diff options
Diffstat (limited to 'arch/x86/kernel/cpu/bugs.c')
| -rw-r--r-- | arch/x86/kernel/cpu/bugs.c | 689 |
1 files changed, 371 insertions, 318 deletions
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index af838b8d845c..6a526ae1fe99 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -96,6 +96,9 @@ static void __init its_update_mitigation(void); static void __init its_apply_mitigation(void); static void __init tsa_select_mitigation(void); static void __init tsa_apply_mitigation(void); +static void __init vmscape_select_mitigation(void); +static void __init vmscape_update_mitigation(void); +static void __init vmscape_apply_mitigation(void); /* The base value of the SPEC_CTRL MSR without task-specific bits set */ u64 x86_spec_ctrl_base; @@ -105,6 +108,14 @@ EXPORT_SYMBOL_GPL(x86_spec_ctrl_base); DEFINE_PER_CPU(u64, x86_spec_ctrl_current); EXPORT_PER_CPU_SYMBOL_GPL(x86_spec_ctrl_current); +/* + * Set when the CPU has run a potentially malicious guest. An IBPB will + * be needed to before running userspace. That IBPB will flush the branch + * predictor content. + */ +DEFINE_PER_CPU(bool, x86_ibpb_exit_to_user); +EXPORT_PER_CPU_SYMBOL_GPL(x86_ibpb_exit_to_user); + u64 x86_pred_cmd __ro_after_init = PRED_CMD_IBPB; static u64 __ro_after_init x86_arch_cap_msr; @@ -262,6 +273,7 @@ void __init cpu_select_mitigations(void) its_select_mitigation(); bhi_select_mitigation(); tsa_select_mitigation(); + vmscape_select_mitigation(); /* * After mitigations are selected, some may need to update their @@ -293,6 +305,7 @@ void __init cpu_select_mitigations(void) bhi_update_mitigation(); /* srso_update_mitigation() depends on retbleed_update_mitigation(). */ srso_update_mitigation(); + vmscape_update_mitigation(); spectre_v1_apply_mitigation(); spectre_v2_apply_mitigation(); @@ -310,6 +323,7 @@ void __init cpu_select_mitigations(void) its_apply_mitigation(); bhi_apply_mitigation(); tsa_apply_mitigation(); + vmscape_apply_mitigation(); } /* @@ -420,6 +434,9 @@ static bool __init should_mitigate_vuln(unsigned int bug) case X86_BUG_SPEC_STORE_BYPASS: return cpu_attack_vector_mitigated(CPU_MITIGATE_USER_USER); + case X86_BUG_VMSCAPE: + return cpu_attack_vector_mitigated(CPU_MITIGATE_GUEST_HOST); + default: WARN(1, "Unknown bug %x\n", bug); return false; @@ -670,8 +687,7 @@ static const char * const mmio_strings[] = { static void __init mmio_select_mitigation(void) { - if (!boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA) || - cpu_mitigations_off()) { + if (!boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA)) { mmio_mitigation = MMIO_MITIGATION_OFF; return; } @@ -1446,8 +1462,10 @@ static void __init retbleed_update_mitigation(void) retbleed_mitigation = RETBLEED_MITIGATION_EIBRS; break; default: - if (retbleed_mitigation != RETBLEED_MITIGATION_STUFF) + if (retbleed_mitigation != RETBLEED_MITIGATION_STUFF) { pr_err(RETBLEED_INTEL_MSG); + retbleed_mitigation = RETBLEED_MITIGATION_NONE; + } } } @@ -1828,9 +1846,10 @@ enum spectre_v2_mitigation_cmd { SPECTRE_V2_CMD_IBRS, }; -static enum spectre_v2_mitigation_cmd spectre_v2_cmd __ro_after_init = SPECTRE_V2_CMD_AUTO; +static enum spectre_v2_mitigation_cmd spectre_v2_cmd __ro_after_init = + IS_ENABLED(CONFIG_MITIGATION_SPECTRE_V2) ? SPECTRE_V2_CMD_AUTO : SPECTRE_V2_CMD_NONE; -enum spectre_v2_user_cmd { +enum spectre_v2_user_mitigation_cmd { SPECTRE_V2_USER_CMD_NONE, SPECTRE_V2_USER_CMD_AUTO, SPECTRE_V2_USER_CMD_FORCE, @@ -1840,6 +1859,9 @@ enum spectre_v2_user_cmd { SPECTRE_V2_USER_CMD_SECCOMP_IBPB, }; +static enum spectre_v2_user_mitigation_cmd spectre_v2_user_cmd __ro_after_init = + IS_ENABLED(CONFIG_MITIGATION_SPECTRE_V2) ? SPECTRE_V2_USER_CMD_AUTO : SPECTRE_V2_USER_CMD_NONE; + static const char * const spectre_v2_user_strings[] = { [SPECTRE_V2_USER_NONE] = "User space: Vulnerable", [SPECTRE_V2_USER_STRICT] = "User space: Mitigation: STIBP protection", @@ -1848,50 +1870,31 @@ static const char * const spectre_v2_user_strings[] = { [SPECTRE_V2_USER_SECCOMP] = "User space: Mitigation: STIBP via seccomp and prctl", }; -static const struct { - const char *option; - enum spectre_v2_user_cmd cmd; - bool secure; -} v2_user_options[] __initconst = { - { "auto", SPECTRE_V2_USER_CMD_AUTO, false }, - { "off", SPECTRE_V2_USER_CMD_NONE, false }, - { "on", SPECTRE_V2_USER_CMD_FORCE, true }, - { "prctl", SPECTRE_V2_USER_CMD_PRCTL, false }, - { "prctl,ibpb", SPECTRE_V2_USER_CMD_PRCTL_IBPB, false }, - { "seccomp", SPECTRE_V2_USER_CMD_SECCOMP, false }, - { "seccomp,ibpb", SPECTRE_V2_USER_CMD_SECCOMP_IBPB, false }, -}; - -static void __init spec_v2_user_print_cond(const char *reason, bool secure) +static int __init spectre_v2_user_parse_cmdline(char *str) { - if (boot_cpu_has_bug(X86_BUG_SPECTRE_V2) != secure) - pr_info("spectre_v2_user=%s forced on command line.\n", reason); -} - -static enum spectre_v2_user_cmd __init spectre_v2_parse_user_cmdline(void) -{ - char arg[20]; - int ret, i; - - if (!IS_ENABLED(CONFIG_MITIGATION_SPECTRE_V2)) - return SPECTRE_V2_USER_CMD_NONE; - - ret = cmdline_find_option(boot_command_line, "spectre_v2_user", - arg, sizeof(arg)); - if (ret < 0) - return SPECTRE_V2_USER_CMD_AUTO; + if (!str) + return -EINVAL; - for (i = 0; i < ARRAY_SIZE(v2_user_options); i++) { - if (match_option(arg, ret, v2_user_options[i].option)) { - spec_v2_user_print_cond(v2_user_options[i].option, - v2_user_options[i].secure); - return v2_user_options[i].cmd; - } - } + if (!strcmp(str, "auto")) + spectre_v2_user_cmd = SPECTRE_V2_USER_CMD_AUTO; + else if (!strcmp(str, "off")) + spectre_v2_user_cmd = SPECTRE_V2_USER_CMD_NONE; + else if (!strcmp(str, "on")) + spectre_v2_user_cmd = SPECTRE_V2_USER_CMD_FORCE; + else if (!strcmp(str, "prctl")) + spectre_v2_user_cmd = SPECTRE_V2_USER_CMD_PRCTL; + else if (!strcmp(str, "prctl,ibpb")) + spectre_v2_user_cmd = SPECTRE_V2_USER_CMD_PRCTL_IBPB; + else if (!strcmp(str, "seccomp")) + spectre_v2_user_cmd = SPECTRE_V2_USER_CMD_SECCOMP; + else if (!strcmp(str, "seccomp,ibpb")) + spectre_v2_user_cmd = SPECTRE_V2_USER_CMD_SECCOMP_IBPB; + else + pr_err("Ignoring unknown spectre_v2_user option (%s).", str); - pr_err("Unknown user space protection option (%s). Switching to default\n", arg); - return SPECTRE_V2_USER_CMD_AUTO; + return 0; } +early_param("spectre_v2_user", spectre_v2_user_parse_cmdline); static inline bool spectre_v2_in_ibrs_mode(enum spectre_v2_mitigation mode) { @@ -1903,7 +1906,7 @@ static void __init spectre_v2_user_select_mitigation(void) if (!boot_cpu_has(X86_FEATURE_IBPB) && !boot_cpu_has(X86_FEATURE_STIBP)) return; - switch (spectre_v2_parse_user_cmdline()) { + switch (spectre_v2_user_cmd) { case SPECTRE_V2_USER_CMD_NONE: return; case SPECTRE_V2_USER_CMD_FORCE: @@ -2031,119 +2034,61 @@ static void __init spectre_v2_user_apply_mitigation(void) static const char * const spectre_v2_strings[] = { [SPECTRE_V2_NONE] = "Vulnerable", [SPECTRE_V2_RETPOLINE] = "Mitigation: Retpolines", - [SPECTRE_V2_LFENCE] = "Mitigation: LFENCE", + [SPECTRE_V2_LFENCE] = "Vulnerable: LFENCE", [SPECTRE_V2_EIBRS] = "Mitigation: Enhanced / Automatic IBRS", [SPECTRE_V2_EIBRS_LFENCE] = "Mitigation: Enhanced / Automatic IBRS + LFENCE", [SPECTRE_V2_EIBRS_RETPOLINE] = "Mitigation: Enhanced / Automatic IBRS + Retpolines", [SPECTRE_V2_IBRS] = "Mitigation: IBRS", }; -static const struct { - const char *option; - enum spectre_v2_mitigation_cmd cmd; - bool secure; -} mitigation_options[] __initconst = { - { "off", SPECTRE_V2_CMD_NONE, false }, - { "on", SPECTRE_V2_CMD_FORCE, true }, - { "retpoline", SPECTRE_V2_CMD_RETPOLINE, false }, - { "retpoline,amd", SPECTRE_V2_CMD_RETPOLINE_LFENCE, false }, - { "retpoline,lfence", SPECTRE_V2_CMD_RETPOLINE_LFENCE, false }, - { "retpoline,generic", SPECTRE_V2_CMD_RETPOLINE_GENERIC, false }, - { "eibrs", SPECTRE_V2_CMD_EIBRS, false }, - { "eibrs,lfence", SPECTRE_V2_CMD_EIBRS_LFENCE, false }, - { "eibrs,retpoline", SPECTRE_V2_CMD_EIBRS_RETPOLINE, false }, - { "auto", SPECTRE_V2_CMD_AUTO, false }, - { "ibrs", SPECTRE_V2_CMD_IBRS, false }, -}; +static bool nospectre_v2 __ro_after_init; -static void __init spec_v2_print_cond(const char *reason, bool secure) +static int __init nospectre_v2_parse_cmdline(char *str) { - if (boot_cpu_has_bug(X86_BUG_SPECTRE_V2) != secure) - pr_info("%s selected on command line.\n", reason); + nospectre_v2 = true; + spectre_v2_cmd = SPECTRE_V2_CMD_NONE; + return 0; } +early_param("nospectre_v2", nospectre_v2_parse_cmdline); -static enum spectre_v2_mitigation_cmd __init spectre_v2_parse_cmdline(void) +static int __init spectre_v2_parse_cmdline(char *str) { - enum spectre_v2_mitigation_cmd cmd; - char arg[20]; - int ret, i; - - cmd = IS_ENABLED(CONFIG_MITIGATION_SPECTRE_V2) ? SPECTRE_V2_CMD_AUTO : SPECTRE_V2_CMD_NONE; - if (cmdline_find_option_bool(boot_command_line, "nospectre_v2")) - return SPECTRE_V2_CMD_NONE; - - ret = cmdline_find_option(boot_command_line, "spectre_v2", arg, sizeof(arg)); - if (ret < 0) - return cmd; - - for (i = 0; i < ARRAY_SIZE(mitigation_options); i++) { - if (!match_option(arg, ret, mitigation_options[i].option)) - continue; - cmd = mitigation_options[i].cmd; - break; - } - - if (i >= ARRAY_SIZE(mitigation_options)) { - pr_err("unknown option (%s). Switching to default mode\n", arg); - return cmd; - } - - if ((cmd == SPECTRE_V2_CMD_RETPOLINE || - cmd == SPECTRE_V2_CMD_RETPOLINE_LFENCE || - cmd == SPECTRE_V2_CMD_RETPOLINE_GENERIC || - cmd == SPECTRE_V2_CMD_EIBRS_LFENCE || - cmd == SPECTRE_V2_CMD_EIBRS_RETPOLINE) && - !IS_ENABLED(CONFIG_MITIGATION_RETPOLINE)) { - pr_err("%s selected but not compiled in. Switching to AUTO select\n", - mitigation_options[i].option); - return SPECTRE_V2_CMD_AUTO; - } - - if ((cmd == SPECTRE_V2_CMD_EIBRS || - cmd == SPECTRE_V2_CMD_EIBRS_LFENCE || - cmd == SPECTRE_V2_CMD_EIBRS_RETPOLINE) && - !boot_cpu_has(X86_FEATURE_IBRS_ENHANCED)) { - pr_err("%s selected but CPU doesn't have Enhanced or Automatic IBRS. Switching to AUTO select\n", - mitigation_options[i].option); - return SPECTRE_V2_CMD_AUTO; - } - - if ((cmd == SPECTRE_V2_CMD_RETPOLINE_LFENCE || - cmd == SPECTRE_V2_CMD_EIBRS_LFENCE) && - !boot_cpu_has(X86_FEATURE_LFENCE_RDTSC)) { - pr_err("%s selected, but CPU doesn't have a serializing LFENCE. Switching to AUTO select\n", - mitigation_options[i].option); - return SPECTRE_V2_CMD_AUTO; - } - - if (cmd == SPECTRE_V2_CMD_IBRS && !IS_ENABLED(CONFIG_MITIGATION_IBRS_ENTRY)) { - pr_err("%s selected but not compiled in. Switching to AUTO select\n", - mitigation_options[i].option); - return SPECTRE_V2_CMD_AUTO; - } - - if (cmd == SPECTRE_V2_CMD_IBRS && boot_cpu_data.x86_vendor != X86_VENDOR_INTEL) { - pr_err("%s selected but not Intel CPU. Switching to AUTO select\n", - mitigation_options[i].option); - return SPECTRE_V2_CMD_AUTO; - } + if (!str) + return -EINVAL; - if (cmd == SPECTRE_V2_CMD_IBRS && !boot_cpu_has(X86_FEATURE_IBRS)) { - pr_err("%s selected but CPU doesn't have IBRS. Switching to AUTO select\n", - mitigation_options[i].option); - return SPECTRE_V2_CMD_AUTO; - } + if (nospectre_v2) + return 0; - if (cmd == SPECTRE_V2_CMD_IBRS && cpu_feature_enabled(X86_FEATURE_XENPV)) { - pr_err("%s