Key match logic for key-controlled protection | IBM 10 SP1 EAL4

5.5.2.4.8.3Key-controlled protection

When an access attempt is made to an absolute address, which refers to a memory location, key-controlled protection is applied. Each 4K page, real memory location, has a 7-bit storage key associated with it. These storage keys for pages can only be set when the processor is in the supervisor state. The Program Status Word contains an access key corresponding to the current running program. Key-controlled protection is based on using the access key and the storage key to evaluate whether access to a specific memory location is granted.

The 7-bit storage key consists of access control bits (0, 1, 2, and 3), fetch protection bit (4), reference bit (5), and change bit (6). The following two diagrams show the key-controlled protection process.

Figure 5-56: Key match logic for key-controlled protection

The z/Architecture allows for fetch protection override for key-controlled protection. The following diagram describes how fetch protection override can be used. Currently, SLES does not set the fetch protection bit of the storage key.

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IBM 10 SP1 EAL4 manual Key match logic for key-controlled protection

Contents

Page EJR Table of Contents 2.1 DAC AppArmor Programs with software privilege Permission bits Access Control Lists 100 142 175 207 250 252 269 Terminology Purpose of this documentDocument overview Conventions used in this document System Overview High-level product overview Product historySuse Linux Enterprise Server EServer systems Overall structure of the TOE EServer host computer structurePage EServer system structure TOE services Security policy Local and network services provided by Sles TSF interfaces Operation and administration Approach to TSF identification Page Page System x hardware overview System x hardware architecture System System p hardware overview System pSystem p hardware architecture System z hardware overview System z hardware architecture System z EServer 326 hardware overview EServerEServer 326 hardware architecture AMD x86-64 architecture in compatibility mode Page Hardware privilege Hardware and software privilegePrivilege level Levels of Privilege Software privilege AppArmor 2.1 DAC Programs with software privilege TOE Security Functions software structure Kernel TSF software Logical kernel subsystems and their interactions Logical components Base kernel Execution componentsKernel threads Kernel modules and device drivers Non-kernel TSF softwarePage Definition of subsystems for the CC evaluation TSF databases Trusted process subsystems HardwareFirmware Kernel subsystems User-level audit subsystem Page File and I/O management Functional descriptions Ext3 and CD-ROM file systems before mounting Virtual File System Ext3 and CD-ROM file systems after mounting Pathname translation VFS pathname translation and access control checks Open Mount WriteShared subtrees 2.1 Ext3 file system Disk-based file systemsExtended Attributes Data structures Page Page Data structures and algorithms ISO 9660 file system for CD-ROM Procfs Pseudo file systemsTmpfs Devpts SysfsRootfs Binfmtmisc Discretionary Access Control DACConfigfs Inotify Indicates read Permission bits Types of ACL tags Access Control ListsACL qualifier Aclmask Default ACLs and ACL inheritanceACL permissions Relationship to file permission bits ACL enforcement 7 I/O scheduler Asynchronous I/O Anticipatory I/O scheduler Deadline I/O schedulerCompletely Fair Queuing scheduler Bottom halves 8 I/O interruptsNoop I/O scheduler Top halves Work queue Processor interruptsMachine check Tasklets Data structures Process control and managementPage Control of child processes Process creation and destructionDAC controls Execve Process switchKernel threads Setresuidand setresgid Hyperthreading scheduler Scheduling 14 Hyperthreaded scheduling Kernel preemption Inter-process communication Data structures and algorithms Pipes Fifo creation First-In First-Out Named pipes Fifo open System V IPCCommon data structures Message queues Common functions Semaphores Shared memory regions Algorithms SignalsSockets Data structures 16 Object reuse handling in socket allocation Network subsystem Overview of the network protocol stack 18 How data travels through the Network protocol stack Network layer protocols Transport layer protocols 3.2.2 IPv6 Header Addressing IP Security IPsec Flow LabelsSecurity Transition between IPv4 and IPv6 AH Header Functional Description of IPsec An IP Packet with tunnel mode AH An IP Packet with tunnel mode ESP Link layer protocols Internet Control Message Protocol Icmp Address Resolution Protocol ARP Network services interface Bind Socket Accept ListenConnect Memory management Access controlGeneric calls Page 24 Previous three-level page-tables architecture Four-Level Page Tables System Memory addressing 26 System x virtual addressing space Segmentation 28 Access control through segmentation Paging 30 Regular paging 32 Access control through paging For more information about call gates, refer to System p 33 Paging data structures 34 Logical partitions Privilege State 36 Determination of processor mode in Lpar Address Translation on LPARs Real mode addressingHypervisor Access to I/O address space