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-rw-r--r--debian/patches/CVE-2017-7479.patch193
1 files changed, 193 insertions, 0 deletions
diff --git a/debian/patches/CVE-2017-7479.patch b/debian/patches/CVE-2017-7479.patch
new file mode 100644
index 0000000..9f75d31
--- /dev/null
+++ b/debian/patches/CVE-2017-7479.patch
@@ -0,0 +1,193 @@
+From ac08b27cfa693d9be592bb2597c260635aee9e68 Mon Sep 17 00:00:00 2001
+From: Steffan Karger <steffan.karger@fox-it.com>
+Date: Tue, 25 Apr 2017 10:00:44 +0200
+Subject: [PATCH 2/2] Drop packets instead of asserting out if packet id rolls
+ over
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Previously, if a mode was selected where packet ids are not allowed to roll
+over, but renegotiation does not succeed for some reason (e.g. no password
+entered in time, certificate expired or a malicious peer that refuses the
+renegotiaion on purpose) we would continue to use the old keys. Until the
+packet ID would roll over and we would ASSERT() out.
+
+Given that this can be triggered on purpose by an authenticated peer, this
+is a fix for an authenticated remote DoS vulnerability. An attack is
+rather inefficient though; a peer would need to get us to send 2^32
+packets (min-size packet is IP+UDP+OPCODE+PID+TAG (no payload), results in
+(20+8+1+4+16)×2^32 bytes, or approx. 196 GB).
+
+Signed-off-by: Steffan Karger <steffan.karger@fox-it.com>
+
+CVE-2017-7479
+
+---
+ src/openvpn/crypto.c | 25 ++++++++++++++++---------
+ src/openvpn/packet_id.c | 22 ++++++++++++++++------
+ src/openvpn/packet_id.h | 1 +
+ src/openvpn/tls_crypt.c | 6 +++++-
+ tests/unit_tests/openvpn/test_packet_id.c | 11 +++++++++--
+ 5 files changed, 47 insertions(+), 18 deletions(-)
+
+Index: openvpn-2.4.0/src/openvpn/crypto.c
+===================================================================
+--- openvpn-2.4.0.orig/src/openvpn/crypto.c
++++ openvpn-2.4.0/src/openvpn/crypto.c
+@@ -93,7 +93,11 @@ openvpn_encrypt_aead(struct buffer *buf,
+ buf_set_write(&iv_buffer, iv, iv_len);
+
+ /* IV starts with packet id to make the IV unique for packet */
+- ASSERT(packet_id_write(&opt->packet_id.send, &iv_buffer, false, false));
++ if (!packet_id_write(&opt->packet_id.send, &iv_buffer, false, false))
++ {
++ msg(D_CRYPT_ERRORS, "ENCRYPT ERROR: packet ID roll over");
++ goto err;
++ }
+
+ /* Remainder of IV consists of implicit part (unique per session) */
+ ASSERT(buf_write(&iv_buffer, ctx->implicit_iv, ctx->implicit_iv_len));
+@@ -194,11 +198,13 @@ openvpn_encrypt_v1(struct buffer *buf, s
+ }
+
+ /* Put packet ID in plaintext buffer */
+- if (packet_id_initialized(&opt->packet_id))
++ if (packet_id_initialized(&opt->packet_id)
++ && !packet_id_write(&opt->packet_id.send, buf,
++ opt->flags & CO_PACKET_ID_LONG_FORM,
++ true))
+ {
+- ASSERT(packet_id_write(&opt->packet_id.send, buf,
+- opt->flags & CO_PACKET_ID_LONG_FORM,
+- true));
++ msg(D_CRYPT_ERRORS, "ENCRYPT ERROR: packet ID roll over");
++ goto err;
+ }
+ }
+ else if (cipher_kt_mode_ofb_cfb(cipher_kt))
+@@ -258,11 +264,12 @@ openvpn_encrypt_v1(struct buffer *buf, s
+ }
+ else /* No Encryption */
+ {
+- if (packet_id_initialized(&opt->packet_id))
++ if (packet_id_initialized(&opt->packet_id)
++ && !packet_id_write(&opt->packet_id.send, buf,
++ opt->flags & CO_PACKET_ID_LONG_FORM, true))
+ {
+- ASSERT(packet_id_write(&opt->packet_id.send, buf,
+- BOOL_CAST(opt->flags & CO_PACKET_ID_LONG_FORM),
+- true));
++ msg(D_CRYPT_ERRORS, "ENCRYPT ERROR: packet ID roll over");
++ goto err;
+ }
+ if (ctx->hmac)
+ {
+Index: openvpn-2.4.0/src/openvpn/packet_id.c
+===================================================================
+--- openvpn-2.4.0.orig/src/openvpn/packet_id.c
++++ openvpn-2.4.0/src/openvpn/packet_id.c
+@@ -325,27 +325,37 @@ packet_id_read(struct packet_id_net *pin
+ return true;
+ }
+
+-static void
++static bool
+ packet_id_send_update(struct packet_id_send *p, bool long_form)
+ {
+ if (!p->time)
+ {
+ p->time = now;
+ }
+- p->id++;
+- if (!p->id)
++ if (p->id == PACKET_ID_MAX)
+ {
+- ASSERT(long_form);
++ /* Packet ID only allowed to roll over if using long form and time has
++ * moved forward since last roll over.
