1 files changed, 131 insertions, 47 deletions

diff --git a/src/openvpnserv/validate.c b/src/openvpnserv/validate.c
index c9c3855..f6a97e9 100644
--- a/src/openvpnserv/validate.c
+++ b/src/openvpnserv/validate.c
@@ -16,10 +16,9 @@
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  *  GNU General Public License for more details.
  *
- *  You should have received a copy of the GNU General Public License
- *  along with this program (see the file COPYING included with this
- *  distribution); if not, write to the Free Software Foundation, Inc.,
- *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
 #include "validate.h"
@@ -49,6 +48,9 @@ static const WCHAR *white_list[] =
     NULL                                /* last value */
 };
 
+static BOOL IsUserInGroup(PSID sid, const PTOKEN_GROUPS groups, const WCHAR *group_name);
+static PTOKEN_GROUPS GetTokenGroups(const HANDLE token);
+
 /*
  * Check workdir\fname is inside config_dir
  * The logic here is simple: we may reject some valid paths if ..\ is in any of the strings
@@ -147,21 +149,16 @@ GetBuiltinAdminGroupName(WCHAR *name, DWORD nlen)
 
 /*
  * Check whether user is a member of Administrators group or
- * the group specified in s->ovpn_admin_group
+ * the group specified in ovpn_admin_group
  */
 BOOL
-IsAuthorizedUser(SID *sid, settings_t *s)
+IsAuthorizedUser(PSID sid, const HANDLE token, const WCHAR *ovpn_admin_group)
 {
-    LOCALGROUP_USERS_INFO_0 *groups = NULL;
-    DWORD nread;
-    DWORD nmax;
-    WCHAR *tmp = NULL;
     const WCHAR *admin_group[2];
     WCHAR username[MAX_NAME];
     WCHAR domain[MAX_NAME];
     WCHAR sysadmin_group[MAX_NAME];
-    DWORD err, len = MAX_NAME;
-    int i;
+    DWORD len = MAX_NAME;
     BOOL ret = FALSE;
     SID_NAME_USE sid_type;
 
@@ -169,17 +166,9 @@ IsAuthorizedUser(SID *sid, settings_t *s)
     if (!LookupAccountSidW(NULL, sid, username, &len, domain, &len, &sid_type))
     {
         MsgToEventLog(M_SYSERR, TEXT("LookupAccountSid"));
-        goto out;
-    }
-
-    /* Get an array of groups the user is member of */
-    err = NetUserGetLocalGroups(NULL, username, 0, LG_INCLUDE_INDIRECT, (LPBYTE *) &groups,
-                                MAX_PREFERRED_LENGTH, &nread, &nmax);
-    if (err && err != ERROR_MORE_DATA)
-    {
-        SetLastError(err);
-        MsgToEventLog(M_SYSERR, TEXT("NetUserGetLocalGroups"));
-        goto out;
+        /* not fatal as this is now used only for logging */
+        username[0] = '\0';
+        domain[0] = '\0';
     }
 
     if (GetBuiltinAdminGroupName(sysadmin_group, _countof(sysadmin_group)))
@@ -192,41 +181,136 @@ IsAuthorizedUser(SID *sid, settings_t *s)
         /* use the default value */
         admin_group[0] = SYSTEM_ADMIN_GROUP;
     }
+    admin_group[1] = ovpn_admin_group;
 
-#ifdef UNICODE
-    admin_group[1] = s->ovpn_admin_group;
-#else
-    tmp = NULL;
-    len = MultiByteToWideChar(CP_UTF8, 0, s->ovpn_admin_group, -1, NULL, 0);
-    if (len == 0 || (tmp = malloc(len*sizeof(WCHAR))) == NULL)
+    PTOKEN_GROUPS token_groups = GetTokenGroups(token);
+    for (int i = 0; i < 2; ++i)
     {
-        MsgToEventLog(M_SYSERR, TEXT("Failed to convert admin group name to WideChar"));
-        goto out;
+        ret = IsUserInGroup(sid, token_groups, admin_group[i]);
+        if (ret)
+        {
+            MsgToEventLog(M_INFO, TEXT("Authorizing user '%s@%s' by virtue of membership in group '%s'"),
+                          username, domain, admin_group[i]);
+            goto out;
+        }
     }
-    MultiByteToWideChar(CP_UTF8, 0, s->ovpn_admin_group, -1, tmp, len);
-    admin_group[1] = tmp;
-#endif
 
