diff options
Diffstat (limited to 'arch/x86/entry/common.c')
| -rw-r--r-- | arch/x86/entry/common.c | 140 |
1 files changed, 35 insertions, 105 deletions
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index ec138e538c44..bdd9cc59d20f 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -31,19 +31,12 @@ #define CREATE_TRACE_POINTS #include <trace/events/syscalls.h> -static struct thread_info *pt_regs_to_thread_info(struct pt_regs *regs) -{ - unsigned long top_of_stack = - (unsigned long)(regs + 1) + TOP_OF_KERNEL_STACK_PADDING; - return (struct thread_info *)(top_of_stack - THREAD_SIZE); -} - #ifdef CONFIG_CONTEXT_TRACKING /* Called on entry from user mode with IRQs off. */ -__visible void enter_from_user_mode(void) +__visible inline void enter_from_user_mode(void) { CT_WARN_ON(ct_state() != CONTEXT_USER); - user_exit(); + user_exit_irqoff(); } #else static inline void enter_from_user_mode(void) {} @@ -64,22 +57,16 @@ static void do_audit_syscall_entry(struct pt_regs *regs, u32 arch) } /* - * We can return 0 to resume the syscall or anything else to go to phase - * 2. If we resume the syscall, we need to put something appropriate in - * regs->orig_ax. - * - * NB: We don't have full pt_regs here, but regs->orig_ax and regs->ax - * are fully functional. - * - * For phase 2's benefit, our return value is: - * 0: resume the syscall - * 1: go to phase 2; no seccomp phase 2 needed - * anything else: go to phase 2; pass return value to seccomp + * Returns the syscall nr to run (which should match regs->orig_ax) or -1 + * to skip the syscall. */ -unsigned long syscall_trace_enter_phase1(struct pt_regs *regs, u32 arch) +static long syscall_trace_enter(struct pt_regs *regs) { - struct thread_info *ti = pt_regs_to_thread_info(regs); + u32 arch = in_ia32_syscall() ? AUDIT_ARCH_I386 : AUDIT_ARCH_X86_64; + + struct thread_info *ti = current_thread_info(); unsigned long ret = 0; + bool emulated = false; u32 work; if (IS_ENABLED(CONFIG_DEBUG_ENTRY)) @@ -87,11 +74,19 @@ unsigned long syscall_trace_enter_phase1(struct pt_regs *regs, u32 arch) work = ACCESS_ONCE(ti->flags) & _TIF_WORK_SYSCALL_ENTRY; + if (unlikely(work & _TIF_SYSCALL_EMU)) + emulated = true; + + if ((emulated || (work & _TIF_SYSCALL_TRACE)) && + tracehook_report_syscall_entry(regs)) + return -1L; + + if (emulated) + return -1L; + #ifdef CONFIG_SECCOMP /* - * Do seccomp first -- it should minimize exposure of other - * code, and keeping seccomp fast is probably more valuable - * than the rest of this. + * Do seccomp after ptrace, to catch any tracer changes. */ if (work & _TIF_SECCOMP) { struct seccomp_data sd; @@ -118,69 +113,12 @@ unsigned long syscall_trace_enter_phase1(struct pt_regs *regs, u32 arch) sd.args[5] = regs->bp; } - BUILD_BUG_ON(SECCOMP_PHASE1_OK != 0); - BUILD_BUG_ON(SECCOMP_PHASE1_SKIP != 1); - - ret = seccomp_phase1(&sd); - if (ret == SECCOMP_PHASE1_SKIP) { - regs->orig_ax = -1; - ret = 0; - } else if (ret != SECCOMP_PHASE1_OK) { - return ret; /* Go directly to phase 2 */ - } - - work &= ~_TIF_SECCOMP; + ret = __secure_computing(&sd); + if (ret == -1) + return ret; } #endif - /* Do our best to finish without phase 2. */ - if (work == 0) - return ret; /* seccomp and/or nohz only (ret == 0 here) */ - -#ifdef CONFIG_AUDITSYSCALL - if (work == _TIF_SYSCALL_AUDIT) { - /* - * If there is no more work to be done except auditing, - * then audit in phase 1. Phase 2 always audits, so, if - * we audit here, then we can't go on to phase 2. - */ - do_audit_syscall_entry(regs, arch); - return 0; - } -#endif - - return 1; /* Something is enabled that we can't handle in phase 1 */ -} - -/* Returns the syscall nr to run (which should match regs->orig_ax). */ -long syscall_trace_enter_phase2(struct pt_regs *regs, u32 