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Harden serialized data deserialization

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Reject malformed TLS 1.3 serialized sessions instead of accepting
unterminated strings or extra trailing data, and reject serialized SSL
contexts whose DTLS Connection ID length exceeds the maximum supported
size instead of overflowing the internal buffer.

Backport of #10715 (development). The dedicated CID-length test from
#10715 relies on test helpers that do not exist on 3.6 (notably
mbedtls_test_ssl_dtls_join_endpoints and mbedtls_test_ssl_perform_connection)
and is therefore omitted from this backport; the production fix and the
TLS 1.3 session-load tests are backported unchanged.

Signed-off-by: Nadav0077 <[email protected]>
This commit is contained in:
Nadav0077
2026-05-22 13:16:58 +03:00
parent 2f2b202f8e
commit b0d5c0c80a
4 changed files with 124 additions and 4 deletions
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ChangeLog.d/serialized-data-load-hardening.txt
+5
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@@ -0,0 +1,5 @@
Bugfix
* Reject malformed TLS 1.3 serialized sessions instead of accepting
unterminated strings or extra trailing data.
* Reject serialized SSL contexts whose DTLS Connection ID length exceeds
the maximum supported size, instead of overflowing the internal buffer.
library/ssl_tls.c
+27 -4
View File
@@ -4035,6 +4035,12 @@ static int ssl_tls13_session_load(mbedtls_ssl_session *session,
}
if (alpn_len > 0) {
/* The data is about to be used as a null-terminated string, so
* check that it actually is one. */
if (p[alpn_len - 1] != '\0') {
return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
}
int ret = mbedtls_ssl_session_set_ticket_alpn(session, (char *) p);
if (ret != 0) {
return ret;
@@ -4060,11 +4066,16 @@ static int ssl_tls13_session_load(mbedtls_ssl_session *session,
return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
}
if (hostname_len > 0) {
session->hostname = mbedtls_calloc(1, hostname_len);
if (session->hostname == NULL) {
return MBEDTLS_ERR_SSL_ALLOC_FAILED;
/* The data is about to be used as a null-terminated string, so
* check that it actually is one. */
if (p[hostname_len - 1] != '\0') {
return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
}
int ret = mbedtls_ssl_session_set_hostname(session, (const char *) p);
if (ret != 0) {
return ret;
}
memcpy(session->hostname, p, hostname_len);
p += hostname_len;
}
#endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */
@@ -4102,6 +4113,10 @@ static int ssl_tls13_session_load(mbedtls_ssl_session *session,
}
#endif /* MBEDTLS_SSL_CLI_C */
if (p != end) {
return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
}
return 0;
}
@@ -5440,6 +5455,10 @@ static int ssl_context_load(mbedtls_ssl_context *ssl,
return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
}
if (ssl->transform->in_cid_len > sizeof(ssl->transform->in_cid)) {
return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
}
memcpy(ssl->transform->in_cid, p, ssl->transform->in_cid_len);
p += ssl->transform->in_cid_len;
@@ -5449,6 +5468,10 @@ static int ssl_context_load(mbedtls_ssl_context *ssl,
return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
}
if (ssl->transform->out_cid_len > sizeof(ssl->transform->out_cid)) {
return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
}
memcpy(ssl->transform->out_cid, p, ssl->transform->out_cid_len);
p += ssl->transform->out_cid_len;
#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
tests/suites/test_suite_ssl.data
+13
