linux-kernel - [RFC PATCH 5/7] x86/mm/fault: hook up SCI verification

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Date:   Fri, 26 Apr 2019 00:45:52 +0300
From:   Mike Rapoport <rppt@...ux.ibm.com>
To:     linux-kernel@...r.kernel.org
Cc:     Alexandre Chartre <alexandre.chartre@...cle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
        James Bottomley <James.Bottomley@...senpartnership.com>,
        Jonathan Adams <jwadams@...gle.com>,
        Kees Cook <keescook@...omium.org>,
        Paul Turner <pjt@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>, linux-mm@...ck.org,
        linux-security-module@...r.kernel.org, x86@...nel.org,
        Mike Rapoport <rppt@...ux.ibm.com>
Subject: [RFC PATCH 5/7] x86/mm/fault: hook up SCI verification

If a system call runs in isolated context, it's accesses to kernel code and
data will be verified by SCI susbsytem.

Signed-off-by: Mike Rapoport <rppt@...ux.ibm.com>
---
 arch/x86/mm/fault.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 9d5c75f..baa2a2f 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -18,6 +18,7 @@
 #include <linux/uaccess.h>		/* faulthandler_disabled()	*/
 #include <linux/efi.h>			/* efi_recover_from_page_fault()*/
 #include <linux/mm_types.h>
+#include <linux/sci.h>			/* sci_verify_and_map()		*/
 
 #include <asm/cpufeature.h>		/* boot_cpu_has, ...		*/
 #include <asm/traps.h>			/* dotraplinkage, ...		*/
@@ -1254,6 +1255,30 @@ static int fault_in_kernel_space(unsigned long address)
 	return address >= TASK_SIZE_MAX;
 }
 
+#ifdef CONFIG_SYSCALL_ISOLATION
+static int sci_fault(struct pt_regs *regs, unsigned long hw_error_code,
+		     unsigned long address)
+{
+	struct task_struct *tsk = current;
+
+	if (!tsk->in_isolated_syscall)
+		return 0;
+
+	if (!sci_verify_and_map(regs, address, hw_error_code)) {
+		this_cpu_write(cpu_sci.sci_syscall, 0);
+		no_context(regs, hw_error_code, address, SIGKILL, 0);
+	}
+
+	return 1;
+}
+#else
+static inline int sci_fault(struct pt_regs *regs, unsigned long hw_error_code,
+			    unsigned long address)
+{
+	return 0;
+}
+#endif
+
 /*
  * Called for all faults where 'address' is part of the kernel address
  * space.  Might get called for faults that originate from *code* that
@@ -1301,6 +1326,9 @@ do_kern_addr_fault(struct pt_regs *regs, unsigned long hw_error_code,
 	if (kprobes_fault(regs))
 		return;
 
+	if (sci_fault(regs, hw_error_code, address))
+		return;
+
 	/*
 	 * Note, despite being a "bad area", there are quite a few
 	 * acceptable reasons to get here, such as erratum fixups
-- 
2.7.4