Thanks Mimi for your comments.
On Wed, 21 Oct 2020 at 08:51, Mimi Zohar zohar@linux.ibm.com wrote:
On Wed, 2020-10-07 at 15:37 +0530, Sumit Garg wrote:
+/*
- trusted_destroy - clear and free the key's payload
- */
+static void trusted_destroy(struct key *key) +{
kfree_sensitive(key->payload.data[0]);+}
+struct key_type key_type_trusted = {
.name = "trusted",.instantiate = trusted_instantiate,.update = trusted_update,.destroy = trusted_destroy,.describe = user_describe,.read = trusted_read,+}; +EXPORT_SYMBOL_GPL(key_type_trusted);
+static int __init init_trusted(void) +{
int i, ret = 0;for (i = 0; i < ARRAY_SIZE(trusted_key_sources); i++) {if (trusted_key_source &&strncmp(trusted_key_source, trusted_key_sources[i].name,strlen(trusted_key_sources[i].name)))continue;trusted_key_ops = trusted_key_sources[i].ops;ret = trusted_key_ops->init();if (!ret)break;}In the case when the module paramater isn't specified and both TPM and TEE are enabled, trusted_key_ops is set to the last source initialized.
I guess there is some misunderstanding. Here it's only a single trust source (TPM *or* TEE) is initialized and only that trust source would be active at runtime. And trusted_key_ops would be initialized to the first trust source whose initialization is successful (see check: "if (!ret)").
After patch 2/4, the last trusted source initialized is TEE. If the intention is to limit it to either TPM or TEE, then trusted_key_ops should have a default value, which could be overwritten at runtime. That would address Luke Hind's concerns of making the decision at compile time.
I think traversing the trust source list with the initial value being TPM would be default value.
trusted_key_ops should be defined as __ro_after_init, like is currently done for other LSM structures.
Sure, will do.
/** encrypted_keys.ko depends on successful load of this module even if* trusted key implementation is not found.*/if (ret == -ENODEV)return 0;return ret;+}
+static void __exit cleanup_trusted(void) +{
trusted_key_ops->exit();If the intention is really to support both TPM and TEE trusted keys at the same time, as James suggested, then the same "for" loop as in init_trusted() is needed here and probably elsewhere.
Current intention is to only support a single trust source (TPM or TEE) at runtime. But in future if there are use-cases then framework can be extended to support multiple trust sources at runtime as well.
-Sumit
thanks,
Mimi