The Experts below are selected from a list of 246 Experts worldwide ranked by ideXlab platform
Jin Yin-cheng - One of the best experts on this subject based on the ideXlab platform.
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Design and Implementation of Virtual Machine Firewall Based on SR-IOV
Computer Engineering, 2014Co-Authors: Xun Zhong-kai, Huang Hao, Jin Yin-chengAbstract:Aiming at the problem of low performance caused by frequent switching between user Mode and Kernel Mode, multiple copies of data between the virtual domains through virtual network data transmission, this paper proposes a high performance virtual machine firewall, and it adopts the network packet filtering and high performance of SR-IOV to make virtual domain directly interact with the real network card. Aiming at the problem of vulnerable attack for a lower privilege level virtual domain firewall, it takes higher privilege level of Xen to real-time monitor the virtual machine firewall module and protect it from illegally accessing. Experimental results show that the deployment of SR-IOV network card in the virtual machine firewall makes the network I/O performance increase by 1 time compared with the Xen network I/O assess Mode. The deployment of the monitor module in Xen can successfully prevent the firewall from unauthorized access and malicious tampering, and ensure the safety of the firewall.
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Design and Implementation of Virtual Machine Firewall Based on SR-IOV
2014Co-Authors: Xun Zhong-kai, Huang Hao, Jin Yin-chengAbstract:【Abstract】Aiming at the problem of low performance caused by frequent switching between user Mode and Kernel Mode, multiple copies of data between the virtual domains through virtual network data transmission, this paper proposes a high performance virtual machine firewall, and it adopts the network packet filtering and high performance of SR-IOV to make virtual domain directly interact with the real network card. Aiming at the problem of vulnerable attack for a lower privilege level virtual domain firewall, it takes higher privilege level of Xen to real-time monitor the virtual machine firewall module and protect it from illegally accessing. Experimental results show that the deployment of SR-IOV network card in the virtual machine firewall makes the network I/O performance increase by 1 time compared with the Xen network I/O assess Mode. The deployment of the monitor module in Xen can successfully prevent the firewall from unauthorized access and malicious tampering, and ensure the safety of the firewall. 【Key words】virtualization; Xen Virtual Machine Manager(VMM); SR-IOV specification; firewall; high-performance; monitoring DOI: 10.3969/j.issn.1000-3428.2014.05.032 计 算 机 工 程 Computer Engineering 第 40卷 第 5期 Vol.40 No.5 2014年 5月 May 2014
Henry M Levy - One of the best experts on this subject based on the ideXlab platform.
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improving the reliability of commodity operating systems
ACM Transactions on Computer Systems, 2005Co-Authors: Michael M Swift, Brian N Bershad, Henry M LevyAbstract:Despite decades of research in extensible operating system technology, extensions such as device drivers remain a significant cause of system failures. In Windows XP, for example, drivers account for 85p of recently reported failures.This article describes Nooks, a reliability subsystem that seeks to greatly enhance operating system (OS) reliability by isolating the OS from driver failures. The Nooks approach is practical: rather than guaranteeing complete fault tolerance through a new (and incompatible) OS or driver architecture, our goal is to prevent the vast majority of driver-caused crashes with little or no change to the existing driver and system code. Nooks isolates drivers within lightweight protection domains inside the Kernel address space, where hardware and software prevent them from corrupting the Kernel. Nooks also tracks a driver's use of Kernel resources to facilitate automatic cleanup during recovery.To prove the viability of our approach, we implemented Nooks in the Linux operating system and used it to fault-isolate several device drivers. Our results show that Nooks offers a substantial increase in the reliability of operating systems, catching and quickly recovering from many faults that would otherwise crash the system. Under a wide range and number of fault conditions, we show that Nooks recovers automatically from 99p of the faults that otherwise cause Linux to crash.While Nooks was designed for drivers, our techniques generalize to other Kernel extensions. We demonstrate this by isolating a Kernel-Mode file system and an in-Kernel Internet service. Overall, because Nooks supports existing C-language extensions, runs on a commodity operating system and hardware, and enables automated recovery, it represents a substantial step beyond the specialized architectures and type-safe languages required by previous efforts directed at safe extensibility.
