mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-27 11:19:37 +00:00
![Daniel Micay](/assets/img/avatar_default.png)
This adds support for compiling with a rough equivalent to the glibc _FORTIFY_SOURCE=1 feature, providing compile-time and runtime buffer overflow checks for string.h functions when the compiler determines the size of the source or destination buffer at compile-time. Unlike glibc, it covers buffer reads in addition to writes. GNU C __builtin_*_chk intrinsics are avoided because they would force a much more complex implementation. They aren't designed to detect read overflows and offer no real benefit when using an implementation based on inline checks. Inline checks don't add up to much code size and allow full use of the regular string intrinsics while avoiding the need for a bunch of _chk functions and per-arch assembly to avoid wrapper overhead. This detects various overflows at compile-time in various drivers and some non-x86 core kernel code. There will likely be issues caught in regular use at runtime too. Future improvements left out of initial implementation for simplicity, as it's all quite optional and can be done incrementally: * Some of the fortified string functions (strncpy, strcat), don't yet place a limit on reads from the source based on __builtin_object_size of the source buffer. * Extending coverage to more string functions like strlcat. * It should be possible to optionally use __builtin_object_size(x, 1) for some functions (C strings) to detect intra-object overflows (like glibc's _FORTIFY_SOURCE=2), but for now this takes the conservative approach to avoid likely compatibility issues. * The compile-time checks should be made available via a separate config option which can be enabled by default (or always enabled) once enough time has passed to get the issues it catches fixed. Kees said: "This is great to have. While it was out-of-tree code, it would have blocked at least CVE-2016-3858 from being exploitable (improper size argument to strlcpy()). I've sent a number of fixes for out-of-bounds-reads that this detected upstream already" [arnd@arndb.de: x86: fix fortified memcpy] Link: http://lkml.kernel.org/r/20170627150047.660360-1-arnd@arndb.de [keescook@chromium.org: avoid panic() in favor of BUG()] Link: http://lkml.kernel.org/r/20170626235122.GA25261@beast [keescook@chromium.org: move from -mm, add ARCH_HAS_FORTIFY_SOURCE, tweak Kconfig help] Link: http://lkml.kernel.org/r/20170526095404.20439-1-danielmicay@gmail.com Link: http://lkml.kernel.org/r/1497903987-21002-8-git-send-email-keescook@chromium.org Signed-off-by: Daniel Micay <danielmicay@gmail.com> Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Kees Cook <keescook@chromium.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Daniel Axtens <dja@axtens.net> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
943 lines
29 KiB
Text
943 lines
29 KiB
Text
#
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# General architecture dependent options
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#
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config CRASH_CORE
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bool
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config KEXEC_CORE
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select CRASH_CORE
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bool
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config HAVE_IMA_KEXEC
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bool
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config OPROFILE
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tristate "OProfile system profiling"
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depends on PROFILING
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depends on HAVE_OPROFILE
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select RING_BUFFER
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select RING_BUFFER_ALLOW_SWAP
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help
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OProfile is a profiling system capable of profiling the
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whole system, include the kernel, kernel modules, libraries,
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and applications.
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If unsure, say N.
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config OPROFILE_EVENT_MULTIPLEX
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bool "OProfile multiplexing support (EXPERIMENTAL)"
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default n
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depends on OPROFILE && X86
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help
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The number of hardware counters is limited. The multiplexing
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feature enables OProfile to gather more events than counters
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are provided by the hardware. This is realized by switching
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between events at a user specified time interval.
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If unsure, say N.
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config HAVE_OPROFILE
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bool
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config OPROFILE_NMI_TIMER
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def_bool y
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depends on PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !PPC64
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config KPROBES
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bool "Kprobes"
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depends on MODULES
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depends on HAVE_KPROBES
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select KALLSYMS
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help
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Kprobes allows you to trap at almost any kernel address and
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execute a callback function. register_kprobe() establishes
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a probepoint and specifies the callback. Kprobes is useful
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for kernel debugging, non-intrusive instrumentation and testing.
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If in doubt, say "N".
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config JUMP_LABEL
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bool "Optimize very unlikely/likely branches"
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depends on HAVE_ARCH_JUMP_LABEL
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help
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This option enables a transparent branch optimization that
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makes certain almost-always-true or almost-always-false branch
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conditions even cheaper to execute within the kernel.
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Certain performance-sensitive kernel code, such as trace points,
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scheduler functionality, networking code and KVM have such
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branches and include support for this optimization technique.
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If it is detected that the compiler has support for "asm goto",
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the kernel will compile such branches with just a nop
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instruction. When the condition flag is toggled to true, the
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nop will be converted to a jump instruction to execute the
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conditional block of instructions.
