releases/upstream/2.6.30-rc1/0010-thinkpad-acpi-restrict-access-to-some-firmware-LEDs.patch

   1 From a4d5effcc73749ee3ebbf578d162905e6fa4e07d Mon Sep 17 00:00:00 2001
   2 From: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
   3 Date: Sat, 4 Apr 2009 04:25:49 +0000
   4 Subject: thinkpad-acpi: restrict access to some firmware LEDs
   5
   6 Some of the ThinkPad LEDs indicate critical conditions that can cause
   7 data loss or cause hardware damage when ignored (e.g. force-ejecting
   8 a powered up bay; ignoring a failing battery, or empty battery; force-
   9 undocking with the dock buses still active, etc).
  10
  11 On almost all ThinkPads, LED access is write-only, and the firmware
  12 usually does fire-and-forget signaling on them, so you effectively
  13 lose whatever message the firmware was trying to convey to the user
  14 when you override the LED state, without any chance to restore it.
  15
  16 Restrict access to all LEDs that can convey important alarms, or that
  17 could mislead the user into incorrectly operating the hardware.  This
  18 will make the Lenovo engineers less unhappy about the whole issue.
  19
  20 Allow users that really want it to still control all LEDs, it is the
  21 unaware user that we have to worry about.
  22
  23 Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
  24 Signed-off-by: Len Brown <len.brown@intel.com>
  25 ---
  26  Documentation/laptops/thinkpad-acpi.txt |   11 +++++
  27  drivers/platform/x86/Kconfig            |   24 ++++++++++
  28  drivers/platform/x86/thinkpad_acpi.c    |   76 +++++++++++++++++++++++--------
  29  3 files changed, 91 insertions(+), 20 deletions(-)
  30
  31 diff --git a/Documentation/laptops/thinkpad-acpi.txt b/Documentation/laptops/thinkpad-acpi.txt
  32 index de6f14c..bce1d95 100644
  33 --- a/Documentation/laptops/thinkpad-acpi.txt
  34 +++ b/Documentation/laptops/thinkpad-acpi.txt
  35 @@ -901,6 +901,17 @@ some older ThinkPad models, it is possible to query the status of the
  36  LED indicators as well.  Newer ThinkPads cannot query the real status
  37  of the LED indicators.
  38
  39 +Because misuse of the LEDs could induce an unaware user to perform
  40 +dangerous actions (like undocking or ejecting a bay device while the
  41 +buses are still active), or mask an important alarm (such as a nearly
  42 +empty battery, or a broken battery), access to most LEDs is
  43 +restricted.
  44 +
  45 +Unrestricted access to all LEDs requires that thinkpad-acpi be
  46 +compiled with the CONFIG_THINKPAD_ACPI_UNSAFE_LEDS option enabled.
  47 +Distributions must never enable this option.  Individual users that
  48 +are aware of the consequences are welcome to enabling it.
  49 +
  50  procfs notes:
  51
  52  The available commands are:
  53 diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
  54 index 3608081..d45c6ab 100644
  55 --- a/drivers/platform/x86/Kconfig
  56 +++ b/drivers/platform/x86/Kconfig
  57 @@ -226,6 +226,30 @@ config THINKPAD_ACPI_DEBUG
  58
  59           If you are not sure, say N here.
  60
  61 +config THINKPAD_ACPI_UNSAFE_LEDS
  62 +       bool "Allow control of important LEDs (unsafe)"
  63 +       depends on THINKPAD_ACPI
  64 +       default n
  65 +       ---help---
  66 +         Overriding LED state on ThinkPads can mask important
  67 +         firmware alerts (like critical battery condition), or misled
  68 +         the user into damaging the hardware (undocking or ejecting
  69 +         the bay while buses are still active), etc.
  70 +
  71 +         LED control on the ThinkPad is write-only (with very few
  72 +         exceptions on very ancient models), which makes it
  73 +         impossible to know beforehand if important information will
  74 +         be lost when one changes LED state.
  75 +
  76 +         Users that know what they are doing can enable this option
  77 +         and the driver will allow control of every LED, including
  78 +         the ones on the dock stations.
  79 +
  80 +         Never enable this option on a distribution kernel.
  81 +
  82 +         Say N here, unless you are building a kernel for your own
  83 +         use, and need to control the important firmware LEDs.