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improving the reliability of commodity operating systems
Symposium on Operating Systems Principles, 2003Co-Authors: Michael M Swift, Brian N Bershad, Henry M LevyAbstract:Despite decades of research in extensible operating system technology, extensions such as device drivers remain a significant cause of system failures. In Windows XP, for example, drivers account for 85% of recently reported failures. This paper describes Nooks, a reliability subsystem that seeks to greatly enhance OS reliability by isolating the OS from driver failures. The Nooks approach is practical: rather than guaranteeing complete fault tolerance through a new (and incompatible) OS or driver architecture, our goal is to prevent the vast majority of driver-caused crashes with little or no change to existing driver and system code. To achieve this, Nooks isolates drivers within lightweight protection domains inside the Kernel address space, where hardware and software prevent them from corrupting the Kernel. Nooks also tracks a driver's use of Kernel resources to hasten automatic clean-up during recovery.To prove the viability of our approach, we implemented Nooks in the Linux operating system and used it to fault-isolate several device drivers. Our results show that Nooks offers a substantial increase in the reliability of operating systems, catching and quickly recovering from many faults that would otherwise crash the system. In a series of 2000 fault-injection tests, Nooks recovered automatically from 99% of the faults that caused Linux to crash.While Nooks was designed for drivers, our techniques generalize to other Kernel extensions, as well. We demonstrate this by isolating a Kernel-Mode file system and an in-Kernel Internet service. Overall, because Nooks supports existing C-language extensions, runs on a commodity operating system and hardware, and enables automated recovery, it represents a substantial step beyond the specialized architectures and type-safe languages required by previous efforts directed at safe extensibility.
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an analysis of operating system behavior on a simultaneous multithreaded architecture
Architectural Support for Programming Languages and Operating Systems, 2000Co-Authors: Joshua Redstone, Susan J Eggers, Henry M LevyAbstract:This paper presents the first analysis of operating system execution on a simultaneous multithreaded (SMT) processor. While SMT has been studied extensively over the past 6 years, previous research has focused entirely on user-Mode execution. However, many of the applications most amenable to multithreading technologies spend a significant fraction of their time in Kernel code. A full understanding of the behavior of such workloads therefore requires execution and measurement of the operating system, as well as the application itself.To carry out this study, we (1) modified the Digital Unix 4.0d operating system to run on an SMT CPU, and (2) integrated our SMT Alpha instruction set simulator into the SimOS simulator to provide an execution environment. For an OS-intensive workload, we ran the multithreaded Apache Web server on an 8-context SMT. We compared Apache's user- and Kernel-Mode behavior to a standard multiprogrammed SPECInt workload, and compared the SMT processor to an out-of-order superscalar running both workloads. Overall, our results demonstrate the microarchitectural impact of an OS-intensive workload on an SMT processor and provide insight into the OS demands of the Apache Web server. The synergy between the SMT processor and Web and OS software produced a greater throughput gain over superscalar execution than seen on any previously examined workloads, including commercial databases and explicitly parallel programs.
Xun Zhong-kai - One of the best experts on this subject based on the ideXlab platform.
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Design and Implementation of Virtual Machine Firewall Based on SR-IOV
Computer Engineering, 2014Co-Authors: Xun Zhong-kai, Huang Hao, Jin Yin-chengAbstract:Aiming at the problem of low performance caused by frequent switching between user Mode and Kernel Mode, multiple copies of data between the virtual domains through virtual network data transmission, this paper proposes a high performance virtual machine firewall, and it adopts the network packet filtering and high performance of SR-IOV to make virtual domain directly interact with the real network card. Aiming at the problem of vulnerable attack for a lower privilege level virtual domain firewall, it takes higher privilege level of Xen to real-time monitor the virtual machine firewall module and protect it from illegally accessing. Experimental results show that the deployment of SR-IOV network card in the virtual machine firewall makes the network I/O performance increase by 1 time compared with the Xen network I/O assess Mode. The deployment of the monitor module in Xen can successfully prevent the firewall from unauthorized access and malicious tampering, and ensure the safety of the firewall.
