From: Greg Kroah-Hartman Date: Tue, 8 Mar 2022 18:40:09 +0000 (+0100) Subject: 5.15-stable patches X-Git-Tag: v4.9.306~72 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=5ccb556070d3a12cb5e9cec32d14310098492162;p=thirdparty%2Fkernel%2Fstable-queue.git 5.15-stable patches added patches: documentation-hw-vuln-update-spectre-doc.patch x86-bugs-unconditionally-allow-spectre_v2-retpoline-amd.patch x86-speculation-add-eibrs-retpoline-options.patch x86-speculation-include-unprivileged-ebpf-status-in-spectre-v2-mitigation-reporting.patch x86-speculation-rename-retpoline_amd-to-retpoline_lfence.patch x86-speculation-update-link-to-amd-speculation-whitepaper.patch x86-speculation-use-generic-retpoline-by-default-on-amd.patch x86-speculation-warn-about-eibrs-lfence-unprivileged-ebpf-smt.patch x86-speculation-warn-about-spectre-v2-lfence-mitigation.patch --- diff --git a/queue-5.15/documentation-hw-vuln-update-spectre-doc.patch b/queue-5.15/documentation-hw-vuln-update-spectre-doc.patch new file mode 100644 index 00000000000..61afa40141a --- /dev/null +++ b/queue-5.15/documentation-hw-vuln-update-spectre-doc.patch @@ -0,0 +1,106 @@ +From foo@baz Tue Mar 8 07:37:56 PM CET 2022 +From: Peter Zijlstra +Date: Wed, 16 Feb 2022 20:57:02 +0100 +Subject: Documentation/hw-vuln: Update spectre doc + +From: Peter Zijlstra + +commit 5ad3eb1132453b9795ce5fd4572b1c18b292cca9 upstream. + +Update the doc with the new fun. + + [ bp: Massage commit message. ] + +Signed-off-by: Peter Zijlstra (Intel) +Signed-off-by: Borislav Petkov +Reviewed-by: Thomas Gleixner +[fllinden@amazon.com: backported to 5.15] +Signed-off-by: Frank van der Linden +Signed-off-by: Greg Kroah-Hartman +--- + Documentation/admin-guide/hw-vuln/spectre.rst | 42 ++++++++++++++++-------- + Documentation/admin-guide/kernel-parameters.txt | 8 +++- + 2 files changed, 35 insertions(+), 15 deletions(-) + +--- a/Documentation/admin-guide/hw-vuln/spectre.rst ++++ b/Documentation/admin-guide/hw-vuln/spectre.rst +@@ -131,6 +131,19 @@ steer its indirect branch speculations t + speculative execution's side effects left in level 1 cache to infer the + victim's data. + ++Yet another variant 2 attack vector is for the attacker to poison the ++Branch History Buffer (BHB) to speculatively steer an indirect branch ++to a specific Branch Target Buffer (BTB) entry, even if the entry isn't ++associated with the source address of the indirect branch. Specifically, ++the BHB might be shared across privilege levels even in the presence of ++Enhanced IBRS. ++ ++Currently the only known real-world BHB attack vector is via ++unprivileged eBPF. Therefore, it's highly recommended to not enable ++unprivileged eBPF, especially when eIBRS is used (without retpolines). ++For a full mitigation against BHB attacks, it's recommended to use ++retpolines (or eIBRS combined with retpolines). ++ + Attack scenarios + ---------------- + +@@ -364,13 +377,15 @@ The possible values in this file are: + + - Kernel status: + +- ==================================== ================================= +- 'Not affected' The processor is not vulnerable +- 'Vulnerable' Vulnerable, no mitigation +- 'Mitigation: Full generic retpoline' Software-focused mitigation +- 'Mitigation: Full AMD retpoline' AMD-specific software mitigation +- 'Mitigation: Enhanced IBRS' Hardware-focused mitigation +- ==================================== ================================= ++ ======================================== ================================= ++ 'Not affected' The processor is not vulnerable ++ 'Mitigation: None' Vulnerable, no mitigation ++ 'Mitigation: Retpolines' Use Retpoline thunks ++ 'Mitigation: LFENCE' Use LFENCE instructions ++ 'Mitigation: Enhanced IBRS' Hardware-focused mitigation ++ 'Mitigation: Enhanced IBRS + Retpolines' Hardware-focused + Retpolines ++ 'Mitigation: Enhanced IBRS + LFENCE' Hardware-focused + LFENCE ++ ======================================== ================================= + + - Firmware status: Show if Indirect Branch Restricted Speculation (IBRS) is + used to protect against Spectre variant 2 attacks when calling firmware (x86 only). +@@ -584,12 +599,13 @@ kernel command line. + + Specific mitigations can also be selected manually: + +- retpoline +- replace indirect branches +- retpoline,generic +- google's original retpoline +- retpoline,amd +- AMD-specific minimal thunk ++ retpoline auto pick between generic,lfence ++ retpoline,generic Retpolines ++ retpoline,lfence LFENCE; indirect branch ++ retpoline,amd alias for retpoline,lfence ++ eibrs enhanced IBRS ++ eibrs,retpoline enhanced IBRS + Retpolines ++ eibrs,lfence enhanced IBRS + LFENCE + + Not specifying this option is equivalent to + spectre_v2=auto. +--- a/Documentation/admin-guide/kernel-parameters.txt ++++ b/Documentation/admin-guide/kernel-parameters.txt +@@ -5267,8 +5267,12 @@ + Specific mitigations can also be selected manually: + + retpoline - replace indirect branches +- retpoline,generic - google's original retpoline +- retpoline,amd - AMD-specific minimal thunk ++ retpoline,generic - Retpolines ++ retpoline,lfence - LFENCE; indirect branch ++ retpoline,amd - alias for retpoline,lfence ++ eibrs - enhanced IBRS ++ eibrs,retpoline - enhanced IBRS + Retpolines ++ eibrs,lfence - enhanced IBRS + LFENCE + + Not specifying this option is equivalent to + spectre_v2=auto. diff --git a/queue-5.15/series b/queue-5.15/series new file mode 100644 index 00000000000..332561de783 --- /dev/null +++ b/queue-5.15/series @@ -0,0 +1,9 @@ +x86-bugs-unconditionally-allow-spectre_v2-retpoline-amd.patch +x86-speculation-rename-retpoline_amd-to-retpoline_lfence.patch +x86-speculation-add-eibrs-retpoline-options.patch +documentation-hw-vuln-update-spectre-doc.patch +x86-speculation-include-unprivileged-ebpf-status-in-spectre-v2-mitigation-reporting.patch +x86-speculation-use-generic-retpoline-by-default-on-amd.patch +x86-speculation-update-link-to-amd-speculation-whitepaper.patch +x86-speculation-warn-about-spectre-v2-lfence-mitigation.patch +x86-speculation-warn-about-eibrs-lfence-unprivileged-ebpf-smt.patch diff --git a/queue-5.15/x86-bugs-unconditionally-allow-spectre_v2-retpoline-amd.patch b/queue-5.15/x86-bugs-unconditionally-allow-spectre_v2-retpoline-amd.patch new file mode 100644 index 00000000000..2323533e234 --- /dev/null +++ b/queue-5.15/x86-bugs-unconditionally-allow-spectre_v2-retpoline-amd.patch @@ -0,0 +1,38 @@ +From foo@baz Tue Mar 8 07:37:56 PM CET 2022 +From: Peter Zijlstra +Date: Tue, 26 Oct 2021 14:01:46 +0200 +Subject: x86,bugs: Unconditionally allow spectre_v2=retpoline,amd + +From: Peter Zijlstra + +commit f8a66d608a3e471e1202778c2a36cbdc96bae73b upstream. + +Currently Linux prevents usage of retpoline,amd on !AMD hardware, this +is unfriendly and gets in the way of testing. Remove this restriction. + +Signed-off-by: Peter Zijlstra (Intel) +Reviewed-by: Borislav Petkov +Acked-by: Josh Poimboeuf +Tested-by: Alexei Starovoitov +Link: https://lore.kernel.org/r/20211026120310.487348118@infradead.org +Signed-off-by: Greg Kroah-Hartman +--- + arch/x86/kernel/cpu/bugs.c | 7 ------- + 1 file changed, 7 deletions(-) + +--- a/arch/x86/kernel/cpu/bugs.c ++++ b/arch/x86/kernel/cpu/bugs.c +@@ -882,13 +882,6 @@ static enum spectre_v2_mitigation_cmd __ + return SPECTRE_V2_CMD_AUTO; + } + +- if (cmd == SPECTRE_V2_CMD_RETPOLINE_AMD && +- boot_cpu_data.x86_vendor != X86_VENDOR_HYGON && +- boot_cpu_data.x86_vendor != X86_VENDOR_AMD) { +- pr_err("retpoline,amd selected but CPU is not AMD. Switching to AUTO select\n"); +- return SPECTRE_V2_CMD_AUTO; +- } +- + spec_v2_print_cond(mitigation_options[i].option, + mitigation_options[i].secure); + return cmd; diff --git a/queue-5.15/x86-speculation-add-eibrs-retpoline-options.patch b/queue-5.15/x86-speculation-add-eibrs-retpoline-options.patch new file mode 100644 index 00000000000..768c8c27241 --- /dev/null +++ b/queue-5.15/x86-speculation-add-eibrs-retpoline-options.patch @@ -0,0 +1,272 @@ +From foo@baz Tue Mar 8 07:37:56 PM CET 2022 +From: Peter Zijlstra +Date: Wed, 16 Feb 2022 20:57:01 +0100 +Subject: x86/speculation: Add eIBRS + Retpoline options + +From: Peter Zijlstra + +commit 1e19da8522c81bf46b335f84137165741e0d82b7 upstream. + +Thanks to the chaps at VUsec it is now clear that eIBRS is not +sufficient, therefore allow enabling of retpolines along with eIBRS. + +Add spectre_v2=eibrs, spectre_v2=eibrs,lfence and +spectre_v2=eibrs,retpoline options to explicitly pick your preferred +means of mitigation. + +Since there's new mitigations there's also user visible changes in +/sys/devices/system/cpu/vulnerabilities/spectre_v2 to reflect these +new mitigations. + + [ bp: Massage commit message, trim error messages, + do more precise eIBRS mode checking. ] + +Co-developed-by: Josh Poimboeuf +Signed-off-by: Josh Poimboeuf +Signed-off-by: Peter Zijlstra (Intel) +Signed-off-by: Borislav Petkov +Reviewed-by: Patrick Colp +Reviewed-by: Thomas Gleixner +Signed-off-by: Greg Kroah-Hartman +--- + arch/x86/include/asm/nospec-branch.h | 4 - + arch/x86/kernel/cpu/bugs.c | 133 +++++++++++++++++++++++++---------- + 2 files changed, 99 insertions(+), 38 deletions(-) + +--- a/arch/x86/include/asm/nospec-branch.h ++++ b/arch/x86/include/asm/nospec-branch.h +@@ -177,7 +177,9 @@ enum spectre_v2_mitigation { + SPECTRE_V2_NONE, + SPECTRE_V2_RETPOLINE, + SPECTRE_V2_LFENCE, +- SPECTRE_V2_IBRS_ENHANCED, ++ SPECTRE_V2_EIBRS, ++ SPECTRE_V2_EIBRS_RETPOLINE, ++ SPECTRE_V2_EIBRS_LFENCE, + }; + + /* The indirect branch speculation