From patchwork Thu Mar 31 11:36:40 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Renninger X-Patchwork-Id: 679021 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by demeter1.kernel.org (8.14.4/8.14.3) with ESMTP id p2VBXkZ3004640 for ; Thu, 31 Mar 2011 11:33:47 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751908Ab1CaLdq (ORCPT ); Thu, 31 Mar 2011 07:33:46 -0400 Received: from cantor.suse.de ([195.135.220.2]:41147 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752056Ab1CaLdo (ORCPT ); Thu, 31 Mar 2011 07:33:44 -0400 Received: from relay1.suse.de (charybdis-ext.suse.de [195.135.221.2]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.suse.de (Postfix) with ESMTP id 92F6C5362F; Thu, 31 Mar 2011 13:33:43 +0200 (CEST) From: Thomas Renninger To: lenb@kernel.org Cc: Thomas Renninger , "Rafael J. Wysocki" , rui.zhang@intel.com, linux-acpi@vger.kernel.org Subject: [PATCH 3/3] acpi: Split out custom_method functionality into an own driver Date: Thu, 31 Mar 2011 13:36:40 +0200 Message-Id: <1301571400-9861-3-git-send-email-trenn@suse.de> X-Mailer: git-send-email 1.7.3.4 In-Reply-To: <1301571400-9861-1-git-send-email-trenn@suse.de> References: <1301571400-9861-1-git-send-email-trenn@suse.de> Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.6 (demeter1.kernel.org [140.211.167.41]); Thu, 31 Mar 2011 11:33:47 +0000 (UTC) diff --git a/Documentation/acpi/method-customizing.txt b/Documentation/acpi/method-customizing.txt index 3e1d25a..5f55373 100644 --- a/Documentation/acpi/method-customizing.txt +++ b/Documentation/acpi/method-customizing.txt @@ -66,3 +66,8 @@ Note: We can use a kernel with multiple custom ACPI method running, But each individual write to debugfs can implement a SINGLE method override. i.e. if we want to insert/override multiple ACPI methods, we need to redo step c) ~ g) for multiple times. + +Note: Be aware that root can mis-use this driver to modify arbitrary + memory and gain additional rights, if root's privileges got + restricted (for example if root is not allowed to load additional + modules after boot). diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig index 2aa042a..3feeec8 100644 --- a/drivers/acpi/Kconfig +++ b/drivers/acpi/Kconfig @@ -381,6 +381,21 @@ config ACPI_HED which is used to report some hardware errors notified via SCI, mainly the corrected errors. +config ACPI_CUSTOM_METHOD + tristate "Allow ACPI methods to be inserted/replaced at run time" + depends on DEBUG_FS + default n + help + This debug facility allows ACPI AML methods to me inserted and/or + replaced without rebooting the system. For details refer to: + Documentation/acpi/method-customizing.txt. + + NOTE: This option is security sensitive, because it allows arbitrary + kernel memory to be written to by root (uid=0) users, allowing them + to bypass certain security measures (e.g. if root is not allowed to + load additional kernel modules after boot, this feature may be used + to override that restriction). + source "drivers/acpi/apei/Kconfig" endif # ACPI diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile index d113fa5..cba0b23 100644 --- a/drivers/acpi/Makefile +++ b/drivers/acpi/Makefile @@ -62,6 +62,7 @@ obj-$(CONFIG_ACPI_SBS) += sbs.o obj-$(CONFIG_ACPI_POWER_METER) += power_meter.o obj-$(CONFIG_ACPI_HED) += hed.o obj-$(CONFIG_ACPI_EC_DEBUGFS) += ec_sys.o +obj-$(CONFIG_ACPI_CUSTOM_METHOD)+= custom_method.o # processor has its own "processor." module_param namespace processor-y := processor_driver.o processor_throttling.o diff --git a/drivers/acpi/debugfs.c b/drivers/acpi/debugfs.c index e7abc6e..182a9fc 100644 --- a/drivers/acpi/debugfs.c +++ b/drivers/acpi/debugfs.c @@ -3,9 +3,6 @@ */ #include -#include -#include -#include #include #include @@ -13,84 +10,9 @@ ACPI_MODULE_NAME("debugfs"); struct dentry *acpi_debugfs_dir; -static struct dentry *cm_dentry; - -/* /sys/kernel/debug/acpi/custom_method */ - -static ssize_t cm_write(struct file *file, const char __user * user_buf, - size_t count, loff_t *ppos) -{ - static char *buf; - static u32 max_size; - static u32 uncopied_bytes; - - struct acpi_table_header table; - acpi_status status; - - if (!(*ppos)) { - /* parse the table header to get the table length */ - if (count <= sizeof(struct acpi_table_header)) - return -EINVAL; - if (copy_from_user(&table, user_buf, - sizeof(struct acpi_table_header))) - return -EFAULT; - uncopied_bytes = max_size = table.length; - buf = kzalloc(max_size, GFP_KERNEL); - if (!buf) - return -ENOMEM; - } - - if (buf == NULL) - return -EINVAL; - - if ((*ppos > max_size) || - (*ppos + count > max_size) || - (*ppos + count < count) || - (count > uncopied_bytes)) - return -EINVAL; - - if (copy_from_user(buf + (*ppos), user_buf, count)) { - kfree(buf); - buf = NULL; - return -EFAULT; - } - - uncopied_bytes -= count; - *ppos += count; - - if (!uncopied_bytes) { - status = acpi_install_method(buf); - kfree(buf); - buf = NULL; - if (ACPI_FAILURE(status)) - return -EINVAL; - add_taint(TAINT_OVERRIDDEN_ACPI_TABLE); - } - - return count; -} - -static const struct file_operations cm_fops = { - .write = cm_write, - .llseek = default_llseek, -}; - -static int __init acpi_custom_method_init(void) -{ - if (!acpi_debugfs_dir) - return -ENOENT; - - cm_dentry = debugfs_create_file("custom_method", S_IWUSR, - acpi_debugfs_dir, NULL, &cm_fops); - if (!cm_dentry) - return -ENODEV; - - return 0; -} +EXPORT_SYMBOL_GPL(acpi_debugfs_dir); void __init acpi_debugfs_init(void) { acpi_debugfs_dir = debugfs_create_dir("acpi", NULL); - - acpi_custom_method_init(); }