v1-0001-Use-BIO_-get-set-_app_data-instead-of-BIO_-get-se.patch

From 672103a67aaf0dae5be6c5adcc5ce19e5b6d7676 Mon Sep 17 00:00:00 2001
From: Tristan Partin <tristan@neon.tech>
Date: Mon, 27 Nov 2023 11:49:52 -0600
Subject: [PATCH v1] Use BIO_{get,set}_app_data() instead of
 BIO_{get,set}_data()

Compiling Postgres against OpenSSL 3.2 exposed a regression:

$ psql "postgresql://$DB?sslmode=require"
psql: error: connection to server at "redacted" (redacted), port 5432 failed: ERROR:  Parameter 'user' is missing in startup packet.
double free or corruption (out)
Aborted (core dumped)

Analyzing the backtrace, openssl was overwriting heap-allocated data in
our PGconn struct because it thought BIO::ptr was a struct bss_sock_st
*. OpenSSL then called a memset() on a member of that struct, and we
zeroed out data in our PGconn struct.

BIO_get_data(3) says the following:

> These functions are mainly useful when implementing a custom BIO.
>
> The BIO_set_data() function associates the custom data pointed to by ptr
> with the BIO a. This data can subsequently be retrieved via a call to
> BIO_get_data(). This can be used by custom BIOs for storing
> implementation specific information.

If you take a look at my_BIO_s_socket(), we create a partially custom
BIO, but for the most part are defaulting to the methods defined by
BIO_s_socket(). We need to set application-specific data and not BIO
private data, so that the BIO implementation we rely on, can properly
assert that its private data is what it expects.

Co-authored-by: Bo Andreson <mail@boanderson.me>
---
 meson.build                              |  1 -
 src/backend/libpq/be-secure-openssl.c    | 11 +++--------
 src/include/pg_config.h.in               |  3 ---
 src/interfaces/libpq/fe-secure-openssl.c | 20 +++-----------------
 src/tools/msvc/Solution.pm               |  2 --
 5 files changed, 6 insertions(+), 31 deletions(-)

diff --git a/meson.build b/meson.build
index ee58ee7a06..0095fb183a 100644
--- a/meson.build
+++ b/meson.build
@@ -1285,7 +1285,6 @@ if sslopt in ['auto', 'openssl']
       # doesn't have these OpenSSL 1.1.0 functions. So check for individual
       # functions.
       ['OPENSSL_init_ssl'],
-      ['BIO_get_data'],
       ['BIO_meth_new'],
       ['ASN1_STRING_get0_data'],
       ['HMAC_CTX_new'],
diff --git a/src/backend/libpq/be-secure-openssl.c b/src/backend/libpq/be-secure-openssl.c
index 31b6a6eacd..1b8b32c5b3 100644
--- a/src/backend/libpq/be-secure-openssl.c
+++ b/src/backend/libpq/be-secure-openssl.c
@@ -842,11 +842,6 @@ be_tls_write(Port *port, void *ptr, size_t len, int *waitfor)
  * see sock_read() and sock_write() in OpenSSL's crypto/bio/bss_sock.c.
  */
 
-#ifndef HAVE_BIO_GET_DATA
-#define BIO_get_data(bio) (bio->ptr)
-#define BIO_set_data(bio, data) (bio->ptr = data)
-#endif
-
 static BIO_METHOD *my_bio_methods = NULL;
 
 static int
@@ -856,7 +851,7 @@ my_sock_read(BIO *h, char *buf, int size)
 
 	if (buf != NULL)
 	{
-		res = secure_raw_read(((Port *) BIO_get_data(h)), buf, size);
+		res = secure_raw_read(((Port *) BIO_get_app_data(h)), buf, size);
 		BIO_clear_retry_flags(h);
 		if (res <= 0)
 		{
@@ -876,7 +871,7 @@ my_sock_write(BIO *h, const char *buf, int size)
 {
 	int			res = 0;
 
-	res = secure_raw_write(((Port *) BIO_get_data(h)), buf, size);
+	res = secure_raw_write(((Port *) BIO_get_app_data(h)), buf, size);
 	BIO_clear_retry_flags(h);
 	if (res <= 0)
 	{
@@ -952,7 +947,7 @@ my_SSL_set_fd(Port *port, int fd)
 		SSLerr(SSL_F_SSL_SET_FD, ERR_R_BUF_LIB);
 		goto err;
 	}
-	BIO_set_data(bio, port);
+	BIO_set_app_data(bio, port);
 
