<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux/arch/alpha/kernel, branch v5.7</title>
<subtitle>Mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
</subtitle>
<id>https://git.shady.money/linux/atom?h=v5.7</id>
<link rel='self' href='https://git.shady.money/linux/atom?h=v5.7'/>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/'/>
<updated>2020-04-07T17:43:42Z</updated>
<entry>
<title>asm-generic: fix unistd_32.h generation format</title>
<updated>2020-04-07T17:43:42Z</updated>
<author>
<name>Michal Simek</name>
<email>michal.simek@xilinx.com</email>
</author>
<published>2020-04-07T03:09:23Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=06e85c7e9a1c1356038936566fc23f7c0d363b96'/>
<id>urn:sha1:06e85c7e9a1c1356038936566fc23f7c0d363b96</id>
<content type='text'>
Generated files are also checked by sparse that's why add newline to
remove sparse (C=1) warning.

The issue was found on Microblaze and reported like this:
./arch/microblaze/include/generated/uapi/asm/unistd_32.h:438:45: warning:
no newline at end of file

Mips and PowerPC have it already but let's align with style used by m68k.

Signed-off-by: Michal Simek &lt;michal.simek@xilinx.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Reviewed-by: Stefan Asserhall &lt;stefan.asserhall@xilinx.com&gt;
Acked-by: Max Filippov &lt;jcmvbkbc@gmail.com&gt; (xtensa)
Cc: Arnd Bergmann &lt;arnd@arndb.de&gt;
Cc: Max Filippov &lt;jcmvbkbc@gmail.com&gt;
Cc: Benjamin Herrenschmidt &lt;benh@kernel.crashing.org&gt;
Cc: Chris Zankel &lt;chris@zankel.net&gt;
Cc: David S. Miller &lt;davem@davemloft.net&gt;
Cc: Fenghua Yu &lt;fenghua.yu@intel.com&gt;
Cc: Helge Deller &lt;deller@gmx.de&gt;
Cc: Ivan Kokshaysky &lt;ink@jurassic.park.msu.ru&gt;
Cc: James Bottomley &lt;James.Bottomley@HansenPartnership.com&gt;
Cc: Matt Turner &lt;mattst88@gmail.com&gt;
Cc: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Cc: Paul Burton &lt;paulburton@kernel.org&gt;
Cc: Paul Mackerras &lt;paulus@samba.org&gt;
Cc: Ralf Baechle &lt;ralf@linux-mips.org&gt;
Cc: Rich Felker &lt;dalias@libc.org&gt;
Cc: Richard Henderson &lt;rth@twiddle.net&gt;
Cc: Tony Luck &lt;tony.luck@intel.com&gt;
Cc: Yoshinori Sato &lt;ysato@users.sourceforge.jp&gt;
Link: http://lkml.kernel.org/r/4d32ab4e1fb2edb691d2e1687e8fb303c09fd023.1581504803.git.michal.simek@xilinx.com
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>Merge tag 'pci-v5.7-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci</title>
<updated>2020-04-03T21:25:02Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2020-04-03T21:25:02Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=86f26a77cb0cf532a92be18d2c065f5158e1a545'/>
<id>urn:sha1:86f26a77cb0cf532a92be18d2c065f5158e1a545</id>
<content type='text'>
Pull pci updates from Bjorn Helgaas:
 "Enumeration:

   - Revert sysfs "rescan" renames that broke apps (Kelsey Skunberg)

   - Add more 32 GT/s link speed decoding and improve the implementation
     (Yicong Yang)

  Resource management:

   - Add support for sizing programmable host bridge apertures and fix a
     related alpha Nautilus regression (Ivan Kokshaysky)

  Interrupts:

   - Add boot interrupt quirk mechanism for Xeon chipsets and document
     boot interrupts (Sean V Kelley)

  PCIe native device hotplug:

   - When possible, disable in-band presence detect and use PDS
     (Alexandru Gagniuc)

