| Message ID | 20220315195630.3209-2-markpearson@lenovo.com (mailing list archive) |
|---|---|
| State | Changes Requested, archived |
| Headers | show |
| Series | [v2,1/2] Documentation: syfs-class-firmware-attributes: Lenovo Certificate support | expand |
Hi Mark, On 3/15/22 20:56, Mark Pearson wrote: > Implementation of certificate authentication feature for Lenovo > platforms. This allows for signed updates of BIOS settings. > > Functionality supported: > - Cert support available check. At initialisation check if BIOS > supports certification authentication and if a certificate is > installed. Enable the sysfs nodes appropriately > - certificate and signature authentication attributes to enable > a user to install, update and delete a certificate using signed > signatures > - certificate_thumbprint to confirm installed certificate details > - support to go from certificate to password based authentication > - signature and save_signature attributes needed for setting BIOS > attributes using certificate authentication. > > Tested on X1 Carbon 10 with special trial BIOS. This feature is not > generally available yet but will be released later this year. > > Note, I also cleaned up the formating of the GUIDs when I was adding > the new defines. Hope that's OK to combine in this commit. > > Signed-off-by: Mark Pearson <markpearson@lenovo.com> > --- > Changes in v2: > - Combined set_signature with signature and moved save_signature under > the authorisation folder > - utility function to strip CR from string > - Clean up code as recommended from review Thanks this is looking better now, I still have a few small remarks, see below. > > drivers/platform/x86/think-lmi.c | 560 +++++++++++++++++++++++++------ > drivers/platform/x86/think-lmi.h | 5 + > 2 files changed, 461 insertions(+), 104 deletions(-) > > diff --git a/drivers/platform/x86/think-lmi.c b/drivers/platform/x86/think-lmi.c > index 0b73e16cccea..1db34a6c94c2 100644 > --- a/drivers/platform/x86/think-lmi.c > +++ b/drivers/platform/x86/think-lmi.c > @@ -16,6 +16,7 @@ > #include <linux/fs.h> > #include <linux/string.h> > #include <linux/types.h> > +#include <linux/dmi.h> > #include <linux/wmi.h> > #include "firmware_attributes_class.h" > #include "think-lmi.h" > @@ -25,95 +26,66 @@ module_param(debug_support, bool, 0444); > MODULE_PARM_DESC(debug_support, "Enable debug command support"); > > /* > - * Name: > - * Lenovo_BiosSetting > - * Description: > - * Get item name and settings for current LMI instance. > - * Type: > - * Query > - * Returns: > - * "Item,Value" > - * Example: > - * "WakeOnLAN,Enable" > + * Name: BiosSetting > + * Description: Get item name and settings for current LMI instance. > + * Type: Query > + * Returns: "Item,Value" > + * Example: "WakeOnLAN,Enable" > */ > #define LENOVO_BIOS_SETTING_GUID "51F5230E-9677-46CD-A1CF-C0B23EE34DB7" > > /* > - * Name: > - * Lenovo_SetBiosSetting > - * Description: > - * Change the BIOS setting to the desired value using the Lenovo_SetBiosSetting > - * class. To save the settings, use the Lenovo_SaveBiosSetting class. > + * Name: SetBiosSetting > + * Description: Change the BIOS setting to the desired value using the SetBiosSetting > + * class. To save the settings, use the SaveBiosSetting class. > * BIOS settings and values are case sensitive. > * After making changes to the BIOS settings, you must reboot the computer > * before the changes will take effect. > - * Type: > - * Method > - * Arguments: > - * "Item,Value,Password,Encoding,KbdLang;" > - * Example: > - * "WakeOnLAN,Disable,pa55w0rd,ascii,us;" > + * Type: Method > + * Arguments: "Item,Value,Password,Encoding,KbdLang;" > + * Example: "WakeOnLAN,Disable,pa55w0rd,ascii,us;" > */ > #define LENOVO_SET_BIOS_SETTINGS_GUID "98479A64-33F5-4E33-A707-8E251EBBC3A1" > > /* > - * Name: > - * Lenovo_SaveBiosSettings > - * Description: > - * Save any pending changes in settings. > - * Type: > - * Method > - * Arguments: > - * "Password,Encoding,KbdLang;" > - * Example: > - * "pa55w0rd,ascii,us;" > + * Name: SaveBiosSettings > + * Description: Save any pending changes in settings. > + * Type: Method > + * Arguments: "Password,Encoding,KbdLang;" > + * Example: "pa55w0rd,ascii,us;" > */ > #define LENOVO_SAVE_BIOS_SETTINGS_GUID "6A4B54EF-A5ED-4D33-9455-B0D9B48DF4B3" > > /* > - * Name: > - * Lenovo_BiosPasswordSettings > - * Description: > - * Return BIOS Password settings > - * Type: > - * Query > - * Returns: > - * PasswordMode, PasswordState, MinLength, MaxLength, > + * Name: BiosPasswordSettings > + * Description: Return BIOS Password settings > + * Type: Query > + * Returns: PasswordMode, PasswordState, MinLength, MaxLength, > * SupportedEncoding, SupportedKeyboard > */ > #define LENOVO_BIOS_PASSWORD_SETTINGS_GUID "8ADB159E-1E32-455C-BC93-308A7ED98246" > > /* > - * Name: > - * Lenovo_SetBiosPassword > - * Description: > - * Change a specific password. > + * Name: SetBiosPassword > + * Description: Change a specific password. > * - BIOS settings cannot be changed at the same boot as power-on > * passwords (POP) and hard disk passwords (HDP). If you want to change > * BIOS settings and POP or HDP, you must reboot the system after changing > * one of them. > * - A password cannot be set using this method when one does not already > * exist. Passwords can only be updated or cleared. > - * Type: > - * Method > - * Arguments: > - * "PasswordType,CurrentPassword,NewPassword,Encoding,KbdLang;" > - * Example: > - * "pop,pa55w0rd,newpa55w0rd,ascii,us;” > + * Type: Method > + * Arguments: "PasswordType,CurrentPassword,NewPassword,Encoding,KbdLang;" > + * Example: "pop,pa55w0rd,newpa55w0rd,ascii,us;” > */ > #define LENOVO_SET_BIOS_PASSWORD_GUID "2651D9FD-911C-4B69-B94E-D0DED5963BD7" > > /* > - * Name: > - * Lenovo_GetBiosSelections > - * Description: > - * Return a list of valid settings for a given item. > - * Type: > - * Method > - * Arguments: > - * "Item" > - * Returns: > - * "Value1,Value2,Value3,..." > + * Name: GetBiosSelections > + * Description: Return a list of valid settings for a given item. > + * Type: Method > + * Arguments: "Item" > + * Returns: "Value1,Value2,Value3,..." > * Example: > * -> "FlashOverLAN" > * <- "Enabled,Disabled" > @@ -121,18 +93,14 @@ MODULE_PARM_DESC(debug_support, "Enable debug command support"); > #define LENOVO_GET_BIOS_SELECTIONS_GUID "7364651A-132F-4FE7-ADAA-40C6C7EE2E3B" > > /* > - * Name: > - * Lenovo_DebugCmdGUID > - * Description > - * Debug entry GUID method for entering debug commands to the BIOS > + * Name: DebugCmd > + * Description: Debug entry method for entering debug commands to the BIOS > */ > #define LENOVO_DEBUG_CMD_GUID "7FF47003-3B6C-4E5E-A227-E979824A85D1" > > /* > - * Name: > - * Lenovo_OpcodeIF > - * Description: > - * Opcode interface which provides the ability to set multiple > + * Name: OpcodeIF > + * Description: Opcode interface which provides the ability to set multiple > * parameters and then trigger an action with a final command. > * This is particularly useful for simplifying setting passwords. > * With this support comes the ability to set System, HDD and NVMe > @@ -141,10 +109,71 @@ MODULE_PARM_DESC(debug_support, "Enable debug command support"); > */ > #define LENOVO_OPCODE_IF_GUID "DFDDEF2C-57D4-48ce-B196-0FB787D90836" > > +/* > + * Name: SetBiosCert > + * Description: Install BIOS certificate. > + * Type: Method > + * Arguments: "Certificate,Password" > + * You must reboot the computer before the changes will take effect. > + */ > +#define LENOVO_SET_BIOS_CERT_GUID "26861C9F-47E9-44C4-BD8B-DFE7FA2610FE" > + > +/* > + * Name: UpdateBiosCert > + * Description: Update BIOS certificate. > + * Type: Method > + * Format: "Certificate,Signature" > + * You must reboot the computer before the changes will take effect. > + */ > +#define LENOVO_UPDATE_BIOS_CERT_GUID "9AA3180A-9750-41F7-B9F7-D5D3B1BAC3CE" > + > +/* > + * Name: ClearBiosCert > + * Description: Uninstall BIOS certificate. > + * Type: Method > + * Format: "Serial,Signature" > + * You must reboot the computer before the changes will take effect. > + */ > +#define LENOVO_CLEAR_BIOS_CERT_GUID "B2BC39A7-78DD-4D71-B059-A510DEC44890" > +/* > + * Name: CertToPassword > + * Description: Switch from certificate to password authentication. > + * Type: Method > + * Format: "Password,Signature" > + * You must reboot the computer before the changes will take effect. > + */ > +#define LENOVO_CERT_TO_PASSWORD_GUID "0DE8590D-5510-4044-9621-77C227F5A70D" > + > +/* > + * Name: SetBiosSettingCert > + * Description: Set attribute using certificate authentication. > + * Type: Method > + * Format: "Item,Value,Signature" > + */ > +#define LENOVO_SET_BIOS_SETTING_CERT_GUID "34A008CC-D205-4B62-9E67-31DFA8B90003" > + > +/* > + * Name: SaveBiosSettingCert > + * Description: Save any pending changes in settings. > + * Type: Method > + * Format: "Signature" > + */ > +#define LENOVO_SAVE_BIOS_SETTING_CERT_GUID "C050FB9D-DF5F-4606-B066-9EFC401B2551" > + > +/* > + * Name: CertThumbprint > + * Description: Display Certificate thumbprints > + * Type: Query > + * Returns: MD5, SHA1 & SHA256 thumbprints > + */ > +#define LENOVO_CERT_THUMBPRINT_GUID "C59119ED-1C0D-4806-A8E9-59AA318176C4" > + > #define TLMI_POP_PWD (1 << 0) > #define TLMI_PAP_PWD (1 << 1) > #define TLMI_HDD_PWD (1 << 2) > #define TLMI_SYS_PWD (1 << 3) > +#define TLMI_CERT (1 << 7) > + > #define to_tlmi_pwd_setting(kobj) container_of(kobj, struct tlmi_pwd_setting, kobj) > #define to_tlmi_attr_setting(kobj) container_of(kobj, struct tlmi_attr_setting, kobj) > > @@ -168,6 +197,13 @@ static struct think_lmi tlmi_priv; > static struct class *fw_attr_class; > > /* ------ Utility functions ------------*/ > +/* Strip out CR if one is present */ > +static void strip_cr(char *str) > +{ > + char *p = strchrnul(str, '\n'); > + *p = '\0'; > +} > + > /* Convert BIOS WMI error string to suitable error code */ > static int tlmi_errstr_to_err(const char *errstr) > { > @@ -365,7 +401,6 @@ static ssize_t current_password_store(struct kobject *kobj, > { > struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj); > size_t pwdlen; > - char *p; > > pwdlen = strlen(buf); > /* pwdlen == 0 is allowed to clear the password */ > @@ -374,8 +409,7 @@ static ssize_t current_password_store(struct kobject *kobj, > > strscpy(setting->password, buf, setting->maxlen); > /* Strip out CR if one is present, setting password won't work if it is present */ > - p = strchrnul(setting->password, '\n'); > - *p = '\0'; > + strip_cr(setting->password); > return count; > } > > @@ -386,7 +420,7 @@ static ssize_t new_password_store(struct kobject *kobj, > const char *buf, size_t count) > { > struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj); > - char *auth_str, *new_pwd, *p; > + char *auth_str, *new_pwd; > size_t pwdlen; > int ret; > > @@ -401,8 +435,7 @@ static ssize_t new_password_store(struct