59 lines
2.3 KiB
Diff
59 lines
2.3 KiB
Diff
From 51938a8b731740299fe47d132b8840edba4141bc Mon Sep 17 00:00:00 2001
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From: Robbie Harwood <rharwood@redhat.com>
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Date: Sat, 29 May 2021 12:05:49 -0400
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Subject: [PATCH] Fix k5tls module for OpenSSL 3
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Starting in OpenSSL 3, connection termination without a close_notify
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alert causes SSL_read() to return SSL_ERROR_SSL instead of
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SSL_ERROR_SYSCALL. OpenSSL 3 also provides a new option
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SSL_OP_IGNORE_UNEXPECTED_EOF which allows an application to explicitly
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ignore possible truncation attacks and receive SSL_ERROR_ZERO_RETURN
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instead.
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Remove the call to SSL_CTX_get_options() since SSL_CTX_set_options()
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doesn't clear existing options.
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[ghudson@mit.edu: edited commit message and comment]
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(cherry picked from commit aa9b4a2a64046afd2fab7cb49c346295874a5fb6)
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(cherry picked from commit 201e38845e9f70234bcaa9ba7c25b28e38169b0a)
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---
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src/plugins/tls/k5tls/openssl.c | 17 ++++++++++++++---
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1 file changed, 14 insertions(+), 3 deletions(-)
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diff --git a/src/plugins/tls/k5tls/openssl.c b/src/plugins/tls/k5tls/openssl.c
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index 76a43b3cd..99fda7ffc 100644
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--- a/src/plugins/tls/k5tls/openssl.c
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+++ b/src/plugins/tls/k5tls/openssl.c
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@@ -433,7 +433,7 @@ setup(krb5_context context, SOCKET fd, const char *servername,
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char **anchors, k5_tls_handle *handle_out)
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{
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int e;
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- long options;
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+ long options = SSL_OP_NO_SSLv2;
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SSL_CTX *ctx = NULL;
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SSL *ssl = NULL;
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k5_tls_handle handle = NULL;
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@@ -448,8 +448,19 @@ setup(krb5_context context, SOCKET fd, const char *servername,
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ctx = SSL_CTX_new(SSLv23_client_method());
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if (ctx == NULL)
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goto error;
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- options = SSL_CTX_get_options(ctx);
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- SSL_CTX_set_options(ctx, options | SSL_OP_NO_SSLv2);
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+
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+#ifdef SSL_OP_IGNORE_UNEXPECTED_EOF
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+ /*
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+ * For OpenSSL 3 and later, mark close_notify alerts as optional. We don't
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+ * need to worry about truncation attacks because the protocols this module
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+ * is used with (Kerberos and change-password) receive a single
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+ * length-delimited message from the server. For prior versions of OpenSSL
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+ * we check for SSL_ERROR_SYSCALL when reading instead (this error changes
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+ * to SSL_ERROR_SSL in OpenSSL 3).
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+ */
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+ options |= SSL_OP_IGNORE_UNEXPECTED_EOF;
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+#endif
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+ SSL_CTX_set_options(ctx, options);
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SSL_CTX_set_verify(ctx, SSL_VERIFY_PEER, verify_callback);
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X509_STORE_set_flags(SSL_CTX_get_cert_store(ctx), 0);
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