Access Control: Difference between revisions
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Acorn Risc Machine (ARM) |
====Acorn Risc Machine (ARM)==== |
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*most commonly licensed to third-party vendors of embedded systems |
*most commonly licensed to third-party vendors of embedded systems |
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*hardware protection can be customized |
*hardware protection can be customized |
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Security Processors |
====Security Processors==== |
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*hardware security support for cryptography and access control |
*hardware security support for cryptography and access control |
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==Operating Systems== |
==Operating Systems== |
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*access control for files and processes, ring management, IO-management, memory, processors s.o. as deep as the hardware permits it |
*access control for files and processes, ring management, IO-management, memory, processors s.o. as deep as the hardware permits it |
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Do it by groups and/or roles ! |
Do it by groups and/or roles ! |
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===Groups and Roles=== |
===Groups and Roles=== |
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*every user fits into one or some categories |
*every user fits into one or some categories |
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There‘s no final definition. |
There‘s no final definition. |
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===Access Control Lists=== |
===Access Control Lists=== |
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*just one column of the access control matrix stored for every resource |
*just one column of the access control matrix stored for every resource |
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*more attributes (take ownership, change permission, delete) |
*more attributes (take ownership, change permission, delete) |
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*arrangement in domains with trust between them |
*arrangement in domains with trust between them |
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===Capabilities=== |
===Capabilities=== |
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*just one row of the access control matrix stored for every resource |
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*some experimental implementatios in the 70s |
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*today a comeback in the form of public key certificates |
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====Win 2k/XP==== |
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*used combined with ACL |
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*group policies |
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*active directory |
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===Understands=== |
===Understands=== |
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{| |
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|Granularity |control access at the right level |
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file access ↔ database file |
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different systems, different access controls |
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|- |
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|Sandboxing |access to a restricted environment |
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|- |
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|Proof-Carrying-Code |tests the behaviour of a program |
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|- |
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|Object Request Brokers |controlling calls for several objects/resources |
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|} |
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Revision as of 12:35, 14 December 2004
Who and what has access to which resource has to be controled on every IT System.
Introduction
Controlled are issues like
- access to files
- access to memory
- execution of programs
- sharing data with other principals
Access is controlled at different levels:
- application
- middleware
- operating system
- hardware
The complexity of administering Access Control is growing complexity.
Hardware Protection
Protection Problem: preventing one process from interfering with another
Confinement Problem: preventing programs communicating outwards through other than authorized channels (e.g. memory overwriting)
Intel 80x86 (Pentium) Processors
| 8088/8086: | any running program controlled the whole machine |
| 80286: | protected segment addressing and rings, operating systems could run proper |
| 80386: | built-in virtual memory and large memory segments, treated as a 32-bit flat-address machine |
Rings
- process in ring 0 (kernel) manages privilege level of other processes
- ring 1, 2 usually system processes (e.g. win32 subsys, virtual DOS)
- ring 3 user programs
- gates between rings for executing code at an other level
Other Procssors
Acorn Risc Machine (ARM)
- most commonly licensed to third-party vendors of embedded systems
- 32-bit processor
- separate banks of registers for user and system processes
- hardware protection can be customized
Security Processors
- hardware security support for cryptography and access control
- authorized state
- password covered memory access
s.o.
Operating Systems
- access control for files and processes, ring management, IO-management, memory, processors s.o. as deep as the hardware permits it
- matrix is often used to manage this
- not usable for large organizations, because the administration becomes to difficult for humans
Do it by groups and/or roles !
Groups and Roles
- every user fits into one or some categories
- rights have to be defined for these categories
- user gets role and fits in group
What is the difference ?
There‘s no final definition.
Access Control Lists
- just one column of the access control matrix stored for every resource
- not very performant
- difficult to administrate
Unix
- simple list: owner, group, world for user – not for programs
- indirect method for programs: SUID and SGID
- or by user dummy
Win NT
- more attributes (take ownership, change permission, delete)
- arrangement in domains with trust between them
Capabilities
- just one row of the access control matrix stored for every resource
- some experimental implementatios in the 70s
- today a comeback in the form of public key certificates
Win 2k/XP
- used combined with ACL
- group policies
- active directory
Understands
| control access at the right level
file access ↔ database file different systems, different access controls |
| access to a restricted environment |
| tests the behaviour of a program |
| controlling calls for several objects/resources |
Problems
problem if any level doesn’t controll access