kobject *kobj, > return -ENOMEM; > > /* Strip out CR if one is present, setting password won't work if it is present */ > - p = strchrnul(new_pwd, '\n'); > - *p = '\0'; > + strip_cr(new_pwd); > > pwdlen = strlen(new_pwd); > /* pwdlen == 0 is allowed to clear the password */ > @@ -608,18 +641,297 @@ static ssize_t level_store(struct kobject *kobj, > > static struct kobj_attribute auth_level = __ATTR_RW(level); > > +static ssize_t cert_thumbprint(char *buf, const char *arg, int count) > +{ > + const struct acpi_buffer input = { strlen(arg), (char *)arg }; > + struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL }; > + const union acpi_object *obj; > + acpi_status status; > + > + status = wmi_evaluate_method(LENOVO_CERT_THUMBPRINT_GUID, 0, 0, &input, &output); > + if (ACPI_FAILURE(status)) { > + kfree(output.pointer); > + return -EIO; > + } > + obj = output.pointer; > + if (!obj) > + return -ENOMEM; > + if (obj->type != ACPI_TYPE_STRING || !obj->string.pointer) { > + kfree(output.pointer); > + return -EIO; > + } > + count += sysfs_emit_at(buf, count, "%s : %s\n", arg, (char *)obj->string.pointer); > + kfree(output.pointer); > + > + return count; > +} > + > +static ssize_t certificate_thumbprint_show(struct kobject *kobj, struct kobj_attribute *attr, > + char *buf) > +{ > + struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj); > + int count = 0; > + > + if (!tlmi_priv.certificate_support || !setting->cert_installed) > + return -EOPNOTSUPP; > + > + count += cert_thumbprint(buf, "Md5", count); > + count += cert_thumbprint(buf, "Sha1", count); > + count += cert_thumbprint(buf, "Sha256", count); > + return count; > +} > + > +static struct kobj_attribute auth_cert_thumb = __ATTR_RO(certificate_thumbprint); > + > +static ssize_t cert_to_password_store(struct kobject *kobj, > + struct kobj_attribute *attr, > + const char *buf, size_t count) > +{ > + struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj); > + char *auth_str, *passwd; > + int ret; > + > + if (!capable(CAP_SYS_ADMIN)) > + return -EPERM; > + > + if (!tlmi_priv.certificate_support) > + return -EOPNOTSUPP; > + > + if (!setting->cert_installed) > + return -EINVAL; > + > + if (!setting->signature || !setting->signature[0]) > + return -EACCES; > + > + passwd = kstrdup(buf, GFP_KERNEL); > + if (!passwd) > + return -ENOMEM; > + > + /* Strip out CR if one is present */ > + strip_cr(passwd); > + > + /* Format: 'Password,Signature' */ > + auth_str = kasprintf(GFP_KERNEL, "%s,%s", passwd, setting->signature); > + if (!auth_str) { > + kfree(passwd); > + return -ENOMEM; > + } > + ret = tlmi_simple_call(LENOVO_CERT_TO_PASSWORD_GUID, auth_str); > + kfree(auth_str); > + kfree(passwd); > + > + return ret ?: count; > +} > + > +static struct kobj_attribute auth_cert_to_password = __ATTR_WO(cert_to_password); > + > +static ssize_t certificate_store(struct kobject *kobj, > + struct kobj_attribute *attr, > + const char *buf, size_t count) > +{ > + struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj); > + char *auth_str, *new_cert; > + int ret; > + > + if (!capable(CAP_SYS_ADMIN)) > + return -EPERM; > + > + if (!tlmi_priv.certificate_support) > + return -EOPNOTSUPP; > + > + new_cert = kstrdup(buf, GFP_KERNEL); > + if (!new_cert) > + return -ENOMEM; > + /* Strip out CR if one is present */ > + strip_cr(new_cert); > + > + /* If empty then clear installed certificate */ > + if (new_cert[0] == '\0') { /* Clear installed certificate */ > + kfree(new_cert); > + > + /* Check that signature is set */ > + if (!setting->signature || !setting->signature[0]) > + return -EACCES; > + > + /* Format: 