control variants */ +--- a/arch/x86/kernel/cpu/bugs.c ++++ b/arch/x86/kernel/cpu/bugs.c +@@ -665,6 +665,9 @@ enum spectre_v2_mitigation_cmd { + SPECTRE_V2_CMD_RETPOLINE, + SPECTRE_V2_CMD_RETPOLINE_GENERIC, + SPECTRE_V2_CMD_RETPOLINE_LFENCE, ++ SPECTRE_V2_CMD_EIBRS, ++ SPECTRE_V2_CMD_EIBRS_RETPOLINE, ++ SPECTRE_V2_CMD_EIBRS_LFENCE, + }; + + enum spectre_v2_user_cmd { +@@ -737,6 +740,13 @@ spectre_v2_parse_user_cmdline(enum spect + return SPECTRE_V2_USER_CMD_AUTO; + } + ++static inline bool spectre_v2_in_eibrs_mode(enum spectre_v2_mitigation mode) ++{ ++ return (mode == SPECTRE_V2_EIBRS || ++ mode == SPECTRE_V2_EIBRS_RETPOLINE || ++ mode == SPECTRE_V2_EIBRS_LFENCE); ++} ++ + static void __init + spectre_v2_user_select_mitigation(enum spectre_v2_mitigation_cmd v2_cmd) + { +@@ -804,7 +814,7 @@ spectre_v2_user_select_mitigation(enum s + */ + if (!boot_cpu_has(X86_FEATURE_STIBP) || + !smt_possible || +- spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED) ++ spectre_v2_in_eibrs_mode(spectre_v2_enabled)) + return; + + /* +@@ -826,7 +836,9 @@ static const char * const spectre_v2_str + [SPECTRE_V2_NONE] = "Vulnerable", + [SPECTRE_V2_RETPOLINE] = "Mitigation: Retpolines", + [SPECTRE_V2_LFENCE] = "Mitigation: LFENCE", +- [SPECTRE_V2_IBRS_ENHANCED] = "Mitigation: Enhanced IBRS", ++ [SPECTRE_V2_EIBRS] = "Mitigation: Enhanced IBRS", ++ [SPECTRE_V2_EIBRS_LFENCE] = "Mitigation: Enhanced IBRS + LFENCE", ++ [SPECTRE_V2_EIBRS_RETPOLINE] = "Mitigation: Enhanced IBRS + Retpolines", + }; + + static const struct { +@@ -840,6 +852,9 @@ static const struct { + { "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 }, + }; + +@@ -877,15 +892,29 @@ static enum spectre_v2_mitigation_cmd __ + + if ((cmd == SPECTRE_V2_CMD_RETPOLINE || + cmd == SPECTRE_V2_CMD_RETPOLINE_LFENCE || +- cmd == SPECTRE_V2_CMD_RETPOLINE_GENERIC) && ++ cmd == SPECTRE_V2_CMD_RETPOLINE_GENERIC || ++ cmd == SPECTRE_V2_CMD_EIBRS_LFENCE || ++ cmd == SPECTRE_V2_CMD_EIBRS_RETPOLINE) && + !IS_ENABLED(CONFIG_RETPOLINE)) { +- pr_err("%s selected but not compiled in. Switching to AUTO select\n", mitigation_options[i].option); ++ 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 eIBRS. Switching to AUTO select\n", ++ mitigation_options[i].option); + return SPECTRE_V2_CMD_AUTO; + } + +- if ((cmd == SPECTRE_V2_CMD_RETPOLINE_LFENCE) && ++ 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); ++ 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; + } + +@@ -894,6 +923,25 @@ static enum spectre_v2_mitigation_cmd __ + return cmd; + } + ++static enum spectre_v2_mitigation __init spectre_v2_select_retpoline(void) ++{ ++ if (!IS_ENABLED(CONFIG_RETPOLINE)) { ++ pr_err("Kernel not compiled with retpoline; no mitigation available!"); ++ return SPECTRE_V2_NONE; ++ } ++ ++ if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD || ++ boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) { ++ if (!boot_cpu_has(X86_FEATURE_LFENCE_RDTSC)) { ++ pr_err("LFENCE not serializing, switching to generic retpoline\n"); ++ return SPECTRE_V2_RETPOLINE; ++ } ++ return SPECTRE_V2_LFENCE; ++ } ++ ++ return SPECTRE_V2_RETPOLINE; ++} ++ + static void __init spectre_v2_select_mitigation(void) + { + enum spectre_v2_mitigation_cmd cmd = spectre_v2_parse_cmdline(); +@@ -914,49 +962,60 @@ static void __init spectre_v2_select_mit + case SPECTRE_V2_CMD_FORCE: + case SPECTRE_V2_CMD_AUTO: + if (boot_cpu_has(X86_FEATURE_IBRS_ENHANCED)) { +- mode = SPECTRE_V2_IBRS_ENHANCED; +- /* Force it so VMEXIT will restore correctly */ +- x86_spec_ctrl_base |= SPEC_CTRL_IBRS; +- wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base); +- goto specv2_set_mode; ++ mode = SPECTRE_V2_EIBRS; ++ break; + } +- if (IS_ENABLED(CONFIG_RETPOLINE)) +- goto retpoline_auto; ++ ++ mode = spectre_v2_select_retpoline(); + break; ++ + case SPECTRE_V2_CMD_RETPOLINE_LFENCE: +- if (IS_ENABLED(CONFIG_RETPOLINE)) +- goto retpoline_lfence; ++ mode = SPECTRE_V2_LFENCE; + break; ++ + case SPECTRE_V2_CMD_RETPOLINE_GENERIC: +- if (IS_ENABLED(CONFIG_RETPOLINE)) +- goto retpoline_generic; ++ mode = SPECTRE_V2_RETPOLINE; + break; ++ + case SPECTRE_V2_CMD_RETPOLINE: +- if (IS_ENABLED(CONFIG_RETPOLINE)) +- goto retpoline_auto; ++ mode = spectre_v2_select_retpoline(); ++ break; ++ ++ case SPECTRE_V2_CMD_EIBRS: ++ mode = SPECTRE_V2_EIBRS; ++ break; ++ ++ case SPECTRE_V2_CMD_EIBRS_LFENCE: ++ mode = SPECTRE_V2_EIBRS_LFENCE; ++ break; ++ ++ case SPECTRE_V2_CMD_EIBRS_RETPOLINE: ++ mode = SPECTRE_V2_EIBRS_RETPOLINE; + break; + } +- pr_err("Spectre mitigation: kernel not compiled with retpoline; no mitigation available!"); +- return; + +-retpoline_auto: +- if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD || +- boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) { +- retpoline_lfence: +- if (!boot_cpu_has(X86_FEATURE_LFENCE_RDTSC)) { +- pr_err("Spectre mitigation: LFENCE not serializing, switching to generic retpoline\n"); +- goto retpoline_generic; +- } +- mode = SPECTRE_V2_LFENCE; ++ if (spectre_v2_in_eibrs_mode(mode)) { ++ /* Force it so VMEXIT will restore correctly */ ++ x86_spec_ctrl_base |= SPEC_CTRL_IBRS; ++ wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base); ++ } ++ ++ switch (mode) { ++ case SPECTRE_V2_NONE: ++ case SPECTRE_V2_EIBRS: ++ break; ++ ++ case SPECTRE_V2_LFENCE: ++ case SPECTRE_V2_EIBRS_LFENCE: + setup_force_cpu_cap(X86_FEATURE_RETPOLINE_LFENCE); ++ fallthrough; ++ ++ case SPECTRE_V2_RETPOLINE: ++ case SPECTRE_V2_EIBRS_RETPOLINE: + setup_force_cpu_cap(X86_FEATURE_RETPOLINE); +- } else { +- retpoline_generic: +- mode = SPECTRE_V2_RETPOLINE; +- setup_force_cpu_cap(X86_FEATURE_RETPOLINE); ++ break; + } + +-specv2_set_mode: + spectre_v2_enabled = mode; + pr_info("%s\n", spectre_v2_strings[mode]); + +@@ -982,7 +1041,7 @@ specv2_set_mode: + * the CPU supports Enhanced IBRS, kernel might un-intentionally not + * enable IBRS around firmware calls. + */ +- if (boot_cpu_has(X86_FEATURE_IBRS) && mode != SPECTRE_V2_IBRS_ENHANCED) { ++ if (boot_cpu_has(X86_FEATURE_IBRS) && !spectre_v2_in_eibrs_mode(mode)) { + setup_force_cpu_cap(X86_FEATURE_USE_IBRS_FW); + pr_info("Enabling Restricted Speculation for firmware calls\n"); + } +@@ -1691,7 +1750,7 @@ static ssize_t tsx_async_abort_show_stat + + static char *stibp_state(void) + { +- if (spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED) ++ if (spectre_v2_in_eibrs_mode(spectre_v2_enabled)) + return ""; + + switch (spectre_v2_user_stibp) { diff --git a/queue-5.15/x86-speculation-include-unprivileged-ebpf-status-in-spectre-v2-mitigation-reporting.patch b/queue-5.15/x86-speculation-include-unprivileged-ebpf-status-in-spectre-v2-mitigation-reporting.patch new file mode 100644 index 00000000000..121fc1c263d --- /dev/null +++ b/queue-5.15/x86-speculation-include-unprivileged-ebpf-status-in-spectre-v2-mitigation-reporting.patch @@ -0,0 +1,150 @@ +From foo@baz Tue Mar 8 07:37:56 PM CET 2022 +From: Josh Poimboeuf +Date: Fri, 18 Feb 2022 11:49:08 -0800 +Subject: x86/speculation: Include unprivileged eBPF status in Spectre v2 mitigation reporting + +From: Josh Poimboeuf + +commit 44a3918c8245ab10c6c9719dd12e7a8d291980d8 upstream. + +With unprivileged eBPF enabled, eIBRS (without retpoline) is vulnerable +to Spectre v2 BHB-based attacks. + +When both are enabled, print a warning message and report it in the +'spectre_v2' sysfs vulnerabilities file. + +Signed-off-by: Josh Poimboeuf +Signed-off-by: Borislav Petkov +Reviewed-by: Thomas Gleixner +[fllinden@amazon.com: backported to 5.15] +Signed-off-by: Frank van der Linden +Signed-off-by: Greg Kroah-Hartman +--- + arch/x86/kernel/cpu/bugs.c | 35 +++++++++++++++++++++++++++++------ + include/linux/bpf.h | 12 ++++++++++++ + kernel/sysctl.c | 7 +++++++ + 3 files changed, 48 insertions(+), 6 deletions(-) + +--- a/arch/x86/kernel/cpu/bugs.c ++++ b/arch/x86/kernel/cpu/bugs.c +@@ -16,6 +16,7 @@ + #include + #include + #include ++#include + + #include + #include +@@ -650,6 +651,16 @@ static inline const char *spectre_v2_mod + static inline const char *spectre_v2_module_string(void) { return ""; } + #endif + ++#define SPECTRE_V2_EIBRS_EBPF_MSG "WARNING: Unprivileged eBPF is enabled with eIBRS on, data leaks possible via Spectre v2 BHB attacks!\n" ++ ++#ifdef CONFIG_BPF_SYSCALL ++void unpriv_ebpf_notify(int new_state) ++{ ++ if (spectre_v2_enabled == SPECTRE_V2_EIBRS && !new_state) ++ pr_err(SPECTRE_V2_EIBRS_EBPF_MSG); ++} ++#endif ++ + static inline bool match_option(const char *arg, int arglen, const char *opt) + { + int len = strlen(opt); +@@ -994,6 +1005,9 @@ static void __init spectre_v2_select_mit + break; + } + ++ if (mode == SPECTRE_V2_EIBRS && unprivileged_ebpf_enabled()) ++ pr_err(SPECTRE_V2_EIBRS_EBPF_MSG); ++ + if (spectre_v2_in_eibrs_mode(mode)) { + /* Force it so VMEXIT will restore correctly */ + x86_spec_ctrl_base |= SPEC_CTRL_IBRS; +@@ -1780,6 +1794,20 @@ static char *ibpb_state(void) + return ""; + } + ++static ssize_t spectre_v2_show_state(char *buf) ++{ ++ if (spectre_v2_enabled == SPECTRE_V2_EIBRS && unprivileged_ebpf_enabled()) ++ return sprintf(buf, "Vulnerable: Unprivileged eBPF enabled\n"); ++ ++ return sprintf(buf, "%s%s%s%s%s%s\n", ++ spectre_v2_strings[spectre_v2_enabled], ++ ibpb_state(), ++ boot_cpu_has(X86_FEATURE_USE_IBRS_FW) ? ", IBRS_FW" : "", ++ stibp_state(), ++ boot_cpu_has(X86_FEATURE_RSB_CTXSW) ? ", RSB filling" : "", ++ spectre_v2_module_string()); ++} ++ + static ssize_t srbds_show_state(char *buf) + { + return sprintf(buf, "%s\n", srbds_strings[srbds_mitigation]); +@@ -1805,12 +1833,7 @@ static