| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <20240912190857.235849-18-david.kaplan@amd.com>
Date: Thu, 12 Sep 2024 14:08:40 -0500
From: David Kaplan <david.kaplan@....com>
To: Thomas Gleixner <tglx@...utronix.de>, Borislav Petkov <bp@...en8.de>,
Peter Zijlstra <peterz@...radead.org>, Josh Poimboeuf <jpoimboe@...nel.org>,
Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>, Ingo Molnar
<mingo@...hat.com>, Dave Hansen <dave.hansen@...ux.intel.com>,
<x86@...nel.org>, "H . Peter Anvin" <hpa@...or.com>
CC: <linux-kernel@...r.kernel.org>
Subject: [RFC PATCH 17/34] x86/bugs: Restructure srso mitigation
Restructure srso to use select/update/apply functions to create
consistent vulnerability handling. Like with retbleed, the command line
options directly select mitigations which can later be modified.
Signed-off-by: David Kaplan <david.kaplan@....com>
---
arch/x86/kernel/cpu/bugs.c | 136 ++++++++++++++++++-------------------
1 file changed, 68 insertions(+), 68 deletions(-)
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index ba10aa37d949..334fd2c5251d 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -84,6 +84,8 @@ static void __init srbds_select_mitigation(void);
static void __init srbds_apply_mitigation(void);
static void __init l1d_flush_select_mitigation(void);
static void __init srso_select_mitigation(void);
+static void __init srso_update_mitigation(void);
+static void __init srso_apply_mitigation(void);
static void __init gds_select_mitigation(void);
static void __init gds_apply_mitigation(void);
static void __init bhi_select_mitigation(void);
@@ -200,11 +202,6 @@ void __init cpu_select_mitigations(void)
rfds_select_mitigation();
srbds_select_mitigation();
l1d_flush_select_mitigation();
-
- /*
- * srso_select_mitigation() depends and must run after
- * retbleed_select_mitigation().
- */
srso_select_mitigation();
gds_select_mitigation();
bhi_select_mitigation();
@@ -220,6 +217,7 @@ void __init cpu_select_mitigations(void)
taa_update_mitigation();
mmio_update_mitigation();
rfds_update_mitigation();
+ srso_update_mitigation();
spectre_v1_apply_mitigation();
spectre_v2_apply_mitigation();
@@ -232,6 +230,7 @@ void __init cpu_select_mitigations(void)
mmio_apply_mitigation();
rfds_apply_mitigation();
srbds_apply_mitigation();
+ srso_apply_mitigation();
gds_apply_mitigation();
bhi_apply_mitigation();
}
@@ -2637,6 +2636,7 @@ early_param("l1tf", l1tf_cmdline);
enum srso_mitigation {
SRSO_MITIGATION_NONE,
+ SRSO_MITIGATION_AUTO,
SRSO_MITIGATION_UCODE_NEEDED,
SRSO_MITIGATION_SAFE_RET_UCODE_NEEDED,
SRSO_MITIGATION_MICROCODE,
@@ -2645,14 +2645,6 @@ enum srso_mitigation {
SRSO_MITIGATION_IBPB_ON_VMEXIT,
};
-enum srso_mitigation_cmd {
- SRSO_CMD_OFF,
- SRSO_CMD_MICROCODE,
- SRSO_CMD_SAFE_RET,
- SRSO_CMD_IBPB,
- SRSO_CMD_IBPB_ON_VMEXIT,
-};
-
static const char * const srso_strings[] = {
[SRSO_MITIGATION_NONE] = "Vulnerable",
[SRSO_MITIGATION_UCODE_NEEDED] = "Vulnerable: No microcode",
@@ -2663,8 +2655,7 @@ static const char * const srso_strings[] = {
[SRSO_MITIGATION_IBPB_ON_VMEXIT] = "Mitigation: IBPB on VMEXIT only"
};
-static enum srso_mitigation srso_mitigation __ro_after_init = SRSO_MITIGATION_NONE;
-static enum srso_mitigation_cmd srso_cmd __ro_after_init = SRSO_CMD_SAFE_RET;
+static enum srso_mitigation srso_mitigation __ro_after_init = SRSO_MITIGATION_AUTO;
static int __init srso_parse_cmdline(char *str)
{
@@ -2672,15 +2663,15 @@ static int __init srso_parse_cmdline(char *str)
return -EINVAL;
if (!strcmp(str, "off"))
- srso_cmd = SRSO_CMD_OFF;
+ srso_mitigation = SRSO_MITIGATION_NONE;
else if (!strcmp(str, "microcode"))
- srso_cmd = SRSO_CMD_MICROCODE;
+ srso_mitigation = SRSO_MITIGATION_MICROCODE;
else if (!strcmp(str, "safe-ret"))
- srso_cmd = SRSO_CMD_SAFE_RET;
+ srso_mitigation = SRSO_MITIGATION_SAFE_RET;
else if (!strcmp(str, "ibpb"))
- srso_cmd = SRSO_CMD_IBPB;
+ srso_mitigation = SRSO_MITIGATION_IBPB;
else if (!strcmp(str, "ibpb-vmexit"))
- srso_cmd = SRSO_CMD_IBPB_ON_VMEXIT;
