linux-toradex.git/drivers/usb/misc/chaoskey.c, branch v6.2-rc3

hwrng: core - treat default_quality as a maximum and default to 1024

2022-11-18T08:59:34+00:00

Most hw_random devices return entropy which is assumed to be of full
quality, but driver authors don't bother setting the quality knob. Some
hw_random devices return less than full quality entropy, and then driver
authors set the quality knob. Therefore, the entropy crediting should be
opt-out rather than opt-in per-driver, to reflect the actual reality on
the ground.

For example, the two Raspberry Pi RNG drivers produce full entropy
randomness, and both EDK2 and U-Boot's drivers for these treat them as
such. The result is that EFI then uses these numbers and passes the to
Linux, and Linux credits them as boot, thereby initializing the RNG.
Yet, in Linux, the quality knob was never set to anything, and so on the
chance that Linux is booted without EFI, nothing is ever credited.
That's annoying.

The same pattern appears to repeat itself throughout various drivers. In
fact, very very few drivers have bothered setting quality=1024.

Looking at the git history of existing drivers and corresponding mailing
list discussion, this conclusion tracks. There's been a decent amount of
discussion about drivers that set quality < 1024 -- somebody read and
interepreted a datasheet, or made some back of the envelope calculation
somehow. But there's been very little, if any, discussion about most
drivers where the quality is just set to 1024 or unset (or set to 1000
when the authors misunderstood the API and assumed it was base-10 rather
than base-2); in both cases the intent was fairly clear of, "this is a
hardware random device; it's fine."

So let's invert this logic. A hw_random struct's quality knob now
controls the maximum quality a driver can produce, or 0 to specify 1024.
Then, the module-wide switch called "default_quality" is changed to
represent the maximum quality of any driver. By default it's 1024, and
the quality of any particular driver is then given by:

    min(default_quality, rng->quality ?: 1024);

This way, the user can still turn this off for weird reasons (and we can
replace whatever driver-specific disabling hacks existed in the past),
yet we get proper crediting for relevant RNGs.

Cc: Dominik Brodowski 
Cc: Ard Biesheuvel 
Cc: Herbert Xu 
Signed-off-by: Jason A. Donenfeld 
Signed-off-by: Herbert Xu

USB: chaoskey: fix error case of a timeout

2019-11-11T13:29:39+00:00

In case of a timeout or if a signal aborts a read
communication with the device needs to be ended
lest we overwrite an active URB the next time we
do IO to the device, as the URB may still be active.

Signed-off-by: Oliver Neukum 
Cc: stable 
Link: https://lore.kernel.org/r/20191107142856.16774-1-oneukum@suse.com
Signed-off-by: Greg Kroah-Hartman

USB: chaoskey: fix use-after-free on release

2019-10-10T10:43:19+00:00

The driver was accessing its struct usb_interface in its release()
callback without holding a reference. This would lead to a
use-after-free whenever the device was disconnected while the character
device was still open.

Fixes: 66e3e591891d ("usb: Add driver for Altus Metrum ChaosKey device (v2)")
Cc: stable      # 4.1
Signed-off-by: Johan Hovold 
Link: https://lore.kernel.org/r/20191009153848.8664-3-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman

USB: chaoskey: Use kasprintf() over strcpy()/strcat()

2018-02-22T14:17:05+00:00

Instead of kmalloc() with manually calculated values followed by
multiple strcpy()/strcat() calls, just fold it all into a single
kasprintf() call.

Signed-off-by: Kees Cook 
Reviewed-by: Keith Packard 
Signed-off-by: Greg Kroah-Hartman

USB: misc: chaoskey: Use true and false for boolean values

2018-01-24T07:49:51+00:00

Assign true or false to boolean variables instead of an integer value.

This issue was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva 
Reviewed-by: Keith Packard 
Signed-off-by: Greg Kroah-Hartman

USB: misc: Remove redundant license text

2017-11-04T10:55:38+00:00

Now that the SPDX tag is in all USB files, that identifies the license
in a specific and legally-defined manner.  So the extra GPL text wording
can be removed as it is no longer needed at all.

This is done on a quest to remove the 700+ different ways that files in
the kernel describe the GPL license text.  And there's unneeded stuff
like the address (sometimes incorrect) for the FSF which is never
needed.

No copyright headers or other non-license-description text was removed.

Cc: Keith Packard 
Cc: Juergen Stuber 
Cc: Cesar Miquel 
Cc: Richard Leitner 
Signed-off-by: Greg Kroah-Hartman

USB: add SPDX identifiers to all remaining files in drivers/usb/

2017-11-04T10:48:02+00:00

It's good to have SPDX identifiers in all files to make it easier to
audit the kernel tree for correct licenses.

Update the drivers/usb/ and include/linux/usb* files with the correct
SPDX license identifier based on the license text in the file itself.
The SPDX identifier is a legally binding shorthand, which can be used
instead of the full boiler plate text.

This work is based on a script and data from Thomas Gleixner, Philippe
Ombredanne, and Kate Stewart.

Cc: Thomas Gleixner 
Cc: Kate Stewart 
Cc: Philippe Ombredanne 
Signed-off-by: Greg Kroah-Hartman 
Acked-by: Felipe Balbi 
Acked-by: Johan Hovold 
Signed-off-by: Greg Kroah-Hartman

USB: misc: remove unneeded MODULE_VERSION() usage

2017-07-22T13:56:52+00:00

MODULE_VERSION is useless for in-kernel drivers, so just remove all
usage of it in the USB misc drivers.  Along with this, some
DRIVER_VERSION macros were removed as they are also pointless.

Cc: Keith Packard 
Cc: Juergen Stuber 
Cc: Cesar Miquel 
Acked-by: Richard Leitner 
Signed-off-by: Greg Kroah-Hartman

USB: chaoskey: fix Alea quirk on big-endian hosts

2017-05-17T09:27:41+00:00

Add missing endianness conversion when applying the Alea timeout quirk.

Found using sparse:

	warning: restricted __le16 degrades to integer

Fixes: e4a886e811cd ("hwrng: chaoskey - Fix URB warning due to timeout on Alea")
Cc: stable      # 4.8
Cc: Bob Ham 
Cc: Herbert Xu 
Cc: Keith Packard 
Signed-off-by: Johan Hovold 
Signed-off-by: Greg Kroah-Hartman

USB: chaoskey: refactor endpoint retrieval

2017-03-23T12:53:16+00:00

Use the new endpoint helpers to lookup the required bulk-in endpoint.

Signed-off-by: Johan Hovold 
Reviewed-by: Keith Packard 
Signed-off-by: Greg Kroah-Hartman