diff options
author | Borislav Petkov <bp@suse.de> | 2018-01-02 14:19:48 +0100 |
---|---|---|
committer | Ben Hutchings <ben@decadent.org.uk> | 2018-01-07 01:46:52 +0000 |
commit | 95fdffcc2c581654627e79553b45180da58793a7 (patch) | |
tree | 795cfd6ec227bc48f5f6fffab5d7018db422b8e8 | |
parent | e424b40fd8e8905af4362b053cb9c976c2e69385 (diff) | |
download | linux-stable-95fdffcc2c581654627e79553b45180da58793a7.tar.gz linux-stable-95fdffcc2c581654627e79553b45180da58793a7.tar.bz2 linux-stable-95fdffcc2c581654627e79553b45180da58793a7.zip |
x86/kaiser: Check boottime cmdline params
AMD (and possibly other vendors) are not affected by the leak
KAISER is protecting against.
Keep the "nopti" for traditional reasons and add pti=<on|off|auto>
like upstream.
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
-rw-r--r-- | Documentation/kernel-parameters.txt | 6 | ||||
-rw-r--r-- | arch/x86/mm/kaiser.c | 59 |
2 files changed, 47 insertions, 18 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 56b678603531..ccaf4be39d17 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -2245,6 +2245,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted. pt. [PARIDE] See Documentation/blockdev/paride.txt. + pti= [X86_64] + Control KAISER user/kernel address space isolation: + on - enable + off - disable + auto - default setting + pty.legacy_count= [KNL] Number of legacy pty's. Overwrites compiled-in default number. diff --git a/arch/x86/mm/kaiser.c b/arch/x86/mm/kaiser.c index 5d0be21c32a6..f479fd824090 100644 --- a/arch/x86/mm/kaiser.c +++ b/arch/x86/mm/kaiser.c @@ -20,6 +20,7 @@ extern struct mm_struct init_mm; #include <asm/pgtable.h> #include <asm/pgalloc.h> #include <asm/desc.h> +#include <asm/cmdline.h> int kaiser_enabled __read_mostly = 1; EXPORT_SYMBOL(kaiser_enabled); /* for inlined TLB flush functions */ @@ -264,6 +265,43 @@ static void __init kaiser_init_all_pgds(void) WARN_ON(__ret); \ } while (0) +void __init kaiser_check_boottime_disable(void) +{ + bool enable = true; + char arg[5]; + int ret; + + ret = cmdline_find_option(boot_command_line, "pti", arg, sizeof(arg)); + if (ret > 0) { + if (!strncmp(arg, "on", 2)) + goto enable; + + if (!strncmp(arg, "off", 3)) + goto disable; + + if (!strncmp(arg, "auto", 4)) + goto skip; + } + + if (cmdline_find_option_bool(boot_command_line, "nopti")) + goto disable; + +skip: + if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) + goto disable; + +enable: + if (enable) + setup_force_cpu_cap(X86_FEATURE_KAISER); + + return; + +disable: + pr_info("Kernel/User page tables isolation: disabled\n"); + kaiser_enabled = 0; + setup_clear_cpu_cap(X86_FEATURE_KAISER); +} + /* * If anything in here fails, we will likely die on one of the * first kernel->user transitions and init will die. But, we @@ -275,12 +313,10 @@ void __init kaiser_init(void) { int cpu; - if (!kaiser_enabled) { - setup_clear_cpu_cap(X86_FEATURE_KAISER); - return; - } + kaiser_check_boottime_disable(); - setup_force_cpu_cap(X86_FEATURE_KAISER); + if (!kaiser_enabled) + return; kaiser_init_all_pgds(); @@ -413,16 +449,3 @@ void kaiser_flush_tlb_on_return_to_user(void) X86_CR3_PCID_USER_FLUSH | KAISER_SHADOW_PGD_OFFSET); } EXPORT_SYMBOL(kaiser_flush_tlb_on_return_to_user); - -static int __init x86_nokaiser_setup(char *s) -{ - /* nopti doesn't accept parameters */ - if (s) - return -EINVAL; - - kaiser_enabled = 0; - pr_info("Kernel/User page tables isolation: disabled\n"); - - return 0; -} -early_param("nopti", x86_nokaiser_setup); |