From patchwork Fri Oct 20 17:40:23 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: "Limonciello, Mario" X-Patchwork-Id: 10020819 X-Patchwork-Delegate: dvhart@infradead.org Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id BD9D260211 for ; Fri, 20 Oct 2017 17:43:45 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A5D5028F24 for ; Fri, 20 Oct 2017 17:43:45 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9A7CA28F30; Fri, 20 Oct 2017 17:43:45 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.3 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI, RCVD_IN_SORBS_SPAM, T_DKIM_INVALID autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C189028F24 for ; Fri, 20 Oct 2017 17:43:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753740AbdJTRnS (ORCPT ); Fri, 20 Oct 2017 13:43:18 -0400 Received: from esa3.dell-outbound.iphmx.com ([68.232.153.94]:47360 "EHLO esa3.dell-outbound.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753578AbdJTRkh (ORCPT ); Fri, 20 Oct 2017 13:40:37 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=dell.com; i=@dell.com; q=dns/txt; s=smtpout; t=1508520872; x=1540056872; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=RFBLoeEkWOpsyzZs3LZBT+cByLWJwIUqD/gcjxvPXBY=; b=aSN0jcZXUkxaRCscMuvoK932otYITaz8qv6ZqE1DYA87Ao7fE9dccCyv drZ0EiXllsp3BvYoos/ukCtmgVBTWA2NKHUX0dLLcLDb1+O81CNEXLyTD igb6nuBOjgq7BNt2eDCGNej76btbrE0ra1sQZDuK1FUyVoTTJGxnGJ2Vl Y=; Received: from esa5.dell-outbound2.iphmx.com ([68.232.153.203]) by esa3.dell-outbound.iphmx.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 20 Oct 2017 12:34:31 -0500 Received: from ausc60ps301.us.dell.com ([143.166.148.206]) by esa5.dell-outbound2.iphmx.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 20 Oct 2017 23:38:40 +0600 X-LoopCount0: from 10.208.86.39 X-IronPort-AV: E=Sophos;i="5.43,405,1503378000"; d="scan'208";a="1047299844" X-DLP: DLP_GlobalPCIDSS From: Mario Limonciello To: dvhart@infradead.org, Andy Shevchenko Cc: LKML , platform-driver-x86@vger.kernel.org, Andy Lutomirski , quasisec@google.com, pali.rohar@gmail.com, rjw@rjwysocki.net, mjg59@google.com, hch@lst.de, Greg KH , Alan Cox , Mario Limonciello Subject: [PATCH v11 08/15] platform/x86: dell-smbios: Add a sysfs interface for SMBIOS tokens Date: Fri, 20 Oct 2017 12:40:23 -0500 Message-Id: <363404cf80b9060fca645b5e64bda8de75f59b56.1508515469.git.mario.limonciello@dell.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: References: MIME-Version: 1.0 In-Reply-To: References: Sender: platform-driver-x86-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: platform-driver-x86@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Currently userspace tools can access system tokens via the dcdbas kernel module and a SMI call that will cause the platform to execute SMM code. With a goal in mind of deprecating the dcdbas kernel module a different method for accessing these tokens from userspace needs to be created. This is intentionally marked to only be readable as a process with CAP_SYS_ADMIN as it can contain sensitive information about the platform's configuration. While adding this interface I found that some tokens are duplicated. These need to be ignored from sysfs to avoid duplicate files. MAINTAINERS was missing for this driver. Add myself and Pali to maintainers list for it. Signed-off-by: Mario Limonciello Reviewed-by: Edward O'Callaghan --- .../ABI/testing/sysfs-platform-dell-smbios | 21 ++ MAINTAINERS | 7 + drivers/platform/x86/dell-smbios.c | 212 ++++++++++++++++++++- 3 files changed, 239 insertions(+), 1 deletion(-) create mode 100644 Documentation/ABI/testing/sysfs-platform-dell-smbios diff --git a/Documentation/ABI/testing/sysfs-platform-dell-smbios b/Documentation/ABI/testing/sysfs-platform-dell-smbios new file mode 100644 index 000000000000..205d3b6361e0 