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This technique lowers overhead and stress on the branch prediction
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of the processor and generally makes the kernel faster. The update
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of the condition is slower, but those are always very rare.
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( On 32-bit x86, the necessary options added to the compiler
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flags may increase the size of the kernel slightly. )
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config STATIC_KEYS_SELFTEST
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bool "Static key selftest"
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depends on JUMP_LABEL
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help
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Boot time self-test of the branch patching code.
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config OPTPROBES
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def_bool y
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depends on KPROBES && HAVE_OPTPROBES
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depends on !PREEMPT
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config KPROBES_ON_FTRACE
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def_bool y
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depends on KPROBES && HAVE_KPROBES_ON_FTRACE
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depends on DYNAMIC_FTRACE_WITH_REGS
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help
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If function tracer is enabled and the arch supports full
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passing of pt_regs to function tracing, then kprobes can
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optimize on top of function tracing.
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config UPROBES
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def_bool n
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depends on ARCH_SUPPORTS_UPROBES
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help
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Uprobes is the user-space counterpart to kprobes: they
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enable instrumentation applications (such as 'perf probe')
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to establish unintrusive probes in user-space binaries and
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libraries, by executing handler functions when the probes
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are hit by user-space applications.
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( These probes come in the form of single-byte breakpoints,
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managed by the kernel and kept transparent to the probed
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application. )
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config HAVE_64BIT_ALIGNED_ACCESS
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def_bool 64BIT && !HAVE_EFFICIENT_UNALIGNED_ACCESS
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help
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Some architectures require 64 bit accesses to be 64 bit
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aligned, which also requires structs containing 64 bit values
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to be 64 bit aligned too. This includes some 32 bit
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architectures which can do 64 bit accesses, as well as 64 bit
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architectures without unaligned access.
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This symbol should be selected by an architecture if 64 bit
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accesses are required to be 64 bit aligned in this way even
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though it is not a 64 bit architecture.
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See Documentation/unaligned-memory-access.txt for more
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information on the topic of unaligned memory accesses.
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config HAVE_EFFICIENT_UNALIGNED_ACCESS
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bool
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help
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Some architectures are unable to perform unaligned accesses
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without the use of get_unaligned/put_unaligned. Others are
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unable to perform such accesses efficiently (e.g. trap on
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unaligned access and require fixing it up in the exception
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handler.)
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This symbol should be selected by an architecture if it can
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perform unaligned accesses efficiently to allow different
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code paths to be selected for these cases. Some network
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drivers, for example, could opt to not fix up alignment
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problems with received packets if doing so would not help
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much.
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See Documentation/unaligned-memory-access.txt for more
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information on the topic of unaligned memory accesses.
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config ARCH_USE_BUILTIN_BSWAP
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bool
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help
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Modern versions of GCC (since 4.4) have builtin functions
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for handling byte-swapping. Using these, instead of the old
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inline assembler that the architecture code provides in the
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__arch_bswapXX() macros, allows the compiler to see what's
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happening and offers more opportunity for optimisation. In
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particular, the compiler will be able to combine the byteswap
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with a nearby load or store and use load-and-swap or
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store-and-swap instructions if the architecture has them. It
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should almost *never* result in code which is worse than the
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hand-coded assembler in <asm/swab.h>. But just in case it
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does, the use of the builtins is optional.
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Any architecture with load-and-swap or store-and-swap
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instructions should set this. And it shouldn't hurt to set it
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on architectures that don't have such instructions.
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config KRETPROBES
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def_bool y
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depends on KPROBES && HAVE_KRETPROBES
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config USER_RETURN_NOTIFIER
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bool
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depends on HAVE_USER_RETURN_NOTIFIER
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help
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Provide a kernel-internal notification when a cpu is about to
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switch to user mode.
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config HAVE_IOREMAP_PROT
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bool
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config HAVE_KPROBES
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bool
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config HAVE_KRETPROBES
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bool
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config HAVE_OPTPROBES
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bool
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config HAVE_KPROBES_ON_FTRACE
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bool
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config HAVE_NMI
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bool
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#
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# An arch should select this if it provides all these things:
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#
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# task_pt_regs() in asm/processor.h or asm/ptrace.h
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# arch_has_single_step() if there is hardware single-step support
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# arch_has_block_step() if there is hardware block-step support
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# asm/syscall.h supplying asm-generic/syscall.h interface
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# linux/regset.h user_regset interfaces
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# CORE_DUMP_USE_REGSET #define'd in linux/elf.h
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# TIF_SYSCALL_TRACE calls tracehook_report_syscall_{entry,exit}
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# TIF_NOTIFY_RESUME calls tracehook_notify_resume()
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# signal delivery calls tracehook_signal_handler()
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#
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config HAVE_ARCH_TRACEHOOK
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bool
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config HAVE_DMA_CONTIGUOUS
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bool
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config GENERIC_SMP_IDLE_THREAD
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bool
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config GENERIC_IDLE_POLL_SETUP
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bool
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config ARCH_HAS_FORTIFY_SOURCE
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bool
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help
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An architecture should select this when it can successfully
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build and run with CONFIG_FORTIFY_SOURCE.
