From: Eugene Syromiatnikov <esyr@redhat.com>
To: Yu-cheng Yu <yu-cheng.yu@intel.com>
Cc: x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
linux-mm@kvack.org, linux-arch@vger.kernel.org,
linux-api@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
Andy Lutomirski <luto@amacapital.net>,
Balbir Singh <bsingharora@gmail.com>,
Cyrill Gorcunov <gorcunov@gmail.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Florian Weimer <fweimer@redhat.com>,
"H.J. Lu" <hjl.tools@gmail.com>, Jann Horn <jannh@google.com>,
Jonathan Corbet <corbet@lwn.net>,
Kees Cook <keescook@chromium.org>,
Mike Kravetz <mike.kravetz@oracle.com>,
Nadav Amit <nadav.amit@gmail.com>,
Oleg Nesterov <oleg@redhat.com>, Pavel Machek <pavel@ucw.cz>,
Peter Zijlstra <peterz@infradead.org>,
Randy Dunlap <rdunlap@infradead.org>,
"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
Vedvyas Shanbhogue <vedvyas.shanbhogue@intel.com>
Subject: Re: [RFC PATCH v4 19/27] x86/cet/shstk: Introduce WRUSS instruction
Date: Wed, 3 Oct 2018 06:15:57 +0200 [thread overview]
Message-ID: <20181003041557.GA22724@asgard.redhat.com> (raw)
Message-ID: <20181003041557.vHYkqNOD_4P3HU_97SVUSmSS0NqmlFxGS0ACC4p52ko@z> (raw)
In-Reply-To: <20180921150351.20898-20-yu-cheng.yu@intel.com>
On Fri, Sep 21, 2018 at 08:03:43AM -0700, Yu-cheng Yu wrote:
> WRUSS is a new kernel-mode instruction but writes directly
> to user shadow stack memory. This is used to construct
> a return address on the shadow stack for the signal
> handler.
>
> This instruction can fault if the user shadow stack is
> invalid shadow stack memory. In that case, the kernel does
> fixup.
"a fixup"
>
> Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
> ---
> arch/x86/include/asm/special_insns.h | 32 ++++++++++++++++++++++++++++
> arch/x86/mm/fault.c | 9 ++++++++
> 2 files changed, 41 insertions(+)
>
> diff --git a/arch/x86/include/asm/special_insns.h b/arch/x86/include/asm/special_insns.h
> index 317fc59b512c..c04e68ef47da 100644
> --- a/arch/x86/include/asm/special_insns.h
> +++ b/arch/x86/include/asm/special_insns.h
> @@ -237,6 +237,38 @@ static inline void clwb(volatile void *__p)
> : [pax] "a" (p));
> }
>
> +#ifdef CONFIG_X86_INTEL_CET
> +#if defined(CONFIG_IA32_EMULATION) || defined(CONFIG_X86_X32)
> +static inline int write_user_shstk_32(unsigned long addr, unsigned int val)
> +{
> + asm_volatile_goto("1: wrussd %1, (%0)\n"
> + _ASM_EXTABLE(1b, %l[fail])
> + :: "r" (addr), "r" (val)
> + :: fail);
> + return 0;
> +fail:
> + return -1;
Should it...
> +}
> +#else
> +static inline int write_user_shstk_32(unsigned long addr, unsigned int val)
> +{
> + WARN_ONCE(1, "write_user_shstk_32 used but not supported.\n");
"is/was used"
> + return -EFAULT;
> +}
> +#endif
> +
> +static inline int write_user_shstk_64(unsigned long addr, unsigned long val)
> +{
> + asm_volatile_goto("1: wrussq %1, (%0)\n"
> + _ASM_EXTABLE(1b, %l[fail])
> + :: "r" (addr), "r" (val)
> + :: fail);
> + return 0;
> +fail:
> + return -1;
...and it be -EPERM, if -EFAULT was returned earlier for write_user_shstk_32?
