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Author SHA1 Message Date
Srinivasarao P
79de04d806 Merge android-4.4.148 (f057ff9) into msm-4.4
* refs/heads/tmp-f057ff9
  Linux 4.4.148
  x86/speculation/l1tf: Unbreak !__HAVE_ARCH_PFN_MODIFY_ALLOWED architectures
  x86/init: fix build with CONFIG_SWAP=n
  x86/speculation/l1tf: Fix up CPU feature flags
  x86/mm/kmmio: Make the tracer robust against L1TF
  x86/mm/pat: Make set_memory_np() L1TF safe
  x86/speculation/l1tf: Make pmd/pud_mknotpresent() invert
  x86/speculation/l1tf: Invert all not present mappings
  x86/speculation/l1tf: Fix up pte->pfn conversion for PAE
  x86/speculation/l1tf: Protect PAE swap entries against L1TF
  x86/cpufeatures: Add detection of L1D cache flush support.
  x86/speculation/l1tf: Extend 64bit swap file size limit
  x86/bugs: Move the l1tf function and define pr_fmt properly
  x86/speculation/l1tf: Limit swap file size to MAX_PA/2
  x86/speculation/l1tf: Disallow non privileged high MMIO PROT_NONE mappings
  mm: fix cache mode tracking in vm_insert_mixed()
  mm: Add vm_insert_pfn_prot()
  x86/speculation/l1tf: Add sysfs reporting for l1tf
  x86/speculation/l1tf: Make sure the first page is always reserved
  x86/speculation/l1tf: Protect PROT_NONE PTEs against speculation
  x86/speculation/l1tf: Protect swap entries against L1TF
  x86/speculation/l1tf: Change order of offset/type in swap entry
  mm: x86: move _PAGE_SWP_SOFT_DIRTY from bit 7 to bit 1
  x86/mm: Fix swap entry comment and macro
  x86/mm: Move swap offset/type up in PTE to work around erratum
  x86/speculation/l1tf: Increase 32bit PAE __PHYSICAL_PAGE_SHIFT
  x86/irqflags: Provide a declaration for native_save_fl
  kprobes/x86: Fix %p uses in error messages
  x86/speculation: Protect against userspace-userspace spectreRSB
  x86/paravirt: Fix spectre-v2 mitigations for paravirt guests
  ARM: dts: imx6sx: fix irq for pcie bridge
  IB/ocrdma: fix out of bounds access to local buffer
  IB/mlx4: Mark user MR as writable if actual virtual memory is writable
  IB/core: Make testing MR flags for writability a static inline function
  fix __legitimize_mnt()/mntput() race
  fix mntput/mntput race
  root dentries need RCU-delayed freeing
  scsi: sr: Avoid that opening a CD-ROM hangs with runtime power management enabled
  ACPI / LPSS: Add missing prv_offset setting for byt/cht PWM devices
  xen/netfront: don't cache skb_shinfo()
  parisc: Define mb() and add memory barriers to assembler unlock sequences
  parisc: Enable CONFIG_MLONGCALLS by default
  fork: unconditionally clear stack on fork
  ipv4+ipv6: Make INET*_ESP select CRYPTO_ECHAINIV
  tpm: fix race condition in tpm_common_write()
  ext4: fix check to prevent initializing reserved inodes
  Linux 4.4.147
  jfs: Fix inconsistency between memory allocation and ea_buf->max_size
  i2c: imx: Fix reinit_completion() use
  ring_buffer: tracing: Inherit the tracing setting to next ring buffer
  ACPI / PCI: Bail early in acpi_pci_add_bus() if there is no ACPI handle
  ext4: fix false negatives *and* false positives in ext4_check_descriptors()
  netlink: Don't shift on 64 for ngroups
  netlink: Don't shift with UB on nlk->ngroups
  netlink: Do not subscribe to non-existent groups
  nohz: Fix local_timer_softirq_pending()
  genirq: Make force irq threading setup more robust
  scsi: qla2xxx: Return error when TMF returns
  scsi: qla2xxx: Fix ISP recovery on unload

Conflicts:
	include/linux/swapfile.h

Removed CONFIG_CRYPTO_ECHAINIV from defconfig files since this upmerge is
adding this config to Kconfig file.

Change-Id: Ide96c29f919d76590c2bdccf356d1d464a892fd7
Signed-off-by: Srinivasarao P <spathi@codeaurora.org>
2018-08-24 00:07:01 +05:30
Greg Kroah-Hartman
f057ff9377 This is the 4.4.148 stable release
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Merge 4.4.148 into android-4.4

Changes in 4.4.148
	ext4: fix check to prevent initializing reserved inodes
	tpm: fix race condition in tpm_common_write()
	ipv4+ipv6: Make INET*_ESP select CRYPTO_ECHAINIV
	fork: unconditionally clear stack on fork
	parisc: Enable CONFIG_MLONGCALLS by default
	parisc: Define mb() and add memory barriers to assembler unlock sequences
	xen/netfront: don't cache skb_shinfo()
	ACPI / LPSS: Add missing prv_offset setting for byt/cht PWM devices
	scsi: sr: Avoid that opening a CD-ROM hangs with runtime power management enabled
	root dentries need RCU-delayed freeing
	fix mntput/mntput race
	fix __legitimize_mnt()/mntput() race
	IB/core: Make testing MR flags for writability a static inline function
	IB/mlx4: Mark user MR as writable if actual virtual memory is writable
	IB/ocrdma: fix out of bounds access to local buffer
	ARM: dts: imx6sx: fix irq for pcie bridge
	x86/paravirt: Fix spectre-v2 mitigations for paravirt guests
	x86/speculation: Protect against userspace-userspace spectreRSB
	kprobes/x86: Fix %p uses in error messages
	x86/irqflags: Provide a declaration for native_save_fl
	x86/speculation/l1tf: Increase 32bit PAE __PHYSICAL_PAGE_SHIFT
	x86/mm: Move swap offset/type up in PTE to work around erratum
	x86/mm: Fix swap entry comment and macro
	mm: x86: move _PAGE_SWP_SOFT_DIRTY from bit 7 to bit 1
	x86/speculation/l1tf: Change order of offset/type in swap entry
	x86/speculation/l1tf: Protect swap entries against L1TF
	x86/speculation/l1tf: Protect PROT_NONE PTEs against speculation
	x86/speculation/l1tf: Make sure the first page is always reserved
	x86/speculation/l1tf: Add sysfs reporting for l1tf
	mm: Add vm_insert_pfn_prot()
	mm: fix cache mode tracking in vm_insert_mixed()
	x86/speculation/l1tf: Disallow non privileged high MMIO PROT_NONE mappings
	x86/speculation/l1tf: Limit swap file size to MAX_PA/2
	x86/bugs: Move the l1tf function and define pr_fmt properly
	x86/speculation/l1tf: Extend 64bit swap file size limit
	x86/cpufeatures: Add detection of L1D cache flush support.
	x86/speculation/l1tf: Protect PAE swap entries against L1TF
	x86/speculation/l1tf: Fix up pte->pfn conversion for PAE
	x86/speculation/l1tf: Invert all not present mappings
	x86/speculation/l1tf: Make pmd/pud_mknotpresent() invert
	x86/mm/pat: Make set_memory_np() L1TF safe
	x86/mm/kmmio: Make the tracer robust against L1TF
	x86/speculation/l1tf: Fix up CPU feature flags
	x86/init: fix build with CONFIG_SWAP=n
	x86/speculation/l1tf: Unbreak !__HAVE_ARCH_PFN_MODIFY_ALLOWED architectures
	Linux 4.4.148

Change-Id: I83c857d9d9d74ee47e61d15eb411f276f057ba3d
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
2018-08-15 18:20:41 +02:00
Al Viro
b9341f5aeb fix __legitimize_mnt()/mntput() race
commit 119e1ef80ecfe0d1deb6378d4ab41f5b71519de1 upstream.

__legitimize_mnt() has two problems - one is that in case of success
the check of mount_lock is not ordered wrt preceding increment of
refcount, making it possible to have successful __legitimize_mnt()
on one CPU just before the otherwise final mntpu() on another,
with __legitimize_mnt() not seeing mntput() taking the lock and
mntput() not seeing the increment done by __legitimize_mnt().
Solved by a pair of barriers.

Another is that failure of __legitimize_mnt() on the second
read_seqretry() leaves us with reference that'll need to be
dropped by caller; however, if that races with final mntput()
we can end up with caller dropping rcu_read_lock() and doing
mntput() to release that reference - with the first mntput()
having freed the damn thing just as rcu_read_lock() had been
dropped.  Solution: in "do mntput() yourself" failure case
grab mount_lock, check if MNT_DOOMED has been set by racing
final mntput() that has missed our increment and if it has -
undo the increment and treat that as "failure, caller doesn't
need to drop anything" case.