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# Select if arch has all set_memory_ro/rw/x/nx() functions in asm/cacheflush.h
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config ARCH_HAS_SET_MEMORY
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bool
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# Select if arch init_task initializer is different to init/init_task.c
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config ARCH_INIT_TASK
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bool
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# Select if arch has its private alloc_task_struct() function
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config ARCH_TASK_STRUCT_ALLOCATOR
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bool
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# Select if arch has its private alloc_thread_stack() function
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config ARCH_THREAD_STACK_ALLOCATOR
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bool
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# Select if arch wants to size task_struct dynamically via arch_task_struct_size:
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config ARCH_WANTS_DYNAMIC_TASK_STRUCT
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bool
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config HAVE_REGS_AND_STACK_ACCESS_API
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bool
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help
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This symbol should be selected by an architecure if it supports
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the API needed to access registers and stack entries from pt_regs,
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declared in asm/ptrace.h
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For example the kprobes-based event tracer needs this API.
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config HAVE_CLK
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bool
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help
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The <linux/clk.h> calls support software clock gating and
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thus are a key power management tool on many systems.
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config HAVE_DMA_API_DEBUG
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bool
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config HAVE_HW_BREAKPOINT
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bool
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depends on PERF_EVENTS
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config HAVE_MIXED_BREAKPOINTS_REGS
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bool
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depends on HAVE_HW_BREAKPOINT
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help
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Depending on the arch implementation of hardware breakpoints,
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some of them have separate registers for data and instruction
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breakpoints addresses, others have mixed registers to store
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them but define the access type in a control register.
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Select this option if your arch implements breakpoints under the
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latter fashion.
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config HAVE_USER_RETURN_NOTIFIER
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bool
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config HAVE_PERF_EVENTS_NMI
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bool
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help
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System hardware can generate an NMI using the perf event
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subsystem. Also has support for calculating CPU cycle events
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to determine how many clock cycles in a given period.
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config HAVE_HARDLOCKUP_DETECTOR_PERF
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bool
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depends on HAVE_PERF_EVENTS_NMI
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help
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The arch chooses to use the generic perf-NMI-based hardlockup
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detector. Must define HAVE_PERF_EVENTS_NMI.
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config HAVE_NMI_WATCHDOG
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depends on HAVE_NMI
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bool
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help
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The arch provides a low level NMI watchdog. It provides
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asm/nmi.h, and defines its own arch_touch_nmi_watchdog().
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config HAVE_HARDLOCKUP_DETECTOR_ARCH
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bool
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select HAVE_NMI_WATCHDOG
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help
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The arch chooses to provide its own hardlockup detector, which is
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a superset of the HAVE_NMI_WATCHDOG. It also conforms to config
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interfaces and parameters provided by hardlockup detector subsystem.
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config HAVE_PERF_REGS
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bool
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help
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Support selective register dumps for perf events. This includes
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bit-mapping of each registers and a unique architecture id.
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config HAVE_PERF_USER_STACK_DUMP
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bool
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help
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Support user stack dumps for perf event samples. This needs
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access to the user stack pointer which is not unified across
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architectures.
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config HAVE_ARCH_JUMP_LABEL
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bool
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config HAVE_RCU_TABLE_FREE
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bool
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config ARCH_HAVE_NMI_SAFE_CMPXCHG
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bool
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config HAVE_ALIGNED_STRUCT_PAGE
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bool
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help
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This makes sure that struct pages are double word aligned and that
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e.g. the SLUB allocator can perform double word atomic operations
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on a struct page for better performance. However selecting this
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might increase the size of a struct page by a word.
