linux-stable.git/drivers/char, branch linux-5.18.y

tpm: Add check for Failure mode for TPM2 modules

2022-08-17T12:42:32+00:00

[ Upstream commit 863ed94c589fcd1984f4e3080f069d30508044bb ]

In commit 0aa698787aa2 ("tpm: Add Upgrade/Reduced mode support for
TPM2 modules") it was said that:

"If the TPM is in Failure mode, it will successfully respond to both
tpm2_do_selftest() and tpm2_startup() calls. Although, will fail to
answer to tpm2_get_cc_attrs_tbl(). Use this fact to conclude that TPM
is in Failure mode."

But a check was never added in the commit when calling
tpm2_get_cc_attrs_tbl() to conclude that the TPM is in Failure mode.
This commit corrects this by adding a check.

Fixes: 0aa698787aa2 ("tpm: Add Upgrade/Reduced mode support for TPM2 modules")
Cc: stable@vger.kernel.org # v5.17+
Signed-off-by: Mårten Lindahl 
Reviewed-by: Jarkko Sakkinen 
Signed-off-by: Jarkko Sakkinen 
Signed-off-by: Sasha Levin

random: update comment from copy_to_user() -> copy_to_iter()

2022-06-29T07:04:43+00:00

commit 63b8ea5e4f1a87dea4d3114293fc8e96a8f193d7 upstream.

This comment wasn't updated when we moved from read() to read_iter(), so
this patch makes the trivial fix.

Fixes: 1b388e7765f2 ("random: convert to using fops->read_iter()")
Signed-off-by: Jason A. Donenfeld 
Signed-off-by: Greg Kroah-Hartman

random: quiet urandom warning ratelimit suppression message

2022-06-29T07:04:24+00:00

commit c01d4d0a82b71857be7449380338bc53dde2da92 upstream.

random.c ratelimits how much it warns about uninitialized urandom reads
using __ratelimit(). When the RNG is finally initialized, it prints the
number of missed messages due to ratelimiting.

It has been this way since that functionality was introduced back in
2018. Recently, cc1e127bfa95 ("random: remove ratelimiting for in-kernel
unseeded randomness") put a bit more stress on the urandom ratelimiting,
which teased out a bug in the implementation.

Specifically, when under pressure, __ratelimit() will print its own
message and reset the count back to 0, making the final message at the
end less useful. Secondly, it does so as a pr_warn(), which apparently
is undesirable for people's CI.

Fortunately, __ratelimit() has the RATELIMIT_MSG_ON_RELEASE flag exactly
for this purpose, so we set the flag.

Fixes: 4e00b339e264 ("random: rate limit unseeded randomness warnings")
Cc: stable@vger.kernel.org
Reported-by: Jon Hunter 
Reported-by: Ron Economos 
Tested-by: Ron Economos 
Signed-off-by: Jason A. Donenfeld 
Signed-off-by: Greg Kroah-Hartman

random: schedule mix_interrupt_randomness() less often

2022-06-29T07:04:24+00:00

commit 534d2eaf1970274150596fdd2bf552721e65d6b2 upstream.

It used to be that mix_interrupt_randomness() would credit 1 bit each
time it ran, and so add_interrupt_randomness() would schedule mix() to
run every 64 interrupts, a fairly arbitrary number, but nonetheless
considered to be a decent enough conservative estimate.

Since e3e33fc2ea7f ("random: do not use input pool from hard IRQs"),
mix() is now able to credit multiple bits, depending on the number of
calls to add(). This was done for reasons separate from this commit, but
it has the nice side effect of enabling this patch to schedule mix()
less often.

Currently the rules are:
a) Credit 1 bit for every 64 calls to add().
b) Schedule mix() once a second that add() is called.
c) Schedule mix() once every 64 calls to add().

Rules (a) and (c) no longer need to be coupled. It's still important to
have _some_ value in (c), so that we don't "over-saturate" the fast
pool, but the once per second we get from rule (b) is a plenty enough
baseline. So, by increasing the 64 in rule (c) to something larger, we
avoid calling queue_work_on() as frequently during irq storms.

This commit changes that 64 in rule (c) to be 1024, which means we
schedule mix() 16 times less often. And it does *not* need to change the
64 in rule (a).

