The use of kmap() is being deprecated in favor of kmap_local_page().
Two main problems with kmap(): (1) It comes with an overhead as mapping
space is restricted and protected by a global lock for synchronization and
(2) kmap() also requires global TLB invalidation when the kmap’s pool
wraps and it might block when the mapping space is fully utilized until a
slot becomes available.
kmap_local_page() is preferred over kmap() and kmap_atomic(). Where it
cannot mechanically replace the latters, code refactor should be considered
(special care must be taken if kernel virtual addresses are aliases in
different contexts).
With kmap_local_page() the mappings are per thread, CPU local, can take
page faults, and can be called from any context (including interrupts).
Call kmap_local_page() in firmware_loader wherever kmap() is currently
used. In firmware_rw() use the helpers copy_{from,to}_page() instead of
open coding the local mappings + memcpy().
Successfully tested with "firmware" selftests on a QEMU/KVM 32-bits VM
with 4GB RAM, booting a kernel with HIGHMEM64GB enabled.
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Suggested-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Link: https://lore.kernel.org/r/20220714235030.12732-1-fmdefrancesco@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pull driver core updates from Greg KH:
"Here is the set of driver core changes for 5.19-rc1.
Lots of tiny driver core changes and cleanups happened this cycle, but
the two major things are:
- firmware_loader reorganization and additions including the ability
to have XZ compressed firmware images and the ability for userspace
to initiate the firmware load when it needs to, instead of being
always initiated by the kernel. FPGA devices specifically want this
ability to have their firmware changed over the lifetime of the
system boot, and this allows them to work without having to come up
with yet-another-custom-uapi interface for loading firmware for
them.
- physical location support added to sysfs so that devices that know
this information, can tell userspace where they are located in a
common way. Some ACPI devices already support this today, and more
bus types should support this in the future.
Smaller changes include:
- driver_override api cleanups and fixes
- error path cleanups and fixes
- get_abi script fixes
- deferred probe timeout changes.
It's that last change that I'm the most worried about. It has been
reported to cause boot problems for a number of systems, and I have a
tested patch series that resolves this issue. But I didn't get it
merged into my tree before 5.18-final came out, so it has not gotten
any linux-next testing.
I'll send the fixup patches (there are 2) as a follow-on series to this
pull request.
All have been tested in linux-next for weeks, with no reported issues
other than the above-mentioned boot time-outs"
* tag 'driver-core-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (55 commits)
driver core: fix deadlock in __device_attach
kernfs: Separate kernfs_pr_cont_buf and rename_lock.
topology: Remove unused cpu_cluster_mask()
driver core: Extend deferred probe timeout on driver registration
MAINTAINERS: add Russ Weight as a firmware loader maintainer
driver: base: fix UAF when driver_attach failed
test_firmware: fix end of loop test in upload_read_show()
driver core: location: Add "back" as a possible output for panel
driver core: location: Free struct acpi_pld_info *pld
driver core: Add "*" wildcard support to driver_async_probe cmdline param
driver core: location: Check for allocations failure
arch_topology: Trace the update thermal pressure
kernfs: Rename kernfs_put_open_node to kernfs_unlink_open_file.
export: fix string handling of namespace in EXPORT_SYMBOL_NS
rpmsg: use local 'dev' variable
rpmsg: Fix calling device_lock() on non-initialized device
firmware_loader: describe 'module' parameter of firmware_upload_register()
firmware_loader: Move definitions from sysfs_upload.h to sysfs.h
firmware_loader: Fix configs for sysfs split
selftests: firmware: Add firmware upload selftests
...
Device drivers may decide to not load firmware when probed to avoid
slowing down the boot process should the firmware filesystem not be
available yet. In this case, the firmware loading request may be done
when a device file associated with the driver is first accessed. The
credentials of the userspace process accessing the device file may be
used to validate access to the firmware files requested by the driver.
Ensure that the kernel assumes the responsibility of reading the
firmware.
This was observed on Android for a graphic driver loading their firmware
when the device file (e.g. /dev/mali0) was first opened by userspace
(i.e. surfaceflinger). The security context of surfaceflinger was used
to validate the access to the firmware file (e.g.
/vendor/firmware/mali.bin).
Previously, Android configurations were not setting up the
firmware_class.path command line argument and were relying on the
userspace fallback mechanism. In this case, the security context of the
userspace daemon (i.e. ueventd) was consistently used to read firmware
files. More Android devices are now found to set firmware_class.path
which gives the kernel the opportunity to read the firmware directly
(via kernel_read_file_from_path_initns). In this scenario, the current
process credentials were used, even if unrelated to the loading of the
firmware file.
Signed-off-by: Thiébaud Weksteen <tweek@google.com>
Cc: <stable@vger.kernel.org> # 5.10
Reviewed-by: Paul Moore <paul@paul-moore.com>
Acked-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20220502004952.3970800-1-tweek@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Extend the firmware subsystem to support a persistent sysfs interface that
userspace may use to initiate a firmware update. For example, FPGA based
PCIe cards load firmware and FPGA images from local FLASH when the card
boots. The images in FLASH may be updated with new images provided by the
user at his/her convenience.