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config HAVE_CMPXCHG_LOCAL
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bool
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config HAVE_CMPXCHG_DOUBLE
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bool
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config ARCH_WEAK_RELEASE_ACQUIRE
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bool
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config ARCH_WANT_IPC_PARSE_VERSION
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bool
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config ARCH_WANT_COMPAT_IPC_PARSE_VERSION
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bool
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config ARCH_WANT_OLD_COMPAT_IPC
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select ARCH_WANT_COMPAT_IPC_PARSE_VERSION
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bool
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config HAVE_ARCH_SECCOMP_FILTER
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bool
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help
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An arch should select this symbol if it provides all of these things:
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- syscall_get_arch()
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- syscall_get_arguments()
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- syscall_rollback()
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- syscall_set_return_value()
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- SIGSYS siginfo_t support
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- secure_computing is called from a ptrace_event()-safe context
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- secure_computing return value is checked and a return value of -1
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results in the system call being skipped immediately.
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- seccomp syscall wired up
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config SECCOMP_FILTER
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def_bool y
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depends on HAVE_ARCH_SECCOMP_FILTER && SECCOMP && NET
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help
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Enable tasks to build secure computing environments defined
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in terms of Berkeley Packet Filter programs which implement
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task-defined system call filtering polices.
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See Documentation/prctl/seccomp_filter.txt for details.
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config HAVE_GCC_PLUGINS
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bool
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help
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An arch should select this symbol if it supports building with
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GCC plugins.
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menuconfig GCC_PLUGINS
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bool "GCC plugins"
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depends on HAVE_GCC_PLUGINS
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depends on !COMPILE_TEST
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help
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GCC plugins are loadable modules that provide extra features to the
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compiler. They are useful for runtime instrumentation and static analysis.
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See Documentation/gcc-plugins.txt for details.
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config GCC_PLUGIN_CYC_COMPLEXITY
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bool "Compute the cyclomatic complexity of a function" if EXPERT
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depends on GCC_PLUGINS
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depends on !COMPILE_TEST
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help
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The complexity M of a function's control flow graph is defined as:
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M = E - N + 2P
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where
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E = the number of edges
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N = the number of nodes
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P = the number of connected components (exit nodes).
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Enabling this plugin reports the complexity to stderr during the
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build. It mainly serves as a simple example of how to create a
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gcc plugin for the kernel.
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config GCC_PLUGIN_SANCOV
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bool
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depends on GCC_PLUGINS
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help
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This plugin inserts a __sanitizer_cov_trace_pc() call at the start of
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basic blocks. It supports all gcc versions with plugin support (from
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gcc-4.5 on). It is based on the commit "Add fuzzing coverage support"
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by Dmitry Vyukov <dvyukov@google.com>.
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config GCC_PLUGIN_LATENT_ENTROPY
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bool "Generate some entropy during boot and runtime"
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depends on GCC_PLUGINS
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help
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By saying Y here the kernel will instrument some kernel code to
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extract some entropy from both original and artificially created
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program state. This will help especially embedded systems where
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there is little 'natural' source of entropy normally. The cost
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is some slowdown of the boot process (about 0.5%) and fork and
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irq processing.
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Note that entropy extracted this way is not cryptographically
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secure!
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This plugin was ported from grsecurity/PaX. More information at:
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* https://grsecurity.net/
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* https://pax.grsecurity.net/
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config GCC_PLUGIN_STRUCTLEAK
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bool "Force initialization of variables containing userspace addresses"
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depends on GCC_PLUGINS
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help
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This plugin zero-initializes any structures containing a
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__user attribute. This can prevent some classes of information
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exposures.
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This plugin was ported from grsecurity/PaX. More information at:
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* https://grsecurity.net/
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* https://pax.grsecurity.net/
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config GCC_PLUGIN_STRUCTLEAK_VERBOSE
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bool "Report forcefully initialized variables"
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depends on GCC_PLUGIN_STRUCTLEAK
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depends on !COMPILE_TEST
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help
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This option will cause a warning to be printed each time the
|
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structleak plugin finds a variable it thinks needs to be
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initialized. Since not all existing initializers are detected
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by the plugin, this can produce false positive warnings.
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config GCC_PLUGIN_RANDSTRUCT
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bool "Randomize layout of sensitive kernel structures"
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depends on GCC_PLUGINS
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select MODVERSIONS if MODULES
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help
|
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If you say Y here, the layouts of structures explicitly
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marked by __randomize_layout will be randomized at
|
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compile-time. This can introduce the requirement of an
|
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additional information exposure vulnerability for exploits
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targeting these structure types.