It's not easy to hit - the final mntput() has to come right
after the first read_seqretry() in __legitimize_mnt() *and*
manage to miss the increment done by __legitimize_mnt() before
the second read_seqretry() in there.  The things that are almost
impossible to hit on bare hardware are not impossible on SMP
KVM, though...

Reported-by: Oleg Nesterov <oleg@redhat.com>
Fixes: 48a066e72d ("RCU'd vsfmounts")
Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-08-15 17:42:05 +02:00
Al Viro
a3ababd599 fix mntput/mntput race
commit 9ea0a46ca2c318fcc449c1e6b62a7230a17888f1 upstream.

mntput_no_expire() does the calculation of total refcount under mount_lock;
unfortunately, the decrement (as well as all increments) are done outside
of it, leading to false positives in the "are we dropping the last reference"
test.  Consider the following situation:
	* mnt is a lazy-umounted mount, kept alive by two opened files.  One
of those files gets closed.  Total refcount of mnt is 2.  On CPU 42
mntput(mnt) (called from __fput()) drops one reference, decrementing component
	* After it has looked at component #0, the process on CPU 0 does
mntget(), incrementing component #0, gets preempted and gets to run again -
on CPU 69.  There it does mntput(), which drops the reference (component #69)
and proceeds to spin on mount_lock.
	* On CPU 42 our first mntput() finishes counting.  It observes the
decrement of component #69, but not the increment of component #0.  As the
result, the total it gets is not 1 as it should've been - it's 0.  At which
point we decide that vfsmount needs to be killed and proceed to free it and
shut the filesystem down.  However, there's still another opened file
on that filesystem, with reference to (now freed) vfsmount, etc. and we are
screwed.

It's not a wide race, but it can be reproduced with artificial slowdown of
the mnt_get_count() loop, and it should be easier to hit on SMP KVM setups.

Fix consists of moving the refcount decrement under mount_lock; the tricky
part is that we want (and can) keep the fast case (i.e. mount that still
has non-NULL ->mnt_ns) entirely out of mount_lock.  All places that zero
mnt->mnt_ns are dropping some reference to mnt and they call synchronize_rcu()
before that mntput().  IOW, if mntput() observes (under rcu_read_lock())
a non-NULL ->mnt_ns, it is guaranteed that there is another reference yet to
be dropped.

Reported-by: Jann Horn <jannh@google.com>
Tested-by: Jann Horn <jannh@google.com>
Fixes: 48a066e72d ("RCU'd vsfmounts")
Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-08-15 17:42:05 +02:00
Srinivasarao P
ee76c85f71 Merge android-4.4.129 (b1c4836) into msm-4.4
* refs/heads/tmp-b1c4836
  Linux 4.4.129
  writeback: safer lock nesting
  fanotify: fix logic of events on child
  ext4: bugfix for mmaped pages in mpage_release_unused_pages()
  mm/filemap.c: fix NULL pointer in page_cache_tree_insert()
  mm: allow GFP_{FS,IO} for page_cache_read page cache allocation
  autofs: mount point create should honour passed in mode
  Don't leak MNT_INTERNAL away from internal mounts
  rpc_pipefs: fix double-dput()
  hypfs_kill_super(): deal with failed allocations
  jffs2_kill_sb(): deal with failed allocations
  powerpc/lib: Fix off-by-one in alternate feature patching
  powerpc/eeh: Fix enabling bridge MMIO windows
  MIPS: memset.S: Fix clobber of v1 in last_fixup
  MIPS: memset.S: Fix return of __clear_user from Lpartial_fixup
  MIPS: memset.S: EVA & fault support for small_memset
  MIPS: uaccess: Add micromips clobbers to bzero invocation
  HID: hidraw: Fix crash on HIDIOCGFEATURE with a destroyed device
  ALSA: hda - New VIA controller suppor no-snoop path
  ALSA: rawmidi: Fix missing input substream checks in compat ioctls
  ALSA: line6: Use correct endpoint type for midi output
  ext4: fix deadlock between inline_data and ext4_expand_extra_isize_ea()
  ext4: fix crashes in dioread_nolock mode
  drm/radeon: Fix PCIe lane width calculation
  ext4: don't allow r/w mounts if metadata blocks overlap the superblock
  vfio/pci: Virtualize Maximum Read Request Size
  vfio/pci: Virtualize Maximum Payload Size
  vfio-pci: Virtualize PCIe & AF FLR
  ALSA: pcm: Fix endless loop for XRUN recovery in OSS emulation
  ALSA: pcm: Fix mutex unbalance in OSS emulation ioctls
  ALSA: pcm: Return -EBUSY for OSS ioctls changing busy streams
  ALSA: pcm: Avoid potential races between OSS ioctls and read/write
  ALSA: pcm: Use ERESTARTSYS instead of EINTR in OSS emulation
  ALSA: oss: consolidate kmalloc/memset 0 call to kzalloc
  watchdog: f71808e_wdt: Fix WD_EN register read
  thermal: imx: Fix race condition in imx_thermal_probe()
  clk: bcm2835: De-assert/assert PLL reset signal when appropriate
  clk: mvebu: armada-38x: add support for missing clocks
  clk: mvebu: armada-38x: add support for 1866MHz variants
  mmc: jz4740: Fix race condition in IRQ mask update
  iommu/vt-d: Fix a potential memory leak
  um: Use POSIX ucontext_t instead of struct ucontext
  dmaengine: at_xdmac: fix rare residue corruption
  IB/srp: Fix completion vector assignment algorithm
  IB/srp: Fix srp_abort()
  ALSA: pcm: Fix UAF at PCM release via PCM timer access
  RDMA/ucma: Don't allow setting RDMA_OPTION_IB_PATH without an RDMA device
  ext4: fail ext4_iget for root directory if unallocated
  ext4: don't update checksum of new initialized bitmaps
  jbd2: if the journal is aborted then don't allow update of the log tail
  random: use a tighter cap in credit_entropy_bits_safe()
  thunderbolt: Resume control channel after hibernation image is created
  ASoC: ssm2602: Replace reg_default_raw with reg_default
  HID: core: Fix size as type u32
  HID: Fix hid_report_len usage
  powerpc/powernv: Fix OPAL NVRAM driver OPAL_BUSY loops
  powerpc/powernv: define a standard delay for OPAL_BUSY type retry loops
  powerpc/64: Fix smp_wmb barrier definition use use lwsync consistently
  powerpc/powernv: Handle unknown OPAL errors in opal_nvram_write()
  HID: i2c-hid: fix size check and type usage
  usb: dwc3: pci: Properly cleanup resource
  USB:fix USB3 devices behind USB3 hubs not resuming at hibernate thaw
  ACPI / hotplug / PCI: Check presence of slot itself in get_slot_status()
  ACPI / video: Add quirk to force acpi-video backlight on Samsung 670Z5E
  regmap: Fix reversed bounds check in regmap_raw_write()
  xen-netfront: Fix hang on device removal
  ARM: dts: at91: sama5d4: fix pinctrl compatible string
  ARM: dts: at91: at91sam9g25: fix mux-mask pinctrl property
  usb: musb: gadget: misplaced out of bounds check
  mm, slab: reschedule cache_reap() on the same CPU
  ipc/shm: fix use-after-free of shm file via remap_file_pages()
  resource: fix integer overflow at reallocation
  fs/reiserfs/journal.c: add missing resierfs_warning() arg
  ubi: Reject MLC NAND
  ubi: Fix error for write access
  ubi: fastmap: Don't flush fastmap work on detach
  ubifs: Check ubifs_wbuf_sync() return code
  tty: make n_tty_read() always abort if hangup is in progress
  x86/hweight: Don't clobber %rdi
  x86/hweight: Get rid of the special calling convention
  lan78xx: Correctly indicate invalid OTP
  slip: Check if rstate is initialized before uncompressing
  cdc_ether: flag the Cinterion AHS8 modem by gemalto as WWAN
  hwmon: (ina2xx) Fix access to uninitialized mutex
  rtl8187: Fix NULL pointer dereference in priv->conf_mutex
  getname_kernel() needs to make sure that ->name != ->iname in long case
  s390/ipl: ensure loadparm valid flag is set
  s390/qdio: don't merge ERROR output buffers
  s390/qdio: don't retry EQBS after CCQ 96
  block/loop: fix deadlock after loop_set_status
  Revert "perf tests: Decompress kernel module before objdump"
  radeon: hide pointless #warning when compile testing
  perf intel-pt: Fix timestamp following overflow
  perf intel-pt: Fix error recovery from missing TIP packet
  perf intel-pt: Fix sync_switch
  perf intel-pt: Fix overlap detection to identify consecutive buffers correctly
  parisc: Fix out of array access in match_pci_device()
  media: v4l2-compat-ioctl32: don't oops on overlay
  f2fs: check cap_resource only for data blocks
  Revert "f2fs: introduce f2fs_set_page_dirty_nobuffer"
  f2fs: clear PageError on writepage
  UPSTREAM: timer: Export destroy_hrtimer_on_stack()
  BACKPORT: dm verity: add 'check_at_most_once' option to only validate hashes once
  f2fs: call unlock_new_inode() before d_instantiate()
  f2fs: refactor read path to allow multiple postprocessing steps
  fscrypt: allow synchronous bio decryption