'serial#, signature' */ > + auth_str = kasprintf(GFP_KERNEL, "%s,%s", > + dmi_get_system_info(DMI_PRODUCT_SERIAL), > + setting->signature); > + if (!auth_str) > + return -ENOMEM; > + > + ret = tlmi_simple_call(LENOVO_CLEAR_BIOS_CERT_GUID, auth_str); > + kfree(auth_str); > + if (ret) > + return ret; > + > + kfree(setting->certificate); > + setting->certificate = NULL; > + return count; > + } > + > + if (setting->cert_installed) { > + /* Certificate is installed so this is an update */ > + if (!setting->signature || !setting->signature[0]) { > + kfree(new_cert); > + return -EACCES; > + } > + /* Format: 'Certificate,Signature' */ > + auth_str = kasprintf(GFP_KERNEL, "%s,%s", > + new_cert, setting->signature); The block starting here. > + if (!auth_str) { > + kfree(new_cert); > + return -ENOMEM; > + } > + ret = tlmi_simple_call(LENOVO_UPDATE_BIOS_CERT_GUID, auth_str); > + kfree(auth_str); And ending here, is identical in the if and else paths with the exception of the guid. > + } else { > + /* This is a fresh install */ > + if (!setting->valid || !setting->password[0]) { > + kfree(new_cert); > + return -EACCES; > + } > + /* Format: 'Certificate,Admin-password' */ > + auth_str = kasprintf(GFP_KERNEL, "%s,%s", > + new_cert, setting->password); > + if (!auth_str) { > + kfree(new_cert); > + return -ENOMEM; > + } > + ret = tlmi_simple_call(LENOVO_SET_BIOS_CERT_GUID, auth_str); > + kfree(auth_str); > + } > + > + /* If successful update stored certificate */ This comment looks weird with it being placed above the error check + return and the code really is self explanatory, please drop it. > + if (ret) { > + kfree(new_cert); > + return ret; > + } > + Together with the if/else refactoring we then get: if (setting->cert_installed) { /* Certificate is installed so this is an update */ if (!setting->signature || !setting->signature[0]) { kfree(new_cert); return -EACCES; } guid = LENOVO_UPDATE_BIOS_CERT_GUID; /* Format: 'Certificate,Signature' */ auth_str = kasprintf(GFP_KERNEL, "%s,%s", new_cert, setting->signature); } else { /* This is a fresh install */ if (!setting->valid || !setting->password[0]) { kfree(new_cert); return -EACCES; } guid = LENOVO_SET_BIOS_CERT_GUID; /* Format: 'Certificate,Admin-password' */ auth_str = kasprintf(GFP_KERNEL, "%s,%s", new_cert, setting->password); } if (!auth_str) { kfree(new_cert); return -ENOMEM; } ret = tlmi_simple_call(LENOVO_UPDATE_BIOS_CERT_GUID, auth_str); kfree(auth_str); if (ret) { kfree(new_cert); return ret; } > + kfree(setting->certificate); > + setting->certificate = new_cert; > + return count; > +} > + > +static ssize_t certificate_show(struct kobject *kobj, struct kobj_attribute *attr, > + char *buf) > +{ > + struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj); > + > + if (!setting->certificate) > + return sysfs_emit(buf, "Not set\n"); > + > + return sysfs_emit(buf, "%s\n", setting->certificate); > +} > + > +static struct kobj_attribute auth_certificate = __ATTR_RW(certificate); > + > +static ssize_t signature_store(struct kobject *kobj, > + struct kobj_attribute *attr, > + const char *buf, size_t count) > +{ > + struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj); > + char *new_signature; > + int ret; > + > + if (!capable(CAP_SYS_ADMIN)) > + return -EPERM; > + > + if (!tlmi_priv.certificate_support) > + return -EOPNOTSUPP; > + > + new_signature = kstrdup(buf, GFP_KERNEL); > + if (!new_signature) > + return -ENOMEM; > + > + /* Strip out CR if one is present */ > + strip_cr(new_signature); > + > + /* Free any previous signature */ > + kfree(setting->signature); > + setting->signature = new_signature; > + > + return