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|
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Enabling this feature will introduce some performance impact,
|
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slightly increase memory usage, and prevent the use of forensic
|
|
tools like Volatility against the system (unless the kernel
|
|
source tree isn't cleaned after kernel installation).
|
|
|
|
The seed used for compilation is located at
|
|
scripts/gcc-plgins/randomize_layout_seed.h. It remains after
|
|
a make clean to allow for external modules to be compiled with
|
|
the existing seed and will be removed by a make mrproper or
|
|
make distclean.
|
|
|
|
Note that the implementation requires gcc 4.7 or newer.
|
|
|
|
This plugin was ported from grsecurity/PaX. More information at:
|
|
* https://grsecurity.net/
|
|
* https://pax.grsecurity.net/
|
|
|
|
config GCC_PLUGIN_RANDSTRUCT_PERFORMANCE
|
|
bool "Use cacheline-aware structure randomization"
|
|
depends on GCC_PLUGIN_RANDSTRUCT
|
|
depends on !COMPILE_TEST
|
|
help
|
|
If you say Y here, the RANDSTRUCT randomization will make a
|
|
best effort at restricting randomization to cacheline-sized
|
|
groups of elements. It will further not randomize bitfields
|
|
in structures. This reduces the performance hit of RANDSTRUCT
|
|
at the cost of weakened randomization.
|
|
|
|
config HAVE_CC_STACKPROTECTOR
|
|
bool
|
|
help
|
|
An arch should select this symbol if:
|
|
- its compiler supports the -fstack-protector option
|
|
- it has implemented a stack canary (e.g. __stack_chk_guard)
|
|
|
|
config CC_STACKPROTECTOR
|
|
def_bool n
|
|
help
|
|
Set when a stack-protector mode is enabled, so that the build
|
|
can enable kernel-side support for the GCC feature.
|
|
|
|
choice
|
|
prompt "Stack Protector buffer overflow detection"
|
|
depends on HAVE_CC_STACKPROTECTOR
|
|
default CC_STACKPROTECTOR_NONE
|
|
help
|
|
This option turns on the "stack-protector" GCC feature. This
|
|
feature puts, at the beginning of functions, a canary value on
|
|
the stack just before the return address, and validates
|
|
the value just before actually returning. Stack based buffer
|
|
overflows (that need to overwrite this return address) now also
|
|
overwrite the canary, which gets detected and the attack is then
|
|
neutralized via a kernel panic.
|
|
|
|
config CC_STACKPROTECTOR_NONE
|
|
bool "None"
|
|
help
|
|
Disable "stack-protector" GCC feature.
|
|
|
|
config CC_STACKPROTECTOR_REGULAR
|
|
bool "Regular"
|
|
select CC_STACKPROTECTOR
|
|
help
|
|
Functions will have the stack-protector canary logic added if they
|
|
have an 8-byte or larger character array on the stack.
|
|
|
|
This feature requires gcc version 4.2 or above, or a distribution
|
|
gcc with the feature backported ("-fstack-protector").
|
|
|
|
On an x86 "defconfig" build, this feature adds canary checks to
|
|
about 3% of all kernel functions, which increases kernel code size
|
|
by about 0.3%.
|
|
|
|
config CC_STACKPROTECTOR_STRONG
|
|
bool "Strong"
|
|
select CC_STACKPROTECTOR
|
|
help
|
|
Functions will have the stack-protector canary logic added in any
|
|
of the following conditions:
|
|
|
|
- local variable's address used as part of the right hand side of an
|
|
assignment or function argument
|
|
- local variable is an array (or union containing an array),
|
|
regardless of array type or length
|
|
- uses register local variables
|
|
|
|
This feature requires gcc version 4.9 or above, or a distribution
|
|
gcc with the feature backported ("-fstack-protector-strong").
|
|
|
|
On an x86 "defconfig" build, this feature adds canary checks to
|
|
about 20% of all kernel functions, which increases the kernel code
|
|
size by about 2%.
|
|
|
|
endchoice
|
|
|
|
config THIN_ARCHIVES
|
|
def_bool y
|
|
help
|
|
Select this if the architecture wants to use thin archives
|
|
instead of ld -r to create the built-in.o files.
|
|
|
|
config LD_DEAD_CODE_DATA_ELIMINATION
|
|
bool
|
|
help
|
|
Select this if the architecture wants to do dead code and
|
|
data elimination with the linker by compiling with
|
|
-ffunction-sections -fdata-sections and linking with
|
|
--gc-sections.
|
|
|
|
This requires that the arch annotates or otherwise protects
|
|
its external entry points from being discarded. Linker scripts
|
|
must also merge .text.*, .data.*, and .bss.* correctly into
|
|
output sections. Care must be taken not to pull in unrelated
|
|
sections (e.g., '.text.init'). Typically '.' in section names
|
|
is used to distinguish them from label names / C identifiers.
