Pull notification queue from David Howells:
"This adds a general notification queue concept and adds an event
source for keys/keyrings, such as linking and unlinking keys and
changing their attributes.
Thanks to Debarshi Ray, we do have a pull request to use this to fix a
problem with gnome-online-accounts - as mentioned last time:
https://gitlab.gnome.org/GNOME/gnome-online-accounts/merge_requests/47
Without this, g-o-a has to constantly poll a keyring-based kerberos
cache to find out if kinit has changed anything.
[ There are other notification pending: mount/sb fsinfo notifications
for libmount that Karel Zak and Ian Kent have been working on, and
Christian Brauner would like to use them in lxc, but let's see how
this one works first ]
LSM hooks are included:
- A set of hooks are provided that allow an LSM to rule on whether or
not a watch may be set. Each of these hooks takes a different
"watched object" parameter, so they're not really shareable. The
LSM should use current's credentials. [Wanted by SELinux & Smack]
- A hook is provided to allow an LSM to rule on whether or not a
particular message may be posted to a particular queue. This is
given the credentials from the event generator (which may be the
system) and the watch setter. [Wanted by Smack]
I've provided SELinux and Smack with implementations of some of these
hooks.
WHY
===
Key/keyring notifications are desirable because if you have your
kerberos tickets in a file/directory, your Gnome desktop will monitor
that using something like fanotify and tell you if your credentials
cache changes.
However, we also have the ability to cache your kerberos tickets in
the session, user or persistent keyring so that it isn't left around
on disk across a reboot or logout. Keyrings, however, cannot currently
be monitored asynchronously, so the desktop has to poll for it - not
so good on a laptop. This facility will allow the desktop to avoid the
need to poll.
DESIGN DECISIONS
================
- The notification queue is built on top of a standard pipe. Messages
are effectively spliced in. The pipe is opened with a special flag:
pipe2(fds, O_NOTIFICATION_PIPE);
The special flag has the same value as O_EXCL (which doesn't seem
like it will ever be applicable in this context)[?]. It is given up
front to make it a lot easier to prohibit splice&co from accessing
the pipe.
[?] Should this be done some other way? I'd rather not use up a new
O_* flag if I can avoid it - should I add a pipe3() system call
instead?
The pipe is then configured::
ioctl(fds[1], IOC_WATCH_QUEUE_SET_SIZE, queue_depth);
ioctl(fds[1], IOC_WATCH_QUEUE_SET_FILTER, &filter);
Messages are then read out of the pipe using read().
- It should be possible to allow write() to insert data into the
notification pipes too, but this is currently disabled as the
kernel has to be able to insert messages into the pipe *without*
holding pipe->mutex and the code to make this work needs careful
auditing.
- sendfile(), splice() and vmsplice() are disabled on notification
pipes because of the pipe->mutex issue and also because they
sometimes want to revert what they just did - but one or more
notification messages might've been interleaved in the ring.
- The kernel inserts messages with the wait queue spinlock held. This
means that pipe_read() and pipe_write() have to take the spinlock
to update the queue pointers.
- Records in the buffer are binary, typed and have a length so that
they can be of varying size.
This allows multiple heterogeneous sources to share a common
buffer; there are 16 million types available, of which I've used
just a few, so there is scope for others to be used. Tags may be
specified when a watchpoint is created to help distinguish the
sources.
- Records are filterable as types have up to 256 subtypes that can be
individually filtered. Other filtration is also available.
- Notification pipes don't interfere with each other; each may be
bound to a different set of watches. Any particular notification
will be copied to all the queues that are currently watching for it
- and only those that are watching for it.
- When recording a notification, the kernel will not sleep, but will
rather mark a queue as having lost a message if there's
insufficient space. read() will fabricate a loss notification
message at an appropriate point later.
- The notification pipe is created and then watchpoints are attached
to it, using one of:
keyctl_watch_key(KEY_SPEC_SESSION_KEYRING, fds[1], 0x01);
watch_mount(AT_FDCWD, "/", 0, fd, 0x02);
watch_sb(AT_FDCWD, "/mnt", 0, fd, 0x03);
where in both cases, fd indicates the queue and the number after is
a tag between 0 and 255.
- Watches are removed if either the notification pipe is destroyed or
the watched object is destroyed. In the latter case, a message will
be generated indicating the enforced watch removal.
Things I want to avoid:
- Introducing features that make the core VFS dependent on the
network stack or networking namespaces (ie. usage of netlink).
