From c87a85177e7a7f9a9ee32893fb99a928e02fe23a Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Fri, 27 May 2016 13:08:59 -0700 Subject: [PATCH] x86/entry: Get rid of two-phase syscall entry work I added two-phase syscall entry work back when the entry slow path was very slow. Nowadays, the entry slow path is fast and two-phase entry work serves no purpose. Remove it. Signed-off-by: Andy Lutomirski Signed-off-by: Kees Cook --- arch/x86/entry/common.c | 84 ++++------------------------------- arch/x86/include/asm/ptrace.h | 6 --- 2 files changed, 8 insertions(+), 82 deletions(-) diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index ec138e538c44..df56ca394877 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -64,20 +64,13 @@ 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) { + u32 arch = in_ia32_syscall() ? AUDIT_ARCH_I386 : AUDIT_ARCH_X86_64; + struct thread_info *ti = pt_regs_to_thread_info(regs); unsigned long ret = 0; u32 work; @@ -118,59 +111,9 @@ 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; - } -#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; + ret = __secure_computing(&sd); + if (ret == -1) + return ret; } #endif @@ -189,17 +132,6 @@ 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) diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h index 6271281f947d..2b5d686ea9f3 100644 --- a/arch/x86/include/asm/ptrace.h +++ b/arch/x86/include/asm/ptrace.h @@ -83,12 +83,6 @@ extern void send_sigtrap(struct task_struct *tsk, struct pt_regs *regs, int error_code, int si_code); -extern unsigned long syscall_trace_enter_phase1(struct pt_regs *, u32 arch); -extern long syscall_trace_enter_phase2(struct pt_regs *, u32 arch, - unsigned long phase1_result); - -extern long syscall_trace_enter(struct pt_regs *); - static inline unsigned long regs_return_value(struct pt_regs *regs) { return regs->ax; -- 2.20.1