Matěj Cepl
04e45231c3
(from gh#python/cpython!100373/files) Stopping SSLContext.load_verify_locations from accepting some cases of trailing data in DER.
75 lines
3.2 KiB
Diff
75 lines
3.2 KiB
Diff
From 863a0a7badf3919c4a710df67e98dbf5db0a2690 Mon Sep 17 00:00:00 2001
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From: David Benjamin <davidben@google.com>
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Date: Tue, 20 Dec 2022 10:36:19 -0500
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Subject: [PATCH] gh-100372: Use BIO_eof to detect EOF for SSL_FILETYPE_ASN1
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In PEM, we need to parse until error and then suppress
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PEM_R_NO_START_LINE, because PEM allows arbitrary leading and trailing
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data. DER, however, does not. Parsing until error and suppressing
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ASN1_R_HEADER_TOO_LONG doesn't quite work because that error also
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covers some cases that should be rejected.
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Instead, check BIO_eof early and stop the loop that way.
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---
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Lib/test/test_ssl.py | 2 ++
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Misc/NEWS.d/next/Library/2022-12-20-10-55-14.gh-issue-100372.utfP65.rst | 2 ++
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Modules/_ssl.c | 10 ++++++----
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3 files changed, 10 insertions(+), 4 deletions(-)
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create mode 100644 Misc/NEWS.d/next/Library/2022-12-20-10-55-14.gh-issue-100372.utfP65.rst
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Index: Python-3.6.15/Lib/test/test_ssl.py
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===================================================================
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--- Python-3.6.15.orig/Lib/test/test_ssl.py
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+++ Python-3.6.15/Lib/test/test_ssl.py
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@@ -1209,6 +1209,8 @@ class ContextTests(unittest.TestCase):
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"not enough data: cadata does not contain a certificate"
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):
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ctx.load_verify_locations(cadata=b"broken")
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+ with self.assertRaises(ssl.SSLError):
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+ ctx.load_verify_locations(cadata=cacert_der + b"A")
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def test_load_dh_params(self):
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Index: Python-3.6.15/Misc/NEWS.d/next/Library/2022-12-20-10-55-14.gh-issue-100372.utfP65.rst
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===================================================================
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--- /dev/null
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+++ Python-3.6.15/Misc/NEWS.d/next/Library/2022-12-20-10-55-14.gh-issue-100372.utfP65.rst
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@@ -0,0 +1,2 @@
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+:meth:`ssl.SSLContext.load_verify_locations` no longer incorrectly accepts
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+some cases of trailing data when parsing DER.
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Index: Python-3.6.15/Modules/_ssl.c
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===================================================================
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--- Python-3.6.15.orig/Modules/_ssl.c
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+++ Python-3.6.15/Modules/_ssl.c
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@@ -3579,7 +3579,7 @@ _add_ca_certs(PySSLContext *self, void *
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{
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BIO *biobuf = NULL;
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X509_STORE *store;
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- int retval = -1, err, loaded = 0;
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+ int retval = -1, err, loaded = 0, was_bio_eof = 0;
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assert(filetype == SSL_FILETYPE_ASN1 || filetype == SSL_FILETYPE_PEM);
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@@ -3607,6 +3607,10 @@ _add_ca_certs(PySSLContext *self, void *
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int r;
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if (filetype == SSL_FILETYPE_ASN1) {
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+ if (BIO_eof(biobuf)) {
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+ was_bio_eof = 1;
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+ break;
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+ }
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cert = d2i_X509_bio(biobuf, NULL);
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} else {
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cert = PEM_read_bio_X509(biobuf, NULL,
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@@ -3642,9 +3646,7 @@ _add_ca_certs(PySSLContext *self, void *
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}
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_setSSLError(msg, 0, __FILE__, __LINE__);
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retval = -1;
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- } else if ((filetype == SSL_FILETYPE_ASN1) &&
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- (ERR_GET_LIB(err) == ERR_LIB_ASN1) &&
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- (ERR_GET_REASON(err) == ASN1_R_HEADER_TOO_LONG)) {
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+ } else if ((filetype == SSL_FILETYPE_ASN1) && was_bio_eof) {
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/* EOF ASN1 file, not an error */
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ERR_clear_error();
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retval = 0;
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