Glibc and System Call Wrappers
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Glibc and System Calls Documentation Release 1.0
Glibc and System Calls Documentation Release 1.0 Rishi Agrawal <[email protected]> Dec 28, 2017 Contents 1 Introduction 1 1.1 Acknowledgements...........................................1 2 Basics of a Linux System 3 2.1 Introduction...............................................3 2.2 Programs and Compilation........................................3 2.3 Libraries.................................................7 2.4 System Calls...............................................7 2.5 Kernel.................................................. 10 2.6 Conclusion................................................ 10 2.7 References................................................ 11 3 Working with glibc 13 3.1 Introduction............................................... 13 3.2 Why this chapter............................................. 13 3.3 What is glibc .............................................. 13 3.4 Download and extract glibc ...................................... 14 3.5 Walkthrough glibc ........................................... 14 3.6 Reading some functions of glibc ................................... 17 3.7 Compiling and installing glibc .................................... 18 3.8 Using new glibc ............................................ 21 3.9 Conclusion................................................ 23 4 System Calls On x86_64 from User Space 25 4.1 Setting Up Arguements......................................... 25 4.2 Calling the System Call......................................... 27 4.3 Retrieving the Return Value...................................... -
The Linux Kernel Module Programming Guide
The Linux Kernel Module Programming Guide Peter Jay Salzman Michael Burian Ori Pomerantz Copyright © 2001 Peter Jay Salzman 2007−05−18 ver 2.6.4 The Linux Kernel Module Programming Guide is a free book; you may reproduce and/or modify it under the terms of the Open Software License, version 1.1. You can obtain a copy of this license at http://opensource.org/licenses/osl.php. This book is distributed in the hope it will be useful, but without any warranty, without even the implied warranty of merchantability or fitness for a particular purpose. The author encourages wide distribution of this book for personal or commercial use, provided the above copyright notice remains intact and the method adheres to the provisions of the Open Software License. In summary, you may copy and distribute this book free of charge or for a profit. No explicit permission is required from the author for reproduction of this book in any medium, physical or electronic. Derivative works and translations of this document must be placed under the Open Software License, and the original copyright notice must remain intact. If you have contributed new material to this book, you must make the material and source code available for your revisions. Please make revisions and updates available directly to the document maintainer, Peter Jay Salzman <[email protected]>. This will allow for the merging of updates and provide consistent revisions to the Linux community. If you publish or distribute this book commercially, donations, royalties, and/or printed copies are greatly appreciated by the author and the Linux Documentation Project (LDP). -
System Calls
System Calls What are they? ● Standard interface to allow the kernel to safely handle user requests – Read from hardware – Spawn a new process – Get current time – Create shared memory ● Message passing technique between – OS kernel (server) – User (client) Executing System Calls ● User program issues call ● Core kernel looks up call in syscall table ● Kernel module handles syscall action ● Module returns result of system call ● Core kernel forwards result to user Module is not Loaded... ● User program issues call ● Core kernel looks up call in syscall table ● Kernel module isn't loaded to handle action ● ... ● Where does call go? System Call Wrappers ● Wrapper calls system call if loaded – Otherwise returns an error ● Needs to be in a separate location so that the function can actually be called – Uses function pointer to point to kernel module implementation Adding System Calls ● You'll need to add and implement: – int start_elevator(void); – int issue_request(int, int, int); – int stop_elevator(void); ● As an example, let's add a call to printk an argument passed in: – int test_call(int); Adding System Calls ● Files to add (project files): – /usr/src/test_kernel/hello_world/test_call.c – /usr/src/test_kernel/hello_world/hello.c – /usr/src/test_kernel/hello_world/Makefile ● Files to modify (core kernel): – /usr/src/test_kernel/arch/x86/entry/syscalls/syscall_64.tbl – /usr/src/test_kernel/include/linux/syscalls.h – /usr/src/test_kernel/Makefile hello_world/test_call.c ● #include <linux/linkage.h> ● #include <linux/kernel.h> ● #include -
Demarinis Kent Williams-King Di Jin Rodrigo Fonseca Vasileios P
