This is a note to let you know that I've just added the patch titled
module/retpoline: Warn about missing retpoline in module
to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: module-retpoline-warn-about-missing-retpoline-in-module.patch and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From foo@baz Fri Feb 23 17:23:58 CET 2018
From: Jack Wang jinpu.wang@profitbricks.com Date: Fri, 23 Feb 2018 11:41:54 +0100 Subject: module/retpoline: Warn about missing retpoline in module To: gregkh@linuxfoundation.org, stable@vger.kernel.org Cc: Andi Kleen ak@linux.intel.com, Thomas Gleixner tglx@linutronix.de, David Woodhouse dwmw2@infradead.org, torvalds@linux-foundation.org, jeyu@kernel.org, arjan@linux.intel.com, David Woodhouse dwmw@amazon.co.uk, Jack Wang jinpu.wang@profitbricks.com Message-ID: 1519382538-15143-6-git-send-email-jinpu.wangl@profitbricks.com
From: Andi Kleen ak@linux.intel.com
(cherry picked from commit caf7501a1b4ec964190f31f9c3f163de252273b8)
There's a risk that a kernel which has full retpoline mitigations becomes vulnerable when a module gets loaded that hasn't been compiled with the right compiler or the right option.
To enable detection of that mismatch at module load time, add a module info string "retpoline" at build time when the module was compiled with retpoline support. This only covers compiled C source, but assembler source or prebuilt object files are not checked.
If a retpoline enabled kernel detects a non retpoline protected module at load time, print a warning and report it in the sysfs vulnerability file.
[ tglx: Massaged changelog ]
Signed-off-by: Andi Kleen ak@linux.intel.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Cc: David Woodhouse dwmw2@infradead.org Cc: gregkh@linuxfoundation.org Cc: torvalds@linux-foundation.org Cc: jeyu@kernel.org Cc: arjan@linux.intel.com Link: https://lkml.kernel.org/r/20180125235028.31211-1-andi@firstfloor.org Signed-off-by: David Woodhouse dwmw@amazon.co.uk [jwang: port to 4.4] Signed-off-by: Jack Wang jinpu.wang@profitbricks.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kernel/cpu/bugs.c | 18 +++++++++++++++++- include/linux/module.h | 9 +++++++++ kernel/module.c | 11 +++++++++++ scripts/mod/modpost.c | 9 +++++++++ 4 files changed, 46 insertions(+), 1 deletion(-)
--- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -10,6 +10,7 @@ #include <linux/init.h> #include <linux/utsname.h> #include <linux/cpu.h> +#include <linux/module.h>
#include <asm/nospec-branch.h> #include <asm/cmdline.h> @@ -93,6 +94,20 @@ static const char *spectre_v2_strings[]
static enum spectre_v2_mitigation spectre_v2_enabled = SPECTRE_V2_NONE;
+static bool spectre_v2_bad_module; + +#ifdef RETPOLINE +bool retpoline_module_ok(bool has_retpoline) +{ + if (spectre_v2_enabled == SPECTRE_V2_NONE || has_retpoline) + return true; + + pr_err("System may be vunerable to spectre v2\n"); + spectre_v2_bad_module = true; + return false; +} +#endif + static void __init spec2_print_if_insecure(const char *reason) { if (boot_cpu_has_bug(X86_BUG_SPECTRE_V2)) @@ -277,6 +292,7 @@ ssize_t cpu_show_spectre_v2(struct devic if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2)) return sprintf(buf, "Not affected\n");
- return sprintf(buf, "%s\n", spectre_v2_strings[spectre_v2_enabled]); + return sprintf(buf, "%s%s\n", spectre_v2_strings[spectre_v2_enabled], + spectre_v2_bad_module ? " - vulnerable module loaded" : ""); } #endif --- a/include/linux/module.h +++ b/include/linux/module.h @@ -789,6 +789,15 @@ static inline void module_bug_finalize(c static inline void module_bug_cleanup(struct module *mod) {} #endif /* CONFIG_GENERIC_BUG */
