Messages in this thread Patch in this message | | | From | Nikolay Borisov <> | Subject | [PATCH 1/3] x86: Introduce ia32_disabled boot parameter | Date | Wed, 7 Jun 2023 10:29:34 +0300 |
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Distributions would like to reduce their attack surface as much as possible but at the same time they have to cater to a wide variety of legacy software. One such avenue where distros have to strike a balance is the support for 32bit syscalls on a 64bit kernel. Ideally we'd have the ability to disable the the compat support at boot time. This would allow the decision whether it should be disabled/enabled can be delegated to system administrators.
This patch simply introduces ia32_disable boot parameter which aims at disabling 32 bit process support even if CONFIG_IA32_EMULATION has been selected at build time.
Signed-off-by: Nikolay Borisov <nik.borisov@suse.com> --- arch/x86/entry/common.c | 12 ++++++++++++ arch/x86/include/asm/traps.h | 4 ++++ 2 files changed, 16 insertions(+)
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index 6c2826417b33..817518768ba2 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -19,6 +19,7 @@ #include <linux/nospec.h> #include <linux/syscalls.h> #include <linux/uaccess.h> +#include <linux/init.h> #ifdef CONFIG_XEN_PV #include <xen/xen-ops.h> @@ -96,6 +97,17 @@ static __always_inline int syscall_32_enter(struct pt_regs *regs) return (int)regs->orig_ax; } +#ifdef CONFIG_IA32_EMULATION +bool ia32_disabled = false; + +static int ia32_disabled_cmdline(char *arg) +{ + ia32_disabled = true; + return 1; +} +__setup("ia32_disabled", ia32_disabled_cmdline); +#endif + /* * Invoke a 32-bit syscall. Called with IRQs on in CONTEXT_KERNEL. */ diff --git a/arch/x86/include/asm/traps.h b/arch/x86/include/asm/traps.h index 47ecfff2c83d..dd93aac3718b 100644 --- a/arch/x86/include/asm/traps.h +++ b/arch/x86/include/asm/traps.h @@ -20,6 +20,10 @@ asmlinkage __visible noinstr struct pt_regs *vc_switch_off_ist(struct pt_regs *e extern bool ibt_selftest(void); +#ifdef CONFIG_IA32_EMULATION +extern bool ia32_disabled; +#endif + #ifdef CONFIG_X86_F00F_BUG /* For handling the FOOF bug */ void handle_invalid_op(struct pt_regs *regs); -- 2.34.1
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