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Commit:
e2b32e678513 ("x86, kaslr: randomize module base load address")
made module base address randomization unconditional and didn't regard
disabled KKASLR due to CONFIG_HIBERNATION and command line option
"nokaslr". For more info see (now reverted) commit:
f47233c2d34f ("x86/mm/ASLR: Propagate base load address calculation")
In order to propagate KASLR status to kernel proper, we need a single bit
in boot_params.hdr.loadflags and we've chosen bit 1 thus leaving the
top-down allocated bits for bits supposed to be used by the bootloader.
Originally-From: Jiri Kosina <jkosina@suse.cz>
Suggested-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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This reverts commit:
f47233c2d34f ("x86/mm/ASLR: Propagate base load address calculation")
The main reason for the revert is that the new boot flag does not work
at all currently, and in order to make this work, we need non-trivial
changes to the x86 boot code which we didn't manage to get done in
time for merging.
And even if we did, they would've been too risky so instead of
rushing things and break booting 4.1 on boxes left and right, we
will be very strict and conservative and will take our time with
this to fix and test it properly.
Reported-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: H. Peter Anvin <hpa@linux.intel.com
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Junjie Mao <eternal.n08@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt.fleming@intel.com>
Link: http://lkml.kernel.org/r/20150316100628.GD22995@pd.tnic
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Commit:
e2b32e678513 ("x86, kaslr: randomize module base load address")
makes the base address for module to be unconditionally randomized in
case when CONFIG_RANDOMIZE_BASE is defined and "nokaslr" option isn't
present on the commandline.
This is not consistent with how choose_kernel_location() decides whether
it will randomize kernel load base.
Namely, CONFIG_HIBERNATION disables kASLR (unless "kaslr" option is
explicitly specified on kernel commandline), which makes the state space
larger than what module loader is looking at. IOW CONFIG_HIBERNATION &&
CONFIG_RANDOMIZE_BASE is a valid config option, kASLR wouldn't be applied
by default in that case, but module loader is not aware of that.
Instead of fixing the logic in module.c, this patch takes more generic
aproach. It introduces a new bootparam setup data_type SETUP_KASLR and
uses that to pass the information whether kaslr has been applied during
kernel decompression, and sets a global 'kaslr_enabled' variable
accordingly, so that any kernel code (module loading, livepatching, ...)
can make decisions based on its value.
x86 module loader is converted to make use of this flag.
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: "H. Peter Anvin" <hpa@linux.intel.com>
Link: https://lkml.kernel.org/r/alpine.LNX.2.00.1502101411280.10719@pobox.suse.cz
[ Always dump correct kaslr status when panicking ]
Signed-off-by: Borislav Petkov <bp@suse.de>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fixes from Ingo Molnar:
"Misc smaller fixes that missed the v3.17 cycle"
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/build: Add arch/x86/purgatory/ make generated files to gitignore
x86: Fix section conflict for numachip
x86: Reject x32 executables if x32 ABI not supported
x86_64, entry: Filter RFLAGS.NT on entry from userspace
x86, boot, kaslr: Fix nuisance warning on 32-bit builds
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Building 32-bit threw a warning on kASLR enabled builds:
arch/x86/boot/compressed/aslr.c: In function ‘mem_avoid_overlap’:
arch/x86/boot/compressed/aslr.c:198:17: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
avoid.start = (u64)ptr;
^
This fixes the warning; unsigned long should have been used here.
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: http://lkml.kernel.org/r/20141001183632.GA11431@www.outflux.net
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/josh/linux
Pull "tinification" patches from Josh Triplett.
Work on making smaller kernels.
* tag 'tiny/for-3.18' of git://git.kernel.org/pub/scm/linux/kernel/git/josh/linux:
bloat-o-meter: Ignore syscall aliases SyS_ and compat_SyS_
mm: Support compiling out madvise and fadvise
x86: Support compiling out human-friendly processor feature names
x86: Drop support for /proc files when !CONFIG_PROC_FS
x86, boot: Don't compile early_serial_console.c when !CONFIG_EARLY_PRINTK
x86, boot: Don't compile aslr.c when !CONFIG_RANDOMIZE_BASE
x86, boot: Use the usual -y -n mechanism for objects in vmlinux
x86: Add "make tinyconfig" to configure the tiniest possible kernel
x86, platform, kconfig: move kvmconfig functionality to a helper
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All the code in aslr.c gets compiled out if !CONFIG_RANDOMIZE_BASE, but
aslr.o itself still gets compiled in. Eliminate it from the compile
entirely in that case.
This does not change the generated code at all, in either case.
Signed-off-by: Josh Triplett <josh@joshtriplett.org>
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The KASLR location-choosing logic needs to avoid the setup_data
list memory areas as well. Without this, it would be possible to
have the ASLR position stomp on the memory, ultimately causing
the boot to fail.
Signed-off-by: Kees Cook <keescook@chromium.org>
Tested-by: Baoquan He <bhe@redhat.com>
Cc: stable@vger.kernel.org
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140911161931.GA12001@www.outflux.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Changes kASLR from being compile-time selectable (blocked by
CONFIG_HIBERNATION), to being boot-time selectable (with hibernation
available by default) via the "kaslr" kernel command line.
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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This silences build warnings about unexported variables and functions.
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: http://lkml.kernel.org/r/20140209215644.GA30339@www.outflux.net
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
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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>
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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>
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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
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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>
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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>
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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>
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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>
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