sysfilter: Automated System Call Filtering for Commodity Software Nicholas DeMarinis Kent Williams-King Di Jin Rodrigo Fonseca Vasileios P. Kemerlis Department of Computer Science Brown University Abstract This constant stream of additional functionality integrated Modern OSes provide a rich set of services to applications, into modern applications, i.e., feature creep, not only has primarily accessible via the system call API, to support the dire effects in terms of security and protection [1, 71], but ever growing functionality of contemporary software. How- also necessitates a rich set of OS services: applications need ever, despite the fact that applications require access to part of to interact with the OS kernel—and, primarily, they do so the system call API (to function properly), OS kernels allow via the system call (syscall) API [52]—in order to perform full and unrestricted use of the entire system call set. This not useful tasks, such as acquiring or releasing memory, spawning only violates the principle of least privilege, but also enables and terminating additional processes and execution threads, attackers to utilize extra OS services, after seizing control communicating with other programs on the same or remote of vulnerable applications, or escalate privileges further via hosts, interacting with the filesystem, and performing I/O and exploiting vulnerabilities in less-stressed kernel interfaces. process introspection. To tackle this problem, we present sysfilter: a binary Indicatively, at the time of writing, the Linux -
The Evolution of the Unix Time-Sharing System*
The Evolution of the Unix Time-sharing System* Dennis M. Ritchie Bell Laboratories, Murray Hill, NJ, 07974 ABSTRACT This paper presents a brief history of the early development of the Unix operating system. It concentrates on the evolution of the file system, the process-control mechanism, and the idea of pipelined commands. Some attention is paid to social conditions during the development of the system. NOTE: *This paper was first presented at the Language Design and Programming Methodology conference at Sydney, Australia, September 1979. The conference proceedings were published as Lecture Notes in Computer Science #79: Language Design and Programming Methodology, Springer-Verlag, 1980. This rendition is based on a reprinted version appearing in AT&T Bell Laboratories Technical Journal 63 No. 6 Part 2, October 1984, pp. 1577-93. Introduction During the past few years, the Unix operating system has come into wide use, so wide that its very name has become a trademark of Bell Laboratories. Its important characteristics have become known to many people. It has suffered much rewriting and tinkering since the first publication describing it in 1974 [1], but few fundamental changes. However, Unix was born in 1969 not 1974, and the account of its development makes a little-known and perhaps instructive story. This paper presents a technical and social history of the evolution of the system. Origins For computer science at Bell Laboratories, the period 1968-1969 was somewhat unsettled. The main reason for this was the slow, though clearly inevitable, withdrawal of the Labs from the Multics project. To the Labs computing community as a whole, the problem was the increasing obviousness of the failure of Multics to deliver promptly any sort of usable system, let alone the panacea envisioned earlier. -
Lab 1: Loadable Kernel Modules (Lkms)
Lab 1: Loadable Kernel Modules (LKMs) Overview For this lab, we will be interfacing with an LCD screen using the Phytec board. This means we will be creating device drivers for our system to allow it to interact with our hardware. Since our board is running Linux which is a pretty advanced operating system for most embedded devices we will want to accomplish this by appending additional functionality to the working kernel. This is done using loadable kernel modules. Background Before we get too far, here is some important information we will need to know in order to interact with the Linux kernel and perform the functions we want. To write device drivers we must first understand what they are. There are three main types of device drivers; character, block, and network. In this class, we will be writing character device drivers. A character device driver is one that transfers data directly to and from a user process. This is the most common type of device driver. Character device drivers normally perform I/O in a byte stream. They can also provide additional interfaces not present in block drivers, such as I/O control commands, memory mapping, and device polling. Drivers that support a file system are known as block device drivers. Block device drivers take a file system request, in the form of a buffer structure, and issue the I/O operations to the disk to transfer the specified block. Block device drivers can also provide a character driver interface that allows utility programs to bypass the file system and access the device directly. -
Thread Evolution Kit for Optimizing Thread Operations on CE/Iot Devices