selected but running as XenPV guest. Switching to AUTO select\n", - mitigation_options[i].option); - return SPECTRE_V2_CMD_AUTO; + if (!strcmp(str, "off")) { + spectre_v2_cmd = SPECTRE_V2_CMD_NONE; + } else if (!strcmp(str, "on")) { + spectre_v2_cmd = SPECTRE_V2_CMD_FORCE; + setup_force_cpu_bug(X86_BUG_SPECTRE_V2); + setup_force_cpu_bug(X86_BUG_SPECTRE_V2_USER); + } else if (!strcmp(str, "retpoline")) { + spectre_v2_cmd = SPECTRE_V2_CMD_RETPOLINE; + } else if (!strcmp(str, "retpoline,amd") || + !strcmp(str, "retpoline,lfence")) { + spectre_v2_cmd = SPECTRE_V2_CMD_RETPOLINE_LFENCE; + } else if (!strcmp(str, "retpoline,generic")) { + spectre_v2_cmd = SPECTRE_V2_CMD_RETPOLINE_GENERIC; + } else if (!strcmp(str, "eibrs")) { + spectre_v2_cmd = SPECTRE_V2_CMD_EIBRS; + } else if (!strcmp(str, "eibrs,lfence")) { + spectre_v2_cmd = SPECTRE_V2_CMD_EIBRS_LFENCE; + } else if (!strcmp(str, "eibrs,retpoline")) { + spectre_v2_cmd = SPECTRE_V2_CMD_EIBRS_RETPOLINE; + } else if (!strcmp(str, "auto")) { + spectre_v2_cmd = SPECTRE_V2_CMD_AUTO; + } else if (!strcmp(str, "ibrs")) { + spectre_v2_cmd = SPECTRE_V2_CMD_IBRS; + } else { + pr_err("Ignoring unknown spectre_v2 option (%s).", str); } - spec_v2_print_cond(mitigation_options[i].option, - mitigation_options[i].secure); - return cmd; + return 0; } +early_param("spectre_v2", spectre_v2_parse_cmdline); static enum spectre_v2_mitigation __init spectre_v2_select_retpoline(void) { @@ -2292,10 +2237,6 @@ static void __init bhi_update_mitigation(void) { if (spectre_v2_cmd == SPECTRE_V2_CMD_NONE) bhi_mitigation = BHI_MITIGATION_OFF; - - if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2) && - spectre_v2_cmd == SPECTRE_V2_CMD_AUTO) - bhi_mitigation = BHI_MITIGATION_OFF; } static void __init bhi_apply_mitigation(void) @@ -2331,11 +2272,55 @@ static void __init bhi_apply_mitigation(void) static void __init spectre_v2_select_mitigation(void) { - spectre_v2_cmd = spectre_v2_parse_cmdline(); + if ((spectre_v2_cmd == SPECTRE_V2_CMD_RETPOLINE || + spectre_v2_cmd == SPECTRE_V2_CMD_RETPOLINE_LFENCE || + spectre_v2_cmd == SPECTRE_V2_CMD_RETPOLINE_GENERIC || + spectre_v2_cmd == SPECTRE_V2_CMD_EIBRS_LFENCE || + spectre_v2_cmd == SPECTRE_V2_CMD_EIBRS_RETPOLINE) && + !IS_ENABLED(CONFIG_MITIGATION_RETPOLINE)) { + pr_err("RETPOLINE selected but not compiled in. Switching to AUTO select\n"); + spectre_v2_cmd = SPECTRE_V2_CMD_AUTO; + } + + if ((spectre_v2_cmd == SPECTRE_V2_CMD_EIBRS || + spectre_v2_cmd == SPECTRE_V2_CMD_EIBRS_LFENCE || + spectre_v2_cmd == SPECTRE_V2_CMD_EIBRS_RETPOLINE) && + !boot_cpu_has(X86_FEATURE_IBRS_ENHANCED)) { + pr_err("EIBRS selected but CPU doesn't have Enhanced or Automatic IBRS. Switching to AUTO select\n"); + spectre_v2_cmd = SPECTRE_V2_CMD_AUTO; + } + + if ((spectre_v2_cmd == SPECTRE_V2_CMD_RETPOLINE_LFENCE || + spectre_v2_cmd == SPECTRE_V2_CMD_EIBRS_LFENCE) && + !boot_cpu_has(X86_FEATURE_LFENCE_RDTSC)) { + pr_err("LFENCE selected, but CPU doesn't have a serializing LFENCE. Switching to AUTO select\n"); + spectre_v2_cmd = SPECTRE_V2_CMD_AUTO; + } + + if (spectre_v2_cmd == SPECTRE_V2_CMD_IBRS && !IS_ENABLED(CONFIG_MITIGATION_IBRS_ENTRY)) { + pr_err("IBRS selected but not compiled in. Switching to AUTO select\n"); + spectre_v2_cmd = SPECTRE_V2_CMD_AUTO; + } - if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2) && - (spectre_v2_cmd == SPECTRE_V2_CMD_NONE || spectre_v2_cmd == SPECTRE_V2_CMD_AUTO)) + if (spectre_v2_cmd == SPECTRE_V2_CMD_IBRS && boot_cpu_data.x86_vendor != X86_VENDOR_INTEL) { + pr_err("IBRS selected but not Intel CPU. Switching to AUTO select\n"); + spectre_v2_cmd = SPECTRE_V2_CMD_AUTO; + } + + if (spectre_v2_cmd == SPECTRE_V2_CMD_IBRS && !boot_cpu_has(X86_FEATURE_IBRS)) { + pr_err("IBRS selected but CPU doesn't have IBRS. Switching to AUTO select\n"); + spectre_v2_cmd = SPECTRE_V2_CMD_AUTO; + } + + if (spectre_v2_cmd == SPECTRE_V2_CMD_IBRS && cpu_feature_enabled(X86_FEATURE_XENPV)) { + pr_err("IBRS selected but running as XenPV guest. Switching to AUTO select\n"); + spectre_v2_cmd = SPECTRE_V2_CMD_AUTO; + } + + if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2)) { + spectre_v2_cmd = SPECTRE_V2_CMD_NONE; return; + } switch (spectre_v2_cmd) { case SPECTRE_V2_CMD_NONE: @@ -2538,101 +2523,11 @@ static void update_mds_branch_idle(void) } } -#define MDS_MSG_SMT "MDS CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/mds.html for more details.\n" -#define TAA_MSG_SMT "TAA CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/tsx_async_abort.html for more details.\n" -#define MMIO_MSG_SMT "MMIO Stale Data CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/processor_mmio_stale_data.html for more details.\n" - -void cpu_bugs_smt_update(void) -{ - mutex_lock(&spec_ctrl_mutex); - - if (sched_smt_active() && unprivileged_ebpf_enabled() && - spectre_v2_enabled == SPECTRE_V2_EIBRS_LFENCE) - pr_warn_once(SPECTRE_V2_EIBRS_LFENCE_EBPF_SMT_MSG); - - switch (spectre_v2_user_stibp) { - case SPECTRE_V2_USER_NONE: - break; - case SPECTRE_V2_USER_STRICT: - case SPECTRE_V2_USER_STRICT_PREFERRED: - update_stibp_strict(); - break; - case SPECTRE_V2_USER_PRCTL: - case SPECTRE_V2_USER_SECCOMP: - update_indir_branch_cond(); - break; - } - - switch (mds_mitigation) { - case MDS_MITIGATION_FULL: - case MDS_MITIGATION_AUTO: - case MDS_MITIGATION_VMWERV: - if (sched_smt_active() && !boot_cpu_has(X86_BUG_MSBDS_ONLY)) - pr_warn_once(MDS_MSG_SMT); - update_mds_branch_idle(); - break; - case MDS_MITIGATION_OFF: - break; - } - - switch (taa_mitigation) { - case TAA_MITIGATION_VERW: - case TAA_MITIGATION_AUTO: - case TAA_MITIGATION_UCODE_NEEDED: - if (sched_smt_active()) - pr_warn_once(TAA_MSG_SMT); - break; - case TAA_MITIGATION_TSX_DISABLED: - case TAA_MITIGATION_OFF: - break; - } - - switch (mmio_mitigation) { - case MMIO_MITIGATION_VERW: - case MMIO_MITIGATION_AUTO: - case MMIO_MITIGATION_UCODE_NEEDED: - if (sched_smt_active()) - pr_warn_once(MMIO_MSG_SMT); - break; - case MMIO_MITIGATION_OFF: - break; - } - - switch (tsa_mitigation) { - case TSA_MITIGATION_USER_KERNEL: - case TSA_MITIGATION_VM: - case TSA_MITIGATION_AUTO: - case TSA_MITIGATION_FULL: - /* - * TSA-SQ can potentially lead to info leakage between - * SMT threads. - */ - if (sched_smt_active()) - static_branch_enable(&cpu_buf_idle_clear); - else - static_branch_disable(&cpu_buf_idle_clear); - break; - case TSA_MITIGATION_NONE: - case TSA_MITIGATION_UCODE_NEEDED: - break; - } - - mutex_unlock(&spec_ctrl_mutex); -} - #undef pr_fmt #define pr_fmt(fmt) "Speculative Store Bypass: " fmt -static enum ssb_mitigation ssb_mode __ro_after_init = SPEC_STORE_BYPASS_NONE; - -/* The kernel command line selection */ -enum ssb_mitigation_cmd { - SPEC_STORE_BYPASS_CMD_NONE, - SPEC_STORE_BYPASS_CMD_AUTO, - SPEC_STORE_BYPASS_CMD_ON, - SPEC_STORE_BYPASS_CMD_PRCTL, - SPEC_STORE_BYPASS_CMD_SECCOMP, -}; +static enum ssb_mitigation ssb_mode __ro_after_init = + IS_ENABLED(CONFIG_MITIGATION_SSB) ? SPEC_STORE_BYPASS_AUTO : SPEC_STORE_BYPASS_NONE; static const char * const ssb_strings[] = { [SPEC_STORE_BYPASS_NONE] = "Vulnerable", @@ -2641,94 +2536,61 @@ static const char * const ssb_strings[] = { [SPEC_STORE_BYPASS_SECCOMP] = "Mitigation: Speculative Store Bypass disabled via prctl and seccomp", }; -static const struct { - const char *option; - enum ssb_mitigation_cmd cmd; -} ssb_mitigation_options[] __initconst = { - { "auto", SPEC_STORE_BYPASS_CMD_AUTO }, /* Platform decides */ - { "on", SPEC_STORE_BYPASS_CMD_ON }, /* Disable Speculative Store Bypass */ - { "off", SPEC_STORE_BYPASS_CMD_NONE }, /* Don't touch Speculative Store Bypass */ - { "prctl", SPEC_STORE_BYPASS_CMD_PRCTL }, /* Disable Speculative Store Bypass via prctl */ - { "seccomp", SPEC_STORE_BYPASS_CMD_SECCOMP }, /* Disable Speculative Store Bypass via prctl and seccomp */ -}; +static bool nossb __ro_after_init; -static enum ssb_mitigation_cmd __init ssb_parse_cmdline(void) +static int __init nossb_parse_cmdline(char *str) { - enum ssb_mitigation_cmd cmd; - char arg[20]; - int ret, i; - - cmd = IS_ENABLED(CONFIG_MITIGATION_SSB) ? - SPEC_STORE_BYPASS_CMD_AUTO : SPEC_STORE_BYPASS_CMD_NONE; - if (cmdline_find_option_bool(boot_command_line, "nospec_store_bypass_disable") || - cpu_mitigations_off()) { - return SPEC_STORE_BYPASS_CMD_NONE; - } else { - ret = cmdline_find_option(boot_command_line, "spec_store_bypass_disable", - arg, sizeof(arg)); - if (ret < 0) - return cmd; + nossb = true; + ssb_mode = SPEC_STORE_BYPASS_NONE; + return 0; +} +early_param("nospec_store_bypass_disable", nossb_parse_cmdline); - for (i = 0; i < ARRAY_SIZE(ssb_mitigation_options); i++) { - if (!match_option(arg, ret, ssb_mitigation_options[i].option)) - continue; +static int __init ssb_parse_cmdline(char *str) +{ + if (!str) + return -EINVAL; - cmd = ssb_mitigation_options[i].cmd; - break; - } + if (nossb) + return 0; - if (i >= ARRAY_SIZE(ssb_mitigation_options)) { - pr_err("unknown option (%s). Switching to default mode\n", arg); - return cmd; - } - } + if (!strcmp(str, "auto")) + ssb_mode = SPEC_STORE_BYPASS_AUTO; + else if (!strcmp(str, "on")) + ssb_mode = SPEC_STORE_BYPASS_DISABLE; + else if (!strcmp(str, "off")) + ssb_mode = SPEC_STORE_BYPASS_NONE; + else if (!strcmp(str, "prctl")) + ssb_mode = SPEC_STORE_BYPASS_PRCTL; + else if (!strcmp(str, "seccomp")) + ssb_mode = IS_ENABLED(CONFIG_SECCOMP) ? + SPEC_STORE_BYPASS_SECCOMP : SPEC_STORE_BYPASS_PRCTL; + else + pr_err("Ignoring unknown spec_store_bypass_disable option (%s).\n", + str); - return cmd; + return 0; } +early_param("spec_store_bypass_disable", ssb_parse_cmdline); static void __init ssb_select_mitigation(void) { - enum ssb_mitigation_cmd cmd; - - if (!boot_cpu_has(X86_FEATURE_SSBD)) - goto out; - - cmd = ssb_parse_cmdline(); - if (!boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS) && - (cmd == SPEC_STORE_BYPASS_CMD_NONE || - cmd == SPEC_STORE_BYPASS_CMD_AUTO)) + if (!boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS)) { + ssb_mode = SPEC_STORE_BYPASS_NONE; return; + } - switch (cmd) { - case SPEC_STORE_BYPASS_CMD_SECCOMP: - /* - * Choose prctl+seccomp as the default mode if seccomp is - * enabled. - */ - if (IS_ENABLED(CONFIG_SECCOMP)) - ssb_mode = SPEC_STORE_BYPASS_SECCOMP; - else - ssb_mode = SPEC_STORE_BYPASS_PRCTL; - break; - case SPEC_STORE_BYPASS_CMD_ON: - ssb_mode = SPEC_STORE_BYPASS_DISABLE; - break; - case SPEC_STORE_BYPASS_CMD_AUTO: + if (ssb_mode == SPEC_STORE_BYPASS_AUTO) { if (should_mitigate_vuln(X86_BUG_SPEC_STORE_BYPASS)) ssb_mode = SPEC_STORE_BYPASS_PRCTL; else ssb_mode = SPEC_STORE_BYPASS_NONE; - break; - case SPEC_STORE_BYPASS_CMD_PRCTL: - ssb_mode = SPEC_STORE_BYPASS_PRCTL; - break; - case SPEC_STORE_BYPASS_CMD_NONE: - break; } -out: - if (boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS)) - pr_info("%s\n", ssb_strings[ssb_mode]); + if (!boot_cpu_has(X86_FEATURE_SSBD)) + ssb_mode = SPEC_STORE_BYPASS_NONE; + + pr_info("%s\n", ssb_strings[ssb_mode]); } static void __init ssb_apply_mitigation(void) @@ -2944,6 +2806,7 @@ static int ssb_prctl_get(struct task_struct *task) return PR_SPEC_DISABLE; case SPEC_STORE_BYPASS_SECCOMP: case