AF_ALG is almost completely unnecessary, and it exposes a massive attack
surface that hasn't been standing up to modern vulnerability discovery
tools. The latest one even has its own website, providing a small
Python script that reliably roots most Linux distros: https://copy.fail/
This isn't sustainable, especially as LLMs have accelerated the rate the
vulnerabilities are coming in. The effort that is being put into this
thing is vastly disproportional to the few programs that actually use
it, and those programs would be better served by userspace code anyway.
These issues have been noted in many mailing list discussions already.
But until now they haven't been reflected in the documentation or
kconfig menu itself, and the vulnerabilities are still coming in.
Let's go ahead and document the deprecation.
This isn't intended to change anything overnight. After all, most Linux
distros won't be able to disable the kconfig options quite yet, mainly
because of iwd. But this should create a bit more impetus for these
userspace programs to be fixed, and the documentation update should also
help prevent more users from appearing.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Commit 8006aff155 ("crypto: atmel-sha204a - Set hwrng quality to
lowest possible") reduced the hwrng quality to 1 based on a review by
Bill Cox [1]. However, despite its title, the review only tested the
ATSHA204, not the ATSHA204A.
In the same thread, Atmel engineer Landon Cox wrote "this behavior has
been eliminated entirely"[2] in the ATSHA204A and "this problem does not
affect the ATECC108 or the ATECC108A (or the ATSHA204A)"[3].
According to the official ATSHA204A datasheet [4], the device contains a
high-quality hardware RNG that combines its output with an internal seed
value stored in EEPROM or SRAM to generate random numbers. The device
also implements all security functions using SHA-256, and the driver
uses the chip's Random command in seed-update mode.
Keep 'quality = 1' for ATSHA204, but drop the explicit hwrng quality
reduction for ATSHA204A and fall back to the hwrng core default.
[1] https://www.metzdowd.com/pipermail/cryptography/2014-December/023858.html
[2] https://www.metzdowd.com/pipermail/cryptography/2014-December/023852.html
[3] https://www.metzdowd.com/pipermail/cryptography/2014-December/023886.html
[4] https://ww1.microchip.com/downloads/en/DeviceDoc/ATSHA204A-Data-Sheet-40002025A.pdf
Fixes: 8006aff155 ("crypto: atmel-sha204a - Set hwrng quality to lowest possible")
Cc: stable@vger.kernel.org
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Use list_first_entry_or_null() to simplify starfive_cryp_find_dev() and
remove the now-unused local variable 'struct starfive_cryp_dev *tmp'.
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Add a new helper omap_sham_unregister_algs() and replace two for loops
in omap_sham_probe() and omap_sham_remove(), which also ensure
->registered is reset to 0.
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Add a new helper omap_des_unregister_algs() and replace two for loops in
omap_des_probe() and omap_des_remove(), which also ensure ->registered
is reset to 0.
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Add a new helper omap_aes_unregister_algs() and replace two for loops in
omap_aes_probe() and omap_aes_remove(), which also ensure ->registered
is reset to 0.
Replace two additional for loops with crypto_engine_unregister_aeads()
while at it and reset ->registered to 0 explicitly.
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Use print_hex_dump_devel() for dumping sensitive key material in
*_setkey() to avoid leaking secrets at runtime when CONFIG_DYNAMIC_DEBUG
is enabled.
Fixes: 8d818c1055 ("crypto: caam/qi2 - add DPAA2-CAAM driver")
Fixes: 226853ac3e ("crypto: caam/qi2 - add skcipher algorithms")
Cc: stable@vger.kernel.org
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Use print_hex_dump_devel() for dumping sensitive key material in
*_setkey() and gen_split_key() to avoid leaking secrets at runtime when
CONFIG_DYNAMIC_DEBUG is enabled.
Fixes: 6e00550319 ("crypto: caam - print debug messages at debug level")
Cc: stable@vger.kernel.org
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The blocking and non-blocking paths were failing to provide valid entropy
due to improper buffer management. Reading the buffer starting from byte 1,
only fetch the 32 bytes of random data from the return message.
Tested on an Atmel SHA204A device.
Before (here for blocking), tests showed repeatedly reading reduced bytes.
