56 lines
1.7 KiB
Diff
56 lines
1.7 KiB
Diff
From b6ab45da636118da83443516eee7d314f19b4e22 Mon Sep 17 00:00:00 2001
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From: Andrew Bartlett <abartlet@samba.org>
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Date: Mon, 4 Oct 2021 15:18:34 +1300
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Subject: [PATCH 235/266] CVE-2020-25722 kdc: Do not honour a request for a
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3-part SPN (ending in our domain/realm) unless a DC
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BUG: https://bugzilla.samba.org/show_bug.cgi?id=14776
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Signed-off-by: Andrew Bartlett <abartlet@samba.org>
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Reviewed-by: Joseph Sutton <josephsutton@catalyst.net.nz>
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Conflict:remove test
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Reference:https://gitlab.com/samba-team/samba/-/commit/b6ab45da636118da83443516eee7d314f19b4e22
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---
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source4/kdc/db-glue.c | 23 +++++++++++++++++++++++
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1 files changed, 23 insertions(+), 0 deletions(-)
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diff --git a/source4/kdc/db-glue.c b/source4/kdc/db-glue.c
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index d55bf1663d4..0f19e8d1c93 100644
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--- a/source4/kdc/db-glue.c
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+++ b/source4/kdc/db-glue.c
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@@ -968,6 +968,29 @@ static krb5_error_code samba_kdc_message2entry(krb5_context context,
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entry_ex->entry.flags.server = 0;
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}
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}
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+
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+ /*
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+ * We restrict a 3-part SPN ending in my domain/realm to full
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+ * domain controllers.
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+ *
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+ * This avoids any cases where (eg) a demoted DC still has
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+ * these more restricted SPNs.
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+ */
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+ if (krb5_princ_size(context, principal) > 2) {
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+ char *third_part
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+ = smb_krb5_principal_get_comp_string(mem_ctx,
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+ context,
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+ principal,
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+ 2);
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+ bool is_our_realm =
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+ lpcfg_is_my_domain_or_realm(lp_ctx,
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+ third_part);
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+ bool is_dc = userAccountControl &
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+ (UF_SERVER_TRUST_ACCOUNT | UF_PARTIAL_SECRETS_ACCOUNT);
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+ if (is_our_realm && !is_dc) {
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+ entry_ex->entry.flags.server = 0;
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+ }
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+ }
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/*
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* To give the correct type of error to the client, we must
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* not just return the entry without .server set, we must
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--
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2.23.0
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