50 lines
2.0 KiB
Diff
50 lines
2.0 KiB
Diff
From 297857dec4f82a802caa734670b57f0a18d942e2 Mon Sep 17 00:00:00 2001
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From: Greg Hudson <ghudson@mit.edu>
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Date: Sat, 11 Jul 2020 21:57:30 -0400
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Subject: [PATCH] Allow gss_unwrap_iov() of unpadded RC4 tokens
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Windows Remote Management, when used with an RC4 session key, appears
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to generate GSS wrap tokens with no padding instead of the expected
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one byte (RFC 4757 section 7.3). These tokens cannot be decoded with
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gss_unwrap() or a STREAM buffer (even with Microsoft SSPI), but SSPI
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allows them to be decoded using explicit IOVs with either a
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zero-length padding buffer or no padding buffer. Allow these cases to
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work in kg_fixup_padding_iov(). (It is already possible to make this
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work with HEADER | DATA | DATA, but only by
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accident--kg_fixup_padding_iov() doesn't find a data buffer because
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kg_locate_iov() only looks for singleton buffers, so it exits early.)
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ticket: 8926 (new)
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tags: pullup
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target_version: 1.18-next
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(cherry picked from commit 3f204ddd567715ef360b4bb0b32961b6a9877f9d)
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---
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src/lib/gssapi/krb5/util_crypt.c | 9 +++------
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1 file changed, 3 insertions(+), 6 deletions(-)
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diff --git a/src/lib/gssapi/krb5/util_crypt.c b/src/lib/gssapi/krb5/util_crypt.c
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index f7d3e92c4..d6c71aeb8 100644
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--- a/src/lib/gssapi/krb5/util_crypt.c
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+++ b/src/lib/gssapi/krb5/util_crypt.c
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@@ -638,16 +638,13 @@ kg_fixup_padding_iov(OM_uint32 *minor_status, gss_iov_buffer_desc *iov,
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data = kg_locate_iov(iov, iov_count, GSS_IOV_BUFFER_TYPE_DATA);
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padding = kg_locate_iov(iov, iov_count, GSS_IOV_BUFFER_TYPE_PADDING);
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- if (data == NULL) {
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+ /* Do nothing if padding is absent or empty, to allow unwrapping of WinRM
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+ * unpadded RC4 tokens using an explicit IOV array. */
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+ if (data == NULL || padding == NULL || padding->buffer.length == 0) {
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*minor_status = 0;
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return GSS_S_COMPLETE;
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}
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- if (padding == NULL || padding->buffer.length == 0) {
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- *minor_status = EINVAL;
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- return GSS_S_FAILURE;
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- }
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-
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p = (unsigned char *)padding->buffer.value;
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padlength = p[padding->buffer.length - 1];
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