Virtual mode addressingDirect Memory Access addressing Preventing denial of service Run-Time Abstraction ServicesSystem p native mode 39 Effective address Machine State Register 41 Block address Segment descriptor DescriptorBlock descriptor Address translation mechanisms 45 Block Address Translation entry Address Translation and access control 47 Block Address Translation access controlPage 48 Page Address Translation and access control System z Native hardware modeLpar mode 2.4.3 z/VM Guest mode Address spaces Address sizesAddress translations 49 System z address types and their translation 51 Address translation modes 52 64-bit or 31-bit Dynamic Address Translation 53 Low-address protection on effective address Memory protection mechanisms Table protection 113 114 56 Key match logic for key-controlled protection Logical address EServer Linear address Effective addressPhysical address 59 Data access privilege checks Access control through type check Page 121 63 Page map level four entry Translation Lookaside Buffers Kernel memory management Reverse map Virtual Memory Support for Numa servers Huge Translation Lookaside Buffers 65 Rmap VM 66 TLB Operation Frame management Remapfilepages Memory area management Process address spaceNoncontiguous memory area management 68 Object reuse handling while allocating new linear address Atomic operations Symmetric multiprocessing and synchronizationMemory barriers Kernel semaphores Audit subsystemAudit components Spin locks Kernel-userspace interface Audit kernel components Filesystem watches Syscall auditingTask structure Audit context fields 71 Task Structure File system audit components User space audit components Configuration Audit operation and configuration options Option Description Possible values Operation Audit record generation Audit recordsKernel record generation Syscall audit record generation 73 Audit Record Generation File system audit record generation 74 Extension to system calls interface Record generation by trusted programs Socket call and IPC audit record generationAudit record format Page Event Description LAF audit events Auditctl Login uid associationAudit tools Kernel modules Linux Security Module framework Structure LSM AppArmor module LSM capabilities moduleAppArmor Var/log/boot.msg Rwl Var/run/klogd.pid AppArmor administrative utilities Securityfs AppArmor access control functions 1 I/O virtualization on System z Device driversInterpretive-execution facility State description Hardware virtualization and simulation Character device driver Block device driver Init System initialization System Boot loader Boot methodsBoot process Linuxrc 79 System x Sles boot sequence System p Page System p in Lpar 80 System p Sles boot sequence Etc/sysconfig/init script 81 System p Lpar Sles boot sequence Control program System z 82describes the boot process for Sles as a z/VM guest EServer 82 System z Sles boot sequence 169 83schematically describes the boot process of eServer 170 83 eServer 326 Sles boot sequence Identification and authentication Overview Pluggable Authentication Module Modules Configuration terminology Etc/security/pamenv.conf Protected databases Agetty Trusted commands and trusted processesAccess control rules 11.2.1.1 DAC Gpasswd Login Newgrp Mingetty 11.3.7 su Passwd Network applications Interaction with auditOpenSSL Secure socket-layer interface 84 SSL location in the network stack Encryption Concepts 87 Encryption Algorithm and Key 88 Asymmetric keys SSL architecture Message Authentication Code MACMessage digest Digital certificates and certificate authority SSL handshake protocol 90 SSL Protocol 187 Symmetric ciphers OpenSSL algorithms Certificates Asymmetric ciphersHash functions Secure Shell SSH server daemon SSH client Cups Very Secure File Transfer Protocol daemon Cupsd Ping6 PingOpenssl Stunnel Chage System managementAccount Management Xinetd Chsh Chfn Useradd User managementUsermod Userdel Groupadd Group management Groupdel Groupmod 202 Hwclock System Time managementOther System Management Date 13.5.1.3 I/O controller and network Supervisor mode instructionsMemory Memory separation System p Star Amtu output 207 13.6 I&A support Batch processing user commandsBatch processing 14.1.2 at Cron Batch processing daemons14.2.2 atd Aureport User-level audit subsystemAudit daemon Audit utilities Audit logs Audit configuration filesAutrace TSF libraries Supporting functions LibraryDescription System call linking mechanism Library linking mechanism System call argument verification Pageoffset Audit Object reuse Discretionary Access ControlSecurity management TSF protection Secure communications Internal TOE protection mechanisms TP.6 Testing the TOE protection mechanisms TP.7Trusted processes TP.4 TSF Databases TP.5 Kernel subsystem file and I/O Summary of kernel subsystem interfacesExternal Interfaces Internal function Interfaces defined Internal Interfaces 1.1.3 External interfaces system calls Kernel subsystem process control and management Kernel subsystem inter-process communication Internal Interfaces Dopipe Kernel subsystem memory management Kernel subsystem networking Internal interfaces Kernel subsystem audit Kernel subsystem device drivers Other functions Kernel subsystems kernel modules Summary of trusted processes interfaces References RSA 234