[PATCH v3 07/13] task_isolation: arch/arm64: enable task isolation functionality

Alex Belits
2020-04-09T15:24:11Z

From: Chris Metcalf <cmetcalf@mellanox.com>

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 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@mellanox.com>
[abelits@marvell.com: simplified to match kernel 5.6]
Signed-off-by: Alex Belits <abelits@marvell.com>
---
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/thread_info.h | 5 ++++-
arch/arm64/kernel/ptrace.c | 10 ++++++++++
arch/arm64/kernel/signal.c | 13 ++++++++++++-
arch/arm64/kernel/smp.c | 7 +++++++
arch/arm64/mm/fault.c | 5 +++++
6 files changed, 39 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 0b30e884e088..93b6aabc8be9 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -129,6 +129,7 @@ config ARM64
select HAVE_ARCH_PREL32_RELOCATIONS
select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ARCH_STACKLEAK
+ select HAVE_ARCH_TASK_ISOLATION
select HAVE_ARCH_THREAD_STRUCT_WHITELIST
select HAVE_ARCH_TRACEHOOK
select HAVE_ARCH_TRANSPARENT_HUGEPAGE
diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
index f0cec4160136..7563098eb5b2 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -63,6 +63,7 @@ void arch_release_task_struct(struct task_struct *tsk);
#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 /* syscall trace active */
#define TIF_SYSCALL_AUDIT 9 /* syscall auditing */
@@ -83,6 +84,7 @@ void arch_release_task_struct(struct task_struct *tsk);
#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)
@@ -96,7 +98,8 @@ void arch_release_task_struct(struct task_struct *tsk);

#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 cd6e5fa48b9c..b35b9b0c594c 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -29,6 +29,7 @@
#include <linux/regset.h>
#include <linux/tracehook.h>
#include <linux/elf.h>
+#include <linux/isolation.h>

#include <asm/compat.h>
#include <asm/cpufeature.h>
@@ -1836,6 +1837,15 @@ int syscall_trace_enter(struct pt_regs *regs)
return -1;
}

+ /*
+ * In task isolation mode, we may prevent the syscall from
+ * running, and if so we also deliver a signal to the process.
+ */
+ if (test_thread_flag(TIF_TASK_ISOLATION)) {
+ if (task_isolation_syscall(regs->syscallno) == -1)
+ return -1;
+ }
+
/* Do the secure computing after ptrace; failures should be fast. */
if (secure_computing() == -1)
return -1;
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index 339882db5a91..d488c91a4877 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -20,6 +20,7 @@
#include <linux/tracehook.h>
#include <linux/ratelimit.h>
#include <linux/syscalls.h>
+#include <linux/isolation.h>

#include <asm/daifflags.h>
#include <asm/debug-monitors.h>
@@ -898,6 +899,11 @@ 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 long thread_flags)
{
@@ -908,6 +914,8 @@ asmlinkage void do_notify_resume(struct pt_regs *regs,
*/
trace_hardirqs_off();

+ task_isolation_check_run_cleanup();
+
do {
/* Check valid user FS if needed */
addr_limit_user_check();
@@ -938,7 +946,10 @@ asmlinkage void do_notify_resume(struct pt_regs *regs,

local_daif_mask();
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();
}

unsigned long __ro_after_init signal_minsigstksz;
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index d4ed9a19d8fe..00f0f77adea0 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -32,6 +32,7 @@
#include <linux/irq_work.h>
#include <linux/kexec.h>
#include <linux/kvm_host.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
@@ -886,6 +888,9 @@ 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();
@@ -948,12 +953,14 @@ 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 85566d32958f..fc4b42c81c4f 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -23,6 +23,7 @@
#include <linux/perf_event.h>
#include <linux/preempt.h>
#include <linux/hugetlb.h>
+#include <linux/isolation.h>

#include <asm/acpi.h>
#include <asm/bug.h>
@@ -543,6 +544,10 @@ 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
--
2.20.1