> +}
> +#endif /* CONFIG_X86_INTEL_CET */
> +
> #define nop() asm volatile ("nop")
>
>
> diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
> index 7c3877a982f4..4d4ac57a4ba2 100644
> --- a/arch/x86/mm/fault.c
> +++ b/arch/x86/mm/fault.c
> @@ -1305,6 +1305,15 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code,
> error_code |= X86_PF_USER;
> flags |= FAULT_FLAG_USER;
> } else {
> + /*
> + * WRUSS is a kernel instrcution and but writes
"WRUSS is a kernel instruction but writes"
> + * to user shadow stack. When a fault occurs,
> + * both X86_PF_USER and X86_PF_SHSTK are set.
> + * Clear X86_PF_USER here.
> + */
> + if ((error_code & (X86_PF_USER | X86_PF_SHSTK)) ==
> + (X86_PF_USER | X86_PF_SHSTK))
> + error_code &= ~X86_PF_USER;
> if (regs->flags & X86_EFLAGS_IF)
> local_irq_enable();
> }
> --
> 2.17.1
>
next prev parent reply other threads:[~2018-10-03 11:02 UTC|newest]
Thread overview: 142+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-21 15:03 [RFC PATCH v4 00/27] Control Flow Enforcement: Shadow Stack Yu-cheng Yu
2018-09-21 15:03 ` Yu-cheng Yu
2018-09-21 15:03 ` [RFC PATCH v4 01/27] x86/cpufeatures: Add CPUIDs for Control-flow Enforcement Technology (CET) Yu-cheng Yu
2018-09-21 15:03 ` Yu-cheng Yu
2018-09-25 16:27 ` Peter Zijlstra
2018-09-25 16:27 ` Peter Zijlstra
2018-09-25 16:29 ` Yu-cheng Yu
2018-09-25 16:29 ` Yu-cheng Yu
2018-09-28 16:51 ` Borislav Petkov
2018-09-28 16:51 ` Borislav Petkov
2018-09-28 16:56 ` Yu-cheng Yu
2018-09-28 16:56 ` Yu-cheng Yu
2018-09-21 15:03 ` [RFC PATCH v4 02/27] x86/fpu/xstate: Change some names to separate XSAVES system and user states Yu-cheng Yu
2018-09-21 15:03 ` Yu-cheng Yu
2018-09-25 16:37 ` Peter Zijlstra
2018-09-25 16:37 ` Peter Zijlstra
2018-10-02 15:29 ` Borislav Petkov
2018-10-02 15:29 ` Borislav Petkov
2018-10-02 16:21 ` Yu-cheng Yu
2018-10-02 16:21 ` Yu-cheng Yu
2018-10-02 16:30 ` Dave Hansen
2018-10-02 16:30 ` Dave Hansen
2018-10-02 16:37 ` Borislav Petkov
2018-10-02 16:37 ` Borislav Petkov
2018-10-02 16:39 ` Dave Hansen
2018-10-02 16:39 ` Dave Hansen
2018-10-02 16:43 ` Yu-cheng Yu
2018-10-02 16:43 ` Yu-cheng Yu
2018-09-21 15:03 ` [RFC PATCH v4 03/27] x86/fpu/xstate: Enable XSAVES system states Yu-cheng Yu
2018-09-21 15:03 ` Yu-cheng Yu
2018-09-25 17:03 ` Peter Zijlstra
2018-09-25 17:03 ` Peter Zijlstra
2018-09-25 17:23 ` Yu-cheng Yu
2018-09-25 17:23 ` Yu-cheng Yu
2018-10-02 17:15 ` Borislav Petkov
2018-10-02 17:15 ` Borislav Petkov
2018-10-04 15:47 ` Yu-cheng Yu
2018-10-04 15:47 ` Yu-cheng Yu
