[PATCH v12 13/13] arch/arm64: enable task isolation functionality
From: Chris Metcalf <hidden>
Date: 2016-04-05 17:40:28
Also in:
lkml
Subsystem:
arm64 port (aarch64 architecture), ptrace support, the rest · Maintainers:
Catalin Marinas, Will Deacon, Oleg Nesterov, Linus Torvalds
In do_notify_resume(), 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. To ensure we always call task_isolation_enter() when returning to userspace, add _TIF_TASK_ISOLATION to _TIF_WORK_MASK, while leaving the old bitmask value as _TIF_WORK_LOOP_MASK to check while looping. 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_cross_call() routine so that it checks for isolated tasks and generates a suitable warning if we are about to disturb one of them in strict or debug mode. Finally, add an explicit check for STRICT mode in do_mem_abort() to handle the case of page faults. Signed-off-by: Chris Metcalf <redacted> --- arch/arm64/Kconfig | 1 + arch/arm64/include/asm/thread_info.h | 5 ++++- arch/arm64/kernel/ptrace.c | 15 ++++++++++++--- arch/arm64/kernel/signal.c | 10 ++++++++++ arch/arm64/kernel/smp.c | 2 ++ arch/arm64/mm/fault.c | 4 ++++ 6 files changed, 33 insertions(+), 4 deletions(-)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 4f436220384f..ec033abee9d5 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig@@ -57,6 +57,7 @@ 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_BPF_JIT select HAVE_C_RECORDMCOUNT
diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
index abd64bd1f6d9..bdc6426b9968 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h@@ -109,6 +109,7 @@ static inline struct thread_info *current_thread_info(void) #define TIF_NEED_RESCHED 1 #define TIF_NOTIFY_RESUME 2 /* callback before returning to user */ #define TIF_FOREIGN_FPSTATE 3 /* CPU's FP state is not current's */ +#define TIF_TASK_ISOLATION 4 #define TIF_NOHZ 7 #define TIF_SYSCALL_TRACE 8 #define TIF_SYSCALL_AUDIT 9
@@ -124,6 +125,7 @@ static inline struct thread_info *current_thread_info(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)
@@ -132,7 +134,8 @@ static inline struct thread_info *current_thread_info(void) #define _TIF_32BIT (1 << TIF_32BIT) #define _TIF_WORK_MASK (_TIF_NEED_RESCHED | _TIF_SIGPENDING | \ - _TIF_NOTIFY_RESUME | _TIF_FOREIGN_FPSTATE) + _TIF_NOTIFY_RESUME | _TIF_FOREIGN_FPSTATE | \ + _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 3f6cd5c5234f..ae336065733d 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c@@ -37,6 +37,7 @@ #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>
@@ -1246,14 +1247,22 @@ static void tracehook_report_syscall(struct pt_regs *regs, asmlinkage int syscall_trace_enter(struct pt_regs *regs) { - /* Do the secure computing check first; failures should be fast. */ + unsigned long work = ACCESS_ONCE(current_thread_info()->flags); + + /* In isolation mode, we may prevent the syscall from running. */ + 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() == -1) return -1; - if (test_thread_flag(TIF_SYSCALL_TRACE)) + if (work & _TIF_SYSCALL_TRACE) tracehook_report_syscall(regs, PTRACE_SYSCALL_ENTER); - 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 404dd67080b9..f9b9b25636ca 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c@@ -25,6 +25,7 @@ #include <linux/uaccess.h> #include <linux/tracehook.h> #include <linux/ratelimit.h> +#include <linux/isolation.h> #include <asm/debug-monitors.h> #include <asm/elf.h>
@@ -424,9 +425,18 @@ asmlinkage void do_notify_resume(struct pt_regs *regs, if (thread_flags & _TIF_FOREIGN_FPSTATE) fpsimd_restore_current_state(); + + if (thread_flags & _TIF_TASK_ISOLATION) + task_isolation_enter(); } local_irq_disable(); thread_flags = READ_ONCE(current_thread_info()->flags); + + /* Clear task isolation from cached_flags manually. */ + if ((thread_flags & _TIF_TASK_ISOLATION) && + task_isolation_ready()) + thread_flags &= ~_TIF_TASK_ISOLATION; + } while (thread_flags & _TIF_WORK_MASK); }
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index b2d5f4ee9a1c..83ed6b5baa4d 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c@@ -37,6 +37,7 @@ #include <linux/completion.h> #include <linux/of.h> #include <linux/irq_work.h> +#include <linux/isolation.h> #include <asm/alternative.h> #include <asm/atomic.h>
@@ -710,6 +711,7 @@ static const char *ipi_types[NR_IPI] __tracepoint_string = { static void smp_cross_call(const struct cpumask *target, unsigned int ipinr) { trace_ipi_raise(target, ipi_types[ipinr]); + task_isolation_debug_cpumask(target); __smp_cross_call(target, ipinr); }
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 95df28bc875f..77f827b02c6d 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c@@ -29,6 +29,7 @@ #include <linux/sched.h> #include <linux/highmem.h> #include <linux/perf_event.h> +#include <linux/isolation.h> #include <asm/cpufeature.h> #include <asm/exception.h>
@@ -482,6 +483,9 @@ asmlinkage void __exception do_mem_abort(unsigned long addr, unsigned int esr, const struct fault_info *inf = fault_info + (esr & 63); struct siginfo info; + if (user_mode(regs)) + task_isolation_exception("%s at %#lx", inf->name, addr); + if (!inf->fn(addr, esr, regs)) return;
--
2.7.2