|
|
|
|
config HAVE_ARCH_WITHIN_STACK_FRAMES
|
|
bool
|
|
help
|
|
An architecture should select this if it can walk the kernel stack
|
|
frames to determine if an object is part of either the arguments
|
|
or local variables (i.e. that it excludes saved return addresses,
|
|
and similar) by implementing an inline arch_within_stack_frames(),
|
|
which is used by CONFIG_HARDENED_USERCOPY.
|
|
|
|
config HAVE_CONTEXT_TRACKING
|
|
bool
|
|
help
|
|
Provide kernel/user boundaries probes necessary for subsystems
|
|
that need it, such as userspace RCU extended quiescent state.
|
|
Syscalls need to be wrapped inside user_exit()-user_enter() through
|
|
the slow path using TIF_NOHZ flag. Exceptions handlers must be
|
|
wrapped as well. Irqs are already protected inside
|
|
rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on
|
|
irq exit still need to be protected.
|
|
|
|
config HAVE_VIRT_CPU_ACCOUNTING
|
|
bool
|
|
|
|
config ARCH_HAS_SCALED_CPUTIME
|
|
bool
|
|
|
|
config HAVE_VIRT_CPU_ACCOUNTING_GEN
|
|
bool
|
|
default y if 64BIT
|
|
help
|
|
With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit.
|
|
Before enabling this option, arch code must be audited
|
|
to ensure there are no races in concurrent read/write of
|
|
cputime_t. For example, reading/writing 64-bit cputime_t on
|
|
some 32-bit arches may require multiple accesses, so proper
|
|
locking is needed to protect against concurrent accesses.
|
|
|
|
|
|
config HAVE_IRQ_TIME_ACCOUNTING
|
|
bool
|
|
help
|
|
Archs need to ensure they use a high enough resolution clock to
|
|
support irq time accounting and then call enable_sched_clock_irqtime().
|
|
|
|
config HAVE_ARCH_TRANSPARENT_HUGEPAGE
|
|
bool
|
|
|
|
config HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
|
|
bool
|
|
|
|
config HAVE_ARCH_HUGE_VMAP
|
|
bool
|
|
|
|
config HAVE_ARCH_SOFT_DIRTY
|
|
bool
|
|
|
|
config HAVE_MOD_ARCH_SPECIFIC
|
|
bool
|
|
help
|
|
The arch uses struct mod_arch_specific to store data. Many arches
|
|
just need a simple module loader without arch specific data - those
|
|
should not enable this.
|
|
|
|
config MODULES_USE_ELF_RELA
|
|
bool
|
|
help
|
|
Modules only use ELF RELA relocations. Modules with ELF REL
|
|
relocations will give an error.
|
|
|
|
config MODULES_USE_ELF_REL
|
|
bool
|
|
help
|
|
Modules only use ELF REL relocations. Modules with ELF RELA
|
|
relocations will give an error.
|
|
|
|
config HAVE_UNDERSCORE_SYMBOL_PREFIX
|
|
bool
|
|
help
|
|
Some architectures generate an _ in front of C symbols; things like
|
|
module loading and assembly files need to know about this.
|
|
|
|
config HAVE_IRQ_EXIT_ON_IRQ_STACK
|
|
bool
|
|
help
|
|
Architecture doesn't only execute the irq handler on the irq stack
|
|
but also irq_exit(). This way we can process softirqs on this irq
|
|
stack instead of switching to a new one when we call __do_softirq()
|
|
in the end of an hardirq.
|
|
This spares a stack switch and improves cache usage on softirq
|
|
processing.
|
|
|
|
config PGTABLE_LEVELS
|
|
int
|
|
default 2
|
|
|
|
config ARCH_HAS_ELF_RANDOMIZE
|
|
bool
|
|
help
|
|
An architecture supports choosing randomized locations for
|
|
stack, mmap, brk, and ET_DYN. Defined functions:
|
|
- arch_mmap_rnd()
|
|
- arch_randomize_brk()
|
|
|
|
config HAVE_ARCH_MMAP_RND_BITS
|
|
bool
|
|
help
|
|
An arch should select this symbol if it supports setting a variable
|
|
number of bits for use in establishing the base address for mmap
|
|
allocations, has MMU enabled and provides values for both:
|
|
- ARCH_MMAP_RND_BITS_MIN
|
|
- ARCH_MMAP_RND_BITS_MAX
|
|
|
|
config HAVE_EXIT_THREAD
|
|
bool
|
|
help
|
|
An architecture implements exit_thread.