Change-Id: I45f4ac10734d92023b53118d83dcd6c83974a283
Signed-off-by: Srinivasarao P <spathi@codeaurora.org>
2018-04-24 19:07:57 +05:30
Greg Kroah-Hartman
b1c4836e57 This is the 4.4.129 stable release
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Merge 4.4.129 into android-4.4

Changes in 4.4.129
	media: v4l2-compat-ioctl32: don't oops on overlay
	parisc: Fix out of array access in match_pci_device()
	perf intel-pt: Fix overlap detection to identify consecutive buffers correctly
	perf intel-pt: Fix sync_switch
	perf intel-pt: Fix error recovery from missing TIP packet
	perf intel-pt: Fix timestamp following overflow
	radeon: hide pointless #warning when compile testing
	Revert "perf tests: Decompress kernel module before objdump"
	block/loop: fix deadlock after loop_set_status
	s390/qdio: don't retry EQBS after CCQ 96
	s390/qdio: don't merge ERROR output buffers
	s390/ipl: ensure loadparm valid flag is set
	getname_kernel() needs to make sure that ->name != ->iname in long case
	rtl8187: Fix NULL pointer dereference in priv->conf_mutex
	hwmon: (ina2xx) Fix access to uninitialized mutex
	cdc_ether: flag the Cinterion AHS8 modem by gemalto as WWAN
	slip: Check if rstate is initialized before uncompressing
	lan78xx: Correctly indicate invalid OTP
	x86/hweight: Get rid of the special calling convention
	x86/hweight: Don't clobber %rdi
	tty: make n_tty_read() always abort if hangup is in progress
	ubifs: Check ubifs_wbuf_sync() return code
	ubi: fastmap: Don't flush fastmap work on detach
	ubi: Fix error for write access
	ubi: Reject MLC NAND
	fs/reiserfs/journal.c: add missing resierfs_warning() arg
	resource: fix integer overflow at reallocation
	ipc/shm: fix use-after-free of shm file via remap_file_pages()
	mm, slab: reschedule cache_reap() on the same CPU
	usb: musb: gadget: misplaced out of bounds check
	ARM: dts: at91: at91sam9g25: fix mux-mask pinctrl property
	ARM: dts: at91: sama5d4: fix pinctrl compatible string
	xen-netfront: Fix hang on device removal
	regmap: Fix reversed bounds check in regmap_raw_write()
	ACPI / video: Add quirk to force acpi-video backlight on Samsung 670Z5E
	ACPI / hotplug / PCI: Check presence of slot itself in get_slot_status()
	USB:fix USB3 devices behind USB3 hubs not resuming at hibernate thaw
	usb: dwc3: pci: Properly cleanup resource
	HID: i2c-hid: fix size check and type usage
	powerpc/powernv: Handle unknown OPAL errors in opal_nvram_write()
	powerpc/64: Fix smp_wmb barrier definition use use lwsync consistently
	powerpc/powernv: define a standard delay for OPAL_BUSY type retry loops
	powerpc/powernv: Fix OPAL NVRAM driver OPAL_BUSY loops
	HID: Fix hid_report_len usage
	HID: core: Fix size as type u32
	ASoC: ssm2602: Replace reg_default_raw with reg_default
	thunderbolt: Resume control channel after hibernation image is created
	random: use a tighter cap in credit_entropy_bits_safe()
	jbd2: if the journal is aborted then don't allow update of the log tail
	ext4: don't update checksum of new initialized bitmaps
	ext4: fail ext4_iget for root directory if unallocated
	RDMA/ucma: Don't allow setting RDMA_OPTION_IB_PATH without an RDMA device
	ALSA: pcm: Fix UAF at PCM release via PCM timer access
	IB/srp: Fix srp_abort()
	IB/srp: Fix completion vector assignment algorithm
	dmaengine: at_xdmac: fix rare residue corruption
	um: Use POSIX ucontext_t instead of struct ucontext
	iommu/vt-d: Fix a potential memory leak
	mmc: jz4740: Fix race condition in IRQ mask update
	clk: mvebu: armada-38x: add support for 1866MHz variants
	clk: mvebu: armada-38x: add support for missing clocks
	clk: bcm2835: De-assert/assert PLL reset signal when appropriate
	thermal: imx: Fix race condition in imx_thermal_probe()
	watchdog: f71808e_wdt: Fix WD_EN register read
	ALSA: oss: consolidate kmalloc/memset 0 call to kzalloc
	ALSA: pcm: Use ERESTARTSYS instead of EINTR in OSS emulation
	ALSA: pcm: Avoid potential races between OSS ioctls and read/write
	ALSA: pcm: Return -EBUSY for OSS ioctls changing busy streams
	ALSA: pcm: Fix mutex unbalance in OSS emulation ioctls
	ALSA: pcm: Fix endless loop for XRUN recovery in OSS emulation
	vfio-pci: Virtualize PCIe & AF FLR
	vfio/pci: Virtualize Maximum Payload Size
	vfio/pci: Virtualize Maximum Read Request Size
	ext4: don't allow r/w mounts if metadata blocks overlap the superblock
	drm/radeon: Fix PCIe lane width calculation
	ext4: fix crashes in dioread_nolock mode
	ext4: fix deadlock between inline_data and ext4_expand_extra_isize_ea()
	ALSA: line6: Use correct endpoint type for midi output
	ALSA: rawmidi: Fix missing input substream checks in compat ioctls
	ALSA: hda - New VIA controller suppor no-snoop path
	HID: hidraw: Fix crash on HIDIOCGFEATURE with a destroyed device
	MIPS: uaccess: Add micromips clobbers to bzero invocation
	MIPS: memset.S: EVA & fault support for small_memset
	MIPS: memset.S: Fix return of __clear_user from Lpartial_fixup
	MIPS: memset.S: Fix clobber of v1 in last_fixup
	powerpc/eeh: Fix enabling bridge MMIO windows
	powerpc/lib: Fix off-by-one in alternate feature patching
	jffs2_kill_sb(): deal with failed allocations
	hypfs_kill_super(): deal with failed allocations
	rpc_pipefs: fix double-dput()
	Don't leak MNT_INTERNAL away from internal mounts
	autofs: mount point create should honour passed in mode
	mm: allow GFP_{FS,IO} for page_cache_read page cache allocation
	mm/filemap.c: fix NULL pointer in page_cache_tree_insert()
	ext4: bugfix for mmaped pages in mpage_release_unused_pages()
	fanotify: fix logic of events on child
	writeback: safer lock nesting
	Linux 4.4.129

Change-Id: I8806d2cc92fe512f27a349e8f630ced0cac9a8d7
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
2018-04-24 10:42:34 +02:00
Al Viro
d10a274ada Don't leak MNT_INTERNAL away from internal mounts
commit 16a34adb9392b2fe4195267475ab5b472e55292c upstream.

We want it only for the stuff created by SB_KERNMOUNT mounts, *not* for
their copies.  As it is, creating a deep stack of bindings of /proc/*/ns/*
somewhere in a new namespace and exiting yields a stack overflow.

Cc: stable@kernel.org
Reported-by: Alexander Aring <aring@mojatatu.com>
Bisected-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Tested-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Tested-by: Alexander Aring <aring@mojatatu.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-04-24 09:32:11 +02:00
Blagovest Kolenichev
3e99b7f6eb Merge android-4.4@29d0b65 (v4.4.88) into msm-4.4
* refs/heads/tmp-29d0b65
  Linux 4.4.88
  xfs: XFS_IS_REALTIME_INODE() should be false if no rt device present
  NFS: Fix 2 use after free issues in the I/O code
  ARM: 8692/1: mm: abort uaccess retries upon fatal signal
  Bluetooth: Properly check L2CAP config option output buffer length
  ALSA: msnd: Optimize / harden DSP and MIDI loops
  locktorture: Fix potential memory leak with rw lock test
  btrfs: resume qgroup rescan on rw remount
  drm/bridge: adv7511: Re-write the i2c address before EDID probing
  drm/bridge: adv7511: Switch to using drm_kms_helper_hotplug_event()
  drm/bridge: adv7511: Use work_struct to defer hotplug handing to out of irq context
  drm/bridge: adv7511: Fix mutex deadlock when interrupts are disabled
  drm: adv7511: really enable interrupts for EDID detection
  scsi: sg: recheck MMAP_IO request length with lock held
  scsi: sg: protect against races between mmap() and SG_SET_RESERVED_SIZE
  cs5536: add support for IDE controller variant
  workqueue: Fix flag collision
  drm/nouveau/pci/msi: disable MSI on big-endian platforms by default
  mwifiex: correct channel stat buffer overflows
  dlm: avoid double-free on error path in dlm_device_{register,unregister}
  Bluetooth: Add support of 13d3:3494 RTL8723BE device
  rtlwifi: rtl_pci_probe: Fix fail path of _rtl_pci_find_adapter
  Input: trackpoint - assume 3 buttons when buttons detection fails
  ath10k: fix memory leak in rx ring buffer allocation
  intel_th: pci: Add Cannon Lake PCH-LP support
  intel_th: pci: Add Cannon Lake PCH-H support
  driver core: bus: Fix a potential double free
  staging/rts5208: fix incorrect shift to extract upper nybble
  USB: core: Avoid race of async_completed() w/ usbdev_release()
  usb:xhci:Fix regression when ATI chipsets detected
  usb: Add device quirk for Logitech HD Pro Webcam C920-C
  USB: serial: option: add support for D-Link DWM-157 C1
  usb: quirks: add delay init quirk for Corsair Strafe RGB keyboard
  ANDROID: sdcardfs: Add missing break
  ANDROID: Sdcardfs: Move gid derivation under flag
  ANDROID: mnt: Fix freeing of mount data
  drivers: cpufreq: checks to avoid kernel crash in cpufreq_interactive
  ANDROID: Use sk_uid to replace uid get from socket file
  ANDROID: nf: xt_qtaguid: fix handling for cases where tunnels are used.
  Revert "ANDROID: Use sk_uid to replace uid get from socket file"
  ANDROID: fiq_debugger: Fix minor bug in code

