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From: Kees Cook <keescook@chromium.org>
To: Borislav Petkov <bp@alien8.de>
Cc: Kees Cook <keescook@chromium.org>,
	Hector Marco-Gisbert <hecmargi@upv.es>,
	Jason Gunthorpe <jgg@mellanox.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Jason Gunthorpe <jgg@ziepe.ca>,
	Russell King <linux@armlinux.org.uk>,
	Will Deacon <will@kernel.org>, Jann Horn <jannh@google.com>,
	x86@kernel.org, linux-arm-kernel@lists.infradead.org,
	kernel-hardening@lists.openwall.com,
	linux-kernel@vger.kernel.org
Subject: [PATCH v5 6/6] arm64, elf: Disable automatic READ_IMPLIES_EXEC for 64-bit address spaces
Date: Thu, 26 Mar 2020 23:48:20 -0700	[thread overview]
Message-ID: <20200327064820.12602-7-keescook@chromium.org> (raw)
In-Reply-To: <20200327064820.12602-1-keescook@chromium.org>

With arm64 64-bit environments, there should never be a need for automatic
READ_IMPLIES_EXEC, as the architecture has always been execute-bit aware
(as in, the default memory protection should be NX unless a region
explicitly requests to be executable).

Suggested-by: Hector Marco-Gisbert <hecmargi@upv.es>
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
---
 arch/arm64/include/asm/elf.h | 4 ++--
 fs/compat_binfmt_elf.c       | 5 +++++
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h
index 0074e9fd6431..0e7df6f1eb7a 100644
--- a/arch/arm64/include/asm/elf.h
+++ b/arch/arm64/include/asm/elf.h
@@ -105,7 +105,7 @@
  *                CPU*: | arm32      | arm64      |
  * ELF:                 |            |            |
  * ---------------------|------------|------------|
- * missing PT_GNU_STACK | exec-all   | exec-all   |
+ * missing PT_GNU_STACK | exec-all   | exec-none  |
  * PT_GNU_STACK == RWX  | exec-stack | exec-stack |
  * PT_GNU_STACK == RW   | exec-none  | exec-none  |
  *
@@ -117,7 +117,7 @@
  *  *all arm64 CPUs support NX, so there is no "lacks NX" column.
  *
  */
-#define elf_read_implies_exec(ex, stk)	(stk == EXSTACK_DEFAULT)
+#define compat_elf_read_implies_exec(ex, stk)	(stk == EXSTACK_DEFAULT)
 
 #define CORE_DUMP_USE_REGSET
 #define ELF_EXEC_PAGESIZE	PAGE_SIZE
diff --git a/fs/compat_binfmt_elf.c b/fs/compat_binfmt_elf.c
index aaad4ca1217e..3068d57436b3 100644
--- a/fs/compat_binfmt_elf.c
+++ b/fs/compat_binfmt_elf.c
@@ -113,6 +113,11 @@
 #define	arch_setup_additional_pages compat_arch_setup_additional_pages
 #endif
 
+#ifdef	compat_elf_read_implies_exec
+#undef	elf_read_implies_exec
+#define	elf_read_implies_exec compat_elf_read_implies_exec
+#endif
+
 /*
  * Rename a few of the symbols that binfmt_elf.c will define.
  * These are all local so the names don't really matter, but it
-- 
2.20.1


WARNING: multiple messages have this Message-ID (diff)
From: Kees Cook <keescook@chromium.org>
To: Borislav Petkov <bp@alien8.de>
Cc: Kees Cook <keescook@chromium.org>, Jann Horn <jannh@google.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	x86@kernel.org, Hector Marco-Gisbert <hecmargi@upv.es>,
	Russell King <linux@armlinux.org.uk>,
	linux-kernel@vger.kernel.org, Jason Gunthorpe <jgg@ziepe.ca>,
	Jason Gunthorpe <jgg@mellanox.com>,
	kernel-hardening@lists.openwall.com,
	Will Deacon <will@kernel.org>,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH v5 6/6] arm64, elf: Disable automatic READ_IMPLIES_EXEC for 64-bit address spaces
Date: Thu, 26 Mar 2020 23:48:20 -0700	[thread overview]
Message-ID: <20200327064820.12602-7-keescook@chromium.org> (raw)
In-Reply-To: <20200327064820.12602-1-keescook@chromium.org>

With arm64 64-bit environments, there should never be a need for automatic
READ_IMPLIES_EXEC, as the architecture has always been execute-bit aware
(as in, the default memory protection should be NX unless a region
explicitly requests to be executable).

