There's nothing IST-worthy about #BP/int3. We don't allow kprobes
in the small handful of places in the kernel that run at CPL0 with
an invalid stack, and 32-bit kernels have used normal interrupt
gates for #BP forever.
Furthermore, we don't allow kprobes in places that have usergs while
in kernel mode, so "paranoid" is also unnecessary.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Emanuel reported an issue with a hang during microcode update because my
dumb idea to use one atomic synchronization variable for both rendezvous
- before and after update - was simply bollocks:
microcode: microcode_reload_late: late_cpus: 4
microcode: __reload_late: cpu 2 entered
microcode: __reload_late: cpu 1 entered
microcode: __reload_late: cpu 3 entered
microcode: __reload_late: cpu 0 entered
microcode: __reload_late: cpu 1 left
microcode: Timeout while waiting for CPUs rendezvous, remaining: 1
CPU1 above would finish, leave and the others will still spin waiting for
it to join.
So do two synchronization atomics instead, which makes the code a lot more
straightforward.
Also, since the update is serialized and it also takes quite some time per
microcode engine, increase the exit timeout by the number of CPUs on the
system.
That's ok because the moment all CPUs are done, that timeout will be cut
short.
Furthermore, panic when some of the CPUs timeout when returning from a
microcode update: we can't allow a system with not all cores updated.
Also, as an optimization, do not do the exit sync if microcode wasn't
updated.
Reported-by: Emanuel Czirai <xftroxgpx@protonmail.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Emanuel Czirai <xftroxgpx@protonmail.com>
Tested-by: Ashok Raj <ashok.raj@intel.com>
Tested-by: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://lkml.kernel.org/r/20180314183615.17629-2-bp@alien8.de
The kbuild test robot reported the following warning on sparc64:
kernel/jump_label.c: In function '__jump_label_update':
kernel/jump_label.c:376:51: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
WARN_ONCE(1, "can't patch jump_label at %pS", (void *)entry->code);
On sparc64, the jump_label entry->code field is of type u32, but
pointers are 64-bit. Silence the warning by casting entry->code to an
unsigned long before casting it to a pointer. This is also what the
sparc jump label code does.
Fixes: dc1dd184c2 ("jump_label: Warn on failed jump_label patching attempt")
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: "David S . Miller" <davem@davemloft.net>
Link: https://lkml.kernel.org/r/c966fed42be6611254a62d46579ec7416548d572.1521041026.git.jpoimboe@redhat.com
Disable the kprobe probing of the entry trampoline:
.entry_trampoline is a code area that is used to ensure page table
isolation between userspace and kernelspace.
At the beginning of the execution of the trampoline, we load the
kernel's CR3 register. This has the effect of enabling the translation
of the kernel virtual addresses to physical addresses. Before this
happens most kernel addresses can not be translated because the running
process' CR3 is still used.
If a kprobe is placed on the trampoline code before that change of the
CR3 register happens the kernel crashes because int3 handling pages are
not accessible.
To fix this, add the .entry_trampoline section to the kprobe blacklist
to prohibit the probing of code before all the kernel pages are
accessible.
Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: mathieu.desnoyers@efficios.com
Cc: mhiramat@kernel.org
Link: http://lkml.kernel.org/r/1520565492-4637-2-git-send-email-francis.deslauriers@efficios.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Original idea by Ashok, completely rewritten by Borislav.
Before you read any further: the early loading method is still the
preferred one and you should always do that. The following patch is
improving the late loading mechanism for long running jobs and cloud use
cases.
Gather all cores and serialize the microcode update on them by doing it
one-by-one to make the late update process as reliable as possible and
avoid potential issues caused by the microcode update.
[ Borislav: Rewrite completely. ]
Co-developed-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Tom Lendacky <thomas.lendacky@amd.com>
Tested-by: Ashok Raj <ashok.raj@intel.com>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Arjan Van De Ven <arjan.van.de.ven@intel.com>
Link: https://lkml.kernel.org/r/20180228102846.13447-8-bp@alien8.de
Since Linux v3.2, vsyscalls have been deprecated and slow. From v3.2
on, Linux had three vsyscall modes: "native", "emulate", and "none".
"emulate" is the default. All known user programs work correctly in
emulate mode, but vsyscalls turn into page faults and are emulated.
