The operating system OpenBSD is well-known for its focus on computer security and the development of a multiplicity of safety functions.

Programming interfaces and API changes

The character string functions common in the programming language C strcpy and to be strcat often wrongly uses, which can lead to errors and safety gaps. The existing alternatives strncpy and, Manpages strncat: strncpy and strncat. it is not ideal why the OpenBSD developers Todd C created. Miller and Theo de Raadt strlcpy and strlcat functions. Manpages: strlcpy and strlcat. These are aligned to higher security and offer a konsistenteren replacement for strncat and strncpy. They make it heavier for programmers to leave buffers vulnerable undermined and thus for buffer over runs. Miller, Todd C. and Theo de Raadt. strlcpy and strlcat -, safe, stringer CoPy and concatenation consistent. Proceedings of the USENIX Annual Technical Conference, 6. - 11 June, 1999, pp. 175178. These functions were taken over by the Net and FreeBSD projects, were not accepted however for the GNU C library. Their Maintainer Ulrich Drepper opposes vehement its integration, with the argument, memcpy is an equivalent solution for the Probleme.Depper, Ulrich. Mail to libc alpha: RH: PATCH: safe stringer CoPy and concetation (sic), 8 August 2000. That OpenBSD left ones was changed, in order to spend a warning, if uncertain functions are strcat used as strcpy or. This applies also to other functions, which manipulate character strings and frequently cause problems - for example sprintf. All occurrences of these were replaced in the OpenBSD source code. In addition the guideline was introduced to patchen each occurrence to the package management system. Additionally a static software test is contained in OpenBSD, with which is tried to find other common programming errors with compiling. Madhavapeddy, Anil. Mail too openbsd cvs: CVS: cvs.openbsd.org: src, 6 June 2003. Further programming interfaces developed by the OpenBSD project on security are issetugid and arc4random. Manpages: issetugid and arc4random.

Storage protection

OpenBSD contains some techniques, which help to protect the operating system against attacks by buffer over runs and

Pro policy pro policy web page: here. one of Hiroaki Etoh is developed extension of the GCC, which protects programs against attacks on the push-pop stack (stack smashing) by extended storage protection. Around this to make possible it makes a set of changes: local stack variable are again arranged, so that buffers are platziert after pointers - this protects them in case of a buffer overflow against falsification. Pointers on function arguments are platziert before local buffers; a Canary value is set after local buffers: As soon as the function ends can the Canary is used, in order to determine buffer over runs. Pro policy decides automatically on the basis a heuristic, which analyzes the vulnerability of a buffer whether he is protected this buffer. Pro policy was accepted in December 2002 to the OpenBSD GCC and made for the first time available with version 3.3. The protection is used since OpenBSD 3,4 for the Kernel. The extension functioned on all architectures by OpenBSD to be supported and is according to standard activated. Thus each C-program without user interference is protected.

In May 2004 OpenBSD on Sparc architecture received further push-pop stack protection by StackGhost. This helps to prevent with functions of the Sparc architecture the utilization from buffer overflowing to. Frantzen, Mike and Mike Shuey. StackGhost: Hardware Facilitated stack Protection. Proceedings 10. USENIX Security of symposium, 13. - 17 August 2001, pp. 5566. Support for 64-Bit Sparc was added in March 2005.

To OpenBSD 3,4 W^X (abbreviation for Writeable xor eXecutable) was introduced. It concerns a store management however never guarantees itself that memory is executable either only writing or only, both. This offers an additional protective layer against buffer over runs. Although this can be realized relatively simply on a platform such as amd64, which offers hardware support for that NX bit, OpenBSD is one of the few operating systems, which this supports also on the usual i386 architecture.

the development phase for version 3.8 changes at the store management function were made malloc. In traditional Unix operating systems malloc memory reserves, by extending the Unix data segment. This procedure made the realization more difficult of a strong protection against safety problems. The current malloc conversion to OpenBSD uses mmap - System call. This was modified, in order to use and guarantee coincidental storage addresses at the same time that two ranges did not lie next to each other. Additionally the reservation was coincidentally arranged by small blocks within common ranges. The free function was changed, in order to return memory immediately to the Kernel, instead of leaving it shown during the process. A multiplicity of further optional examinations was added. These abilities simplify a finding of program errors and make their utilization more difficult: In place of memory falsifications or ignoring of unauthorized accesses error often causes a protection injury (SIGSEGV) - and thus the completion of the process. This brought some problems in OpenBSD to 3,8 to the light, which would have been ignored before. Particularly programs, which read beyond the beginning or the end of a buffer, cause now errors. This without considerable speed losses to make possible needed more than three years for the completion. Similar goals are pursued as those the Electric Fence malloc library for the error clearing of Bruce Perens.

Kryptografie and randomization

One of the goals of the OpenBSD project is it, as much kryptografische software and functions as integrating possible into the operating system. For this purpose a quantity of systemnear abilities is made available: A strong pseudo-random number generator, integrated kryptografische Hash functions and - transformations and support for kryptografische hardware accelerators. These abilities find strong use on many levels: One is the password hash algorithm derived from Bruce Schneiers Blowfish Blockchiffre. This draws its advantage from the slow Blowfish why password inquiries are more difficult very CCU lastig and thus attempts to crack the password by Bruteforce (because more slowly). The network minutes pile makes strong use of randomization, in order to reduce the predictableness of some values interesting for aggressors and to increase thus security. This contains the ISN and time stamp fields as well as the haven number volatile source haven in the TCP Protokoll.SecurityFocus. Federico Biancuzzi, OpenBSD's network stack, 12 October 2005. OpenBSD contains also a multiplicity of functions, in order the network robustness and - availability to increase. These are among other things counter measures against problems with ICMP and software for redundancy, for example CARP and pfsync. The project was probably first, which deactivated the plain language telnet Daemon in favor of the coding SSH Daemons and took up other kryptografische software measures - like e.g. IPsec and Kerberos -.

Other functions

Privilege separation, privilege recalling, Chroots and coincidental load from libraries play likewise an increasing role for the system security. Many of it were applied in OpenBSD to usual programs, as tcpdump and the Apache server.

Appendix and indication of source

Articles in category "OpenBSD security characteristics"

We found here 5 articles.

Related Websites

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