1. 08 Nov, 2018 4 commits
    • Eric W. Biederman's avatar
      mount: Prevent MNT_DETACH from disconnecting locked mounts · 9c8e0a1b
      Eric W. Biederman authored
      Timothy Baldwin <timbaldwin@fastmail.co.uk> wrote:
      > As per mount_namespaces(7) unprivileged users should not be able to look under mount points:
      >   Mounts that come as a single unit from more privileged mount are locked
      >   together and may not be separated in a less privileged mount namespace.
      > However they can:
      > 1. Create a mount namespace.
      > 2. In the mount namespace open a file descriptor to the parent of a mount point.
      > 3. Destroy the mount namespace.
      > 4. Use the file descriptor to look under the mount point.
      > I have reproduced this with Linux 4.16.18 and Linux 4.18-rc8.
      > The setup:
      > $ sudo sysctl kernel.unprivileged_userns_clone=1
      > kernel.unprivileged_userns_clone = 1
      > $ mkdir -p A/B/Secret
      > $ sudo mount -t tmpfs hide A/B
      > "Secret" is indeed hidden as expected:
      > $ ls -lR A
      > A:
      > total 0
      > drwxrwxrwt 2 root root 40 Feb 12 21:08 B
      > A/B:
      > total 0
      > The attack revealing "Secret":
      > $ unshare -Umr sh -c "exec unshare -m ls -lR /proc/self/fd/4/ 4<A"
      > /proc/self/fd/4/:
      > total 0
      > drwxr-xr-x 3 root root 60 Feb 12 21:08 B
      > /proc/self/fd/4/B:
      > total 0
      > drwxr-xr-x 2 root root 40 Feb 12 21:08 Secret
      > /proc/self/fd/4/B/Secret:
      > total 0
      I tracked this down to put_mnt_ns running passing UMOUNT_SYNC and
      disconnecting all of the mounts in a mount namespace.  Fix this by
      factoring drop_mounts out of drop_collected_mounts and passing
      0 instead of UMOUNT_SYNC.
      There are two possible behavior differences that result from this.
      - No longer setting UMOUNT_SYNC will no longer set MNT_SYNC_UMOUNT on
        the vfsmounts being unmounted.  This effects the lazy rcu walk by
        kicking the walk out of rcu mode and forcing it to be a non-lazy
      - No longer disconnecting locked mounts will keep some mounts around
        longer as they stay because the are locked to other mounts.
      There are only two users of drop_collected mounts: audit_tree.c and
      In audit_tree.c the mounts are private and there are no rcu lazy walks
      only calls to iterate_mounts. So the changes should have no effect
      except for a small timing effect as the connected mounts are disconnected.
      In put_mnt_ns there may be references from process outside the mount
      namespace to the mounts.  So the mounts remaining connected will
      be the bug fix that is needed.  That rcu walks are allowed to continue
      appears not to be a problem especially as the rcu walk change was about
      an implementation detail not about semantics.
      Cc: stable@vger.kernel.org
      Fixes: 5ff9d8a6
       ("vfs: Lock in place mounts from more privileged users")
      Reported-by: default avatarTimothy Baldwin <timbaldwin@fastmail.co.uk>
      Tested-by: default avatarTimothy Baldwin <timbaldwin@fastmail.co.uk>
      Signed-off-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
    • Eric W. Biederman's avatar
      mount: Don't allow copying MNT_UNBINDABLE|MNT_LOCKED mounts · df7342b2
      Eric W. Biederman authored
      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.
        # Hide a path to all users using a tmpfs
        root@castiana:~# mount -t tmpfs tmpfs /sys/devices/
        # 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
      Solve this by teaching copy_tree to fail if a mount turns out to be
      both unbindable and locked.
      Cc: stable@vger.kernel.org
      Fixes: 5ff9d8a6
       ("vfs: Lock in place mounts from more privileged users")
      Reported-by: default avatarJonathan Calmels <jcalmels@nvidia.com>
      Signed-off-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
    • Eric W. Biederman's avatar
      mount: Retest MNT_LOCKED in do_umount · 25d202ed
      Eric W. Biederman authored
      It was recently pointed out that the one instance of testing MNT_LOCKED
      outside of the namespace_sem is in ksys_umount.
      Fix that by adding a test inside of do_umount with namespace_sem and
      the mount_lock held.  As it helps to fail fails the existing test is
      maintained with an additional comment pointing out that it may be racy
      because the locks are not held.