   - Add DMI table for devices that don't use in-band presence detection
     but don't advertise that correctly (Stuart Hayes)

   - Fix hang when powering slots up/down via sysfs (Lukas Wunner)

   - Fix an MSI interrupt race (Stuart Hayes)

  Virtualization:

   - Add ACS quirks for Zhaoxin devices (Raymond Pang)

  Error handling:

   - Add Error Disconnect Recover (EDR) support so firmware can report
     devices disconnected via DPC and we can try to recover (Kuppuswamy
     Sathyanarayanan)

  Peer-to-peer DMA:

   - Add Intel Sky Lake-E Root Ports B, C, D to the whitelist (Andrew
     Maier)

  ASPM:

   - Reduce severity of common clock config message (Chris Packham)

   - Clear the correct bits when enabling L1 substates, so we don't go
     to the wrong state (Yicong Yang)

  Endpoint framework:

   - Replace EPF linkup ops with notifier call chain and improve locking
     (Kishon Vijay Abraham I)

   - Fix concurrent memory allocation in OB address region (Kishon Vijay
     Abraham I)

   - Move PF function number assignment to EPC core to support multiple
     function creation methods (Kishon Vijay Abraham I)

   - Fix issue with clearing configfs "start" entry (Kunihiko Hayashi)

   - Fix issue with endpoint MSI-X ignoring BAR Indicator and Table
     Offset (Kishon Vijay Abraham I)

   - Add support for testing DMA transfers (Kishon Vijay Abraham I)

   - Add support for testing &gt; 10 endpoint devices (Kishon Vijay Abraham I)

   - Add support for tests to clear IRQ (Kishon Vijay Abraham I)

   - Add common DT schema for endpoint controllers (Kishon Vijay Abraham I)

  Amlogic Meson PCIe controller driver:

   - Add DT bindings for AXG PCIe PHY, shared MIPI/PCIe analog PHY (Remi
     Pommarel)

   - Add Amlogic AXG PCIe PHY, AXG MIPI/PCIe analog PHY drivers (Remi
     Pommarel)

  Cadence PCIe controller driver:

   - Add Root Complex/Endpoint DT schema for Cadence PCIe (Kishon Vijay
     Abraham I)

  Intel VMD host bridge driver:

   - Add two VMD Device IDs that require bus restriction mode (Sushma
     Kalakota)

  Mobiveil PCIe controller driver:

   - Refactor and modularize mobiveil driver (Hou Zhiqiang)

   - Add support for Mobiveil GPEX Gen4 host (Hou Zhiqiang)

  Microsoft Hyper-V host bridge driver:

   - Add support for Hyper-V PCI protocol version 1.3 and
     PCI_BUS_RELATIONS2 (Long Li)

   - Refactor to prepare for virtual PCI on non-x86 architectures (Boqun
     Feng)

   - Fix memory leak in hv_pci_probe()'s error path (Dexuan Cui)

  NVIDIA Tegra PCIe controller driver:

   - Use pci_parse_request_of_pci_ranges() (Rob Herring)

   - Add support for endpoint mode and related DT updates (Vidya Sagar)

   - Reduce -EPROBE_DEFER error message log level (Thierry Reding)

  Qualcomm PCIe controller driver:

   - Restrict class fixup to specific Qualcomm devices (Bjorn Andersson)

  Synopsys DesignWare PCIe controller driver:

   - Refactor core initialization code for endpoint mode (Vidya Sagar)

   - Fix endpoint MSI-X to use correct table address (Kishon Vijay
     Abraham I)

  TI DRA7xx PCIe controller driver:

   - Fix MSI IRQ handling (Vignesh Raghavendra)

  TI Keystone PCIe controller driver:

   - Allow AM654 endpoint to raise MSI-X interrupt (Kishon Vijay Abraham I)

  Miscellaneous:

   - Quirk ASMedia XHCI USB to avoid "PME# from D0" defect (Kai-Heng
     Feng)

   - Use ioremap(), not phys_to_virt(), for platform ROM to fix video
     ROM mapping with CONFIG_HIGHMEM (Mikel Rychliski)"

