[PATCH v4 07/13] task_isolation: arch/x86: enable task isolation functionality

Alex Belits
2020-07-22T14:55:01Z

In prepare_exit_to_usermode(), run cleanup for tasks exited fromi
isolation and call task_isolation_start() for tasks that entered
TIF_TASK_ISOLATION.

In syscall_trace_enter(), add the necessary support for reporting
syscalls for task-isolation processes.

Add task_isolation_remote() calls for the kernel exception types
that do not result in signals, namely non-signalling page faults.

Add task_isolation_kernel_enter() calls to interrupt and syscall
entry handlers.

This mechanism relies on calls to functions that call
task_isolation_kernel_enter() early after entry into kernel. Those
functions are:

enter_from_user_mode()
called from do_syscall_64(), do_int80_syscall_32(),
do_fast_syscall_32(), idtentry_enter_user(),
idtentry_enter_cond_rcu()
idtentry_enter_cond_rcu()
called from non-raw IDT macros and other entry points
idtentry_enter_user()
nmi_enter()
xen_call_function_interrupt()
xen_call_function_single_interrupt()
xen_irq_work_interrupt()

Signed-off-by: Chris Metcalf <cmetcalf@mellanox.com>
[abelits@marvell.com: adapted for kernel 5.8]
Signed-off-by: Alex Belits <abelits@marvell.com>
---
arch/x86/Kconfig | 1 +
arch/x86/entry/common.c | 20 +++++++++++++++++++-
arch/x86/include/asm/barrier.h | 2 ++
arch/x86/include/asm/thread_info.h | 4 +++-
arch/x86/kernel/apic/ipi.c | 2 ++
arch/x86/mm/fault.c | 4 ++++
arch/x86/xen/smp.c | 3 +++
arch/x86/xen/smp_pv.c | 2 ++
8 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 883da0abf779..3a80142f85c8 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -149,6 +149,7 @@ config X86
select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
select HAVE_ARCH_PREL32_RELOCATIONS
select HAVE_ARCH_SECCOMP_FILTER
+ select HAVE_ARCH_TASK_ISOLATION
select HAVE_ARCH_THREAD_STRUCT_WHITELIST
select HAVE_ARCH_STACKLEAK
select HAVE_ARCH_TRACEHOOK
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index f09288431f28..ab94d90a2bd5 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -26,6 +26,7 @@
#include <linux/livepatch.h>
#include <linux/syscalls.h>
#include <linux/uaccess.h>
+#include <linux/isolation.h>

#ifdef CONFIG_XEN_PV
#include <xen/xen-ops.h>
@@ -86,6 +87,7 @@ static noinstr void enter_from_user_mode(void)
{
enum ctx_state state = ct_state();

+ task_isolation_kernel_enter();
lockdep_hardirqs_off(CALLER_ADDR0);
user_exit_irqoff();

@@ -97,6 +99,7 @@ static noinstr void enter_from_user_mode(void)
#else
static __always_inline void enter_from_user_mode(void)
{
+ task_isolation_kernel_enter();
lockdep_hardirqs_off(CALLER_ADDR0);
instrumentation_begin();
trace_hardirqs_off_finish();
@@ -161,6 +164,15 @@ static long syscall_trace_enter(struct pt_regs *regs)
return -1L;
}

+ /*
+ * In task isolation mode, we may prevent the syscall from
+ * running, and if so we also deliver a signal to the process.
+ */
+ if (work & _TIF_TASK_ISOLATION) {
+ if (task_isolation_syscall(regs->orig_ax) == -1)
+ return -1L;
+ work &= ~_TIF_TASK_ISOLATION;
+ }
#ifdef CONFIG_SECCOMP
/*
* Do seccomp after ptrace, to catch any tracer changes.
@@ -263,6 +275,8 @@ static void __prepare_exit_to_usermode(struct pt_regs *regs)
lockdep_assert_irqs_disabled();
lockdep_sys_exit();

+ task_isolation_check_run_cleanup();
+
cached_flags = READ_ONCE(ti->flags);

if (unlikely(cached_flags & EXIT_TO_USERMODE_LOOP_FLAGS))
@@ -278,6 +292,9 @@ static void __prepare_exit_to_usermode(struct pt_regs *regs)
if (unlikely(cached_flags & _TIF_NEED_FPU_LOAD))
switch_fpu_return();

+ if (cached_flags & _TIF_TASK_ISOLATION)
+ task_isolation_start();
+
#ifdef CONFIG_COMPAT
/*
* Compat syscalls set TS_COMPAT. Make sure we clear it before
@@ -597,7 +614,8 @@ bool noinstr idtentry_enter_cond_rcu(struct pt_regs *regs)
check_user_regs(regs);
enter_from_user_mode();
return false;
- }
+ } else
+ task_isolation_kernel_enter();

/*
* If this entry hit the idle task invoke rcu_irq_enter() whether
diff --git a/arch/x86/include/asm/barrier.h b/arch/x86/include/asm/barrier.h
index 7f828fe49797..5be6ca0519fc 100644
--- a/arch/x86/include/asm/barrier.h
+++ b/arch/x86/include/asm/barrier.h
@@ -4,6 +4,7 @@