$ head -c 32 /dev/hwrng | hexdump -C
00000000 02 28 85 b3 47 40 f2 ee 00 00 00 00 00 00 00 00 |.(..G@..........|
00000010 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000020
After, the result will be similar to the following:
$ head -c 32 /dev/hwrng | hexdump -C
00000000 5a fc 3f 13 14 68 fe 06 68 0a bd 04 83 6e 09 69 |Z.?..h..h....n.i|
00000010 75 ff cf 87 10 84 3b c9 c1 df ae eb 45 53 4c c3 |u.....;.....ESL.|
00000020
Fixes: da001fb651 ("crypto: atmel-i2c - add support for SHA204A random number generator")
Suggested-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Lothar Rubusch <l.rubusch@gmail.com>
Tested-by: Thorsten Blum <thorsten.blum@linux.dev>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Use a flexible array member to combine and simplify allocation.
Move struct mv_cesa_dev down as flexible array members require full
definitions.
Signed-off-by: Rosen Penev <rosenp@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Document glymur compatible for the True Random Number Generator.
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Signed-off-by: Harshal Dev <harshal.dev@oss.qualcomm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
When booted with fips=1, RSA signature generation using SHA-1 must not be
available. However, pkcs1pad(rsa,sha1) can currently be instantiated
because it is not present in alg_test_descs; alg_test() falls through the
no_test path and succeeds, after which the algorithm appears in
/proc/crypto as fips-capable.
Add explicit alg_test_descs entries for pkcs1pad(rsa,sha1) and
pkcs1(rsa,sha1) without marking them fips_allowed, so they are treated as
not FIPS-allowed when fips=1 is enabled.
Include both names to cover kernels where RSA sign/verify is provided via
the pkcs1(...) signature template, while pkcs1pad(...) remains for the
traditional wrapper naming and/or RSAES operations.
Signed-off-by: Jeff Barnes <jeffbarnes@linux.microsoft.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
chainup_buffers() builds a linked list of buffer descriptors for a
scatterlist. If dma_pool_alloc() fails while constructing the list, the
current code sets buf to NULL and later dereferences it unconditionally
at the end of the function:
buf->next = NULL;
buf->phys_next = 0;
This can lead to a null-pointer dereference on allocation failure.
If the failure happens after part of the descriptor chain has already
been allocated and DMA-mapped, the partially constructed chain also
needs to be released.
Fix this by terminating the partially constructed chain on allocation
failure and letting the callers unwind it via their existing cleanup
paths. Also fix ablk_perform() to preserve the hook pointers before
checking for failure, so partially built chains can be freed correctly.
Signed-off-by: Ruoyu Wang <ruoyuw560@gmail.com>
Acked-by: Linus Walleij <linusw@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
While the sun4i-ss and sun8i-ce drivers started selecting CRYPTO_RNG,
the sun8i-ss variant does not, and causes a link failure:
aarch64-linux-ld: drivers/crypto/allwinner/sun8i-ss/sun8i-ss-core.o: in function `sun8i_ss_unregister_algs':
sun8i-ss-core.c:(.text.sun8i_ss_unregister_algs+0x94): undefined reference to `crypto_unregister_rng'
aarch64-linux-ld: drivers/crypto/allwinner/sun8i-ss/sun8i-ss-core.o: in function `sun8i_ss_probe':
sun8i-ss-core.c:(.text.sun8i_ss_probe+0x40c): undefined reference to `crypto_register_rng'
Looking more closely, I see that all of the allwinner crypto drivers have the
same logic where the rng and hash parts of the driver are optional, but then the
generic code is still selected, which is a bit inconsistent, aside from the
missing CRYPTO_RNG select on sun8i-ss.
Change the approach so only the bits that are actually used are built, using
ifdef checks around the optional portions that match the optional references
to the sub-drivers.
Ideally the drivers would get reworked in a way that keeps all the bits
related to the skcipher/ahash/rng codecs in the respective sub-drivers,
rather than having a common driver that knows about all of these.
Fixes: cdadc14359 ("crypto: cryptomgr - Select algorithm types only when CRYPTO_SELFTESTS")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Newer versions of ARM TrustedFirmware-A on MediaTek's ARMv8 SoCs no longer
allow accessing the TRNG from outside of the trusted firmware.
