openssl-3/openssl-CVE-2024-5535.patch

From 4ada436a1946cbb24db5ab4ca082b69c1bc10f37 Mon Sep 17 00:00:00 2001
From: Matt Caswell <matt@openssl.org>
Date: Fri, 31 May 2024 11:14:33 +0100
Subject: [PATCH] Fix SSL_select_next_proto

Ensure that the provided client list is non-NULL and starts with a valid
entry. When called from the ALPN callback the client list should already
have been validated by OpenSSL so this should not cause a problem. When
called from the NPN callback the client list is locally configured and
will not have already been validated. Therefore SSL_select_next_proto
should not assume that it is correctly formatted.

We implement stricter checking of the client protocol list. We also do the
same for the server list while we are about it.

CVE-2024-5535

Reviewed-by: Neil Horman <nhorman@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/24718)
---
 ssl/ssl_lib.c | 63 ++++++++++++++++++++++++++++++++-------------------
 1 file changed, 40 insertions(+), 23 deletions(-)

diff --git a/ssl/ssl_lib.c b/ssl/ssl_lib.c
index 5493d9b9c7..f218dcf1db 100644
--- a/ssl/ssl_lib.c
+++ b/ssl/ssl_lib.c
@@ -2953,37 +2953,54 @@ int SSL_select_next_proto(unsigned char **out, unsigned char *outlen,
                           unsigned int server_len,
                           const unsigned char *client, unsigned int client_len)
 {
-    unsigned int i, j;
-    const unsigned char *result;
-    int status = OPENSSL_NPN_UNSUPPORTED;
+    PACKET cpkt, csubpkt, spkt, ssubpkt;
+
+    if (!PACKET_buf_init(&cpkt, client, client_len)
+            || !PACKET_get_length_prefixed_1(&cpkt, &csubpkt)
+            || PACKET_remaining(&csubpkt) == 0) {
+        *out = NULL;
+        *outlen = 0;
+        return OPENSSL_NPN_NO_OVERLAP;
+    }
+
+    /*
+     * Set the default opportunistic protocol. Will be overwritten if we find
+     * a match.
+     */
+    *out = (unsigned char *)PACKET_data(&csubpkt);
+    *outlen = (unsigned char)PACKET_remaining(&csubpkt);
 
     /*
      * For each protocol in server preference order, see if we support it.
      */
-    for (i = 0; i < server_len;) {
-        for (j = 0; j < client_len;) {
-            if (server[i] == client[j] &&
-                memcmp(&server[i + 1], &client[j + 1], server[i]) == 0) {
-                /* We found a match */
-                result = &server[i];
-                status = OPENSSL_NPN_NEGOTIATED;
-                goto found;
+    if (PACKET_buf_init(&spkt, server, server_len)) {
+        while (PACKET_get_length_prefixed_1(&spkt, &ssubpkt)) {
+            if (PACKET_remaining(&ssubpkt) == 0)
+                continue; /* Invalid - ignore it */
+            if (PACKET_buf_init(&cpkt, client, client_len)) {
+                while (PACKET_get_length_prefixed_1(&cpkt, &csubpkt)) {
+                    if (PACKET_equal(&csubpkt, PACKET_data(&ssubpkt),
+                                     PACKET_remaining(&ssubpkt))) {
+                        /* We found a match */
+                        *out = (unsigned char *)PACKET_data(&ssubpkt);
+                        *outlen = (unsigned char)PACKET_remaining(&ssubpkt);
+                        return OPENSSL_NPN_NEGOTIATED;
+                    }
+                }
+                /* Ignore spurious trailing bytes in the client list */
+            } else {
+                /* This should never happen */
+                return OPENSSL_NPN_NO_OVERLAP;
             }
-            j += client[j];
-            j++;
         }
-        i += server[i];
-        i++;
+        /* Ignore spurious trailing bytes in the server list */
     }
 
-    /* There's no overlap between our protocols and the server's list. */
-    result = client;
-    status = OPENSSL_NPN_NO_OVERLAP;
-
- found:
-    *out = (unsigned char *)result + 1;
-    *outlen = result[0];
-    return status;
+    /*
+     * There's no overlap between our protocols and the server's list. We use
+     * the default opportunistic protocol selected earlier
+     */
+    return OPENSSL_NPN_NO_OVERLAP;
 }
 
 #ifndef OPENSSL_NO_NEXTPROTONEG
-- 
2.45.2

From 4279c89a726025c758db3dafb263b17e52211304 Mon Sep 17 00:00:00 2001
From: Matt Caswell <matt@openssl.org>
Date: Fri, 31 May 2024 11:18:27 +0100
Subject: [PATCH] More correctly handle a selected_len of 0 when
 processing NPN

In the case where the NPN callback returns with SSL_TLEXT_ERR_OK, but
the selected_len is 0 we should fail. Previously this would fail with an
internal_error alert because calling OPENSSL_malloc(selected_len) will
return NULL when selected_len is 0. We make this error detection more
explicit and return a handshake failure alert.

