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Message-ID: <07e8055e-2871-f8ac-a125-19046c6390c7@linux.ibm.com>
Date: Fri, 2 Apr 2021 07:29:03 -0400
From: Stefan Berger <stefanb@...ux.ibm.com>
To: Nayna Jain <nayna@...ux.ibm.com>, linux-integrity@...r.kernel.org,
keyrings@...r.kernel.org
Cc: linux-security-module@...r.kernel.org,
David Howells <dhowells@...hat.com>,
Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
Mimi Zohar <zohar@...ux.ibm.com>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
David Woodhouse <dwmw2@...radead.org>
Subject: Re: [PATCH v3 3/3] ima: enable loading of build time generated key on
.ima keyring
On 3/30/21 9:16 AM, Nayna Jain wrote:
> The kernel currently only loads the kernel module signing key onto the
> builtin trusted keyring. Load the module signing key onto the IMA keyring
> as well.
>
> Signed-off-by: Nayna Jain <nayna@...ux.ibm.com>
Acked-by: Stefan Berger <stefanb@...ux.ibm.com>
> ---
> certs/system_certificates.S | 13 +++++++++-
> certs/system_keyring.c | 47 +++++++++++++++++++++++++++--------
> include/keys/system_keyring.h | 7 ++++++
> security/integrity/digsig.c | 2 ++
> 4 files changed, 58 insertions(+), 11 deletions(-)
>
> diff --git a/certs/system_certificates.S b/certs/system_certificates.S
> index 8f29058adf93..dcad27ea8527 100644
> --- a/certs/system_certificates.S
> +++ b/certs/system_certificates.S
> @@ -8,9 +8,11 @@
> .globl system_certificate_list
> system_certificate_list:
> __cert_list_start:
> -#ifdef CONFIG_MODULE_SIG
> +__module_cert_start:
> +#if defined(CONFIG_MODULE_SIG) || defined(CONFIG_IMA_APPRAISE_MODSIG)
> .incbin "certs/signing_key.x509"
> #endif
> +__module_cert_end:
> .incbin "certs/x509_certificate_list"
> __cert_list_end:
>
> @@ -35,3 +37,12 @@ system_certificate_list_size:
> #else
> .long __cert_list_end - __cert_list_start
> #endif
> +
> + .align 8
> + .globl module_cert_size
> +module_cert_size:
> +#ifdef CONFIG_64BIT
> + .quad __module_cert_end - __module_cert_start
> +#else
> + .long __module_cert_end - __module_cert_start
> +#endif
> diff --git a/certs/system_keyring.c b/certs/system_keyring.c
> index 4b693da488f1..bb122bf4cc17 100644
> --- a/certs/system_keyring.c
> +++ b/certs/system_keyring.c
> @@ -27,6 +27,7 @@ static struct key *platform_trusted_keys;
>
> extern __initconst const u8 system_certificate_list[];
> extern __initconst const unsigned long system_certificate_list_size;
> +extern __initconst const unsigned long module_cert_size;
>
> /**
> * restrict_link_to_builtin_trusted - Restrict keyring addition by built in CA
> @@ -132,19 +133,11 @@ static __init int system_trusted_keyring_init(void)
> */
> device_initcall(system_trusted_keyring_init);
>
> -/*
> - * Load the compiled-in list of X.509 certificates.
> - */
> -static __init int load_system_certificate_list(void)
> +static __init int load_cert(const u8 *p, const u8 *end, struct key *keyring)
> {
> key_ref_t key;
> - const u8 *p, *end;
> size_t plen;
>
> - pr_notice("Loading compiled-in X.509 certificates\n");
> -
> - p = system_certificate_list;
> - end = p + system_certificate_list_size;
> while (p < end) {
> /* Each cert begins with an ASN.1 SEQUENCE tag and must be more
> * than 256 bytes in size.
> @@ -159,7 +152,7 @@ static __init int load_system_certificate_list(void)
> if (plen > end - p)
> goto dodgy_cert;
>
> - key = key_create_or_update(make_key_ref(builtin_trusted_keys, 1),
> + key = key_create_or_update(make_key_ref(keyring, 1),
> "asymmetric",
> NULL,
> p,
> @@ -186,6 +179,40 @@ static __init int load_system_certificate_list(void)
> pr_err("Problem parsing in-kernel X.509 certificate list\n");
> return 0;
> }
> +
> +__init int load_module_cert(struct key *keyring)
> +{
> + const u8 *p, *end;
> +
> + if (!IS_ENABLED(CONFIG_IMA_APPRAISE_MODSIG))
> + return 0;
> +
> + pr_notice("Loading compiled-in module X.509 certificates\n");
> +
> + p = system_certificate_list;
> + end = p + module_cert_size;
> +
> + return load_cert(p, end, keyring);
> +}
> +
> +/*
> + * Load the compiled-in list of X.509 certificates.
> + */
> +static __init int load_system_certificate_list(void)
> +{
> + const u8 *p, *end;
> +
> + pr_notice("Loading compiled-in X.509 certificates\n");
> +
> +#ifdef CONFIG_MODULE_SIG
> + p = system_certificate_list;
> +#else
> + p = system_certificate_list + module_cert_size;
> +#endif
> +
> + end = p + system_certificate_list_size;
> + return load_cert(p, end, builtin_trusted_keys);
> +}
> late_initcall(load_system_certificate_list);
>
> #ifdef CONFIG_SYSTEM_DATA_VERIFICATION
> diff --git a/include/keys/system_keyring.h b/include/keys/system_keyring.h
> index fb8b07daa9d1..f954276c616a 100644
> --- a/include/keys/system_keyring.h
> +++ b/include/keys/system_keyring.h
> @@ -16,9 +16,16 @@ extern int restrict_link_by_builtin_trusted(struct key *keyring,
> const struct key_type *type,
> const union key_payload *payload,
> struct key *restriction_key);
> +extern __init int load_module_cert(struct key *keyring);
>
> #else
> #define restrict_link_by_builtin_trusted restrict_link_reject
> +
> +static inline __init int load_module_cert(struct key *keyring)
> +{
> + return 0;
> +}
> +
> #endif
>
> #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
> diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c
> index 250fb0836156..3b06a01bd0fd 100644
> --- a/security/integrity/digsig.c
> +++ b/security/integrity/digsig.c
> @@ -111,6 +111,8 @@ static int __init __integrity_init_keyring(const unsigned int id,
> } else {
> if (id == INTEGRITY_KEYRING_PLATFORM)
> set_platform_trusted_keys(keyring[id]);
> + if (id == INTEGRITY_KEYRING_IMA)
> + load_module_cert(keyring[id]);
> }
>
> return err;
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