* tag 'pci-v5.7-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci: (96 commits)
  misc: pci_endpoint_test: remove duplicate macro PCI_ENDPOINT_TEST_STATUS
  PCI: tegra: Print -EPROBE_DEFER error message at debug level
  misc: pci_endpoint_test: Use full pci-endpoint-test name in request_irq()
  misc: pci_endpoint_test: Fix to support &gt; 10 pci-endpoint-test devices
  tools: PCI: Add 'e' to clear IRQ
  misc: pci_endpoint_test: Add ioctl to clear IRQ
  misc: pci_endpoint_test: Avoid using module parameter to determine irqtype
  PCI: keystone: Allow AM654 PCIe Endpoint to raise MSI-X interrupt
  PCI: dwc: Fix dw_pcie_ep_raise_msix_irq() to get correct MSI-X table address
  PCI: endpoint: Fix -&gt;set_msix() to take BIR and offset as arguments
  misc: pci_endpoint_test: Add support to get DMA option from userspace
  tools: PCI: Add 'd' command line option to support DMA
  misc: pci_endpoint_test: Use streaming DMA APIs for buffer allocation
  PCI: endpoint: functions/pci-epf-test: Print throughput information
  PCI: endpoint: functions/pci-epf-test: Add DMA support to transfer data
  PCI: pciehp: Fix MSI interrupt race
  PCI: pciehp: Fix indefinite wait on sysfs requests
  PCI: endpoint: Fix clearing start entry in configfs
  PCI: tegra: Add support for PCIe endpoint mode in Tegra194
  PCI: sysfs: Revert "rescan" file renames
  ...
</content>
</entry>
<entry>
<title>Merge tag 'spdx-5.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/spdx</title>
<updated>2020-04-03T20:12:26Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2020-04-03T20:12:26Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=ff2ae607c6f329d11a3b0528801ea7474be8c3e9'/>
<id>urn:sha1:ff2ae607c6f329d11a3b0528801ea7474be8c3e9</id>
<content type='text'>
Pull SPDX updates from Greg KH:
 "Here are three SPDX patches for 5.7-rc1.

  One fixes up the SPDX tag for a single driver, while the other two go
  through the tree and add SPDX tags for all of the .gitignore files as
  needed.

  Nothing too complex, but you will get a merge conflict with your
  current tree, that should be trivial to handle (one file modified by
  two things, one file deleted.)

  All three of these have been in linux-next for a while, with no
  reported issues other than the merge conflict"

* tag 'spdx-5.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/spdx:
  ASoC: MT6660: make spdxcheck.py happy
  .gitignore: add SPDX License Identifier
  .gitignore: remove too obvious comments
</content>
</entry>
<entry>
<title>alpha: Fix nautilus PCI setup</title>
<updated>2020-03-30T14:52:35Z</updated>
<author>
<name>Ivan Kokshaysky</name>
<email>ink@jurassic.park.msu.ru</email>
</author>
<published>2020-03-18T00:50:29Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=5799dac9c38a9585bc021bcb965623b835f24b1f'/>
<id>urn:sha1:5799dac9c38a9585bc021bcb965623b835f24b1f</id>
<content type='text'>
Example (hopefully reasonable) of the new "size_windows" flag usage.

Fixes accidental breakage caused by f75b99d5a77d ("PCI: Enforce bus address
limits in resource allocation").

