Merge 99ac2551fe64a550e33eea7cb12a01971fefb521 into 4fdb917aae2fb5876e04f88621630712a906a067

Backport 3.6: Fix resource leak in populate transform

CONTRIBUTING.md

@@ -10,6 +10,7 @@ More details on all of these points may be found in the sections below.
 - [Sign-off](#license-and-copyright): all commits must be signed off.
 - [Tests](#tests): please ensure the PR includes adequate tests.
 - [Changelog](#documentation): if needed, please provide a changelog entry.
+- [development](#development-branch): please ensure the PR is against the development branch.
 - [Backports](#long-term-support-branches): provide a backport if needed (it's fine to wait until the main PR is accepted).
 
 Coding Standards
@@ -53,6 +54,15 @@ It would be highly appreciated if contributions are backported to LTS branches i
 The list of maintained branches can be found in the [Current Branches section
 of BRANCHES.md](BRANCHES.md#current-branches).
 
+development branch
+------------------
+
+development branch is where all development happens. Some PRs will be backported into the LTS branches, but not all. So all PRs must first start with development. We won't merge a PR into development if we want backport PRs and they are not present. Very specifically, gatekeepers should merge all PRs at the same time. 
+
+Now, some people will create the backports at the same time as the main PR. If changes are required, this means extra work.
+
+It is fine to wait until we are happy with a PR before creating backports. But it's usually best to start with a PR against development (obviously there are special cases of issues that are only in an LTS branch, but ignoring that for the sake of a generally applicable rule) and then create backport PRs if required or requested. 
+
 Tests
 -----
 As mentioned, tests that show the correctness of the feature or bug fix should be added to the pull request, if no such tests exist.

ChangeLog.d/tls13-transform-resource-leak.txt

@@ -0,0 +1,4 @@
+Bugfix
+   * Fix resource leaks in TLS 1.3 transform setup when a setup step fails
+     after allocating cipher contexts or importing the encryption traffic key.
+     Fixes #10917.

library/ssl_tls13_keys.c

@@ -977,6 +977,7 @@ int mbedtls_ssl_tls13_populate_transform(
     if ((ret = mbedtls_cipher_setup(&transform->cipher_ctx_dec,
                                     cipher_info)) != 0) {
         MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_cipher_setup", ret);
+        mbedtls_ssl_transform_free(transform);
         return ret;
     }
 #endif /* MBEDTLS_USE_PSA_CRYPTO */
@@ -999,6 +1000,9 @@ int mbedtls_ssl_tls13_populate_transform(
 #endif /* MBEDTLS_SSL_CLI_C */
     {
         /* should not happen */
+#if !defined(MBEDTLS_USE_PSA_CRYPTO)
+        mbedtls_ssl_transform_free(transform);
+#endif
         return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
     }
 
@@ -1010,6 +1014,7 @@ int mbedtls_ssl_tls13_populate_transform(
                                      key_enc, (int) mbedtls_cipher_info_get_key_bitlen(cipher_info),
                                      MBEDTLS_ENCRYPT)) != 0) {
         MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_cipher_setkey", ret);
+        mbedtls_ssl_transform_free(transform);
         return ret;
     }
 
@@ -1017,6 +1022,7 @@ int mbedtls_ssl_tls13_populate_transform(
                                      key_dec, (int) mbedtls_cipher_info_get_key_bitlen(cipher_info),
                                      MBEDTLS_DECRYPT)) != 0) {
         MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_cipher_setkey", ret);
+        mbedtls_ssl_transform_free(transform);
         return ret;
     }
 #endif /* MBEDTLS_USE_PSA_CRYPTO */
@@ -1081,6 +1087,8 @@ int mbedtls_ssl_tls13_populate_transform(
                                      &transform->psa_key_dec)) != PSA_SUCCESS) {
             MBEDTLS_SSL_DEBUG_RET(
                 1, "psa_import_key", PSA_TO_MBEDTLS_ERR(status));
+            psa_destroy_key(transform->psa_key_enc);
+            transform->psa_key_enc = MBEDTLS_SVC_KEY_ID_INIT;
             return PSA_TO_MBEDTLS_ERR(status);
         }
     }

