[EXTERNAL] [PATCH RFC 1/8] certs: Introduce ability to link to a system key

[Bharat Bhushan]

> -----Original Message-----
> From: Eric Snowberg <eric.snowberg at oracle.com>
> Sent: Monday, March 11, 2024 9:41 PM
> To: linux-security-module at vger.kernel.org
> Cc: dhowells at redhat.com; dwmw2 at infradead.org;
> herbert at gondor.apana.org.au; davem at davemloft.net; ardb at kernel.org;
> jarkko at kernel.org; paul at paul-moore.com; jmorris at namei.org;
> serge at hallyn.com; zohar at linux.ibm.com; roberto.sassu at huawei.com;
> dmitry.kasatkin at gmail.com; mic at digikod.net; casey at schaufler-ca.com;
> stefanb at linux.ibm.com; eric.snowberg at oracle.com; linux-
> kernel at vger.kernel.org; keyrings at vger.kernel.org; linux-
> crypto at vger.kernel.org; linux-efi at vger.kernel.org; linux-
> integrity at vger.kernel.org
> Subject: [EXTERNAL] [PATCH RFC 1/8] certs: Introduce ability to link to a
> system key
> 
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> before clicking links or opening attachments
> 
> ----------------------------------------------------------------------
> Introduce a new function to allow a keyring to link to a key contained
> within one of the system keyrings (builtin, secondary, or platform).
> Depending on how the kernel is built, if the machine keyring is
> available, it will be checked as well, since it is linked to the secondary
> keyring. If the asymmetric key id matches a key within one of these
> system keyrings, the matching key is linked into the passed in
> keyring.
> 
> Signed-off-by: Eric Snowberg <eric.snowberg at oracle.com>
> ---
>  certs/system_keyring.c        | 29 +++++++++++++++++++++++++++++
>  include/keys/system_keyring.h |  7 ++++++-
>  2 files changed, 35 insertions(+), 1 deletion(-)
> 
> diff --git a/certs/system_keyring.c b/certs/system_keyring.c
> index 9de610bf1f4b..b647be49f6e0 100644
> --- a/certs/system_keyring.c
> +++ b/certs/system_keyring.c
> @@ -426,3 +426,32 @@ void __init set_platform_trusted_keys(struct key
> *keyring)
>  	platform_trusted_keys = keyring;
>  }
>  #endif
> +
> +/**
> + * system_key_link - Link to a system key
> + * @keyring: The keyring to link into
> + * @id: The asymmetric key id to look for in the system keyring
> + */
> +int system_key_link(struct key *keyring, struct asymmetric_key_id *id)
> +{
> +	struct key *tkey;
> +
> +#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
> +	tkey = find_asymmetric_key(secondary_trusted_keys, id, NULL, NULL,
> false);
> +#else
> +	tkey = find_asymmetric_key(builtin_trusted_keys, id, NULL, NULL,
> false);
> +#endif
> +	if (!IS_ERR(tkey))
> +		goto found;
> +
> +	tkey = find_asymmetric_key(platform_trusted_keys, id, NULL, NULL,
> false);
> +
> +	if (!IS_ERR(tkey))
> +		goto found;
> +
> +	return -1;

Please use -ENOKEY.

Thanks
-Bharat

> +
> +found:
> +	key_link(keyring, tkey);
> +	return 0;
> +}
> diff --git a/include/keys/system_keyring.h b/include/keys/system_keyring.h
> index 8365adf842ef..b47ac8e2001a 100644
> --- a/include/keys/system_keyring.h
> +++ b/include/keys/system_keyring.h
> @@ -9,6 +9,7 @@
>  #define _KEYS_SYSTEM_KEYRING_H
> 
>  #include <linux/key.h>
> +struct asymmetric_key_id;
> 
>  enum blacklist_hash_type {
>  	/* TBSCertificate hash */
> @@ -28,7 +29,7 @@ int restrict_link_by_digsig_builtin(struct key
> *dest_keyring,
>  				    const union key_payload *payload,
>  				    struct key *restriction_key);
>  extern __init int load_module_cert(struct key *keyring);
> -
> +extern int system_key_link(struct key *keyring, struct asymmetric_key_id
> *id);
>  #else
>  #define restrict_link_by_builtin_trusted restrict_link_reject
>  #define restrict_link_by_digsig_builtin restrict_link_reject
> @@ -38,6 +39,10 @@ static inline __init int load_module_cert(struct key
> *keyring)
>  	return 0;
>  }
> 
> +static inline int system_key_link(struct key *keyring, struct asymmetric_key_id
> *id)
> +{
> +	return 0;
> +}
>  #endif
> 
>  #ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
> --
> 2.39.3
>