Thread Evolution Kit for Optimizing Thread Operations on CE/IoT Devices Geunsik Lim , Student Member, IEEE, Donghyun Kang , and Young Ik Eom Abstract—Most modern operating systems have adopted the the threads running on CE/IoT devices often unintentionally one-to-one thread model to support fast execution of threads spend a significant amount of time in taking the CPU resource in both multi-core and single-core systems. This thread model, and the frequency of context switch rapidly increases due to which maps the kernel-space and user-space threads in a one- to-one manner, supports quick thread creation and termination the limited system resources, degrading the performance of in high-performance server environments. However, the perfor- the system significantly. In addition, since CE/IoT devices mance of time-critical threads is degraded when multiple threads usually have limited memory space, they may suffer from the are being run in low-end CE devices with limited system re- segmentation fault [16] problem incurred by memory shortages sources. When a CE device runs many threads to support diverse as the number of threads increases and they remain running application functionalities, low-level hardware specifications often lead to significant resource contention among the threads trying for a long time. to obtain system resources. As a result, the operating system Some engineers have attempted to address the challenges encounters challenges, such as excessive thread context switching of IoT environments such as smart homes by using better overhead, execution delay of time-critical threads, and a lack of hardware specifications for CE/IoT devices [3], [17]–[21]. -
The UNIX Time- Sharing System
1. Introduction There have been three versions of UNIX. The earliest version (circa 1969–70) ran on the Digital Equipment Cor- poration PDP-7 and -9 computers. The second version ran on the unprotected PDP-11/20 computer. This paper describes only the PDP-11/40 and /45 [l] system since it is The UNIX Time- more modern and many of the differences between it and older UNIX systems result from redesign of features found Sharing System to be deficient or lacking. Since PDP-11 UNIX became operational in February Dennis M. Ritchie and Ken Thompson 1971, about 40 installations have been put into service; they Bell Laboratories are generally smaller than the system described here. Most of them are engaged in applications such as the preparation and formatting of patent applications and other textual material, the collection and processing of trouble data from various switching machines within the Bell System, and recording and checking telephone service orders. Our own installation is used mainly for research in operating sys- tems, languages, computer networks, and other topics in computer science, and also for document preparation. UNIX is a general-purpose, multi-user, interactive Perhaps the most important achievement of UNIX is to operating system for the Digital Equipment Corpora- demonstrate that a powerful operating system for interac- tion PDP-11/40 and 11/45 computers. It offers a number tive use need not be expensive either in equipment or in of features seldom found even in larger operating sys- human effort: UNIX can run on hardware costing as little as tems, including: (1) a hierarchical file system incorpo- $40,000, and less than two man years were spent on the rating demountable volumes; (2) compatible file, device, main system software. -
Red Hat Enterprise Linux for Real Time 7 Tuning Guide
Red Hat Enterprise Linux for Real Time 7 Tuning Guide Advanced tuning procedures for Red Hat Enterprise Linux for Real Time Radek Bíba David Ryan Cheryn Tan Lana Brindley Alison Young Red Hat Enterprise Linux for Real Time 7 Tuning Guide Advanced tuning procedures for Red Hat Enterprise Linux for Real Time Radek Bíba Red Hat Customer Content Services [email protected] David Ryan Red Hat Customer Content Services [email protected] Cheryn Tan Red Hat Customer Content Services Lana Brindley Red Hat Customer Content Services Alison Young Red Hat Customer Content Services Legal Notice Copyright © 2015 Red Hat, Inc. This document is licensed by Red Hat under the Creative Commons Attribution-ShareAlike 3.0 Unported License. If you distribute this document, or a modified version of it, you must provide attribution to Red Hat, Inc. and provide a link to the original. If the document is modified, all Red Hat trademarks must be removed. Red Hat, as the licensor of this document, waives the right to enforce, and agrees not to assert, Section 4d of CC-BY-SA to the fullest extent permitted by applicable law. Red Hat, Red Hat Enterprise Linux, the Shadowman logo, JBoss, MetaMatrix, Fedora, the Infinity Logo, and RHCE are trademarks of Red Hat, Inc., registered in the United States and other countries. Linux ® is the registered trademark of Linus Torvalds in the United States and other countries. Java ® is a registered trademark of Oracle and/or its affiliates. XFS ® is a trademark of Silicon Graphics International Corp. or its subsidiaries in the United States and/or other countries. -
