[PATCH v11 9/9] x86: Disallow vsyscall emulation when CET is enabled
From: Yu-cheng Yu <hidden>
Date: 2020-08-25 00:31:07
Also in:
linux-arch, linux-doc, linux-mm, lkml
Subsystem:
the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
From: "H.J. Lu" <redacted> Emulation of the legacy vsyscall page is required by some programs built before 2013. Newer programs after 2013 don't use it. Disallow vsyscall emulation when Control-flow Enforcement (CET) is enabled to enhance security. Signed-off-by: H.J. Lu <redacted> Signed-off-by: Yu-cheng Yu <redacted> --- arch/x86/Kconfig | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 5bd6d6a10047..bbc68ecfae2b 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig@@ -1210,7 +1210,7 @@ config X86_ESPFIX64 config X86_VSYSCALL_EMULATION bool "Enable vsyscall emulation" if EXPERT default y - depends on X86_64 + depends on X86_64 && !X86_INTEL_CET help This enables emulation of the legacy vsyscall page. Disabling it is roughly equivalent to booting with vsyscall=none, except
@@ -1225,6 +1225,8 @@ config X86_VSYSCALL_EMULATION Disabling this option saves about 7K of kernel size and possibly 4K of additional runtime pagetable memory. + This option is disabled when Intel CET is enabled. + config X86_IOPL_IOPERM bool "IOPERM and IOPL Emulation" default y
@@ -2361,7 +2363,7 @@ config COMPAT_VDSO choice prompt "vsyscall table for legacy applications" - depends on X86_64 + depends on X86_64 && !X86_INTEL_CET default LEGACY_VSYSCALL_XONLY help Legacy user code that does not know how to find the vDSO expects
@@ -2378,6 +2380,8 @@ choice If unsure, select "Emulate execution only". + This option is not enabled when Intel CET is enabled. + config LEGACY_VSYSCALL_EMULATE bool "Full emulation" help
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2.21.0