A device driver may call firmware_upload_register() to expose persistent
"loading" and "data" sysfs files. These files are used in the same way as
the fallback sysfs "loading" and "data" files. When 0 is written to
"loading" to complete the write of firmware data, the data is transferred
to the lower-level driver using pre-registered call-back functions. The
data transfer is done in the context of a kernel worker thread.
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Tianfei zhang <tianfei.zhang@intel.com>
Tested-by: Matthew Gerlach <matthew.gerlach@linux.intel.com>
Signed-off-by: Russ Weight <russell.h.weight@intel.com>
Link: https://lore.kernel.org/r/20220421212204.36052-5-russell.h.weight@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Device drivers may decide to not load firmware when probed to avoid
slowing down the boot process should the firmware filesystem not be
available yet. In this case, the firmware loading request may be done
when a device file associated with the driver is first accessed. The
credentials of the userspace process accessing the device file may be
used to validate access to the firmware files requested by the driver.
Ensure that the kernel assumes the responsibility of reading the
firmware.
This was observed on Android for a graphic driver loading their firmware
when the device file (e.g. /dev/mali0) was first opened by userspace
(i.e. surfaceflinger). The security context of surfaceflinger was used
to validate the access to the firmware file (e.g.
/vendor/firmware/mali.bin).
Because previous configurations were relying on the userspace fallback
mechanism, the security context of the userspace daemon (i.e. ueventd)
was consistently used to read firmware files. More devices are found to
use the command line argument firmware_class.path which gives the kernel
the opportunity to read the firmware directly, hence surfacing this
misattribution.
Signed-off-by: Thiébaud Weksteen <tweek@google.com>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Tested-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/r/20220422013215.2301793-1-tweek@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Formalize the built-in firmware with a proper API. This can later
be used by other callers where all they need is built-in firmware.
We export the firmware_request_builtin() call for now only
under the TEST_FIRMWARE symbol namespace as there are no
direct modular users for it. If they pop up they are free
to export it generally. Built-in code always gets access to
the callers and we'll demonstrate a hidden user which has been
lurking in the kernel for a while and the reason why using a
proper API was better long term.
Reviewed-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20211021155843.1969401-2-mcgrof@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Right now firmware_request_builtin() is used internally only
and so we have control over the callers. But if we want to expose
that API more broadly we should ensure the firmware pointer
is valid.
This doesn't fix any known issue, it just prepares us to later
expose this API to other users.
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20210917182226.3532898-4-mcgrof@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
There are two ways the firmware_loader can use the built-in
firmware: with or without the pre-allocated buffer. We already
have one explicit use case for each of these, and so split them
up so that it is clear what the intention is on the caller side.
This also paves the way so that eventually other callers outside
of the firmware loader can uses these if and when needed.
While at it, adopt the firmware prefix for the routine names.
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20210917182226.3532898-3-mcgrof@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The firmware_loader can be used with a pre-allocated buffer
through the use of the API calls:
o request_firmware_into_buf()
o request_partial_firmware_into_buf()
If the firmware was built-in and present, our current check
for if the built-in firmware fits into the pre-allocated buffer
does not return any errors, and we proceed to tell the caller
that everything worked fine. It's a lie and no firmware would
end up being copied into the pre-allocated buffer. So if the
caller trust the result it may end up writing a bunch of 0's
to a device!
Fix this by making the function that checks for the pre-allocated
buffer return non-void. Since the typical use case is when no
pre-allocated buffer is provided make this return successfully
for that case. If the built-in firmware does *not* fit into the
pre-allocated buffer size return a failure as we should have
been doing before.
I'm not aware of users of the built-in firmware using the API
calls with a pre-allocated buffer, as such I doubt this fixes
any real life issue. But you never know... perhaps some oddball
private tree might use it.
In so far as upstream is concerned this just fixes our code for
correctness.
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20210917182226.3532898-2-mcgrof@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This use-after-free happens when a fw_priv object has been freed but
hasn't been removed from the pending list (pending_fw_head). The next
time fw_load_sysfs_fallback tries to insert into the list, it ends up
accessing the pending_list member of the previously freed fw_priv.
The root cause here is that all code paths that abort the fw load
don't delete it from the pending list. For example:
_request_firmware()
-> fw_abort_batch_reqs()
-> fw_state_aborted()
To fix this, delete the fw_priv from the list in __fw_set_state() if
the new state is DONE or ABORTED. This way, all aborts will remove
the fw_priv from the list. Accordingly, remove calls to list_del_init
that were being made before calling fw_state_(aborted|done).
Also, in fw_load_sysfs_fallback, don't add the fw_priv to the pending
list if it is already aborted. Instead, just jump out and return early.
Fixes: bcfbd3523f ("firmware: fix a double abort case with fw_load_sysfs_fallback")
Cc: stable <stable@vger.kernel.org>
Reported-by: syzbot+de271708674e2093097b@syzkaller.appspotmail.com
Tested-by: syzbot+de271708674e2093097b@syzkaller.appspotmail.com
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Acked-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Anirudh Rayabharam <mail@anirudhrb.com>
Link: https://lore.kernel.org/r/20210728085107.4141-3-mail@anirudhrb.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This race was discovered when I carefully analyzed the code to locate
another firmware-related UAF issue. It can be triggered only when the
firmware load operation is executed during suspend. This possibility is
almost impossible because there are few firmware load and suspend actions
in the actual environment.