Fixes: f75b99d5a77d ("PCI: Enforce bus address limits in resource allocation")
Link: https://lore.kernel.org/r/20200318005029.GA8326@mail.rc.ru
Tested-by: Matt Turner &lt;mattst88@gmail.com&gt;
Signed-off-by: Ivan Kokshaysky &lt;ink@jurassic.park.msu.ru&gt;
Signed-off-by: Bjorn Helgaas &lt;bhelgaas@google.com&gt;
</content>
</entry>
<entry>
<title>alpha: Replace setup_irq() by request_irq()</title>
<updated>2020-03-29T19:03:41Z</updated>
<author>
<name>afzal mohammed</name>
<email>afzal.mohd.ma@gmail.com</email>
</author>
<published>2020-03-27T16:09:01Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=82c849eb36fe6dcfa955b25c7aad71b5c1b4403c'/>
<id>urn:sha1:82c849eb36fe6dcfa955b25c7aad71b5c1b4403c</id>
<content type='text'>
request_irq() is preferred over setup_irq(). Invocations of setup_irq()
occur after memory allocators are ready.

setup_irq() was required in older kernels as the memory allocator was not
available during early boot.

Hence replace setup_irq() by request_irq().

Signed-off-by: afzal mohammed &lt;afzal.mohd.ma@gmail.com&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Acked-by: Matt Turner &lt;mattst88@gmail.com&gt;
Link: https://lkml.kernel.org/r/51f8ae7da9f47a23596388141933efa2bdef317b.1585320721.git.afzal.mohd.ma@gmail.com

</content>
</entry>
<entry>
<title>.gitignore: add SPDX License Identifier</title>
<updated>2020-03-25T10:50:48Z</updated>
<author>
<name>Masahiro Yamada</name>
<email>masahiroy@kernel.org</email>
</author>
<published>2020-03-03T13:35:59Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=d198b34f3855eee2571dda03eea75a09c7c31480'/>
<id>urn:sha1:d198b34f3855eee2571dda03eea75a09c7c31480</id>
<content type='text'>
Add SPDX License Identifier to all .gitignore files.

Signed-off-by: Masahiro Yamada &lt;masahiroy@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>proc: convert everything to "struct proc_ops"</title>
<updated>2020-02-04T03:05:26Z</updated>
<author>
<name>Alexey Dobriyan</name>
<email>adobriyan@gmail.com</email>
</author>
<published>2020-02-04T01:37:17Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=97a32539b9568bb653683349e5a76d02ff3c3e2c'/>
<id>urn:sha1:97a32539b9568bb653683349e5a76d02ff3c3e2c</id>
<content type='text'>
The most notable change is DEFINE_SHOW_ATTRIBUTE macro split in
seq_file.h.

Conversion rule is:

	llseek		=&gt; proc_lseek
	unlocked_ioctl	=&gt; proc_ioctl

	xxx		=&gt; proc_xxx

	delete ".owner = THIS_MODULE" line

[akpm@linux-foundation.org: fix drivers/isdn/capi/kcapi_proc.c]
[sfr@canb.auug.org.au: fix kernel/sched/psi.c]
  Link: http://lkml.kernel.org/r/20200122180545.36222f50@canb.auug.org.au
Link: http://lkml.kernel.org/r/20191225172546.GB13378@avx2
Signed-off-by: Alexey Dobriyan &lt;adobriyan@gmail.com&gt;
Signed-off-by: Stephen Rothwell &lt;sfr@canb.auug.org.au&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>Merge tag 'threads-v5.6' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux</title>
<updated>2020-01-30T03:38:34Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2020-01-30T03:38:34Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=83fa805bcbfc53ae82eedd65132794ae324798e5'/>
<id>urn:sha1:83fa805bcbfc53ae82eedd65132794ae324798e5</id>
<content type='text'>
Pull thread management updates from Christian Brauner:
 "Sargun Dhillon over the last cycle has worked on the pidfd_getfd()
  syscall.

  This syscall allows for the retrieval of file descriptors of a process
  based on its pidfd. A task needs to have ptrace_may_access()
  permissions with PTRACE_MODE_ATTACH_REALCREDS (suggested by Oleg and
  Andy) on the target.

  One of the main use-cases is in combination with seccomp's user
  notification feature. As a reminder, seccomp's user notification
  feature was made available in v5.0. It allows a task to retrieve a
  file descriptor for its seccomp filter. The file descriptor is usually
  handed of to a more privileged supervising process. The supervisor can
  then listen for syscall events caught by the seccomp filter of the
  supervisee and perform actions in lieu of the supervisee, usually
  emulating syscalls. pidfd_getfd() is needed to expand its uses.

