[PATCH v16 09/13] arch/arm64: enable task isolation functionality
From: Chris Metcalf
Date: Fri Nov 03 2017 - 13:07:13 EST
In do_notify_resume(), call task_isolation_start() for
TIF_TASK_ISOLATION tasks. Add _TIF_TASK_ISOLATION to _TIF_WORK_MASK,
and define a local NOTIFY_RESUME_LOOP_FLAGS to check in the loop,
since we don't clear _TIF_TASK_ISOLATION in the loop.
We tweak syscall_trace_enter() slightly to carry the "flags"
value from current_thread_info()->flags for each of the tests,
rather than doing a volatile read from memory for each one. This
avoids a small overhead for each test, and in particular avoids
that overhead for TIF_NOHZ when TASK_ISOLATION is not enabled.
We instrument the smp_send_reschedule() routine so that it checks for
isolated tasks and generates a suitable warning if needed.
Finally, report on page faults in task-isolation processes in
do_page_faults().
Signed-off-by: Chris Metcalf <cmetcalf@xxxxxxxxxxxx>
---
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/thread_info.h | 5 ++++-
arch/arm64/kernel/ptrace.c | 18 +++++++++++++++---
arch/arm64/kernel/signal.c | 10 +++++++++-
arch/arm64/kernel/smp.c | 7 +++++++
arch/arm64/mm/fault.c | 5 +++++
6 files changed, 41 insertions(+), 5 deletions(-)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 0df64a6a56d4..d77ecdb29765 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -73,6 +73,7 @@ config ARM64
select HAVE_ARCH_MMAP_RND_BITS
select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
select HAVE_ARCH_SECCOMP_FILTER
+ select HAVE_ARCH_TASK_ISOLATION
select HAVE_ARCH_TRACEHOOK
select HAVE_ARCH_TRANSPARENT_HUGEPAGE
select HAVE_ARCH_VMAP_STACK
diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
index ddded6497a8a..9c749eca7384 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -82,6 +82,7 @@ void arch_setup_new_exec(void);
#define TIF_FOREIGN_FPSTATE 3 /* CPU's FP state is not current's */
#define TIF_UPROBE 4 /* uprobe breakpoint or singlestep */
#define TIF_FSCHECK 5 /* Check FS is USER_DS on return */
+#define TIF_TASK_ISOLATION 6
#define TIF_NOHZ 7
#define TIF_SYSCALL_TRACE 8
#define TIF_SYSCALL_AUDIT 9
@@ -97,6 +98,7 @@ void arch_setup_new_exec(void);
#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
#define _TIF_FOREIGN_FPSTATE (1 << TIF_FOREIGN_FPSTATE)
+#define _TIF_TASK_ISOLATION (1 << TIF_TASK_ISOLATION)
#define _TIF_NOHZ (1 << TIF_NOHZ)
#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
#define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT)
@@ -108,7 +110,8 @@ void arch_setup_new_exec(void);
#define _TIF_WORK_MASK (_TIF_NEED_RESCHED | _TIF_SIGPENDING | \
_TIF_NOTIFY_RESUME | _TIF_FOREIGN_FPSTATE | \
- _TIF_UPROBE | _TIF_FSCHECK)
+ _TIF_UPROBE | _TIF_FSCHECK | \
+ _TIF_TASK_ISOLATION)
#define _TIF_SYSCALL_WORK (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
_TIF_SYSCALL_TRACEPOINT | _TIF_SECCOMP | \
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 9cbb6123208f..e5c0d7cdaf4e 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -38,6 +38,7 @@
#include <linux/regset.h>
#include <linux/tracehook.h>
#include <linux/elf.h>
+#include <linux/isolation.h>
#include <asm/compat.h>
#include <asm/debug-monitors.h>
@@ -1371,14 +1372,25 @@ static void tracehook_report_syscall(struct pt_regs *regs,
asmlinkage int syscall_trace_enter(struct pt_regs *regs)
{
- if (test_thread_flag(TIF_SYSCALL_TRACE))
+ unsigned long work = READ_ONCE(current_thread_info()->flags);
+
+ if (work & _TIF_SYSCALL_TRACE)
