From: Borislav Petkov <bp@alien8.de>
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@kernel.org>,
Balbir Singh <bsingharora@gmail.com>,
Cyrill Gorcunov <gorcunov@gmail.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Eugene Syromiatnikov <esyr@redhat.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>,
Dave Martin <Dave.Martin@arm.com>,
Weijiang Yang <weijiang.yang@intel.com>,
Pengfei Xu <pengfei.xu@intel.com>,
"Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
Subject: Re: [PATCH v17 06/26] x86/cet: Add control-protection fault handler
Date: Tue, 19 Jan 2021 13:04:25 +0100 [thread overview]
Message-ID: <20210119120425.GI27433@zn.tnic> (raw)
In-Reply-To: <20201229213053.16395-7-yu-cheng.yu@intel.com>
On Tue, Dec 29, 2020 at 01:30:33PM -0800, Yu-cheng Yu wrote:
> @@ -606,6 +606,65 @@ DEFINE_IDTENTRY_ERRORCODE(exc_general_protection)
> cond_local_irq_disable(regs);
> }
>
> +#ifdef CONFIG_X86_CET_USER
> +static const char * const control_protection_err[] = {
> + "unknown",
> + "near-ret",
> + "far-ret/iret",
> + "endbranch",
> + "rstorssp",
> + "setssbsy",
> +};
> +
> +/*
> + * When a control protection exception occurs, send a signal to the responsible
> + * application. Currently, control protection is only enabled for the user
> + * mode. This exception should not come from the kernel mode.
> + */
There's no "the user mode" or "the kernel mode" - just "user mode" or
"kernel mode".
> +DEFINE_IDTENTRY_ERRORCODE(exc_control_protection)
> +{
> + struct task_struct *tsk;
> +
> + if (!user_mode(regs)) {
> + if (notify_die(DIE_TRAP, "control protection fault", regs,
> + error_code, X86_TRAP_CP, SIGSEGV) == NOTIFY_STOP)
> + return;
> + die("Upexpected/unsupported kernel control protection fault", regs, error_code);
Isn't the machine supposed to panic() here and do no further progress?
> + }
> +
> + cond_local_irq_enable(regs);
> +
> + if (!boot_cpu_has(X86_FEATURE_CET))
> + WARN_ONCE(1, "Control protection fault with CET support disabled\n");
> +
> + tsk = current;
> + tsk->thread.error_code = error_code;
> + tsk->thread.trap_nr = X86_TRAP_CP;
> +
> + if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) &&
> + printk_ratelimit()) {
WARNING: Prefer printk_ratelimited or pr_<level>_ratelimited to printk_ratelimit
#136: FILE: arch/x86/kernel/traps.c:645:
+ printk_ratelimit()) {
Still not using checkpatch?
> + unsigned int max_err;
> + unsigned long ssp;
> +
> + max_err = ARRAY_SIZE(control_protection_err) - 1;
> + if ((error_code < 0) || (error_code > max_err))
> + error_code = 0;
> +
> + rdmsrl(MSR_IA32_PL3_SSP, ssp);
> + pr_info("%s[%d] control protection ip:%lx sp:%lx ssp:%lx error:%lx(%s)",
If anything, all this stuff should be pr_emerg().