 	BIO_set_fd(bio, fd, BIO_NOCLOSE);
 	SSL_set_bio(port->ssl, bio, bio);
diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in
index d8a2985567..5f16918243 100644
--- a/src/include/pg_config.h.in
+++ b/src/include/pg_config.h.in
@@ -66,9 +66,6 @@
 /* Define to 1 if you have the `backtrace_symbols' function. */
 #undef HAVE_BACKTRACE_SYMBOLS
 
-/* Define to 1 if you have the `BIO_get_data' function. */
-#undef HAVE_BIO_GET_DATA
-
 /* Define to 1 if you have the `BIO_meth_new' function. */
 #undef HAVE_BIO_METH_NEW
 
diff --git a/src/interfaces/libpq/fe-secure-openssl.c b/src/interfaces/libpq/fe-secure-openssl.c
index 4aeaf08312..dc5aa79fe8 100644
--- a/src/interfaces/libpq/fe-secure-openssl.c
+++ b/src/interfaces/libpq/fe-secure-openssl.c
@@ -1806,20 +1806,6 @@ PQsslAttribute(PGconn *conn, const char *attribute_name)
 	return NULL;				/* unknown attribute */
 }
 
-/*
- * Private substitute BIO: this does the sending and receiving using
- * pqsecure_raw_write() and pqsecure_raw_read() instead, to allow those
- * functions to disable SIGPIPE and give better error messages on I/O errors.
- *
- * These functions are closely modelled on the standard socket BIO in OpenSSL;
- * see sock_read() and sock_write() in OpenSSL's crypto/bio/bss_sock.c.
- */
-
-#ifndef HAVE_BIO_GET_DATA
-#define BIO_get_data(bio) (bio->ptr)
-#define BIO_set_data(bio, data) (bio->ptr = data)
-#endif
-
 /* protected by ssl_config_mutex */
 static BIO_METHOD *my_bio_methods;
 
@@ -1828,7 +1814,7 @@ my_sock_read(BIO *h, char *buf, int size)
 {
 	int			res;
 
-	res = pqsecure_raw_read((PGconn *) BIO_get_data(h), buf, size);
+	res = pqsecure_raw_read((PGconn *) BIO_get_app_data(h), buf, size);
 	BIO_clear_retry_flags(h);
 	if (res < 0)
 	{
@@ -1858,7 +1844,7 @@ my_sock_write(BIO *h, const char *buf, int size)
 {
 	int			res;
 
-	res = pqsecure_raw_write((PGconn *) BIO_get_data(h), buf, size);
+	res = pqsecure_raw_write((PGconn *) BIO_get_app_data(h), buf, size);
 	BIO_clear_retry_flags(h);
 	if (res < 0)
 	{
@@ -1968,7 +1954,7 @@ my_SSL_set_fd(PGconn *conn, int fd)
 		SSLerr(SSL_F_SSL_SET_FD, ERR_R_BUF_LIB);
 		goto err;
 	}
-	BIO_set_data(bio, conn);
+	BIO_set_app_data(bio, conn);
 
 	SSL_set_bio(conn->ssl, bio, bio);
 	BIO_set_fd(bio, fd, BIO_NOCLOSE);
diff --git a/src/tools/msvc/Solution.pm b/src/tools/msvc/Solution.pm
index 98a5b5d872..a980b51f5d 100644
--- a/src/tools/msvc/Solution.pm
+++ b/src/tools/msvc/Solution.pm
@@ -224,7 +224,6 @@ sub GenerateFiles
 		HAVE_ATOMICS => 1,
 		HAVE_ATOMIC_H => undef,
 		HAVE_BACKTRACE_SYMBOLS => undef,
-		HAVE_BIO_GET_DATA => undef,
 		HAVE_BIO_METH_NEW => undef,
 		HAVE_COMPUTED_GOTO => undef,
 		HAVE_COPYFILE => undef,
@@ -502,7 +501,6 @@ sub GenerateFiles
 			|| ($digit1 >= '1' && $digit2 >= '1' && $digit3 >= '0'))
 		{
 			$define{HAVE_ASN1_STRING_GET0_DATA} = 1;
-			$define{HAVE_BIO_GET_DATA} = 1;
 			$define{HAVE_BIO_METH_NEW} = 1;
 			$define{HAVE_HMAC_CTX_FREE} = 1;
 			$define{HAVE_HMAC_CTX_NEW} = 1;
-- 
Tristan Partin
Neon (https://neon.tech)