CPU0 CPU1
__device_uncache_fw_images(): assign_fw():
fw_cache_piggyback_on_request()
<----- P0
spin_lock(&fwc->name_lock);
...
list_del(&fce->list);
spin_unlock(&fwc->name_lock);
uncache_firmware(fce->name);
<----- P1
kref_get(&fw_priv->ref);
If CPU1 is interrupted at position P0, the new 'fce' has been added to the
list fwc->fw_names by the fw_cache_piggyback_on_request(). In this case,
CPU0 executes __device_uncache_fw_images() and will be able to see it when
it traverses list fwc->fw_names. Before CPU1 executes kref_get() at P1, if
CPU0 further executes uncache_firmware(), the count of fw_priv->ref may
decrease to 0, causing fw_priv to be released in advance.
Move kref_get() to the lock protection range of fwc->name_lock to fix it.
Fixes: ac39b3ea73 ("firmware loader: let caching firmware piggyback on loading firmware")
Acked-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Link: https://lore.kernel.org/r/20210719064531.3733-2-thunder.leizhen@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Patch series "background initramfs unpacking, and CONFIG_MODPROBE_PATH", v3.
These two patches are independent, but better-together.
The second is a rather trivial patch that simply allows the developer to
change "/sbin/modprobe" to something else - e.g. the empty string, so
that all request_module() during early boot return -ENOENT early, without
even spawning a usermode helper, needlessly synchronizing with the
initramfs unpacking.
The first patch delegates decompressing the initramfs to a worker thread,
allowing do_initcalls() in main.c to proceed to the device_ and late_
initcalls without waiting for that decompression (and populating of
rootfs) to finish. Obviously, some of those later calls may rely on the
initramfs being available, so I've added synchronization points in the
firmware loader and usermodehelper paths - there might be other places
that would need this, but so far no one has been able to think of any
places I have missed.
There's not much to win if most of the functionality needed during boot is
only available as modules. But systems with a custom-made .config and
initramfs can boot faster, partly due to utilizing more than one cpu
earlier, partly by avoiding known-futile modprobe calls (which would still
trigger synchronization with the initramfs unpacking, thus eliminating
most of the first benefit).
This patch (of 2):
Most of the boot process doesn't actually need anything from the
initramfs, until of course PID1 is to be executed. So instead of doing
the decompressing and populating of the initramfs synchronously in
populate_rootfs() itself, push that off to a worker thread.
This is primarily motivated by an embedded ppc target, where unpacking
even the rather modest sized initramfs takes 0.6 seconds, which is long
enough that the external watchdog becomes unhappy that it doesn't get
attention soon enough. By doing the initramfs decompression in a worker
thread, we get to do the device_initcalls and hence start petting the
watchdog much sooner.
Normal desktops might benefit as well. On my mostly stock Ubuntu kernel,
my initramfs is a 26M xz-compressed blob, decompressing to around 126M.
That takes almost two seconds:
[ 0.201454] Trying to unpack rootfs image as initramfs...
[ 1.976633] Freeing initrd memory: 29416K
Before this patch, these lines occur consecutively in dmesg. With this
patch, the timestamps on these two lines is roughly the same as above, but
with 172 lines inbetween - so more than one cpu has been kept busy doing
work that would otherwise only happen after the populate_rootfs()
finished.
Should one of the initcalls done after rootfs_initcall time (i.e., device_
and late_ initcalls) need something from the initramfs (say, a kernel
module or a firmware blob), it will simply wait for the initramfs
unpacking to be done before proceeding, which should in theory make this
completely safe.
But if some driver pokes around in the filesystem directly and not via one
of the official kernel interfaces (i.e. request_firmware*(),
call_usermodehelper*) that theory may not hold - also, I certainly might
have missed a spot when sprinkling wait_for_initramfs(). So there is an
escape hatch in the form of an initramfs_async= command line parameter.
Link: https://lkml.kernel.org/r/20210313212528.2956377-1-linux@rasmusvillemoes.dk
Link: https://lkml.kernel.org/r/20210313212528.2956377-2-linux@rasmusvillemoes.dk
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Cc: Jessica Yu <jeyu@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
To perform partial reads, callers of kernel_read_file*() must have a
non-NULL file_size argument and a preallocated buffer. The new "offset"
argument can then be used to seek to specific locations in the file to
fill the buffer to, at most, "buf_size" per call.
Where possible, the LSM hooks can report whether a full file has been
read or not so that the contents can be reasoned about.
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20201002173828.2099543-14-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Fabio M. De Francesco
Linus Torvalds
Thiébaud Weksteen
Greg Kroah-Hartman
Russ Weight
Takashi Iwai
Luis Chamberlain
Anirudh Rayabharam
Zhen Lei
Rasmus Villemoes
Scott Branden
Kees Cook
Prateek Sood
Wolfram Sang