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Design and Implementation of Virtual Machine Firewall Based on SR-IOV
2014Co-Authors: Xun Zhong-kai, Huang Hao, Jin Yin-chengAbstract:【Abstract】Aiming at the problem of low performance caused by frequent switching between user Mode and Kernel Mode, multiple copies of data between the virtual domains through virtual network data transmission, this paper proposes a high performance virtual machine firewall, and it adopts the network packet filtering and high performance of SR-IOV to make virtual domain directly interact with the real network card. Aiming at the problem of vulnerable attack for a lower privilege level virtual domain firewall, it takes higher privilege level of Xen to real-time monitor the virtual machine firewall module and protect it from illegally accessing. Experimental results show that the deployment of SR-IOV network card in the virtual machine firewall makes the network I/O performance increase by 1 time compared with the Xen network I/O assess Mode. The deployment of the monitor module in Xen can successfully prevent the firewall from unauthorized access and malicious tampering, and ensure the safety of the firewall. 【Key words】virtualization; Xen Virtual Machine Manager(VMM); SR-IOV specification; firewall; high-performance; monitoring DOI: 10.3969/j.issn.1000-3428.2014.05.032 计 算 机 工 程 Computer Engineering 第 40卷 第 5期 Vol.40 No.5 2014年 5月 May 2014
Benny Pinkas - One of the best experts on this subject based on the ideXlab platform.
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Cryptanalysis of the random number generator of the Windows operating system
ACM Transactions on Information and System Security, 2009Co-Authors: Leo Dorrendorf, Zvi Gutterman, Benny PinkasAbstract:The PseudoRandom Number Generator (PRNG) used by the Windows operating system is the most commonly used PRNG. The pseudorandomness of the output of this generator is crucial for the security of almost any application running in Windows. Nevertheless, its exact algorithm was never published. We examined the binary code of a distribution of Windows 2000. This investigation was done without any help from Microsoft. We reconstructed the algorithm used by the pseudorandom number generator (namely, the function CryptGenRandom). We analyzed the security of the algorithm and found a nontrivial attack: Given the internal state of the generator, the previous state can be computed in 223 steps. This attack on forward security demonstrates that the design of the generator is flawed, since it is well known how to prevent such attacks. After our analysis was published, Microsoft acknowledged that Windows XP is vulnerable to the same attack. We also analyzed the way in which the generator is used by the operating system and found that it amplifies the effect of the attack: The generator is run in user Mode rather than in Kernel Mode; therefore, it is easy to access its state even without administrator privileges. The initial values of part of the state of the generator are not set explicitly, but rather are defined by whatever values are present on the stack when the generator is called. Furthermore, each process runs a different copy of the generator, and the state of the generator is refreshed with system-generated entropy only after generating 128KB of output for the process running it. The result of combining this observation with our attack is that learning a single state may reveal 128KB of the past and future output of the generator. The implication of these findings is that a buffer overflow attack or a similar attack can be used to learn a single state of the generator, which can then be used to predict all random values, such as SSL keys, used by a process in all its past and future operations. This attack is more severe and more efficient than known attacks in which an attacker can only learn SSL keys if it is controlling the attacked machine at the time the keys are used.
