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Merge 8acc73169850f6ca3bd6fdb86bd2e901006f3fdd into 3bb373867917b674265067cbd38b9d252c43d014

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4 changed files with 156 additions and 30 deletions
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4
ChangeLog.d/ssl-context-load-alpn-bounds.txt Normal file
View File

@ -0,0 +1,4 @@
Bugfix
* Reject serialized SSL contexts whose ALPN protocol length exceeds the
remaining serialized data, instead of reading past the end of the buffer
in mbedtls_ssl_context_load().

4
library/ssl_tls.c
View File

@ -5098,6 +5098,10 @@ static int ssl_context_load(mbedtls_ssl_context *ssl,
alpn_len = *p++;
if ((size_t) (end - p) < alpn_len) {
return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
}
if (alpn_len != 0 && ssl->conf->alpn_list != NULL) {
/* alpn_chosen should point to an item in the configured list */
for (cur = ssl->conf->alpn_list; *cur != NULL; cur++) {

8
tests/suites/test_suite_ssl.data
View File

@ -3055,8 +3055,12 @@ 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
SSL context serialization rejects out-of-bounds DTLS CID length
depends_on:MBEDTLS_SSL_HANDSHAKE_WITH_CERT_ENABLED:MBEDTLS_SSL_PROTO_TLS1_2:MBEDTLS_SSL_PROTO_DTLS:MBEDTLS_SSL_DTLS_CONNECTION_ID:MBEDTLS_SSL_CONTEXT_SERIALIZATION:PSA_HAVE_ALG_SOME_RSA_SIGN:PSA_WANT_ECC_SECP_R1_384:PSA_WANT_ALG_SHA_256:MBEDTLS_CAN_HANDLE_RSA_TEST_KEY:TEST_GCM_OR_CHACHAPOLY_ENABLED
ssl_context_load_rejects_oob_cid_length:
depends_on:MBEDTLS_SSL_DTLS_CONNECTION_ID
ssl_context_load_rejects_oob_length:TEST_SSL_CONTEXT_LOAD_OOB_CID
SSL context serialization rejects out-of-bounds ALPN length
depends_on:MBEDTLS_SSL_ALPN
ssl_context_load_rejects_oob_length:TEST_SSL_CONTEXT_LOAD_OOB_ALPN
Test configuration of EC groups through mbedtls_ssl_conf_groups()
conf_group:

