* Thu Dec 19 2014 Roland Mainz <rmainz@redhat.com> - 1.13-4
- fix for CVE-2014-5354 (#1174546) "krb5: NULL pointer dereference when using keyless entries"
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Roland Mainz
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krb5-CVE_2014_5354_support_keyless_principals_in_LDAP.patch
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113
krb5-CVE_2014_5354_support_keyless_principals_in_LDAP.patch
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From 04038bf3633c4b909b5ded3072dc88c8c419bf16 Mon Sep 17 00:00:00 2001
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From: Ben Kaduk <kaduk@mit.edu>
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Date: Wed, 19 Nov 2014 12:04:46 -0500
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Subject: [PATCH] Support keyless principals in LDAP [CVE-2014-5354]
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Operations like "kadmin -q 'addprinc -nokey foo'" or
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"kadmin -q 'purgekeys -all foo'" result in principal entries with
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no keys present, so krb5_encode_krbsecretkey() would just return
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NULL, which then got unconditionally dereferenced in
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krb5_add_ber_mem_ldap_mod().
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Apply some fixes to krb5_encode_krbsecretkey() to handle zero-key
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principals better, correct the test for an allocation failure, and
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slightly restructure the cleanup handler to be shorter and more
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appropriate for the usage. Once it no longer short-circuits when
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n_key_data is zero, it will produce an array of length two with both
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entries NULL, which is treated as an empty list by the LDAP library,
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the correct behavior for a keyless principal.
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However, attributes with empty values are only handled by the LDAP
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library for Modify operations, not Add operations (which only get
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a sequence of Attribute, with no operation field). Therefore, only
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add an empty krbprincipalkey to the modlist when we will be performing a
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Modify, and not when we will be performing an Add, which is conditional
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on the (misspelled) create_standalone_prinicipal boolean.
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CVE-2014-5354:
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In MIT krb5, when kadmind is configured to use LDAP for the KDC
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database, an authenticated remote attacker can cause a NULL
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dereference by inserting into the database a principal entry which
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contains no long-term keys.
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In order for the LDAP KDC backend to translate a principal entry
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from the database abstraction layer into the form expected by the
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LDAP schema, the principal's keys are encoded into a
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NULL-terminated array of length-value entries to be stored in the
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LDAP database. However, the subroutine which produced this array
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did not correctly handle the case where no keys were present,
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returning NULL instead of an empty array, and the array was
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unconditionally dereferenced while adding to the list of LDAP
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operations to perform.
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Versions of MIT krb5 prior to 1.12 did not expose a way for
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principal entries to have no long-term key material, and
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therefore are not vulnerable.
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CVSSv2 Vector: AV:N/AC:M/Au:S/C:N/I:N/A:P/E:H/RL:OF/RC:C
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ticket: 8041 (new)
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tags: pullup
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target_version: 1.13.1
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subject: kadmind with ldap backend crashes when putting keyless entries
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---
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src/plugins/kdb/ldap/libkdb_ldap/ldap_principal2.c | 25 +++++++++++++++-------
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1 file changed, 17 insertions(+), 8 deletions(-)
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diff --git a/src/plugins/kdb/ldap/libkdb_ldap/ldap_principal2.c b/src/plugins/kdb/ldap/libkdb_ldap/ldap_principal2.c
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index 3e560d9..10b5982 100644
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--- a/src/plugins/kdb/ldap/libkdb_ldap/ldap_principal2.c
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+++ b/src/plugins/kdb/ldap/libkdb_ldap/ldap_principal2.c
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@@ -406,14 +406,14 @@ krb5_encode_krbsecretkey(krb5_key_data *key_data_in, int n_key_data,
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int num_versions = 1;
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int i, j, last;
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krb5_error_code err = 0;
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- krb5_key_data *key_data;
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+ krb5_key_data *key_data = NULL;
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- if (n_key_data <= 0)
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+ if (n_key_data < 0)
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return NULL;
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/* Make a shallow copy of the key data so we can alter it. */
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key_data = k5calloc(n_key_data, sizeof(*key_data), &err);
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- if (key_data_in == NULL)
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+ if (key_data == NULL)
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goto cleanup;
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memcpy(key_data, key_data_in, n_key_data * sizeof(*key_data));
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@@ -467,9 +467,8 @@ krb5_encode_krbsecretkey(krb5_key_data *key_data_in, int n_key_data,
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free(key_data);
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if (err != 0) {
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if (ret != NULL) {
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- for (i = 0; i <= num_versions; i++)
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- if (ret[i] != NULL)
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- free (ret[i]);
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+ for (i = 0; ret[i] != NULL; i++)
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+ free (ret[i]);
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free (ret);
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ret = NULL;
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}
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@@ -1036,9 +1035,19 @@ krb5_ldap_put_principal(krb5_context context, krb5_db_entry *entry,
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bersecretkey = krb5_encode_krbsecretkey (entry->key_data,
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entry->n_key_data, mkvno);
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- if ((st=krb5_add_ber_mem_ldap_mod(&mods, "krbprincipalkey",
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- LDAP_MOD_REPLACE | LDAP_MOD_BVALUES, bersecretkey)) != 0)
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+ if (bersecretkey == NULL) {
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+ st = ENOMEM;
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goto cleanup;
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+ }
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+ /* An empty list of bervals is only accepted for modify operations,
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+ * not add operations. */
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+ if (bersecretkey[0] != NULL || !create_standalone_prinicipal) {
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+ st = krb5_add_ber_mem_ldap_mod(&mods, "krbprincipalkey",
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+ LDAP_MOD_REPLACE | LDAP_MOD_BVALUES,
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+ bersecretkey);
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+ if (st != 0)
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+ goto cleanup;
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+ }
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if (!(entry->mask & KADM5_PRINCIPAL)) {
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memset(strval, 0, sizeof(strval));
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@ -43,7 +43,7 @@
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Summary: The Kerberos network authentication system
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Name: krb5
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Version: 1.13
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Release: 3%{?dist}
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Release: 4%{?dist}
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# - Maybe we should explode from the now-available-to-everybody tarball instead?
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# http://web.mit.edu/kerberos/dist/krb5/1.13/krb5-1.13-signed.tar
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# - The sources below are stored in a lookaside cache. Upload with
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@ -95,6 +95,7 @@ Patch129: krb5-1.11-run_user_0.patch
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Patch134: krb5-1.11-kpasswdtest.patch
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Patch136: krb5-socket_wrapper_eventfd_prototype_mismatch.patch
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Patch137: krb5-CVE_2014_5353_fix_LDAP_misused_policy_name_crash.patch
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Patch138: krb5-CVE_2014_5354_support_keyless_principals_in_LDAP.patch
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License: MIT
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URL: http://web.mit.edu/kerberos/www/
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@ -317,6 +318,7 @@ ln NOTICE LICENSE
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%endif
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%patch137 -p1
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%patch138 -p1
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# Take the execute bit off of documentation.
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chmod -x doc/krb5-protocol/*.txt doc/ccapi/*.html
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@ -988,6 +990,10 @@ exit 0
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%{_sbindir}/uuserver
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%changelog
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* Thu Dec 19 2014 Roland Mainz <rmainz@redhat.com> - 1.13-4
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- fix for CVE-2014-5354 (#1174546) "krb5: NULL pointer
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dereference when using keyless entries"
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* Wed Dec 17 2014 Roland Mainz <rmainz@redhat.com> - 1.13-3
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- fix for CVE-2014-5353 (#1174543) "Fix LDAP misused policy
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name crash"
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