Conflicts:
	drivers/cpufreq/cpufreq_interactive.c
	drivers/net/wireless/ath/ath10k/core.c
	drivers/staging/android/fiq_debugger/fiq_debugger.c
	net/netfilter/xt_qtaguid.c

Change-Id: I49c67ff84d4bee0799691cc1ee0a023e2dd13e66
Signed-off-by: Blagovest Kolenichev <bkolenichev@codeaurora.org>
2017-09-21 14:00:18 -07:00
Daniel Rosenberg
e698796fd2 ANDROID: mnt: Fix freeing of mount data
Fix double free on error paths

Signed-off-by: Daniel Rosenberg <drosen@google.com>
Change-Id: I1c25a175e87e5dd5cafcdcf9d78bf4c0dc3f88ef
Bug: 65386954
Fixes: 6b42d02561 ("ANDROID: mnt: Add filesystem private data to mount points")
2017-09-08 20:38:02 +00:00
Linux Build Service Account
cb10479cfa Merge "Merge android-4.4@59ff2e1 (v4.4.78) into msm-4.4" 2017-08-08 09:02:16 -07:00
Greg Kroah-Hartman
59ff2e15be This is the 4.4.78 stable release
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Merge 4.4.78 into android-4.4

Changes in 4.4.78
	net_sched: fix error recovery at qdisc creation
	net: sched: Fix one possible panic when no destroy callback
	net/phy: micrel: configure intterupts after autoneg workaround
	ipv6: avoid unregistering inet6_dev for loopback
	net: dp83640: Avoid NULL pointer dereference.
	tcp: reset sk_rx_dst in tcp_disconnect()
	net: prevent sign extension in dev_get_stats()
	bpf: prevent leaking pointer via xadd on unpriviledged
	net: handle NAPI_GRO_FREE_STOLEN_HEAD case also in napi_frags_finish()
	ipv6: dad: don't remove dynamic addresses if link is down
	net: ipv6: Compare lwstate in detecting duplicate nexthops
	vrf: fix bug_on triggered by rx when destroying a vrf
	rds: tcp: use sock_create_lite() to create the accept socket
	brcmfmac: fix possible buffer overflow in brcmf_cfg80211_mgmt_tx()
	cfg80211: Define nla_policy for NL80211_ATTR_LOCAL_MESH_POWER_MODE
	cfg80211: Validate frequencies nested in NL80211_ATTR_SCAN_FREQUENCIES
	cfg80211: Check if PMKID attribute is of expected size
	irqchip/gic-v3: Fix out-of-bound access in gic_set_affinity
	parisc: Report SIGSEGV instead of SIGBUS when running out of stack
	parisc: use compat_sys_keyctl()
	parisc: DMA API: return error instead of BUG_ON for dma ops on non dma devs
	parisc/mm: Ensure IRQs are off in switch_mm()
	tools/lib/lockdep: Reduce MAX_LOCK_DEPTH to avoid overflowing lock_chain/: Depth
	kernel/extable.c: mark core_kernel_text notrace
	mm/list_lru.c: fix list_lru_count_node() to be race free
	fs/dcache.c: fix spin lockup issue on nlru->lock
	checkpatch: silence perl 5.26.0 unescaped left brace warnings
	binfmt_elf: use ELF_ET_DYN_BASE only for PIE
	arm: move ELF_ET_DYN_BASE to 4MB
	arm64: move ELF_ET_DYN_BASE to 4GB / 4MB
	powerpc: move ELF_ET_DYN_BASE to 4GB / 4MB
	s390: reduce ELF_ET_DYN_BASE
	exec: Limit arg stack to at most 75% of _STK_LIM
	vt: fix unchecked __put_user() in tioclinux ioctls
	mnt: In umount propagation reparent in a separate pass
	mnt: In propgate_umount handle visiting mounts in any order
	mnt: Make propagate_umount less slow for overlapping mount propagation trees
	selftests/capabilities: Fix the test_execve test
	tpm: Get rid of chip->pdev
	tpm: Provide strong locking for device removal
	Add "shutdown" to "struct class".
	tpm: Issue a TPM2_Shutdown for TPM2 devices.
	mm: fix overflow check in expand_upwards()
	crypto: talitos - Extend max key length for SHA384/512-HMAC and AEAD
	crypto: atmel - only treat EBUSY as transient if backlog
	crypto: sha1-ssse3 - Disable avx2
	crypto: caam - fix signals handling
	sched/topology: Fix overlapping sched_group_mask
	sched/topology: Optimize build_group_mask()
	PM / wakeirq: Convert to SRCU
	PM / QoS: return -EINVAL for bogus strings
	tracing: Use SOFTIRQ_OFFSET for softirq dectection for more accurate results
	KVM: x86: disable MPX if host did not enable MPX XSAVE features
	kvm: vmx: Do not disable intercepts for BNDCFGS
	kvm: x86: Guest BNDCFGS requires guest MPX support
	kvm: vmx: Check value written to IA32_BNDCFGS
	kvm: vmx: allow host to access guest MSR_IA32_BNDCFGS
	Linux 4.4.78

Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
2017-07-21 09:14:57 +02:00
Eric W. Biederman
fdb8f10499 mnt: In propgate_umount handle visiting mounts in any order
commit 99b19d16471e9c3faa85cad38abc9cbbe04c6d55 upstream.

While investigating some poor umount performance I realized that in
the case of overlapping mount trees where some of the mounts are locked
the code has been failing to unmount all of the mounts it should
have been unmounting.

This failure to unmount all of the necessary
mounts can be reproduced with:

$ cat locked_mounts_test.sh

mount -t tmpfs test-base /mnt
mount --make-shared /mnt
mkdir -p /mnt/b

mount -t tmpfs test1 /mnt/b
mount --make-shared /mnt/b
mkdir -p /mnt/b/10

mount -t tmpfs test2 /mnt/b/10
mount --make-shared /mnt/b/10
mkdir -p /mnt/b/10/20

mount --rbind /mnt/b /mnt/b/10/20

unshare -Urm --propagation unchaged /bin/sh -c 'sleep 5; if [ $(grep test /proc/self/mountinfo | wc -l) -eq 1 ] ; then echo SUCCESS ; else echo FAILURE ; fi'
sleep 1
umount -l /mnt/b
wait %%

$ unshare -Urm ./locked_mounts_test.sh

This failure is corrected by removing the prepass that marks mounts
that may be umounted.

A first pass is added that umounts mounts if possible and if not sets
mount mark if they could be unmounted if they weren't locked and adds
them to a list to umount possibilities.  This first pass reconsiders
the mounts parent if it is on the list of umount possibilities, ensuring
that information of umoutability will pass from child to mount parent.

A second pass then walks through all mounts that are umounted and processes
their children unmounting them or marking them for reparenting.

A last pass cleans up the state on the mounts that could not be umounted
and if applicable reparents them to their first parent that remained
mounted.

While a bit longer than the old code this code is much more robust
as it allows information to flow up from the leaves and down
from the trunk making the order in which mounts are encountered
in the umount propgation tree irrelevant.

Fixes: 0c56fe3142 ("mnt: Don't propagate unmounts to locked mounts")
Reviewed-by: Andrei Vagin <avagin@virtuozzo.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-07-21 07:44:57 +02:00
Eric W. Biederman
7cbc3955ef mnt: In umount propagation reparent in a separate pass
commit 570487d3faf2a1d8a220e6ee10f472163123d7da upstream.

It was observed that in some pathlogical cases that the current code
does not unmount everything it should.  After investigation it
was determined that the issue is that mnt_change_mntpoint can
can change which mounts are available to be unmounted during mount
propagation which is wrong.

