This PR makes the following changes in the coreSNTP demo:
To suggest the most secure way of using SNTP communication, we are adding a documentation note about the Network Time Security in the SNTP demo.
Hygiene update of using the FreeRTOS/backoffAlgorithm utility library for calculating time polling period interval backoff when time requests are rejected by a time server.
Issue
There is a possible vulnerability of Denial of Service attack by keeping the UDP socket for the SNTP client task always open in the coreSNTP demo. The Denial of Service attack can occur from receiving multiple server response (duplicated or malicious) for a single SNTP time request sent by the client, and thereby, filing the socket network buffer response packets that affect future time requests.
Solution
This PR fixes this vulnerability by updating the demo to keep a UDP socket open only for the time period of waiting for server response, closing the socket on either receiving a server response or experiencing server timeout, and re-creating a UDP socket for the next polling try. This PR also adds another security functionality using a random port for UDP socket to protect against spoofing attacks from "off-network path" attackers.
* Fix code to match comment; idle prioriry task should not block to yield, as then it will hardly run at all (bug affects SMP tests)
* Add RP2040 Demo - can be used for 'main' or 'smp' branch of FreeRTOS_Kernel
* move to latest main/ of FreeRTOS-Kernel
* move RP2040 demos into Community-Supported
* Update whitespace issue
Co-authored-by: Gaurav-Aggarwal-AWS <33462878+aggarg@users.noreply.github.com>
* Add SMP to lexicon
Co-authored-by: Gaurav-Aggarwal-AWS <33462878+aggarg@users.noreply.github.com>
Update the coreSNTP submodule to the latest commit. Also, make updates to the coreSNTP demo for the new changes in the SNTP library which include the following:
1. Update to the type for packet size from size_t to uint16_t for parameters in the transport and authentication interfaces.
2. Change in the call to Sntp_SendTimeRequest API to pass the new blockTimeMs parameter added to the API.
3. Update to the clock-offfset type from int32_t to int64_t for representing information in milliseconds. To accommodate this update in the SntpSetTime_t interface, the mathematical model for representing system clock has been updated to store slew rate as milliseconds/second (instead of second/second). This change improves the accuracy of the WinSim demo time correction (because the milliseconds of time difference between server and client time is corrected over the entire polling interval which makes a significant difference!).
This PR also adds demo config macros for setting the block time values passed to the Sntp_SendTimeRequest and Sntp_ReceiveTimeResponse APIs.
Update the coreSNTP demo to showcase use of symmetric key algorithm of authentication scheme for securing SNTP communication between client and server.
The demo uses the AES-128-CMAC algorithm for the generating Message Authentication Code for the client on sending the SNTP time request to server as well as validating the server response received by verifying if the payload present authentication code can be generated. Use of an authentication mechanism in SNTP communication protects against server spoofing attacks as well as man-in-the-middle attacks of server response modification.
The demo uses corePKCS11 library for the AES-CMAC operations. Also, the demo adds functionality of generating random number, using corePKCS11, for sending as a parameter to the Sntp_SendTimeRequest API.
Note: For symmetric key based security mechanism to be protective against malicious, it is IMPORTANT to securely pre-share the symmetric key between client and server.
Add the FreeRTOS/coreSNTP library as a submodule (along with manifest.yaml file update) and add a demo project to showcase use of the coreSNTP library for having a SNTP client daemon in the system for periodically synchronizing system time with the internet to maintain Coordinated Univeral Time (UTC) in a device. This demo maintains UTC time of system in RAM, thereby, representing systems without a Real-Time Clock (RTC) module in the device.
Note: This demo shows use of coreSNTP library for SNTP communication with NTP/SNTP time servers in non-authenticated mode (i.e. without any security mechanism payload beyond the standard 48 bytes of NTP packet exchange between client-server).
* Added spell check
* All words
* Add a missing word
* Fix header checks
* Fix header checks v1
* Fix header check v2
* Updated freertos link in header
* Fixed afr link in the header
* Fix last of header checks
* Update the spell check script to check amazon licensed files only
* Fixed paths and added comments
* Try with modified repo
* Add inplace substitute option to sed
* Use official repo as the spell checker source
* Add vendor file to the ignored list
Co-authored-by: root <root@ip-172-31-5-28.us-west-2.compute.internal>
tianmc1
Gaurav-Aggarwal-AWS
Archit Aggarwal
Graham Sanderson
Alfred Gedeon
Aniruddha Kanhere