From: Mauricio Faria de Oliveira Date: Fri, 30 Mar 2018 17:28:25 +0000 (-0300) Subject: powerpc/pseries: Restore default security feature flags on setup X-Git-Tag: Ubuntu-4.13.0-43.48~2 X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=c78497aedb186aeb7db6505eee98be2e30b40d69;p=mirror_ubuntu-artful-kernel.git powerpc/pseries: Restore default security feature flags on setup After migration the security feature flags might have changed (e.g., destination system with unpatched firmware), but some flags are not set/clear again in init_cpu_char_feature_flags() because it assumes the security flags to be the defaults. Additionally, if the H_GET_CPU_CHARACTERISTICS hypercall fails then init_cpu_char_feature_flags() does not run again, which potentially might leave the system in an insecure or sub-optimal configuration. So, just restore the security feature flags to the defaults assumed by init_cpu_char_feature_flags() so it can set/clear them correctly, and to ensure safe settings are in place in case the hypercall fail. Fixes: f636c14790ea ("powerpc/pseries: Set or clear security feature flags") Depends-on: 19887d6a28e2 ("powerpc: Move default security feature flags") Signed-off-by: Mauricio Faria de Oliveira Signed-off-by: Michael Ellerman (cherry picked from commit 6232774f1599028a15418179d17f7df47ede770a) CVE-2018-3639 (powerpc) Signed-off-by: Stefan Bader --- diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c index e6d707df7ecf..beb1f6fab44e 100644 --- a/arch/powerpc/platforms/pseries/setup.c +++ b/arch/powerpc/platforms/pseries/setup.c @@ -458,6 +458,10 @@ static void __init find_and_init_phbs(void) static void init_cpu_char_feature_flags(struct h_cpu_char_result *result) { + /* + * The features below are disabled by default, so we instead look to see + * if firmware has *enabled* them, and set them if so. + */ if (result->character & H_CPU_CHAR_SPEC_BAR_ORI31) security_ftr_set(SEC_FTR_SPEC_BAR_ORI31); @@ -497,6 +501,13 @@ static void pseries_setup_rfi_flush(void) bool enable; long rc; + /* + * Set features to the defaults assumed by init_cpu_char_feature_flags() + * so it can set/clear again any features that might have changed after + * migration, and in case the hypercall fails and it is not even called. + */ + powerpc_security_features = SEC_FTR_DEFAULT; + rc = plpar_get_cpu_characteristics(&result); if (rc == H_SUCCESS) init_cpu_char_feature_flags(&result);