170
tests/suites/test_suite_ssl.function
View File

@ -31,6 +31,10 @@
#define TEST_TLS13_SESSION_LOAD_HOSTNAME_NO_NUL 1
#define TEST_TLS13_SESSION_LOAD_ALPN_NO_NUL 2
/* Corrupted length fields for ssl_context_load_rejects_oob_length */
#define TEST_SSL_CONTEXT_LOAD_OOB_CID 0
#define TEST_SSL_CONTEXT_LOAD_OOB_ALPN 1
#if defined(MBEDTLS_SSL_PROTO_TLS1_2) && \
defined(MBEDTLS_SSL_SESSION_TICKETS) && \
defined(MBEDTLS_SSL_CLI_C) && defined(MBEDTLS_SSL_SRV_C) && \
@ -2992,9 +2996,10 @@ exit:
}
/* END_CASE */
/* BEGIN_CASE depends_on:MBEDTLS_SSL_HANDSHAKE_WITH_CERT_ENABLED:MBEDTLS_SSL_PROTO_TLS1_2:MBEDTLS_SSL_PROTO_DTLS:MBEDTLS_SSL_DTLS_CONNECTION_ID:MBEDTLS_SSL_CONTEXT_SERIALIZATION:PSA_HAVE_ALG_SOME_RSA_SIGN:PSA_WANT_ECC_SECP_R1_384:PSA_WANT_ALG_SHA_256:MBEDTLS_CAN_HANDLE_RSA_TEST_KEY:TEST_GCM_OR_CHACHAPOLY_ENABLED */
void ssl_context_load_rejects_oob_cid_length(void)
/* BEGIN_CASE depends_on:MBEDTLS_SSL_HANDSHAKE_WITH_CERT_ENABLED:MBEDTLS_SSL_PROTO_TLS1_2:MBEDTLS_SSL_PROTO_DTLS:MBEDTLS_SSL_CONTEXT_SERIALIZATION:PSA_HAVE_ALG_SOME_RSA_SIGN:PSA_WANT_ECC_SECP_R1_384:PSA_WANT_ALG_SHA_256:MBEDTLS_CAN_HANDLE_RSA_TEST_KEY:TEST_GCM_OR_CHACHAPOLY_ENABLED */
void ssl_context_load_rejects_oob_length(int field)
{
#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
/* Sentinel CID so we can find its location inside the serialized buffer. */
const unsigned char server_cid[] = {
0xAB, 0xCD, 0xEF, 0x12, 0x34, 0x56, 0x78, 0x9A
@ -3002,12 +3007,30 @@ void ssl_context_load_rejects_oob_cid_length(void)
const unsigned char client_cid[] = {
0x9A, 0x78, 0x56, 0x34, 0x12, 0xEF, 0xCD, 0xAB
};
#endif
#if defined(MBEDTLS_SSL_ALPN)
/* The negotiated protocol (alpn[0]) is the last field in the serialized
* context, so exactly strlen(alpn[0]) bytes remain after its length byte.
* On load, ssl_context_load() only memcmp()s configured protocols whose
* strlen() equals the length byte, so the corrupted length has to match a
* configured protocol to reach the memcmp(): alpn[1] is one character
* longer than alpn[0], which makes the corrupted length point exactly one
* byte past the end of the serialized data. It shares alpn[0]'s prefix so
* that all in-bounds bytes match and the memcmp() cannot stop before
* reading past the end of the buffer. */
const char negotiated[] = "alpnsentinel";
const char *alpn[] = { negotiated, "alpnsentinel2", NULL };
#endif
mbedtls_test_handshake_test_options options;
mbedtls_test_ssl_endpoint client_ep, server_ep;
unsigned char *context_buf = NULL;
size_t context_buf_len, i;
unsigned char *cid_len_p = NULL;
unsigned char *load_buf = NULL;
size_t context_buf_len, load_len, field_off, i;
const unsigned char *sentinel = NULL;
size_t sentinel_len = 0;
unsigned char corrupt_len = 0;
unsigned char *len_p = NULL;
memset(&client_ep, 0, sizeof(client_ep));
memset(&server_ep, 0, sizeof(server_ep));
@ -3023,23 +3046,66 @@ void ssl_context_load_rejects_oob_cid_length(void)
TEST_EQUAL(mbedtls_test_ssl_endpoint_init(
&server_ep, MBEDTLS_SSL_IS_SERVER, &options), 0);
/* Configure CID with unique patterns so we can locate the length byte in
* the serialized context. Both peers must agree on the CID length via
* conf_cid() before set_cid() will accept the value. */
TEST_EQUAL(mbedtls_ssl_conf_cid(&client_ep.conf, sizeof(client_cid),
MBEDTLS_SSL_UNEXPECTED_CID_FAIL), 0);
TEST_EQUAL(mbedtls_ssl_conf_cid(&server_ep.conf, sizeof(server_cid),
MBEDTLS_SSL_UNEXPECTED_CID_FAIL), 0);