++ */
++ if (!long_form || now <= p->time)
++ {
++ return false;
++ }
+ p->time = now;
+- p->id = 1;
++ p->id = 0;
+ }
++ p->id++;
++ return true;
+ }
+
+ bool
+ packet_id_write(struct packet_id_send *p, struct buffer *buf, bool long_form,
+ bool prepend)
+ {
+- packet_id_send_update(p, long_form);
++ if (!packet_id_send_update(p, long_form))
++ {
++ return false;
++ }
+
+ const packet_id_type net_id = htonpid(p->id);
+ const net_time_t net_time = htontime(p->time);
+Index: openvpn-2.4.0/src/openvpn/packet_id.h
+===================================================================
+--- openvpn-2.4.0.orig/src/openvpn/packet_id.h
++++ openvpn-2.4.0/src/openvpn/packet_id.h
+@@ -50,6 +50,7 @@
+ * to for network transmission.
+ */
+ typedef uint32_t packet_id_type;
++#define PACKET_ID_MAX UINT32_MAX
+ typedef uint32_t net_time_t;
+
+ /*
+Index: openvpn-2.4.0/src/openvpn/tls_crypt.c
+===================================================================
+--- openvpn-2.4.0.orig/src/openvpn/tls_crypt.c
++++ openvpn-2.4.0/src/openvpn/tls_crypt.c
+@@ -95,7 +95,11 @@ tls_crypt_wrap(const struct buffer *src,
+ format_hex(BPTR(src), BLEN(src), 80, &gc));
+
+ /* Get packet ID */
+- ASSERT(packet_id_write(&opt->packet_id.send, dst, true, false));
++ if (!packet_id_write(&opt->packet_id.send, dst, true, false))
++ {
++ msg(D_CRYPT_ERRORS, "TLS-CRYPT ERROR: packet ID roll over.");
++ goto err;
++ }
+
+ dmsg(D_PACKET_CONTENT, "TLS-CRYPT WRAP AD: %s",
+ format_hex(BPTR(dst), BLEN(dst), 0, &gc));
+Index: openvpn-2.4.0/tests/unit_tests/openvpn/test_packet_id.c
+===================================================================
+--- openvpn-2.4.0.orig/tests/unit_tests/openvpn/test_packet_id.c
++++ openvpn-2.4.0/tests/unit_tests/openvpn/test_packet_id.c
+@@ -129,8 +129,7 @@ test_packet_id_write_short_wrap(void **s
+ struct test_packet_id_write_data *data = *state;
+
+ data->pis.id = ~0;
+- expect_assert_failure(
+- packet_id_write(&data->pis, &data->test_buf, false, false));
++ assert_false(packet_id_write(&data->pis, &data->test_buf, false, false));
+ }
+
+ static void
+@@ -139,8 +138,16 @@ test_packet_id_write_long_wrap(void **st
+ struct test_packet_id_write_data *data = *state;
+
+ data->pis.id = ~0;
++ data->pis.time = 5006;
++
++ /* Write fails if time did not change */
++ now = 5006;
++ assert_false(packet_id_write(&data->pis, &data->test_buf, true, false));
++
++ /* Write succeeds if time moved forward */
+ now = 5010;
+ assert_true(packet_id_write(&data->pis, &data->test_buf, true, false));
++
+ assert(data->pis.id == 1);
+ assert(data->pis.time == now);
+ assert_true(data->test_buf_data.buf_id == htonl(1));
generated by cgit v1.2.3 (git 2.25.1) at 2024-05-22 15:01:28 +0000