ssize_t cpu_show_common(struct de + return sprintf(buf, "%s\n", spectre_v1_strings[spectre_v1_mitigation]); + + case X86_BUG_SPECTRE_V2: +- return sprintf(buf, "%s%s%s%s%s%s\n", spectre_v2_strings[spectre_v2_enabled], +- ibpb_state(), +- boot_cpu_has(X86_FEATURE_USE_IBRS_FW) ? ", IBRS_FW" : "", +- stibp_state(), +- boot_cpu_has(X86_FEATURE_RSB_CTXSW) ? ", RSB filling" : "", +- spectre_v2_module_string()); ++ return spectre_v2_show_state(buf); + + case X86_BUG_SPEC_STORE_BYPASS: + return sprintf(buf, "%s\n", ssb_strings[ssb_mode]); +--- a/include/linux/bpf.h ++++ b/include/linux/bpf.h +@@ -1666,6 +1666,12 @@ bool bpf_prog_has_kfunc_call(const struc + const struct btf_func_model * + bpf_jit_find_kfunc_model(const struct bpf_prog *prog, + const struct bpf_insn *insn); ++ ++static inline bool unprivileged_ebpf_enabled(void) ++{ ++ return !sysctl_unprivileged_bpf_disabled; ++} ++ + #else /* !CONFIG_BPF_SYSCALL */ + static inline struct bpf_prog *bpf_prog_get(u32 ufd) + { +@@ -1884,6 +1890,12 @@ bpf_jit_find_kfunc_model(const struct bp + { + return NULL; + } ++ ++static inline bool unprivileged_ebpf_enabled(void) ++{ ++ return false; ++} ++ + #endif /* CONFIG_BPF_SYSCALL */ + + void __bpf_free_used_btfs(struct bpf_prog_aux *aux, +--- a/kernel/sysctl.c ++++ b/kernel/sysctl.c +@@ -228,6 +228,10 @@ static int bpf_stats_handler(struct ctl_ + return ret; + } + ++void __weak unpriv_ebpf_notify(int new_state) ++{ ++} ++ + static int bpf_unpriv_handler(struct ctl_table *table, int write, + void *buffer, size_t *lenp, loff_t *ppos) + { +@@ -245,6 +249,9 @@ static int bpf_unpriv_handler(struct ctl + return -EPERM; + *(int *)table->data = unpriv_enable; + } ++ ++ unpriv_ebpf_notify(unpriv_enable); ++ + return ret; + } + #endif /* CONFIG_BPF_SYSCALL && CONFIG_SYSCTL */ diff --git a/queue-5.15/x86-speculation-rename-retpoline_amd-to-retpoline_lfence.patch b/queue-5.15/x86-speculation-rename-retpoline_amd-to-retpoline_lfence.patch new file mode 100644 index 00000000000..a9c1d77f35a --- /dev/null +++ b/queue-5.15/x86-speculation-rename-retpoline_amd-to-retpoline_lfence.patch @@ -0,0 +1,205 @@ +From foo@baz Tue Mar 8 07:37:56 PM CET 2022 +From: "Peter Zijlstra (Intel)" +Date: Wed, 16 Feb 2022 20:57:00 +0100 +Subject: x86/speculation: Rename RETPOLINE_AMD to RETPOLINE_LFENCE + +From: "Peter Zijlstra (Intel)" + +commit d45476d9832409371537013ebdd8dc1a7781f97a upstream. + +The RETPOLINE_AMD name is unfortunate since it isn't necessarily +AMD only, in fact Hygon also uses it. Furthermore it will likely be +sufficient for some Intel processors. Therefore rename the thing to +RETPOLINE_LFENCE to better describe what it is. + +Add the spectre_v2=retpoline,lfence option as an alias to +spectre_v2=retpoline,amd to preserve existing setups. However, the output +of /sys/devices/system/cpu/vulnerabilities/spectre_v2 will be changed. + + [ bp: Fix typos, massage. ] + +Co-developed-by: Josh Poimboeuf +Signed-off-by: Josh Poimboeuf +Signed-off-by: Peter Zijlstra (Intel) +Signed-off-by: Borislav Petkov +Reviewed-by: Thomas Gleixner +[fllinden@amazon.com: backported to 5.15] +Signed-off-by: Frank van der Linden +Signed-off-by: Greg Kroah-Hartman +--- + arch/x86/include/asm/cpufeatures.h | 2 +- + arch/x86/include/asm/nospec-branch.h | 12 ++++++------ + arch/x86/kernel/cpu/bugs.c | 29 ++++++++++++++++++----------- + arch/x86/lib/retpoline.S | 2 +- + tools/arch/x86/include/asm/cpufeatures.h | 2 +- + 5 files changed, 27 insertions(+), 20 deletions(-) + +--- a/arch/x86/include/asm/cpufeatures.h ++++ b/arch/x86/include/asm/cpufeatures.h +@@ -204,7 +204,7 @@ + /* FREE! ( 7*32+10) */ + #define X86_FEATURE_PTI ( 7*32+11) /* Kernel Page Table Isolation enabled */ + #define X86_FEATURE_RETPOLINE ( 7*32+12) /* "" Generic Retpoline mitigation for Spectre variant 2 */ +-#define X86_FEATURE_RETPOLINE_AMD ( 7*32+13) /* "" AMD Retpoline mitigation for Spectre variant 2 */ ++#define X86_FEATURE_RETPOLINE_LFENCE ( 7*32+13) /* "" Use LFENCE for Spectre variant 2 */ + #define X86_FEATURE_INTEL_PPIN ( 7*32+14) /* Intel Processor Inventory Number */ + #define X86_FEATURE_CDP_L2 ( 7*32+15) /* Code and Data Prioritization L2 */ + #define X86_FEATURE_MSR_SPEC_CTRL ( 7*32+16) /* "" MSR SPEC_CTRL is implemented */ +--- a/arch/x86/include/asm/nospec-branch.h ++++ b/arch/x86/include/asm/nospec-branch.h +@@ -81,7 +81,7 @@ + #ifdef CONFIG_RETPOLINE + ALTERNATIVE_2 __stringify(ANNOTATE_RETPOLINE_SAFE; jmp *%\reg), \ + __stringify(jmp __x86_indirect_thunk_\reg), X86_FEATURE_RETPOLINE, \ +- __stringify(lfence; ANNOTATE_RETPOLINE_SAFE; jmp *%\reg), X86_FEATURE_RETPOLINE_AMD ++ __stringify(lfence; ANNOTATE_RETPOLINE_SAFE; jmp *%\reg), X86_FEATURE_RETPOLINE_LFENCE + #else + jmp *%\reg + #endif +@@ -91,7 +91,7 @@ + #ifdef CONFIG_RETPOLINE + ALTERNATIVE_2 __stringify(ANNOTATE_RETPOLINE_SAFE; call *%\reg), \ + __stringify(call __x86_indirect_thunk_\reg), X86_FEATURE_RETPOLINE, \ +- __stringify(lfence; ANNOTATE_RETPOLINE_SAFE; call *%\reg), X86_FEATURE_RETPOLINE_AMD ++ __stringify(lfence; ANNOTATE_RETPOLINE_SAFE; call *%\reg), X86_FEATURE_RETPOLINE_LFENCE + #else + call *%\reg + #endif +@@ -133,7 +133,7 @@ + "lfence;\n" \ + ANNOTATE_RETPOLINE_SAFE \ + "call *%[thunk_target]\n", \ +- X86_FEATURE_RETPOLINE_AMD) ++ X86_FEATURE_RETPOLINE_LFENCE) + + # define THUNK_TARGET(addr) [thunk_target] "r" (addr) + +@@ -163,7 +163,7 @@ + "lfence;\n" \ + ANNOTATE_RETPOLINE_SAFE \ + "call *%[thunk_target]\n", \ +- X86_FEATURE_RETPOLINE_AMD) ++ X86_FEATURE_RETPOLINE_LFENCE) + + # define THUNK_TARGET(addr) [thunk_target] "rm" (addr) + #endif +@@ -175,8 +175,8 @@ + /* The Spectre V2 mitigation variants */ + enum spectre_v2_mitigation { + SPECTRE_V2_NONE, +- SPECTRE_V2_RETPOLINE_GENERIC, +- SPECTRE_V2_RETPOLINE_AMD, ++ SPECTRE_V2_RETPOLINE, ++ SPECTRE_V2_LFENCE, + SPECTRE_V2_IBRS_ENHANCED, + }; + +--- a/arch/x86/kernel/cpu/bugs.c ++++ b/arch/x86/kernel/cpu/bugs.c +@@ -664,7 +664,7 @@ enum spectre_v2_mitigation_cmd { + SPECTRE_V2_CMD_FORCE, + SPECTRE_V2_CMD_RETPOLINE, + SPECTRE_V2_CMD_RETPOLINE_GENERIC, +- SPECTRE_V2_CMD_RETPOLINE_AMD, ++ SPECTRE_V2_CMD_RETPOLINE_LFENCE, + }; + + enum spectre_v2_user_cmd { +@@ -824,8 +824,8 @@ set_mode: + + static const char * const spectre_v2_strings[] = { + [SPECTRE_V2_NONE] = "Vulnerable", +- [SPECTRE_V2_RETPOLINE_GENERIC] = "Mitigation: Full generic retpoline", +- [SPECTRE_V2_RETPOLINE_AMD] = "Mitigation: Full AMD retpoline", ++ [SPECTRE_V2_RETPOLINE] = "Mitigation: Retpolines", ++ [SPECTRE_V2_LFENCE] = "Mitigation: LFENCE", + [SPECTRE_V2_IBRS_ENHANCED] = "Mitigation: Enhanced IBRS", + }; + +@@ -837,7 +837,8 @@ static const struct { + { "off", SPECTRE_V2_CMD_NONE, false }, + { "on", SPECTRE_V2_CMD_FORCE, true }, + { "retpoline", SPECTRE_V2_CMD_RETPOLINE, false }, +- { "retpoline,amd", SPECTRE_V2_CMD_RETPOLINE_AMD, 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 }, + { "auto", SPECTRE_V2_CMD_AUTO, false }, + }; +@@ -875,13 +876,19 @@ static enum spectre_v2_mitigation_cmd __ + } + + if ((cmd == SPECTRE_V2_CMD_RETPOLINE || +- cmd == SPECTRE_V2_CMD_RETPOLINE_AMD || ++ cmd == SPECTRE_V2_CMD_RETPOLINE_LFENCE || + cmd == SPECTRE_V2_CMD_RETPOLINE_GENERIC) && + !IS_ENABLED(CONFIG_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_RETPOLINE_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; ++ } ++ + spec_v2_print_cond(mitigation_options[i].option, + mitigation_options[i].secure); + return cmd; +@@ -916,9 +923,9 @@ static void __init spectre_v2_select_mit + if (IS_ENABLED(CONFIG_RETPOLINE)) + goto retpoline_auto; + break; +- case SPECTRE_V2_CMD_RETPOLINE_AMD: ++ case SPECTRE_V2_CMD_RETPOLINE_LFENCE: + if (IS_ENABLED(CONFIG_RETPOLINE)) +- goto retpoline_amd; ++ goto retpoline_lfence; + break; + case SPECTRE_V2_CMD_RETPOLINE_GENERIC: + if (IS_ENABLED(CONFIG_RETPOLINE)) +@@ -935,17 +942,17 @@ static void __init spectre_v2_select_mit + retpoline_auto: + if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD || + boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) { +- retpoline_amd: ++ retpoline_lfence: + if (!boot_cpu_has(X86_FEATURE_LFENCE_RDTSC)) { + pr_err("Spectre mitigation: LFENCE not serializing, switching to generic retpoline\n"); + goto retpoline_generic; + } +- mode = SPECTRE_V2_RETPOLINE_AMD; +- setup_force_cpu_cap(X86_FEATURE_RETPOLINE_AMD); ++ mode = SPECTRE_V2_LFENCE; ++ setup_force_cpu_cap(X86_FEATURE_RETPOLINE_LFENCE); + setup_force_cpu_cap(X86_FEATURE_RETPOLINE); + } else { + retpoline_generic: +- mode = SPECTRE_V2_RETPOLINE_GENERIC; ++ mode = SPECTRE_V2_RETPOLINE; + setup_force_cpu_cap(X86_FEATURE_RETPOLINE); + } + +--- a/arch/x86/lib/retpoline.S ++++ b/arch/x86/lib/retpoline.S +@@ -34,7 +34,7 @@ SYM_FUNC_START(__x86_indirect_thunk_\reg + + ALTERNATIVE_2 __stringify(ANNOTATE_RETPOLINE_SAFE; jmp *%\reg), \ + __stringify(RETPOLINE \reg), X86_FEATURE_RETPOLINE, \ +- __stringify(lfence; ANNOTATE_RETPOLINE_SAFE; jmp *%\reg), X86_FEATURE_RETPOLINE_AMD ++ __stringify(lfence; ANNOTATE_RETPOLINE_SAFE; jmp *%\reg), X86_FEATURE_RETPOLINE_LFENCE + + SYM_FUNC_END(__x86_indirect_thunk_\reg) + +--- a/tools/arch/x86/include/asm/cpufeatures.h ++++ b/tools/arch/x86/include/asm/cpufeatures.h +@@ -204,7 +204,7 @@ + /* FREE! ( 7*32+10) */ + #define X86_FEATURE_PTI ( 7*32+11) /* Kernel Page Table Isolation enabled */ + #define X86_FEATURE_RETPOLINE ( 7*32+12) /* "" Generic Retpoline mitigation for Spectre variant 2 */ +-#define X86_FEATURE_RETPOLINE_AMD ( 7*32+13) /* "" AMD Retpoline mitigation for Spectre variant 2 */ ++#define X86_FEATURE_RETPOLINE_LFENCE ( 