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Fix lookup_unix_user_name to support realm-qualified lookups 

Fixes lookups from Windows clients when using Global Catalog searches.
Required for upcoming FreeIPA Global Catalog support.
This commit is contained in:
Alexander Bokovoy 2020-10-22 10:12:06 +03:00
parent a172510646
commit 1e29c417eb
2 changed files with 213 additions and 0 deletions
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210
samba-gc-lookup_unix_user_name-allow-lookup-for-own-realm.patch Normal file
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@ -0,0 +1,210 @@
From 81d6949acdad70ecfb130d3286eeab1b3a51937f Mon Sep 17 00:00:00 2001
From: Alexander Bokovoy <ab@samba.org>
Date: Wed, 7 Oct 2020 19:25:24 +0300
Subject: [PATCH 1/2] cli_credentials_parse_string: fix parsing of principals
When parsing a principal-like name, user name was left with full
principal instead of taking only the left part before '@' sign.
>>> from samba import credentials
>>> t = credentials.Credentials()
>>> t.parse_string('admin@realm.test', credentials.SPECIFIED)
>>> t.get_username()
'admin@realm.test'
The issue is that cli_credentials_set_username() does a talloc_strdup()
of the argument, so we need to change order of assignment to allow
talloc_strdup() to copy the right part of the string.
Signed-off-by: Alexander Bokovoy <ab@samba.org>
---
auth/credentials/credentials.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/auth/credentials/credentials.c b/auth/credentials/credentials.c
index 77c35dd104b..06ac79058f9 100644
--- a/auth/credentials/credentials.c
+++ b/auth/credentials/credentials.c
@@ -840,11 +840,10 @@ _PUBLIC_ void cli_credentials_parse_string(struct cli_credentials *credentials,
* in order to undo the effect of
* cli_credentials_guess().
*/
- cli_credentials_set_username(credentials, uname, obtained);
- cli_credentials_set_domain(credentials, "", obtained);
-
cli_credentials_set_principal(credentials, uname, obtained);
*p = 0;
+ cli_credentials_set_username(credentials, uname, obtained);
+ cli_credentials_set_domain(credentials, "", obtained);
cli_credentials_set_realm(credentials, p+1, obtained);
return;
} else if ((p = strchr_m(uname,'\\'))
--
2.28.0
From fa38bebb993011428612d51819530218d8358f5e Mon Sep 17 00:00:00 2001
From: Alexander Bokovoy <ab@samba.org>
Date: Mon, 13 Jan 2020 16:04:20 +0200
Subject: [PATCH 2/2] lookup_name: allow lookup for own realm
When using security tab in Windows Explorer, a lookup over a trusted
forest might come as realm\name instead of NetBIOS domain name:
--------------------------------------------------------------------
[2020/01/13 11:12:39.859134, 1, pid=33253, effective(1732401004, 1732401004), real(1732401004, 0), class=rpc_parse] ../../librpc/ndr/ndr.c:471(ndr_print_function_debug)
lsa_LookupNames3: struct lsa_LookupNames3
in: struct lsa_LookupNames3
handle : *
handle: struct policy_handle
handle_type : 0x00000000 (0)
uuid : 0000000e-0000-0000-1c5e-a750e5810000
num_names : 0x00000001 (1)
names: ARRAY(1)
names: struct lsa_String
length : 0x001e (30)
size : 0x0020 (32)
string : *
string : 'ipa.test\admins'
sids : *
sids: struct lsa_TransSidArray3
count : 0x00000000 (0)
sids : NULL
level : LSA_LOOKUP_NAMES_UPLEVEL_TRUSTS_ONLY2 (6)
count : *
count : 0x00000000 (0)
lookup_options : LSA_LOOKUP_OPTION_SEARCH_ISOLATED_NAMES (0)
client_revision : LSA_CLIENT_REVISION_2 (2)
--------------------------------------------------------------------
Allow this lookup using realm to be done against primary domain.
Refactor user name parsing code to reuse cli_credentials_* API to be
consistent with other places. cli_credentials_parse_string() handles
both domain and realm-based user name variants.
Signed-off-by: Alexander Bokovoy <ab@samba.org>
---
source3/passdb/lookup_sid.c | 75 ++++++++++++++++++++++++++-----------
1 file changed, 53 insertions(+), 22 deletions(-)
diff --git a/source3/passdb/lookup_sid.c b/source3/passdb/lookup_sid.c
index 82c47b3145b..39d599fed27 100644
--- a/source3/passdb/lookup_sid.c
+++ b/source3/passdb/lookup_sid.c
@@ -29,6 +29,7 @@
#include "../libcli/security/security.h"