#include <asm/alternative.h>
#include <asm/nops.h>
+#include <asm/processor.h>

/*
* Force strict CPU ordering.
@@ -53,6 +54,7 @@ static inline unsigned long array_index_mask_nospec(unsigned long index,

#define dma_rmb() barrier()
#define dma_wmb() barrier()
+#define instr_sync() sync_core()

#ifdef CONFIG_X86_32
#define __smp_mb() asm volatile("lock; addl $0,-4(%%esp)" ::: "memory", "cc")
diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
index 8de8ceccb8bc..6dd1a5cc286d 100644
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -93,6 +93,7 @@ struct thread_info {
#define TIF_NOTSC 16 /* TSC is not accessible in userland */
#define TIF_IA32 17 /* IA32 compatibility process */
#define TIF_SLD 18 /* Restore split lock detection on context switch */
+#define TIF_TASK_ISOLATION 19 /* task isolation enabled for task */
#define TIF_MEMDIE 20 /* is terminating due to OOM killer */
#define TIF_POLLING_NRFLAG 21 /* idle is polling for TIF_NEED_RESCHED */
#define TIF_IO_BITMAP 22 /* uses I/O bitmap */
@@ -123,6 +124,7 @@ struct thread_info {
#define _TIF_NOTSC (1 << TIF_NOTSC)
#define _TIF_IA32 (1 << TIF_IA32)
#define _TIF_SLD (1 << TIF_SLD)
+#define _TIF_TASK_ISOLATION (1 << TIF_TASK_ISOLATION)
#define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
#define _TIF_IO_BITMAP (1 << TIF_IO_BITMAP)
#define _TIF_FORCED_TF (1 << TIF_FORCED_TF)
@@ -136,7 +138,7 @@ struct thread_info {
/* Work to do before invoking the actual syscall. */
#define _TIF_WORK_SYSCALL_ENTRY \
(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT | \
- _TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT)
+ _TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT | _TIF_TASK_ISOLATION)

/* flags to check in __switch_to() */
#define _TIF_WORK_CTXSW_BASE \
diff --git a/arch/x86/kernel/apic/ipi.c b/arch/x86/kernel/apic/ipi.c
index 6ca0f91372fd..b4dfaad6a440 100644
--- a/arch/x86/kernel/apic/ipi.c
+++ b/arch/x86/kernel/apic/ipi.c
@@ -2,6 +2,7 @@

#include <linux/cpumask.h>
#include <linux/smp.h>
+#include <linux/isolation.h>

#include "local.h"

@@ -67,6 +68,7 @@ void native_smp_send_reschedule(int cpu)
WARN(1, "sched: Unexpected reschedule of offline CPU#%d!\n", cpu);
return;
}
+ task_isolation_remote(cpu, "reschedule IPI");
apic->send_IPI(cpu, RESCHEDULE_VECTOR);
}

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 1ead568c0101..e16a4f5c7e57 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/isolation.h> /* task_isolation_interrupt */

#include <asm/cpufeature.h> /* boot_cpu_has, ... */
#include <asm/traps.h> /* dotraplinkage, ... */
@@ -1332,6 +1333,9 @@ void do_user_addr_fault(struct pt_regs *regs,
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address);
}

+ /* No signal was generated, but notify task-isolation tasks. */
+ task_isolation_interrupt("page fault at %#lx", address);
+
check_v8086_mode(regs, address, tsk);
}
NOKPROBE_SYMBOL(do_user_addr_fault);
diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
index 2097fa0ebdb5..9a3a9bae7d06 100644
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -4,6 +4,7 @@
#include <linux/slab.h>
#include <linux/cpumask.h>
#include <linux/percpu.h>
+#include <linux/isolation.h>

#include <xen/events.h>

@@ -265,6 +266,7 @@ void xen_send_IPI_allbutself(int vector)

static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id)
{
+ task_isolation_kernel_enter();
irq_enter();
generic_smp_call_function_interrupt();
inc_irq_stat(irq_call_count);
@@ -275,6 +277,7 @@ static irqreturn_t xen_call_function_interrupt(int irq, void *dev_id)

static irqreturn_t xen_call_function_single_interrupt(int irq, void *dev_id)
{
+ task_isolation_kernel_enter();
irq_enter();
generic_smp_call_function_single_interrupt();
inc_irq_stat(irq_call_count);
diff --git a/arch/x86/xen/smp_pv.c b/arch/x86/xen/smp_pv.c
index 171aff1b11f2..d71d3cc36c51 100644
--- a/arch/x86/xen/smp_pv.c
+++ b/arch/x86/xen/smp_pv.c
@@ -24,6 +24,7 @@
#include <linux/cpuhotplug.h>
#include <linux/stackprotector.h>
#include <linux/pgtable.h>
+#include <linux/isolation.h>

#include <asm/paravirt.h>
#include <asm/idtentry.h>
@@ -482,6 +483,7 @@ static void xen_pv_stop_other_cpus(int wait)

static irqreturn_t xen_irq_work_interrupt(int irq, void *dev_id)
{
+ task_isolation_kernel_enter();
irq_enter();
irq_work_run();
inc_irq_stat(apic_irq_work_irqs);
--
2.26.2