1. Zephyr Kernel Security Discussion
Jan 11, 2017

2. Security Levels 5 4 3 2b 2a 1 Application Libraries RNG Secure Storage… … 3 2b
Secure OS Subsystems (Logging/FS/) 2a
Secure Infrastructure (Security Objects: Key Objects, TEE)
Kernel + Thread Separation 1
Not Secure: Kernel without thread separation

3. Threads “Stack area” Control block (struct k_thread) Stack
CRC protection?
“Stack area”
Control block (struct k_thread)
Execution flags
Thread state
Init data
Abort function …
Stack
Stack pointer (?)
Data
CRC protection?
MMU/MPU

4. Interrupts
???

5. Scheduler (struct _kernel)
CRC protection?
CPU registers
Store/load
List of threads
Current thread
Priorities
States
Locking
+ Extra Protection for special threads
Idle Thread
Main Thread,
e.g. against DOS (thread starvation)
Flow protection
CRC protection?
Flow protection

6. Memory Allocation Types Global/per thread? Memory Slabs Memory Pools
Heap Memory Pool
Global/per thread?
MMU/MPU
Protected sections

7. Data Passing Key points for consideration: Key goal(s):
Integrity protection
Access control (MPU)
Key goal(s):
Limit accessibility to communicating parties only
Add “protected” counter-parts that sacrifice code size/performance for e.g. integrity protection