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unnilennium |
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From 2a9e5a9a226a4628546dbaaea59ff78fe32a2352 Mon Sep 17 00:00:00 2001 |
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From: Stefan Metzmacher <metze@samba.org> |
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Date: Thu, 1 Sep 2016 08:08:23 +0200 |
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Subject: [PATCH] gensec/spnego: work around missing server mechListMIC in SMB |
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servers |
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BUG: https://bugzilla.samba.org/show_bug.cgi?id=11994 |
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Signed-off-by: Stefan Metzmacher <metze@samba.org> |
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Reviewed-by: Christian Ambach <ambi@samba.org> |
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Autobuild-User(master): Christian Ambach <ambi@samba.org> |
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Autobuild-Date(master): Fri Sep 2 18:10:44 CEST 2016 on sn-devel-144 |
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(cherry picked from commit 9b45ba5cd53bd513eb777590815a0b8408af64e2) |
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--- |
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auth/gensec/spnego.c | 69 +++++++++++++++++++++++++++++++++++++++++++++++++++- |
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1 file changed, 68 insertions(+), 1 deletion(-) |
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diff --git a/auth/gensec/spnego.c b/auth/gensec/spnego.c |
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index ef30ab7..5f5047a 100644 |
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--- a/auth/gensec/spnego.c |
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+++ b/auth/gensec/spnego.c |
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@@ -55,9 +55,11 @@ struct spnego_state { |
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DATA_BLOB mech_types; |
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size_t num_targs; |
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+ bool downgraded; |
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bool mic_requested; |
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bool needs_mic_sign; |
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bool needs_mic_check; |
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+ bool may_skip_mic_check; |
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bool done_mic_check; |
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bool simulate_w2k; |
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@@ -434,6 +436,7 @@ static NTSTATUS gensec_spnego_parse_negTokenInit(struct gensec_security *gensec_ |
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* Indicate the downgrade and request a |
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* mic. |
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*/ |
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+ spnego_state->downgraded = true; |
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spnego_state->mic_requested = true; |
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break; |
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} |
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@@ -1078,7 +1081,7 @@ static NTSTATUS gensec_spnego_update(struct gensec_security *gensec_security, TA |
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DEBUG(3,("GENSEC SPNEGO: client preferred mech (%s) not accepted, server wants: %s\n", |
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gensec_get_name_by_oid(gensec_security, spnego_state->neg_oid), |
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gensec_get_name_by_oid(gensec_security, spnego.negTokenTarg.supportedMech))); |
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- |
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+ spnego_state->downgraded = true; |
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spnego_state->no_response_expected = false; |
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talloc_free(spnego_state->sub_sec_security); |
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nt_status = gensec_subcontext_start(spnego_state, |
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@@ -1135,6 +1138,23 @@ static NTSTATUS gensec_spnego_update(struct gensec_security *gensec_security, TA |
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return NT_STATUS_INVALID_PARAMETER; |
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} |
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+ if (spnego.negTokenTarg.mechListMIC.length == 0 |
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+ && spnego_state->may_skip_mic_check) { |
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+ /* |
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+ * In this case we don't require |
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+ * a mechListMIC from the server. |
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+ * |
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+ * This works around bugs in the Azure |
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+ * and Apple spnego implementations. |
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+ * |
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+ * See |
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+ * https://bugzilla.samba.org/show_bug.cgi?id=11994 |
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+ */ |
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+ spnego_state->needs_mic_check = false; |
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+ nt_status = NT_STATUS_OK; |
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+ goto client_response; |
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+ } |
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+ |
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nt_status = gensec_check_packet(spnego_state->sub_sec_security, |
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spnego_state->mech_types.data, |
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spnego_state->mech_types.length, |
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@@ -1190,9 +1210,56 @@ static NTSTATUS gensec_spnego_update(struct gensec_security *gensec_security, TA |
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*/ |
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new_spnego = false; |
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} |
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+ |
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break; |
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case SPNEGO_ACCEPT_INCOMPLETE: |
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+ if (spnego.negTokenTarg.mechListMIC.length > 0) { |
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+ new_spnego = true; |
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+ break; |
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+ } |
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+ |
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+ if (spnego_state->downgraded) { |
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+ /* |
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+ * A downgrade should be protected if |
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+ * supported |
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+ */ |
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+ break; |
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+ } |
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+ |
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+ /* |
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+ * The caller may just asked for |
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+ * GENSEC_FEATURE_SESSION_KEY, this |
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+ * is only reflected in the want_features. |
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+ * |
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+ * As it will imply |
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+ * gensec_have_features(GENSEC_FEATURE_SIGN) |
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+ * to return true. |
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+ */ |
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+ if (gensec_security->want_features & GENSEC_FEATURE_SIGN) { |
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+ break; |
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+ } |
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+ if (gensec_security->want_features & GENSEC_FEATURE_SEAL) { |
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+ break; |
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+ } |
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+ /* |
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+ * Here we're sure our preferred mech was |
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+ * selected by the server and our caller doesn't |
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+ * need GENSEC_FEATURE_SIGN nor |
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+ * GENSEC_FEATURE_SEAL support. |
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+ * |
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+ * In this case we don't require |
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+ * a mechListMIC from the server. |
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+ * |
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+ * This works around bugs in the Azure |
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+ * and Apple spnego implementations. |
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+ * |
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+ * See |
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+ * https://bugzilla.samba.org/show_bug.cgi?id=11994 |
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+ */ |
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+ spnego_state->may_skip_mic_check = true; |
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+ break; |
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+ |
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case SPNEGO_REQUEST_MIC: |
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if (spnego.negTokenTarg.mechListMIC.length > 0) { |
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new_spnego = true; |
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-- |
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2.8.0.rc3.226.g39d4020 |
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