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From: Kees Cook <keescook@chromium.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: Kees Cook <keescook@chromium.org>,
	Hector Marco-Gisbert <hecmargi@upv.es>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Jason Gunthorpe <jgg@mellanox.com>, Jann Horn <jannh@google.com>,
	Russell King <linux@armlinux.org.uk>,
	x86@kernel.org, kernel-hardening@lists.openwall.com,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org
Subject: [PATCH v3 6/7] arm64, elf: Disable automatic READ_IMPLIES_EXEC for 64-bit address spaces
Date: Mon, 10 Feb 2020 11:30:48 -0800
Message-ID: <20200210193049.64362-7-keescook@chromium.org> (raw)
In-Reply-To: <20200210193049.64362-1-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>
---
 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 03ada29984a7..ea9221ed68a1 100644
--- a/arch/arm64/include/asm/elf.h
+++ b/arch/arm64/include/asm/elf.h
@@ -105,7 +105,7 @@
  *             CPU*: | arm32      | arm64      |
  * ELF:              |            |            |
  * -------------------------------|------------|
- * missing GNU_STACK | exec-all   | exec-all   |
+ * missing GNU_STACK | exec-all   | exec-none  |
  * GNU_STACK == RWX  | exec-stack | exec-stack |
  * 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


  parent reply index

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-10 19:30 [PATCH v3 0/7] binfmt_elf: Update READ_IMPLIES_EXEC logic for modern CPUs Kees Cook
2020-02-10 19:30 ` [PATCH v3 1/7] x86/elf: Add table to document READ_IMPLIES_EXEC Kees Cook
2020-02-10 19:30 ` [PATCH v3 2/7] x86/elf: Split READ_IMPLIES_EXEC from executable GNU_STACK Kees Cook
2020-02-10 19:30 ` [PATCH v3 3/7] x86/elf: Disable automatic READ_IMPLIES_EXEC for 64-bit address spaces Kees Cook
2020-02-10 19:30 ` [PATCH v3 4/7] arm32/64, elf: Add tables to document READ_IMPLIES_EXEC Kees Cook
2020-02-12  9:27   ` Catalin Marinas
2020-02-10 19:30 ` [PATCH v3 5/7] arm32/64, elf: Split READ_IMPLIES_EXEC from executable GNU_STACK Kees Cook
2020-02-12  9:27   ` Catalin Marinas
2020-02-10 19:30 ` Kees Cook [this message]
2020-02-12  9:28   ` [PATCH v3 6/7] arm64, elf: Disable automatic READ_IMPLIES_EXEC for 64-bit address spaces Catalin Marinas
2020-02-10 19:30 ` [PATCH v3 7/7] selftests/exec: Add READ_IMPLIES_EXEC tests Kees Cook
2020-02-11 18:11   ` shuah
2020-02-11 19:25     ` Kees Cook
2020-02-11 21:06       ` shuah
2020-02-11 23:54         ` Kees Cook
2020-02-12  0:02           ` shuah
2020-02-11 17:17 ` [PATCH v3 0/7] binfmt_elf: Update READ_IMPLIES_EXEC logic for modern CPUs Jason Gunthorpe

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