  There are currently two major users that wait on pidfd_getfd() and one
  future user:

   - Netflix, Sargun said, is working on a service mesh where users
     should be able to connect to a dns-based VIP. When a user connects
     to e.g. 1.2.3.4:80 that runs e.g. service "foo" they will be
     redirected to an envoy process. This service mesh uses seccomp user
     notifications and pidfd to intercept all connect calls and instead
     of connecting them to 1.2.3.4:80 connects them to e.g.
     127.0.0.1:8080.

   - LXD uses the seccomp notifier heavily to intercept and emulate
     mknod() and mount() syscalls for unprivileged containers/processes.
     With pidfd_getfd() more uses-cases e.g. bridging socket connections
     will be possible.

   - The patchset has also seen some interest from the browser corner.
     Right now, Firefox is using a SECCOMP_RET_TRAP sandbox managed by a
     broker process. In the future glibc will start blocking all signals
     during dlopen() rendering this type of sandbox impossible. Hence,
     in the future Firefox will switch to a seccomp-user-nofication
     based sandbox which also makes use of file descriptor retrieval.
     The thread for this can be found at
     https://sourceware.org/ml/libc-alpha/2019-12/msg00079.html

  With pidfd_getfd() it is e.g. possible to bridge socket connections
  for the supervisee (binding to a privileged port) and taking actions
  on file descriptors on behalf of the supervisee in general.

  Sargun's first version was using an ioctl on pidfds but various people
  pushed for it to be a proper syscall which he duely implemented as
  well over various review cycles. Selftests are of course included.
  I've also added instructions how to deal with merge conflicts below.

  There's also a small fix coming from the kernel mentee project to
  correctly annotate struct sighand_struct with __rcu to fix various
  sparse warnings. We've received a few more such fixes and even though
  they are mostly trivial I've decided to postpone them until after -rc1
  since they came in rather late and I don't want to risk introducing
  build warnings.

  Finally, there's a new prctl() command PR_{G,S}ET_IO_FLUSHER which is
  needed to avoid allocation recursions triggerable by storage drivers
  that have userspace parts that run in the IO path (e.g. dm-multipath,
  iscsi, etc). These allocation recursions deadlock the device.

  The new prctl() allows such privileged userspace components to avoid
  allocation recursions by setting the PF_MEMALLOC_NOIO and
  PF_LESS_THROTTLE flags. The patch carries the necessary acks from the
  relevant maintainers and is routed here as part of prctl()
  thread-management."

* tag 'threads-v5.6' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
  prctl: PR_{G,S}ET_IO_FLUSHER to support controlling memory reclaim
  sched.h: Annotate sighand_struct with __rcu
  test: Add test for pidfd getfd
  arch: wire up pidfd_getfd syscall
  pid: Implement pidfd_getfd syscall
  vfs, fdtable: Add fget_task helper
</content>
</entry>
<entry>
<title>Merge branch 'work.openat2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs</title>
<updated>2020-01-29T19:20:24Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2020-01-29T19:20:24Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=6aee4badd8126f3a2b6d31c5e2db2439d316374f'/>
<id>urn:sha1:6aee4badd8126f3a2b6d31c5e2db2439d316374f</id>
<content type='text'>
Pull openat2 support from Al Viro:
 "This is the openat2() series from Aleksa Sarai.

  I'm afraid that the rest of namei stuff will have to wait - it got
  zero review the last time I'd posted #work.namei, and there had been a
  leak in the posted series I'd caught only last weekend. I was going to
  repost it on Monday, but the window opened and the odds of getting any
  review during that... Oh, well.

  Anyway, openat2 part should be ready; that _did_ get sane amount of
  review and public testing, so here it comes"

From Aleksa's description of the series:
 "For a very long time, extending openat(2) with new features has been
  incredibly frustrating. This stems from the fact that openat(2) is
  possibly the most famous counter-example to the mantra "don't silently
  accept garbage from userspace" -- it doesn't check whether unknown
  flags are present[1].