System Calls & Signals
CS345 OPERATING SYSTEMS System calls & Signals Panagiotis Papadopoulos [email protected] 1 SYSTEM CALL When a program invokes a system call, it is interrupted and the system switches to Kernel space. The Kernel then saves the process execution context (so that it can resume the program later) and determines what is being requested. The Kernel carefully checks that the request is valid and that the process invoking the system call has enough privilege. For instance some system calls can only be called by a user with superuser privilege (often referred to as root). If everything is good, the Kernel processes the request in Kernel Mode and can access the device drivers in charge of controlling the hardware (e.g. reading a character inputted from the keyboard). The Kernel can read and modify the data of the calling process as it has access to memory in User Space (e.g. it can copy the keyboard character into a buffer that the calling process has access to) When the Kernel is done processing the request, it restores the process execution context that was saved when the system call was invoked, and control returns to the calling program which continues executing. 2 SYSTEM CALLS FORK() 3 THE FORK() SYSTEM CALL (1/2) • A process calling fork()spawns a child process. • The child is almost an identical clone of the parent: • Program Text (segment .text) • Stack (ss) • PCB (eg. registers) • Data (segment .data) #include <sys/types.h> #include <unistd.h> pid_t fork(void); 4 THE FORK() SYSTEM CALL (2/2) • The fork()is one of the those system calls, which is called once, but returns twice! Consider a piece of program • After fork()both the parent and the child are .. -
SUSE Linux Enterprise Server 12 SP4 System Analysis and Tuning Guide System Analysis and Tuning Guide SUSE Linux Enterprise Server 12 SP4
SUSE Linux Enterprise Server 12 SP4 System Analysis and Tuning Guide System Analysis and Tuning Guide SUSE Linux Enterprise Server 12 SP4 An administrator's guide for problem detection, resolution and optimization. Find how to inspect and optimize your system by means of monitoring tools and how to eciently manage resources. Also contains an overview of common problems and solutions and of additional help and documentation resources. Publication Date: September 24, 2021 SUSE LLC 1800 South Novell Place Provo, UT 84606 USA https://documentation.suse.com Copyright © 2006– 2021 SUSE LLC and contributors. All rights reserved. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or (at your option) version 1.3; with the Invariant Section being this copyright notice and license. A copy of the license version 1.2 is included in the section entitled “GNU Free Documentation License”. For SUSE trademarks, see https://www.suse.com/company/legal/ . All other third-party trademarks are the property of their respective owners. Trademark symbols (®, ™ etc.) denote trademarks of SUSE and its aliates. Asterisks (*) denote third-party trademarks. All information found in this book has been compiled with utmost attention to detail. However, this does not guarantee complete accuracy. Neither SUSE LLC, its aliates, the authors nor the translators shall be held liable for possible errors or the consequences thereof. Contents About This Guide xii 1 Available Documentation xiii -
UNIX History Page 1 Tuesday, December 10, 2002 7:02 PM
UNIX History Page 1 Tuesday, December 10, 2002 7:02 PM CHAPTER 1 UNIX Evolution and Standardization This chapter introduces UNIX from a historical perspective, showing how the various UNIX versions have evolved over the years since the very first implementation in 1969 to the present day. The chapter also traces the history of the different attempts at standardization that have produced widely adopted standards such as POSIX and the Single UNIX Specification. The material presented here is not intended to document all of the UNIX variants, but rather describes the early UNIX implementations along with those companies and bodies that have had a major impact on the direction and evolution of UNIX. A Brief Walk through Time There are numerous events in the computer industry that have occurred since UNIX started life as a small project in Bell Labs in 1969. UNIX history has been largely influenced by Bell Labs’ Research Editions of UNIX, AT&T’s System V UNIX, Berkeley’s Software Distribution (BSD), and Sun Microsystems’ SunOS and Solaris operating systems. The following list shows the major events that have happened throughout the history of UNIX. Later sections describe some of these events in more detail. 1 UNIX History Page 2 Tuesday, December 10, 2002 7:02 PM 2 UNIX Filesystems—Evolution, Design, and Implementation 1969. Development on UNIX starts in AT&T’s Bell Labs. 1971. 1st Edition UNIX is released. 1973. 4th Edition UNIX is released. This is the first version of UNIX that had the kernel written in C. 1974. Ken Thompson and Dennis Ritchie publish their classic paper, “The UNIX Timesharing System” [RITC74].