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-platform-dell-smbios @@ -0,0 +1,21 @@ +What: /sys/devices/platform//tokens/* +Date: November 2017 +KernelVersion: 4.15 +Contact: "Mario Limonciello" +Description: + A read-only description of Dell platform tokens + available on the machine. + + Each token attribute is available as a pair of + sysfs attributes readable by a process with + CAP_SYS_ADMIN. + + For example the token ID "5" would be available + as the following attributes: + + 0005_location + 0005_value + + Tokens will vary from machine to machine, and + only tokens available on that machine will be + displayed. diff --git a/MAINTAINERS b/MAINTAINERS index f4cf35950b08..09e774f1d0b2 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -3978,6 +3978,13 @@ M: "Maciej W. Rozycki" S: Maintained F: drivers/net/fddi/defxx.* +DELL SMBIOS DRIVER +M: Pali Rohár +M: Mario Limonciello +L: platform-driver-x86@vger.kernel.org +S: Maintained +F: drivers/platform/x86/dell-smbios.* + DELL LAPTOP DRIVER M: Matthew Garrett M: Pali Rohár diff --git a/drivers/platform/x86/dell-smbios.c b/drivers/platform/x86/dell-smbios.c index 7e779278d054..9e2b396861bb 100644 --- a/drivers/platform/x86/dell-smbios.c +++ b/drivers/platform/x86/dell-smbios.c @@ -16,10 +16,12 @@ #include #include +#include #include #include #include #include +#include #include #include #include "../../firmware/dcdbas.h" @@ -39,7 +41,11 @@ static DEFINE_MUTEX(buffer_mutex); static int da_command_address; static int da_command_code; static int da_num_tokens; +static struct platform_device *platform_device; static struct calling_interface_token *da_tokens; +static struct device_attribute *token_location_attrs; +static struct device_attribute *token_value_attrs; +static struct attribute **token_attrs; int dell_smbios_error(int value) { @@ -157,6 +163,26 @@ static void __init parse_da_table(const struct dmi_header *dm) da_num_tokens += tokens; } +static void zero_duplicates(struct device *dev) +{ + int i, j; + + for (i = 0; i < da_num_tokens; i++) { + for (j = i+1; j < da_num_tokens; j++) { + if (da_tokens[i].tokenID == 0 || + da_tokens[j].tokenID == 0) + continue; + if (da_tokens[i].tokenID == da_tokens[j].tokenID) { + dev_dbg(dev, "Zeroing dup token ID %x(%x/%x)\n", + da_tokens[j].tokenID, + da_tokens[j].location, + da_tokens[j].value); + da_tokens[j].tokenID = 0; + } + } + } +} + static void __init find_tokens(const struct dmi_header *dm, void *dummy) { switch (dm->type) { @@ -170,6 +196,154 @@ static void __init find_tokens(const struct dmi_header *dm, void *dummy) } } +static int match_attribute(struct device *dev, + struct device_attribute *attr) +{ + int i; + + for (i = 0; i < da_num_tokens * 2; i++) { + if (!token_attrs[i]) + continue; + if (strcmp(token_attrs[i]->name, attr->attr.name) == 0) + return i/2; + } + dev_dbg(dev, "couldn't match: %s\n", attr->attr.name); + return -EINVAL; +} + +static ssize_t location_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + int i; + + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + i = match_attribute(dev, attr); + if (i > 0) + return scnprintf(buf, PAGE_SIZE, "%08x", da_tokens[i].location); + return 0; +} + +static ssize_t value_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + int i; + + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + i = match_attribute(dev, attr); + if (i > 0) + return scnprintf(buf, PAGE_SIZE, "%08x", da_tokens[i].value); + return 0; +} + +static struct attribute_group smbios_attribute_group = { + .name = "tokens" +}; + +static struct platform_driver platform_driver = { + .driver = { + .name = "dell-smbios", + }, +}; + +static int build_tokens_sysfs(struct platform_device *dev) +{ + char buffer_location[13]; + char buffer_value[10]; + char *location_name; + char *value_name; + size_t size; + int