This replaces all code in fs/compat_ioctl.c that translated
ioctl arguments into a in-kernel structure, then performed
do_ioctl under set_fs(KERNEL_DS), with code that allocates
data on the user stack and can call the VFS ioctl handler
under USER_DS.

This is done as a hardening measure because the caller
does not know what kind of ioctl handler will be invoked,
only that no corresponding compat_ioctl handler exists and
what the ioctl command number is. The accidental
invocation of an unlocked_ioctl handler that unexpectedly
calls copy_to_user could be a severe security issue.
Signed-off-by: Jann Horn <jann@thejh.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

In code in fs/compat_ioctl.c that translates ioctl arguments
into a in-kernel structure, then performs sys_ioctl, possibly
under set_fs(KERNEL_DS), this commit changes the sys_ioctl
calls to do_ioctl calls. do_ioctl is a new function that does
the same thing as sys_ioctl, but doesn't look up the fd again.

This change is made to avoid (potential) security issues
because of ioctl handlers that accept one of the ioctl
commands I2C_FUNCS, VIDEO_GET_EVENT, MTIOCPOS, MTIOCGET,
TIOCGSERIAL, TIOCSSERIAL, RTC_IRQP_READ, RTC_EPOCH_READ.
This can happen for multiple reasons:

 - The ioctl command number could be reused.
 - The ioctl handler might not check the full ioctl
   command. This is e.g. true for drm_ioctl.
 - The ioctl handler is very special, e.g. cuse_file_ioctl

The real issue is that set_fs(KERNEL_DS) is used here,
but that's fixed in a separate commit
"compat_ioctl: don't call do_ioctl under set_fs(KERNEL_DS)".

This change mitigates potential security issues by
preventing a race that permits invocation of
unlocked_ioctl handlers under KERNEL_DS through compat
code even if a corresponding compat_ioctl handler exists.

So far, no way has been identified to use this to damage
kernel memory without having CAP_SYS_ADMIN in the init ns
(with the capability, doing reads/writes at arbitrary
kernel addresses should be easy through CUSE's ioctl
handler with FUSE_IOCTL_UNRESTRICTED set).

[AV: two missed sys_ioctl() taken care of]
Signed-off-by: Jann Horn <jann@thejh.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

This allow to directly print block_device name.
Currently one should use bdevname() with temporal char buffer.
This is very ineffective because bloat stack usage for deep IO call-traces

Example:
	%pg  ->    sda, sda1 or loop0p1

[AV: fixed a minor braino - position updates should not be dependent
upon having reached the of buffer]
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

gendisk with part==0 is obviously gendisk->disk_name.
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Number of fds is already known based on passed list.

No functional changes.
Signed-off-by: Mateusz Guzik <mguzik@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

[folded a fix by Dan Carpenter]
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

... rather than play with __get_free_pages() (and figuring out the
allocation order, etc.)
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

get_zeroed_page does alloc_page and returns page_address of the result;
subsequent virt_to_page will recover the page, but since the caller
needs both page and its page_address() anyway, why bother going through
that wrapper at all?
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

... so virt_to_phys(p) & (PAGE_SIZE - 1) is a very odd way to
spell offset_in_page(p).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

let it just return NULL, pointer to kernel copy or ERR_PTR().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

When __get_user64() had been removed, its helper (__get_user64_nocheck)
got missed.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

they hadn't been used in last 15 years...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

all we do to buffer is strncmp()...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

again, it only parses the contents of the copied buffer, so
get_zeroed_page() might as well had been kmalloc(), which makes
it open-coded memdup_user_nul()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Nothing in there gives a damn about the buffer alignment - it
just parses its contents.  So the use of get_zeroed_page()
doesn't buy us anything - might as well had been kmalloc(),
which makes that code equivalent to open-coded memdup_user_nul()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

A _lot_ of ->write() instances were open-coding it; some are
converted to memdup_user_nul(), a lot more remain...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Similar to memdup_user(), except that allocated buffer is one byte
longer and '\0' is stored after the copied data.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Pull MIPS build fix from Ralf Baechle:
 "Fix a makefile issue resulting in build breakage with older binutils.