Follow on from CVE-2024-5535

Reviewed-by: Neil Horman <nhorman@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/24718)
---
 ssl/statem/extensions_clnt.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/ssl/statem/extensions_clnt.c b/ssl/statem/extensions_clnt.c
index 842be0722b..a07dc62e9a 100644
--- a/ssl/statem/extensions_clnt.c
+++ b/ssl/statem/extensions_clnt.c
@@ -1536,7 +1536,8 @@ int tls_parse_stoc_npn(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
                                   PACKET_data(pkt),
                                   PACKET_remaining(pkt),
                                   s->ctx->ext.npn_select_cb_arg) !=
-             SSL_TLSEXT_ERR_OK) {
+                                  SSL_TLSEXT_ERR_OK
+            || selected_len == 0) {
         SSLfatal(s, SSL_AD_HANDSHAKE_FAILURE, SSL_R_BAD_EXTENSION);
         return 0;
     }
-- 
2.45.2

From 889ed19ba25abebd2690997acd6d4791cbe5c493 Mon Sep 17 00:00:00 2001
From: Matt Caswell <matt@openssl.org>
Date: Fri, 31 May 2024 11:46:38 +0100
Subject: [PATCH] Clarify the SSL_select_next_proto() documentation

We clarify the input preconditions and the expected behaviour in the event
of no overlap.

Follow on from CVE-2024-5535

Reviewed-by: Neil Horman <nhorman@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/24718)
---
 doc/man3/SSL_CTX_set_alpn_select_cb.pod | 26 +++++++++++++++++--------
 1 file changed, 18 insertions(+), 8 deletions(-)

diff --git a/doc/man3/SSL_CTX_set_alpn_select_cb.pod b/doc/man3/SSL_CTX_set_alpn_select_cb.pod
index 102e657851..a29557dd91 100644
--- a/doc/man3/SSL_CTX_set_alpn_select_cb.pod
+++ b/doc/man3/SSL_CTX_set_alpn_select_cb.pod
@@ -52,7 +52,8 @@ SSL_select_next_proto, SSL_get0_alpn_selected, SSL_get0_next_proto_negotiated
 SSL_CTX_set_alpn_protos() and SSL_set_alpn_protos() are used by the client to
 set the list of protocols available to be negotiated. The B<protos> must be in
 protocol-list format, described below. The length of B<protos> is specified in
-B<protos_len>.
+B<protos_len>. Setting B<protos_len> to 0 clears any existing list of ALPN
+protocols and no ALPN extension will be sent to the server.
 
 SSL_CTX_set_alpn_select_cb() sets the application callback B<cb> used by a
 server to select which protocol to use for the incoming connection. When B<cb>
@@ -73,9 +74,16 @@ B<server_len> and B<client>, B<client_len> must be in the protocol-list format
 described below. The first item in the B<server>, B<server_len> list that
 matches an item in the B<client>, B<client_len> list is selected, and returned
 in B<out>, B<outlen>. The B<out> value will point into either B<server> or
-B<client>, so it should be copied immediately. If no match is found, the first
-item in B<client>, B<client_len> is returned in B<out>, B<outlen>. This
-function can also be used in the NPN callback.
+B<client>, so it should be copied immediately. The client list must include at
+least one valid (nonempty) protocol entry in the list.
+
+The SSL_select_next_proto() helper function can be useful from either the ALPN
+callback or the NPN callback (described below). If no match is found, the first
+item in B<client>, B<client_len> is returned in B<out>, B<outlen> and
+B<OPENSSL_NPN_NO_OVERLAP> is returned. This can be useful when implementating
+the NPN callback. In the ALPN case, the value returned in B<out> and B<outlen>
+must be ignored if B<OPENSSL_NPN_NO_OVERLAP> has been returned from
+SSL_select_next_proto().
 
 SSL_CTX_set_next_proto_select_cb() sets a callback B<cb> that is called when a
 client needs to select a protocol from the server's provided list, and a
@@ -85,9 +93,10 @@ must be set to point to the selected protocol (which may be within B<in>).
 The length of the protocol name must be written into B<outlen>. The
 server's advertised protocols are provided in B<in> and B<inlen>. The
 callback can assume that B<in> is syntactically valid. The client must
-select a protocol. It is fatal to the connection if this callback returns
-a value other than B<SSL_TLSEXT_ERR_OK>. The B<arg> parameter is the pointer
-set via SSL_CTX_set_next_proto_select_cb().
+select a protocol (although it may be an empty, zero length protocol). It is
+fatal to the connection if this callback returns a value other than
+B<SSL_TLSEXT_ERR_OK> or if the zero length protocol is selected. The B<arg>
+parameter is the pointer set via SSL_CTX_set_next_proto_select_cb().
 
