On Mon, 17 Aug 2015, Tomas Babej wrote:



On 08/17/2015 09:03 AM, Alexander Bokovoy wrote:
On Mon, 17 Aug 2015, Tomas Babej wrote:


On 08/13/2015 04:29 PM, Alexander Bokovoy wrote:
Hi,

see commit message for details.




Hi,

code-wise this looks good to me. Unfortunately, I have not been able to
verify in my setup that it fixes the issue in the linked BZ:

$ echo Secret123456 | ipa trust-add --type=ad ad.test --range-type
ipa-ad-trust --admin Administrator --password
------------------------------------------------
Added Active Directory trust for realm "ad.test"
------------------------------------------------
 Realm name: ad.test
 Domain NetBIOS name: AD
 Domain Security Identifier: S-1-5-21-1469936554-2294197481-461507924
 SID blacklist incoming: S-1-5-20, S-1-5-3, S-1-5-2, S-1-5-1, S-1-5-7,
S-1-5-6, S-1-5-5, S-1-5-4, S-1-5-9, S-1-5-8,
                         S-1-5-17, S-1-5-16, S-1-5-15, S-1-5-14,
S-1-5-13, S-1-5-12, S-1-5-11, S-1-5-10, S-1-3, S-1-2,
                         S-1-1, S-1-0, S-1-5-19, S-1-5-18
 SID blacklist outgoing: S-1-5-20, S-1-5-3, S-1-5-2, S-1-5-1, S-1-5-7,
S-1-5-6, S-1-5-5, S-1-5-4, S-1-5-9, S-1-5-8,
                         S-1-5-17, S-1-5-16, S-1-5-15, S-1-5-14,
S-1-5-13, S-1-5-12, S-1-5-11, S-1-5-10, S-1-3, S-1-2,
                         S-1-1, S-1-0, S-1-5-19, S-1-5-18
 Trust direction: Trusting forest
 Trust type: Active Directory domain
 Trust status: Established and verified

$ idrange-find

----------------
2 ranges matched
----------------
 Range name: AD.TEST_id_range
 First Posix ID of the range: 191200000
 Number of IDs in the range: 200000
 First RID of the corresponding RID range: 0
 Domain SID of the trusted domain:
S-1-5-21-1469936554-2294197481-461507924
 Range type: Active Directory domain range

 Range name: IPA.TEST_id_range
 First Posix ID of the range: 695200000
 Number of IDs in the range: 200000
 First RID of the corresponding RID range: 1000
 First RID of the secondary RID range: 100000000
 Range type: local domain range
----------------------------
Number of entries returned 2
----------------------------

However, I have one child subdomain in the setup:

$ ipa trustdomain-find
Realm name: ad.test
 Domain name: ad.test
 Domain NetBIOS name: AD
 Domain Security Identifier: S-1-5-21-1469936554-2294197481-461507924
 Domain enabled: True

 Domain name: sub.ad.test
 Domain NetBIOS name: SUB
 Domain Security Identifier: S-1-5-21-10134726-2575992721-4229914074
 Domain enabled: True
----------------------------
Number of entries returned 2
----------------------------
Look for AVCs, if there are any.

Also start abrtd and it should pick up any python exceptions in the
helper as 'crashes'.


Right. Insufficient LDAP permissions caused the following backtrace in
the oddjob helper:

ipaldap.py:948:error_handler:ACIError: Insufficient access: Insufficient
'add' privilege to add the entry
'cn=SUB.AD.TEST_id_range,cn=ranges,cn=etc,dc=ipa,dc=test'.

Traceback (most recent call last):
 File "/usr/libexec/ipa/com.redhat.idm.trust-fetch-domains", line 216,
in <module>
   trusted_domain, name, **dom)
 File "/usr/lib/python2.7/site-packages/ipalib/plugins/trust.py", line
347, in add_range
   ipanttrusteddomainsid=dom_sid)
 File "/usr/lib/python2.7/site-packages/ipalib/frontend.py", line 443,
in __call__
   ret = self.run(*args, **options)
 File "/usr/lib/python2.7/site-packages/ipalib/frontend.py", line 760,
in run
   return self.execute(*args, **options)
 File "/usr/lib/python2.7/site-packages/ipalib/plugins/baseldap.py",
line 1234, in execute
   self._exc_wrapper(keys, options, ldap.add_entry)(entry_attrs)
 File "/usr/lib/python2.7/site-packages/ipalib/plugins/baseldap.py",
line 1145, in wrapped
   return func(*call_args, **call_kwargs)
 File "/usr/lib/python2.7/site-packages/ipapython/ipaldap.py", line
1442, in add_entry
   self.conn.add_s(str(entry.dn), attrs.items())
 File "/usr/lib64/python2.7/contextlib.py", line 35, in __exit__
   self.gen.throw(type, value, traceback)
 File "/usr/lib/python2.7/site-packages/ipapython/ipaldap.py", line
948, in error_handler
   raise errors.ACIError(info=info)
ACIError: Insufficient access: Insufficient 'add' privilege to add the
entry 'cn=SUB.AD.TEST_id_range,cn=ranges,cn=etc,dc=ipa,dc=test'.