TEST_EQUAL(mbedtls_ssl_set_cid(&client_ep.ssl, MBEDTLS_SSL_CID_ENABLED,
client_cid, sizeof(client_cid)), 0);
TEST_EQUAL(mbedtls_ssl_set_cid(&server_ep.ssl, MBEDTLS_SSL_CID_ENABLED,
server_cid, sizeof(server_cid)), 0);
switch (field) {
#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
case TEST_SSL_CONTEXT_LOAD_OOB_CID:
/* Configure CID with unique patterns so we can locate the length
* byte in the serialized context. Both peers must agree on the CID
* length via conf_cid() before set_cid() will accept the value. */
TEST_EQUAL(mbedtls_ssl_conf_cid(
&client_ep.conf, sizeof(client_cid),
MBEDTLS_SSL_UNEXPECTED_CID_FAIL), 0);
TEST_EQUAL(mbedtls_ssl_conf_cid(
&server_ep.conf, sizeof(server_cid),
MBEDTLS_SSL_UNEXPECTED_CID_FAIL), 0);
TEST_EQUAL(mbedtls_ssl_set_cid(
&client_ep.ssl, MBEDTLS_SSL_CID_ENABLED,
client_cid, sizeof(client_cid)), 0);
TEST_EQUAL(mbedtls_ssl_set_cid(
&server_ep.ssl, MBEDTLS_SSL_CID_ENABLED,
server_cid, sizeof(server_cid)), 0);
sentinel = server_cid;
sentinel_len = sizeof(server_cid);
/* The smallest length that overflows the in_cid array in the SSL
* transform, so the size check on that array, not the in-buffer
* bounds check before it, is what must reject the corrupted
* length. The loaded data gets the in_cid field grown to this
* many bytes (see the construction of load_buf below) so that
* the in-buffer bounds check indeed passes. */
corrupt_len = (unsigned char) (MBEDTLS_SSL_CID_IN_LEN_MAX + 1);
break;
#endif
#if defined(MBEDTLS_SSL_ALPN)
case TEST_SSL_CONTEXT_LOAD_OOB_ALPN:
/* Offer the same protocol list on both peers so alpn[0] is
* negotiated and serialized into the context. */
TEST_EQUAL(mbedtls_ssl_conf_alpn_protocols(&client_ep.conf, alpn),
0);
TEST_EQUAL(mbedtls_ssl_conf_alpn_protocols(&server_ep.conf, alpn),
0);
sentinel = (const unsigned char *) negotiated;
sentinel_len = strlen(negotiated);
/* One byte past the end of the serialized data; see the
* declaration of alpn[] above. */
corrupt_len = (unsigned char) strlen(alpn[1]);
break;
#endif
default:
TEST_ASSERT(0);
}
TEST_EQUAL(mbedtls_test_ssl_dtls_join_endpoints(&client_ep, &server_ep), 0);
TEST_ASSERT(mbedtls_test_ssl_perform_connection(&options, &client_ep,
&server_ep));
#if defined(MBEDTLS_SSL_ALPN)
if (field == TEST_SSL_CONTEXT_LOAD_OOB_ALPN) {
TEST_ASSERT(server_ep.ssl.alpn_chosen != NULL);
TEST_EQUAL(strcmp(server_ep.ssl.alpn_chosen, negotiated), 0);
}
#endif
/* Serialize the post-handshake server context. */
TEST_EQUAL(mbedtls_ssl_context_save(&server_ep.ssl, NULL, 0,
&context_buf_len),
@ -3048,29 +3114,76 @@ void ssl_context_load_rejects_oob_cid_length(void)
TEST_EQUAL(mbedtls_ssl_context_save(&server_ep.ssl, context_buf,
context_buf_len, &context_buf_len), 0);
/* The serialized format writes [in_cid_len][in_cid bytes]; locate the
* length byte by searching for our sentinel CID. */
for (i = 1; i + sizeof(server_cid) <= context_buf_len; i++) {
if (context_buf[i - 1] == (unsigned char) sizeof(server_cid) &&
memcmp(context_buf + i, server_cid, sizeof(server_cid)) == 0) {
cid_len_p = context_buf + i - 1;
/* Double-check that the serialized data loads cleanly before it gets
* corrupted. */
mbedtls_ssl_free(&server_ep.ssl);
mbedtls_ssl_init(&server_ep.ssl);
TEST_EQUAL(mbedtls_ssl_setup(&server_ep.ssl, &server_ep.conf), 0);
TEST_EQUAL(mbedtls_ssl_context_load(&server_ep.ssl, context_buf,
context_buf_len), 0);
/* Both fields are serialized as [length byte][data bytes]; locate the