Suggested-by: Hector Marco-Gisbert <hecmargi@upv.es>
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
---
 arch/arm64/include/asm/elf.h | 4 ++--
 fs/compat_binfmt_elf.c       | 5 +++++
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h
index 0074e9fd6431..0e7df6f1eb7a 100644
--- a/arch/arm64/include/asm/elf.h
+++ b/arch/arm64/include/asm/elf.h
@@ -105,7 +105,7 @@
  *                CPU*: | arm32      | arm64      |
  * ELF:                 |            |            |
  * ---------------------|------------|------------|
- * missing PT_GNU_STACK | exec-all   | exec-all   |
+ * missing PT_GNU_STACK | exec-all   | exec-none  |
  * PT_GNU_STACK == RWX  | exec-stack | exec-stack |
  * PT_GNU_STACK == RW   | exec-none  | exec-none  |
  *
@@ -117,7 +117,7 @@
  *  *all arm64 CPUs support NX, so there is no "lacks NX" column.
  *
  */
-#define elf_read_implies_exec(ex, stk)	(stk == EXSTACK_DEFAULT)
+#define compat_elf_read_implies_exec(ex, stk)	(stk == EXSTACK_DEFAULT)
 
 #define CORE_DUMP_USE_REGSET
 #define ELF_EXEC_PAGESIZE	PAGE_SIZE
diff --git a/fs/compat_binfmt_elf.c b/fs/compat_binfmt_elf.c
index aaad4ca1217e..3068d57436b3 100644
--- a/fs/compat_binfmt_elf.c
+++ b/fs/compat_binfmt_elf.c
@@ -113,6 +113,11 @@
 #define	arch_setup_additional_pages compat_arch_setup_additional_pages
 #endif
 
+#ifdef	compat_elf_read_implies_exec
+#undef	elf_read_implies_exec
+#define	elf_read_implies_exec compat_elf_read_implies_exec
+#endif
+
 /*
  * Rename a few of the symbols that binfmt_elf.c will define.
  * These are all local so the names don't really matter, but it
-- 
2.20.1


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  parent reply	other threads:[~2020-03-27  6:48 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-27  6:48 [PATCH v5 0/6] binfmt_elf: Update READ_IMPLIES_EXEC logic for modern CPUs Kees Cook
2020-03-27  6:48 ` Kees Cook
2020-03-27  6:48 ` [PATCH v5 1/6] x86/elf: Add table to document READ_IMPLIES_EXEC Kees Cook
2020-03-27  6:48   ` Kees Cook
2020-04-20 20:03   ` [tip: core/core] " tip-bot2 for Kees Cook
2020-03-27  6:48 ` [PATCH v5 2/6] x86/elf: Split READ_IMPLIES_EXEC from executable PT_GNU_STACK Kees Cook
2020-03-27  6:48   ` Kees Cook
2020-04-20 20:03   ` [tip: core/core] " tip-bot2 for Kees Cook
2020-03-27  6:48 ` [PATCH v5 3/6] x86/elf: Disable automatic READ_IMPLIES_EXEC for 64-bit address spaces Kees Cook
2020-03-27  6:48   ` Kees Cook
2020-04-20 20:03   ` [tip: core/core] x86/elf: Disable automatic READ_IMPLIES_EXEC on 64-bit tip-bot2 for Kees Cook
2020-03-27  6:48 ` [PATCH v5 4/6] arm32/64, elf: Add tables to document READ_IMPLIES_EXEC Kees Cook
2020-03-27  6:48   ` Kees Cook
2020-04-20 20:03   ` [tip: core/core] arm32/64/elf: " tip-bot2 for Kees Cook
2020-03-27  6:48 ` [PATCH v5 5/6] arm32/64, elf: Split READ_IMPLIES_EXEC from executable PT_GNU_STACK Kees Cook
2020-03-27  6:48   ` Kees Cook
2020-04-20 20:03   ` [tip: core/core] arm32/64/elf: " tip-bot2 for Kees Cook
2020-03-27  6:48 ` Kees Cook [this message]
2020-03-27  6:48   ` [PATCH v5 6/6] arm64, elf: Disable automatic READ_IMPLIES_EXEC for 64-bit address spaces Kees Cook
2020-04-20 20:03   ` [tip: core/core] arm64/elf: " tip-bot2 for Kees Cook

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