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Message-ID: <804e0075-e435-f60b-e0a7-a9b48a76ce72@linux.ibm.com>
Date: Thu, 11 Feb 2021 17:32:10 -0500
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>
Subject: Re: [PATCH 5/5] ima: enable loading of build time generated key to
.ima keyring
On 2/11/21 2:54 PM, Nayna Jain wrote:
> The kernel currently only loads the kernel module signing key onto
> the builtin trusted keyring. To support IMA, load the module signing
> key selectively either onto builtin or ima keyring based on MODULE_SIG
> or MODULE_APPRAISE_MODSIG config respectively; and loads the CA kernel
> key onto builtin trusted keyring.
>
> Signed-off-by: Nayna Jain <nayna@...ux.ibm.com>
> ---
> certs/system_keyring.c | 56 +++++++++++++++++++++++++++--------
> include/keys/system_keyring.h | 9 +++++-
> security/integrity/digsig.c | 4 +++
> 3 files changed, 55 insertions(+), 14 deletions(-)
>
> diff --git a/certs/system_keyring.c b/certs/system_keyring.c
> index 798291177186..0bbbe501f8a7 100644
> --- a/certs/system_keyring.c
> +++ b/certs/system_keyring.c
> @@ -26,6 +26,7 @@ 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
> @@ -131,19 +132,12 @@ 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,
> + unsigned long flags)
> {
> 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.
> @@ -158,16 +152,15 @@ 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,
> plen,
> ((KEY_POS_ALL & ~KEY_POS_SETATTR) |
> KEY_USR_VIEW | KEY_USR_READ),
> - KEY_ALLOC_NOT_IN_QUOTA |
> - KEY_ALLOC_BUILT_IN |
> - KEY_ALLOC_BYPASS_RESTRICTION);
> + flags);
> +
> if (IS_ERR(key)) {
> pr_err("Problem loading in-kernel X.509 certificate (%ld)\n",
> PTR_ERR(key));
> @@ -185,6 +178,43 @@ 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, unsigned long flags)
> +{
> + 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;
> + load_cert(p, end, keyring, flags);
> +
> + return 0;
See my comment below.
> +}
> +
> +/*
> + * 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;
> + load_cert(p, end, builtin_trusted_keys, KEY_ALLOC_NOT_IN_QUOTA |
> + KEY_ALLOC_BUILT_IN |
> + KEY_ALLOC_BYPASS_RESTRICTION);
> + return 0;
The old load_system_certificate_list always returned 0 and the new
load_cert also does. You could just do 'return load_cert(p, ...)' here
and still get the 0.
> +}
> 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..e91c03376599 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, unsigned long flags);
> #else
> #define restrict_link_by_builtin_trusted restrict_link_reject
> +
> +static inline __init int load_module_cert(struct key *keyring,
> + unsigned long flags)
> +{
> + return 0;
> +}
> +
> #endif
>
> #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
> diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c
> index 0f518dcfde05..4009d1e33fe0 100644
> --- a/security/integrity/digsig.c
> +++ b/security/integrity/digsig.c
> @@ -111,8 +111,12 @@ 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], KEY_ALLOC_NOT_IN_QUOTA);
> }
>
> + pr_info("Loading key to ima keyring\n");
> +
> return err;
> }
>
Otherwise lgtm.
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