  This means that (generally) the addition of new flags to openat(2) has
  been fraught with backwards-compatibility issues (O_TMPFILE has to be
  defined as __O_TMPFILE|O_DIRECTORY|[O_RDWR or O_WRONLY] to ensure old
  kernels gave errors, since it's insecure to silently ignore the
  flag[2]). All new security-related flags therefore have a tough road
  to being added to openat(2).

  Furthermore, the need for some sort of control over VFS's path
  resolution (to avoid malicious paths resulting in inadvertent
  breakouts) has been a very long-standing desire of many userspace
  applications.

  This patchset is a revival of Al Viro's old AT_NO_JUMPS[3] patchset
  (which was a variant of David Drysdale's O_BENEATH patchset[4] which
  was a spin-off of the Capsicum project[5]) with a few additions and
  changes made based on the previous discussion within [6] as well as
  others I felt were useful.

  In line with the conclusions of the original discussion of
  AT_NO_JUMPS, the flag has been split up into separate flags. However,
  instead of being an openat(2) flag it is provided through a new
  syscall openat2(2) which provides several other improvements to the
  openat(2) interface (see the patch description for more details). The
  following new LOOKUP_* flags are added:

  LOOKUP_NO_XDEV:

     Blocks all mountpoint crossings (upwards, downwards, or through
     absolute links). Absolute pathnames alone in openat(2) do not
     trigger this. Magic-link traversal which implies a vfsmount jump is
     also blocked (though magic-link jumps on the same vfsmount are
     permitted).

  LOOKUP_NO_MAGICLINKS:

     Blocks resolution through /proc/$pid/fd-style links. This is done
     by blocking the usage of nd_jump_link() during resolution in a
     filesystem. The term "magic-links" is used to match with the only
     reference to these links in Documentation/, but I'm happy to change
     the name.

     It should be noted that this is different to the scope of
     ~LOOKUP_FOLLOW in that it applies to all path components. However,
     you can do openat2(NO_FOLLOW|NO_MAGICLINKS) on a magic-link and it
     will *not* fail (assuming that no parent component was a
     magic-link), and you will have an fd for the magic-link.

     In order to correctly detect magic-links, the introduction of a new
     LOOKUP_MAGICLINK_JUMPED state flag was required.

  LOOKUP_BENEATH:

     Disallows escapes to outside the starting dirfd's
     tree, using techniques such as ".." or absolute links. Absolute
     paths in openat(2) are also disallowed.

     Conceptually this flag is to ensure you "stay below" a certain
     point in the filesystem tree -- but this requires some additional
     to protect against various races that would allow escape using
     "..".

     Currently LOOKUP_BENEATH implies LOOKUP_NO_MAGICLINKS, because it
     can trivially beam you around the filesystem (breaking the
     protection). In future, there might be similar safety checks done
     as in LOOKUP_IN_ROOT, but that requires more discussion.

  In addition, two new flags are added that expand on the above ideas:

  LOOKUP_NO_SYMLINKS:

     Does what it says on the tin. No symlink resolution is allowed at
     all, including magic-links. Just as with LOOKUP_NO_MAGICLINKS this
     can still be used with NOFOLLOW to open an fd for the symlink as
     long as no parent path had a symlink component.

  LOOKUP_IN_ROOT:

     This is an extension of LOOKUP_BENEATH that, rather than blocking
     attempts to move past the root, forces all such movements to be
     scoped to the starting point. This provides chroot(2)-like
     protection but without the cost of a chroot(2) for each filesystem
     operation, as well as being safe against race attacks that
     chroot(2) is not.

     If a race is detected (as with LOOKUP_BENEATH) then an error is
     generated, and similar to LOOKUP_BENEATH it is not permitted to
     cross magic-links with LOOKUP_IN_ROOT.