Instead, a vendor-defined custom Secure Monitor Call can be used to
acquire random bytes.
Add support for newer SoCs (MT7981, MT7987, MT7988).
As TF-A for the MT7986 may either follow the old or the new
convention, the best bet is to test if firmware blocks direct access
to the hwrng and if so, expect the SMCC interface to be usable.
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Add compatible strings for MediaTek SoCs where the hardware random number
generator is accessed via a vendor-defined Secure Monitor Call (SMC)
rather than direct MMIO register access:
- mediatek,mt7981-rng
- mediatek,mt7987-rng
- mediatek,mt7988-rng
These variants require no reg, clocks, or clock-names properties since
the RNG hardware is managed by ARM Trusted Firmware-A.
Relax the $nodename pattern to also allow 'rng' in addition to the
existing 'rng@...' pattern.
Add a second example showing the minimal SMC variant binding.
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Use 4 spaces for each level indentation, remove unused label, and add
missing empty line between header include and body.
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The cipher_null crypto_alg cipher is never used in a meaningful way,
given that it is always wrapped in ecb(), which has its own dedicated
implementation. IOW, the cipher_null crypto_alg should never be used to
implement the ecb(cipher_null) skcipher, and using it for other things
is bogus.
However, it is accessible from user space, and due to the nature of the
AF_ALG interface, it may be wrapped in arbitrary ways, exposing issues
in template code that wasn't written with block ciphers with a block
size of '1' in mind.
So drop this code.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This loop is a bit hard to read, with the loop counter that's used in
the HMAC being separate from the actual loop counter, which counts
backwards for some reason. Just replace it with a regular loop.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
A few miscellaneous cleanups to make the code a bit more readable:
- Replace (buf, buflen) with (out, outlen)
- Update (out, outlen) as we go along
- Use size_t for lengths
- Use min()
- Adjust some comments and log messages
- Rename a variable named 'len' to 'err', since it isn't a length
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
We're now incorporating 32 bytes from get_random_bytes() in the
additional input string on every request. The additional input string
is processed with a call to drbg_hmac_update(), which is exactly how the
seed is processed. Thus, in reality this is as good as a reseed.
From the perspective of FIPS 140-3, it isn't as good as a reseed. But
it doesn't actually matter, because from FIPS's point of view
get_random_bytes() provides zero entropy anyway.
Thus, neither the reseed with more get_random_bytes() every 300s, nor
the logic that reseeds more frequently before rng_is_initialized(), is
actually needed anymore. Remove it to simplify the code significantly.
(Technically the use of get_random_bytes() in drbg_seed() itself could
be removed too. But it's safer to keep it there for now.)
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Currently a formal reseed happens only after each 1048576 requests.
That's quite a high number. Let's follow the example of BoringSSL and
use a more conservative value of 4096.
Note that in practice this makes little difference, now that we're
including 32 bytes from get_random_bytes() in the additional input on
every request anyway, which is a de facto reseed.
But for the same reason, we might as well decrease the actual reseed
interval to something more reasonable.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Woodage & Shumow (2018) (https://eprint.iacr.org/2018/349.pdf) showed
that contrary to the claims made by NIST in SP800-90A, HMAC_DRBG doesn't
satisfy the formal definition of forward secrecy (i.e. "backtracking
resistance") when it's called with an empty additional input string.
The actual attack seems pretty benign, as it doesn't actually give the
attacker any previous RNG output, but rather just allows them to test
whether their guess of the previous block of RNG output is correct.
Regardless, it's an annoying design flaw, and it's yet another example
of why NIST's DRBGs aren't all that great.
Meanwhile, the kernel's HMAC_DRBG code also tries to reseed itself
automatically after random.c has reseeded itself. But the
implementation is buggy, as it just checks whether 300 seconds have
elapsed, rather than looking at the actual generation counter.
Let's just follow the example of BoringSSL and use the conservative
approach of always including 32 bytes of "regular" random data in the
additional input string. This fixes both issues described above.
This does reduce performance. But this should be tolerable, since:
- Due to earlier changes, the kernel code that was previously using
drbg.c regardless of FIPS mode is now using it only in FIPS mode.
- The additional input string is processed only once per request. So
if a lot of bytes are generated at once, the cost is amortized.
