AOSP change: Add fscrypt-provisioning to keyring (93a12be9) · Commits · e / devices / android_kernel_fairphone_FP5

fs/crypto/keyring.c

+132 −13

Original line number	Diff line number	Diff line
		@@ -465,6 +465,111 @@ static int add_master_key(struct super_block *sb,
		return err;
		}

		static int fscrypt_provisioning_key_preparse(struct key_preparsed_payload *prep)
		{
		const struct fscrypt_provisioning_key_payload *payload = prep->data;

		BUILD_BUG_ON(FSCRYPT_MAX_HW_WRAPPED_KEY_SIZE < FSCRYPT_MAX_KEY_SIZE);

		if (prep->datalen < sizeof(*payload) + FSCRYPT_MIN_KEY_SIZE \|\|
		prep->datalen > sizeof(*payload) + FSCRYPT_MAX_HW_WRAPPED_KEY_SIZE)
		return -EINVAL;

		if (payload->type != FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR &&
		payload->type != FSCRYPT_KEY_SPEC_TYPE_IDENTIFIER)
		return -EINVAL;

		if (payload->__reserved)
		return -EINVAL;

		prep->payload.data[0] = kmemdup(payload, prep->datalen, GFP_KERNEL);
		if (!prep->payload.data[0])
		return -ENOMEM;

		prep->quotalen = prep->datalen;
		return 0;
		}

		static void fscrypt_provisioning_key_free_preparse(
		struct key_preparsed_payload *prep)
		{
		kzfree(prep->payload.data[0]);
		}

		static void fscrypt_provisioning_key_describe(const struct key *key,
		struct seq_file *m)
		{
		seq_puts(m, key->description);
		if (key_is_positive(key)) {
		const struct fscrypt_provisioning_key_payload *payload =
		key->payload.data[0];

		seq_printf(m, ": %u [%u]", key->datalen, payload->type);
		}
		}

		static void fscrypt_provisioning_key_destroy(struct key *key)
		{
		kzfree(key->payload.data[0]);
		}

		static struct key_type key_type_fscrypt_provisioning = {
		.name = "fscrypt-provisioning",
		.preparse = fscrypt_provisioning_key_preparse,
		.free_preparse = fscrypt_provisioning_key_free_preparse,
		.instantiate = generic_key_instantiate,
		.describe = fscrypt_provisioning_key_describe,
		.destroy = fscrypt_provisioning_key_destroy,
		};

		/*
		* Retrieve the raw key from the Linux keyring key specified by 'key_id', and
		* store it into 'secret'.
		*
		* The key must be of type "fscrypt-provisioning" and must have the field
		* fscrypt_provisioning_key_payload::type set to 'type', indicating that it's
		* only usable with fscrypt with the particular KDF version identified by
		* 'type'. We don't use the "logon" key type because there's no way to
		* completely restrict the use of such keys; they can be used by any kernel API
		* that accepts "logon" keys and doesn't require a specific service prefix.
		*
		* The ability to specify the key via Linux keyring key is intended for cases
		* where userspace needs to re-add keys after the filesystem is unmounted and
		* re-mounted. Most users should just provide the raw key directly instead.
		*/
		static int get_keyring_key(u32 key_id, u32 type,
		struct fscrypt_master_key_secret *secret)
		{
		key_ref_t ref;
		struct key *key;
		const struct fscrypt_provisioning_key_payload *payload;
		int err;

		ref = lookup_user_key(key_id, 0, KEY_NEED_SEARCH);
		if (IS_ERR(ref))
		return PTR_ERR(ref);
		key = key_ref_to_ptr(ref);

		if (key->type != &key_type_fscrypt_provisioning)
		goto bad_key;
		payload = key->payload.data[0];

		/* Don't allow fscrypt v1 keys to be used as v2 keys and vice versa. */
		if (payload->type != type)
		goto bad_key;

		secret->size = key->datalen - sizeof(*payload);
		memcpy(secret->raw, payload->raw, secret->size);
		err = 0;
		goto out_put;

		bad_key:
		err = -EKEYREJECTED;
		out_put:
		key_ref_put(ref);
		return err;
		}

		/* Size of software "secret" derived from hardware-wrapped key */
		#define RAW_SECRET_SIZE 32

		@@ -512,20 +617,28 @@ int fscrypt_ioctl_add_key(struct file filp, void __user _uarg)
		if (memchr_inv(arg.__reserved, 0, sizeof(arg.__reserved)))
		return -EINVAL;

		BUILD_BUG_ON(FSCRYPT_MAX_HW_WRAPPED_KEY_SIZE <
		FSCRYPT_MAX_KEY_SIZE);

		memset(&secret, 0, sizeof(secret));
		if (arg.key_id) {
		if (arg.raw_size != 0)
		return -EINVAL;
		err = get_keyring_key(arg.key_id, arg.key_spec.type, &secret);
		if (err)
		goto out_wipe_secret;
		err = -EINVAL;
		if (!(arg.__flags & __FSCRYPT_ADD_KEY_FLAG_HW_WRAPPED) &&
		secret.size > FSCRYPT_MAX_KEY_SIZE)
		goto out_wipe_secret;
		} else {
		if (arg.raw_size < FSCRYPT_MIN_KEY_SIZE \|\|
		arg.raw_size >
		((arg.__flags & __FSCRYPT_ADD_KEY_FLAG_HW_WRAPPED) ?
		FSCRYPT_MAX_HW_WRAPPED_KEY_SIZE : FSCRYPT_MAX_KEY_SIZE))
		return -EINVAL;

		memset(&secret, 0, sizeof(secret));
		secret.size = arg.raw_size;
		err = -EFAULT;
		if (copy_from_user(secret.raw, uarg->raw, secret.size))
		goto out_wipe_secret;
		}

		switch (arg.key_spec.type) {
		case FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR:
		@@ -1030,8 +1143,14 @@ int __init fscrypt_init_keyring(void)
		if (err)
		goto err_unregister_fscrypt;

		err = register_key_type(&key_type_fscrypt_provisioning);
		if (err)
		goto err_unregister_fscrypt_user;

		return 0;

		err_unregister_fscrypt_user:
		unregister_key_type(&key_type_fscrypt_user);
		err_unregister_fscrypt:
		unregister_key_type(&key_type_fscrypt);
		return err;

include/uapi/linux/fscrypt.h

+12 −1

Original line number	Diff line number	Diff line
		@@ -109,11 +109,22 @@ struct fscrypt_key_specifier {
		} u;
		};

		/*
		* Payload of Linux keyring key of type "fscrypt-provisioning", referenced by
		* fscrypt_add_key_arg::key_id as an alternative to fscrypt_add_key_arg::raw.
		*/
		struct fscrypt_provisioning_key_payload {
		__u32 type;
		__u32 __reserved;
		__u8 raw[];
		};

		/* Struct passed to FS_IOC_ADD_ENCRYPTION_KEY */
		struct fscrypt_add_key_arg {
		struct fscrypt_key_specifier key_spec;
		__u32 raw_size;
		__u32 __reserved[8];
		__u32 key_id;
		__u32 __reserved[7];
		/* N.B.: "temporary" flag, not reserved upstream */
		#define __FSCRYPT_ADD_KEY_FLAG_HW_WRAPPED 0x00000001
		__u32 __flags;