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fix(esp-tls): track opaque PSA key ownership and cover the secure-element path

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Replace the key-lifetime check with explicit ownership tracking so a
caller-supplied volatile PSA key is also preserved on cleanup, and drop the
DS/HARDWARE_ECDSA compile guard so the ESP_KEY_SOURCE_PSA path is released on
pure secure-element builds.

(cherry picked from commit 7cdd0b5960)
This commit is contained in:
Aditya Patwardhan
2026-07-09 11:17:03 +05:30
parent 2627f6e941
commit 5285c70499
2 changed files with 23 additions and 20 deletions
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components/esp-tls/esp_tls_mbedtls.c
+19 -20
View File
@@ -484,31 +484,28 @@ void esp_mbedtls_cleanup(esp_tls_t *tls)
mbedtls_x509_crt_free(&tls->cacert);
mbedtls_x509_crt_free(&tls->clientcert);
/* For opaque keys (DS peripheral, hardware ECDSA), mbedtls_pk_free() does
* not destroy the PSA key — ownership is external. Destroy it manually
* before calling mbedtls_pk_free(). mbedtls_pk_wrap_psa() sets the pk_info
* to mbedtls_{rsa,ecdsa}_opaque_info, both of which have type
* MBEDTLS_PK_OPAQUE — so a single check covers both DS and ECDSA paths.
* clientkey and serverkey share storage via union, so one branch suffices.
*
* Only destroy volatile keys created internally by the DS/ECDSA peripheral
* paths. Keys wrapped from an external clientkey_psa_id are caller-owned
* (typically persistent) and must not be destroyed here. */
#if defined(CONFIG_ESP_TLS_USE_DS_PERIPHERAL) || defined(CONFIG_MBEDTLS_HARDWARE_ECDSA_SIGN)
/* For opaque keys, mbedtls_pk_free() does not release the underlying PSA
* key — ownership is tracked separately. Dispatch on ownership, not on the
* key lifetime: a caller-supplied key (ESP_KEY_SOURCE_PSA, e.g. a
* pre-provisioned secure element) is owned externally and must never be
* destroyed on connection close — at most purge it to drop the cached slot
* (a no-op for a volatile key). A key esp-tls created itself is always
* volatile and is destroyed to release its slot. mbedtls_pk_wrap_psa() sets
* the pk_info to mbedtls_{rsa,ecdsa}_opaque_info, both of type
* MBEDTLS_PK_OPAQUE, so one runtime check covers every opaque path (DS
* peripheral, hardware ECDSA, and caller-supplied PSA keys). clientkey and
* serverkey share storage via union, so one branch suffices. */
if (mbedtls_pk_get_type(&tls->clientkey) == MBEDTLS_PK_OPAQUE) {
if (tls->clientkey.MBEDTLS_PRIVATE(priv_id) != PSA_KEY_ID_NULL) {
psa_key_attributes_t attrs = PSA_KEY_ATTRIBUTES_INIT;
if (psa_get_key_attributes(tls->clientkey.MBEDTLS_PRIVATE(priv_id),
&attrs) == PSA_SUCCESS) {
if (PSA_KEY_LIFETIME_IS_VOLATILE(psa_get_key_lifetime(&attrs))) {
psa_destroy_key(tls->clientkey.MBEDTLS_PRIVATE(priv_id));
}
psa_reset_key_attributes(&attrs);
psa_key_id_t kid = tls->clientkey.MBEDTLS_PRIVATE(priv_id);
if (kid != PSA_KEY_ID_NULL) {
if (tls->opaque_key_is_external) {
psa_purge_key(kid);
} else {
psa_destroy_key(kid);
}
tls->clientkey.MBEDTLS_PRIVATE(priv_id) = PSA_KEY_ID_NULL;
}
}
#endif
mbedtls_pk_free(&tls->clientkey);
mbedtls_ssl_config_free(&tls->conf);
@@ -780,6 +777,7 @@ static esp_err_t set_server_config(esp_tls_cfg_server_t *cfg, esp_tls_t *tls)
}
mbedtls_svc_key_id_t key_id = cfg->server_key->psa.key_id;
mbedtls_pk_init(&tls->serverkey);
tls->opaque_key_is_external = true;
ret = mbedtls_pk_wrap_psa(&tls->serverkey, key_id);
if (ret != 0) {
ESP_LOGE(TAG, "mbedtls_pk_wrap_psa returned -0x%04X", -ret);
@@ -1052,6 +1050,7 @@ esp_err_t set_client_config(const char *hostname, size_t hostlen, esp_tls_cfg_t
}
mbedtls_svc_key_id_t key_id = cfg->client_key->psa.key_id;
mbedtls_pk_init(&tls->clientkey);
tls->opaque_key_is_external = true;
ret = mbedtls_pk_wrap_psa(&tls->clientkey, key_id);
if (ret != 0) {
ESP_LOGE(TAG, "mbedtls_pk_wrap_psa returned -0x%04X", -ret);
components/esp-tls/private_include/esp_tls_private.h
+4
View File
@@ -52,6 +52,10 @@ struct esp_tls {
mbedtls_pk_context serverkey; /*!< Container for the private key of the server
certificate */
};
bool opaque_key_is_external; /*!< True when the opaque PSA client/server key was supplied
by the caller (ESP_KEY_SOURCE_PSA). Such keys are owned
externally and must never be destroyed on cleanup. */
#ifdef CONFIG_MBEDTLS_HARDWARE_ECDSA_SIGN
bool use_ecdsa_peripheral; /*!< Use the ECDSA peripheral for the private key operations. */
uint8_t ecdsa_efuse_blk; /*!< The efuse block number where the ECDSA key is stored. */