- The NIST DRBGs are notoriously slow anyway.
Note that this fix should have no impact (either positive or negative)
on FIPS 140 certifiability. From FIPS's point of view the code added by
this commit simply doesn't matter: it adds zero entropy to something
that doesn't need to contain entropy.
Fixes: 541af946fe ("crypto: drbg - SP800-90A Deterministic Random Bit Generator")
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
drbg_kcapi_seed() calls drbg_uninstantiate() only to free drbg->jent and
set drbg->instantiated = false. However, the latter is necessary only
because drbg_kcapi_seed() sets drbg->instantiated = true too early. Fix
that, then just inline the freeing of drbg->jent.
Then, simplify the actual "uninstantiate" in drbg_kcapi_exit(). Just
free drbg->jent (note that this is a no-op on error and null pointers),
then memzero_explicit() the entire drbg_state.
Note that in reality the memzero_explicit() is redundant, since the
crypto_rng API zeroizes the memory anyway. But the way SP800-90A is
worded, it's easy to imagine that someone assessing conformance with it
would be looking for code in drbg.c that says it does an "Uninstantiate"
and does the zeroization. So it's probably worth keeping it somewhat
explicit, even though that means double zeroization in practice.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Fold drbg_prepare_hrng() into its only caller.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Clearly separate the code for the "reseed" and "instantiate" cases,
since what they need to do is quite different.
Note that the mutex guard makes the mutex start being held during the
call to drbg_uninstantiate(), which is fine.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Fold drbg_instantiate() into its only caller.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Put the DRBG implementation of the rng_alg methods in the order in which
they're called (cra_init => set_ent => seed => generate => cra_exit) so
that it's easier to understand the flow.
Also rename drbg_kcapi_random to drbg_kcapi_generate, and
drbg_kcapi_cleanup to drbg_kcapi_exit, so they match the method names.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Simplify drbg_generate_long() to use a more straightforward loop, and
then fold it into its only caller. No functional change.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Use straightforward (buffer, len) parameters instead of struct
drbg_string or lists of strings. This simplifies the code considerably.
For now struct drbg_string is still used in crypto_drbg_ctr_df(), so
move its definition to crypto/df_sp80090a.h.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Currently some of the steps of "Instantiate the DRBG" occur in a
convoluted way in different places in the call stack:
drbg_instantiate()
=> drbg_seed(reseed=0) sets the raw HMAC key drbg_state::C to its
correct initial value, and it sets the state value
drbg_state::V to an *incorrect* initial value.
=> drbg_hmac_update(reseed=0) overwrites drbg_state::V with the
correct initial value, then prepares the hmac_sha512_key
drbg_state::key from the initial raw HMAC key drbg_state::C.
Later, each time the HMAC key is updated, drbg_hmac_update() also uses
drbg_state::C to temporarily store the new raw key.
Simplify all of this by:
- Making drbg_instantiate() set the correct initial values of
drbg_state::V and drbg_state::key.
- Converting drbg_hmac_update() to generate the raw key in a
temporary on-stack array instead of drbg_state::C.
- Removing drbg_state::C.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Move the MODULE_ALIAS_CRYPTO lines in the middle of the file to the end
so that they are in the usual place and next to the other one.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Set rng_alg::seed to different functions for the prediction-resistant
and non-prediction-resistant algorithms, so that the function does not
need to parse the algorithm name to figure out which algorithm it is.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Now that none of the information in struct drbg_core is used, remove it.
The null-ity of the pointer drbg_state::core was used to keep track of
whether the DRBG has been instantiated. Replace it with a boolean.
No functional change.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Since the HMAC algorithm is now fixed at HMAC-SHA512, just use the
HMAC-SHA512 library API. This is simpler and more efficient.
Remove error-handling code that is no longer needed.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Now that the sizes of V and C are known at compile time, embed them into
struct drbg_state rather than using separate allocations.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Since only one drbg_core remains, the state length, block length, and
security strength are now fixed values. Moreover, the maximum request
length, maximum additional data length, and maximum number of requests
were all already fixed values.
Simplify the code by just using #defines for all these fixed values.
In drbg_seed_from_random(), take advantage of the constant to define the
array size. Remove assertions that are no longer useful.