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cryptanalysis of the random number generator of the windows operating system
IACR Cryptology ePrint Archive, 2007Co-Authors: Leo Dorrendorf, Zvi Gutterman, Benny PinkasAbstract:The pseudo-random number generator (PRNG) used by the Windows operating system is the most commonly used PRNG. The pseudo-randomness of the output of this generator is crucial for the security of almost any application running in Windows. Nevertheless, its exact algorithm was never published. We examined the binary code of a distribution of Windows 2000, which is still the second most popular operating system after Windows XP. (This investigation was done without any help from Microsoft.) We reconstructed, for the first time, the algorithm used by the pseudorandom number generator (namely, the function CryptGenRandom). We analyzed the security of the algorithm and found a non-trivial attack: given the internal state of the generator, the previous state can be computed in O(2) work (this is an attack on the forward-security of the generator, an O(1) attack on backward security is trivial). The attack on forward-security demonstrates that the design of the generator is flawed, since it is well known how to prevent such attacks. We also analyzed the way in which the generator is run by the operating system, and found that it amplifies the effect of the attacks: The generator is run in user Mode rather than in Kernel Mode, and therefore it is easy to access its state even without administrator privileges. The initial values of part of the state of the generator are not set explicitly, but rather are defined by whatever values are present on the stack when the generator is called. Furthermore, each process runs a different copy of the generator, and the state of the generator is refreshed with system generated entropy only after generating 128 KBytes of output for the process running it. The result of combining this observation with our attack is that learning a single state may reveal 128 Kbytes of the past and future output of the generator. The implication of these findings is that a buffer overflow attack or a similar attack can be used to learn a single state of the generator, which can then be used to predict all random ∗Research supported in part by the Israel Science Foundation (grant number 860/06).
Huang Hao - One of the best experts on this subject based on the ideXlab platform.
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Design and Implementation of Virtual Machine Firewall Based on SR-IOV
Computer Engineering, 2014Co-Authors: Xun Zhong-kai, Huang Hao, Jin Yin-chengAbstract:Aiming at the problem of low performance caused by frequent switching between user Mode and Kernel Mode, multiple copies of data between the virtual domains through virtual network data transmission, this paper proposes a high performance virtual machine firewall, and it adopts the network packet filtering and high performance of SR-IOV to make virtual domain directly interact with the real network card. Aiming at the problem of vulnerable attack for a lower privilege level virtual domain firewall, it takes higher privilege level of Xen to real-time monitor the virtual machine firewall module and protect it from illegally accessing. Experimental results show that the deployment of SR-IOV network card in the virtual machine firewall makes the network I/O performance increase by 1 time compared with the Xen network I/O assess Mode. The deployment of the monitor module in Xen can successfully prevent the firewall from unauthorized access and malicious tampering, and ensure the safety of the firewall.
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Design and Implementation of Virtual Machine Firewall Based on SR-IOV
2014Co-Authors: Xun Zhong-kai, Huang Hao, Jin Yin-chengAbstract:【Abstract】Aiming at the problem of low performance caused by frequent switching between user Mode and Kernel Mode, multiple copies of data between the virtual domains through virtual network data transmission, this paper proposes a high performance virtual machine firewall, and it adopts the network packet filtering and high performance of SR-IOV to make virtual domain directly interact with the real network card. Aiming at the problem of vulnerable attack for a lower privilege level virtual domain firewall, it takes higher privilege level of Xen to real-time monitor the virtual machine firewall module and protect it from illegally accessing. Experimental results show that the deployment of SR-IOV network card in the virtual machine firewall makes the network I/O performance increase by 1 time compared with the Xen network I/O assess Mode. The deployment of the monitor module in Xen can successfully prevent the firewall from unauthorized access and malicious tampering, and ensure the safety of the firewall. 【Key words】virtualization; Xen Virtual Machine Manager(VMM); SR-IOV specification; firewall; high-performance; monitoring DOI: 10.3969/j.issn.1000-3428.2014.05.032 计 算 机 工 程 Computer Engineering 第 40卷 第 5期 Vol.40 No.5 2014年 5月 May 2014