tests/suites/test_suite_ssl.data

@@ -3003,6 +3003,9 @@ SSL TLS 1.3 Record Encryption RFC 8448 Example #2
 depends_on:PSA_WANT_KEY_TYPE_AES:PSA_WANT_ALG_GCM:PSA_WANT_ALG_SHA_256
 ssl_tls13_record_protection:MBEDTLS_TLS1_3_AES_128_GCM_SHA256:MBEDTLS_SSL_IS_SERVER:1:1:"9f02283b6c9c07efc26bb9f2ac92e356":"cf782b88dd83549aadf1e984":"17422dda596ed5d9acd890e3c63f5051":"5b78923dee08579033e523d9":"000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f3031":"2e937e11ef4ac740e538ad36005fc4a46932fc3225d05f82aa1b36e30efaf97d90e6dffc602dcb501a59a8fcc49c4bf2e5f0a21c0047c2abf332540dd032e167c2955d"
 
+TLS 1.3 transform frees encryption key if decryption key import fails
+ssl_tls13_populate_transform_second_key_import_failure
+
 SSL TLS 1.3 Key schedule: Application secrets derivation helper
 # Vector from RFC 8448
 depends_on:PSA_WANT_ALG_SHA_256

tests/suites/test_suite_ssl.function

@@ -5,6 +5,7 @@
 #include <mbedtls/pk.h>
 #include <ssl_tls13_keys.h>
 #include <ssl_tls13_invasive.h>
+#include <psa_crypto_slot_management.h>
 #include <test/ssl_helpers.h>
 #include <test/ssl_helpers_internal.h>
 
@@ -34,6 +35,39 @@
 #define TEST_SSL_CONTEXT_LOAD_OOB_OUT_CID  1
 #define TEST_SSL_CONTEXT_LOAD_OOB_ALPN     2
 
+#if defined(MBEDTLS_PSA_KEY_STORE_DYNAMIC)
+#if defined(MBEDTLS_TEST_HOOKS) && defined(MBEDTLS_SSL_CLI_C) && \
+    defined(MBEDTLS_PSA_CRYPTO_C) && defined(MBEDTLS_SSL_PROTO_TLS1_3) && \
+    defined(MBEDTLS_USE_PSA_CRYPTO)
+#define SSL_TEST_KEY_SLICE_1_LENGTH 4
+#define SSL_TEST_KEY_SLICE_2_LENGTH 10
+static size_t ssl_test_tiny_key_slice_length(size_t slice_idx)
+{
+    switch (slice_idx) {
+        case 1: return SSL_TEST_KEY_SLICE_1_LENGTH;
+        case 2: return SSL_TEST_KEY_SLICE_2_LENGTH;
+        default: return 1;
+    }
+}
+
+/* In the below definition SSL_TEST_KEY_SLICE_1_LENGTH has 4 slots and
+ * SSL_TEST_KEY_SLICE_2_LENGTH has 10 all other slices have 1.
+ * psa_key_slot_volatile_slice_count() returns the total number of slices.
+ * However we have already countes slices 1 and 2, so we mustr subtract 2 from
+ * this number to avoid double counting.
+ */
+
+#define SSL_TEST_MAX_VOLATILE_KEYS                         \
+    (SSL_TEST_KEY_SLICE_1_LENGTH +                         \
+     SSL_TEST_KEY_SLICE_2_LENGTH +                         \
+     psa_key_slot_volatile_slice_count() - 2)
+#endif /* MBEDTLS_TEST_HOOKS && MBEDTLS_SSL_CLI_C &&
+          MBEDTLS_PSA_CRYPTO_C && MBEDTLS_SSL_PROTO_TLS1_3 &&
+          MBEDTLS_USE_PSA_CRYPTO */
+#else /* MBEDTLS_PSA_KEY_STORE_DYNAMIC */
+#define SSL_TEST_MAX_VOLATILE_KEYS MBEDTLS_PSA_KEY_SLOT_COUNT
+#endif /* MBEDTLS_PSA_KEY_STORE_DYNAMIC */
+
 #if defined(MBEDTLS_SSL_PROTO_TLS1_2) && \
     defined(MBEDTLS_SSL_SESSION_TICKETS) && \
     defined(MBEDTLS_SSL_CLI_C) && defined(MBEDTLS_SSL_SRV_C) && \
@@ -2461,6 +2495,85 @@ exit:
 }
 /* END_CASE */
 