7*32+13) /* "" Use LFENCEs for Spectre variant 2 */ + #define X86_FEATURE_INTEL_PPIN ( 7*32+14) /* Intel Processor Inventory Number */ + #define X86_FEATURE_CDP_L2 ( 7*32+15) /* Code and Data Prioritization L2 */ + #define X86_FEATURE_MSR_SPEC_CTRL ( 7*32+16) /* "" MSR SPEC_CTRL is implemented */ diff --git a/queue-5.15/x86-speculation-update-link-to-amd-speculation-whitepaper.patch b/queue-5.15/x86-speculation-update-link-to-amd-speculation-whitepaper.patch new file mode 100644 index 00000000000..545840b192a --- /dev/null +++ b/queue-5.15/x86-speculation-update-link-to-amd-speculation-whitepaper.patch @@ -0,0 +1,41 @@ +From foo@baz Tue Mar 8 07:37:56 PM CET 2022 +From: Kim Phillips +Date: Mon, 28 Feb 2022 11:23:16 -0600 +Subject: x86/speculation: Update link to AMD speculation whitepaper + +From: Kim Phillips + +commit e9b6013a7ce31535b04b02ba99babefe8a8599fa upstream. + +Update the link to the "Software Techniques for Managing Speculation +on AMD Processors" whitepaper. + +Signed-off-by: Kim Phillips +Signed-off-by: Borislav Petkov +Signed-off-by: Greg Kroah-Hartman +--- + Documentation/admin-guide/hw-vuln/spectre.rst | 6 +++--- + 1 file changed, 3 insertions(+), 3 deletions(-) + +--- a/Documentation/admin-guide/hw-vuln/spectre.rst ++++ b/Documentation/admin-guide/hw-vuln/spectre.rst +@@ -60,8 +60,8 @@ privileged data touched during the specu + Spectre variant 1 attacks take advantage of speculative execution of + conditional branches, while Spectre variant 2 attacks use speculative + execution of indirect branches to leak privileged memory. +-See :ref:`[1] ` :ref:`[5] ` :ref:`[7] ` +-:ref:`[10] ` :ref:`[11] `. ++See :ref:`[1] ` :ref:`[5] ` :ref:`[6] ` ++:ref:`[7] ` :ref:`[10] ` :ref:`[11] `. + + Spectre variant 1 (Bounds Check Bypass) + --------------------------------------- +@@ -746,7 +746,7 @@ AMD white papers: + + .. _spec_ref6: + +-[6] `Software techniques for managing speculation on AMD processors `_. ++[6] `Software techniques for managing speculation on AMD processors `_. + + ARM white papers: + diff --git a/queue-5.15/x86-speculation-use-generic-retpoline-by-default-on-amd.patch b/queue-5.15/x86-speculation-use-generic-retpoline-by-default-on-amd.patch new file mode 100644 index 00000000000..38b2ac2708d --- /dev/null +++ b/queue-5.15/x86-speculation-use-generic-retpoline-by-default-on-amd.patch @@ -0,0 +1,42 @@ +From foo@baz Tue Mar 8 07:37:56 PM CET 2022 +From: Kim Phillips +Date: Mon, 28 Feb 2022 11:23:15 -0600 +Subject: x86/speculation: Use generic retpoline by default on AMD + +From: Kim Phillips + +commit 244d00b5dd4755f8df892c86cab35fb2cfd4f14b upstream. + +AMD retpoline may be susceptible to speculation. The speculation +execution window for an incorrect indirect branch prediction using +LFENCE/JMP sequence may potentially be large enough to allow +exploitation using Spectre V2. + +By default, don't use retpoline,lfence on AMD. Instead, use the +generic retpoline. + +Signed-off-by: Kim Phillips +Signed-off-by: Borislav Petkov +Signed-off-by: Greg Kroah-Hartman +--- + arch/x86/kernel/cpu/bugs.c | 9 --------- + 1 file changed, 9 deletions(-) + +--- a/arch/x86/kernel/cpu/bugs.c ++++ b/arch/x86/kernel/cpu/bugs.c +@@ -941,15 +941,6 @@ static enum spectre_v2_mitigation __init + return SPECTRE_V2_NONE; + } + +- if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD || +- boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) { +- if (!boot_cpu_has(X86_FEATURE_LFENCE_RDTSC)) { +- pr_err("LFENCE not serializing, switching to generic retpoline\n"); +- return SPECTRE_V2_RETPOLINE; +- } +- return SPECTRE_V2_LFENCE; +- } +- + return SPECTRE_V2_RETPOLINE; + } + diff --git a/queue-5.15/x86-speculation-warn-about-eibrs-lfence-unprivileged-ebpf-smt.patch b/queue-5.15/x86-speculation-warn-about-eibrs-lfence-unprivileged-ebpf-smt.patch new file mode 100644 index 00000000000..02ebe81c76d --- /dev/null +++ b/queue-5.15/x86-speculation-warn-about-eibrs-lfence-unprivileged-ebpf-smt.patch @@ -0,0 +1,93 @@ +From foo@baz Tue Mar 8 07:37:56 PM CET 2022 +From: Josh Poimboeuf +Date: Fri, 25 Feb 2022 14:32:28 -0800 +Subject: x86/speculation: Warn about eIBRS + LFENCE + Unprivileged eBPF + SMT + +From: Josh Poimboeuf + +commit 0de05d056afdb00eca8c7bbb0c79a3438daf700c upstream. + +The commit + + 44a3918c8245 ("x86/speculation: Include unprivileged eBPF status in Spectre v2 mitigation reporting") + +added a warning for the "eIBRS + unprivileged eBPF" combination, which +has been shown to be vulnerable against Spectre v2 BHB-based attacks. + +However, there's no warning about the "eIBRS + LFENCE retpoline + +unprivileged eBPF" combo. The LFENCE adds more protection by shortening +the speculation window after a mispredicted branch. That makes an attack +significantly more