crypto/asymmetric_keys/restrict.c

Source file repositories/reference/linux-study-clean/crypto/asymmetric_keys/restrict.c

File Facts

System
Linux kernel
Corpus path
crypto/asymmetric_keys/restrict.c
Extension
.c
Size
11458 bytes
Lines
367
Domain
Kernel Services
Bucket
crypto
Inferred role
Kernel Services: implementation source
Status
source implementation candidate

Why This File Exists

Shared kernel service surface used by multiple subsystems, including helpers, cryptography, virtualization support, and async I/O infrastructure.

Dependency Surface

Detected Declarations

Annotated Snippet

if (hexlen == 0 || hexlen > sizeof(cakey.data)) {
			pr_err("Missing or invalid ca_keys id\n");
			return 1;
		}

		ret = __asymmetric_key_hex_to_key_id(str + 3, p, hexlen);
		if (ret < 0)
			pr_err("Unparsable ca_keys id hex string\n");
		else
			ca_keyid = p;	/* owner key 'id:xxxxxx' */
	} else if (strcmp(str, "builtin") == 0) {
		use_builtin_keys = true;
	}

	return 1;
}
__setup("ca_keys=", ca_keys_setup);
#endif

/**
 * restrict_link_by_signature - Restrict additions to a ring of public 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 the new certificate against the ones in the trust keyring.  If one of
 * those is the signing key and validates the new certificate, then mark the
 * new certificate as being trusted.
 *
 * Returns 0 if the new certificate was accepted, -ENOKEY if we couldn't find a
 * matching parent certificate in the trusted list, -EKEYREJECTED if the
 * signature check fails or the key is blacklisted, -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_signature(struct key *dest_keyring,
			       const struct key_type *type,
			       const union key_payload *payload,
			       struct key *trust_keyring)
{
	const struct public_key_signature *sig;
	struct key *key;
	int ret;

	pr_devel("==>%s()\n", __func__);

	if (!trust_keyring)
		return -ENOKEY;

	if (type != &key_type_asymmetric)
		return -EOPNOTSUPP;

	sig = payload->data[asym_auth];
	if (!sig)
		return -ENOPKG;
	if (!sig->auth_ids[0] && !sig->auth_ids[1] && !sig->auth_ids[2])
		return -ENOKEY;

	if (ca_keyid && !asymmetric_key_id_partial(sig->auth_ids[1], ca_keyid))
		return -EPERM;

	/* See if we have a key that signed this one. */
	key = find_asymmetric_key(trust_keyring,
				  sig->auth_ids[0], sig->auth_ids[1],
				  sig->auth_ids[2], false);
	if (IS_ERR(key))
		return -ENOKEY;

	if (use_builtin_keys && !test_bit(KEY_FLAG_BUILTIN, &key->flags))
		ret = -ENOKEY;
	else if (IS_BUILTIN(CONFIG_SECONDARY_TRUSTED_KEYRING_SIGNED_BY_BUILTIN) &&
		 !strcmp(dest_keyring->description, ".secondary_trusted_keys") &&
		 !test_bit(KEY_FLAG_BUILTIN, &key->flags))
		ret = -ENOKEY;
	else
		ret = verify_signature(key, sig);
	key_put(key);
	return ret;
}

/**
 * restrict_link_by_ca - Restrict additions to a ring of CA keys
 * @dest_keyring: Keyring being linked to.
 * @type: The type of key being added.
 * @payload: The payload of the new key.
 * @trust_keyring: Unused.
 *
 * Check if the new certificate is a CA. If it is a CA, then mark the new
 * certificate as being ok to link.

Annotation

Implementation Notes