ret; + int i, j; + + /* (number of tokens + 1 for null terminated */ + size = sizeof(struct device_attribute) * (da_num_tokens + 1); + token_location_attrs = kzalloc(size, GFP_KERNEL); + if (!token_location_attrs) + return -ENOMEM; + token_value_attrs = kzalloc(size, GFP_KERNEL); + if (!token_value_attrs) + goto out_allocate_value; + + /* need to store both location and value + terminator*/ + size = sizeof(struct attribute *) * ((2 * da_num_tokens) + 1); + token_attrs = kzalloc(size, GFP_KERNEL); + if (!token_attrs) + goto out_allocate_attrs; + + for (i = 0, j = 0; i < da_num_tokens; i++) { + /* skip empty */ + if (da_tokens[i].tokenID == 0) + continue; + /* add location */ + sprintf(buffer_location, "%04x_location", + da_tokens[i].tokenID); + location_name = kstrdup(buffer_location, GFP_KERNEL); + if (location_name == NULL) + goto out_unwind_strings; + sysfs_attr_init(&token_location_attrs[i].attr); + token_location_attrs[i].attr.name = location_name; + token_location_attrs[i].attr.mode = 0444; + token_location_attrs[i].show = location_show; + token_attrs[j++] = &token_location_attrs[i].attr; + + /* add value */ + sprintf(buffer_value, "%04x_value", + da_tokens[i].tokenID); + value_name = kstrdup(buffer_value, GFP_KERNEL); + if (value_name == NULL) + goto loop_fail_create_value; + sysfs_attr_init(&token_value_attrs[i].attr); + token_value_attrs[i].attr.name = value_name; + token_value_attrs[i].attr.mode = 0444; + token_value_attrs[i].show = value_show; + token_attrs[j++] = &token_value_attrs[i].attr; + continue; + +loop_fail_create_value: + kfree(value_name); + goto out_unwind_strings; + } + smbios_attribute_group.attrs = token_attrs; + + ret = sysfs_create_group(&dev->dev.kobj, &smbios_attribute_group); + if (ret) + goto out_unwind_strings; + return 0; + +out_unwind_strings: + for (i = i-1; i > 0; i--) { + kfree(token_location_attrs[i].attr.name); + kfree(token_value_attrs[i].attr.name); + } + kfree(token_attrs); +out_allocate_attrs: + kfree(token_value_attrs); +out_allocate_value: + kfree(token_location_attrs); + + return -ENOMEM; +} + +static void free_group(struct platform_device *pdev) +{ + int i; + + sysfs_remove_group(&pdev->dev.kobj, + &smbios_attribute_group); + for (i = 0; i < da_num_tokens; i++) { + kfree(token_location_attrs[i].attr.name); + kfree(token_value_attrs[i].attr.name); + } + kfree(token_attrs); + kfree(token_value_attrs); + kfree(token_location_attrs); +} + + static int __init dell_smbios_init(void) { const struct dmi_device *valid; @@ -197,9 +371,40 @@ static int __init dell_smbios_init(void) ret = -ENOMEM; goto fail_buffer; } + ret = platform_driver_register(&platform_driver); + if (ret) + goto fail_platform_driver; + + platform_device = platform_device_alloc("dell-smbios", 0); + if (!platform_device) { + ret = -ENOMEM; + goto fail_platform_device_alloc; + } + ret = platform_device_add(platform_device); + if (ret) + goto fail_platform_device_add; + + /* duplicate tokens will cause problems building sysfs files */ + zero_duplicates(&platform_device->dev); + + ret = build_tokens_sysfs(platform_device); + if (ret) + goto fail_create_group; return 0; +fail_create_group: + platform_device_del(platform_device); + +fail_platform_device_add: + platform_device_put(platform_device); + +fail_platform_device_alloc: + platform_driver_unregister(&platform_driver); + +fail_platform_driver: + free_page((unsigned long)buffer); + fail_buffer: kfree(da_tokens); return ret; @@ -207,8 +412,13 @@ static int __init dell_smbios_init(void) static void __exit dell_smbios_exit(void) { - kfree(da_tokens); + if (platform_device) { + free_group(platform_device); + platform_device_unregister(platform_device); + platform_driver_unregister(&platform_driver); + } free_page((unsigned long)buffer); + kfree(da_tokens); } subsys_initcall(dell_smbios_init);