # Hide a path to all users using a tmpfs root@castiana:~# mount -t tmpfs tmpfs /sys/devices/ root@castiana:~# # As an unprivileged user, unshare user namespace and mount namespace stgraber@castiana:~$ unshare -U -m -r # Confirm the path is still not accessible root@castiana:~# ls /sys/devices/ # Make /sys recursively unbindable and private root@castiana:~# mount --make-runbindable /sys root@castiana:~# mount --make-private /sys # Recursively bind-mount the rest of /sys over to /mnnt root@castiana:~# mount --rbind /sys/ /mnt # Access our hidden /sys/device as an unprivileged user root@castiana:~# ls /mnt/devices/ breakpoint cpu cstate_core cstate_pkg i915 intel_pt isa kprobe LNXSYSTM:00 msr pci0000:00 platform pnp0 power software system tracepoint uncore_arb uncore_cbox_0 uncore_cbox_1 uprobe virtual [Regression Potential] Low. The fixes are relatively simple. Regressions would most likely be specific to software utilizing user namespaces + mount propagation which is a small (but often important) portion of the Ubuntu archive. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1789161/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp