linux-hardening - [PATCH 1/3] x86/uaccess: Move nmi_uaccess

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Date:   Fri, 16 Sep 2022 06:59:53 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     Kees Cook <keescook@...omium.org>,
        Uladzislau Rezki <urezki@...il.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, linux-perf-users@...r.kernel.org,
        bpf@...r.kernel.org, Yu Zhao <yuzhao@...gle.com>, dev@...-flo.net,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-hardening@...r.kernel.org, linux-arch@...r.kernel.org
Subject: [PATCH 1/3] x86/uaccess: Move nmi_uaccess_okay() into uaccess.h

In preparation for inlining copy_from_user_in_nmi(), move the
nmi_uaccess_okay() declaration into uaccess.h, which makes a bit more
sense anyway. Additionally update all callers to remove the no longer
needed tlbflush.h include, which was only for the declaration of
nmi_uaccess_okay().

Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: x86@...nel.org
Cc: linux-perf-users@...r.kernel.org
Cc: bpf@...r.kernel.org
Cc: Matthew Wilcox <willy@...radead.org>
Cc: Yu Zhao <yuzhao@...gle.com>
Cc: dev@...-flo.net
Signed-off-by: Kees Cook <keescook@...omium.org>
---
 arch/x86/events/core.c          | 1 -
 arch/x86/include/asm/tlbflush.h | 3 ---
 arch/x86/include/asm/uaccess.h  | 3 +++
 arch/x86/lib/usercopy.c         | 2 --
 include/asm-generic/tlb.h       | 9 ---------
 include/linux/uaccess.h         | 9 +++++++++
 kernel/trace/bpf_trace.c        | 2 --
 7 files changed, 12 insertions(+), 17 deletions(-)

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index f969410d0c90..3e2bb6324ca3 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -36,7 +36,6 @@
 #include <asm/smp.h>
 #include <asm/alternative.h>
 #include <asm/mmu_context.h>
-#include <asm/tlbflush.h>
 #include <asm/timer.h>
 #include <asm/desc.h>
 #include <asm/ldt.h>
diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h
index cda3118f3b27..233818bb72c6 100644
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -157,9 +157,6 @@ struct tlb_state_shared {
 };
 DECLARE_PER_CPU_SHARED_ALIGNED(struct tlb_state_shared, cpu_tlbstate_shared);
 
-bool nmi_uaccess_okay(void);
-#define nmi_uaccess_okay nmi_uaccess_okay
-
 /* Initialize cr4 shadow for this CPU. */
 static inline void cr4_init_shadow(void)
 {
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 913e593a3b45..e9390eea861b 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -20,6 +20,9 @@ static inline bool pagefault_disabled(void);
 # define WARN_ON_IN_IRQ()
 #endif
 
+bool nmi_uaccess_okay(void);
+#define nmi_uaccess_okay nmi_uaccess_okay
+
 /**
  * access_ok - Checks if a user space pointer is valid
  * @addr: User space pointer to start of block to check
diff --git a/arch/x86/lib/usercopy.c b/arch/x86/lib/usercopy.c
index ad0139d25401..959489f2f814 100644
--- a/arch/x86/lib/usercopy.c
+++ b/arch/x86/lib/usercopy.c
@@ -7,8 +7,6 @@
 #include <linux/uaccess.h>
 #include <linux/export.h>
 
-#include <asm/tlbflush.h>
-
 /**
  * copy_from_user_nmi - NMI safe copy from user
  * @to:		Pointer to the destination buffer
diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
index 492dce43236e..14efd74f3e70 100644
--- a/include/asm-generic/tlb.h
+++ b/include/asm-generic/tlb.h
@@ -17,15 +17,6 @@
 #include <asm/tlbflush.h>
 #include <asm/cacheflush.h>
 
-/*
- * Blindly accessing user memory from NMI context can be dangerous
- * if we're in the middle of switching the current user task or switching
- * the loaded mm.
- */
-#ifndef nmi_uaccess_okay
-# define nmi_uaccess_okay() true
-#endif
-
 #ifdef CONFIG_MMU
 
 /*
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index 47e5d374c7eb..065e121d2a86 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -10,6 +10,15 @@
 
 #include <asm/uaccess.h>
 
+/*
+ * Blindly accessing user memory from NMI context can be dangerous
+ * if we're in the middle of switching the current user task or switching
+ * the loaded mm.
+ */
+#ifndef nmi_uaccess_okay
+# define nmi_uaccess_okay() true
+#endif
+
 /*
  * Architectures should provide two primitives (raw_copy_{to,from}_user())
  * and get rid of their private instances of copy_{to,from}_user() and
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 68e5cdd24cef..0fd185c3d174 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -26,8 +26,6 @@
 #include <uapi/linux/bpf.h>
 #include <uapi/linux/btf.h>
 
-#include <asm/tlb.h>
-
 #include "trace_probe.h"
 #include "trace.h"
 
-- 
2.34.1