Fixes: 58340f8e952b ("random: defer fast pool mixing to worker")
Cc: stable@vger.kernel.org
Cc: Dominik Brodowski 
Acked-by: Sebastian Andrzej Siewior 
Signed-off-by: Jason A. Donenfeld 
Signed-off-by: Greg Kroah-Hartman

random: credit cpu and bootloader seeds by default

2022-06-22T12:27:55+00:00

[ Upstream commit 846bb97e131d7938847963cca00657c995b1fce1 ]

This commit changes the default Kconfig values of RANDOM_TRUST_CPU and
RANDOM_TRUST_BOOTLOADER to be Y by default. It does not change any
existing configs or change any kernel behavior. The reason for this is
several fold.

As background, I recently had an email thread with the kernel
maintainers of Fedora/RHEL, Debian, Ubuntu, Gentoo, Arch, NixOS, Alpine,
SUSE, and Void as recipients. I noted that some distros trust RDRAND,
some trust EFI, and some trust both, and I asked why or why not. There
wasn't really much of a "debate" but rather an interesting discussion of
what the historical reasons have been for this, and it came up that some
distros just missed the introduction of the bootloader Kconfig knob,
while another didn't want to enable it until there was a boot time
switch to turn it off for more concerned users (which has since been
added). The result of the rather uneventful discussion is that every
major Linux distro enables these two options by default.

While I didn't have really too strong of an opinion going into this
thread -- and I mostly wanted to learn what the distros' thinking was
one way or another -- ultimately I think their choice was a decent
enough one for a default option (which can be disabled at boot time).
I'll try to summarize the pros and cons:

Pros:

- The RNG machinery gets initialized super quickly, and there's no
  messing around with subsequent blocking behavior.

- The bootloader mechanism is used by kexec in order for the prior
  kernel to initialize the RNG of the next kernel, which increases
  the entropy available to early boot daemons of the next kernel.

- Previous objections related to backdoors centered around
  Dual_EC_DRBG-like kleptographic systems, in which observing some
  amount of the output stream enables an adversary holding the right key
  to determine the entire output stream.

  This used to be a partially justified concern, because RDRAND output
  was mixed into the output stream in varying ways, some of which may
  have lacked pre-image resistance (e.g. XOR or an LFSR).

  But this is no longer the case. Now, all usage of RDRAND and
  bootloader seeds go through a cryptographic hash function. This means
  that the CPU would have to compute a hash pre-image, which is not
  considered to be feasible (otherwise the hash function would be
  terribly broken).

- More generally, if the CPU is backdoored, the RNG is probably not the
  realistic vector of choice for an attacker.

- These CPU or bootloader seeds are far from being the only source of
  entropy. Rather, there is generally a pretty huge amount of entropy,
  not all of which is credited, especially on CPUs that support
  instructions like RDRAND. In other words, assuming RDRAND outputs all
  zeros, an attacker would *still* have to accurately model every single
  other entropy source also in use.

- The RNG now reseeds itself quite rapidly during boot, starting at 2
  seconds, then 4, then 8, then 16, and so forth, so that other sources
  of entropy get used without much delay.

- Paranoid users can set random.trust_{cpu,bootloader}=no in the kernel
  command line, and paranoid system builders can set the Kconfig options
  to N, so there's no reduction or restriction of optionality.

- It's a practical default.

- All the distros have it set this way. Microsoft and Apple trust it
  too. Bandwagon.

Cons:

- RDRAND *could* still be backdoored with something like a fixed key or
  limited space serial number seed or another indexable scheme like
  that. (However, it's hard to imagine threat models where the CPU is
  backdoored like this, yet people are still okay making *any*
  computations with it or connecting it to networks, etc.)

- RDRAND *could* be defective, rather than backdoored, and produce
  garbage that is in one way or another insufficient for crypto.

- Suggesting a *reduction* in paranoia, as this commit effectively does,
  may cause some to question my personal integrity as a "security
  person".

- Bootloader seeds and RDRAND are generally very difficult if not all
  together impossible to audit.

Keep in mind that this doesn't actually change any behavior. This
is just a change in the default Kconfig value. The distros already are
shipping kernels that set things this way.

Ard made an additional argument in [1]:

    We're at the mercy of firmware and micro-architecture anyway, given
    that we are also relying on it to ensure that every instruction in
    the kernel's executable image has been faithfully copied to memory,
    and that the CPU implements those instructions as documented. So I
    don't think firmware or ISA bugs related to RNGs deserve special
    treatment - if they are broken, we should quirk around them like we
    usually do. So enabling these by default is a step in the right
    direction IMHO.