The trivial reproducer is:
$ cat ./pathological.sh

mount -t tmpfs test-base /mnt
cd /mnt
mkdir 1 2 1/1
mount --bind 1 1
mount --make-shared 1
mount --bind 1 2
mount --bind 1/1 1/1
mount --bind 1/1 1/1
echo
grep test-base /proc/self/mountinfo
umount 1/1
echo
grep test-base /proc/self/mountinfo

$ unshare -Urm ./pathological.sh

The expected output looks like:
46 31 0:25 / /mnt rw,relatime - tmpfs test-base rw,uid=1000,gid=1000
47 46 0:25 /1 /mnt/1 rw,relatime shared:1 - tmpfs test-base rw,uid=1000,gid=1000
48 46 0:25 /1 /mnt/2 rw,relatime shared:1 - tmpfs test-base rw,uid=1000,gid=1000
49 54 0:25 /1/1 /mnt/1/1 rw,relatime shared:1 - tmpfs test-base rw,uid=1000,gid=1000
50 53 0:25 /1/1 /mnt/2/1 rw,relatime shared:1 - tmpfs test-base rw,uid=1000,gid=1000
51 49 0:25 /1/1 /mnt/1/1 rw,relatime shared:1 - tmpfs test-base rw,uid=1000,gid=1000
54 47 0:25 /1/1 /mnt/1/1 rw,relatime shared:1 - tmpfs test-base rw,uid=1000,gid=1000
53 48 0:25 /1/1 /mnt/2/1 rw,relatime shared:1 - tmpfs test-base rw,uid=1000,gid=1000
52 50 0:25 /1/1 /mnt/2/1 rw,relatime shared:1 - tmpfs test-base rw,uid=1000,gid=1000

46 31 0:25 / /mnt rw,relatime - tmpfs test-base rw,uid=1000,gid=1000
47 46 0:25 /1 /mnt/1 rw,relatime shared:1 - tmpfs test-base rw,uid=1000,gid=1000
48 46 0:25 /1 /mnt/2 rw,relatime shared:1 - tmpfs test-base rw,uid=1000,gid=1000

The output without the fix looks like:
46 31 0:25 / /mnt rw,relatime - tmpfs test-base rw,uid=1000,gid=1000
47 46 0:25 /1 /mnt/1 rw,relatime shared:1 - tmpfs test-base rw,uid=1000,gid=1000
48 46 0:25 /1 /mnt/2 rw,relatime shared:1 - tmpfs test-base rw,uid=1000,gid=1000
49 54 0:25 /1/1 /mnt/1/1 rw,relatime shared:1 - tmpfs test-base rw,uid=1000,gid=1000
50 53 0:25 /1/1 /mnt/2/1 rw,relatime shared:1 - tmpfs test-base rw,uid=1000,gid=1000
51 49 0:25 /1/1 /mnt/1/1 rw,relatime shared:1 - tmpfs test-base rw,uid=1000,gid=1000
54 47 0:25 /1/1 /mnt/1/1 rw,relatime shared:1 - tmpfs test-base rw,uid=1000,gid=1000
53 48 0:25 /1/1 /mnt/2/1 rw,relatime shared:1 - tmpfs test-base rw,uid=1000,gid=1000
52 50 0:25 /1/1 /mnt/2/1 rw,relatime shared:1 - tmpfs test-base rw,uid=1000,gid=1000

46 31 0:25 / /mnt rw,relatime - tmpfs test-base rw,uid=1000,gid=1000
47 46 0:25 /1 /mnt/1 rw,relatime shared:1 - tmpfs test-base rw,uid=1000,gid=1000
48 46 0:25 /1 /mnt/2 rw,relatime shared:1 - tmpfs test-base rw,uid=1000,gid=1000
52 48 0:25 /1/1 /mnt/2/1 rw,relatime shared:1 - tmpfs test-base rw,uid=1000,gid=1000

That last mount in the output was in the propgation tree to be unmounted but
was missed because the mnt_change_mountpoint changed it's parent before the walk
through the mount propagation tree observed it.

Fixes: 1064f874abc0 ("mnt: Tuck mounts under others instead of creating shadow/side mounts.")
Acked-by: Andrei Vagin <avagin@virtuozzo.com>
Reviewed-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-07-21 07:44:57 +02:00
Nikhilesh Reddy
1b4ccee624 vfs: Add support to debug umount failures
When umount of a partition fails with EBUSY there is
no indication as to what is keeping the mount point busy.

Add support to print a kernel log showing what files
are open on this mount point.

Also add a new new config option CONFIG_FILE_TABLE_DEBUG to
enable this feature.

Change-Id: Id7a3f5e7291b22ffd0f265848ec0a9757f713561
Signed-off-by: Nikhilesh Reddy <reddyn@codeaurora.org>
Signed-off-by: Ankit Jain <ankijain@codeaurora.org>
2017-07-17 11:39:09 +05:30
Greg Kroah-Hartman
e4528dd775 This is the 4.4.65 stable release
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Merge 4.4.65 into android-4.4

Changes in 4.4.65:
	tipc: make sure IPv6 header fits in skb headroom
	tipc: make dist queue pernet
	tipc: re-enable compensation for socket receive buffer double counting
	tipc: correct error in node fsm
	tty: nozomi: avoid a harmless gcc warning
	hostap: avoid uninitialized variable use in hfa384x_get_rid
	gfs2: avoid uninitialized variable warning
	tipc: fix random link resets while adding a second bearer
	tipc: fix socket timer deadlock
	mnt: Add a per mount namespace limit on the number of mounts
	xc2028: avoid use after free
	netfilter: nfnetlink: correctly validate length of batch messages
	tipc: check minimum bearer MTU
	vfio/pci: Fix integer overflows, bitmask check
	staging/android/ion : fix a race condition in the ion driver
	ping: implement proper locking
	perf/core: Fix concurrent sys_perf_event_open() vs. 'move_group' race
	Linux 4.4.65

Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
2017-04-30 07:30:52 +02:00
Eric W. Biederman
c50fd34e10 mnt: Add a per mount namespace limit on the number of mounts
commit d29216842a85c7970c536108e093963f02714498 upstream.

CAI Qian <caiqian@redhat.com> pointed out that the semantics
of shared subtrees make it possible to create an exponentially
increasing number of mounts in a mount namespace.

    mkdir /tmp/1 /tmp/2
    mount --make-rshared /
    for i in $(seq 1 20) ; do mount --bind /tmp/1 /tmp/2 ; done

Will create create 2^20 or 1048576 mounts, which is a practical problem
as some people have managed to hit this by accident.

As such CVE-2016-6213 was assigned.

Ian Kent <raven@themaw.net> described the situation for autofs users
as follows:

> The number of mounts for direct mount maps is usually not very large because of
> the way they are implemented, large direct mount maps can have performance
> problems. There can be anywhere from a few (likely case a few hundred) to less
> than 10000, plus mounts that have been triggered and not yet expired.
>
> Indirect mounts have one autofs mount at the root plus the number of mounts that
> have been triggered and not yet expired.
>
> The number of autofs indirect map entries can range from a few to the common
> case of several thousand and in rare cases up to between 30000 and 50000. I've
> not heard of people with maps larger than 50000 entries.
>
> The larger the number of map entries the greater the possibility for a large
> number of active mounts so it's not hard to expect cases of a 1000 or somewhat
> more active mounts.

So I am setting the default number of mounts allowed per mount
namespace at 100,000.  This is more than enough for any use case I
know of, but small enough to quickly stop an exponential increase
in mounts.  Which should be perfect to catch misconfigurations and
malfunctioning programs.

For anyone who needs a higher limit this can be changed by writing
to the new /proc/sys/fs/mount-max sysctl.

Tested-by: CAI Qian <caiqian@redhat.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
[bwh: Backported to 4.4: adjust context]
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-04-30 05:49:28 +02:00
Eric W. Biederman
cd237bd504 mnt: Tuck mounts under others instead of creating shadow/side mounts.
am: 839d42687d

Change-Id: Id06d474c7f7b46c1ce05056028ca02837cacf215
2017-03-15 02:10:19 +00:00
Eric W. Biederman
839d42687d mnt: Tuck mounts under others instead of creating shadow/side mounts.
commit 1064f874abc0d05eeed8993815f584d847b72486 upstream.

Ever since mount propagation was introduced in cases where a mount in
propagated to parent mount mountpoint pair that is already in use the
code has placed the new mount behind the old mount in the mount hash
table.

This implementation detail is problematic as it allows creating
arbitrary length mount hash chains.

Furthermore it invalidates the constraint maintained elsewhere in the
mount code that a parent mount and a mountpoint pair will have exactly
one mount upon them.  Making it hard to deal with and to talk about
this special case in the mount code.

Modify mount propagation to notice when there is already a mount at
the parent mount and mountpoint where a new mount is propagating to
and place that preexisting mount on top of the new mount.

Modify unmount propagation to notice when a mount that is being
unmounted has another mount on top of it (and no other children), and
to replace the unmounted mount with the mount on top of it.