+#ifdef RETPOLINE +extern bool retpoline_module_ok(bool has_retpoline); +#else +static inline bool retpoline_module_ok(bool has_retpoline) +{ + return true; +} +#endif + #ifdef CONFIG_MODULE_SIG static inline bool module_sig_ok(struct module *module) { --- a/kernel/module.c +++ b/kernel/module.c @@ -2869,6 +2869,15 @@ static struct module *setup_load_info(st return mod; }
+static void check_modinfo_retpoline(struct module *mod, struct load_info *info) +{ + if (retpoline_module_ok(get_modinfo(info, "retpoline"))) + return; + + pr_warn("%s: loading module not compiled with retpoline compiler.\n", + mod->name); +} + static int check_modinfo(struct module *mod, struct load_info *info, int flags) { const char *modmagic = get_modinfo(info, "vermagic"); @@ -2895,6 +2904,8 @@ static int check_modinfo(struct module * add_taint_module(mod, TAINT_OOT_MODULE, LOCKDEP_STILL_OK); }
+ check_modinfo_retpoline(mod, info); + if (get_modinfo(info, "staging")) { add_taint_module(mod, TAINT_CRAP, LOCKDEP_STILL_OK); pr_warn("%s: module is from the staging directory, the quality " --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -2129,6 +2129,14 @@ static void add_intree_flag(struct buffe buf_printf(b, "\nMODULE_INFO(intree, "Y");\n"); }
+/* Cannot check for assembler */ +static void add_retpoline(struct buffer *b) +{ + buf_printf(b, "\n#ifdef RETPOLINE\n"); + buf_printf(b, "MODULE_INFO(retpoline, "Y");\n"); + buf_printf(b, "#endif\n"); +} + static void add_staging_flag(struct buffer *b, const char *name) { static const char *staging_dir = "drivers/staging"; @@ -2473,6 +2481,7 @@ int main(int argc, char **argv)
add_header(&buf, mod); add_intree_flag(&buf, !external_module); + add_retpoline(&buf); add_staging_flag(&buf, mod->name); err |= add_versions(&buf, mod); add_depends(&buf, mod, modules);
Patches currently in stable-queue which might be from jinpu.wang@profitbricks.com are
queue-4.4/x86-paravirt-remove-noreplace-paravirt-cmdline-option.patch queue-4.4/documentation-document-array_index_nospec.patch queue-4.4/kvm-x86-make-indirect-calls-in-emulator-speculation-safe.patch queue-4.4/x86-nospec-fix-header-guards-names.patch queue-4.4/x86-retpoline-avoid-retpolines-for-built-in-__init-functions.patch queue-4.4/vfs-fdtable-prevent-bounds-check-bypass-via-speculative-execution.patch queue-4.4/kvm-nvmx-invvpid-handling-improvements.patch queue-4.4/x86-cpu-bugs-make-retpoline-module-warning-conditional.patch queue-4.4/x86-spectre-check-config_retpoline-in-command-line-parser.patch queue-4.4/x86-implement-array_index_mask_nospec.patch queue-4.4/array_index_nospec-sanitize-speculative-array-de-references.patch queue-4.4/kvm-vmx-make-indirect-call-speculation-safe.patch queue-4.4/x86-spectre-fix-spelling-mistake-vunerable-vulnerable.patch queue-4.4/kvm-nvmx-fix-kernel-panics-induced-by-illegal-invept-invvpid-types.patch queue-4.4/module-retpoline-warn-about-missing-retpoline-in-module.patch queue-4.4/x86-kvm-update-spectre-v1-mitigation.patch queue-4.4/x86-get_user-use-pointer-masking-to-limit-speculation.patch queue-4.4/x86-syscall-sanitize-syscall-table-de-references-under-speculation.patch queue-4.4/kvm-nvmx-vmx_complete_nested_posted_interrupt-can-t-fail.patch queue-4.4/x86-spectre-simplify-spectre_v2-command-line-parsing.patch queue-4.4/x86-speculation-fix-typo-ibrs_att-which-should-be-ibrs_all.patch queue-4.4/x86-spectre-report-get_user-mitigation-for-spectre_v1.patch queue-4.4/x86-introduce-barrier_nospec.patch queue-4.4/kvm-async_pf-fix-df-due-to-inject-page-not-present-and-page-ready-exceptions-simultaneously.patch queue-4.4/kvm-vmx-clean-up-declaration-of-vpid-ept-invalidation-types.patch queue-4.4/x86-bugs-drop-one-mitigation-from-dmesg.patch queue-4.4/x86-retpoline-remove-the-esp-rsp-thunk.patch queue-4.4/nl80211-sanitize-array-index-in-parse_txq_params.patch queue-4.4/kvm-nvmx-kmap-can-t-fail.patch