+/* BEGIN_CASE depends_on:MBEDTLS_SSL_PROTO_TLS1_3:MBEDTLS_SSL_CLI_C:SSL_TEST_MAX_VOLATILE_KEYS:MBEDTLS_PSA_CRYPTO_C:MBEDTLS_USE_PSA_CRYPTO */
+void ssl_tls13_populate_transform_second_key_import_failure(void)
+{
+    mbedtls_ssl_key_set traffic_keys;
+    mbedtls_ssl_transform transform;
+    mbedtls_svc_key_id_t *keys = NULL;
+    psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
+    mbedtls_psa_stats_t stats_before, stats_after;
+    psa_status_t status = PSA_SUCCESS;
+    size_t i = 0;
+
+    memset(&traffic_keys, 0, sizeof(traffic_keys));
+    mbedtls_ssl_transform_init(&transform);
+
+#if defined(MBEDTLS_PSA_KEY_STORE_DYNAMIC) && defined(MBEDTLS_TEST_HOOKS)
+    mbedtls_test_hook_psa_volatile_key_slice_length =
+        ssl_test_tiny_key_slice_length;
+#endif
+
+    PSA_INIT();
+    TEST_CALLOC(keys, SSL_TEST_MAX_VOLATILE_KEYS + 1);
+
+    psa_set_key_usage_flags(&attributes, PSA_KEY_USAGE_EXPORT);
+    psa_set_key_type(&attributes, PSA_KEY_TYPE_RAW_DATA);
+
+    /* Allow one more attempt than the maximum number of volatile keys so
+     * that the loop ends because the key store is full. */
+    while (i <= SSL_TEST_MAX_VOLATILE_KEYS) {
+        status = psa_import_key(&attributes,
+                                (const uint8_t *) &i, sizeof(i),
+                                &keys[i]);
+        if (status == PSA_ERROR_INSUFFICIENT_MEMORY) {
+            break;
+        }
+        PSA_ASSERT(status);
+        i++;
+    }
+    TEST_EQUAL(status, PSA_ERROR_INSUFFICIENT_MEMORY);
+    TEST_ASSERT(i > 0);
+
+    /* Leave exactly one slot free: the encryption key import consumes it,
+     * then the decryption key import fails. */
+    PSA_ASSERT(psa_destroy_key(keys[--i]));
+    keys[i] = MBEDTLS_SVC_KEY_ID_INIT;
+    mbedtls_psa_get_stats(&stats_before);
+
+    traffic_keys.key_len = 16;
+    traffic_keys.iv_len = 12;
+    TEST_ASSERT(mbedtls_ssl_tls13_populate_transform(
+                    &transform, MBEDTLS_SSL_IS_CLIENT,
+                    MBEDTLS_TLS1_3_AES_128_GCM_SHA256,
+                    &traffic_keys, NULL) != 0);
+
+    /* The first import must be rolled back when the second one fails. */
+    TEST_ASSERT(mbedtls_svc_key_id_is_null(transform.psa_key_enc));
+
+    /* Also check the key store itself: the failed operation must neither
+     * consume a slot nor leave the only free slot unusable. */
+    mbedtls_psa_get_stats(&stats_after);
+    TEST_EQUAL(stats_after.volatile_slots, stats_before.volatile_slots);
+    TEST_EQUAL(stats_after.empty_slots, stats_before.empty_slots);
+    PSA_ASSERT(psa_import_key(&attributes,
+                              (const uint8_t *) &i, sizeof(i),
+                              &keys[i]));
+    i++;
+
+exit:
+    mbedtls_ssl_transform_free(&transform);
+    while (i > 0) {
+        psa_destroy_key(keys[--i]);
+    }
+    mbedtls_free(keys);
+    PSA_DONE();
+#if defined(MBEDTLS_PSA_KEY_STORE_DYNAMIC) && defined(MBEDTLS_TEST_HOOKS)
+    mbedtls_test_hook_psa_volatile_key_slice_length = NULL;
+#endif
+}
+/* END_CASE */
+
 /* BEGIN_CASE depends_on:MBEDTLS_SSL_PROTO_TLS1_3 */
 void ssl_tls13_key_evolution(int hash_alg,
                              data_t *secret,