The branch master has been updated
via 163b8016160f03558d8352b76fb594685cb39f7d (commit)
from 1c9761d0b547d2d135037d215cd16feb4d0b698c (commit)
- Log -----------------------------------------------------------------
commit 163b8016160f03558d8352b76fb594685cb39f7d
Author: Martin Elshuber <martin.elshu...@theobroma-systems.com>
Date: Tue Jun 23 12:14:41 2020 +0200
Add support to zeroize plaintext in S3 record layer
Some applications want even all plaintext copies beeing
zeroized. However, currently plaintext residuals are kept in rbuf
within the s3 record layer.
This patch add the option SSL_OP_CLEANSE_PLAINTEXT to its friends to
optionally enable cleansing of decrypted plaintext data.
Reviewed-by: Matt Caswell <m...@openssl.org>
Reviewed-by: Shane Lontis <shane.lon...@oracle.com>
Reviewed-by: Dmitry Belyavskiy <beld...@gmail.com>
(Merged from https://github.com/openssl/openssl/pull/12251)
-----------------------------------------------------------------------
Summary of changes:
CHANGES.md | 8 +++
doc/man3/SSL_CTX_set_options.pod | 14 +++++
include/openssl/ssl.h | 3 +-
ssl/record/rec_layer_d1.c | 6 +++
ssl/record/rec_layer_s3.c | 2 +
ssl/record/ssl3_buffer.c | 2 +
test/sslapitest.c | 114 +++++++++++++++++++++++++++++++++++++++
7 files changed, 148 insertions(+), 1 deletion(-)
diff --git a/CHANGES.md b/CHANGES.md
index 2cb73985a3..4e0002f668 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1100,6 +1100,14 @@ OpenSSL 3.0
*Boris Pismenny*
+ * The SSL option SSL_OP_CLEANSE_PLAINTEXT is introduced. If that
+ option is set, openssl cleanses (zeroize) plaintext bytes from
+ internal buffers after delivering them to the application. Note,
+ the application is still responsible for cleansing other copies
+ (e.g.: data received by SSL_read(3)).
+
+ *Martin Elshuber*
+
OpenSSL 1.1.1
-------------
diff --git a/doc/man3/SSL_CTX_set_options.pod b/doc/man3/SSL_CTX_set_options.pod
index 1bf19ecd23..adc646d72d 100644
--- a/doc/man3/SSL_CTX_set_options.pod
+++ b/doc/man3/SSL_CTX_set_options.pod
@@ -265,6 +265,20 @@ functionality is not required. Those applications can turn
this feature off by
setting this option. This is a server-side opton only. It is ignored by
clients.
+=item SSL_OP_CLEANSE_PLAINTEXT
+
+By default TLS connections keep a copy of received plaintext
+application data in a static buffer until it is overwritten by the
+next portion of data. When enabling SSL_OP_CLEANSE_PLAINTEXT
+deciphered application data is cleansed by calling OPENSSL_cleanse(3)
+after passing data to the application. Data is also cleansed when
+releasing the connection (eg. L<SSL_free(3)>).
+
+Since OpenSSL only cleanses internal buffers, the application is still
+responsible for cleansing all other buffers. Most notably, this
+applies to buffers passed to functions like L<SSL_read(3)>,
+L<SSL_peek(3)> but also like L<SSL_write(3)>.