tracehook_report_syscall(regs, PTRACE_SYSCALL_ENTER);
- /* Do the secure computing after ptrace; failures should be fast. */
+ /*
+ * 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->syscallno) == -1)
+ return -1;
+ }
+
+ /* Do the secure computing check early; failures should be fast. */
if (secure_computing(NULL) == -1)
return -1;
- if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
+ if (work & _TIF_SYSCALL_TRACEPOINT)
trace_sys_enter(regs, regs->syscallno);
audit_syscall_entry(regs->syscallno, regs->orig_x0, regs->regs[1],
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index 0bdc96c61bc0..d8f4904e992f 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -30,6 +30,7 @@
#include <linux/tracehook.h>
#include <linux/ratelimit.h>
#include <linux/syscalls.h>
+#include <linux/isolation.h>
#include <asm/debug-monitors.h>
#include <asm/elf.h>
@@ -741,6 +742,10 @@ static void do_signal(struct pt_regs *regs)
restore_saved_sigmask();
}
+#define NOTIFY_RESUME_LOOP_FLAGS \
+ (_TIF_NEED_RESCHED | _TIF_SIGPENDING | _TIF_NOTIFY_RESUME | \
+ _TIF_FOREIGN_FPSTATE | _TIF_UPROBE | _TIF_FSCHECK)
+
asmlinkage void do_notify_resume(struct pt_regs *regs,
unsigned int thread_flags)
{
@@ -777,5 +782,8 @@ asmlinkage void do_notify_resume(struct pt_regs *regs,
local_irq_disable();
thread_flags = READ_ONCE(current_thread_info()->flags);
- } while (thread_flags & _TIF_WORK_MASK);
+ } while (thread_flags & NOTIFY_RESUME_LOOP_FLAGS);
+
+ if (thread_flags & _TIF_TASK_ISOLATION)
+ task_isolation_start();
}
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 9f7195a5773e..4159c40de3b4 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -40,6 +40,7 @@
#include <linux/of.h>
#include <linux/irq_work.h>
#include <linux/kexec.h>
+#include <linux/isolation.h>
#include <asm/alternative.h>
#include <asm/atomic.h>
@@ -818,6 +819,7 @@ void arch_send_call_function_single_ipi(int cpu)
#ifdef CONFIG_ARM64_ACPI_PARKING_PROTOCOL
void arch_send_wakeup_ipi_mask(const struct cpumask *mask)
{
+ task_isolation_remote_cpumask(mask, "wakeup IPI");
smp_cross_call(mask, IPI_WAKEUP);
}
#endif
@@ -879,6 +881,9 @@ void handle_IPI(int ipinr, struct pt_regs *regs)
__inc_irq_stat(cpu, ipi_irqs[ipinr]);
}
+ task_isolation_interrupt("IPI type %d (%s)", ipinr,
+ ipinr < NR_IPI ? ipi_types[ipinr] : "unknown");
+
switch (ipinr) {
case IPI_RESCHEDULE:
scheduler_ipi();
@@ -941,12 +946,14 @@ void handle_IPI(int ipinr, struct pt_regs *regs)
void smp_send_reschedule(int cpu)
{
+ task_isolation_remote(cpu, "reschedule IPI");
smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
}
#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
void tick_broadcast(const struct cpumask *mask)
{
+ task_isolation_remote_cpumask(mask, "timer IPI");
smp_cross_call(mask, IPI_TIMER);
}
#endif
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index b64958b23a7f..bff2f84d5f4e 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -32,6 +32,7 @@
#include <linux/perf_event.h>
#include <linux/preempt.h>
#include <linux/hugetlb.h>
+#include <linux/isolation.h>
#include <asm/bug.h>
#include <asm/cmpxchg.h>
@@ -495,6 +496,10 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
*/
if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP |
VM_FAULT_BADACCESS)))) {
+ /* No signal was generated, but notify task-isolation tasks. */
+ if (user_mode(regs))
+ task_isolation_interrupt("page fault at %#lx", addr);
+
/*
* Major/minor page fault accounting is only done
* once. If we go through a retry, it is extremely
--
2.1.2