Re: [PATCH v3 6/6] integrity: PowerVM support for loading third party code signing keys

["Jarkko Sakkinen" <jarkko@kernel.org>]

On Sun Aug 13, 2023 at 5:15 AM EEST, Nayna Jain wrote:
> On secure boot enabled PowerVM LPAR, third party code signing keys are
> needed during early boot to verify signed third party modules. These
> third party keys are stored in moduledb object in the Platform
> KeyStore(PKS).
>
> Load third party code signing keys onto .secondary_trusted_keys keyring.
>
> Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
> ---
>  certs/system_keyring.c                        | 30 +++++++++++++++++++
>  include/keys/system_keyring.h                 |  7 +++++
>  security/integrity/integrity.h                |  1 +
>  .../platform_certs/keyring_handler.c          |  8 +++++
>  .../platform_certs/keyring_handler.h          |  5 ++++
>  .../integrity/platform_certs/load_powerpc.c   | 18 ++++++++++-
>  6 files changed, 68 insertions(+), 1 deletion(-)
>
> diff --git a/certs/system_keyring.c b/certs/system_keyring.c
> index b348e0898d34..e458d414918d 100644
> --- a/certs/system_keyring.c
> +++ b/certs/system_keyring.c
> @@ -396,3 +396,33 @@ void __init set_platform_trusted_keys(struct key *keyring)
>  	platform_trusted_keys = keyring;
>  }
>  #endif
> +
> +/**
> + * add_to_secondary_keyring - Add to secondary keyring.
> + * @source: Source of key
> + * @data: The blob holding the key
> + * @len: The length of the data blob
> + *
> + * Add a key to the secondary keyring. The key must be vouched for by a key in the builtin,
> + * machine or secondary keyring itself.
> + */
> +void __init add_to_secondary_keyring(const char *source, const void *data, size_t len)
> +{
> +	key_ref_t key;
> +	key_perm_t perm;
> +
> +	perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_VIEW;
> +
> +	key = key_create_or_update(make_key_ref(secondary_trusted_keys, 1),
> +				   "asymmetric",
> +				   NULL, data, len, perm,
> +				   KEY_ALLOC_NOT_IN_QUOTA);
> +	if (IS_ERR(key)) {
> +		pr_err("Problem loading X.509 certificate from %s to secondary keyring %ld\n",
> +		       source, PTR_ERR(key));
> +		return;
> +	}
> +
> +	pr_notice("Loaded X.509 cert '%s'\n", key_ref_to_ptr(key)->description);
> +	key_ref_put(key);
> +}
> diff --git a/include/keys/system_keyring.h b/include/keys/system_keyring.h
> index 7e2583208820..4188f75d1bac 100644
> --- a/include/keys/system_keyring.h
> +++ b/include/keys/system_keyring.h
> @@ -50,9 +50,16 @@ int restrict_link_by_digsig_builtin_and_secondary(struct key *keyring,
>  						  const struct key_type *type,
>  						  const union key_payload *payload,
>  						  struct key *restriction_key);
> +void __init add_to_secondary_keyring(const char *source, const void *data,
> +				     size_t len);
> +
>  #else
>  #define restrict_link_by_builtin_and_secondary_trusted restrict_link_by_builtin_trusted
>  #define restrict_link_by_digsig_builtin_and_secondary restrict_link_by_digsig_builtin
> +void __init add_to_secondary_keyring(const char *source, const void *data,
> +				     size_t len)
> +{
> +}
>  #endif
>  
>  #ifdef CONFIG_INTEGRITY_MACHINE_KEYRING
> diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h
> index d7553c93f5c0..efaa2eb789ad 100644
> --- a/security/integrity/integrity.h
> +++ b/security/integrity/integrity.h
> @@ -228,6 +228,7 @@ static inline int __init integrity_load_cert(const unsigned int id,
>  {
>  	return 0;
>  }
> +
>  #endif /* CONFIG_INTEGRITY_SIGNATURE */
>  
>  #ifdef CONFIG_INTEGRITY_ASYMMETRIC_KEYS
> diff --git a/security/integrity/platform_certs/keyring_handler.c b/security/integrity/platform_certs/keyring_handler.c
> index 586027b9a3f5..13ea17207902 100644
> --- a/security/integrity/platform_certs/keyring_handler.c
> +++ b/security/integrity/platform_certs/keyring_handler.c
> @@ -78,6 +78,14 @@ __init efi_element_handler_t get_handler_for_ca_keys(const efi_guid_t *sig_type)
>  	return NULL;
>  }
>  
> +__init efi_element_handler_t get_handler_for_code_signing_keys(const efi_guid_t *sig_type)
> +{
> +	if (efi_guidcmp(*sig_type, efi_cert_x509_guid) == 0)
> +		return add_to_secondary_keyring;
> +
> +	return NULL;
> +}
> +
>  /*
>   * Return the appropriate handler for particular signature list types found in
>   * the UEFI dbx and MokListXRT tables.
> diff --git a/security/integrity/platform_certs/keyring_handler.h b/security/integrity/platform_certs/keyring_handler.h
> index 6f15bb4cc8dc..f92895cc50f6 100644
> --- a/security/integrity/platform_certs/keyring_handler.h
> +++ b/security/integrity/platform_certs/keyring_handler.h
> @@ -34,6 +34,11 @@ efi_element_handler_t get_handler_for_mok(const efi_guid_t *sig_type);
>   */
>  efi_element_handler_t get_handler_for_ca_keys(const efi_guid_t *sig_type);
>  
> +/*
> + * Return the handler for particular signature list types for code signing keys.
> + */
> +efi_element_handler_t get_handler_for_code_signing_keys(const efi_guid_t *sig_type);
> +
>  /*
>   * Return the handler for particular signature list types found in the dbx.
>   */
> diff --git a/security/integrity/platform_certs/load_powerpc.c b/security/integrity/platform_certs/load_powerpc.c
> index 6263ce3b3f1e..32c4e5fbf0fb 100644
> --- a/security/integrity/platform_certs/load_powerpc.c
> +++ b/security/integrity/platform_certs/load_powerpc.c
> @@ -59,7 +59,7 @@ static __init void *get_cert_list(u8 *key, unsigned long keylen, u64 *size)
>  static int __init load_powerpc_certs(void)
>  {
>  	void *db = NULL, *dbx = NULL, *data = NULL;
> -	void *trustedca = NULL;
> +	void *trustedca = NULL, *moduledb = NULL;

The patch looks otherwise good but I'm not sure about this initialization.

>  	u64 dsize = 0;
>  	u64 offset = 0;
>  	int rc = 0;
> @@ -137,6 +137,22 @@ static int __init load_powerpc_certs(void)
>  		kfree(data);
>  	}
>  
> +	data = get_cert_list("moduledb", 9,  &dsize);
> +	if (!data) {
> +		pr_info("Couldn't get moduledb list from firmware\n");
> +	} else if (IS_ERR(data)) {
> +		rc = PTR_ERR(data);
> +		pr_err("Error reading moduledb from firmware: %d\n", rc);
> +	} else {
> +		extract_esl(moduledb, data, dsize, offset);
> +
> +		rc = parse_efi_signature_list("powerpc:moduledb", moduledb, dsize,
> +					      get_handler_for_code_signing_keys);
> +		if (rc)
> +			pr_err("Couldn't parse moduledb signatures: %d\n", rc);
> +		kfree(data);
> +	}
> +
>  	return rc;
>  }
>  late_initcall(load_powerpc_certs);
> -- 
> 2.31.1

BR, Jarkko