|
|
|
|
config ARCH_MMAP_RND_BITS_MIN
|
|
int
|
|
|
|
config ARCH_MMAP_RND_BITS_MAX
|
|
int
|
|
|
|
config ARCH_MMAP_RND_BITS_DEFAULT
|
|
int
|
|
|
|
config ARCH_MMAP_RND_BITS
|
|
int "Number of bits to use for ASLR of mmap base address" if EXPERT
|
|
range ARCH_MMAP_RND_BITS_MIN ARCH_MMAP_RND_BITS_MAX
|
|
default ARCH_MMAP_RND_BITS_DEFAULT if ARCH_MMAP_RND_BITS_DEFAULT
|
|
default ARCH_MMAP_RND_BITS_MIN
|
|
depends on HAVE_ARCH_MMAP_RND_BITS
|
|
help
|
|
This value can be used to select the number of bits to use to
|
|
determine the random offset to the base address of vma regions
|
|
resulting from mmap allocations. This value will be bounded
|
|
by the architecture's minimum and maximum supported values.
|
|
|
|
This value can be changed after boot using the
|
|
/proc/sys/vm/mmap_rnd_bits tunable
|
|
|
|
config HAVE_ARCH_MMAP_RND_COMPAT_BITS
|
|
bool
|
|
help
|
|
An arch should select this symbol if it supports running applications
|
|
in compatibility mode, supports setting a variable number of bits for
|
|
use in establishing the base address for mmap allocations, has MMU
|
|
enabled and provides values for both:
|
|
- ARCH_MMAP_RND_COMPAT_BITS_MIN
|
|
- ARCH_MMAP_RND_COMPAT_BITS_MAX
|
|
|
|
config ARCH_MMAP_RND_COMPAT_BITS_MIN
|
|
int
|
|
|
|
config ARCH_MMAP_RND_COMPAT_BITS_MAX
|
|
int
|
|
|
|
config ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
|
|
int
|
|
|
|
config ARCH_MMAP_RND_COMPAT_BITS
|
|
int "Number of bits to use for ASLR of mmap base address for compatible applications" if EXPERT
|
|
range ARCH_MMAP_RND_COMPAT_BITS_MIN ARCH_MMAP_RND_COMPAT_BITS_MAX
|
|
default ARCH_MMAP_RND_COMPAT_BITS_DEFAULT if ARCH_MMAP_RND_COMPAT_BITS_DEFAULT
|
|
default ARCH_MMAP_RND_COMPAT_BITS_MIN
|
|
depends on HAVE_ARCH_MMAP_RND_COMPAT_BITS
|
|
help
|
|
This value can be used to select the number of bits to use to
|
|
determine the random offset to the base address of vma regions
|
|
resulting from mmap allocations for compatible applications This
|
|
value will be bounded by the architecture's minimum and maximum
|
|
supported values.
|
|
|
|
This value can be changed after boot using the
|
|
/proc/sys/vm/mmap_rnd_compat_bits tunable
|
|
|
|
config HAVE_ARCH_COMPAT_MMAP_BASES
|
|
bool
|
|
help
|
|
This allows 64bit applications to invoke 32-bit mmap() syscall
|
|
and vice-versa 32-bit applications to call 64-bit mmap().
|
|
Required for applications doing different bitness syscalls.
|
|
|
|
config HAVE_COPY_THREAD_TLS
|
|
bool
|
|
help
|
|
Architecture provides copy_thread_tls to accept tls argument via
|
|
normal C parameter passing, rather than extracting the syscall
|
|
argument from pt_regs.
|
|
|
|
config HAVE_STACK_VALIDATION
|
|
bool
|
|
help
|
|
Architecture supports the 'objtool check' host tool command, which
|
|
performs compile-time stack metadata validation.
|
|
|
|
config HAVE_RELIABLE_STACKTRACE
|
|
bool
|
|
help
|
|
Architecture has a save_stack_trace_tsk_reliable() function which
|
|
only returns a stack trace if it can guarantee the trace is reliable.
|
|
|
|
config HAVE_ARCH_HASH
|
|
bool
|
|
default n
|
|
help
|
|
If this is set, the architecture provides an <asm/hash.h>
|
|
file which provides platform-specific implementations of some
|
|
functions in <linux/hash.h> or fs/namei.c.
|
|
|
|
config ISA_BUS_API
|
|
def_bool ISA
|
|
|
|
#
|
|
# ABI hall of shame
|
|
#
|
|
config CLONE_BACKWARDS
|
|
bool
|
|
help
|
|
Architecture has tls passed as the 4th argument of clone(2),
|
|
not the 5th one.
|
|
|
|
config CLONE_BACKWARDS2
|
|
bool
|
|
help
|
|
Architecture has the first two arguments of clone(2) swapped.
