patches/kernel/0191-x86-pti-Add-the-pti-cmdline-option-and-documentation.patch

   1 From d6b6a8fa92efd244f759ab8ded4ccaebac2b762c Mon Sep 17 00:00:00 2001
   2 From: Borislav Petkov <bp@suse.de>
   3 Date: Tue, 12 Dec 2017 14:39:52 +0100
   4 Subject: [PATCH 191/233] x86/pti: Add the pti= cmdline option and
   5  documentation
   6 MIME-Version: 1.0
   7 Content-Type: text/plain; charset=UTF-8
   8 Content-Transfer-Encoding: 8bit
   9
  10 CVE-2017-5754
  11
  12 Keep the "nopti" optional for traditional reasons.
  13
  14 [ tglx: Don't allow force on when running on XEN PV and made 'on'
  15         printout conditional ]
  16
  17 Requested-by: Linus Torvalds <torvalds@linux-foundation.org>
  18 Signed-off-by: Borislav Petkov <bp@suse.de>
  19 Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
  20 Cc: Andy Lutomirski <luto@kernel.org>
  21 Cc: Andy Lutomirsky <luto@kernel.org>
  22 Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
  23 Cc: Borislav Petkov <bp@alien8.de>
  24 Cc: Brian Gerst <brgerst@gmail.com>
  25 Cc: Dave Hansen <dave.hansen@intel.com>
  26 Cc: Dave Hansen <dave.hansen@linux.intel.com>
  27 Cc: David Laight <David.Laight@aculab.com>
  28 Cc: Denys Vlasenko <dvlasenk@redhat.com>
  29 Cc: Eduardo Valentin <eduval@amazon.com>
  30 Cc: Greg KH <gregkh@linuxfoundation.org>
  31 Cc: H. Peter Anvin <hpa@zytor.com>
  32 Cc: Josh Poimboeuf <jpoimboe@redhat.com>
  33 Cc: Juergen Gross <jgross@suse.com>
  34 Cc: Linus Torvalds <torvalds@linux-foundation.org>
  35 Cc: Peter Zijlstra <peterz@infradead.org>
  36 Cc: Will Deacon <will.deacon@arm.com>
  37 Cc: aliguori@amazon.com
  38 Cc: daniel.gruss@iaik.tugraz.at
  39 Cc: hughd@google.com
  40 Cc: keescook@google.com
  41 Link: https://lkml.kernel.org/r/20171212133952.10177-1-bp@alien8.de
  42 Signed-off-by: Ingo Molnar <mingo@kernel.org>
  43 (cherry picked from commit 41f4c20b57a4890ea7f56ff8717cc83fefb8d537)
  44 Signed-off-by: Andy Whitcroft <apw@canonical.com>
  45 Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
  46 (cherry picked from commit 96d3670fa8f88989fb7c0be5172a1378143f3296)
  47 Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
  48 ---
  49  Documentation/admin-guide/kernel-parameters.txt |  6 ++++++
  50  arch/x86/mm/pti.c                               | 26 ++++++++++++++++++++++++-
  51  2 files changed, 31 insertions(+), 1 deletion(-)
  52
  53 diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
  54 index e2a4608da5d2..b4d2edf316db 100644
  55 --- a/Documentation/admin-guide/kernel-parameters.txt
  56 +++ b/Documentation/admin-guide/kernel-parameters.txt
  57 @@ -3247,6 +3247,12 @@
  58         pt.             [PARIDE]
  59                         See Documentation/blockdev/paride.txt.
  60
  61 +       pti=            [X86_64]
  62 +                       Control user/kernel address space isolation:
  63 +                       on - enable
  64 +                       off - disable
  65 +                       auto - default setting
  66 +
  67         pty.legacy_count=
  68                         [KNL] Number of legacy pty's. Overwrites compiled-in
  69                         default number.
  70 diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c
  71 index 375f23a758bc..a13f6b109865 100644
  72 --- a/arch/x86/mm/pti.c
  73 +++ b/arch/x86/mm/pti.c
  74 @@ -54,21 +54,45 @@ static void __init pti_print_if_insecure(const char *reason)
  75                 pr_info("%s\n", reason);
  76  }
  77
  78 +static void __init pti_print_if_secure(const char *reason)
  79 +{
  80 +       if (!boot_cpu_has_bug(X86_BUG_CPU_INSECURE))
  81 +               pr_info("%s\n", reason);
  82 +}
  83 +
  84  void __init pti_check_boottime_disable(void)
  85  {
  86 +       char arg[5];
  87 +       int ret;
  88 +
  89         if (hypervisor_is_type(X86_HYPER_XEN_PV)) {
  90                 pti_print_if_insecure("disabled on XEN PV.");
  91                 return;
  92         }
  93
  94 +       ret = cmdline_find_option(boot_command_line, "pti", arg, sizeof(arg));
  95 +       if (ret > 0)  {
  96 +               if (ret == 3 && !strncmp(arg, "off", 3)) {
  97 +                       pti_print_if_insecure("disabled on command line.");
  98 +                       return;
  99 +               }
 100 +               if (ret == 2 && !strncmp(arg, "on", 2)) {
 101 +                       pti_print_if_secure("force enabled on command line.");
 102 +                       goto enable;
 103 +               }
 104 +               if (ret == 4 && !strncmp(arg, "auto", 4))
 105 +                       goto autosel;
 106 +       }
 107 +
 108         if (cmdline_find_option_bool(boot_command_line, "nopti")) {
 109                 pti_print_if_insecure("disabled on command line.");
 110                 return;
 111         }
 112
 113 +autosel:
 114         if (!boot_cpu_has_bug(X86_BUG_CPU_INSECURE))
 115                 return;
 116 -
 117 +enable:
 118         setup_force_cpu_cap(X86_FEATURE_PTI);
 119  }
 120
 121 --
 122 2.14.2
 123