diff --git a/certs/system_keyring.c b/certs/system_keyring.c
index a7a49b17ceb1fe837b786597170826e87dac33e4..b348e0898d34a251ddff092b07b15a5b8f0e0795 100644
--- a/certs/system_keyring.c
+++ b/certs/system_keyring.c
@@ -51,6 +51,26 @@ int restrict_link_by_builtin_trusted(struct key *dest_keyring,
builtin_trusted_keys);
}
+/**
+ * restrict_link_by_digsig_builtin - Restrict digitalSignature key additions by the built-in keyring
+ * @dest_keyring: Keyring being linked to.
+ * @type: The type of key being added.
+ * @payload: The payload of the new key.
+ * @restriction_key: A ring of keys that can be used to vouch for the new cert.
+ *
+ * Restrict the addition of keys into a keyring based on the key-to-be-added
+ * being vouched for by a key in the built in system keyring. The new key
+ * must have the digitalSignature usage field set.
+ */
+int restrict_link_by_digsig_builtin(struct key *dest_keyring,
+ const struct key_type *type,
+ const union key_payload *payload,
+ struct key *restriction_key)
+{
+ return restrict_link_by_digsig(dest_keyring, type, payload,
+ builtin_trusted_keys);
+}
+
#ifdef CONFIG_SECONDARY_TRUSTED_KEYRING
/**
* restrict_link_by_builtin_and_secondary_trusted - Restrict keyring
@@ -83,6 +103,35 @@ int restrict_link_by_builtin_and_secondary_trusted(
secondary_trusted_keys);
}
+/**
+ * restrict_link_by_digsig_builtin_and_secondary - Restrict by digitalSignature.
+ * @dest_keyring: Keyring being linked to.
+ * @type: The type of key being added.
+ * @payload: The payload of the new key.
+ * @restrict_key: A ring of keys that can be used to vouch for the new cert.
+ *
+ * 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 or the secondary system
+ * keyrings. The new key must have the digitalSignature usage field set.
+ */
+int restrict_link_by_digsig_builtin_and_secondary(struct key *dest_keyring,
+ const struct key_type *type,
+ const union key_payload *payload,
+ struct key *restrict_key)
+{
+ /* If we have a secondary trusted keyring, then that contains a link
+ * through to the builtin keyring and the search will follow that link.
+ */
+ if (type == &key_type_keyring &&
+ dest_keyring == secondary_trusted_keys &&
+ payload == &builtin_trusted_keys->payload)
+ /* Allow the builtin keyring to be added to the secondary */
+ return 0;
+
+ return restrict_link_by_digsig(dest_keyring, type, payload,
+ secondary_trusted_keys);
+}
+
/*
* Allocate a struct key_restriction for the "builtin and secondary trust"
* keyring. Only for use in system_trusted_keyring_init().
diff --git a/crypto/asymmetric_keys/restrict.c b/crypto/asymmetric_keys/restrict.c
index 276bdb62749882a838d3305461e3eb3a58e8ab89..6b69ea40da237334196eca452416272d8403cfe2 100644
--- a/crypto/asymmetric_keys/restrict.c
+++ b/crypto/asymmetric_keys/restrict.c
@@ -148,6 +148,50 @@ int restrict_link_by_ca(struct key *dest_keyring,
return 0;
}
+/**
+ * restrict_link_by_digsig - Restrict additions to a ring of digsig keys
+ * @dest_keyring: Keyring being linked to.
+ * @type: The type of key being added.
+ * @payload: The payload of the new key.
+ * @trust_keyring: A ring of keys that can be used to vouch for the new cert.
+ *
+ * Check if the new certificate has digitalSignature usage set. If it is,
+ * then mark the new certificate as being ok to link. Afterwards verify
+ * the new certificate against the ones in the trust_keyring.
+ *
+ * Returns 0 if the new certificate was accepted, -ENOKEY if the
+ * certificate is not a digsig. -ENOPKG if the signature uses unsupported
+ * crypto, or some other error if there is a matching certificate but
+ * the signature check cannot be performed.
+ */
+int restrict_link_by_digsig(struct key *dest_keyring,
+ const struct key_type *type,
+ const union key_payload *payload,
+ struct key *trust_keyring)
+{
+ const struct public_key *pkey;
+
+ if (type != &key_type_asymmetric)
+ return -EOPNOTSUPP;
+
+ pkey = payload->data[asym_crypto];
+
+ if (!pkey)
+ return -ENOPKG;
+
+ if (!test_bit(KEY_EFLAG_DIGITALSIG, &pkey->key_eflags))
+ return -ENOKEY;
+
+ if (test_bit(KEY_EFLAG_CA, &pkey->key_eflags))
+ return -ENOKEY;
+
+ if (test_bit(KEY_EFLAG_KEYCERTSIGN, &pkey->key_eflags))
+ return -ENOKEY;
+
+ return restrict_link_by_signature(dest_keyring, type, payload,
+ trust_keyring);
+}
+
static bool match_either_id(const struct asymmetric_key_id **pair,
const struct asymmetric_key_id *single)
{
diff --git a/include/crypto/public_key.h b/include/crypto/public_key.h
index 8fadd561c50eeefa02ae738c4e65ca969937c40f..462f8a34cdf872b17111abf68b4eeb9a8577b6b2 100644
--- a/include/crypto/public_key.h
+++ b/include/crypto/public_key.h
@@ -78,6 +78,10 @@ extern int restrict_link_by_ca(struct key *dest_keyring,
const struct key_type *type,
const union key_payload *payload,
struct key *trust_keyring);
+int restrict_link_by_digsig(struct key *dest_keyring,
+ const struct key_type *type,
+ const union key_payload *payload,
+ struct key *trust_keyring);
#else
static inline int restrict_link_by_ca(struct key *dest_keyring,
const struct key_type *type,
@@ -86,6 +90,14 @@ static inline int restrict_link_by_ca(struct key *dest_keyring,
{
return 0;
}
+
+static inline int restrict_link_by_digsig(struct key *dest_keyring,
+ const struct key_type *type,
+ const union key_payload *payload,
+ struct key *trust_keyring)
+{
+ return 0;
+}
#endif
extern int query_asymmetric_key(const struct kernel_pkey_params *,
diff --git a/include/keys/system_keyring.h b/include/keys/system_keyring.h
index 91e080efb918905d71132d2c986ef2b700639466..7e2583208820118aba2bf4f08a749bde98b5ccd6 100644
--- a/include/keys/system_keyring.h
+++ b/include/keys/system_keyring.h
@@ -23,10 +23,15 @@ extern int restrict_link_by_builtin_trusted(struct key *keyring,
const struct key_type *type,
const union key_payload *payload,
struct key *restriction_key);
+int restrict_link_by_digsig_builtin(struct key *dest_keyring,
+ const struct key_type *type,
+ const union key_payload *payload,
+ struct key *restriction_key);
extern __init int load_module_cert(struct key *keyring);
#else
#define restrict_link_by_builtin_trusted restrict_link_reject
+#define restrict_link_by_digsig_builtin restrict_link_reject
static inline __init int load_module_cert(struct key *keyring)
{
@@ -41,8 +46,13 @@ extern int restrict_link_by_builtin_and_secondary_trusted(
const struct key_type *type,
const union key_payload *payload,
struct key *restriction_key);
+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);
#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
#endif
#ifdef CONFIG_INTEGRITY_MACHINE_KEYRING