- Dumping all this stuff into dmesg and having a daemon that sits
there parsing the output and distributing it as this then puts the
responsibility for security into userspace and makes handling
namespaces tricky. Further, dmesg might not exist or might be
inaccessible inside a container.
- Letting users see events they shouldn't be able to see.
TESTING AND MANPAGES
====================
- The keyutils tree has a pipe-watch branch that has keyctl commands
for making use of notifications. Proposed manual pages can also be
found on this branch, though a couple of them really need to go to
the main manpages repository instead.
If the kernel supports the watching of keys, then running "make
test" on that branch will cause the testing infrastructure to spawn
a monitoring process on the side that monitors a notifications pipe
for all the key/keyring changes induced by the tests and they'll
all be checked off to make sure they happened.
https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/keyutils.git/log/?h=pipe-watch
- A test program is provided (samples/watch_queue/watch_test) that
can be used to monitor for keyrings, mount and superblock events.
Information on the notifications is simply logged to stdout"
* tag 'notifications-20200601' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
smack: Implement the watch_key and post_notification hooks
selinux: Implement the watch_key security hook
keys: Make the KEY_NEED_* perms an enum rather than a mask
pipe: Add notification lossage handling
pipe: Allow buffers to be marked read-whole-or-error for notifications
Add sample notification program
watch_queue: Add a key/keyring notification facility
security: Add hooks to rule on setting a watch
pipe: Add general notification queue support
pipe: Add O_NOTIFICATION_PIPE
security: Add a hook for the point of notification insertion
uapi: General notification queue definitions
Pull powerpc updates from Michael Ellerman:
- Support for userspace to send requests directly to the on-chip GZIP
accelerator on Power9.
- Rework of our lockless page table walking (__find_linux_pte()) to
make it safe against parallel page table manipulations without
relying on an IPI for serialisation.
- A series of fixes & enhancements to make our machine check handling
more robust.
- Lots of plumbing to add support for "prefixed" (64-bit) instructions
on Power10.
- Support for using huge pages for the linear mapping on 8xx (32-bit).
- Remove obsolete Xilinx PPC405/PPC440 support, and an associated sound
driver.
- Removal of some obsolete 40x platforms and associated cruft.
- Initial support for booting on Power10.
- Lots of other small features, cleanups & fixes.
Thanks to: Alexey Kardashevskiy, Alistair Popple, Andrew Donnellan,
Andrey Abramov, Aneesh Kumar K.V, Balamuruhan S, Bharata B Rao, Bulent
Abali, Cédric Le Goater, Chen Zhou, Christian Zigotzky, Christophe
JAILLET, Christophe Leroy, Dmitry Torokhov, Emmanuel Nicolet, Erhard F.,
Gautham R. Shenoy, Geoff Levand, George Spelvin, Greg Kurz, Gustavo A.
R. Silva, Gustavo Walbon, Haren Myneni, Hari Bathini, Joel Stanley,
Jordan Niethe, Kajol Jain, Kees Cook, Leonardo Bras, Madhavan
Srinivasan., Mahesh Salgaonkar, Markus Elfring, Michael Neuling, Michal
Simek, Nathan Chancellor, Nathan Lynch, Naveen N. Rao, Nicholas Piggin,
Oliver O'Halloran, Paul Mackerras, Pingfan Liu, Qian Cai, Ram Pai,
Raphael Moreira Zinsly, Ravi Bangoria, Sam Bobroff, Sandipan Das, Segher
Boessenkool, Stephen Rothwell, Sukadev Bhattiprolu, Tyrel Datwyler,
Wolfram Sang, Xiongfeng Wang.
* tag 'powerpc-5.8-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (299 commits)
powerpc/pseries: Make vio and ibmebus initcalls pseries specific
cxl: Remove dead Kconfig options
powerpc: Add POWER10 architected mode
powerpc/dt_cpu_ftrs: Add MMA feature
powerpc/dt_cpu_ftrs: Enable Prefixed Instructions
powerpc/dt_cpu_ftrs: Advertise support for ISA v3.1 if selected
powerpc: Add support for ISA v3.1
powerpc: Add new HWCAP bits
powerpc/64s: Don't set FSCR bits in INIT_THREAD
powerpc/64s: Save FSCR to init_task.thread.fscr after feature init
powerpc/64s: Don't let DT CPU features set FSCR_DSCR
powerpc/64s: Don't init FSCR_DSCR in __init_FSCR()
powerpc/32s: Fix another build failure with CONFIG_PPC_KUAP_DEBUG
powerpc/module_64: Use special stub for _mcount() with -mprofile-kernel
powerpc/module_64: Simplify check for -mprofile-kernel ftrace relocations
powerpc/module_64: Consolidate ftrace code
powerpc/32: Disable KASAN with pages bigger than 16k
powerpc/uaccess: Don't set KUEP by default on book3s/32
powerpc/uaccess: Don't set KUAP by default on book3s/32
powerpc/8xx: Reduce time spent in allow_user_access() and friends
...