In [2], Phil pointed out that having this disabled masked a bug that CI
otherwise would have caught:

    A clean 5.15.45 boots cleanly, whereas a downstream kernel shows the
    static key warning (but it does go on to boot). The significant
    difference is that our defconfigs set CONFIG_RANDOM_TRUST_BOOTLOADER=y
    defining that on top of multi_v7_defconfig demonstrates the issue on
    a clean 5.15.45. Conversely, not setting that option in a
    downstream kernel build avoids the warning

[1] https://lore.kernel.org/lkml/CAMj1kXGi+ieviFjXv9zQBSaGyyzeGW_VpMpTLJK8PJb2QHEQ-w@mail.gmail.com/
[2] https://lore.kernel.org/lkml/c47c42e3-1d56-5859-a6ad-976a1a3381c6@raspberrypi.com/

Cc: Theodore Ts'o 
Reviewed-by: Ard Biesheuvel 
Signed-off-by: Jason A. Donenfeld 
Signed-off-by: Sasha Levin

random: account for arch randomness in bits

2022-06-14T16:45:20+00:00

commit 77fc95f8c0dc9e1f8e620ec14d2fb65028fb7adc upstream.

Rather than accounting in bytes and multiplying (shifting), we can just
account in bits and avoid the shift. The main motivation for this is
there are other patches in flux that expand this code a bit, and
avoiding the duplication of "* 8" everywhere makes things a bit clearer.

Cc: stable@vger.kernel.org
Fixes: 12e45a2a6308 ("random: credit architectural init the exact amount")
Signed-off-by: Jason A. Donenfeld 
Signed-off-by: Greg Kroah-Hartman

random: mark bootloader randomness code as __init

2022-06-14T16:45:20+00:00

commit 39e0f991a62ed5efabd20711a7b6e7da92603170 upstream.

add_bootloader_randomness() and the variables it touches are only used
during __init and not after, so mark these as __init. At the same time,
unexport this, since it's only called by other __init code that's
built-in.

Cc: stable@vger.kernel.org
Fixes: 428826f5358c ("fdt: add support for rng-seed")
Signed-off-by: Jason A. Donenfeld 
Signed-off-by: Greg Kroah-Hartman

random: avoid checking crng_ready() twice in random_init()

2022-06-14T16:45:20+00:00

commit 9b29b6b20376ab64e1b043df6301d8a92378e631 upstream.

The current flow expands to:

    if (crng_ready())
       ...
    else if (...)
        if (!crng_ready())
            ...

The second crng_ready() call is redundant, but can't so easily be
optimized out by the compiler.

This commit simplifies that to:

    if (crng_ready()
        ...
    else if (...)
        ...

Fixes: 560181c27b58 ("random: move initialization functions out of hot pages")
Cc: stable@vger.kernel.org
Cc: Dominik Brodowski 
Signed-off-by: Jason A. Donenfeld 
Signed-off-by: Greg Kroah-Hartman

virtio-rng: make device ready before making request

2022-06-14T16:45:20+00:00

commit 228432551bd8783211e494ab35f42a4344580502 upstream.

Current virtio-rng does a entropy request before DRIVER_OK, this
violates the spec:

virtio spec requires that all drivers set DRIVER_OK
before using devices.

Further, kernel will ignore the interrupt after commit
8b4ec69d7e09 ("virtio: harden vring IRQ").

Fixing this by making device ready before the request.

Cc: stable@vger.kernel.org
Fixes: 8b4ec69d7e09 ("virtio: harden vring IRQ")
Fixes: f7f510ec1957 ("virtio: An entropy device, as suggested by hpa.")
Reported-and-tested-by: syzbot+5b59d6d459306a556f54@syzkaller.appspotmail.com
Signed-off-by: Jason Wang 
Message-Id: <20220608061422.38437-1-jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin 
Reviewed-by: Laurent Vivier 
Signed-off-by: Greg Kroah-Hartman

char: xillybus: fix a refcount leak in cleanup_dev()

2022-06-14T16:45:10+00:00

[ Upstream commit b67d19662fdee275c479d21853bc1239600a798f ]

usb_get_dev is called in xillyusb_probe. So it is better to call
usb_put_dev before xdev is released.

Acked-by: Eli Billauer 
Signed-off-by: Hangyu Hua 
Link: https://lore.kernel.org/r/20220406075703.23464-1-hbh25y@gmail.com
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin