Re: [PATCH v21 06/26] x86/cet: Add control-protection fault handler

Yu, Yu-cheng
2021-02-24T16:45:56Z

On 2/24/2021 8:13 AM, Borislav Petkov wrote:
> On Wed, Feb 17, 2021 at 02:27:10PM -0800, Yu-cheng Yu wrote:
>> +/*
>> + * When a control protection exception occurs, send a signal to the responsible
>> + * application. Currently, control protection is only enabled for user mode.
>> + * This exception should not come from kernel mode.
>> + */
>> +DEFINE_IDTENTRY_ERRORCODE(exc_control_protection)
>> +{
>> + static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL,
>> + DEFAULT_RATELIMIT_BURST);

[...]

>> +
>> + rdmsrl(MSR_IA32_PL3_SSP, ssp);
>> + pr_emerg("%s[%d] control protection ip:%lx sp:%lx ssp:%lx error:%lx(%s)",
>> + tsk->comm, task_pid_nr(tsk),
>> + regs->ip, regs->sp, ssp, error_code,
>> + control_protection_err[err]);
>> + print_vma_addr(KERN_CONT " in ", regs->ip);
>> + pr_cont("\n");
>> + }
>> +
>> + force_sig_fault(SIGSEGV, SEGV_CPERR,
>> + (void __user *)uprobe_get_trap_addr(regs));
>
> Why is this calling an uprobes function?
>

I will change it to error_get_trap_addr().

> Also, do not break that line even if it is longer than 80.
>
>> + 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
>
> I still don't see the patch adding this to the manpage of sigaction(2).
>
> There's a git repo there: https://www.kernel.org/doc/man-pages/
>
> and I'm pretty sure Michael takes patches.
>

I will send a patch.

--
Yu-cheng