  84 +
  85  config THINKPAD_ACPI_DOCK
  86         bool "Legacy Docking Station Support"
  87         depends on THINKPAD_ACPI
  88 diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
  89 index f003fb7..38c34c7 100644
  90 --- a/drivers/platform/x86/thinkpad_acpi.c
  91 +++ b/drivers/platform/x86/thinkpad_acpi.c
  92 @@ -4657,6 +4657,16 @@ static const char * const tpacpi_led_names[TPACPI_LED_NUMLEDS] = {
  93         "tpacpi::unknown_led",
  94         "tpacpi::standby",
  95  };
  96 +#define TPACPI_SAFE_LEDS       0x0081U
  97 +
  98 +static inline bool tpacpi_is_led_restricted(const unsigned int led)
  99 +{
 100 +#ifdef CONFIG_THINKPAD_ACPI_UNSAFE_LEDS
 101 +       return false;
 102 +#else
 103 +       return (TPACPI_SAFE_LEDS & (1 << led)) == 0;
 104 +#endif
 105 +}
 106
 107  static int led_get_status(const unsigned int led)
 108  {
 109 @@ -4694,16 +4704,20 @@ static int led_set_status(const unsigned int led,
 110         switch (led_supported) {
 111         case TPACPI_LED_570:
 112                 /* 570 */
 113 -               if (led > 7)
 114 +               if (unlikely(led > 7))
 115                         return -EINVAL;
 116 +               if (unlikely(tpacpi_is_led_restricted(led)))
 117 +                       return -EPERM;
 118                 if (!acpi_evalf(led_handle, NULL, NULL, "vdd",
 119                                 (1 << led), led_sled_arg1[ledstatus]))
 120                         rc = -EIO;
 121                 break;
 122         case TPACPI_LED_OLD:
 123                 /* 600e/x, 770e, 770x, A21e, A2xm/p, T20-22, X20 */
 124 -               if (led > 7)
 125 +               if (unlikely(led > 7))
 126                         return -EINVAL;
 127 +               if (unlikely(tpacpi_is_led_restricted(led)))
 128 +                       return -EPERM;
 129                 rc = ec_write(TPACPI_LED_EC_HLMS, (1 << led));
 130                 if (rc >= 0)
 131                         rc = ec_write(TPACPI_LED_EC_HLBL,
 132 @@ -4714,6 +4728,10 @@ static int led_set_status(const unsigned int led,
 133                 break;
 134         case TPACPI_LED_NEW:
 135                 /* all others */
 136 +               if (unlikely(led >= TPACPI_LED_NUMLEDS))
 137 +                       return -EINVAL;
 138 +               if (unlikely(tpacpi_is_led_restricted(led)))
 139 +                       return -EPERM;
 140                 if (!acpi_evalf(led_handle, NULL, NULL, "vdd",
 141                                 led, led_led_arg1[ledstatus]))
 142                         rc = -EIO;
 143 @@ -4806,6 +4824,30 @@ static void led_exit(void)
 144         kfree(tpacpi_leds);
 145  }
 146
 147 +static int __init tpacpi_init_led(unsigned int led)
 148 +{
 149 +       int rc;
 150 +
 151 +       tpacpi_leds[led].led = led;
 152 +
 153 +       tpacpi_leds[led].led_classdev.brightness_set = &led_sysfs_set;
 154 +       tpacpi_leds[led].led_classdev.blink_set = &led_sysfs_blink_set;
 155 +       if (led_supported == TPACPI_LED_570)
 156 +               tpacpi_leds[led].led_classdev.brightness_get =
 157 +                                               &led_sysfs_get;
 158 +
 159 +       tpacpi_leds[led].led_classdev.name = tpacpi_led_names[led];
 160 +
 161 +       INIT_WORK(&tpacpi_leds[led].work, led_set_status_worker);
 162 +
 163 +       rc = led_classdev_register(&tpacpi_pdev->dev,
 164 +                               &tpacpi_leds[led].led_classdev);
 165 +       if (rc < 0)
 166 +               tpacpi_leds[led].led_classdev.name = NULL;
 167 +
 168 +       return rc;
 169 +}
 170 +
 171  static int __init led_init(struct ibm_init_struct *iibm)
 172  {
 173         unsigned int i;
 174 @@ -4839,27 +4881,21 @@ static int __init led_init(struct ibm_init_struct *iibm)
 175         }
 176
 177         for (i = 0; i < TPACPI_LED_NUMLEDS; i++) {
 178 -               tpacpi_leds[i].led = i;
 179 -
 180 -               tpacpi_leds[i].led_classdev.brightness_set = &led_sysfs_set;
 181 -               tpacpi_leds[i].led_classdev.blink_set = &led_sysfs_blink_set;
 182 -               if (led_supported == TPACPI_LED_570)
 183 -                       tpacpi_leds[i].led_classdev.brightness_get =
 184 -                                                       &led_sysfs_get;
 185 -
 186 -               tpacpi_leds[i].led_classdev.name = tpacpi_led_names[i];
 187 -
 188 -               INIT_WORK(&tpacpi_leds[i].work, led_set_status_worker);
 189 -
 190 -               rc = led_classdev_register(&tpacpi_pdev->dev,
 191 -                                          &tpacpi_leds[i].led_classdev);
 192 -               if (rc < 0) {
 193 -                       tpacpi_leds[i].led_classdev.name = NULL;
 194 -                       led_exit();
 195 -                       return rc;
 196 +               if (!tpacpi_is_led_restricted(i)) {
 197 +                       rc = tpacpi_init_led(i);
 198 +                       if (rc < 0) {
 199 +                               led_exit();
 200 +                               return rc;
 201 +                       }
 202                 }
 203         }
 204
 205 +#ifdef CONFIG_THINKPAD_ACPI_UNSAFE_LEDS
 206 +       if (led_supported != TPACPI_LED_NONE)
 207 +               printk(TPACPI_NOTICE
 208 +                       "warning: userspace override of important "
 209 +                       "firmware LEDs is enabled\n");
 210 +#endif
 211         return (led_supported != TPACPI_LED_NONE)? 0 : 1;
 212  }
 213
 214 --
 215 1.6.2.1
 216