Pull media updates from Mauro Carvalho Chehab:
- Media documentation is now split into admin-guide, driver-api and
userspace-api books (a longstanding request from Jon);
- The media Kconfig was reorganized, in order to make easier to select
drivers and their dependencies;
- The testing drivers now has a separate directory;
- added a new driver for Rockchip Video Decoder IP;
- The atomisp staging driver was resurrected. It is meant to work with
4 generations of cameras on Atom-based laptops, tablets and cell
phones. So, it seems worth investing time to cleanup this driver and
making it in good shape.
- Added some V4L2 core ancillary routines to help with h264 codecs;
- Added an ov2740 image sensor driver;
- The si2157 gained support for Analog TV, which, in turn, added
support for some cx231xx and cx23885 boards to also support analog
standards;
- Added some V4L2 controls (V4L2_CID_CAMERA_ORIENTATION and
V4L2_CID_CAMERA_SENSOR_ROTATION) to help identifying where the camera
is located at the device;
- VIDIOC_ENUM_FMT was extended to support MC-centric devices;
- Lots of drivers improvements and cleanups.
* tag 'media/v5.8-1' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media: (503 commits)
media: Documentation: media: Refer to mbus format documentation from CSI-2 docs
media: s5k5baf: Replace zero-length array with flexible-array
media: i2c: imx219: Drop <linux/clk-provider.h> and <linux/clkdev.h>
media: i2c: Add ov2740 image sensor driver
media: ov8856: Implement sensor module revision identification
media: ov8856: Add devicetree support
media: dt-bindings: ov8856: Document YAML bindings
media: dvb-usb: Add Cinergy S2 PCIe Dual Port support
media: dvbdev: Fix tuner->demod media controller link
media: dt-bindings: phy: phy-rockchip-dphy-rx0: move rockchip dphy rx0 bindings out of staging
media: staging: dt-bindings: phy-rockchip-dphy-rx0: remove non-used reg property
media: atomisp: unify the version for isp2401 a0 and b0 versions
media: atomisp: update TODO with the current data
media: atomisp: adjust some code at sh_css that could be broken
media: atomisp: don't produce errs for ignored IRQs
media: atomisp: print IRQ when debugging
media: atomisp: isp_mmu: don't use kmem_cache
media: atomisp: add a notice about possible leak resources
media: atomisp: disable the dynamic and reserved pools
media: atomisp: turn on camera before setting it
...
Make it possible to have a general notification queue built on top of a
standard pipe. Notifications are 'spliced' into the pipe and then read
out. splice(), vmsplice() and sendfile() are forbidden on pipes used for
notifications as post_one_notification() cannot take pipe->mutex. This
means that notifications could be posted in between individual pipe
buffers, making iov_iter_revert() difficult to effect.
The way the notification queue is used is:
(1) An application opens a pipe with a special flag and indicates the
number of messages it wishes to be able to queue at once (this can
only be set once):
pipe2(fds, O_NOTIFICATION_PIPE);
ioctl(fds[0], IOC_WATCH_QUEUE_SET_SIZE, queue_depth);
(2) The application then uses poll() and read() as normal to extract data
from the pipe. read() will return multiple notifications if the
buffer is big enough, but it will not split a notification across
buffers - rather it will return a short read or EMSGSIZE.
Notification messages include a length in the header so that the
caller can split them up.
Each message has a header that describes it:
struct watch_notification {
__u32 type:24;
__u32 subtype:8;
__u32 info;
};
The type indicates the source (eg. mount tree changes, superblock events,
keyring changes, block layer events) and the subtype indicates the event
type (eg. mount, unmount; EIO, EDQUOT; link, unlink). The info field
indicates a number of things, including the entry length, an ID assigned to
a watchpoint contributing to this buffer and type-specific flags.
Supplementary data, such as the key ID that generated an event, can be
attached in additional slots. The maximum message size is 127 bytes.
Messages may not be padded or aligned, so there is no guarantee, for
example, that the notification type will be on a 4-byte bounary.