Local variables in innermost frame:
info: "Insufficient 'add' privilege to add the entry
'cn=SUB.AD.TEST_id_range,cn=ranges,cn=etc,dc=ipa,dc=test'."
arg_desc: None
self: ipaserver.plugins.ldap2.ldap2()
e: INSUFFICIENT_ACCESS({'info': "Insufficient 'add' privilege to add the
entry 'cn=SUB.AD.TEST_id_range,cn=ranges,cn=etc,dc=ipa,dc=test'.\n",
'desc': 'Insufficient access'},)
desc: 'Insufficient access'
Updated patch attached.

You can install freeipa from my COPR abbra/freeipa-oneway (you need
mkosek/freeipa-master COPR for dependencies) to test.
--
/ Alexander Bokovoy
From eb667407662906b609282b13f87129c80c058a9f Mon Sep 17 00:00:00 2001
From: Alexander Bokovoy <aboko...@redhat.com>
Date: Thu, 13 Aug 2015 17:18:57 +0300
Subject: [PATCH] trusts: harden trust-fetch-domains oddjobd-based script

When ipa-getkeytab is used to fetch trusted domain object credentials,
the fetched entry has always kvno 1. ipa-getkeytab always adds a key to
keytab which means older key versions will be in the SSSD keytab and
will confuse libkrb5 ccache initialization code as all kvno values are
equal to 1. Wrong key is picked up then and kinit fails.

To solve this problem, always remove existing
/var/lib/sss/keytabs/forest.keytab before retrieving a new one.

To make sure script's input cannot be used to define what should be
removed (by passing a relative path), make sure we retrieve trusted
forest name from LDAP. If it is not possible to retrieve, the script
will issue an exception and quit. If abrtd is running, this will be
recorded as a 'crash' and an attempt to use script by malicious user
would be recorded as well in the abrtd journal.

Additionally, as com.redhat.idm.trust-fetch-domains will create
ID ranges for the domains of the trusted forest if they don't exist,
it needs permissions to do so. The permission should be granted only
to cifs/ipa.master@IPA.REALM services which means they must have
krbprincipalname=cifs/*@IPA.REALM,cn=services,... DN and be members of
cn=adtrust agents,cn=sysaccounts,... group.

Solves https://bugzilla.redhat.com/show_bug.cgi?id=1250190

Ticket https://fedorahosted.org/freeipa/ticket/5182
---
 install/oddjob/com.redhat.idm.trust-fetch-domains | 29 +++++++++++++++++++----
 install/updates/20-aci.update                     |  4 ++++
 2 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/install/oddjob/com.redhat.idm.trust-fetch-domains 
b/install/oddjob/com.redhat.idm.trust-fetch-domains
index e50c81e..6a2171d 100755
--- a/install/oddjob/com.redhat.idm.trust-fetch-domains
+++ b/install/oddjob/com.redhat.idm.trust-fetch-domains
@@ -41,6 +41,9 @@ def retrieve_keytab(api, ccache_name, oneway_keytab_name, 
oneway_principal):
                       "-p", oneway_principal,
                       "-k", oneway_keytab_name,
                       "-r"]
+    if os.path.isfile(oneway_keytab_name):
+        os.unlink(oneway_keytab_name)
+
     (stdout, stderr, retcode) = ipautil.run(getkeytab_args,
                                             env={'KRB5CCNAME': ccache_name, 
'LANG': 'C'},
                                             raiseonerr=False)
@@ -111,7 +114,6 @@ from ipalib.plugins import trust
 # retrieve the keys to oneway_keytab_name.
 
 keytab_name = '/etc/samba/samba.keytab'
-oneway_keytab_name = '/var/lib/sss/keytabs/' + trusted_domain + '.keytab'
 
 principal = str('cifs/' + api.env.host)
 
@@ -137,10 +139,20 @@ else:
 old_ccache = os.environ.get('KRB5CCNAME')
 api.Backend.ldap2.connect(ccache)
 