  This has sat in -next for a few days, testers and buildbot are happy
  with it, too though if you are going for another -rc that'd certainly
  help ironing out a few more issues"

* 'upstream' of git://git.linux-mips.org/pub/scm/ralf/upstream-linus:
  MIPS: VDSO: Fix build error with binutils 2.24 and earlier

Pull i915 drm fixes from Jani Nikula:
 "Two display fixes still for v4.4.

  The new year's resolution is to start using signed tags per Linus'
  request.  This one is still unsigned; I want to fix this up in our
  maintainer scripts instead of doing it one-off"

* tag 'drm-intel-fixes-2016-01-02' of git://anongit.freedesktop.org/drm-intel:
  drm/i915: increase the tries for HDMI hotplug live status checking
  drm/i915: Unbreak check_digital_port_conflicts()

Pull PCI bugfix from Bjorn Helgaas:
 "Here's another fix for v4.4.

  This fixes 32-bit config reads for the HiSilicon driver.  Obviously
  the driver is completely broken without this fix (apparently it
  actually was tested internally, but got broken somehow in the process
  of upstreaming it).

  Summary:

  HiSilicon host bridge driver
    Fix 32-bit config reads (Dongdong Liu)"

* tag 'pci-v4.4-fixes-3' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci:
  PCI: hisi: Fix hisi_pcie_cfg_read() 32-bit reads

Pull sparc fixes from David Miller:
 "Just some missing syscall wire ups"

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc:
  sparc: Wire up mlock2 system call.
  sparc: Add all necessary direct socket system calls.

Pull networking fixes from David Miller:

 1) Prevent XFRM per-cpu counter updates for one namespace from being
    applied to another namespace.  Fix from DanS treetman.

 2) Fix RCU de-reference in iwl_mvm_get_key_sta_id(), from Johannes
    Berg.

 3) Remove ethernet header assumption in nft_do_chain_netdev(), from
    Pablo Neira Ayuso.

 4) Fix cpsw PHY ident with multiple slaves and fixed-phy, from Pascal
    Speck.

 5) Fix use after free in sixpack_close and mkiss_close.

 6) Fix VXLAN fw assertion on bnx2x, from Yuval Mintz.

 7) natsemi doesn't check for DMA mapping errors, from Alexey
    Khoroshilov.

 8) Fix inverted test in ip6addrlbl_get(), from ANdrey Ryabinin.

 9) Missing initialization of needed_headroom in geneve tunnel driver,
    from Paolo Abeni.

10) Fix conntrack template leak in openvswitch, from Joe Stringer.

11) Mission initialization of wq->flags in sock_alloc_inode(), from
    Nicolai Stange.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (35 commits)
  sctp: sctp should release assoc when sctp_make_abort_user return NULL in sctp_close
  net, socket, socket_wq: fix missing initialization of flags
  drivers: net: cpsw: fix error return code
  openvswitch: Fix template leak in error cases.
  sctp: label accepted/peeled off sockets
  sctp: use GFP_USER for user-controlled kmalloc
  qlcnic: fix a loop exit condition better
  net: cdc_ncm: avoid changing RX/TX buffers on MTU changes
  geneve: initialize needed_headroom
  ipv6: honor ifindex in case we receive ll addresses in router advertisements
  addrconf: always initialize sysctl table data
  ipv6/addrlabel: fix ip6addrlbl_get()
  switchdev: bridge: Pass ageing time as clock_t instead of jiffies
  sh_eth: fix 16-bit descriptor field access endianness too
  veth: don’t modify ip_summed; doing so treats packets with bad checksums as good.
  net: usb: cdc_ncm: Adding Dell DW5813 LTE AT&T Mobile Broadband Card
  net: usb: cdc_ncm: Adding Dell DW5812 LTE Verizon Mobile Broadband Card
  natsemi: add checks for dma mapping errors
  rhashtable: Kill harmless RCU warning in rhashtable_walk_init
  openvswitch: correct encoding of set tunnel action attributes
  ...