> + tsk->comm, task_pid_nr(tsk),
> + regs->ip, regs->sp, ssp, error_code,
> + control_protection_err[error_code]);
> + print_vma_addr(KERN_CONT " in ", regs->ip);
> + pr_cont("\n");
> + }
> +
> + force_sig_fault(SIGSEGV, SEGV_CPERR,
> + (void __user *)uprobe_get_trap_addr(regs));
> + cond_local_irq_disable(regs);
> +}
> +#endif
> +
> static bool do_int3(struct pt_regs *regs)
> {
> int res;
> diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
> index d2597000407a..1c2ea91284a0 100644
> --- a/include/uapi/asm-generic/siginfo.h
> +++ b/include/uapi/asm-generic/siginfo.h
> @@ -231,7 +231,8 @@ typedef struct siginfo {
> #define SEGV_ADIPERR 7 /* Precise MCD exception */
> #define SEGV_MTEAERR 8 /* Asynchronous ARM MTE error */
> #define SEGV_MTESERR 9 /* Synchronous ARM MTE exception */
> -#define NSIGSEGV 9
> +#define SEGV_CPERR 10 /* Control protection fault */
> +#define NSIGSEGV 10
This looks like it needs documentation in this manpage:
https://www.man7.org/linux/man-pages/man2/sigaction.2.html
+ Michael.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2021-01-19 12:13 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-29 21:30 [PATCH v17 00/26] Control-flow Enforcement: Shadow Stack Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 01/26] Documentation/x86: Add CET description Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 02/26] x86/cet/shstk: Add Kconfig option for user-mode control-flow protection Yu-cheng Yu
2021-01-19 11:06 ` Borislav Petkov
2021-01-19 18:10 ` Yu, Yu-cheng
2020-12-29 21:30 ` [PATCH v17 03/26] x86/cpufeatures: Add CET CPU feature flags for Control-flow Enforcement Technology (CET) Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 04/26] x86/cpufeatures: Introduce X86_FEATURE_CET and setup functions Yu-cheng Yu
2021-01-11 17:56 ` Borislav Petkov
2021-01-11 20:25 ` Yu, Yu-cheng
2021-01-11 23:09 ` Yu-cheng Yu
2021-01-12 0:09 ` Yu, Yu-cheng
2021-01-12 12:38 ` Borislav Petkov
2021-01-12 23:02 ` Yu, Yu-cheng
2021-01-13 10:04 ` Borislav Petkov
2020-12-29 21:30 ` [PATCH v17 05/26] x86/fpu/xstate: Introduce CET MSR and XSAVES supervisor states Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 06/26] x86/cet: Add control-protection fault handler Yu-cheng Yu
2021-01-19 12:04 ` Borislav Petkov [this message]
2021-01-19 19:36 ` Yu, Yu-cheng
2020-12-29 21:30 ` [PATCH v17 07/26] x86/mm: Remove _PAGE_DIRTY from kernel RO pages Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 08/26] x86/mm: Introduce _PAGE_COW Yu-cheng Yu
2021-01-21 18:44 ` Borislav Petkov
2021-01-21 20:16 ` Yu, Yu-cheng
2021-01-21 20:20 ` Dave Hansen
2021-01-21 20:26 ` Dave Hansen
2021-01-21 20:44 ` Yu, Yu-cheng
2021-01-21 20:41 ` Borislav Petkov
2021-01-21 21:40 ` Yu, Yu-cheng
2021-01-21 22:16 ` David Laight
2021-01-21 22:19 ` Randy Dunlap
2021-01-21 22:32 ` David Laight
2021-01-22 21:54 ` Yu, Yu-cheng
2020-12-29 21:30 ` [PATCH v17 09/26] drm/i915/gvt: Change _PAGE_DIRTY to _PAGE_DIRTY_BITS Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 10/26] x86/mm: Update pte_modify for _PAGE_COW Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 11/26] x86/mm: Update ptep_set_wrprotect() and pmdp_set_wrprotect() for transition from _PAGE_DIRTY to _PAGE_COW Yu-cheng Yu
2021-01-25 18:27 ` Borislav Petkov
2021-01-25 21:27 ` Yu, Yu-cheng
2021-01-25 21:55 ` Borislav Petkov
2021-01-25 22:18 ` Yu, Yu-cheng
2021-01-26 10:24 ` Borislav Petkov
2021-01-26 16:45 ` Yu, Yu-cheng
2021-01-26 8:46 ` Peter Zijlstra
2021-01-26 9:40 ` Peter Zijlstra
2021-01-26 16:43 ` Yu, Yu-cheng
2020-12-29 21:30 ` [PATCH v17 12/26] mm: Introduce VM_SHSTK for shadow stack memory Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 13/26] x86/mm: Shadow Stack page fault error checking Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 14/26] x86/mm: Update maybe_mkwrite() for shadow stack Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 15/26] mm: Fixup places that call pte_mkwrite() directly Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 16/26] mm: Add guard pages around a shadow stack Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 17/26] mm/mmap: Add shadow stack pages to memory accounting Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 18/26] mm: Update can_follow_write_pte() for shadow stack Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 19/26] mm: Re-introduce vm_flags to do_mmap() Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 20/26] x86/cet/shstk: User-mode shadow stack support Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 21/26] x86/cet/shstk: Handle signals for shadow stack Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 22/26] binfmt_elf: Define GNU_PROPERTY_X86_FEATURE_1_AND properties Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 23/26] ELF: Introduce arch_setup_elf_property() Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 24/26] x86/cet/shstk: Handle thread shadow stack Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 25/26] x86/cet/shstk: Add arch_prctl functions for " Yu-cheng Yu
2020-12-29 21:30 ` [PATCH v17 26/26] mm: Introduce PROT_SHSTK " Yu-cheng Yu
2021-01-04 20:08 ` [PATCH v17 00/26] Control-flow Enforcement: Shadow Stack Yu, Yu-cheng
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