+
=back
The following options no longer have any effect but their identifiers are
diff --git a/include/openssl/ssl.h b/include/openssl/ssl.h
index f855f9470d..8d96f0d85a 100644
--- a/include/openssl/ssl.h
+++ b/include/openssl/ssl.h
@@ -321,7 +321,8 @@ typedef int (*SSL_async_callback_fn)(SSL *s, void *arg);
/* Disable Extended master secret */
# define SSL_OP_NO_EXTENDED_MASTER_SECRET 0x00000001U
-/* Reserved value (until OpenSSL 3.0.0) 0x00000002U */
+/* Cleanse plaintext copies of data delivered to the application */
+# define SSL_OP_CLEANSE_PLAINTEXT 0x00000002U
/* Allow initial connection to servers that don't support RI */
# define SSL_OP_LEGACY_SERVER_CONNECT 0x00000004U
diff --git a/ssl/record/rec_layer_d1.c b/ssl/record/rec_layer_d1.c
index 866ef18381..0da012fdfd 100644
--- a/ssl/record/rec_layer_d1.c
+++ b/ssl/record/rec_layer_d1.c
@@ -74,6 +74,8 @@ void DTLS_RECORD_LAYER_clear(RECORD_LAYER *rl)
while ((item = pqueue_pop(d->processed_rcds.q)) != NULL) {
rdata = (DTLS1_RECORD_DATA *)item->data;
+ if (rl->s->options & SSL_OP_CLEANSE_PLAINTEXT)
+ OPENSSL_cleanse(rdata->rbuf.buf, rdata->rbuf.len);
OPENSSL_free(rdata->rbuf.buf);
OPENSSL_free(item->data);
pitem_free(item);
@@ -81,6 +83,8 @@ void DTLS_RECORD_LAYER_clear(RECORD_LAYER *rl)
while ((item = pqueue_pop(d->buffered_app_data.q)) != NULL) {
rdata = (DTLS1_RECORD_DATA *)item->data;
+ if (rl->s->options & SSL_OP_CLEANSE_PLAINTEXT)
+ OPENSSL_cleanse(rdata->rbuf.buf, rdata->rbuf.len);
OPENSSL_free(rdata->rbuf.buf);
OPENSSL_free(item->data);
pitem_free(item);
@@ -514,6 +518,8 @@ int dtls1_read_bytes(SSL *s, int type, int *recvd_type,
unsigned char *buf,
if (SSL3_RECORD_get_length(rr) == 0)
SSL3_RECORD_set_read(rr);
} else {
+ if (s->options & SSL_OP_CLEANSE_PLAINTEXT)
+
OPENSSL_cleanse(&(SSL3_RECORD_get_data(rr)[SSL3_RECORD_get_off(rr)]), n);
SSL3_RECORD_sub_length(rr, n);
SSL3_RECORD_add_off(rr, n);
if (SSL3_RECORD_get_length(rr) == 0) {
diff --git a/ssl/record/rec_layer_s3.c b/ssl/record/rec_layer_s3.c
index 8ea16672b6..1d9e803570 100644
--- a/ssl/record/rec_layer_s3.c
+++ b/ssl/record/rec_layer_s3.c
@@ -1484,6 +1484,8 @@ int ssl3_read_bytes(SSL *s, int type, int *recvd_type,
unsigned char *buf,
if (SSL3_RECORD_get_length(rr) == 0)
SSL3_RECORD_set_read(rr);
} else {
+ if (s->options & SSL_OP_CLEANSE_PLAINTEXT)
+ OPENSSL_cleanse(&(rr->data[rr->off]), n);
SSL3_RECORD_sub_length(rr, n);
SSL3_RECORD_add_off(rr, n);
if (SSL3_RECORD_get_length(rr) == 0) {
diff --git a/ssl/record/ssl3_buffer.c b/ssl/record/ssl3_buffer.c
index 2c25099e10..4ebb478ab2 100644
--- a/ssl/record/ssl3_buffer.c
+++ b/ssl/record/ssl3_buffer.c
@@ -180,6 +180,8 @@ int ssl3_release_read_buffer(SSL *s)
SSL3_BUFFER *b;
b = RECORD_LAYER_get_rbuf(&s->rlayer);
+ if (s->options & SSL_OP_CLEANSE_PLAINTEXT)
+ OPENSSL_cleanse(b->buf, b->len);
OPENSSL_free(b->buf);
b->buf = NULL;
return 1;
diff --git a/test/sslapitest.c b/test/sslapitest.c
index 30dcae3fb1..182984ecb1 100644
--- a/test/sslapitest.c
+++ b/test/sslapitest.c
