Re: [PATCH v7 11/17] KEYS: Introduce link restriction for machine keys

Mimi Zohar
2021-11-19T00:20:38Z

Hi Eric,

On Mon, 2021-11-15 at 19:15 -0500, Eric Snowberg wrote:
> Introduce a new link restriction that includes the trusted builtin,
> secondary and machine keys. The restriction is based on the key to be
> added being vouched for by a key in any of these three keyrings.
>
> Suggested-by: Mimi Zohar <zohar@linux.ibm.com>
> Signed-off-by: Eric Snowberg <eric.snowberg@oracle.com>
> ---
> v3: Initial version
> v4: moved code under CONFIG_INTEGRITY_MOK_KEYRING
> v5: Rename to machine keyring
> v6: Change subject name (suggested by Mimi)
> Rename restrict_link_by_builtin_secondary_and_ca_trusted
> to restrict_link_by_builtin_secondary_and_machine (suggested by
> Mimi)
> v7: Unmodified from v6
> ---
> certs/system_keyring.c | 23 +++++++++++++++++++++++
> include/keys/system_keyring.h | 6 ++++++
> 2 files changed, 29 insertions(+)
>
> diff --git a/certs/system_keyring.c b/certs/system_keyring.c
> index bc7e44fc82c2..71a00add9805 100644
> --- a/certs/system_keyring.c
> +++ b/certs/system_keyring.c
> @@ -99,6 +99,29 @@ void __init set_machine_trusted_keys(struct key *keyring)
> {
> machine_trusted_keys = keyring;
> }
> +
> +/**

This begins the start of kernel doc.

> + * restrict_link_by_builtin_secondary_and_machine

Missing are the parameter defintions. Please refer to
Documentation/doc-guide/kernel-doc.rst for details.

Mimi

> + *
> + * Restrict the addition of keys into a keyring based on the key-to-be-added
> + * being vouched for by a key in either the built-in, the secondary, or
> + * the machine keyrings.
> + */
> +int restrict_link_by_builtin_secondary_and_machine(
> + struct key *dest_keyring,
> + const struct key_type *type,
> + const union key_payload *payload,
> + struct key *restrict_key)
> +{
> + if (machine_trusted_keys && type == &key_type_keyring &&
> + dest_keyring == secondary_trusted_keys &&
> + payload == &machine_trusted_keys->payload)
> + /* Allow the machine keyring to be added to the secondary */
> + return 0;
> +
> + return restrict_link_by_builtin_and_secondary_trusted(dest_keyring, type,
> + payload, restrict_key);
> +}
> #endif
>
> /*
> diff --git a/include/keys/system_keyring.h b/include/keys/system_keyring.h
> index 98c9b10cdc17..2419a735420f 100644
> --- a/include/keys/system_keyring.h
> +++ b/include/keys/system_keyring.h
> @@ -39,8 +39,14 @@ extern int restrict_link_by_builtin_and_secondary_trusted(
> #endif
>
> #ifdef CONFIG_INTEGRITY_MACHINE_KEYRING
> +extern int restrict_link_by_builtin_secondary_and_machine(
> + struct key *dest_keyring,
> + const struct key_type *type,
> + const union key_payload *payload,
> + struct key *restrict_key);
> extern void __init set_machine_trusted_keys(struct key *keyring);
> #else
> +#define restrict_link_by_builtin_secondary_and_machine restrict_link_by_builtin_trusted
> static inline void __init set_machine_trusted_keys(struct key *keyring)
> {
> }