Re: [PATCH v3 05/10] KEYS: Introduce a CA endorsed flag

Jarkko Sakkinen
2023-01-04T11:45:33Z

On Tue, Dec 13, 2022 at 07:33:56PM -0500, Eric Snowberg wrote:
> Some subsystems are interested in knowing if a key has been endorsed
> as or by a Certificate Authority (CA). From the data contained in struct
> key, it is not possible to make this determination after the key
> parsing is complete. Introduce a new Endorsed Certificate Authority
> flag called KEY_FLAG_ECA.
>
> The first type of key to use this is X.509. When a X.509 certificate
> has the keyCertSign Key Usage set and contains the CA bit set, this new
> flag is set. In the future, other usage fields could be added as flags,
> i.e. digitialSignature.
>
> Signed-off-by: Eric Snowberg <eric.snowberg@oracle.com>
> ---
> crypto/asymmetric_keys/x509_public_key.c | 3 +++
> include/linux/key-type.h | 2 ++
> include/linux/key.h | 2 ++
> security/keys/key.c | 8 ++++++++
> 4 files changed, 15 insertions(+)
>
> diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c
> index 0b4943a4592b..fd1d7d6e68e7 100644
> --- a/crypto/asymmetric_keys/x509_public_key.c
> +++ b/crypto/asymmetric_keys/x509_public_key.c
> @@ -208,6 +208,9 @@ static int x509_key_preparse(struct key_preparsed_payload *prep)
> goto error_free_kids;
> }
>

A comment here?

> + if (cert->kcs_set && cert->root_ca)
> + prep->payload_flags |= KEY_ALLOC_PECA;
> +
> /* We're pinning the module by being linked against it */
> __module_get(public_key_subtype.owner);
> prep->payload.data[asym_subtype] = &public_key_subtype;
> diff --git a/include/linux/key-type.h b/include/linux/key-type.h
> index 7d985a1dfe4a..0b500578441c 100644
> --- a/include/linux/key-type.h
> +++ b/include/linux/key-type.h
> @@ -36,6 +36,8 @@ struct key_preparsed_payload {
> size_t datalen; /* Raw datalen */
> size_t quotalen; /* Quota length for proposed payload */
> time64_t expiry; /* Expiry time of key */
> + unsigned int payload_flags; /* Proposed payload flags */
> +#define KEY_ALLOC_PECA 0x0001 /* Proposed Endorsed CA (ECA) key */
> } __randomize_layout;
>
> typedef int (*request_key_actor_t)(struct key *auth_key, void *aux);
> diff --git a/include/linux/key.h b/include/linux/key.h
> index d27477faf00d..21d5a13ee4a9 100644
> --- a/include/linux/key.h
> +++ b/include/linux/key.h
> @@ -236,6 +236,7 @@ struct key {
> #define KEY_FLAG_ROOT_CAN_INVAL 7 /* set if key can be invalidated by root without permission */
> #define KEY_FLAG_KEEP 8 /* set if key should not be removed */
> #define KEY_FLAG_UID_KEYRING 9 /* set if key is a user or user session keyring */
> +#define KEY_FLAG_ECA 10 /* set if key is an Endorsed CA key */
>
> /* the key type and key description string
> * - the desc is used to match a key against search criteria
> @@ -296,6 +297,7 @@ extern struct key *key_alloc(struct key_type *type,
> #define KEY_ALLOC_BYPASS_RESTRICTION 0x0008 /* Override the check on restricted keyrings */
> #define KEY_ALLOC_UID_KEYRING 0x0010 /* allocating a user or user session keyring */
> #define KEY_ALLOC_SET_KEEP 0x0020 /* Set the KEEP flag on the key/keyring */
> +#define KEY_ALLOC_ECA 0x0040 /* Add Endorsed CA key */
>
> extern void key_revoke(struct key *key);
> extern void key_invalidate(struct key *key);
> diff --git a/security/keys/key.c b/security/keys/key.c
> index c45afdd1dfbb..e6b4946aca70 100644
> --- a/security/keys/key.c
> +++ b/security/keys/key.c
> @@ -305,6 +305,8 @@ struct key *key_alloc(struct key_type *type, const char *desc,
> key->flags |= 1 << KEY_FLAG_UID_KEYRING;
> if (flags & KEY_ALLOC_SET_KEEP)
> key->flags |= 1 << KEY_FLAG_KEEP;
> + if (flags & KEY_ALLOC_ECA)
> + key->flags |= 1 << KEY_FLAG_ECA;
>
> #ifdef KEY_DEBUGGING
> key->magic = KEY_DEBUG_MAGIC;
> @@ -929,6 +931,12 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref,
> perm |= KEY_POS_WRITE;
> }
>
> + /* Only allow KEY_ALLOC_ECA flag to be set by preparser contents */
> + if (prep.payload_flags & KEY_ALLOC_PECA)
> + flags |= KEY_ALLOC_ECA;
> + else
> + flags &= ~KEY_ALLOC_ECA;
> +
> /* allocate a new key */
> key = key_alloc(index_key.type, index_key.description,
> cred->fsuid, cred->fsgid, cred, perm, flags, NULL);
> --
> 2.27.0
>

BR, Jarkko