SPEC_STORE_BYPASS_PRCTL: + case SPEC_STORE_BYPASS_AUTO: if (task_spec_ssb_force_disable(task)) return PR_SPEC_PRCTL | PR_SPEC_FORCE_DISABLE; if (task_spec_ssb_noexec(task)) @@ -3263,14 +3126,15 @@ ibpb_on_vmexit: static void __init srso_update_mitigation(void) { + if (!boot_cpu_has_bug(X86_BUG_SRSO)) + return; + /* If retbleed is using IBPB, that works for SRSO as well */ if (retbleed_mitigation == RETBLEED_MITIGATION_IBPB && boot_cpu_has(X86_FEATURE_IBPB_BRTYPE)) srso_mitigation = SRSO_MITIGATION_IBPB; - if (boot_cpu_has_bug(X86_BUG_SRSO) && - !cpu_mitigations_off()) - pr_info("%s\n", srso_strings[srso_mitigation]); + pr_info("%s\n", srso_strings[srso_mitigation]); } static void __init srso_apply_mitigation(void) @@ -3331,8 +3195,187 @@ static void __init srso_apply_mitigation(void) } #undef pr_fmt +#define pr_fmt(fmt) "VMSCAPE: " fmt + +enum vmscape_mitigations { + VMSCAPE_MITIGATION_NONE, + VMSCAPE_MITIGATION_AUTO, + VMSCAPE_MITIGATION_IBPB_EXIT_TO_USER, + VMSCAPE_MITIGATION_IBPB_ON_VMEXIT, +}; + +static const char * const vmscape_strings[] = { + [VMSCAPE_MITIGATION_NONE] = "Vulnerable", + /* [VMSCAPE_MITIGATION_AUTO] */ + [VMSCAPE_MITIGATION_IBPB_EXIT_TO_USER] = "Mitigation: IBPB before exit to userspace", + [VMSCAPE_MITIGATION_IBPB_ON_VMEXIT] = "Mitigation: IBPB on VMEXIT", +}; + +static enum vmscape_mitigations vmscape_mitigation __ro_after_init = + IS_ENABLED(CONFIG_MITIGATION_VMSCAPE) ? VMSCAPE_MITIGATION_AUTO : VMSCAPE_MITIGATION_NONE; + +static int __init vmscape_parse_cmdline(char *str) +{ + if (!str) + return -EINVAL; + + if (!strcmp(str, "off")) { + vmscape_mitigation = VMSCAPE_MITIGATION_NONE; + } else if (!strcmp(str, "ibpb")) { + vmscape_mitigation = VMSCAPE_MITIGATION_IBPB_EXIT_TO_USER; + } else if (!strcmp(str, "force")) { + setup_force_cpu_bug(X86_BUG_VMSCAPE); + vmscape_mitigation = VMSCAPE_MITIGATION_AUTO; + } else { + pr_err("Ignoring unknown vmscape=%s option.\n", str); + } + + return 0; +} +early_param("vmscape", vmscape_parse_cmdline); + +static void __init vmscape_select_mitigation(void) +{ + if (!boot_cpu_has_bug(X86_BUG_VMSCAPE) || + !boot_cpu_has(X86_FEATURE_IBPB)) { + vmscape_mitigation = VMSCAPE_MITIGATION_NONE; + return; + } + + if (vmscape_mitigation == VMSCAPE_MITIGATION_AUTO) { + if (should_mitigate_vuln(X86_BUG_VMSCAPE)) + vmscape_mitigation = VMSCAPE_MITIGATION_IBPB_EXIT_TO_USER; + else + vmscape_mitigation = VMSCAPE_MITIGATION_NONE; + } +} + +static void __init vmscape_update_mitigation(void) +{ + if (!boot_cpu_has_bug(X86_BUG_VMSCAPE)) + return; + + if (retbleed_mitigation == RETBLEED_MITIGATION_IBPB || + srso_mitigation == SRSO_MITIGATION_IBPB_ON_VMEXIT) + vmscape_mitigation = VMSCAPE_MITIGATION_IBPB_ON_VMEXIT; + + pr_info("%s\n", vmscape_strings[vmscape_mitigation]); +} + +static void __init vmscape_apply_mitigation(void) +{ + if (vmscape_mitigation == VMSCAPE_MITIGATION_IBPB_EXIT_TO_USER) + setup_force_cpu_cap(X86_FEATURE_IBPB_EXIT_TO_USER); +} + +#undef pr_fmt #define pr_fmt(fmt) fmt +#define MDS_MSG_SMT "MDS CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/mds.html for more details.\n" +#define TAA_MSG_SMT "TAA CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/tsx_async_abort.html for more details.\n" +#define MMIO_MSG_SMT "MMIO Stale Data CPU bug present and SMT on, data leak possible. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/processor_mmio_stale_data.html for more details.\n" +#define VMSCAPE_MSG_SMT "VMSCAPE: SMT on, STIBP is required for full protection. See https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/vmscape.html for more details.