arch, - unsigned long phase1_result) -{ - struct thread_info *ti = pt_regs_to_thread_info(regs); - long ret = 0; - u32 work = ACCESS_ONCE(ti->flags) & _TIF_WORK_SYSCALL_ENTRY; - - if (IS_ENABLED(CONFIG_DEBUG_ENTRY)) - BUG_ON(regs != task_pt_regs(current)); - -#ifdef CONFIG_SECCOMP - /* - * Call seccomp_phase2 before running the other hooks so that - * they can see any changes made by a seccomp tracer. - */ - if (phase1_result > 1 && seccomp_phase2(phase1_result)) { - /* seccomp failures shouldn't expose any additional code. */ - return -1; - } -#endif - - if (unlikely(work & _TIF_SYSCALL_EMU)) - ret = -1L; - - if ((ret || test_thread_flag(TIF_SYSCALL_TRACE)) && - tracehook_report_syscall_entry(regs)) - ret = -1L; - if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT))) trace_sys_enter(regs, regs->orig_ax); @@ -189,17 +127,6 @@ long syscall_trace_enter_phase2(struct pt_regs *regs, u32 arch, return ret ?: regs->orig_ax; } -long syscall_trace_enter(struct pt_regs *regs) -{ - u32 arch = in_ia32_syscall() ? AUDIT_ARCH_I386 : AUDIT_ARCH_X86_64; - unsigned long phase1_result = syscall_trace_enter_phase1(regs, arch); - - if (phase1_result == 0) - return regs->orig_ax; - else - return syscall_trace_enter_phase2(regs, arch, phase1_result); -} - #define EXIT_TO_USERMODE_LOOP_FLAGS \ (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_UPROBE | \ _TIF_NEED_RESCHED | _TIF_USER_RETURN_NOTIFY) @@ -239,18 +166,17 @@ static void exit_to_usermode_loop(struct pt_regs *regs, u32 cached_flags) /* Disable IRQs and retry */ local_irq_disable(); - cached_flags = READ_ONCE(pt_regs_to_thread_info(regs)->flags); + cached_flags = READ_ONCE(current_thread_info()->flags); if (!(cached_flags & EXIT_TO_USERMODE_LOOP_FLAGS)) break; - } } /* Called with IRQs disabled. */ __visible inline void prepare_exit_to_usermode(struct pt_regs *regs) { - struct thread_info *ti = pt_regs_to_thread_info(regs); + struct thread_info *ti = current_thread_info(); u32 cached_flags; if (IS_ENABLED(CONFIG_PROVE_LOCKING) && WARN_ON(!irqs_disabled())) @@ -270,11 +196,15 @@ __visible inline void prepare_exit_to_usermode(struct pt_regs *regs) * handling, because syscall restart has a fixup for compat * syscalls. The fixup is exercised by the ptrace_syscall_32 * selftest. + * + * We also need to clear TS_REGS_POKED_I386: the 32-bit tracer + * special case only applies after poking regs and before the + * very next return to user mode. */ - ti->status &= ~TS_COMPAT; + current->thread.status &= ~(TS_COMPAT|TS_I386_REGS_POKED); #endif - user_enter(); + user_enter_irqoff(); } #define SYSCALL_EXIT_WORK_FLAGS \ @@ -309,7 +239,7 @@ static void syscall_slow_exit_work(struct pt_regs *regs, u32 cached_flags) */ __visible inline void syscall_return_slowpath(struct pt_regs *regs) { - struct thread_info *ti = pt_regs_to_thread_info(regs); + struct thread_info *ti = current_thread_info(); u32 cached_flags = READ_ONCE(ti->flags); CT_WARN_ON(ct_state() != CONTEXT_KERNEL); @@ -332,7 +262,7 @@ __visible inline void syscall_return_slowpath(struct pt_regs *regs) #ifdef CONFIG_X86_64 __visible void do_syscall_64(struct pt_regs *regs) { - struct thread_info *ti = pt_regs_to_thread_info(regs); + struct thread_info *ti = current_thread_info(); unsigned long nr = regs->orig_ax; enter_from_user_mode(); @@ -365,11 +295,11 @@ __visible void do_syscall_64(struct pt_regs *regs) */ static __always_inline void do_syscall_32_irqs_on(struct pt_regs *regs) { - struct thread_info *ti = pt_regs_to_thread_info(regs); + struct thread_info *ti = current_thread_info(); unsigned int nr = (unsigned int)regs->orig_ax; #ifdef CONFIG_IA32_EMULATION - ti->status |= TS_COMPAT; + current->thread.status |= TS_COMPAT; #endif if (READ_ONCE(ti->flags) & _TIF_WORK_SYSCALL_ENTRY) { |