* length byte by searching for the sentinel data. */
for (i = 1; i + sentinel_len <= context_buf_len; i++) {
if (context_buf[i - 1] == (unsigned char) sentinel_len &&
memcmp(context_buf + i, sentinel, sentinel_len) == 0) {
len_p = context_buf + i - 1;
break;
}
}
TEST_ASSERT(cid_len_p != NULL);
TEST_ASSERT(len_p != NULL);
/* Corrupt the length to the smallest value strictly greater than
* sizeof(in_cid), so we exercise the new bounds check rather than the
* pre-existing buffer-size check that would also trip on huge values. */
*cid_len_p = (unsigned char) (MBEDTLS_SSL_CID_IN_LEN_MAX + 1);
field_off = (size_t) (len_p + 1 - context_buf);
if (field == TEST_SSL_CONTEXT_LOAD_OOB_CID) {
/* The in_cid field sits in the middle of the serialized data, so a
* corrupted length cannot reach past the end of the buffer. Instead
* grow the field itself: keep its bytes, pad it to corrupt_len bytes
* and append the untouched rest of the serialized data, so that the
* in-buffer bounds check passes and the size check on the in_cid
* array is reached. */
load_len = context_buf_len + corrupt_len - sentinel_len;
TEST_CALLOC(load_buf, load_len);
memcpy(load_buf, context_buf, field_off + sentinel_len);
memset(load_buf + field_off + sentinel_len, 0xA5,
(size_t) corrupt_len - sentinel_len);
memcpy(load_buf + field_off + corrupt_len,
context_buf + field_off + sentinel_len,
context_buf_len - field_off - sentinel_len);
/* Double-check that corrupt_len bytes of field data plus the next
* length byte are present, which is what the in-buffer bounds check
* requires. */
TEST_ASSERT(load_len - field_off >= (size_t) corrupt_len + 1);
} else {
/* The ALPN field is the last one saved, so the buffer already ends
* right after it and the corrupted length reaches exactly one byte
* past the end. Load from a tightly allocated copy, so that reading
* even one byte past the end of the data overruns the allocation and
* gets caught by ASan or Valgrind. */
TEST_EQUAL((size_t) corrupt_len, context_buf_len - field_off + 1);
load_len = context_buf_len;
TEST_CALLOC(load_buf, load_len);
memcpy(load_buf, context_buf, load_len);
}
load_buf[field_off - 1] = corrupt_len;
/* Reinitialise the server SSL context so we can load into a fresh one. */
mbedtls_ssl_free(&server_ep.ssl);
mbedtls_ssl_init(&server_ep.ssl);
TEST_EQUAL(mbedtls_ssl_setup(&server_ep.ssl, &server_ep.conf), 0);
TEST_EQUAL(mbedtls_ssl_context_load(&server_ep.ssl, context_buf,
context_buf_len),
/* How a regression is caught differs between the two cases. In the ALPN
* case, without the bounds check the load still fails, because the
* out-of-bounds bytes are unlikely to match a configured protocol; what
* the missing check leaks is the out-of-bounds read in memcmp() itself,
* so that case catches a regression only when the test suite runs under
* ASan or Valgrind. In the CID case, without the size check the
* memcpy() overflows the in_cid array inside the SSL transform (which
* stays within the enclosing struct, invisible to ASan), the rest of
* the data then parses correctly aligned and the load succeeds, so the
* check below catches a regression on its own. */
TEST_EQUAL(mbedtls_ssl_context_load(&server_ep.ssl, load_buf, load_len),
MBEDTLS_ERR_SSL_BAD_INPUT_DATA);
exit:
@ -3078,6 +3191,7 @@ exit:
mbedtls_test_ssl_endpoint_free(&server_ep);
mbedtls_test_free_handshake_options(&options);
mbedtls_free(context_buf);
mbedtls_free(load_buf);
MD_OR_USE_PSA_DONE();
}
/* END_CASE */