Re: [PATCH v21 06/26] x86/cet: Add control-protection fault handler
From: Yu, Yu-cheng
Date: Wed Feb 24 2021 - 11:45:50 EST
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