Move the MNT_UMUONT test from __lookup_mnt_last into
__propagate_umount as that is the only call of __lookup_mnt_last where
MNT_UMOUNT may be set on any mount visible in the mount hash table.

These modifications allow:
 - __lookup_mnt_last to be removed.
 - attach_shadows to be renamed __attach_mnt and its shadow
   handling to be removed.
 - commit_tree to be simplified
 - copy_tree to be simplified

The result is an easier to understand tree of mounts that does not
allow creation of arbitrary length hash chains in the mount hash table.

The result is also a very slight userspace visible difference in semantics.
The following two cases now behave identically, where before order
mattered:

case 1: (explicit user action)
	B is a slave of A
	mount something on A/a , it will propagate to B/a
	and than mount something on B/a

case 2: (tucked mount)
	B is a slave of A
	mount something on B/a
	and than mount something on A/a

Histroically umount A/a would fail in case 1 and succeed in case 2.
Now umount A/a succeeds in both configurations.

This very small change in semantics appears if anything to be a bug
fix to me and my survey of userspace leads me to believe that no programs
will notice or care of this subtle semantic change.

v2: Updated to mnt_change_mountpoint to not call dput or mntput
and instead to decrement the counts directly.  It is guaranteed
that there will be other references when mnt_change_mountpoint is
called so this is safe.

v3: Moved put_mountpoint under mount_lock in attach_recursive_mnt
    As the locking in fs/namespace.c changed between v2 and v3.

v4: Reworked the logic in propagate_mount_busy and __propagate_umount
    that detects when a mount completely covers another mount.

v5: Removed unnecessary tests whose result is alwasy true in
    find_topper and attach_recursive_mnt.

v6: Document the user space visible semantic difference.

Fixes: b90fa9ae8f ("[PATCH] shared mount handling: bind and rbind")
Tested-by: Andrei Vagin <avagin@virtuozzo.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-03-15 09:57:13 +08:00
Dmitry Shmidt
232c28fe23 Merge remote-tracking branch 'common/android-4.4' into android-4.4.y
Change-Id: Icf907f5067fb6da5935ab0d3271df54b8d5df405
2017-02-15 18:02:55 -08:00
Daniel Rosenberg
0ad2dd493c ANDROID: vfs: Allow filesystems to access their private mount data
Now we pass the vfsmount when mounting and remounting.
This allows the filesystem to actually set up the mount
specific data, although we can't quite do anything with
it yet. show_options is expanded to include data that
lives with the mount.

To avoid changing existing filesystems, these have
been added as new vfs functions.

Change-Id: If80670bfad9f287abb8ac22457e1b034c9697097
Signed-off-by: Daniel Rosenberg <drosen@google.com>
2017-01-26 15:53:30 -08:00
Daniel Rosenberg
6b42d02561 ANDROID: mnt: Add filesystem private data to mount points
This starts to add private data associated directly
to mount points. The intent is to give filesystems
a sense of where they have come from, as a means of
letting a filesystem take different actions based on
this information.

Change-Id: Ie769d7b3bb2f5972afe05c1bf16cf88c91647ab2
Signed-off-by: Daniel Rosenberg <drosen@google.com>
2017-01-26 15:53:30 -08:00
Eric W. Biederman
4a6716f165 mnt: Protect the mountpoint hashtable with mount_lock
commit 3895dbf8985f656675b5bde610723a29cbce3fa7 upstream.

Protecting the mountpoint hashtable with namespace_sem was sufficient
until a call to umount_mnt was added to mntput_no_expire.  At which
point it became possible for multiple calls of put_mountpoint on
the same hash chain to happen on the same time.

Kristen Johansen <kjlx@templeofstupid.com> reported:
> This can cause a panic when simultaneous callers of put_mountpoint
> attempt to free the same mountpoint.  This occurs because some callers
> hold the mount_hash_lock, while others hold the namespace lock.  Some
> even hold both.
>
> In this submitter's case, the panic manifested itself as a GP fault in
> put_mountpoint() when it called hlist_del() and attempted to dereference
> a m_hash.pprev that had been poisioned by another thread.

Al Viro observed that the simple fix is to switch from using the namespace_sem
to the mount_lock to protect the mountpoint hash table.

I have taken Al's suggested patch moved put_mountpoint in pivot_root
(instead of taking mount_lock an additional time), and have replaced
new_mountpoint with get_mountpoint a function that does the hash table
lookup and addition under the mount_lock.   The introduction of get_mounptoint
ensures that only the mount_lock is needed to manipulate the mountpoint
hashtable.

d_set_mounted is modified to only set DCACHE_MOUNTED if it is not
already set.  This allows get_mountpoint to use the setting of
DCACHE_MOUNTED to ensure adding a struct mountpoint for a dentry
happens exactly once.

Fixes: ce07d891a0 ("mnt: Honor MNT_LOCKED when detaching mounts")
Reported-by: Krister Johansen <kjlx@templeofstupid.com>
Suggested-by: Al Viro <viro@ZenIV.linux.org.uk>
Acked-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-01-19 20:17:21 +01:00
Andrey Ulanov
df582d4696 namespace: update event counter when umounting a deleted dentry
commit e06b933e6ded42384164d28a2060b7f89243b895 upstream.

- m_start() in fs/namespace.c expects that ns->event is incremented each
  time a mount added or removed from ns->list.
- umount_tree() removes items from the list but does not increment event
  counter, expecting that it's done before the function is called.
- There are some codepaths that call umount_tree() without updating
  "event" counter. e.g. from __detach_mounts().
- When this happens m_start may reuse a cached mount structure that no
  longer belongs to ns->list (i.e. use after free which usually leads
  to infinite loop).

This change fixes the above problem by incrementing global event counter
before invoking umount_tree().

Change-Id: I622c8e84dcb9fb63542372c5dbf0178ee86bb589
Signed-off-by: Andrey Ulanov <andreyu@google.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-08-10 11:49:27 +02:00
Eric W. Biederman
a400a79321 mnt: If fs_fully_visible fails call put_filesystem.
commit 97c1df3e54e811aed484a036a798b4b25d002ecf upstream.

Add this trivial missing error handling.

Fixes: 1b852bceb0 ("mnt: Refactor the logic for mounting sysfs and proc in a user namespace")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-07-27 09:47:28 -07:00
Eric W. Biederman
6256d2f541 mnt: Account for MS_RDONLY in fs_fully_visible
commit 695e9df010e40f407f4830dc11d53dce957710ba upstream.

In rare cases it is possible for s_flags & MS_RDONLY to be set but
MNT_READONLY to be clear.  This starting combination can cause
fs_fully_visible to fail to ensure that the new mount is readonly.
Therefore force MNT_LOCK_READONLY in the new mount if MS_RDONLY
is set on the source filesystem of the mount.

In general both MS_RDONLY and MNT_READONLY are set at the same for
mounts so I don't expect any programs to care.  Nor do I expect
MS_RDONLY to be set on proc or sysfs in the initial user namespace,
which further decreases the likelyhood of problems.

Which means this change should only affect system configurations by
paranoid sysadmins who should welcome the additional protection
as it keeps people from wriggling out of their policies.

Fixes: 8c6cf9cc82 ("mnt: Modify fs_fully_visible to deal with locked ro nodev and atime")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-07-27 09:47:28 -07:00
Eric W. Biederman
57eb6e3dbd mnt: fs_fully_visible test the proper mount for MNT_LOCKED
commit d71ed6c930ac7d8f88f3cef6624a7e826392d61f upstream.

MNT_LOCKED implies on a child mount implies the child is locked to the
parent.  So while looping through the children the children should be
tested (not their parent).

Typically an unshare of a mount namespace locks all mounts together
making both the parent and the slave as locked but there are a few
corner cases where other things work.

Fixes: ceeb0e5d39 ("vfs: Ignore unlocked mounts in fs_fully_visible")
Reported-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-07-27 09:47:28 -07:00
Linus Torvalds
73b6fa8e49 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull user namespace updates from Eric Biederman:
 "This finishes up the changes to ensure proc and sysfs do not start
  implementing executable files, as the there are application today that
  are only secure because such files do not exist.

  It akso fixes a long standing misfeature of /proc/<pid>/mountinfo that
  did not show the proper source for files bind mounted from
  /proc/<pid>/ns/*.

  It also straightens out the handling of clone flags related to user
  namespaces, fixing an unnecessary failure of unshare(CLONE_NEWUSER)
  when files such as /proc/<pid>/environ are read while <pid> is calling
  unshare.  This winds up fixing a minor bug in unshare flag handling
  that dates back to the first version of unshare in the kernel.

  Finally, this fixes a minor regression caused by the introduction of
  sysfs_create_mount_point, which broke someone's in house application,
  by restoring the size of /sys/fs/cgroup to 0 bytes.  Apparently that
  application uses the directory size to determine if a tmpfs is mounted
  on /sys/fs/cgroup.