@@ -1595,6 +1595,119 @@ static int test_large_message_dtls(void)
}
#endif
+static int execute_cleanse_plaintext(const SSL_METHOD *smeth,
+ const SSL_METHOD *cmeth,
+ int min_version, int max_version)
+{
+ size_t i;
+ SSL_CTX *cctx = NULL, *sctx = NULL;
+ SSL *clientssl = NULL, *serverssl = NULL;
+ int testresult = 0;
+ SSL3_RECORD *rr;
+ void *zbuf;
+
+ static unsigned char cbuf[16000];
+ static unsigned char sbuf[16000];
+
+ if (!TEST_true(create_ssl_ctx_pair(libctx,
+ smeth, cmeth,
+ min_version, max_version,
+ &sctx, &cctx, cert,
+ privkey)))
+ goto end;
+
+ if (!TEST_true(create_ssl_objects(sctx, cctx, &serverssl, &clientssl,
+ NULL, NULL)))
+ goto end;
+
+ if (!TEST_true(SSL_set_options(serverssl, SSL_OP_CLEANSE_PLAINTEXT)))
+ goto end;
+
+ if (!TEST_true(create_ssl_connection(serverssl, clientssl,
+ SSL_ERROR_NONE)))
+ goto end;
+
+ for (i = 0; i < sizeof(cbuf); i++) {
+ cbuf[i] = i & 0xff;
+ }
+
+ if (!TEST_int_eq(SSL_write(clientssl, cbuf, sizeof(cbuf)), sizeof(cbuf)))
+ goto end;
+
+ if (!TEST_int_eq(SSL_peek(serverssl, &sbuf, sizeof(sbuf)), sizeof(sbuf)))
+ goto end;
+
+ if (!TEST_mem_eq(cbuf, sizeof(cbuf), sbuf, sizeof(sbuf)))
+ goto end;
+
+ /*
+ * Since we called SSL_peek(), we know the data in the record
+ * layer is a plaintext record. We can gather the pointer to check
+ * for zeroization after SSL_read().
+ */
+ rr = serverssl->rlayer.rrec;
+ zbuf = &rr->data[rr->off];
+ if (!TEST_int_eq(rr->length, sizeof(cbuf)))
+ goto end;
+
+ /*
+ * After SSL_peek() the plaintext must still be stored in the
+ * record.
+ */
+ if (!TEST_mem_eq(cbuf, sizeof(cbuf), zbuf, sizeof(cbuf)))
+ goto end;
+
+ memset(sbuf, 0, sizeof(sbuf));
+ if (!TEST_int_eq(SSL_read(serverssl, &sbuf, sizeof(sbuf)), sizeof(sbuf)))
+ goto end;
+
+ if (!TEST_mem_eq(cbuf, sizeof(cbuf), sbuf, sizeof(cbuf)))
+ goto end;
+
+ /* Check if rbuf is cleansed */
+ memset(cbuf, 0, sizeof(cbuf));
+ if (!TEST_mem_eq(cbuf, sizeof(cbuf), zbuf, sizeof(cbuf)))
+ goto end;
+
+ testresult = 1;
+ end:
+ SSL_free(serverssl);
+ SSL_free(clientssl);
+ SSL_CTX_free(sctx);
+ SSL_CTX_free(cctx);
+
+ return testresult;
+}
+
+static int test_cleanse_plaintext(void)
+{
+#if !defined(OPENSSL_NO_TLS1_2)
+ if (!TEST_true(execute_cleanse_plaintext(TLS_server_method(),
+ TLS_client_method(),
+ TLS1_2_VERSION,
+ TLS1_2_VERSION)))
+ return 0;
+
+#endif
+
+#if !defined(OPENSSL_NO_TLS1_3)
+ if (!TEST_true(execute_cleanse_plaintext(TLS_server_method(),
+ TLS_client_method(),
+ TLS1_3_VERSION,
+ TLS1_3_VERSION)))
+ return 0;
+#endif
+
+#if !defined(OPENSSL_NO_DTLS)
+ if (!TEST_true(execute_cleanse_plaintext(DTLS_server_method(),
+ DTLS_client_method(),
+ DTLS1_VERSION,
+ 0)))
+ return 0;
+#endif
+ return 1;
+}
+
#ifndef OPENSSL_NO_OCSP
static int ocsp_server_cb(SSL *s, void *arg)
{
@@ -8324,6 +8437,7 @@ int setup_tests(void)
#ifndef OPENSSL_NO_DTLS
ADD_TEST(test_large_message_dtls);
#endif
+ ADD_TEST(test_cleanse_plaintext);
#ifndef OPENSSL_NO_OCSP
ADD_TEST(test_tlsext_status_type);
#endif