2018-09-21 15:03 ` [RFC PATCH v4 04/27] x86/fpu/xstate: Add XSAVES system states for shadow stack Yu-cheng Yu
2018-09-21 15:03 ` Yu-cheng Yu
2018-09-21 15:03 ` [RFC PATCH v4 05/27] Documentation/x86: Add CET description Yu-cheng Yu
2018-09-21 15:03 ` Yu-cheng Yu
2018-09-21 15:03 ` [RFC PATCH v4 06/27] x86/cet: Control protection exception handler Yu-cheng Yu
2018-09-21 15:03 ` Yu-cheng Yu
2018-10-03 10:39 ` Eugene Syromiatnikov
2018-10-03 10:39 ` Eugene Syromiatnikov
2018-10-03 16:11 ` Yu-cheng Yu
2018-10-03 16:11 ` Yu-cheng Yu
2018-09-21 15:03 ` [RFC PATCH v4 07/27] x86/cet/shstk: Add Kconfig option for user-mode shadow stack Yu-cheng Yu
2018-09-21 15:03 ` Yu-cheng Yu
2018-09-21 15:03 ` [RFC PATCH v4 08/27] mm: Introduce VM_SHSTK for shadow stack memory Yu-cheng Yu
2018-09-21 15:03 ` Yu-cheng Yu
2018-09-21 15:03 ` [RFC PATCH v4 09/27] x86/mm: Change _PAGE_DIRTY to _PAGE_DIRTY_HW Yu-cheng Yu
2018-09-21 15:03 ` Yu-cheng Yu
2018-10-03 13:38 ` Matthew Wilcox
2018-10-03 13:38 ` Matthew Wilcox
2018-10-03 14:05 ` Dave Hansen
2018-10-03 14:05 ` Dave Hansen
2018-10-03 16:07 ` Yu-cheng Yu
2018-10-03 16:07 ` Yu-cheng Yu
2018-09-21 15:03 ` [RFC PATCH v4 10/27] drm/i915/gvt: Update _PAGE_DIRTY to _PAGE_DIRTY_BITS Yu-cheng Yu
2018-09-21 15:03 ` Yu-cheng Yu
2018-10-03 13:19 ` Eugene Syromiatnikov
2018-10-03 13:19 ` Eugene Syromiatnikov
2018-09-21 15:03 ` [RFC PATCH v4 11/27] x86/mm: Introduce _PAGE_DIRTY_SW Yu-cheng Yu
2018-09-21 15:03 ` Yu-cheng Yu
2018-09-21 15:03 ` [RFC PATCH v4 12/27] x86/mm: Modify ptep_set_wrprotect and pmdp_set_wrprotect for _PAGE_DIRTY_SW Yu-cheng Yu
2018-09-21 15:03 ` Yu-cheng Yu
2018-09-21 15:03 ` [RFC PATCH v4 13/27] x86/mm: Shadow stack page fault error checking Yu-cheng Yu
2018-09-21 15:03 ` Yu-cheng Yu
2018-09-21 15:03 ` [RFC PATCH v4 14/27] mm: Handle shadow stack page fault Yu-cheng Yu
2018-09-21 15:03 ` Yu-cheng Yu
2018-09-21 15:03 ` [RFC PATCH v4 15/27] mm: Handle THP/HugeTLB " Yu-cheng Yu
2018-09-21 15:03 ` Yu-cheng Yu
2018-09-21 15:03 ` [RFC PATCH v4 16/27] mm: Update can_follow_write_pte/pmd for shadow stack Yu-cheng Yu
2018-09-21 15:03 ` Yu-cheng Yu
2018-09-21 15:03 ` [RFC PATCH v4 17/27] mm: Introduce do_mmap_locked() Yu-cheng Yu
2018-09-21 15:03 ` Yu-cheng Yu
2018-09-21 15:03 ` [RFC PATCH v4 18/27] x86/cet/shstk: User-mode shadow stack support Yu-cheng Yu
2018-09-21 15:03 ` Yu-cheng Yu
2018-10-03 15:08 ` Eugene Syromiatnikov
2018-10-03 15:08 ` Eugene Syromiatnikov
2018-10-03 15:12 ` Yu-cheng Yu
2018-10-03 15:12 ` Yu-cheng Yu
2018-09-21 15:03 ` [RFC PATCH v4 19/27] x86/cet/shstk: Introduce WRUSS instruction Yu-cheng Yu
2018-09-21 15:03 ` Yu-cheng Yu