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@@ -3185,6 +3185,19 @@ TLS 1.3: SRV: Session serialization, load buffer size
depends_on:MBEDTLS_SSL_PROTO_TLS1_3:MBEDTLS_SSL_SESSION_TICKETS:MBEDTLS_SSL_SRV_C
ssl_serialize_session_load_buf_size:0:"":MBEDTLS_SSL_IS_SERVER:MBEDTLS_SSL_VERSION_TLS1_3
TLS 1.3: Session serialization rejects trailing data
depends_on:MBEDTLS_SSL_CLI_C
ssl_tls13_session_load_rejects_bad_serialized_data:MBEDTLS_SSL_IS_CLIENT:TEST_TLS13_SESSION_LOAD_TRAILING_DATA
TLS 1.3: Session serialization rejects hostname without terminator
depends_on:MBEDTLS_SSL_CLI_C:MBEDTLS_SSL_SERVER_NAME_INDICATION
ssl_tls13_session_load_rejects_bad_serialized_data:MBEDTLS_SSL_IS_CLIENT:TEST_TLS13_SESSION_LOAD_HOSTNAME_NO_NUL
TLS 1.3: Session serialization rejects ALPN without terminator
depends_on:MBEDTLS_SSL_SRV_C:MBEDTLS_SSL_EARLY_DATA:MBEDTLS_SSL_ALPN
ssl_tls13_session_load_rejects_bad_serialized_data:MBEDTLS_SSL_IS_SERVER:TEST_TLS13_SESSION_LOAD_ALPN_NO_NUL
Test configuration of EC groups through mbedtls_ssl_conf_curves()
conf_curve:
tests/suites/test_suite_ssl.function
+79
View File
@@ -22,6 +22,11 @@
#define TEST_EARLY_DATA_NO_INITIAL_ALPN 6
#define TEST_EARLY_DATA_NO_LATER_ALPN 7
/* Mutations for ssl_tls13_session_load_rejects_bad_serialized_data */
#define TEST_TLS13_SESSION_LOAD_TRAILING_DATA 0
#define TEST_TLS13_SESSION_LOAD_HOSTNAME_NO_NUL 1
#define TEST_TLS13_SESSION_LOAD_ALPN_NO_NUL 2
#if (!defined(MBEDTLS_SSL_PROTO_TLS1_2)) && \
defined(MBEDTLS_SSL_EARLY_DATA) && defined(MBEDTLS_SSL_CLI_C) && \
defined(MBEDTLS_SSL_SRV_C) && defined(MBEDTLS_DEBUG_C) && \
@@ -2701,6 +2706,80 @@ exit:
}
/* END_CASE */
/* BEGIN_CASE depends_on:MBEDTLS_SSL_PROTO_TLS1_3:MBEDTLS_SSL_SESSION_TICKETS */
void ssl_tls13_session_load_rejects_bad_serialized_data(int endpoint_type,
int mutation)
{
mbedtls_ssl_session session, restored;
unsigned char *buf = NULL;
size_t len, bad_len, i;
unsigned char *field = NULL;
const unsigned char hostname[] = "hostname example";
const unsigned char alpn[] = "ALPNExample";
const unsigned char *string_to_corrupt = NULL;
size_t string_len = 0;
mbedtls_ssl_session_init(&session);
mbedtls_ssl_session_init(&restored);
USE_PSA_INIT();
TEST_EQUAL(mbedtls_test_ssl_tls13_populate_session(
&session, 42, endpoint_type), 0);
TEST_EQUAL(mbedtls_ssl_session_save(&session, NULL, 0, &len),
MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL);
TEST_CALLOC(buf, len + 1);
TEST_EQUAL(mbedtls_ssl_session_save(&session, buf, len, &len), 0);
/* The serialized data must load successfully before we corrupt it,
* otherwise the test below would not prove anything. */
TEST_EQUAL(mbedtls_ssl_session_load(&restored, buf, len), 0);
mbedtls_ssl_session_free(&restored);
mbedtls_ssl_session_init(&restored);
bad_len = len;
switch (mutation) {
case TEST_TLS13_SESSION_LOAD_TRAILING_DATA:
bad_len = len + 1;
buf[len] = 0;
break;
case TEST_TLS13_SESSION_LOAD_HOSTNAME_NO_NUL:
string_to_corrupt = hostname;
string_len = sizeof(hostname);
break;
case TEST_TLS13_SESSION_LOAD_ALPN_NO_NUL:
string_to_corrupt = alpn;
string_len = sizeof(alpn);
break;
default:
TEST_ASSERT(0);
}
if (string_to_corrupt != NULL) {
for (i = 0; i + string_len <= len; i++) {
if (memcmp(buf + i, string_to_corrupt, string_len) == 0) {
field = buf + i;
break;
}
}
TEST_ASSERT(field != NULL);
field[string_len - 1] = 'X';
}
TEST_EQUAL(mbedtls_ssl_session_load(&restored, buf, bad_len),
MBEDTLS_ERR_SSL_BAD_INPUT_DATA);
exit:
mbedtls_ssl_session_free(&session);
mbedtls_ssl_session_free(&restored);
mbedtls_free(buf);
USE_PSA_DONE();
}
/* END_CASE */
/* BEGIN_CASE */
void ssl_session_serialize_version_check(int corrupt_major,
int corrupt_minor,