URL: https://github.com/SSSD/sssd/pull/522
Author: abbra
Title: #522: Prepare SSSD to support IPA in trust to Samba AD
Action: synchronized
To pull the PR as Git branch:
git remote add ghsssd https://github.com/SSSD/sssd
git fetch ghsssd pull/522/head:pr522
git checkout pr522
From d40451f709c9104cacd8ca77864785d05d068485 Mon Sep 17 00:00:00 2001
From: Alexander Bokovoy <aboko...@redhat.com>
Date: Thu, 22 Feb 2018 14:38:51 +0200
Subject: [PATCH 1/2] ipa provider: expand search base to cover trusted domain
objects
In case of a two-way trust between FreeIPA and an Active Directory,
domain controller would use a TDO object in the trusting domain to
authenticate. Due to how trusted domain objects are used in Active
Directory, a domain controller from the trusted domain will synthesize
a Kerberos ticket for the TDO in the trusting domain. This ticket
will lack MS-PAC information because a trusted DC has no idea what
to put there. On IPA master smbd process will attempt to validate
successfully authenticated TDO principal by looking at its MS-PAC
structure, only to find it is missing. As result, smbd will revert
to a direct getpwnam().
Because TDO objects are stored under cn=trusts,$SUFFIX in FreeIPA,
they couldn't be found by SSSD which uses cn=accounts,$SUFFIX by
default. Add second search base to look up cn=trusts,$SUFFX to
allow TDO objects to be queried.
On FreeIPA side access controls are put in place so that only
AD trust agents are able to see a content of the cn=trusts,$SUFFIX
subtree.
Signed-of-by: Alexander Bokovoy <aboko...@redhat.com>
---
src/providers/ipa/ipa_common.c | 36 +++++++++++++++++++++++++++++++-----
1 file changed, 31 insertions(+), 5 deletions(-)
diff --git a/src/providers/ipa/ipa_common.c b/src/providers/ipa/ipa_common.c
index 2b81d7f3f..6599943da 100644
--- a/src/providers/ipa/ipa_common.c
+++ b/src/providers/ipa/ipa_common.c
@@ -176,9 +176,10 @@ int ipa_get_id_options(struct ipa_options *ipa_opts,
TALLOC_CTX *tmpctx;
char *basedn;
char *realm;
- char *value;
+ char *value, *user_base;
int ret;
int i;
+ bool server_mode;
tmpctx = talloc_new(ipa_opts);
if (!tmpctx) {
@@ -272,11 +273,36 @@ int ipa_get_id_options(struct ipa_options *ipa_opts,
ipa_opts->id->schema_type = SDAP_SCHEMA_IPA_V1;
/* set user/group search bases if they are not specified */
- if (NULL == dp_opt_get_string(ipa_opts->id->basic,
- SDAP_USER_SEARCH_BASE)) {
+ user_base = dp_opt_get_string(ipa_opts->id->basic, SDAP_USER_SEARCH_BASE);
+
+ /* In server mode we need to search both cn=accounts,$SUFFIX and
+ * cn=trusts,$SUFFIX to allow trusted domain object accounts to be found.
+ * Update user base if it wasn't set explicitly to multiple base DNs
+ */
+ server_mode = dp_opt_get_bool(ipa_opts->basic, IPA_SERVER_MODE);
+ if (server_mode != false) {
+ if ((NULL == user_base) || (NULL == strstr(user_base, "?cn=trusts,"))) {
+ /* Search both cn=accounts,$SUFFIX and cn=trusts,$SUFFIX. This allows
+ * to catch trusted domain objects used by trusted AD DCs to talk to
+ * Samba on IPA master */
+ value = talloc_asprintf(tmpctx,
+ "%s???cn=trusts,%s??(objectclass=ipaIDObject)",
+ user_base ? user_base :
+ dp_opt_get_string(ipa_opts->id->basic,
+ SDAP_SEARCH_BASE),
+ basedn);
+ }
+ } else {
+ value = dp_opt_get_string(ipa_opts->id->basic, SDAP_SEARCH_BASE);
+ }
+
+ if (NULL == user_base) {
+ if (!value) {
+ ret = ENOMEM;
+ goto done;
+ }
ret = dp_opt_set_string(ipa_opts->id->basic, SDAP_USER_SEARCH_BASE,
- dp_opt_get_string(ipa_opts->id->basic,
- SDAP_SEARCH_BASE));
+ value);
if (ret != EOK) {
goto done;
}
From 6b9403f373e19dabf2a1763e12fe139f51ac5dda Mon Sep 17 00:00:00 2001
From: Alexander Bokovoy <aboko...@redhat.com>
Date: Thu, 22 Feb 2018 14:45:16 +0200
Subject: [PATCH 2/2] ipa provider: always use a special keytab to talk to a
trusted DC
When FreeIPA is set up to trust an Active Directory forest, we should be
using trusted domain object credentials regardless of the trust
direction. Previously, SSSD relied on FreeIPA KDC issuing a cross-realm
referral towards a trusted domain. However, this does not work
currently with Samba AD and in general we want to move away to use
TDO in all cases as it is guaranteed to have correct permissions on AD
side.
Signed-of-by: Alexander Bokovoy <aboko...@redhat.com>
---
src/providers/ipa/ipa_subdomains_server.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/src/providers/ipa/ipa_subdomains_server.c b/src/providers/ipa/ipa_subdomains_server.c
index d670a156b..4c1ccf2bd 100644
--- a/src/providers/ipa/ipa_subdomains_server.c
+++ b/src/providers/ipa/ipa_subdomains_server.c
@@ -33,6 +33,7 @@
*/
#define LSA_TRUST_DIRECTION_INBOUND 0x00000001
#define LSA_TRUST_DIRECTION_OUTBOUND 0x00000002
+#define LSA_TRUST_DIRECTION_MASK (LSA_TRUST_DIRECTION_INBOUND | LSA_TRUST_DIRECTION_OUTBOUND)
static char *forest_keytab(TALLOC_CTX *mem_ctx, const char *forest)
{
@@ -663,11 +664,10 @@ ipa_server_trusted_dom_setup_send(TALLOC_CTX *mem_ctx,
subdom->name, state->forest,
ipa_trust_dir2str(state->direction));
- if (state->direction & LSA_TRUST_DIRECTION_OUTBOUND) {
- /* Use system keytab, nothing to do here */
- ret = EOK;
- goto immediate;
- } else if (state->direction & LSA_TRUST_DIRECTION_INBOUND) {
+ /* For both inbound and outbound trusts use a special keytab
+ * as this allows us to reuse the same logic in FreeIPA for
+ * both Microsoft AD and Samba AD */
+ if (state->direction & LSA_TRUST_DIRECTION_MASK) {
/* Need special keytab */
ret = ipa_server_trusted_dom_setup_1way(req);
if (ret == EAGAIN) {
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