#include "lib/winbind_util.h"
#include "../librpc/gen_ndr/idmap.h"
+#include "auth/credentials/credentials.h"
static bool lookup_unix_user_name(const char *name, struct dom_sid *sid)
{
@@ -78,52 +79,82 @@ bool lookup_name(TALLOC_CTX *mem_ctx,
const char **ret_domain, const char **ret_name,
struct dom_sid *ret_sid, enum lsa_SidType *ret_type)
{
- char *p;
const char *tmp;
const char *domain = NULL;
const char *name = NULL;
+ const char *realm = NULL;
uint32_t rid;
struct dom_sid sid;
enum lsa_SidType type;
TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
+ struct cli_credentials *creds = NULL;
if (tmp_ctx == NULL) {
DEBUG(0, ("talloc_new failed\n"));
return false;
}
- p = strchr_m(full_name, '\\');
-
- if (p != NULL) {
- domain = talloc_strndup(tmp_ctx, full_name,
- PTR_DIFF(p, full_name));
- name = talloc_strdup(tmp_ctx, p+1);
- } else {
- domain = talloc_strdup(tmp_ctx, "");
- name = talloc_strdup(tmp_ctx, full_name);
+ creds = cli_credentials_init(tmp_ctx);
+ if (creds == NULL) {
+ DEBUG(0, ("cli_credentials_init failed\n"));
+ return false;
}
- if ((domain == NULL) || (name == NULL)) {
- DEBUG(0, ("talloc failed\n"));
- TALLOC_FREE(tmp_ctx);
+ cli_credentials_parse_string(creds, full_name, CRED_SPECIFIED);
+ name = cli_credentials_get_username(creds);
+ domain = cli_credentials_get_domain(creds);
+ realm = cli_credentials_get_realm(creds);
+
+ /* At this point we have:
+ * - name -- normal name or empty string
+ * - domain -- either NULL or domain name
+ * - realm -- either NULL or realm name
+ *
+ * domain and realm are exclusive to each other
+ * the code below in lookup_name assumes domain
+ * to be at least empty string, not NULL
+ */
+
+ if ((name == NULL) || (name[0] == '\0')) {
+ DEBUG(0, ("lookup_name with empty name, exit\n"));
return false;
}
+ if ((domain == NULL) && (realm == NULL)) {
+ domain = talloc_strdup(creds, "");
+ }
+
DEBUG(10,("lookup_name: %s => domain=[%s], name=[%s]\n",
full_name, domain, name));
DEBUG(10, ("lookup_name: flags = 0x0%x\n", flags));
- if (((flags & LOOKUP_NAME_DOMAIN) || (flags == 0)) &&
- strequal(domain, get_global_sam_name()))
- {
+ /* Windows clients may send a LookupNames request with both NetBIOS
+ * domain name- and realm-qualified user names. Thus, we need to check
+ * both against both of the SAM domain name and realm, if set. Since
+ * domain name and realm in the request are exclusive, test the one
+ * that is specified. cli_credentials_parse_string() will either set
+ * realm or wouldn't so we can use it to detect if realm was specified.
+ */
+ if ((flags & LOOKUP_NAME_DOMAIN) || (flags == 0)) {
+ const char *domain_name = realm ? realm : domain;
+ bool check_global_sam = false;
+
+ if (domain_name[0] != '\0') {
+ check_global_sam = strequal(domain_name, get_global_sam_name());
+ if (!check_global_sam && lp_realm() != NULL) {
+ check_global_sam = strequal(domain_name, lp_realm());
+ }
+ }
- /* It's our own domain, lookup the name in passdb */
- if (lookup_global_sam_name(name, flags, &rid, &type)) {
- sid_compose(&sid, get_global_sam_sid(), rid);
- goto ok;
+ if (check_global_sam) {
+ /* It's our own domain, lookup the name in passdb */
+ if (lookup_global_sam_name(name, flags, &rid, &type)) {
+ sid_compose(&sid, get_global_sam_sid(), rid);
+ goto ok;
+ }
+ TALLOC_FREE(tmp_ctx);
+ return false;
}
- TALLOC_FREE(tmp_ctx);
- return false;
}
if ((flags & LOOKUP_NAME_BUILTIN) &&
--
2.28.0

3
samba.spec
View File

@ -131,6 +131,7 @@ Source14: samba.pamd
Source201: README.downgrade
Patch1: samba-s4u.patch
Patch2: samba-gc-lookup_unix_user_name-allow-lookup-for-own-realm.patch
Requires(pre): /usr/sbin/groupadd
Requires(post): systemd
@ -3623,6 +3624,8 @@ fi
* Thu Oct 22 2020 Alexander Bokovoy <abokovoy@redhat.com> - 4.13.0-12
- Add preliminary support for S4U operations in Samba AD DC
resolves: #1836630 - Samba DC: Remote Desktop cannot access files
- Fix lookup_unix_user_name to allow lookup of realm-qualified users and groups
required for upcoming FreeIPA Global Catalog support
* Tue Sep 22 2020 Guenther Deschner <gdeschner@redhat.com> - 4.13.0-11
- Update to Samba 4.13.0