aboutsummaryrefslogtreecommitdiffstats
path: root/arch/x86/boot/compressed/aslr.c
Commit message (Collapse)AuthorAge
* x86, kaslr: Remove unused including <linux/version.h>Wei Yongjun2014-01-14
| | | | | | | | | Remove including <linux/version.h> that don't need it. Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn> Link: http://lkml.kernel.org/r/CAPgLHd-Fjx1RybjWFAu1vHRfTvhWwMLL3x46BouC5uNxHPjy1A@mail.gmail.com Acked-by: Kees Cook <keescook@chromium.org> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
* x86, kaslr: Use char array to gain sizeof sanityKees Cook2013-11-12
| | | | | | | | | | The build_str needs to be char [] not char * for the sizeof() to report the string length. Reported-by: Mathias Krause <minipli@googlemail.com> Signed-off-by: Kees Cook <keescook@chromium.org> Link: http://lkml.kernel.org/r/20131112165607.GA5921@www.outflux.net Signed-off-by: H. Peter Anvin <hpa@zytor.com>
* x86, kaslr: Add a circular multiply for better bit diffusionH. Peter Anvin2013-11-12
| | | | | | | | | | | | | If we don't have RDRAND (in which case nothing else *should* matter), most sources have a highly biased entropy distribution. Use a circular multiply to diffuse the entropic bits. A circular multiply is a good operation for this: it is cheap on standard hardware and because it is symmetric (unlike an ordinary multiply) it doesn't introduce its own bias. Cc: Kees Cook <keescook@chromium.org> Signed-off-by: H. Peter Anvin <hpa@zytor.com> Link: http://lkml.kernel.org/r/20131111222839.GA28616@www.outflux.net
* x86, kaslr: Mix entropy sources together as neededKees Cook2013-11-12
| | | | | | | | | | | | | | | | | Depending on availability, mix the RDRAND and RDTSC entropy together with XOR. Only when neither is available should the i8254 be used. Update the Kconfig documentation to reflect this. Additionally, since bits used for entropy is masked elsewhere, drop the needless masking in the get_random_long(). Similarly, use the entire TSC, not just the low 32 bits. Finally, to improve the starting entropy, do a simple hashing of a build-time versions string and the boot-time boot_params structure for some additional level of unpredictability. Signed-off-by: Kees Cook <keescook@chromium.org> Link: http://lkml.kernel.org/r/20131111222839.GA28616@www.outflux.net Signed-off-by: H. Peter Anvin <hpa@zytor.com>
* x86, kaslr: Select random position from e820 mapsKees Cook2013-10-13
| | | | | | | | | | Counts available alignment positions across all e820 maps, and chooses one randomly for the new kernel base address, making sure not to collide with unsafe memory areas. Signed-off-by: Kees Cook <keescook@chromium.org> Link: http://lkml.kernel.org/r/1381450698-28710-5-git-send-email-keescook@chromium.org Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
* x86, kaslr: Provide randomness functionsKees Cook2013-10-13
| | | | | | | | | | | | Adds potential sources of randomness: RDRAND, RDTSC, or the i8254. This moves the pre-alternatives inline rdrand function into the header so both pieces of code can use it. Availability of RDRAND is then controlled by CONFIG_ARCH_RANDOM, if someone wants to disable it even for kASLR. Signed-off-by: Kees Cook <keescook@chromium.org> Link: http://lkml.kernel.org/r/1381450698-28710-4-git-send-email-keescook@chromium.org Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
* x86, kaslr: Return location from decompress_kernelKees Cook2013-10-13
This allows decompress_kernel to return a new location for the kernel to be relocated to. Additionally, enforces CONFIG_PHYSICAL_START as the minimum relocation position when building with CONFIG_RELOCATABLE. With CONFIG_RANDOMIZE_BASE set, the choose_kernel_location routine will select a new location to decompress the kernel, though here it is presently a no-op. The kernel command line option "nokaslr" is introduced to bypass these routines. Signed-off-by: Kees Cook <keescook@chromium.org> Link: http://lkml.kernel.org/r/1381450698-28710-3-git-send-email-keescook@chromium.org Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>