In the case of drbg_blocklen() and drbg_statelen(), replace these with a
single value DRBG_STATE_LEN, as for HMAC_DRBG they are the same thing.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Now that there's only one set of state operations, use direct calls to
those operations.
No change in behavior. In particular, drbg_alloc_state() doesn't change
behavior, because the only remaining drbg_core uses HMAC_DRBG.
drbg_uninstantiate() doesn't change behavior, because a NULL d_ops
implied NULL priv_data which makes a drbg_fini_hash_kernel() a no-op.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Now that "drbg_pr_hmac_sha512" and "drbg_nopr_hmac_sha512" are the only
crypto_rng algorithms left in crypto/drbg.c, simplify the algorithm
registration logic to register these more directly without relying on
the drbg_cores[] array (which will be removed).
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Remove support for the HMAC-SHA256 and HMAC-SHA384 variants of
HMAC_DRBG, leaving only the HMAC-SHA512 variant of HMAC_DRBG.
HMAC-SHA512 is already the default. The default did used to be
HMAC-SHA256, but several years ago it was upgraded to HMAC-SHA512 "to
support compliance with SP800-90B and SP800-90C". Given that the point
of crypto/drbg.c is compliance with those standards, and there's also no
technical reason to prefer HMAC-SHA384 in this situation even if
acceptable, there's really no point in offering anything else.
Note: now that only HMAC-SHA512 remains, a lot of unnecessary
abstractions can be removed. A later commit will do that. This commit
just straightforwardly removes the HMAC-SHA256 and HMAC-SHA384 code.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Synchronize the drbg_nopr_hmac_sha512 test vector with the first test
vector from the latest ACVP json files, so that both of the DRBG test
vectors are pulled from a consistent source.
Note that the new test vector has a nonempty personalization string.
That should be helpful as well: Some FIPS labs require this, due to
their interpretation of SP800-90A 11.3.2 which says that a
"representative" value of the personalization string must be tested.
It also now does an explicit reseed, which makes it clearer that the
requirement to test "Reseed" is met, without having to interpret the
additional input processing as covering that.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Add a test for drbg_pr_hmac_sha512, which previously didn't have a test.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Now that the menuconfig CRYPTO_DRBG_MENU has no options in it other than
the hidden symbol CRYPTO_DRBG, remove it and move CRYPTO_DRBG to its
parent menu. Give CRYPTO_DRBG an appropriate prompt and help text.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Remove the support for HASH_DRBG. It's likely unused code, seeing as
HMAC_DRBG is always enabled and prioritized over it unless
NETLINK_CRYPTO is used to change the algorithm priorities.
There's also no compelling reason to support more than one of
[HMAC_DRBG, HASH_DRBG, CTR_DRBG]. By definition, callers cannot tell
any difference in their outputs. And all are FIPS-certifiable, which is
the only point of the kernel's NIST DRBGs anyway.
Switching to HASH_DRBG doesn't seem all that compelling, either. For
one, it's more complex than HMAC_DRBG.
Thus, let's just drop HASH_DRBG support and focus on HMAC_DRBG.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> # m68k
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Remove the support for CTR_DRBG. It's likely unused code, seeing as
HMAC_DRBG is always enabled and prioritized over it unless
NETLINK_CRYPTO is used to change the algorithm priorities.
There's also no compelling reason to support more than one of
[HMAC_DRBG, HASH_DRBG, CTR_DRBG]. By definition, callers cannot tell
any difference in their outputs. And all are FIPS-certifiable, which is
the only point of the kernel's NIST DRBGs anyway.
Switching to CTR_DRBG doesn't seem all that compelling, either. While
it's often the fastest NIST DRBG, it has several disadvantages:
- CTR_DRBG uses AES. Some platforms don't have AES acceleration at all,
causing a fallback to the table-based AES code which is very slow and
can be vulnerable to cache-timing attacks. In contrast, HMAC_DRBG
uses primitives that are consistently constant-time.
- CTR_DRBG is usually considered to be somewhat less cryptographically
robust than HMAC_DRBG. Granted, HMAC_DRBG isn't all that great
either, e.g. given the negative result from Woodage & Shumow (2018)
(https://eprint.iacr.org/2018/349.pdf), but that can be worked around.
