(cherry picked from commit 15d4507152)
The Indirect Branch Predictor Barrier (IBPB) is an indirect branch
control mechanism. It keeps earlier branches from influencing
later ones.
Unlike IBRS and STIBP, IBPB does not define a new mode of operation.
It's a command that ensures predicted branch targets aren't used after
the barrier. Although IBRS and IBPB are enumerated by the same CPUID
enumeration, IBPB is very different.
IBPB helps mitigate against three potential attacks:
* Mitigate guests from being attacked by other guests.
- This is addressed by issing IBPB when we do a guest switch.
* Mitigate attacks from guest/ring3->host/ring3.
These would require a IBPB during context switch in host, or after
VMEXIT. The host process has two ways to mitigate
- Either it can be compiled with retpoline
- If its going through context switch, and has set !dumpable then
there is a IBPB in that path.
(Tim's patch: https://patchwork.kernel.org/patch/10192871)
- The case where after a VMEXIT you return back to Qemu might make
Qemu attackable from guest when Qemu isn't compiled with retpoline.
There are issues reported when doing IBPB on every VMEXIT that resulted
in some tsc calibration woes in guest.
* Mitigate guest/ring0->host/ring0 attacks.
When host kernel is using retpoline it is safe against these attacks.
If host kernel isn't using retpoline we might need to do a IBPB flush on
every VMEXIT.
Even when using retpoline for indirect calls, in certain conditions 'ret'
can use the BTB on Skylake-era CPUs. There are other mitigations
available like RSB stuffing/clearing.
* IBPB is issued only for SVM during svm_free_vcpu().
VMX has a vmclear and SVM doesn't. Follow discussion here:
https://lkml.org/lkml/2018/1/15/146
Please refer to the following spec for more details on the enumeration
and control.
Refer here to get documentation about mitigations.
https://software.intel.com/en-us/side-channel-security-support
[peterz: rebase and changelog rewrite]
[karahmed: - rebase
- vmx: expose PRED_CMD if guest has it in CPUID
- svm: only pass through IBPB if guest has it in CPUID
- vmx: support !cpu_has_vmx_msr_bitmap()]
- vmx: support nested]
[dwmw2: Expose CPUID bit too (AMD IBPB only for now as we lack IBRS)
PRED_CMD is a write-only MSR]
Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: kvm@vger.kernel.org
Cc: Asit Mallick <asit.k.mallick@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Arjan Van De Ven <arjan.van.de.ven@intel.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Jun Nakajima <jun.nakajima@intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Link: http://lkml.kernel.org/r/1515720739-43819-6-git-send-email-ashok.raj@intel.com
Link: https://lkml.kernel.org/r/1517522386-18410-3-git-send-email-karahmed@amazon.de
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 904e14fb7c)
Place the MSR bitmap in struct loaded_vmcs, and update it in place
every time the x2apic or APICv state can change. This is rare and
the loop can handle 64 MSRs per iteration, in a similar fashion as
nested_vmx_prepare_msr_bitmap.
This prepares for choosing, on a per-VM basis, whether to intercept
the SPEC_CTRL and PRED_CMD MSRs.
Cc: stable@vger.kernel.org # prereq for Spectre mitigation
Suggested-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit c9f04407f2)
The host physical addresses of L1's Virtual APIC Page and Posted
Interrupt descriptor are loaded into the VMCS02. The CPU may write
to these pages via their host physical address while L2 is running,
bypassing address-translation-based dirty tracking (e.g. EPT write
protection). Mark them dirty on every exit from L2 to prevent them
from getting out of sync with dirty tracking.
Also mark the virtual APIC page and the posted interrupt descriptor
dirty when KVM is virtualizing posted interrupt processing.
Signed-off-by: David Matlack <dmatlack@google.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 42cf014d38 upstream.
kmap() can't fail, therefore it will always return a valid pointer. Let's
just get rid of the unnecessary checks.
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 4bf5d56d42)
I'm seeing build failures from the two newly introduced arrays that
are marked 'const' and '__initdata', which are mutually exclusive:
arch/x86/kernel/cpu/common.c:882:43: error: 'cpu_no_speculation' causes a section type conflict with 'e820_table_firmware_init'
arch/x86/kernel/cpu/common.c:895:43: error: 'cpu_no_meltdown' causes a section type conflict with 'e820_table_firmware_init'
The correct annotation is __initconst.
Fixes: fec9434a12 ("x86/pti: Do not enable PTI on CPUs which are not vulnerable to Meltdown")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Thomas Garnier <thgarnie@google.com>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Link: https://lkml.kernel.org/r/20180202213959.611210-1-arnd@arndb.de
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 7fcae1118f)
Despite the fact that all the other code there seems to be doing it, just
using set_cpu_cap() in early_intel_init() doesn't actually work.
For CPUs with PKU support, setup_pku() calls get_cpu_cap() after
c->c_init() has set those feature bits. That resets those bits back to what
was queried from the hardware.
Turning the bits off for bad microcode is easy to fix. That can just use
setup_clear_cpu_cap() to force them off for all CPUs.
I was less keen on forcing the feature bits *on* that way, just in case
of inconsistencies. I appreciate that the kernel is going to get this
utterly wrong if CPU features are not consistent, because it has already
applied alternatives by the time secondary CPUs are brought up.
