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Message-Id: <1465506124-21866-4-git-send-email-keescook@chromium.org>
Date: Thu, 9 Jun 2016 14:01:53 -0700
From: Kees Cook <keescook@...omium.org>
To: linux-kernel@...r.kernel.org
Cc: Kees Cook <keescook@...omium.org>,
Andy Lutomirski <luto@...nel.org>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Catalin Marinas <catalin.marinas@....com>,
Chris Metcalf <cmetcalf@...lanox.com>,
Heiko Carstens <heiko.carstens@...ibm.com>,
Helge Deller <deller@....de>,
"James E.J. Bottomley" <jejb@...isc-linux.org>,
James Hogan <james.hogan@...tec.com>,
Jeff Dike <jdike@...toit.com>, linux-arch@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, linux-mips@...ux-mips.org,
linux-parisc@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
linux-s390@...r.kernel.org, "Maciej W. Rozycki" <macro@...tec.com>,
Mark Rutland <mark.rutland@....com>,
Martin Schwidefsky <schwidefsky@...ibm.com>,
Michael Ellerman <mpe@...erman.id.au>,
Paul Mackerras <paulus@...ba.org>,
Ralf Baechle <ralf@...ux-mips.org>,
Richard Weinberger <richard@....at>,
Russell King <linux@...linux.org.uk>,
user-mode-linux-devel@...ts.sourceforge.net,
Will Deacon <will.deacon@....com>, x86@...nel.org
Subject: [PATCH 03/14] x86/entry: Get rid of two-phase syscall entry work
From: Andy Lutomirski <luto@...nel.org>
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 <luto@...nel.org>
Signed-off-by: Kees Cook <keescook@...omium.org>
---
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;
--
2.7.4
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