92 lines
4.0 KiB
Diff
92 lines
4.0 KiB
Diff
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From 651b9b8084ecff5553b7ef6ee723ce7c4438a9d8 Mon Sep 17 00:00:00 2001
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From: Alexander Scheel <ascheel@redhat.com>
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Date: Wed, 5 Jul 2017 11:38:30 -0400
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Subject: [PATCH] Implement GSS_C_CHANNEL_BOUND_FLAG
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Define a new channel-bound GSS return flag, and set it in the krb5
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mech if the initiator sent channel bindings matching the acceptor's.
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Do not error out if the acceptor specifies channel bindings and the
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initiator does not send them.
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[ghudson@mit.edu: simplified code changes; fleshed out commit message]
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[iboukris: cherry-picked from another PR and reduced in scope]
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ticket: 8899 (new)
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(cherry picked from commit 429a31146083fac21958631c2af572b08ec91022)
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---
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src/lib/gssapi/generic/gssapi_ext.h | 2 ++
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src/lib/gssapi/krb5/accept_sec_context.c | 18 +++++++++++++-----
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2 files changed, 15 insertions(+), 5 deletions(-)
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diff --git a/src/lib/gssapi/generic/gssapi_ext.h b/src/lib/gssapi/generic/gssapi_ext.h
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index 218456e44..c675e8ebb 100644
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--- a/src/lib/gssapi/generic/gssapi_ext.h
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+++ b/src/lib/gssapi/generic/gssapi_ext.h
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@@ -595,6 +595,8 @@ gss_store_cred_into(
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* attribute (along with any applicable RFC 5587 attributes).
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*/
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+#define GSS_C_CHANNEL_BOUND_FLAG 2048 /* 0x00000800 */
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+
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OM_uint32 KRB5_CALLCONV
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gssspi_query_meta_data(
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OM_uint32 *minor_status,
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diff --git a/src/lib/gssapi/krb5/accept_sec_context.c b/src/lib/gssapi/krb5/accept_sec_context.c
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index 70dd7fc0c..9d3e2f4fe 100644
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--- a/src/lib/gssapi/krb5/accept_sec_context.c
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+++ b/src/lib/gssapi/krb5/accept_sec_context.c
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@@ -427,6 +427,9 @@ kg_process_extension(krb5_context context,
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GSS_C_SEQUENCE_FLAG | GSS_C_DCE_STYLE | \
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GSS_C_IDENTIFY_FLAG | GSS_C_EXTENDED_ERROR_FLAG)
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+/* A zero-value channel binding, for comparison */
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+static const uint8_t null_cb[CB_MD5_LEN];
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+
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/*
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* The krb5 GSS mech appropriates the authenticator checksum field from RFC
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* 4120 to store structured data instead of a checksum, indicated with checksum
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@@ -435,9 +438,10 @@ kg_process_extension(krb5_context context,
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*
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* Interpret the checksum. Read delegated creds into *deleg_out if it is not
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* NULL. Set *flags_out to the allowed subset of token flags, plus
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- * GSS_C_DELEG_FLAG if a delegated credential was present. Process any
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- * extensions found using exts. On error, set *code_out to a krb5_error code
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- * for use as a minor status value.
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+ * GSS_C_DELEG_FLAG if a delegated credential was present and
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+ * GSS_C_CHANNEL_BOUND_FLAG if matching channel bindings are present. Process
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+ * any extensions found using exts. On error, set *code_out to a krb5_error
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+ * code for use as a minor status value.
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*/
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static OM_uint32
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process_checksum(OM_uint32 *minor_status, krb5_context context,
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@@ -450,7 +454,7 @@ process_checksum(OM_uint32 *minor_status, krb5_context context,
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krb5_error_code code = 0;
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OM_uint32 status, option_id, token_flags;
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size_t cb_len, option_len;
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- krb5_boolean valid;
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+ krb5_boolean valid, token_cb_present = FALSE, cb_match = FALSE;
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krb5_key subkey;
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krb5_data option, empty = empty_data();
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krb5_checksum cb_cksum;
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@@ -516,7 +520,9 @@ process_checksum(OM_uint32 *minor_status, krb5_context context,
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goto fail;
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}
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assert(cb_cksum.length == cb_len);
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- if (k5_bcmp(token_cb, cb_cksum.contents, cb_len) != 0) {
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+ token_cb_present = (k5_bcmp(token_cb, null_cb, cb_len) != 0);
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+ cb_match = (k5_bcmp(token_cb, cb_cksum.contents, cb_len) == 0);
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+ if (token_cb_present && !cb_match) {
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status = GSS_S_BAD_BINDINGS;
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goto fail;
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}
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@@ -525,6 +531,8 @@ process_checksum(OM_uint32 *minor_status, krb5_context context,
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/* Read the token flags and accept some of them as context flags. */
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token_flags = k5_input_get_uint32_le(&in);
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*flags_out = token_flags & INITIATOR_FLAGS;
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+ if (cb_match)
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+ *flags_out |= GSS_C_CHANNEL_BOUND_FLAG;
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/* Read the delegated credential if present. */
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if (in.len >= 4 && (token_flags & GSS_C_DELEG_FLAG)) {
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