2018-10-03 4:15 ` Eugene Syromiatnikov [this message]
2018-10-03 4:15 ` Eugene Syromiatnikov
2018-09-21 15:03 ` [RFC PATCH v4 20/27] x86/cet/shstk: Signal handling for shadow stack Yu-cheng Yu
2018-09-21 15:03 ` Yu-cheng Yu
2018-10-03 14:36 ` Eugene Syromiatnikov
2018-10-03 14:36 ` Eugene Syromiatnikov
2018-10-03 16:46 ` Jann Horn
2018-10-03 16:46 ` Jann Horn
2018-09-21 15:03 ` [RFC PATCH v4 21/27] x86/cet/shstk: ELF header parsing of Shadow Stack Yu-cheng Yu
2018-09-21 15:03 ` Yu-cheng Yu
2018-10-03 23:27 ` Eugene Syromiatnikov
2018-10-03 23:27 ` Eugene Syromiatnikov
2018-10-09 21:15 ` Yu-cheng Yu
2018-10-09 21:15 ` Yu-cheng Yu
2018-10-15 23:40 ` Kees Cook
2018-10-15 23:40 ` Kees Cook
2018-10-16 17:23 ` Yu-cheng Yu
2018-10-16 17:23 ` Yu-cheng Yu
2018-09-21 15:03 ` [RFC PATCH v4 22/27] x86/cet/shstk: Handle thread shadow stack Yu-cheng Yu
2018-09-21 15:03 ` Yu-cheng Yu
2018-09-21 15:03 ` [RFC PATCH v4 23/27] mm/map: Add Shadow stack pages to memory accounting Yu-cheng Yu
2018-09-21 15:03 ` Yu-cheng Yu
2018-09-21 16:55 ` Randy Dunlap
2018-09-21 16:55 ` Randy Dunlap
2018-09-21 17:21 ` Yu-cheng Yu
2018-09-21 17:21 ` Yu-cheng Yu
2018-09-21 15:03 ` [RFC PATCH v4 24/27] mm/mmap: Create a guard area between VMAs Yu-cheng Yu
2018-09-21 15:03 ` Yu-cheng Yu
2018-10-03 4:56 ` Eugene Syromiatnikov
2018-10-03 4:56 ` Eugene Syromiatnikov
2018-10-03 5:36 ` Andy Lutomirski
2018-10-03 5:36 ` Andy Lutomirski
2018-10-03 16:00 ` Yu-cheng Yu
2018-10-03 16:00 ` Yu-cheng Yu
2018-10-03 16:18 ` Andy Lutomirski
2018-10-03 16:18 ` Andy Lutomirski
2018-10-03 16:32 ` Eugene Syromiatnikov
2018-10-03 16:32 ` Eugene Syromiatnikov
2018-10-03 16:40 ` Yu-cheng Yu
2018-10-03 16:40 ` Yu-cheng Yu
2018-10-03 16:52 ` Jann Horn
2018-10-03 16:52 ` Jann Horn
2018-10-03 21:21 ` Eugene Syromiatnikov
2018-10-03 21:21 ` Eugene Syromiatnikov
2018-09-21 15:03 ` [RFC PATCH v4 25/27] mm/mmap: Prevent Shadow Stack VMA merges Yu-cheng Yu
2018-09-21 15:03 ` Yu-cheng Yu
2018-09-21 15:03 ` [RFC PATCH v4 26/27] x86/cet/shstk: Add arch_prctl functions for Shadow Stack Yu-cheng Yu
2018-09-21 15:03 ` Yu-cheng Yu
2018-10-03 17:57 ` Eugene Syromiatnikov
2018-10-03 17:57 ` Eugene Syromiatnikov
2018-09-21 15:03 ` [RFC PATCH v4 27/27] x86/cet/shstk: Add Shadow Stack instructions to opcode map Yu-cheng Yu
2018-09-21 15:03 ` Yu-cheng Yu
2018-09-21 22:53 ` [RFC PATCH v4 00/27] Control Flow Enforcement: Shadow Stack Dave Hansen
2018-09-21 22:53 ` Dave Hansen
2018-09-24 15:25 ` Yu-cheng Yu
2018-09-24 15:25 ` Yu-cheng Yu
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