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x86/bugs: Add AMD retbleed= boot parameter
commit 7fbf47c7ce
upstream.
Add the "retbleed=<value>" boot parameter to select a mitigation for
RETBleed. Possible values are "off", "auto" and "unret"
(JMP2RET mitigation). The default value is "auto".
Currently, "retbleed=auto" will select the unret mitigation on
AMD and Hygon and no mitigation on Intel (JMP2RET is not effective on
Intel).
[peterz: rebase; add hygon]
[jpoimboe: cleanups]
Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
[cascardo: this effectively remove the UNRET mitigation as an option, so it
has to be complemented by a later pick of the same commit later. This is
done in order to pick retbleed_select_mitigation]
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Suleiman Souhlal <suleiman@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
parent
bd2b18f6d2
commit
c79ea34ffb
2 changed files with 85 additions and 1 deletions
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@ -4132,6 +4132,18 @@
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retain_initrd [RAM] Keep initrd memory after extraction
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retbleed= [X86] Control mitigation of RETBleed (Arbitrary
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Speculative Code Execution with Return Instructions)
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vulnerability.
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off - unconditionally disable
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auto - automatically select a migitation
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Selecting 'auto' will choose a mitigation method at run
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time according to the CPU.
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Not specifying this option is equivalent to retbleed=auto.
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rfkill.default_state=
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0 "airplane mode". All wifi, bluetooth, wimax, gps, fm,
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etc. communication is blocked by default.
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@ -36,6 +36,7 @@
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#include "cpu.h"
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static void __init spectre_v1_select_mitigation(void);
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static void __init retbleed_select_mitigation(void);
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static void __init spectre_v2_select_mitigation(void);
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static void __init ssb_select_mitigation(void);
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static void __init l1tf_select_mitigation(void);
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@ -111,6 +112,12 @@ void __init check_bugs(void)
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/* Select the proper CPU mitigations before patching alternatives: */
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spectre_v1_select_mitigation();
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retbleed_select_mitigation();
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/*
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* spectre_v2_select_mitigation() relies on the state set by
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* retbleed_select_mitigation(); specifically the STIBP selection is
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* forced for UNRET.
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*/
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spectre_v2_select_mitigation();
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ssb_select_mitigation();
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l1tf_select_mitigation();
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@ -705,6 +712,71 @@ static int __init nospectre_v1_cmdline(char *str)
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}
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early_param("nospectre_v1", nospectre_v1_cmdline);
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#undef pr_fmt
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#define pr_fmt(fmt) "RETBleed: " fmt
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enum retbleed_mitigation {
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RETBLEED_MITIGATION_NONE,
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};
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enum retbleed_mitigation_cmd {
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RETBLEED_CMD_OFF,
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RETBLEED_CMD_AUTO,
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};
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const char * const retbleed_strings[] = {
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[RETBLEED_MITIGATION_NONE] = "Vulnerable",
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};
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static enum retbleed_mitigation retbleed_mitigation __ro_after_init =
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RETBLEED_MITIGATION_NONE;
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static enum retbleed_mitigation_cmd retbleed_cmd __ro_after_init =
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RETBLEED_CMD_AUTO;
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static int __init retbleed_parse_cmdline(char *str)
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{
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if (!str)
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return -EINVAL;
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if (!strcmp(str, "off"))
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retbleed_cmd = RETBLEED_CMD_OFF;
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else if (!strcmp(str, "auto"))
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retbleed_cmd = RETBLEED_CMD_AUTO;
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else
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pr_err("Unknown retbleed option (%s). Defaulting to 'auto'\n", str);
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return 0;
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}
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early_param("retbleed", retbleed_parse_cmdline);
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#define RETBLEED_UNTRAIN_MSG "WARNING: BTB untrained return thunk mitigation is only effective on AMD/Hygon!\n"
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#define RETBLEED_COMPILER_MSG "WARNING: kernel not compiled with RETPOLINE or -mfunction-return capable compiler!\n"
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static void __init retbleed_select_mitigation(void)
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{
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if (!boot_cpu_has_bug(X86_BUG_RETBLEED) || cpu_mitigations_off())
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return;
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switch (retbleed_cmd) {
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case RETBLEED_CMD_OFF:
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return;
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case RETBLEED_CMD_AUTO:
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default:
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if (!boot_cpu_has_bug(X86_BUG_RETBLEED))
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break;
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break;
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}
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switch (retbleed_mitigation) {
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default:
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break;
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}
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pr_info("%s\n", retbleed_strings[retbleed_mitigation]);
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}
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#undef pr_fmt
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#define pr_fmt(fmt) "Spectre V2 : " fmt
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@ -1901,7 +1973,7 @@ static ssize_t srbds_show_state(char *buf)
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static ssize_t retbleed_show_state(char *buf)
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{
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return sprintf(buf, "Vulnerable\n");
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return sprintf(buf, "%s\n", retbleed_strings[retbleed_mitigation]);
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}
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static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr,
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