 SSL_CTX_set_next_protos_advertised_cb() sets a callback B<cb> that is called
 when a TLS server needs a list of supported protocols for Next Protocol
@@ -149,7 +158,8 @@ A match was found and is returned in B<out>, B<outlen>.
 =item OPENSSL_NPN_NO_OVERLAP
 
 No match was found. The first item in B<client>, B<client_len> is returned in
-B<out>, B<outlen>.
+B<out>, B<outlen> (or B<NULL> and 0 in the case where the first entry in
+B<client> is invalid).
 
 =back
 
-- 
2.45.2

From 087501b4f572825e27ca8cc2c5874fcf6fd47cf7 Mon Sep 17 00:00:00 2001
From: Matt Caswell <matt@openssl.org>
Date: Fri, 21 Jun 2024 10:41:55 +0100
Subject: [PATCH] Correct return values for
 tls_construct_stoc_next_proto_neg

Return EXT_RETURN_NOT_SENT in the event that we don't send the extension,
rather than EXT_RETURN_SENT. This actually makes no difference at all to
the current control flow since this return value is ignored in this case
anyway. But lets make it correct anyway.

Follow on from CVE-2024-5535

Reviewed-by: Neil Horman <nhorman@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/24718)
---
 ssl/statem/extensions_srvr.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/ssl/statem/extensions_srvr.c b/ssl/statem/extensions_srvr.c
index 4ea085e1a1..2da880450f 100644
--- a/ssl/statem/extensions_srvr.c
+++ b/ssl/statem/extensions_srvr.c
@@ -1476,9 +1476,10 @@ EXT_RETURN tls_construct_stoc_next_proto_neg(SSL *s, WPACKET *pkt,
             return EXT_RETURN_FAIL;
         }
         s->s3.npn_seen = 1;
+        return EXT_RETURN_SENT;
     }
 
-    return EXT_RETURN_SENT;
+    return EXT_RETURN_NOT_SENT;
 }
 #endif
 
-- 
2.45.2

From 017e54183b95617825fb9316d618c154a34c634e Mon Sep 17 00:00:00 2001
From: Matt Caswell <matt@openssl.org>
Date: Fri, 21 Jun 2024 11:51:54 +0100
Subject: [PATCH] Add ALPN validation in the client

The ALPN protocol selected by the server must be one that we originally
advertised. We should verify that it is.

Follow on from CVE-2024-5535

Reviewed-by: Neil Horman <nhorman@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/24718)
---
 ssl/statem/extensions_clnt.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/ssl/statem/extensions_clnt.c b/ssl/statem/extensions_clnt.c
index a07dc62e9a..b21ccf9273 100644
--- a/ssl/statem/extensions_clnt.c
+++ b/ssl/statem/extensions_clnt.c
@@ -1566,6 +1566,8 @@ int tls_parse_stoc_alpn(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
                         size_t chainidx)
 {
     size_t len;
+    PACKET confpkt, protpkt;
+    int valid = 0;
 
     /* We must have requested it. */
     if (!s->s3.alpn_sent) {
@@ -1584,6 +1586,28 @@ int tls_parse_stoc_alpn(SSL *s, PACKET *pkt, unsigned int context, X509 *x,
         SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_R_BAD_EXTENSION);
         return 0;
     }
+
+    /* It must be a protocol that we sent */
+    if (!PACKET_buf_init(&confpkt, s->ext.alpn, s->ext.alpn_len)) {
+        SSLfatal(s, SSL_AD_INTERNAL_ERROR, ERR_R_INTERNAL_ERROR);
+        return 0;
+    }
+    while (PACKET_get_length_prefixed_1(&confpkt, &protpkt)) {
+        if (PACKET_remaining(&protpkt) != len)
+            continue;
+        if (memcmp(PACKET_data(pkt), PACKET_data(&protpkt), len) == 0) {
+            /* Valid protocol found */
+            valid = 1;
+            break;
+        }
+    }
+
+    if (!valid) {
+        /* The protocol sent from the server does not match one we advertised */
+        SSLfatal(s, SSL_AD_DECODE_ERROR, SSL_R_BAD_EXTENSION);
+        return 0;
+    }
+
     OPENSSL_free(s->s3.alpn_selected);
     s->s3.alpn_selected = OPENSSL_malloc(len);
     if (s->s3.alpn_selected == NULL) {
-- 
2.45.2