linux-kernel - [PATCH v2 4/4] x86: Disable laoding 32bit processes if ia32

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Date:   Fri,  9 Jun 2023 14:13:11 +0300
From:   Nikolay Borisov <nik.borisov@...e.com>
To:     x86@...nel.org
Cc:     linux-kernel@...r.kernel.org, mhocko@...e.com, jslaby@...e.cz,
        Nikolay Borisov <nik.borisov@...e.com>
Subject: [PATCH v2 4/4] x86: Disable laoding 32bit processes if ia32_disabled is true

In addition to disabling 32bit syscall interface let's also disable the
ability to load 32bit compat processes.

Signed-off-by: Nikolay Borisov <nik.borisov@...e.com>
---
 arch/x86/include/asm/elf.h | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
index 18fd06f7936a..0fa49388ff16 100644
--- a/arch/x86/include/asm/elf.h
+++ b/arch/x86/include/asm/elf.h
@@ -148,9 +148,16 @@ do {						\
 #define elf_check_arch(x)			\
 	((x)->e_machine == EM_X86_64)
 
+#ifdef CONFIG_IA32_EMULATION
+extern bool ia32_disabled;
 #define compat_elf_check_arch(x)					\
-	(elf_check_arch_ia32(x) ||					\
+	((elf_check_arch_ia32(x) && !ia32_disabled) ||			\
 	 (IS_ENABLED(CONFIG_X86_X32_ABI) && (x)->e_machine == EM_X86_64))
+#else
+#define compat_elf_check_arch(x)					\
+	(elf_check_arch_ia32(x) ||			\
+	 (IS_ENABLED(CONFIG_X86_X32_ABI) && (x)->e_machine == EM_X86_64))
+#endif
 
 static inline void elf_common_init(struct thread_struct *t,
 				   struct pt_regs *regs, const u16 ds)
-- 
2.34.1