On Wed, Mar 11, 2020 at 08:44:46PM +0100, Borislav Petkov wrote:

Ozenn Mon, Feb 24, 2020 at 09:13:02PM -0800, Kees Cook wrote:

quoted

Add a table to document the current behavior of READ_IMPLIES_EXEC in
preparation for changing the behavior.

Signed-off-by: Kees Cook <redacted>
Reviewed-by: Jason Gunthorpe <redacted>
---
 arch/x86/include/asm/elf.h | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
index 69c0f892e310..733f69c2b053 100644
--- a/arch/x86/include/asm/elf.h
+++ b/arch/x86/include/asm/elf.h

@@ -281,6 +281,25 @@ extern u32 elf_hwcap2;
 /*
  * An executable for which elf_read_implies_exec() returns TRUE will
  * have the READ_IMPLIES_EXEC personality flag set automatically.
+ *
+ * The decision process for determining the results are:
+ *
+ *              CPU: | lacks NX*  | has NX, ia32     | has NX, x86_64 |
+ * ELF:              |            |                  |                |
+ * -------------------------------|------------------|----------------|
+ * missing GNU_STACK | exec-all   | exec-all         | exec-all       |
+ * GNU_STACK == RWX  | exec-all   | exec-all         | exec-all       |
+ * GNU_STACK == RW   | exec-none  | exec-none        | exec-none      |

In all those tables, you wanna do:

s/GNU_STACK/PT_GNU_STACK/g

so that it is clear what this define is.

Fair enough. :) I think I was trying to save 3 characters from earlier
tables that were wider. I'll send a v5.

Thanks!

-Kees

-- 
Kees Cook

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