+ srso_mitigation = SRSO_MITIGATION_IBPB_ON_VMEXIT;
else
pr_err("Ignoring unknown SRSO option (%s).", str);
@@ -2696,12 +2687,16 @@ static void __init srso_select_mitigation(void)
if (!boot_cpu_has_bug(X86_BUG_SRSO) ||
cpu_mitigations_off() ||
- srso_cmd == SRSO_CMD_OFF) {
+ srso_mitigation == SRSO_MITIGATION_NONE) {
if (boot_cpu_has(X86_FEATURE_SBPB))
x86_pred_cmd = PRED_CMD_SBPB;
return;
}
+ /* Default mitigation */
+ if (srso_mitigation == SRSO_MITIGATION_AUTO)
+ srso_mitigation = SRSO_MITIGATION_SAFE_RET;
+
if (has_microcode) {
/*
* Zen1/2 with SMT off aren't vulnerable after the right
@@ -2713,29 +2708,59 @@ static void __init srso_select_mitigation(void)
setup_force_cpu_cap(X86_FEATURE_SRSO_NO);
return;
}
-
- if (retbleed_mitigation == RETBLEED_MITIGATION_IBPB) {
- srso_mitigation = SRSO_MITIGATION_IBPB;
- goto out;
- }
} else {
pr_warn("IBPB-extending microcode not applied!\n");
pr_warn(SRSO_NOTICE);
- /* may be overwritten by SRSO_CMD_SAFE_RET below */
- srso_mitigation = SRSO_MITIGATION_UCODE_NEEDED;
+ /* Fall-back to Safe-RET */
+ srso_mitigation = SRSO_MITIGATION_SAFE_RET_UCODE_NEEDED;
}
- switch (srso_cmd) {
- case SRSO_CMD_MICROCODE:
- if (has_microcode) {
- srso_mitigation = SRSO_MITIGATION_MICROCODE;
- pr_warn(SRSO_NOTICE);
- }
+ switch (srso_mitigation) {
+ case SRSO_MITIGATION_MICROCODE:
+ pr_warn(SRSO_NOTICE);
+ break;
+
+ case SRSO_MITIGATION_SAFE_RET:
+ case SRSO_MITIGATION_SAFE_RET_UCODE_NEEDED:
+ if (!IS_ENABLED(CONFIG_MITIGATION_SRSO))
+ pr_err("WARNING: kernel not compiled with MITIGATION_SRSO.\n");
break;
- case SRSO_CMD_SAFE_RET:
- if (IS_ENABLED(CONFIG_MITIGATION_SRSO)) {
+ case SRSO_MITIGATION_IBPB:
+ if (!IS_ENABLED(CONFIG_MITIGATION_IBPB_ENTRY))
+ pr_err("WARNING: kernel not compiled with MITIGATION_IBPB_ENTRY.\n");
+ break;
+
+ case SRSO_MITIGATION_IBPB_ON_VMEXIT:
+ if (!IS_ENABLED(CONFIG_MITIGATION_SRSO))
+ pr_err("WARNING: kernel not compiled with MITIGATION_SRSO.\n");
+ break;
+ default:
+ break;
+ }
+}
+
+static void __init srso_update_mitigation(void)
+{
+ /* If retbleed is using IBPB, that works for SRSO as well */
+ if (retbleed_mitigation == RETBLEED_MITIGATION_IBPB)
+ srso_mitigation = SRSO_MITIGATION_IBPB;
+
+ pr_info("%s\n", srso_strings[srso_mitigation]);
+}
+
+static void __init srso_apply_mitigation(void)
+{
+ if (!boot_cpu_has_bug(X86_BUG_SRSO) ||
+ srso_mitigation == SRSO_MITIGATION_NONE) {
+ if (boot_cpu_has(X86_FEATURE_SBPB))
+ x86_pred_cmd = PRED_CMD_SBPB;
+ return;
+ }
+ switch (srso_mitigation) {
+ case SRSO_MITIGATION_SAFE_RET:
+ case SRSO_MITIGATION_SAFE_RET_UCODE_NEEDED:
/*
* Enable the return thunk for generated code
* like ftrace, static_call, etc.
@@ -2750,42 +2775,17 @@ static void __init srso_select_mitigation(void)
setup_force_cpu_cap(X86_FEATURE_SRSO);
x86_return_thunk = srso_return_thunk;
}
- if (has_microcode)
- srso_mitigation = SRSO_MITIGATION_SAFE_RET;
- else
- srso_mitigation = SRSO_MITIGATION_SAFE_RET_UCODE_NEEDED;
- } else {
- pr_err("WARNING: kernel not compiled with MITIGATION_SRSO.\n");
- }
- break;
-
- case SRSO_CMD_IBPB:
- if (IS_ENABLED(CONFIG_MITIGATION_IBPB_ENTRY)) {
- if (has_microcode) {
- setup_force_cpu_cap(X86_FEATURE_ENTRY_IBPB);
- srso_mitigation = SRSO_MITIGATION_IBPB;
- }
- } else {
- pr_err("WARNING: kernel not compiled with MITIGATION_IBPB_ENTRY.\n");
- }
- break;
-
- case SRSO_CMD_IBPB_ON_VMEXIT:
- if (IS_ENABLED(CONFIG_MITIGATION_SRSO)) {
- if (!boot_cpu_has(X86_FEATURE_ENTRY_IBPB) && has_microcode) {
- setup_force_cpu_cap(X86_FEATURE_IBPB_ON_VMEXIT);
- srso_mitigation = SRSO_MITIGATION_IBPB_ON_VMEXIT;
- }
- } else {
- pr_err("WARNING: kernel not compiled with MITIGATION_SRSO.\n");
- }
break;
+ case SRSO_MITIGATION_IBPB:
+ setup_force_cpu_cap(X86_FEATURE_ENTRY_IBPB);
+ break;
+ case SRSO_MITIGATION_IBPB_ON_VMEXIT:
+ setup_force_cpu_cap(X86_FEATURE_IBPB_ON_VMEXIT);
+ break;
default:
- break;
+ break;
}
-out:
- pr_info("%s\n", srso_strings[srso_mitigation]);
}
#undef pr_fmt
--
2.34.1
Powered by blists - more mailing lists