+# Retrieve own NetBIOS name and trusted forest's name.
+# We use script's input to retrieve the trusted forest's name to sanitize input
+# for file-level access as we might need to wipe out keytab in 
/var/lib/sss/keytabs
 own_trust_dn = DN(('cn', api.env.domain),('cn','ad'), ('cn', 'etc'), 
api.env.basedn)
 own_trust_entry = api.Backend.ldap2.get_entry(own_trust_dn, ['ipantflatname'])
-own_trust_flatname = own_trust_entry['ipantflatname'][0].upper()
+own_trust_flatname = own_trust_entry.single_value.get('ipantflatname').upper()
+trusted_domain_dn = DN(('cn', trusted_domain.lower()), 
api.env.container_adtrusts, api.env.basedn)
+trusted_domain_entry = api.Backend.ldap2.get_entry(trusted_domain_dn, ['cn'])
+trusted_domain = trusted_domain_entry.single_value.get('cn').lower()
 
+# At this point if we didn't find trusted forest name, an exception will be 
raised
+# and script will quit. This is actually intended.
+
+oneway_keytab_name = '/var/lib/sss/keytabs/' + trusted_domain + '.keytab'
 oneway_principal = str('%s$@%s' % (own_trust_flatname, trusted_domain.upper()))
 
 # If keytab does not exist, retrieve it
@@ -152,11 +164,18 @@ try:
     # The keytab may have stale key material (from older trust-add run)
     if not os.path.isfile(oneway_ccache_name):
         oneway_ccache = kinit_keytab(oneway_principal, oneway_keytab_name, 
oneway_ccache_name)
+    else:
+        oneway_ccache_check = KRB5_CCache(oneway_ccache_name)
+        if not oneway_ccache_check.credential_is_valid(oneway_principal):
+            # If credentials were invalid, obtain them again
+            oneway_ccache = kinit_keytab(oneway_principal, oneway_keytab_name, 
oneway_ccache_name)
+        else:
+            oneway_ccache = oneway_ccache_check.ccache
 except krbV.Krb5Error as e:
     # If there was failure on using keytab, assume it is stale and retrieve 
again
     retrieve_keytab(api, ccache_name, oneway_keytab_name, oneway_principal)
 
-if oneway_ccache:
+try:
     # There wasn existing ccache, validate its content
     oneway_ccache_check = KRB5_CCache(oneway_ccache_name)
     if not oneway_ccache_check.credential_is_valid(oneway_principal):
@@ -164,7 +183,7 @@ if oneway_ccache:
         oneway_ccache = kinit_keytab(oneway_principal, oneway_keytab_name, 
oneway_ccache_name)
     else:
         oneway_ccache = oneway_ccache_check.ccache
-else:
+except krbV.Krb5Error as e:
     oneway_ccache = kinit_keytab(oneway_principal, oneway_keytab_name, 
oneway_ccache_name)
 
 # We are done: we have ccache with TDO credentials and can fetch domains
@@ -193,7 +212,7 @@ if domains:
                 dom['range_type'] = u'ipa-ad-trust'
                 # Do not pass ipaserver.dcerpc.TrustInstance to trust.add_range
                 # to force it using existing credentials cache
-                trust.add_range(None, range_name, dom['ipanttrusteddomainsid'],
+                trust.add_range(api, None, range_name, 
dom['ipanttrusteddomainsid'],
                                 trusted_domain, name, **dom)
         except errors.DuplicateEntry:
             # Ignore updating duplicate entries
diff --git a/install/updates/20-aci.update b/install/updates/20-aci.update
index 0bdeeb6..cba1897 100644
--- a/install/updates/20-aci.update
+++ b/install/updates/20-aci.update
@@ -87,3 +87,7 @@ add:aci:(targetattr = "usercertificate")(version 3.0;acl 
"selfservice:Users can
 # Hosts can add their own services
 dn: cn=services,cn=accounts,$SUFFIX
 add:aci: (target = 
"ldap:///krbprincipalname=*/($$dn)@$REALM,cn=services,cn=accounts,$SUFFIX")(targetfilter
 = "(objectClass=ipaKrbPrincipal)")(version 3.0;acl "Hosts can add own 
services"; allow(add) 
userdn="ldap:///fqdn=($$dn),cn=computers,cn=accounts,$SUFFIX";)
+
+# CIFS service on the master can manage ID ranges
+dn: cn=ranges,cn=etc,$SUFFIX
+add:aci: (target = "ldap:///cn=*,cn=ranges,cn=etc,$SUFFIX";)(targetfilter = 
"(objectClass=ipaIDrange)")(version 3.0;acl "CIFS service can manage ID ranges 
for trust"; allow(all) 
userdn="ldap:///krbprincipalname=cifs/*@$REALM,cn=services,cn=accounts,$SUFFIX"; 
and groupdn="ldap:///cn=adtrust agents,cn=sysaccounts,cn=etc,$SUFFIX";)
-- 
2.4.3

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