From f21b53b20c754021935ea43364dbf53778eeba32 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Thu, 3 May 2018 14:37:54 -0700 Subject: x86/speculation: Make "seccomp" the default mode for Speculative Store Bypass Unless explicitly opted out of, anything running under seccomp will have SSB mitigations enabled. Choosing the "prctl" mode will disable this. [ tglx: Adjusted it to the new arch_seccomp_spec_mitigate() mechanism ] Signed-off-by: Kees Cook Signed-off-by: Thomas Gleixner --- Documentation/admin-guide/kernel-parameters.txt | 26 ++++++++++++++++--------- 1 file changed, 17 insertions(+), 9 deletions(-) (limited to 'Documentation/admin-guide') diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index a8d2ae1e335b..f2040d46f095 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -4049,19 +4049,27 @@ This parameter controls whether the Speculative Store Bypass optimization is used. - on - Unconditionally disable Speculative Store Bypass - off - Unconditionally enable Speculative Store Bypass - auto - Kernel detects whether the CPU model contains an - implementation of Speculative Store Bypass and - picks the most appropriate mitigation. - prctl - Control Speculative Store Bypass per thread - via prctl. Speculative Store Bypass is enabled - for a process by default. The state of the control - is inherited on fork. + on - Unconditionally disable Speculative Store Bypass + off - Unconditionally enable Speculative Store Bypass + auto - Kernel detects whether the CPU model contains an + implementation of Speculative Store Bypass and + picks the most appropriate mitigation. If the + CPU is not vulnerable, "off" is selected. If the + CPU is vulnerable the default mitigation is + architecture and Kconfig dependent. See below. + prctl - Control Speculative Store Bypass per thread + via prctl. Speculative Store Bypass is enabled + for a process by default. The state of the control + is inherited on fork. + seccomp - Same as "prctl" above, but all seccomp threads + will disable SSB unless they explicitly opt out. Not specifying this option is equivalent to spec_store_bypass_disable=auto. + Default mitigations: + X86: If CONFIG_SECCOMP=y "seccomp", otherwise "prctl" + spia_io_base= [HW,MTD] spia_fio_base= spia_pedr= -- cgit v1.2.3