This is very slow. In "native" mode, the vsyscall page is easily
usable as an exploit gadget, but vsyscalls are a bit faster -- they
turn into normal syscalls. (This is in contrast to vDSO functions,
which can be much faster than syscalls.) In "none" mode, there are
no vsyscalls.
For all practical purposes, "native" was really just a chicken bit
in case something went wrong with the emulation. It's been over six
years, and nothing has gone wrong. Delete it.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Kernel Hardening <kernel-hardening@lists.openwall.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/519fee5268faea09ae550776ce969fa6e88668b0.1520449896.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The separation of the cpu_entry_area from the fixmap missed the fact that
on 32bit non-PAE kernels the cpu_entry_area mapping might not be covered in
initial_page_table by the previous synchronizations.
This results in suspend/resume failures because 32bit utilizes initial page
table for resume. The absence of the cpu_entry_area mapping results in a
triple fault, aka. insta reboot.
With PAE enabled this works by chance because the PGD entry which covers
the fixmap and other parts incindentally provides the cpu_entry_area
mapping as well.
Synchronize the initial page table after setting up the cpu entry
area. Instead of adding yet another copy of the same code, move it to a
function and invoke it from the various places.
It needs to be investigated if the existing calls in setup_arch() and
setup_per_cpu_areas() can be replaced by the later invocation from
setup_cpu_entry_areas(), but that's beyond the scope of this fix.
Fixes: 92a0f81d89 ("x86/cpu_entry_area: Move it out of the fixmap")
Reported-by: Woody Suwalski <terraluna977@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Woody Suwalski <terraluna977@gmail.com>
Cc: William Grant <william.grant@canonical.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1802282137290.1392@nanos.tec.linutronix.de
After initmem has been freed, any jump labels in __init code are
prevented from being written to by the kernel_text_address() check in
__jump_label_update(). However, this check is quite broad. If
kernel_text_address() were to return false for any other reason, the
jump label write would fail silently with no warning.
For jump labels in module init code, entry->code is set to zero to
indicate that the entry is disabled. Do the same thing for core kernel
init code. This makes the behavior more consistent, and will also make
it more straightforward to detect non-init jump label write failures in
the next patch.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/c52825c73f3a174e8398b6898284ec20d4deb126.1519051220.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We can also move the CLD, SWAPGS, and the switch_to_thread_stack() call
to the interrupt_entry() helper function. As we do not want call depths
of two, convert switch_to_thread_stack() to a macro.
However, switch_to_thread_stack() has another user in entry_64_compat.S,
which currently expects it to be a function. To keep the code changes
in this patch minimal, create a wrapper function.
The switch to a macro means that there is some binary code duplication
if CONFIG_IA32_EMULATION=y is enabled. Therefore, the size reduction
differs whether CONFIG_IA32_EMULATION is enabled or not:
CONFIG_IA32_EMULATION=y (-0.13k):
text data bss dec hex filename
17158 0 0 17158 4306 entry_64.o-orig
17028 0 0 17028 4284 entry_64.o
CONFIG_IA32_EMULATION=n (-0.27k):
text data bss dec hex filename
17158 0 0 17158 4306 entry_64.o-orig
16882 0 0 16882 41f2 entry_64.o
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: dan.j.williams@intel.com
Link: http://lkml.kernel.org/r/20180220210113.6725-4-linux@dominikbrodowski.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Moving the switch to IRQ stack from the interrupt macro to the helper
function requires some trickery: All ENTER_IRQ_STACK really cares about
is where the "original" stack -- meaning the GP registers etc. -- is
stored. Therefore, we need to offset the stored RSP value by 8 whenever
ENTER_IRQ_STACK is called from within a function. In such cases, and
after switching to the IRQ stack, we need to push the "original" return
address (i.e. the return address from the call to the interrupt entry
function) to the IRQ stack.
This trickery allows us to carve another .85k from the text size (it
would be more except for the additional unwind hints):
text data bss dec hex filename
18006 0 0 18006 4656 entry_64.o-orig
17158 0 0 17158 4306 entry_64.o
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: dan.j.williams@intel.com
Link: http://lkml.kernel.org/r/20180220210113.6725-3-linux@dominikbrodowski.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