-    /* Check if user's groups include any of the admin groups */
-    for (i = 0; i < nread; i++)
+out:
+    free(token_groups);
+    return ret;
+}
+
+/**
+ * Get a list of groups in token.
+ * Returns a pointer to TOKEN_GROUPS struct or NULL on error.
+ * The caller should free the returned pointer.
+ */
+static PTOKEN_GROUPS
+GetTokenGroups(const HANDLE token)
+{
+    PTOKEN_GROUPS groups = NULL;
+    DWORD buf_size = 0;
+
+    if (!GetTokenInformation(token, TokenGroups, groups, buf_size, &buf_size)
+        && GetLastError() == ERROR_INSUFFICIENT_BUFFER)
+    {
+        groups = malloc(buf_size);
+    }
+    if (!groups)
+    {
+        MsgToEventLog(M_SYSERR, L"GetTokenGroups");
+    }
+    else if (!GetTokenInformation(token, TokenGroups, groups, buf_size, &buf_size))
     {
-        if (wcscmp(groups[i].lgrui0_name, admin_group[0]) == 0
-            || wcscmp(groups[i].lgrui0_name, admin_group[1]) == 0
-            )
+        MsgToEventLog(M_SYSERR, L"GetTokenInformation");
+        free(groups);
+    }
+    return groups;
+}
+
+/*
+ * Find SID from name
+ *
+ * On input sid buffer should have space for at least sid_size bytes.
+ * Returns true on success, false on failure.
+ * Suggest: in caller allocate sid to hold SECURITY_MAX_SID_SIZE bytes
+ */
+static BOOL
+LookupSID(const WCHAR *name, PSID sid, DWORD sid_size)
+{
+    SID_NAME_USE su;
+    WCHAR domain[MAX_NAME];
+    DWORD dlen = _countof(domain);
+
+    if (!LookupAccountName(NULL, name, sid, &sid_size, domain, &dlen, &su))
+    {
+        return FALSE; /* not fatal as the group may not exist */
+    }
+    return TRUE;
+}
+
+/**
+ * User is in group if the token groups contain the SID of the group
+ * of if the user is a direct member of the group. The latter check
+ * catches dynamic changes in group membership in the local user
+ * database not reflected in the token.
+ * If token_groups or sid is NULL the corresponding check is skipped.
+ *
+ * Using sid and list of groups in token avoids reference to domains so that
+ * this could be completed without access to a Domain Controller.
+ *
+ * Returns true if the user is in the group, false otherwise.
+ */
+static BOOL
+IsUserInGroup(PSID sid, const PTOKEN_GROUPS token_groups, const WCHAR *group_name)
+{
+    BOOL ret = FALSE;
+    DWORD_PTR resume = 0;
+    DWORD err;
+    BYTE grp_sid[SECURITY_MAX_SID_SIZE];
+    int nloop = 0; /* a counter used to not get stuck in the do .. while() */
+
+    /* first check in the token groups */
+    if (token_groups && LookupSID(group_name, (PSID) grp_sid, _countof(grp_sid)))
+    {
+        for (DWORD i = 0; i < token_groups->GroupCount; ++i)
         {
-            MsgToEventLog(M_INFO, TEXT("Authorizing user %s by virtue of membership in group %s"),
-                          username, groups[i].lgrui0_name);
-            ret = TRUE;
-            break;
+            if (EqualSid((PSID) grp_sid, token_groups->Groups[i].Sid))
+            {
+                return TRUE;
+            }
         }
     }
 
-out:
-    if (groups)
+    /* check user's SID is a member of the group */
+    if (!sid)
+    {
+        return FALSE;
+    }
+    do
+    {
+        DWORD nread, nmax;
+        LOCALGROUP_MEMBERS_INFO_0 *members = NULL;
+        err = NetLocalGroupGetMembers(NULL, group_name, 0, (LPBYTE *) &members,
+                                      MAX_PREFERRED_LENGTH, &nread, &nmax, &resume);
+        if ((err != NERR_Success && err != ERROR_MORE_DATA))
+        {
+            break;
+        }
+        /* If a match is already found, ret == TRUE and the loop is skipped */
+        for (int i = 0; i < nread && !ret; ++i)
+        {
+            ret = EqualSid(members[i].lgrmi0_sid, sid);
+        }
+        NetApiBufferFree(members);
+    /* MSDN says the lookup should always iterate until err != ERROR_MORE_DATA */
+    } while (err == ERROR_MORE_DATA && nloop++ < 100);
+
+    if (err != NERR_Success && err != NERR_GroupNotFound)
     {
-        NetApiBufferFree(groups);
+        SetLastError(err);
+        MsgToEventLog(M_SYSERR, TEXT("In NetLocalGroupGetMembers for group '%s'"), group_name);
     }
-    free(tmp);
 
     return ret;
 }