But at least if setup_force_cpu_cap() isn't being used, we might have a
chance of *detecting* the lack of the corresponding bit and either
panicking or refusing to bring the offending CPU online.
So ensure that the appropriate feature bits are set within get_cpu_cap()
regardless of how many extra times it's called.
Fixes: 2961298e ("x86/cpufeatures: Clean up Spectre v2 related CPUID flags")
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: karahmed@amazon.de
Cc: peterz@infradead.org
Cc: bp@alien8.de
Link: https://lkml.kernel.org/r/1517322623-15261-1-git-send-email-dwmw@amazon.co.uk
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit b3bbfb3fb5)
For __get_user() paths, do not allow the kernel to speculate on the value
of a user controlled pointer. In addition to the 'stac' instruction for
Supervisor Mode Access Protection (SMAP), a barrier_nospec() causes the
access_ok() result to resolve in the pipeline before the CPU might take any
speculative action on the pointer value. Given the cost of 'stac' the
speculation barrier is placed after 'stac' to hopefully overlap the cost of
disabling SMAP with the cost of flushing the instruction pipeline.
Since __get_user is a major kernel interface that deals with user
controlled pointers, the __uaccess_begin_nospec() mechanism will prevent
speculative execution past an access_ok() permission check. While
speculative execution past access_ok() is not enough to lead to a kernel
memory leak, it is a necessary precondition.
To be clear, __uaccess_begin_nospec() is addressing a class of potential
problems near __get_user() usages.
Note, that while the barrier_nospec() in __uaccess_begin_nospec() is used
to protect __get_user(), pointer masking similar to array_index_nospec()
will be used for get_user() since it incorporates a bounds check near the
usage.
uaccess_try_nospec provides the same mechanism for get_user_try.
No functional changes.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Suggested-by: Andi Kleen <ak@linux.intel.com>
Suggested-by: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: kernel-hardening@lists.openwall.com
Cc: gregkh@linuxfoundation.org
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: alan@linux.intel.com
Link: https://lkml.kernel.org/r/151727415922.33451.5796614273104346583.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 37a8f7c383)
The TS_COMPAT bit is very hot and is accessed from code paths that mostly
also touch thread_info::flags. Move it into struct thread_info to improve
cache locality.
The only reason it was in thread_struct is that there was a brief period
during which arch-specific fields were not allowed in struct thread_info.
Linus suggested further changing:
ti->status &= ~(TS_COMPAT|TS_I386_REGS_POKED);
to:
if (unlikely(ti->status & (TS_COMPAT|TS_I386_REGS_POKED)))
ti->status &= ~(TS_COMPAT|TS_I386_REGS_POKED);
on the theory that frequently dirtying the cacheline even in pure 64-bit
code that never needs to modify status hurts performance. That could be a
reasonable followup patch, but I suspect it matters less on top of this
patch.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Kernel Hardening <kernel-hardening@lists.openwall.com>
Link: https://lkml.kernel.org/r/03148bcc1b217100e6e8ecf6a5468c45cf4304b6.1517164461.git.luto@kernel.org
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit e383095c7f)
If sysfs is disabled and RETPOLINE not defined:
arch/x86/kernel/cpu/bugs.c:97:13: warning: ‘spectre_v2_bad_module’ defined but not used
[-Wunused-variable]
static bool spectre_v2_bad_module;
Hide it.
Fixes: caf7501a1b ("module/retpoline: Warn about missing retpoline in module")
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit caf7501a1b)
There's a risk that a kernel which has full retpoline mitigations becomes
vulnerable when a module gets loaded that hasn't been compiled with the
right compiler or the right option.
To enable detection of that mismatch at module load time, add a module info
string "retpoline" at build time when the module was compiled with
retpoline support. This only covers compiled C source, but assembler source
or prebuilt object files are not checked.
If a retpoline enabled kernel detects a non retpoline protected module at
load time, print a warning and report it in the sysfs vulnerability file.
[ tglx: Massaged changelog ]
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: gregkh@linuxfoundation.org
Cc: torvalds@linux-foundation.org
Cc: jeyu@kernel.org
Cc: arjan@linux.intel.com
Link: https://lkml.kernel.org/r/20180125235028.31211-1-andi@firstfloor.org
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 794b4bc292 upstream.
With the 'encrypted' key type it was possible for userspace to provide a
data blob ending with a master key description shorter than expected,
e.g. 'keyctl add encrypted desc "new x" @s'. When validating such a
master key description, validate_master_desc() could read beyond the end
of the buffer. Fix this by using strncmp() instead of memcmp(). [Also
clean up the code to deduplicate some logic.]
Cc: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
Signed-off-by: Jin Qian <jinqian@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 5331aec1bf upstream.
This change resolves a new compile-time warning
when built as a loadable module:
WARNING: modpost: missing MODULE_LICENSE() in drivers/media/platform/soc_camera/soc_scale_crop.o
see include/linux/module.h for more information
This adds the license as "GPL", which matches the header of the file.
MODULE_DESCRIPTION and MODULE_AUTHOR are also added.
Signed-off-by: Jesse Chan <jc@linux.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