difficult, even with unprivileged eBPF. So at least +for now the logic doesn't warn about that combination. + +But if you then add SMT into the mix, the SMT attack angle weakens the +effectiveness of the LFENCE considerably. + +So extend the "eIBRS + unprivileged eBPF" warning to also include the +"eIBRS + LFENCE + unprivileged eBPF + SMT" case. + + [ bp: Massage commit message. ] + +Suggested-by: Alyssa Milburn +Signed-off-by: Josh Poimboeuf +Signed-off-by: Borislav Petkov +Signed-off-by: Greg Kroah-Hartman +--- + arch/x86/kernel/cpu/bugs.c | 27 +++++++++++++++++++++++++-- + 1 file changed, 25 insertions(+), 2 deletions(-) + +--- a/arch/x86/kernel/cpu/bugs.c ++++ b/arch/x86/kernel/cpu/bugs.c +@@ -653,12 +653,27 @@ static inline const char *spectre_v2_mod + + #define SPECTRE_V2_LFENCE_MSG "WARNING: LFENCE mitigation is not recommended for this CPU, data leaks possible!\n" + #define SPECTRE_V2_EIBRS_EBPF_MSG "WARNING: Unprivileged eBPF is enabled with eIBRS on, data leaks possible via Spectre v2 BHB attacks!\n" ++#define SPECTRE_V2_EIBRS_LFENCE_EBPF_SMT_MSG "WARNING: Unprivileged eBPF is enabled with eIBRS+LFENCE mitigation and SMT, data leaks possible via Spectre v2 BHB attacks!\n" + + #ifdef CONFIG_BPF_SYSCALL + void unpriv_ebpf_notify(int new_state) + { +- if (spectre_v2_enabled == SPECTRE_V2_EIBRS && !new_state) ++ if (new_state) ++ return; ++ ++ /* Unprivileged eBPF is enabled */ ++ ++ switch (spectre_v2_enabled) { ++ case SPECTRE_V2_EIBRS: + pr_err(SPECTRE_V2_EIBRS_EBPF_MSG); ++ break; ++ case SPECTRE_V2_EIBRS_LFENCE: ++ if (sched_smt_active()) ++ pr_err(SPECTRE_V2_EIBRS_LFENCE_EBPF_SMT_MSG); ++ break; ++ default: ++ break; ++ } + } + #endif + +@@ -1118,6 +1133,10 @@ 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; +@@ -1793,7 +1812,11 @@ static ssize_t spectre_v2_show_state(cha + return sprintf(buf, "Vulnerable: LFENCE\n"); + + if (spectre_v2_enabled == SPECTRE_V2_EIBRS && unprivileged_ebpf_enabled()) +- return sprintf(buf, "Vulnerable: Unprivileged eBPF enabled\n"); ++ return sprintf(buf, "Vulnerable: eIBRS with unprivileged eBPF\n"); ++ ++ if (sched_smt_active() && unprivileged_ebpf_enabled() && ++ spectre_v2_enabled == SPECTRE_V2_EIBRS_LFENCE) ++ return sprintf(buf, "Vulnerable: eIBRS+LFENCE with unprivileged eBPF and SMT\n"); + + return sprintf(buf, "%s%s%s%s%s%s\n", + spectre_v2_strings[spectre_v2_enabled], diff --git a/queue-5.15/x86-speculation-warn-about-spectre-v2-lfence-mitigation.patch b/queue-5.15/x86-speculation-warn-about-spectre-v2-lfence-mitigation.patch new file mode 100644 index 00000000000..d12d933733e --- /dev/null +++ b/queue-5.15/x86-speculation-warn-about-spectre-v2-lfence-mitigation.patch @@ -0,0 +1,62 @@ +From foo@baz Tue Mar 8 07:37:56 PM CET 2022 +From: Josh Poimboeuf +Date: Fri, 25 Feb 2022 14:31:49 -0800 +Subject: x86/speculation: Warn about Spectre v2 LFENCE mitigation + +From: Josh Poimboeuf + +commit eafd987d4a82c7bb5aa12f0e3b4f8f3dea93e678 upstream. + +With: + + f8a66d608a3e ("x86,bugs: Unconditionally allow spectre_v2=retpoline,amd") + +it became possible to enable the LFENCE "retpoline" on Intel. However, +Intel doesn't recommend it, as it has some weaknesses compared to +retpoline. + +Now AMD doesn't recommend it either. + +It can still be left available as a cmdline option. It's faster than +retpoline but is weaker in certain scenarios -- particularly SMT, but +even non-SMT may be vulnerable in some cases. + +So just unconditionally warn if the user requests it on the cmdline. + + [ bp: Massage commit message. ] + +Signed-off-by: Josh Poimboeuf +Signed-off-by: Borislav Petkov +Signed-off-by: Greg Kroah-Hartman +--- + arch/x86/kernel/cpu/bugs.c | 5 +++++ + 1 file changed, 5 insertions(+) + +--- a/arch/x86/kernel/cpu/bugs.c ++++ b/arch/x86/kernel/cpu/bugs.c +@@ -651,6 +651,7 @@ static inline const char *spectre_v2_mod + static inline const char *spectre_v2_module_string(void) { return ""; } + #endif + ++#define SPECTRE_V2_LFENCE_MSG "WARNING: LFENCE mitigation is not recommended for this CPU, data leaks possible!\n" + #define SPECTRE_V2_EIBRS_EBPF_MSG "WARNING: Unprivileged eBPF is enabled with eIBRS on, data leaks possible via Spectre v2 BHB attacks!\n" + + #ifdef CONFIG_BPF_SYSCALL +@@ -972,6 +973,7 @@ static void __init spectre_v2_select_mit + break; + + case SPECTRE_V2_CMD_RETPOLINE_LFENCE: ++ pr_err(SPECTRE_V2_LFENCE_MSG); + mode = SPECTRE_V2_LFENCE; + break; + +@@ -1787,6 +1789,9 @@ static char *ibpb_state(void) + + static ssize_t spectre_v2_show_state(char *buf) + { ++ if (spectre_v2_enabled == SPECTRE_V2_LFENCE) ++ return sprintf(buf, "Vulnerable: LFENCE\n"); ++ + if (spectre_v2_enabled == SPECTRE_V2_EIBRS && unprivileged_ebpf_enabled()) + return sprintf(buf, "Vulnerable: Unprivileged eBPF enabled\n"); +