      Cc: stable@vger.kernel.org
      Reported-by: default avatarAl Viro <viro@ZenIV.linux.org.uk>
      Fixes: 5ff9d8a6
       ("vfs: Lock in place mounts from more privileged users")
      Signed-off-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
    • Jann Horn's avatar
      userns: also map extents in the reverse map to kernel IDs · d2f007db
      Jann Horn authored
      The current logic first clones the extent array and sorts both copies, then
      maps the lower IDs of the forward mapping into the lower namespace, but
      doesn't map the lower IDs of the reverse mapping.
      This means that code in a nested user namespace with >5 extents will see
      incorrect IDs. It also breaks some access checks, like
      inode_owner_or_capable() and privileged_wrt_inode_uidgid(), so a process
      can incorrectly appear to be capable relative to an inode.
      To fix it, we have to make sure that the "lower_first" members of extents
      in both arrays are translated; and we have to make sure that the reverse
      map is sorted *after* the translation (since otherwise the translation can
      break the sorting).
      This is CVE-2018-18955.
      Fixes: 6397fac4
       ("userns: bump idmap limits to 340")
      Cc: stable@vger.kernel.org
      Signed-off-by: default avatarJann Horn <jannh@google.com>
      Tested-by: default avatarEric W. Biederman <ebiederm@xmission.com>
      Reviewed-by: default avatarEric W. Biederman <ebiederm@xmission.com>
      Signed-off-by: default avatarEric W. Biederman <ebiederm@xmission.com>
  2. 04 Nov, 2018 9 commits
    • Linus Torvalds's avatar
      Linux 4.20-rc1 · 65102238
      Linus Torvalds authored
    • Linus Torvalds's avatar
      Merge tag 'tags/upstream-4.20-rc1' of git://git.infradead.org/linux-ubifs · 42bd06e9
      Linus Torvalds authored
      Pull UBIFS updates from Richard Weinberger:
       - Full filesystem authentication feature, UBIFS is now able to have the
         whole filesystem structure authenticated plus user data encrypted and
       - Minor cleanups
      * tag 'tags/upstream-4.20-rc1' of git://git.infradead.org/linux-ubifs: (26 commits)
        ubifs: Remove unneeded semicolon
        Documentation: ubifs: Add authentication whitepaper
        ubifs: Enable authentication support
        ubifs: Do not update inode size in-place in authenticated mode
        ubifs: Add hashes and HMACs to default filesystem
        ubifs: authentication: Authenticate super block node
        ubifs: Create hash for default LPT
        ubfis: authentication: Authenticate master node
        ubifs: authentication: Authenticate LPT
        ubifs: Authenticate replayed journal
        ubifs: Add auth nodes to garbage collector journal head
        ubifs: Add authentication nodes to journal
        ubifs: authentication: Add hashes to index nodes
        ubifs: Add hashes to the tree node cache
        ubifs: Create functions to embed a HMAC in a node
        ubifs: Add helper functions for authentication support
        ubifs: Add separate functions to init/crc a node
        ubifs: Format changes for authentication support
        ubifs: Store read superblock node
        ubifs: Drop write_node
    • Linus Torvalds's avatar
      Merge tag 'nfs-for-4.20-2' of git://git.linux-nfs.org/projects/trondmy/linux-nfs · 4710e789
      Linus Torvalds authored
      Pull NFS client bugfixes from Trond Myklebust:
       "Highlights include:
         - Fix build issues on architectures that don't provide 64-bit cmpxchg
         - Fix a spelling mistake"
      * tag 'nfs-for-4.20-2' of git://git.linux-nfs.org/projects/trondmy/linux-nfs:
        NFS: fix spelling mistake, EACCESS -> EACCES
        SUNRPC: Use atomic(64)_t for seq_send(64)
    • Linus Torvalds's avatar
      Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · 35e74524
      Linus Torvalds authored
      Pull more timer updates from Thomas Gleixner:
       "A set of commits for the new C-SKY architecture timers"
      * 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        dt-bindings: timer: gx6605s SOC timer
        clocksource/drivers/c-sky: Add gx6605s SOC system timer
        dt-bindings: timer: C-SKY Multi-processor timer
        clocksource/drivers/c-sky: Add C-SKY SMP timer
    • Linus Torvalds's avatar
      Merge tag 'ntb-4.20' of git://github.com/jonmason/ntb · 04578e84
      Linus Torvalds authored
      Pull NTB updates from Jon Mason:
       "Fairly minor changes and bug fixes:
        NTB IDT thermal changes and hook into hwmon, ntb_netdev clean-up of
        private struct, and a few bug fixes"
      * tag 'ntb-4.20' of git://github.com/jonmason/ntb:
        ntb: idt: Alter the driver info comments
        ntb: idt: Discard temperature sensor IRQ handler
