CS 550-395

1. CS 550-395 Solaris Operating Environment (The story behind the Solaris OS) Arjun Shankar

2. Introduction • Solaris is the computer operating system that Sun Microsystems provides for its family of Scalable Processor Architecture (SPARC) based processors as well as for Intel-based processors • Features of Solaris: • Its availability • Its scalability • It is built for network computing • It includes security features

3. Better by Design —The Solaris Operating Environment • SolarisTM Design Principles • designed for performance, and reliability; to scale and evolve as business needs change, and to easily support new hardware architectures as they become available • not requiring error-prone major re-writes from one release to the next that decrease reliability • easily ports to a wide range of platforms — giving users choice in computing infrastructure ranging from single and multiprocessor Intel systems to high-end products like the 64-processor Sun Starfire server

4. Designed to Evolve • It has a core infrastructure that is constructed using modular, well-defined, stable interfaces that support the addition of new devices, software libraries, and even file systems. • The operating environment is built with a small kernel that provides the core set of features required by applications, the CDE windowing system, and their shared libraries. • The kernel runs in protected mode and — by keeping its size small. • This results in a system that is much more reliable than those which incorporate too many features in the operating system itself

5. Reliability by Design • with a small, compact kernel that limits the exposure to errors that can bring a system down. • Sun designed the Solaris environment with a clear distinction between the kernel, shared libraries, and applications which further limits the impact of application failures • Designed for the Internet • The Solaris environment supports the IETF-standard Kerberos for user authentication, resulting in superior security when compared to Windows NT proprietary challenge-response authentication

6. Objects Of Execution • Threads and SMPS • Solaris employs a set of kernel threads to handle interrupts. As with any kernel thread, an interrupt thread has its own identifier, priority, context and stack. • The kernel controls access to data structures and synchronizes among interrupt threads using mutex exclusion primitives, i.e. the normalization techniques for threads are used in handling interrupts • Interrupt threads are assigned higher priorities than all other types of kernel threads

7. Fully Preemptable, Multithreaded Kernel • A fully symmetric operating system that allows multiple processors to execute simultaneously within the single, memory-resident image of the kernel • Because the kernel is multithreaded, it is fully preemptable, ensuring that high priority real-time threads can immediately preempt lower priority threads running in user or kernel mode • Extensive use of spin-locks rather than kernel preemption points means that kernel threads typically spin rather than blocking when operating on critical sections of code, thereby improving scalability

8. Solaris's Kernel Design • The basic design was further developed by subdividing the kernel-level objects of execution into smaller user-level objects of execution.  • These user-level objects are unknown to the operating system kernel and thus are not executable on their own.  • They are usually scheduled by the application programmer or a system library to execute in the context of a kernel-level object of execution • The operating systems use a priority-based, time-sliced, preemptive multitasking algorithm to schedule their kernel-level objects.  Each kernel-level object may be either interleaved on a single processor or execute in parallel on multiprocessors

9. Solaris's LWPs and Threads • A lightweight process (LWP) is Solaris's smallest kernel-level object of execution • A Solaris process consists of one or more lightweight processes • In Solaris, a thread is the smallest user-level object of execution • Solaris's threads are implemented and controlled by a system library • One or more threads can be mapped to a lightweight process • The library or the application programmer determines the mapping • Since the threads execute in the context of a lightweight process, the operating system kernel is unaware of their existence • The kernel is only aware of the LWPs that threads execute on • Solaris's thread library defines two types of threads according to schedulinga). Bound thread b). Unbound Thread

10. Execution components of the Solaris Operating Environment

11. The relationships of a process and its LWPs and threads in Solaris

12. Solaris Thread Synchronization Primitives • Mutual Exclusion Lock • Semaphores • Readers/ Writes Lock • Condition Variables

13. Solaris Memory Management • The Least Recently Used Paging Algorithm • Priority Paging • The Solaris 8 Cyclical Page Cache • Higher Page Reclaims - This is considered normal during heavy file system activity • Higher Free Memory Values- The amount of free memory will be higher, since the free memory count now includes a large component of the file system cache  • Zero Scan Rates - Scan rates will be almost zero, unless there is a shortage of system wide available memory

14. Java Applications Development • Real-Time Java Implementation • The Java 2 SDK is bundled with the Solaris 8 Operating Environment, and provides both essential development tools required for creating applications in the Java language and a high-performance, scalable runtime environment. • A full real-time Java implementation will require a real-time Java virtual machine. The on-going Java Community Process is currently defining an open specification for a real-time Java virtual machine

15. Solaris: The Secure Solution Four dimensions of Solaris Security

16. Level 1: Controlling Login Access on Solaris • The first level of Solaris security control consists of features and tools that help administrators tightly control who can log in to the system. • Password validation •Password qualification • Password aging •Shadow password file • Disallow old password •Account expiration • further login restrictions for Solaris are imposed by: • Restricting hours of access • Disable login on repeated invalid attempts • Autolockscreen and logout • Increased controls over root/su privilege

17. Level 2: System Resource Access Control • Solaris includes the Automated Security Access Tool • Existence of a system EEPROM password which protects an unauthorized individual from booting the system in single user mode • Insecure use of the UMASK variable which dictates the default setting for file permissions when a file is created • Insecure use of the PATH variable which outlines the order in which directories will be searched for a specified executable command or program • System file permission settings • Existence of new setuid programs • Home directory permissions

18. Level 3: Secure Distributed Services and Developer Platforms • The Solaris core operating environment incorporates the ONC+TM family of distributed services which can optionally be configured to run with additional security features enabled. • When this is the case, ONC+ consists of the Secure NIS+ distributed naming service, the Secure NFSTM distributed file service, and the Secure Transport Independent Remote Procedure Call (TI-RPC) platform (also known simply as Secure RPC) for building distributed applications and services. • Sun also provides the DCE family of services in an unbundled product called DCE for Solaris. Both secure ONC+ and DCE services rely on foundation technology described in this section.

19. Level 4: Controlling Access to the Physical Network • it was assumed that sites (and users) connected to the network were largely trustable • In addition to potential threats from outsiders, well-intentioned internal users might accidentally expose corporate data or services from within a network to the outside world • Sun supports this level of service - Solaris with its unbundled Solstice FireWall-1 and Solstice Sunscreen products

20. Solaris - Ahead Today, Ahead Tomorrow • The Solaris Operating Environment was built from day one to be networked, using industry standard protocols that provide the interoperability that is the cornerstone of the Internet. • With the most evolvable, scalable, mature, reliable, portable, easily-configured and networked operating environment available, enterprises that wish to maintain their competitive edge today and in the future are choosing the Solaris Operating Environment.