  The bind mount escape fixes are present in Al Viros for-next branch.
  and I expect them to come from there.  The bind mount escape is the
  last of the user namespace related security bugs that I am aware of"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
  fs: Set the size of empty dirs to 0.
  userns,pidns: Force thread group sharing, not signal handler sharing.
  unshare: Unsharing a thread does not require unsharing a vm
  nsfs: Add a show_path method to fix mountinfo
  mnt: fs_fully_visible enforce noexec and nosuid  if !SB_I_NOEXEC
  vfs: Commit to never having exectuables on proc and sysfs.
2015-09-01 16:13:25 -07:00
Eric W. Biederman
fe78fcc85a mnt: In detach_mounts detach the appropriate unmounted mount
The handling of in detach_mounts of unmounted but connected mounts is
buggy and can lead to an infinite loop.

Correct the handling of unmounted mounts in detach_mount.  When the
mountpoint of an unmounted but connected mount is connected to a
dentry, and that dentry is deleted we need to disconnect that mount
from the parent mount and the deleted dentry.

Nothing changes for the unmounted and connected children.  They can be
safely ignored.

Cc: stable@vger.kernel.org
Fixes: ce07d891a0 mnt: Honor MNT_LOCKED when detaching mounts
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2015-07-23 11:31:15 -05:00
Eric W. Biederman
f2d0a123bc mnt: Clarify and correct the disconnect logic in umount_tree
rmdir mntpoint will result in an infinite loop when there is
a mount locked on the mountpoint in another mount namespace.

This is because the logic to test to see if a mount should
be disconnected in umount_tree is buggy.

Move the logic to decide if a mount should remain connected to
it's mountpoint into it's own function disconnect_mount so that
clarity of expression instead of terseness of expression becomes
a virtue.

When the conditions where it is invalid to leave a mount connected
are first ruled out, the logic for deciding if a mount should
be disconnected becomes much clearer and simpler.

Fixes: e0c9c0afd2 mnt: Update detach_mounts to leave mounts connected
Fixes: ce07d891a0 mnt: Honor MNT_LOCKED when detaching mounts
Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2015-07-22 20:33:27 -05:00
Eric W. Biederman
77b1a97d21 mnt: fs_fully_visible enforce noexec and nosuid if !SB_I_NOEXEC
The filesystems proc and sysfs do not have executable files do not
have exectuable files today and portions of userspace break if we do
enforce nosuid and noexec consistency of nosuid and noexec flags
between previous mounts and new mounts of proc and sysfs.

Add the code to enforce consistency of the nosuid and noexec flags,
and use the presence of SB_I_NOEXEC to signal that there is no need to
bother.

This results in a completely userspace invisible change that makes it
clear fs_fully_visible can only skip the enforcement of noexec and
nosuid because it is known the filesystems in question do not support
executables.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2015-07-10 10:41:13 -05:00
Linus Torvalds
0cbee99269 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull user namespace updates from Eric Biederman:
 "Long ago and far away when user namespaces where young it was realized
  that allowing fresh mounts of proc and sysfs with only user namespace
  permissions could violate the basic rule that only root gets to decide
  if proc or sysfs should be mounted at all.

  Some hacks were put in place to reduce the worst of the damage could
  be done, and the common sense rule was adopted that fresh mounts of
  proc and sysfs should allow no more than bind mounts of proc and
  sysfs.  Unfortunately that rule has not been fully enforced.

  There are two kinds of gaps in that enforcement.  Only filesystems
  mounted on empty directories of proc and sysfs should be ignored but
  the test for empty directories was insufficient.  So in my tree
  directories on proc, sysctl and sysfs that will always be empty are
  created specially.  Every other technique is imperfect as an ordinary
  directory can have entries added even after a readdir returns and
  shows that the directory is empty.  Special creation of directories
  for mount points makes the code in the kernel a smidge clearer about
  it's purpose.  I asked container developers from the various container
  projects to help test this and no holes were found in the set of mount
  points on proc and sysfs that are created specially.

  This set of changes also starts enforcing the mount flags of fresh
  mounts of proc and sysfs are consistent with the existing mount of
  proc and sysfs.  I expected this to be the boring part of the work but
  unfortunately unprivileged userspace winds up mounting fresh copies of
  proc and sysfs with noexec and nosuid clear when root set those flags
  on the previous mount of proc and sysfs.  So for now only the atime,
  read-only and nodev attributes which userspace happens to keep
  consistent are enforced.  Dealing with the noexec and nosuid
  attributes remains for another time.

  This set of changes also addresses an issue with how open file
  descriptors from /proc/<pid>/ns/* are displayed.  Recently readlink of
  /proc/<pid>/fd has been triggering a WARN_ON that has not been
  meaningful since it was added (as all of the code in the kernel was
  converted) and is not now actively wrong.

  There is also a short list of issues that have not been fixed yet that
  I will mention briefly.

  It is possible to rename a directory from below to above a bind mount.
  At which point any directory pointers below the renamed directory can
  be walked up to the root directory of the filesystem.  With user
  namespaces enabled a bind mount of the bind mount can be created
  allowing the user to pick a directory whose children they can rename
  to outside of the bind mount.  This is challenging to fix and doubly
  so because all obvious solutions must touch code that is in the
  performance part of pathname resolution.

  As mentioned above there is also a question of how to ensure that
  developers by accident or with purpose do not introduce exectuable
  files on sysfs and proc and in doing so introduce security regressions
  in the current userspace that will not be immediately obvious and as
  such are likely to require breaking userspace in painful ways once
  they are recognized"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
  vfs: Remove incorrect debugging WARN in prepend_path
  mnt: Update fs_fully_visible to test for permanently empty directories
  sysfs: Create mountpoints with sysfs_create_mount_point
  sysfs: Add support for permanently empty directories to serve as mount points.
  kernfs: Add support for always empty directories.
  proc: Allow creating permanently empty directories that serve as mount points
  sysctl: Allow creating permanently empty directories that serve as mountpoints.
  fs: Add helper functions for permanently empty directories.
  vfs: Ignore unlocked mounts in fs_fully_visible
  mnt: Modify fs_fully_visible to deal with locked ro nodev and atime
  mnt: Refactor the logic for mounting sysfs and proc in a user namespace
2015-07-03 15:20:57 -07:00
Eric W. Biederman
7236c85e1b mnt: Update fs_fully_visible to test for permanently empty directories
fs_fully_visible attempts to make fresh mounts of proc and sysfs give
the mounter no more access to proc and sysfs than if they could have
by creating a bind mount.  One aspect of proc and sysfs that makes
this particularly tricky is that there are other filesystems that
typically mount on top of proc and sysfs.  As those filesystems are
mounted on empty directories in practice it is safe to ignore them.
However testing to ensure filesystems are mounted on empty directories
has not been something the in kernel data structures have supported so
the current test for an empty directory which checks to see
if nlink <= 2 is a bit lacking.

proc and sysfs have recently been modified to use the new empty_dir
infrastructure to create all of their dedicated mount points.  Instead
of testing for S_ISDIR(inode->i_mode) && i_nlink <= 2 to see if a
directory is empty, test for is_empty_dir_inode(inode).  That small
change guaranteess mounts found on proc and sysfs really are safe to
ignore, because the directories are not only empty but nothing can
ever be added to them.  This guarantees there is nothing to worry
about when mounting proc and sysfs.

Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2015-07-01 10:36:49 -05:00
Eric W. Biederman
ceeb0e5d39 vfs: Ignore unlocked mounts in fs_fully_visible
Limit the mounts fs_fully_visible considers to locked mounts.
Unlocked can always be unmounted so considering them adds hassle
but no security benefit.

Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2015-07-01 10:36:35 -05:00
Yann Droneaud
ede1bf0dcf fs: use seq_open_private() for proc_mounts
A patchset to remove support for passing pre-allocated struct seq_file to
seq_open().  Such feature is undocumented and prone to error.

In particular, if seq_release() is used in release handler, it will
kfree() a pointer which was not allocated by seq_open().

So this patchset drops support for pre-allocated struct seq_file: it's
only of use in proc_namespace.c and can be easily replaced by using
seq_open_private()/seq_release_private().

Additionally, it documents the use of file->private_data to hold pointer
to struct seq_file by seq_open().

This patch (of 3):

Since patch described below, from v2.6.15-rc1, seq_open() could use a
struct seq_file already allocated by the caller if the pointer to the
structure is stored in file->private_data before calling the function.

    Commit 1abe77b0fc
    Author: Al Viro <viro@zeniv.linux.org.uk>
    Date:   Mon Nov 7 17:15:34 2005 -0500

        [PATCH] allow callers of seq_open do allocation themselves

        Allow caller of seq_open() to kmalloc() seq_file + whatever else they
        want and set ->private_data to it.  seq_open() will then abstain from
        doing allocation itself.

Such behavior is only used by mounts_open_common().

In order to drop support for such uncommon feature, proc_mounts is
converted to use seq_open_private(), which take care of allocating the
proc_mounts structure, making it available through ->private in struct
seq_file.