- CTR_DRBG is more complex than HMAC_DRBG, risking bugs. Indeed, while
reviewing the CTR_DRBG code, I found two bugs, including one where it
can return success while leaving the output buffer uninitialized.
- The kernel's implementation of CTR_DRBG uses an "ctr(aes)"
crypto_skcipher and relies on it returning the next counter value.
That's fragile, and indeed historically many "ctr(aes)"
crypto_skcipher implementations haven't done that. E.g. see
commit 511306b2d0 ("crypto: arm/aes-ce - update IV after partial final CTR block"),
commit fa5fd3afc7 ("crypto: arm64/aes-blk - update IV after partial final CTR block"),
commit 371731ec21 ("crypto: atmel-aes - Fix saving of IV for CTR mode"),
commit 25baaf8e2c ("crypto: crypto4xx - fix ctr-aes missing output IV"),
commit 334d37c9e2 ("crypto: caam - update IV using HW support"),
commit 0a4491d3fe ("crypto: chelsio - count incomplete block in IV"),
commit e8e3c1ca57 ("crypto: s5p - update iv after AES-CBC op end").
I.e., there were many years where the kernel's CTR_DRBG code (if it
were to have actually been used) repeated outputs on some platforms.
AES-CTR also uses a 128-bit counter, which creates overflow edge cases
that are sometimes gotten wrong. E.g. see commit 009b30ac74
("crypto: vmx - CTR: always increment IV as quadword").
So, while switching to CTR_DRBG for performance reasons isn't completely
out of the question (notably BoringSSL uses it), it would take quite a
bit more work to create a solid implementation of it in the kernel,
including a more solid implementation of AES-CTR itself (in lib/crypto/,
with a scalar bit-sliced fallback, etc). Since HMAC_DRBG has always
been the default NIST DRBG variant in the kernel and is in a better
state, let's just standardize on it for now.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> # m68k
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The inclusion of <crypto/internal/cipher.h> and the import of the
internal crypto namespace became unnecessary in commit ba0570bdf1
("crypto: drbg - Replace AES cipher calls with library calls").
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
include/crypto/drbg.h no longer contains anything that is used
externally to crypto/drbg.c. Therefore, fold it into crypto/drbg.c.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
FIPS 140-2 required that a continuous test for repeated outputs be done
on both "Approved RNGs" and "Non-Approved RNGs".
That's apparently why crypto/drbg.c does such a test on the bytes it
pulls from get_random_bytes(), despite get_random_bytes() being a
"Non-Approved RNG" that is credited with zero entropy for FIPS purposes.
(From FIPS's point of view, the "Approved RNG" is jitterentropy.)
FIPS 140-3 "modernized" the continuous RNG test requirements. They're
now a bit more sophisticated, requiring both an "Adaptive Proportion
Test" and a "Repetition Count Test".
At the same time, FIPS 140-3 doesn't require continuous RNG tests on
"Non-Approved RNGs" if a "vetted conditioning component" is used. The
SP800-90A DRBGs are exactly such a vetted conditioning component, by
their design. (In the case of HASH_DRBG and CTR_DRBG, the derivation
function does have to be implemented. But the kernel does that.)
In other words: from FIPS 140-3's point of view, get_random_bytes()
still produces zero entropy, but the way the DRBG combines those bytes
with the jitterentropy bytes preserves all the "approved" entropy from
jitterentropy. Thus no test for get_random_bytes() is required.
Seeing as FIPS 140-2 certificates stopped being issued in 2021 in favor
of FIPS 140-3, this means this code is obsolete. Remove it.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Fold the contents of the inline functions crypto_drbg_get_bytes_addtl(),
crypto_drbg_get_bytes_addtl_test(), and crypto_drbg_reset_test() into
their only caller in drbg_cavs_test(). It ends up being much simpler.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commented-out code doesn't compile. Even if it did, it wouldn't
actually do what it was apparently intended to do, seeing as the "test"
for "drbg_pr_hmac_sha512" and "drbg_pr_ctr_aes256" is alg_test_null().
Just delete it to avoid keeping broken code around, and so that there
isn't any perceived need to try to update it as the DRBG code is
refactored.
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