     The primary need for this is from container runtimes, which
     currently need to do symlink scoping in userspace[7] when opening
     paths in a potentially malicious container.

     There is a long list of CVEs that could have bene mitigated by
     having RESOLVE_THIS_ROOT (such as CVE-2017-1002101,
     CVE-2017-1002102, CVE-2018-15664, and CVE-2019-5736, just to name a
     few).

  In order to make all of the above more usable, I'm working on
  libpathrs[8] which is a C-friendly library for safe path resolution.
  It features a userspace-emulated backend if the kernel doesn't support
  openat2(2). Hopefully we can get userspace to switch to using it, and
  thus get openat2(2) support for free once it's ready.

  Future work would include implementing things like
  RESOLVE_NO_AUTOMOUNT and possibly a RESOLVE_NO_REMOTE (to allow
  programs to be sure they don't hit DoSes though stale NFS handles)"

* 'work.openat2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  Documentation: path-lookup: include new LOOKUP flags
  selftests: add openat2(2) selftests
  open: introduce openat2(2) syscall
  namei: LOOKUP_{IN_ROOT,BENEATH}: permit limited ".." resolution
  namei: LOOKUP_IN_ROOT: chroot-like scoped resolution
  namei: LOOKUP_BENEATH: O_BENEATH-like scoped resolution
  namei: LOOKUP_NO_XDEV: block mountpoint crossing
  namei: LOOKUP_NO_MAGICLINKS: block magic-link resolution
  namei: LOOKUP_NO_SYMLINKS: block symlink resolution
  namei: allow set_root() to produce errors
  namei: allow nd_jump_link() to produce errors
  nsfs: clean-up ns_get_path() signature to return int
  namei: only return -ECHILD from follow_dotdot_rcu()
</content>
</entry>
<entry>
<title>open: introduce openat2(2) syscall</title>
<updated>2020-01-18T14:19:18Z</updated>
<author>
<name>Aleksa Sarai</name>
<email>cyphar@cyphar.com</email>
</author>
<published>2020-01-18T12:07:59Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=fddb5d430ad9fa91b49b1d34d0202ffe2fa0e179'/>
<id>urn:sha1:fddb5d430ad9fa91b49b1d34d0202ffe2fa0e179</id>
<content type='text'>
/* Background. */
For a very long time, extending openat(2) with new features has been
incredibly frustrating. This stems from the fact that openat(2) is
possibly the most famous counter-example to the mantra "don't silently
accept garbage from userspace" -- it doesn't check whether unknown flags
are present[1].

This means that (generally) the addition of new flags to openat(2) has
been fraught with backwards-compatibility issues (O_TMPFILE has to be
defined as __O_TMPFILE|O_DIRECTORY|[O_RDWR or O_WRONLY] to ensure old
kernels gave errors, since it's insecure to silently ignore the
flag[2]). All new security-related flags therefore have a tough road to
being added to openat(2).

Userspace also has a hard time figuring out whether a particular flag is
supported on a particular kernel. While it is now possible with
contemporary kernels (thanks to [3]), older kernels will expose unknown
flag bits through fcntl(F_GETFL). Giving a clear -EINVAL during
openat(2) time matches modern syscall designs and is far more
fool-proof.

In addition, the newly-added path resolution restriction LOOKUP flags
(which we would like to expose to user-space) don't feel related to the
pre-existing O_* flag set -- they affect all components of path lookup.
We'd therefore like to add a new flag argument.

Adding a new syscall allows us to finally fix the flag-ignoring problem,
and we can make it extensible enough so that we will hopefully never
need an openat3(2).

/* Syscall Prototype. */
  /*
   * open_how is an extensible structure (similar in interface to
   * clone3(2) or sched_setattr(2)). The size parameter must be set to
   * sizeof(struct open_how), to allow for future extensions. All future
   * extensions will be appended to open_how, with their zero value
   * acting as a no-op default.
   */
  struct open_how { /* ... */ };

  int openat2(int dfd, const char *pathname,
              struct open_how *how, size_t size);

/* Description. */
The initial version of 'struct open_how' contains the following fields:

  flags
    Used to specify openat(2)-style flags. However, any unknown flag
    bits or otherwise incorrect flag combinations (like O_PATH|O_RDWR)
    will result in -EINVAL. In addition, this field is 64-bits wide to
    allow for more O_ flags than currently permitted with openat(2).

  mode
    The file mode for O_CREAT or O_TMPFILE.

    Must be set to zero if flags does not contain O_CREAT or O_TMPFILE.

  resolve
    Restrict path resolution (in contrast to O_* flags they affect all
    path components). The current set of flags are as follows (at the
    moment, all of the RESOLVE_ flags are implemented as just passing
    the corresponding LOOKUP_ flag).

    RESOLVE_NO_XDEV       =&gt; LOOKUP_NO_XDEV
    RESOLVE_NO_SYMLINKS   =&gt; LOOKUP_NO_SYMLINKS
    RESOLVE_NO_MAGICLINKS =&gt; LOOKUP_NO_MAGICLINKS
    RESOLVE_BENEATH       =&gt; LOOKUP_BENEATH
    RESOLVE_IN_ROOT       =&gt; LOOKUP_IN_ROOT

open_how does not contain an embedded size field, because it is of
little benefit (userspace can figure out the kernel open_how size at
runtime fairly easily without it). It also only contains u64s (even
though -&gt;mode arguably should be a u16) to avoid having padding fields
which are never used in the future.

Note that as a result of the new how-&gt;flags handling, O_PATH|O_TMPFILE
is no longer permitted for openat(2). As far as I can tell, this has
always been a bug and appears to not be used by userspace (and I've not
seen any problems on my machines by disallowing it). If it turns out
this breaks something, we can special-case it and only permit it for
openat(2) but not openat2(2).

After input from Florian Weimer, the new open_how and flag definitions
are inside a separate header from uapi/linux/fcntl.h, to avoid problems
that glibc has with importing that header.

/* Testing. */
In a follow-up patch there are over 200 selftests which ensure that this
syscall has the correct semantics and will correctly handle several
attack scenarios.

In addition, I've written a userspace library[4] which provides
convenient wrappers around openat2(RESOLVE_IN_ROOT) (this is necessary
because no other syscalls support RESOLVE_IN_ROOT, and thus lots of care
must be taken when using RESOLVE_IN_ROOT'd file descriptors with other
syscalls). During the development of this patch, I've run numerous
verification tests using libpathrs (showing that the API is reasonably
usable by userspace).

/* Future Work. */
Additional RESOLVE_ flags have been suggested during the review period.
These can be easily implemented separately (such as blocking auto-mount
during resolution).

Furthermore, there are some other proposed changes to the openat(2)
interface (the most obvious example is magic-link hardening[5]) which
would be a good opportunity to add a way for userspace to restrict how
O_PATH file descriptors can be re-opened.

Another possible avenue of future work would be some kind of
CHECK_FIELDS[6] flag which causes the kernel to indicate to userspace
which openat2(2) flags and fields are supported by the current kernel
(to avoid userspace having to go through several guesses to figure it
out).

[1]: https://lwn.net/Articles/588444/
[2]: https://lore.kernel.org/lkml/CA+55aFyyxJL1LyXZeBsf2ypriraj5ut1XkNDsunRBqgVjZU_6Q@mail.gmail.com
[3]: commit 629e014bb834 ("fs: completely ignore unknown open flags")
[4]: https://sourceware.org/bugzilla/show_bug.cgi?id=17523
[5]: https://lore.kernel.org/lkml/20190930183316.10190-2-cyphar@cyphar.com/
[6]: https://youtu.be/ggD-eb3yPVs

Suggested-by: Christian Brauner &lt;christian.brauner@ubuntu.com&gt;
Signed-off-by: Aleksa Sarai &lt;cyphar@cyphar.com&gt;
Signed-off-by: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
</content>
</entry>
</feed>