        ntb: idt: Add basic hwmon sysfs interface
        ntb: idt: Alter temperature read method
        ntb_netdev: Simplify remove with client device drvdata
        NTB: transport: Try harder to alloc an aligned MW buffer
        ntb: ntb_transport: Mark expected switch fall-throughs
        ntb: idt: Set PCIe bus address to BARLIMITx
        NTB: ntb_hw_idt: replace IS_ERR_OR_NULL with regular NULL checks
        ntb: intel: fix return value for ndev_vec_mask()
        ntb_netdev: fix sleep time mismatch
    • Linus Torvalds's avatar
      Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · 71e56028
      Linus Torvalds authored
      Pull scheduler fixes from Ingo Molnar:
       "A memory (under-)allocation fix and a comment fix"
      * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        sched/topology: Fix off by one bug
        sched/rt: Update comment in pick_next_task_rt()
    • Linus Torvalds's avatar
      Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · 601a8807
      Linus Torvalds authored
      Pull x86 fixes from Ingo Molnar:
       "A number of fixes and some late updates:
         - make in_compat_syscall() behavior on x86-32 similar to other
           platforms, this touches a number of generic files but is not
           intended to impact non-x86 platforms.
         - objtool fixes
         - PAT preemption fix
         - paravirt fixes/cleanups
         - cpufeatures updates for new instructions
         - earlyprintk quirk
         - make microcode version in sysfs world-readable (it is already
           world-readable in procfs)
         - minor cleanups and fixes"
      * 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        compat: Cleanup in_compat_syscall() callers
        x86/compat: Adjust in_compat_syscall() to generic code under !COMPAT
        objtool: Support GCC 9 cold subfunction naming scheme
        x86/numa_emulation: Fix uniform-split numa emulation
        x86/paravirt: Remove unused _paravirt_ident_32
        x86/mm/pat: Disable preemption around __flush_tlb_all()
        x86/paravirt: Remove GPL from pv_ops export
        x86/traps: Use format string with panic() call
        x86: Clean up 'sizeof x' => 'sizeof(x)'
        x86/cpufeatures: Enumerate MOVDIR64B instruction
        x86/cpufeatures: Enumerate MOVDIRI instruction
        x86/earlyprintk: Add a force option for pciserial device
        objtool: Support per-function rodata sections
        x86/microcode: Make revision and processor flags world-readable
    • Linus Torvalds's avatar
      Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · 01897f3e
      Linus Torvalds authored
      Pull perf updates and fixes from Ingo Molnar:
       "These are almost all tooling updates: 'perf top', 'perf trace' and
        'perf script' fixes and updates, an UAPI header sync with the merge
        window versions, license marker updates, much improved Sparc support
        from David Miller, and a number of fixes"
      * 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (66 commits)
        perf intel-pt/bts: Calculate cpumode for synthesized samples
        perf intel-pt: Insert callchain context into synthesized callchains
        perf tools: Don't clone maps from parent when synthesizing forks
        perf top: Start display thread earlier
        tools headers uapi: Update linux/if_link.h header copy
        tools headers uapi: Update linux/netlink.h header copy
        tools headers: Sync the various kvm.h header copies
        tools include uapi: Update linux/mmap.h copy
        perf trace beauty: Use the mmap flags table generated from headers
        perf beauty: Wire up the mmap flags table generator to the Makefile
        perf beauty: Add a generator for MAP_ mmap's flag constants
        tools include uapi: Update asound.h copy
        tools arch uapi: Update asm-generic/unistd.h and arm64 unistd.h copies
        tools include uapi: Update linux/fs.h copy
        perf callchain: Honour the ordering of PERF_CONTEXT_{USER,KERNEL,etc}
        perf cs-etm: Correct CPU mode for samples
        perf unwind: Take pgoff into account when reporting elf to libdwfl
        perf top: Do not use overwrite mode by default
        perf top: Allow disabling the overwrite mode
        perf trace: Beautify mount's first pathname arg
    • Linus Torvalds's avatar
      Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · e9ebc215
      Linus Torvalds authored
      Pull irq fixes from Ingo Molnar:
       "An irqchip driver fix and a memory (over-)allocation fix"
      * 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        irqchip/irq-mvebu-sei: Fix a NULL vs IS_ERR() bug in probe function
        irq/matrix: Fix memory overallocation
  3. 03 Nov, 2018 27 commits