Permit assignment the IPMI management channel via JSON

phosphor-ipmi-host hard codes Channel 1 as the LAN NIC responsible for
managing and updating IPMI, Redfish, and web server access
permissions. Systems that do not have an lan-802.3 channel type
configured for IPMI Channel 1 have no way of assigning permissions
that flow to phosphor-user-manager. The inability to update
permissions within phosphor-user-manaager ultimaltely flows to Redfish
and HTTPS access.

The changes in this commit provide flexibility in assigning the IPMI
channel used to propagate permission changes to
phosphor-user-manager. A new boolean keyword, is_managment_nic, is
added. This entry is added to the JSON file, channel_config.json by
default, to announce which lan-802.3 IPMI channel is to be used to
assign IPMI permissions used by phosphor-user-manager. Only one
channel can have this ability. If the keyword is missing in the JSON
file, the code falls back to using Channel 1.

Tested:
Fully testing this change requires using code that dynamically
disables Channel 1. The SUT only has a single NIC, which is not
assigned to Channel 1.

Fully reprogrammed SPI to enter a pristine state.
Created a new user, channel 3, id 2, privilege=4

Confirmed LAN "ipmitool raw 6 1" succeeds
Confirmed Web access to new user account
Confirmed Redfish acess to new user account
Confirmed BMC console "ipmitool raw 6 1" succeeds

Used BMC console ipmitool to change user permissions from 4 to
15 (i.e. no access)

Confirmed LAN "ipmitool raw 6 1" succeeds
Confirmed Web access to new user account fails
Confirmed Redfish acess to new user account fails
Confirmed BMC console "ipmitool raw 6 1" fails

Used BMC console ipmitool to change user permissions from 15 to
4 (i.e. admin)

All of the prior tests work as expected.

Change-Id: I5f6941fefc4f80742e404de1f22ba10cbedf5d5d
Signed-off-by: Johnathan Mantey <johnathanx.mantey@intel.com>
diff --git a/user_channel/user_mgmt.cpp b/user_channel/user_mgmt.cpp
index 04eb2f9..a1aba71 100644
--- a/user_channel/user_mgmt.cpp
+++ b/user_channel/user_mgmt.cpp
@@ -17,6 +17,7 @@
 
 #include "apphandler.hpp"
 #include "channel_layer.hpp"
+#include "channel_mgmt.hpp"
 
 #include <security/pam_appl.h>
 #include <sys/stat.h>
@@ -509,11 +510,15 @@
 
 uint8_t UserAccess::getUsrMgmtSyncIndex()
 {
-    // TODO: Need to get LAN1 channel number dynamically,
-    // which has to be in sync with system user privilege
-    // level(Phosphor-user-manager). Note: For time being chanLan1 is marked as
-    // sync index to the user-manager privilege..
-    return static_cast<uint8_t>(EChannelID::chanLan1);
+    // Identify the IPMI channel used to assign system user privilege levels
+    // in phosphor-user-manager. The default value is IPMI Channel 1. To
+    // assign a different channel add:
+    //      "is_management_nic" : true
+    // into the channel_config.json file describing the assignment of the IPMI
+    // channels. It is only necessary to add the string above to ONE record in
+    // the channel_config.json file. All other records will be automatically
+    // assigned a "false" value.
+    return getChannelConfigObject().getManagementNICID();
 }
 
 CommandPrivilege UserAccess::convertToIPMIPrivilege(const std::string& value)