|
|
|
|
config CLONE_BACKWARDS3
|
|
bool
|
|
help
|
|
Architecture has tls passed as the 3rd argument of clone(2),
|
|
not the 5th one.
|
|
|
|
config ODD_RT_SIGACTION
|
|
bool
|
|
help
|
|
Architecture has unusual rt_sigaction(2) arguments
|
|
|
|
config OLD_SIGSUSPEND
|
|
bool
|
|
help
|
|
Architecture has old sigsuspend(2) syscall, of one-argument variety
|
|
|
|
config OLD_SIGSUSPEND3
|
|
bool
|
|
help
|
|
Even weirder antique ABI - three-argument sigsuspend(2)
|
|
|
|
config OLD_SIGACTION
|
|
bool
|
|
help
|
|
Architecture has old sigaction(2) syscall. Nope, not the same
|
|
as OLD_SIGSUSPEND | OLD_SIGSUSPEND3 - alpha has sigsuspend(2),
|
|
but fairly different variant of sigaction(2), thanks to OSF/1
|
|
compatibility...
|
|
|
|
config COMPAT_OLD_SIGACTION
|
|
bool
|
|
|
|
config ARCH_NO_COHERENT_DMA_MMAP
|
|
bool
|
|
|
|
config CPU_NO_EFFICIENT_FFS
|
|
def_bool n
|
|
|
|
config HAVE_ARCH_VMAP_STACK
|
|
def_bool n
|
|
help
|
|
An arch should select this symbol if it can support kernel stacks
|
|
in vmalloc space. This means:
|
|
|
|
- vmalloc space must be large enough to hold many kernel stacks.
|
|
This may rule out many 32-bit architectures.
|
|
|
|
- Stacks in vmalloc space need to work reliably. For example, if
|
|
vmap page tables are created on demand, either this mechanism
|
|
needs to work while the stack points to a virtual address with
|
|
unpopulated page tables or arch code (switch_to() and switch_mm(),
|
|
most likely) needs to ensure that the stack's page table entries
|
|
are populated before running on a possibly unpopulated stack.
|
|
|
|
- If the stack overflows into a guard page, something reasonable
|
|
should happen. The definition of "reasonable" is flexible, but
|
|
instantly rebooting without logging anything would be unfriendly.
|
|
|
|
config VMAP_STACK
|
|
default y
|
|
bool "Use a virtually-mapped stack"
|
|
depends on HAVE_ARCH_VMAP_STACK && !KASAN
|
|
---help---
|
|
Enable this if you want the use virtually-mapped kernel stacks
|
|
with guard pages. This causes kernel stack overflows to be
|
|
caught immediately rather than causing difficult-to-diagnose
|
|
corruption.
|
|
|
|
This is presently incompatible with KASAN because KASAN expects
|
|
the stack to map directly to the KASAN shadow map using a formula
|
|
that is incorrect if the stack is in vmalloc space.
|
|
|
|
config ARCH_OPTIONAL_KERNEL_RWX
|
|
def_bool n
|
|
|
|
config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
|
|
def_bool n
|
|
|
|
config ARCH_HAS_STRICT_KERNEL_RWX
|
|
def_bool n
|
|
|
|
config STRICT_KERNEL_RWX
|
|
bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
|
|
depends on ARCH_HAS_STRICT_KERNEL_RWX
|
|
default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
|
|
help
|
|
If this is set, kernel text and rodata memory will be made read-only,
|
|
and non-text memory will be made non-executable. This provides
|
|
protection against certain security exploits (e.g. executing the heap
|
|
or modifying text)
|
|
|
|
These features are considered standard security practice these days.
|
|
You should say Y here in almost all cases.
|
|
|
|
config ARCH_HAS_STRICT_MODULE_RWX
|
|
def_bool n
|
|
|
|
config STRICT_MODULE_RWX
|
|
bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX
|
|
depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
|
|
default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
|
|
help
|
|
If this is set, module text and rodata memory will be made read-only,
|
|
and non-text memory will be made non-executable. This provides
|
|
protection against certain security exploits (e.g. writing to text)
|
|
|
|
config ARCH_WANT_RELAX_ORDER
|
|
bool
|
|
|
|
config REFCOUNT_FULL
|
|
bool "Perform full reference count validation at the expense of speed"
|
|
help
|
|
Enabling this switches the refcounting infrastructure from a fast
|
|
unchecked atomic_t implementation to a fully state checked
|
|
implementation, which can be (slightly) slower but provides protections
|
|
against various use-after-free conditions that can be used in
|
|
security flaw exploits.
|
|
|
|
source "kernel/gcov/Kconfig"
|