From: Ahmad Fatoum <a.fatoum@pengutronix.de>
To: Mimi Zohar <zohar@linux.ibm.com>,
James Bottomley <jejb@linux.ibm.com>,
Jarkko Sakkinen <jarkko@kernel.org>,
David Howells <dhowells@redhat.com>
Cc: kernel@pengutronix.de, "Sumit Garg" <sumit.garg@linaro.org>,
"Pankaj Gupta" <pankaj.gupta@nxp.com>,
"David Gstir" <david@sigma-star.at>,
"Michael Walle" <michael@walle.cc>,
"John Ernberg" <john.ernberg@actia.se>,
"James Morris" <jmorris@namei.org>,
"Serge E. Hallyn" <serge@hallyn.com>,
"Horia Geantă" <horia.geanta@nxp.com>,
"Herbert Xu" <herbert@gondor.apana.org.au>,
"David S. Miller" <davem@davemloft.net>,
"Jan Luebbe" <j.luebbe@pengutronix.de>,
"Eric Biggers" <ebiggers@kernel.org>,
"Richard Weinberger" <richard@nod.at>,
"Franck LENORMAND" <franck.lenormand@nxp.com>,
"Matthias Schiffer" <matthias.schiffer@ew.tq-group.com>,
keyrings@vger.kernel.org, linux-crypto@vger.kernel.org,
linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-security-module@vger.kernel.org,
"Theodore Ts'o" <tytso@mit.edu>,
"Jason A. Donenfeld" <Jason@zx2c4.com>
Subject: Re: [PATCH v10 2/7] KEYS: trusted: allow use of kernel RNG for key material
Date: Tue, 17 May 2022 18:25:08 +0200 [thread overview]
Message-ID: <6da32ccf-1735-c47f-02c3-f7a8c736dbe3@pengutronix.de> (raw)
In-Reply-To: <1c6a5ce2564c29a06eca255072a379351a5fc026.camel@linux.ibm.com>
Hello Mimi,
[Cc'ing RNG maintainers in case they want to chime in]
On 17.05.22 17:52, Mimi Zohar wrote:
> On Fri, 2022-05-13 at 16:57 +0200, Ahmad Fatoum wrote:
>> static int __init init_trusted(void)
>> {
>> + int (*get_random)(unsigned char *key, size_t key_len);
>> int i, ret = 0;
>>
>> for (i = 0; i < ARRAY_SIZE(trusted_key_sources); i++) {
>> @@ -322,6 +333,28 @@ static int __init init_trusted(void)
>> strlen(trusted_key_sources[i].name)))
>> continue;
>>
>> + /*
>> + * We always support trusted.rng="kernel" and "default" as
>> + * well as trusted.rng=$trusted.source if the trust source
>> + * defines its own get_random callback.
>> + */
>
> While TEE trusted keys support was upstreamed, there was a lot of
> discussion about using kernel RNG. One of the concerns was lack of or
> insuffiencent entropy during early boot on embedded devices. This
> concern needs to be clearly documented in both Documentation/admin-
> guide/kernel-parameters.txt and Documentation/security/keys/trusted-
> encrypted.rst.
If a user decides to use kernel RNG for trusted keys, wait_for_random_bytes()
called first thing in the used get_random_bytes_wait() will (quoting
documentation) "wait for the input pool to be seeded and thus [is] guaranteed
to supply cryptographically secure random numbers."
Does this address your concerns about Kernel RNG use?
Thanks,
Ahmad
>
> thanks,
>
> Mimi
>
>> + get_random = trusted_key_sources[i].ops->get_random;
>> + if (trusted_rng && strcmp(trusted_rng, "default")) {
>> + if (!strcmp(trusted_rng, "kernel")) {
>> + get_random = kernel_get_random;
>> + } else if (strcmp(trusted_rng, trusted_key_sources[i].name) ||
>> + !get_random) {
>> + pr_warn("Unsupported RNG. Supported: kernel");
>> + if (get_random)
>> + pr_cont(", %s", trusted_key_sources[i].name);
>> + pr_cont(", default\n");
>> + return -EINVAL;
>> + }
>> + }
>> +
>> + if (!get_random)
>> + get_random = kernel_get_random;
>> +
>> static_call_update(trusted_key_init,
>> trusted_key_sources[i].ops->init);
>
>
--
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next prev parent reply other threads:[~2022-05-17 16:25 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-13 14:56 [PATCH v10 0/7] KEYS: trusted: Introduce support for NXP CAAM-based trusted keys Ahmad Fatoum
2022-05-13 14:56 ` [PATCH v10 1/7] KEYS: trusted: allow use of TEE as backend without TCG_TPM support Ahmad Fatoum
2022-05-13 14:57 ` [PATCH v10 2/7] KEYS: trusted: allow use of kernel RNG for key material Ahmad Fatoum
2022-05-17 15:52 ` Mimi Zohar
2022-05-17 16:25 ` Ahmad Fatoum [this message]
2022-05-17 17:40 ` Jason A. Donenfeld
2022-05-17 17:38 ` Jason A. Donenfeld
2022-05-17 18:21 ` Mimi Zohar
2022-05-17 18:30 ` Jason A. Donenfeld
2022-05-17 19:49 ` Mimi Zohar
2022-05-18 4:31 ` Ahmad Fatoum
2022-05-17 17:27 ` Jason A. Donenfeld
2022-05-17 17:52 ` Ahmad Fatoum
2022-05-17 18:00 ` Jason A. Donenfeld
2022-05-17 18:27 ` Ahmad Fatoum
2022-05-17 18:10 ` Jarkko Sakkinen
2022-05-17 18:20 ` Ahmad Fatoum
2022-05-17 18:20 ` Jason A. Donenfeld
2022-05-13 14:57 ` [PATCH v10 3/7] crypto: caam - determine whether CAAM supports blob encap/decap Ahmad Fatoum
2022-05-17 10:03 ` [EXT] " Pankaj Gupta
2022-05-13 14:57 ` [PATCH v10 4/7] crypto: caam - add in-kernel interface for blob generator Ahmad Fatoum
2022-05-13 14:57 ` [PATCH v10 5/7] KEYS: trusted: Introduce support for NXP CAAM-based trusted keys Ahmad Fatoum
2022-05-13 14:57 ` [PATCH v10 6/7] doc: trusted-encrypted: describe new CAAM trust source Ahmad Fatoum
2022-05-13 14:57 ` [PATCH v10 7/7] MAINTAINERS: add KEYS-TRUSTED-CAAM Ahmad Fatoum
2022-05-16 18:36 ` [PATCH v10 0/7] KEYS: trusted: Introduce support for NXP CAAM-based trusted keys Jarkko Sakkinen
2022-05-17 12:44 ` Ahmad Fatoum
2022-05-18 1:08 ` Jarkko Sakkinen
2022-05-18 4:36 ` Ahmad Fatoum
2022-05-18 14:58 ` Jarkko Sakkinen
2022-05-19 23:41 ` Jarkko Sakkinen
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