\n" + +void cpu_bugs_smt_update(void) +{ + mutex_lock(&spec_ctrl_mutex); + + if (sched_smt_active() && unprivileged_ebpf_enabled() && + spectre_v2_enabled == SPECTRE_V2_EIBRS_LFENCE) + pr_warn_once(SPECTRE_V2_EIBRS_LFENCE_EBPF_SMT_MSG); + + switch (spectre_v2_user_stibp) { + case SPECTRE_V2_USER_NONE: + break; + case SPECTRE_V2_USER_STRICT: + case SPECTRE_V2_USER_STRICT_PREFERRED: + update_stibp_strict(); + break; + case SPECTRE_V2_USER_PRCTL: + case SPECTRE_V2_USER_SECCOMP: + update_indir_branch_cond(); + break; + } + + switch (mds_mitigation) { + case MDS_MITIGATION_FULL: + case MDS_MITIGATION_AUTO: + case MDS_MITIGATION_VMWERV: + if (sched_smt_active() && !boot_cpu_has(X86_BUG_MSBDS_ONLY)) + pr_warn_once(MDS_MSG_SMT); + update_mds_branch_idle(); + break; + case MDS_MITIGATION_OFF: + break; + } + + switch (taa_mitigation) { + case TAA_MITIGATION_VERW: + case TAA_MITIGATION_AUTO: + case TAA_MITIGATION_UCODE_NEEDED: + if (sched_smt_active()) + pr_warn_once(TAA_MSG_SMT); + break; + case TAA_MITIGATION_TSX_DISABLED: + case TAA_MITIGATION_OFF: + break; + } + + switch (mmio_mitigation) { + case MMIO_MITIGATION_VERW: + case MMIO_MITIGATION_AUTO: + case MMIO_MITIGATION_UCODE_NEEDED: + if (sched_smt_active()) + pr_warn_once(MMIO_MSG_SMT); + break; + case MMIO_MITIGATION_OFF: + break; + } + + switch (tsa_mitigation) { + case TSA_MITIGATION_USER_KERNEL: + case TSA_MITIGATION_VM: + case TSA_MITIGATION_AUTO: + case TSA_MITIGATION_FULL: + /* + * TSA-SQ can potentially lead to info leakage between + * SMT threads. + */ + if (sched_smt_active()) + static_branch_enable(&cpu_buf_idle_clear); + else + static_branch_disable(&cpu_buf_idle_clear); + break; + case TSA_MITIGATION_NONE: + case TSA_MITIGATION_UCODE_NEEDED: + break; + } + + switch (vmscape_mitigation) { + case VMSCAPE_MITIGATION_NONE: + case VMSCAPE_MITIGATION_AUTO: + break; + case VMSCAPE_MITIGATION_IBPB_ON_VMEXIT: + case VMSCAPE_MITIGATION_IBPB_EXIT_TO_USER: + /* + * Hypervisors can be attacked across-threads, warn for SMT when + * STIBP is not already enabled system-wide. + * + * Intel eIBRS (!AUTOIBRS) implies STIBP on. + */ + if (!sched_smt_active() || + spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT || + spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT_PREFERRED || + (spectre_v2_in_eibrs_mode(spectre_v2_enabled) && + !boot_cpu_has(X86_FEATURE_AUTOIBRS))) + break; + pr_warn_once(VMSCAPE_MSG_SMT); + break; + } + + mutex_unlock(&spec_ctrl_mutex); +} + #ifdef CONFIG_SYSFS #define L1TF_DEFAULT_MSG "Mitigation: PTE Inversion" @@ -3518,9 +3561,6 @@ static const char *spectre_bhi_state(void) static ssize_t spectre_v2_show_state(char *buf) { - if (spectre_v2_enabled == SPECTRE_V2_LFENCE) - return sysfs_emit(buf, "Vulnerable: LFENCE\n"); - if (spectre_v2_enabled == SPECTRE_V2_EIBRS && unprivileged_ebpf_enabled()) return sysfs_emit(buf, "Vulnerable: eIBRS with unprivileged eBPF\n"); @@ -3578,6 +3618,11 @@ static ssize_t tsa_show_state(char *buf) return sysfs_emit(buf, "%s\n", tsa_strings[tsa_mitigation]); } +static ssize_t vmscape_show_state(char *buf) +{ + return sysfs_emit(buf, "%s\n", vmscape_strings[vmscape_mitigation]); +} + static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr, char *buf, unsigned int bug) { @@ -3644,6 +3689,9 @@ static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr case X86_BUG_TSA: return tsa_show_state(buf); + case X86_BUG_VMSCAPE: + return vmscape_show_state(buf); + default: break; } @@ -3735,6 +3783,11 @@ ssize_t cpu_show_tsa(struct device *dev, struct device_attribute *attr, char *bu { return cpu_show_common(dev, attr, buf, X86_BUG_TSA); } + +ssize_t cpu_show_vmscape(struct device *dev, struct device_attribute *attr, char *buf) +{ + return cpu_show_common(dev, attr, buf, X86_BUG_VMSCAPE); +} #endif void __warn_thunk(void) |