Conversely, proc_mounts is converted to use seq_release_private(), in
order to release the private structure allocated by seq_open_private().

Then, ->private is used directly instead of proc_mounts() macro to access
to the proc_mounts structure.

Link: http://lkml.kernel.org/r/cover.1433193673.git.ydroneaud@opteya.com
Signed-off-by: Yann Droneaud <ydroneaud@opteya.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-30 19:44:56 -07:00
Eric W. Biederman
8c6cf9cc82 mnt: Modify fs_fully_visible to deal with locked ro nodev and atime
Ignore an existing mount if the locked readonly, nodev or atime
attributes are less permissive than the desired attributes
of the new mount.

On success ensure the new mount locks all of the same readonly, nodev and
atime attributes as the old mount.

The nosuid and noexec attributes are not checked here as this change
is destined for stable and enforcing those attributes causes a
regression in lxc and libvirt-lxc where those applications will not
start and there are no known executables on sysfs or proc and no known
way to create exectuables without code modifications

Cc: stable@vger.kernel.org
Fixes: e51db73532 ("userns: Better restrictions on when proc and sysfs can be mounted")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2015-06-04 10:29:25 -05:00
Eric W. Biederman
1b852bceb0 mnt: Refactor the logic for mounting sysfs and proc in a user namespace
Fresh mounts of proc and sysfs are a very special case that works very
much like a bind mount.  Unfortunately the current structure can not
preserve the MNT_LOCK... mount flags.  Therefore refactor the logic
into a form that can be modified to preserve those lock bits.

Add a new filesystem flag FS_USERNS_VISIBLE that requires some mount
of the filesystem be fully visible in the current mount namespace,
before the filesystem may be mounted.

Move the logic for calling fs_fully_visible from proc and sysfs into
fs/namespace.c where it has greater access to mount namespace state.

Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2015-05-13 21:44:11 -05:00
Al Viro
294d71ff2f new helper: __legitimize_mnt()
same as legitimize_mnt(), except that it does *not* drop and regain
rcu_read_lock; return values are
0  =>  grabbed a reference, we are fine
1  =>  failed, just go away
-1 =>  failed, go away and mntput(bastard) when outside of rcu_read_lock

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-11 08:13:14 -04:00
Eric W. Biederman
7e96c1b0e0 mnt: Fix fs_fully_visible to verify the root directory is visible
This fixes a dumb bug in fs_fully_visible that allows proc or sys to
be mounted if there is a bind mount of part of /proc/ or /sys/ visible.

Cc: stable@vger.kernel.org
Reported-by: Eric Windisch <ewindisch@docker.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2015-05-09 11:55:50 -05:00
Eric W. Biederman
e0c9c0afd2 mnt: Update detach_mounts to leave mounts connected
Now that it is possible to lazily unmount an entire mount tree and
leave the individual mounts connected to each other add a new flag
UMOUNT_CONNECTED to umount_tree to force this behavior and use
this flag in detach_mounts.

This closes a bug where the deletion of a file or directory could
trigger an unmount and reveal data under a mount point.

Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2015-04-09 11:39:57 -05:00
Eric W. Biederman
f53e579751 mnt: Fix the error check in __detach_mounts
lookup_mountpoint can return either NULL or an error value.
Update the test in __detach_mounts to test for an error value
to avoid pathological cases causing a NULL pointer dereferences.

The callers of __detach_mounts should prevent it from ever being
called on an unlinked dentry but don't take any chances.

Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2015-04-09 11:39:56 -05:00
Eric W. Biederman
ce07d891a0 mnt: Honor MNT_LOCKED when detaching mounts
Modify umount(MNT_DETACH) to keep mounts in the hash table that are
locked to their parent mounts, when the parent is lazily unmounted.

In mntput_no_expire detach the children from the hash table, depending
on mnt_pin_kill in cleanup_mnt to decrement the mnt_count of the children.

In __detach_mounts if there are any mounts that have been unmounted
but still are on the list of mounts of a mountpoint, remove their
children from the mount hash table and those children to the unmounted
list so they won't linger potentially indefinitely waiting for their
final mntput, now that the mounts serve no purpose.

Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2015-04-09 11:39:55 -05:00
Eric W. Biederman
6a46c5735c mnt: Factor umount_mnt from umount_tree
For future use factor out a function umount_mnt from umount_tree.
This function unhashes a mount and remembers where the mount
was mounted so that eventually when the code makes it to a
sleeping context the mountpoint can be dput.

Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2015-04-09 11:39:54 -05:00
Eric W. Biederman
7bdb11de8e mnt: Factor out unhash_mnt from detach_mnt and umount_tree
Create a function unhash_mnt that contains the common code between
detach_mnt and umount_tree, and use unhash_mnt in place of the common
code.  This add a unncessary list_del_init(mnt->mnt_child) into
umount_tree but given that mnt_child is already empty this extra
line is a noop.

Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2015-04-09 11:39:54 -05:00
Eric W. Biederman
cd4a40174b mnt: Fail collect_mounts when applied to unmounted mounts
The only users of collect_mounts are in audit_tree.c

In audit_trim_trees and audit_add_tree_rule the path passed into
collect_mounts is generated from kern_path passed an audit_tree
pathname which is guaranteed to be an absolute path.   In those cases
collect_mounts is obviously intended to work on mounted paths and
if a race results in paths that are unmounted when collect_mounts
it is reasonable to fail early.

The paths passed into audit_tag_tree don't have the absolute path
check.  But are used to play with fsnotify and otherwise interact with
the audit_trees, so again operating only on mounted paths appears
reasonable.

Avoid having to worry about what happens when we try and audit
unmounted filesystems by restricting collect_mounts to mounts
that appear in the mount tree.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2015-04-09 11:38:31 -05:00
Eric W. Biederman
5d88457eb5 mnt: On an unmount propagate clearing of MNT_LOCKED
A prerequisite of calling umount_tree is that the point where the tree
is mounted at is valid to unmount.

If we are propagating the effect of the unmount clear MNT_LOCKED in
every instance where the same filesystem is mounted on the same
mountpoint in the mount tree, as we know (by virtue of the fact
that umount_tree was called) that it is safe to reveal what
is at that mountpoint.

Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2015-04-02 20:34:19 -05:00
Eric W. Biederman
411a938b5a mnt: Delay removal from the mount hash.
- Modify __lookup_mnt_hash_last to ignore mounts that have MNT_UMOUNTED set.
- Don't remove mounts from the mount hash table in propogate_umount
- Don't remove mounts from the mount hash table in umount_tree before
  the entire list of mounts to be umounted is selected.
- Remove mounts from the mount hash table as the last thing that
  happens in the case where a mount has a parent in umount_tree.
  Mounts without parents are not hashed (by definition).

This paves the way for delaying removal from the mount hash table even
farther and fixing the MNT_LOCKED vs MNT_DETACH issue.

Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2015-04-02 20:34:19 -05:00
Eric W. Biederman
590ce4bcbf mnt: Add MNT_UMOUNT flag
In some instances it is necessary to know if the the unmounting
process has begun on a mount.  Add MNT_UMOUNT to make that reliably
testable.

This fix gets used in fixing locked mounts in MNT_DETACH

Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2015-04-02 20:34:18 -05:00
Eric W. Biederman
c003b26ff9 mnt: In umount_tree reuse mnt_list instead of mnt_hash
umount_tree builds a list of mounts that need to be unmounted.
Utilize mnt_list for this purpose instead of mnt_hash.  This begins to
allow keeping a mount on the mnt_hash after it is unmounted, which is
necessary for a properly functioning MNT_LOCKED implementation.

The fact that mnt_list is an ordinary list makding available list_move
is nice bonus.

Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2015-04-02 20:34:18 -05:00
Eric W. Biederman
8318e667f1 mnt: Don't propagate umounts in __detach_mounts
Invoking mount propagation from __detach_mounts is inefficient and
wrong.

It is inefficient because __detach_mounts already walks the list of
mounts that where something needs to be done, and mount propagation
walks some subset of those mounts again.

It is actively wrong because if the dentry that is passed to
__detach_mounts is not part of the path to a mount that mount should
not be affected.

change_mnt_propagation(p,MS_PRIVATE) modifies the mount propagation
tree of a master mount so it's slaves are connected to another master
if possible.  Which means even removing a mount from the middle of a
mount tree with __detach_mounts will not deprive any mount propagated
mount events.

Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2015-04-02 20:34:17 -05:00
Eric W. Biederman
e819f15210 mnt: Improve the umount_tree flags
- Remove the unneeded declaration from pnode.h
- Mark umount_tree static as it has no callers outside of namespace.c
- Define an enumeration of umount_tree's flags.
- Pass umount_tree's flags in by name

This removes the magic numbers 0, 1 and 2 making the code a little
clearer and makes it possible for there to be lazy unmounts that don't
propagate.  Which is what __detach_mounts actually wants for example.

Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2015-04-02 20:34:17 -05:00