[PATCH v13 06/12] arch/x86: enable task isolation functionality
From: Chris Metcalf
Date: Thu Jul 14 2016 - 16:49:06 EST
In exit_to_usermode_loop(), call task_isolation_ready() for
TIF_TASK_ISOLATION tasks when we are checking the thread-info flags,
and after we've handled the other work, call task_isolation_enter()
for such tasks.
In syscall_trace_enter_phase1(), we add the necessary support for
reporting syscalls for task-isolation processes.
We add strict reporting for the kernel exception types that do
not result in signals, namely non-signalling page faults and
non-signalling MPX fixups.
Signed-off-by: Chris Metcalf <cmetcalf@xxxxxxxxxxxx>
---
arch/x86/Kconfig | 1 +
arch/x86/entry/common.c | 18 +++++++++++++++++-
arch/x86/include/asm/thread_info.h | 2 ++
arch/x86/kernel/smp.c | 2 ++
arch/x86/kernel/traps.c | 3 +++
arch/x86/mm/fault.c | 5 +++++
6 files changed, 30 insertions(+), 1 deletion(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index d9a94da0c29f..0762072ba284 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -89,6 +89,7 @@ config X86
select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ARCH_SOFT_DIRTY if X86_64
+ select HAVE_ARCH_TASK_ISOLATION
select HAVE_ARCH_TRACEHOOK
select HAVE_ARCH_TRANSPARENT_HUGEPAGE
select HAVE_EBPF_JIT if X86_64
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index ec138e538c44..33fc40b29c9f 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -21,6 +21,7 @@
#include <linux/context_tracking.h>
#include <linux/user-return-notifier.h>
#include <linux/uprobes.h>
+#include <linux/isolation.h>
#include <asm/desc.h>
#include <asm/traps.h>
@@ -87,6 +88,13 @@ unsigned long syscall_trace_enter_phase1(struct pt_regs *regs, u32 arch)
work = ACCESS_ONCE(ti->flags) & _TIF_WORK_SYSCALL_ENTRY;
+ /* In isolation mode, we may prevent the syscall from running. */
+ if (work & _TIF_TASK_ISOLATION) {
+ if (task_isolation_syscall(regs->orig_ax) == -1)
+ return -1;
+ work &= ~_TIF_TASK_ISOLATION;
+ }
+
#ifdef CONFIG_SECCOMP
/*
* Do seccomp first -- it should minimize exposure of other
@@ -202,7 +210,7 @@ long syscall_trace_enter(struct pt_regs *regs)
#define EXIT_TO_USERMODE_LOOP_FLAGS \
(_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_UPROBE | \
- _TIF_NEED_RESCHED | _TIF_USER_RETURN_NOTIFY)
+ _TIF_NEED_RESCHED | _TIF_USER_RETURN_NOTIFY | _TIF_TASK_ISOLATION)
static void exit_to_usermode_loop(struct pt_regs *regs, u32 cached_flags)
{
@@ -236,11 +244,19 @@ static void exit_to_usermode_loop(struct pt_regs *regs, u32 cached_flags)
if (cached_flags & _TIF_USER_RETURN_NOTIFY)
fire_user_return_notifiers();
+ if (cached_flags & _TIF_TASK_ISOLATION)
+ task_isolation_enter();
+
/* Disable IRQs and retry */
local_irq_disable();
cached_flags = READ_ONCE(pt_regs_to_thread_info(regs)->flags);
+ /* Clear task isolation from cached_flags manually. */
+ if ((cached_flags & _TIF_TASK_ISOLATION) &&
+ task_isolation_ready())
+ cached_flags &= ~_TIF_TASK_ISOLATION;
+
if (!(cached_flags & EXIT_TO_USERMODE_LOOP_FLAGS))
break;
diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
index 30c133ac05cd..10167e086f3b 100644
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -97,6 +97,7 @@ struct thread_info {
#define TIF_SECCOMP 8 /* secure computing */
#define TIF_USER_RETURN_NOTIFY 11 /* notify kernel of userspace return */
#define TIF_UPROBE 12 /* breakpointed or singlestepping */
+#define TIF_TASK_ISOLATION 13 /* task isolation enabled for task */
#define TIF_NOTSC 16 /* TSC is not accessible in userland */
#define TIF_IA32 17 /* IA32 compatibility process */
#define TIF_FORK 18 /* ret_from_fork */
@@ -121,6 +122,7 @@ struct thread_info {
#define _TIF_SECCOMP (1 << TIF_SECCOMP)
#define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY)
#define _TIF_UPROBE (1 << TIF_UPROBE)
+#define _TIF_TASK_ISOLATION (1 << TIF_TASK_ISOLATION)
#define _TIF_NOTSC (1 << TIF_NOTSC)
#define _TIF_IA32 (1 << TIF_IA32)
#define _TIF_FORK (1 << TIF_FORK)
diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c
index 658777cf3851..e4ffd9581cdb 100644
--- a/arch/x86/kernel/smp.c
+++ b/arch/x86/kernel/smp.c
@@ -23,6 +23,7 @@
#include <linux/interrupt.h>
#include <linux/cpu.h>
#include <linux/gfp.h>
+#include <linux/isolation.h>
#include <asm/mtrr.h>
#include <asm/tlbflush.h>
@@ -125,6 +126,7 @@ static void native_smp_send_reschedule(int cpu)
WARN_ON(1);
return;
}
+ task_isolation_debug(cpu, "reschedule IPI");
apic->send_IPI(cpu, RESCHEDULE_VECTOR);
}
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 00f03d82e69a..4989af93bb33 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -36,6 +36,7 @@
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/io.h>
+#include <linux/isolation.h>
#ifdef CONFIG_EISA
#include <linux/ioport.h>
@@ -383,6 +384,8 @@ dotraplinkage void do_bounds(struct pt_regs *regs, long error_code)
case 2: /* Bound directory has invalid entry. */
if (mpx_handle_bd_fault())
goto exit_trap;
+ /* No signal was generated, but notify task-isolation tasks. */
+ task_isolation_quiet_exception("bounds check");
break; /* Success, it was handled */
case 1: /* Bound violation. */
info = mpx_generate_siginfo(regs);
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 7d1fa7cd2374..655b4ae0c9b8 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -14,6 +14,7 @@
#include <linux/prefetch.h> /* prefetchw */
#include <linux/context_tracking.h> /* exception_enter(), ... */
#include <linux/uaccess.h> /* faulthandler_disabled() */
+#include <linux/isolation.h> /* task_isolation_quiet_exception */
#include <asm/cpufeature.h> /* boot_cpu_has, ... */
#include <asm/traps.h> /* dotraplinkage, ... */
@@ -1397,6 +1398,10 @@ good_area:
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address);
}
+ /* No signal was generated, but notify task-isolation tasks. */
+ if (flags & PF_USER)
+ task_isolation_quiet_exception("page fault at %#lx", address);
+
check_v8086_mode(regs, address, tsk);
}
NOKPROBE_SYMBOL(__do_page_fault);
--
2.7.2