Signed-off-by: David Howells <dhowells@redhat.com>
Add documentation for the V4L2_CID_CAMERA_SENSOR_ROTATION camera
control. The newly added read-only control reports the rotation
correction to be applied to images before displaying them to the user.
Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Add documentation for the V4L2_CID_CAMERA_ORIENTATION camera
control. The newly added read-only control reports the camera device
orientation relative to the usage orientation of the system the camera
is installed on.
Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Rework the documentation to make it easier for the reader to understand
the differences in behavior of this ioctl between MC and non-MC drivers.
Note the addition of the 'video-node-centric' and 'MC-centric' terms to
help understand what the IO_MC capability really means.
Also mention in the beginning that mbus_code is one of the fields that
application should initialize, and add META_OUTPUT as one of the types that
this ioctl supports (that was never added here when the META_OUTPUT buffer
type was added).
Finally document that EINVAL will be returned if mbus_code is unsupported.
Fixes: e5b6b07a1b ("media: v4l2: Extend VIDIOC_ENUM_FMT to support MC-centric devices")
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
The VIDIOC_ENUM_FMT ioctl enumerates all formats supported by a video
node. For MC-centric devices, its behaviour has always been ill-defined,
with drivers implementing one of the following behaviours:
- No support for VIDIOC_ENUM_FMT at all
- Enumerating all formats supported by the video node, regardless of the
configuration of the pipeline
- Enumerating formats supported by the video node for the active
configuration of the connected subdevice
The first behaviour is obviously useless for applications. The second
behaviour provides the most information, but doesn't offer a way to find
what formats are compatible with a given pipeline configuration. The
third behaviour fixes that, but with the drawback that applications
can't enumerate all supported formats anymore, and have to modify the
active configuration of the pipeline to enumerate formats.
The situation is messy as none of the implemented behaviours are ideal,
and userspace can't predict what will happen as the behaviour is
driver-specific.
To fix this, let's extend the VIDIOC_ENUM_FMT with a missing capability:
enumerating pixel formats for a given media bus code. The media bus code
is passed through the v4l2_fmtdesc structure in a new mbus_code field
(repurposed from the reserved fields). With this capability in place,
applications can enumerate pixel formats for a given media bus code
without modifying the active configuration of the device.
The current behaviour of the ioctl is preserved when the new mbus_code
field is set to 0, ensuring compatibility with existing userspace. The
API extension is documented as mandatory for MC-centric devices (as
advertised through the V4L2_CAP_IO_MC capability), allowing applications
and compliance tools to easily determine the availability of the
VIDIOC_ENUM_FMT extension.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Define the VAS_TX_WIN_OPEN ioctl interface for NX GZIP access
from user space. This interface is used to open GZIP send window and
mmap region which can be used by userspace to send requests to NX
directly with copy/paste instructions.
Signed-off-by: Haren Myneni <haren@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1587114065.2275.1106.camel@hbabu-laptop
The vivi.c driver has long gone, but v4l2-videobuf.rst still
refers to it. Just drop that reference since it is no longer valid
or relevant (videobuf is deprecated).
The QUERYCAP documentation also made a reference to is, but there
vivi could just be replaced by vivid, the vivi successor.
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
In order to make easier for people to navigate between the
three media guides, add cross-references between them
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Newer uAPI docs should be dual-licensed with both GPL
and GFDL. Add a text adding the GPLv2 license text there,
in order to be coherent with the included docs.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
The copyright info is not the most valuable information
there. Move them to the end.
While here, change the copyright to cover up to this
year (2020).
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
There are some uAPI stuff that are driver-specific. Add them
to the main media uAPI body.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Most of the driver-specific documentation is meant to help
users of the media subsystem.
Move them to the admin-guide.
It should be noticed, however, that several of those files
are outdated and will require further work in order to make
them useful again.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
This file gives a hint about how fourcc should be named.
It is on a very weird place, as such kind of thing belongs to the
uAPI guide.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Since 2017, there is an space reserved for userspace API,
created by changeset 1d596dee38 ("docs: Create a user-space API guide").
As the media subsystem was one of the first subsystems to use
Sphinx, until this patch, we were keeping things on a separate
place.
Let's just use the new location, as having all uAPI altogether
will likely make things easier for developers.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Linus Torvalds
David Howells
Jacopo Mondi
Hans Verkuil
Hans Verkuil
Laurent Pinchart
Niklas Söderlund
Maheshwar Ajja
Oded Gabbay
Haren Myneni
Mauro Carvalho Chehab
Dafna Hirschfeld