diff options
| -rw-r--r-- | Documentation/laptops/thinkpad-acpi.txt | 4 | ||||
| -rw-r--r-- | drivers/platform/x86/Kconfig | 10 | ||||
| -rw-r--r-- | drivers/platform/x86/thinkpad_acpi.c | 15 |
3 files changed, 25 insertions, 4 deletions
diff --git a/Documentation/laptops/thinkpad-acpi.txt b/Documentation/laptops/thinkpad-acpi.txt index f5056c7fb5be..387eb9c6bf5d 100644 --- a/Documentation/laptops/thinkpad-acpi.txt +++ b/Documentation/laptops/thinkpad-acpi.txt @@ -650,6 +650,10 @@ LCD, CRT or DVI (if available). The following commands are available: echo expand_toggle > /proc/acpi/ibm/video echo video_switch > /proc/acpi/ibm/video +NOTE: Access to this feature is restricted to processes owning the +CAP_SYS_ADMIN capability for safety reasons, as it can interact badly +enough with some versions of X.org to crash it. + Each video output device can be enabled or disabled individually. Reading /proc/acpi/ibm/video shows the status of each device. diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig index 55ca39dea42e..6e2a4ca4162e 100644 --- a/drivers/platform/x86/Kconfig +++ b/drivers/platform/x86/Kconfig @@ -291,9 +291,15 @@ config THINKPAD_ACPI_VIDEO server running, phase of the moon, and the current mood of Schroedinger's cat. If you can use X.org's RandR to control your ThinkPad's video output ports instead of this feature, - don't think twice: do it and say N here to save some memory. + don't think twice: do it and say N here to save memory and avoid + bad interactions with X.org. - If you are not sure, say Y here. + NOTE: access to this feature is limited to processes with the + CAP_SYS_ADMIN capability, to avoid local DoS issues in platforms + where it interacts badly with X.org. + + If you are not sure, say Y here but do try to check if you could + be using X.org RandR instead. config THINKPAD_ACPI_HOTKEY_POLL bool "Support NVRAM polling for hot keys" diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c index ac5544c96aec..7e51d5be8cc0 100644 --- a/drivers/platform/x86/thinkpad_acpi.c +++ b/drivers/platform/x86/thinkpad_acpi.c @@ -281,6 +281,7 @@ struct ibm_init_struct { char param[32]; int (*init) (struct ibm_init_struct *); + mode_t base_procfs_mode; struct ibm_struct *data; }; @@ -4620,6 +4621,10 @@ static int video_read(struct seq_file *m) return 0; } + /* Even reads can crash X.org, so... */ + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + status = video_outputsw_get(); if (status < 0) return status; @@ -4653,6 +4658,10 @@ static int video_write(char *buf) if (video_supported == TPACPI_VIDEO_NONE) return -ENODEV; + /* Even reads can crash X.org, let alone writes... */ + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + enable = 0; disable = 0; @@ -7887,9 +7896,10 @@ static int __init ibm_init(struct ibm_init_struct *iibm) "%s installed\n", ibm->name); if (ibm->read) { - mode_t mode; + mode_t mode = iibm->base_procfs_mode; - mode = S_IRUGO; + if (!mode) + mode = S_IRUGO; if (ibm->write) mode |= S_IWUSR; entry = proc_create_data(ibm->name, mode, proc_dir, @@ -8080,6 +8090,7 @@ static struct ibm_init_struct ibms_init[] __initdata = { #ifdef CONFIG_THINKPAD_ACPI_VIDEO { .init = video_init, + .base_procfs_mode = S_IRUSR, .data = &video_driver_data, }, #endif |