ret ?: count; > +} > + > +static ssize_t signature_show(struct kobject *kobj, struct kobj_attribute *attr, > + char *buf) > +{ > + struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj); > + > + if (!setting->signature) > + return sysfs_emit(buf, "Not set\n"); > + > + return sysfs_emit(buf, "%s\n", setting->signature); > +} > + > +static struct kobj_attribute auth_signature = __ATTR_RW(signature); So thinking about this more, having a show function at all is a bad idea, that will allow an attacker to potentially steal the signature. I guess that the signature is specific to the setting being changed, but this will still allow a replay attack, to restore a setting which an attacker has seen being changed in the past. E.g. the admin enables USB ports for some debugging and then disables them again, now an attacker who was able to read the signature file while the admin was enableing the USB ports might re-enable them later. So it would be best to just make this __ATR_WO and not have a show function at all, like we do for the password. > + > +static ssize_t save_signature_store(struct kobject *kobj, > + struct kobj_attribute *attr, > + const char *buf, size_t count) > +{ > + struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj); > + char *new_signature; > + int ret; > + > + if (!capable(CAP_SYS_ADMIN)) > + return -EPERM; > + > + if (!tlmi_priv.certificate_support) > + return -EOPNOTSUPP; > + > + new_signature = kstrdup(buf, GFP_KERNEL); > + if (!new_signature) > + return -ENOMEM; > + > + /* Strip out CR if one is present */ > + strip_cr(new_signature); > + > + /* Free any previous signature */ > + kfree(setting->save_signature); > + setting->save_signature = new_signature; > + > + return ret ?: count; > +} > + > +static ssize_t save_signature_show(struct kobject *kobj, struct kobj_attribute *attr, > + char *buf) > +{ > + struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj); > + > + if (!setting->save_signature) > + return sysfs_emit(buf, "Not set\n"); > + > + return sysfs_emit(buf, "%s\n", setting->save_signature); > +} > + > +static struct kobj_attribute auth_save_signature = __ATTR_RW(save_signature); idem, make this __ATTR_WO too. > + > static umode_t auth_attr_is_visible(struct kobject *kobj, > struct attribute *attr, int n) > { > struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj); > > - /*We only want to display level and index settings on HDD/NVMe */ > + /* We only want to display level and index settings on HDD/NVMe */ > if ((attr == (struct attribute *)&auth_index) || > (attr == (struct attribute *)&auth_level)) { > if ((setting == tlmi_priv.pwd_hdd) || (setting == tlmi_priv.pwd_nvme)) > return attr->mode; > return 0; > } > + > + /* We only display certificates on Admin account, if supported */ > + if ((attr == (struct attribute *)&auth_certificate) || > + (attr == (struct attribute *)&auth_signature) || > + (attr == (struct attribute *)&auth_save_signature) || > + (attr == (struct attribute *)&auth_cert_thumb) || > + (attr == (struct attribute *)&auth_cert_to_password)) { > + if ((setting == tlmi_priv.pwd_admin) && tlmi_priv.certificate_support) > + return attr->mode; > + return 0; > + } > + > return attr->mode; > } > > @@ -635,6 +947,11 @@ static struct attribute *auth_attrs[] = { > &auth_kbdlang.attr, > &auth_index.attr, > &auth_level.attr, > + &auth_certificate.attr, > + &auth_signature.attr, > + &auth_save_signature.attr, > + &auth_cert_thumb.attr, > + &auth_cert_to_password.attr, > NULL > }; > > @@ -689,7 +1006,6 @@ static ssize_t current_value_store(struct kobject *kobj, > struct tlmi_attr_setting *setting = to_tlmi_attr_setting(kobj); > char *set_str = NULL, *new_setting = NULL; > char *auth_str = NULL; > - char *p; > int ret; > > if (!tlmi_priv.can_set_bios_settings) > @@ -700,40 +1016,60 @@ static ssize_t current_value_store(struct kobject *kobj, > return -ENOMEM; > > /* Strip out CR if one is present */ > - p = strchrnul(new_setting, '\n'); > - *p = '\0'; > + strip_cr(new_setting); > > - if (tlmi_priv.pwd_admin->valid && tlmi_priv.pwd_admin->password[0]) { > - auth_str = kasprintf(GFP_KERNEL, "%s,%s,%s;", > - tlmi_priv.pwd_admin->password, > - encoding_options[tlmi_priv.pwd_admin->encoding], > - tlmi_priv.pwd_admin->kbdlang); > - if (!auth_str) { > + /* Check if certificate authentication is enabled and active */ > + if (tlmi_priv.certificate_support && tlmi_priv.pwd_admin->cert_installed) { > + if (!tlmi_priv.pwd_admin->signature || !tlmi_priv.pwd_admin->save_signature) { > + ret = -EINVAL; > + goto out; > + } > + set_str = kasprintf(GFP_KERNEL, "%s,%s,%s", setting->display_name, > + new_setting, tlmi_priv.pwd_admin->signature); > + if (!set_str) { > ret = -ENOMEM; > goto out; > } > - } > > - if (auth_str) > - set_str = kasprintf(GFP_KERNEL, "%s,%s,%s", setting->display_name, > - new_setting, auth_str); > - else > - set_str = kasprintf(GFP_KERNEL, "%s,%s;", setting->display_name, > - new_setting); > - if (!set_str) { > - ret = -ENOMEM; > - goto out; > - } > + ret = tlmi_simple_call(LENOVO_SET_BIOS_SETTING_CERT_GUID, set_str); > + if (ret) > + goto out; > + ret = tlmi_simple_call(LENOVO_SAVE_BIOS_SETTING_CERT_GUID, > + tlmi_priv.pwd_admin->save_signature); > + if (ret) > + goto out; > + } else { /* Non certiifcate based authentication */ > + if (tlmi_priv.pwd_admin->valid && tlmi_priv.pwd_admin->password[0]) { > + auth_str = kasprintf(GFP_KERNEL, "%s,%s,%s;", > + tlmi_priv.pwd_admin->password, > + encoding_options[tlmi_priv.pwd_admin->encoding], > + tlmi_priv.pwd_admin->kbdlang); > + if (!auth_str) { > + ret = -ENOMEM; > + goto out; > + } > + } > > - ret = tlmi_simple_call(LENOVO_SET_BIOS_SETTINGS_GUID, set_str); > - if (ret) > - goto out; > + if (auth_str) > + set_str = kasprintf(GFP_KERNEL, "%s,%s,%s", setting->display_name, > + new_setting, auth_str); > + else > + set_str = kasprintf(GFP_KERNEL, "%s,%s;", setting->display_name, > + new_setting); > + if (!set_str) { > + ret = -ENOMEM; > + goto out; > + } > > - if (auth_str) > - ret = tlmi_save_bios_settings(auth_str); > - else > - ret = tlmi_save_bios_settings(""); > + ret = tlmi_simple_call(LENOVO_SET_BIOS_SETTINGS_GUID, set_str); > + if (ret) > + goto out; > > + if (auth_str) > + ret = tlmi_save_bios_settings(auth_str); > + else > + ret = tlmi_save_bios_settings(""); > + } > if (!ret && !tlmi_priv.pending_changes) { > tlmi_priv.pending_changes = true; > /* let userland know it may need to check reboot pending again */ > @@ -829,7 +1165,6 @@ static ssize_t debug_cmd_store(struct kobject *kobj, struct kobj_attribute *attr > { > char *set_str = NULL, *new_setting = NULL; > char *auth_str = NULL; > - char *p; > int ret; > > if (!tlmi_priv.can_debug_cmd) > @@ -840,8 +1175,7 @@ static ssize_t debug_cmd_store(struct kobject *kobj, struct kobj_attribute *attr > return -ENOMEM; > > /* Strip out CR if one is present */ > - p = strchrnul(new_setting, '\n'); > - *p = '\0'; > + strip_cr(new_setting); > > if (tlmi_priv.pwd_admin->valid && tlmi_priv.pwd_admin->password[0]) { > auth_str = kasprintf(GFP_KERNEL, "%s,%s,%s;", > @@ -896,8 +1230,15 @@ static void tlmi_release_attr(void) > sysfs_remove_file(&tlmi_priv.attribute_kset->kobj, &pending_reboot.attr); > if (tlmi_priv.can_debug_cmd && debug_support) > sysfs_remove_file(&tlmi_priv.attribute_kset->kobj, &debug_cmd.attr); > + > kset_unregister(tlmi_priv.attribute_kset); > > + if (tlmi_priv.certificate_support) { > + kfree(tlmi_priv.pwd_admin->certificate); > + kfree(tlmi_priv.pwd_admin->signature); > + kfree(tlmi_priv.pwd_admin->save_signature); > + } > + 1. These kfree() calls should be done only after removing the sysfs group, otherwise here is a race where the could still be accessed after being free-ed 2. kfree(NULL) is a no-op so the "if (tlmi_priv.certificate_support)" check is not necessary. > /* Authentication structures */ > sysfs_remove_group(&tlmi_priv.pwd_admin->kobj, &auth_attr_group); > kobject_put(&tlmi_priv.pwd_admin->kobj); > @@ -975,6 +1316,7 @@ static int tlmi_sysfs_init(void) > if (ret) > goto fail_create_attr; > } > + > /* Create authentication entries */ > tlmi_priv.authentication_kset = kset_create_and_add("authentication", NULL, > &tlmi_priv.class_dev->kobj); > @@ -1087,6 +1429,11 @@ static int tlmi_analyze(void) > if (wmi_has_guid(LENOVO_OPCODE_IF_GUID)) > tlmi_priv.opcode_support = true; > > + if (wmi_has_guid(LENOVO_SET_BIOS_CERT_GUID) && > + wmi_has_guid(LENOVO_SET_BIOS_SETTING_CERT_GUID) && > + wmi_has_guid(LENOVO_SAVE_BIOS_SETTING_CERT_GUID)) > + tlmi_priv.certificate_support = true; > + > /* > * Try to find the number of valid settings of this machine > * and use it to create sysfs attributes. > @@ -1198,6 +1545,11 @@ static int tlmi_analyze(void) > } > } > } > + > + if (tlmi_priv.certificate_support && > + (tlmi_priv.pwdcfg.core.password_state & TLMI_CERT)) > + tlmi_priv.pwd_admin->cert_installed = true; > + > return 0; > > fail_clear_attr: > diff --git a/drivers/platform/x86/think-lmi.h b/drivers/platform/x86/think-lmi.h > index e46c7f383353..4f69df6eed07 100644 > --- a/drivers/platform/x86/think-lmi.h > +++ b/drivers/platform/x86/think-lmi.h > @@ -62,6 +62,10 @@ struct tlmi_pwd_setting { > char kbdlang[TLMI_LANG_MAXLEN]; > int index; /*Used for HDD and NVME auth */ > enum level_option level; > + bool cert_installed; > + char *certificate; > + char *signature; > + char *save_signature; > }; > > /* Attribute setting details */ > @@ -82,6 +86,7 @@ struct think_lmi { > bool pending_changes; > bool can_debug_cmd; > bool opcode_support; > + bool certificate_support; > > struct tlmi_attr_setting *setting[TLMI_SETTINGS_COUNT]; > struct device *class_dev; Regards, Hans
Thanks Hans On 2022-03-17 07:21, Hans de Goede wrote: > Hi Mark, > > On 3/15/22 20:56, Mark Pearson wrote: >> Implementation of certificate authentication feature for Lenovo >> platforms. This allows for signed updates of BIOS settings. >> >> Functionality supported: >> - Cert support available check. At initialisation check if BIOS >> supports certification authentication and if a certificate is >> installed. Enable the sysfs nodes appropriately >> - certificate and signature authentication attributes to enable >> a user to install, update and delete a certificate using signed >> signatures >> - certificate_thumbprint to confirm installed certificate details >> - support to go from certificate to password based authentication >> - signature and save_signature attributes needed for setting BIOS >> attributes using certificate authentication. >> >> Tested on X1 Carbon 10 with special trial BIOS. This feature is not >> generally available yet but will be released later this year. >> >> Note, I also cleaned up the formating of the GUIDs when I was adding >> the new defines. Hope that's OK to combine in this commit. >> >> Signed-off-by: Mark Pearson <markpearson@lenovo.com> >> --- >> Changes in v2: >> - Combined set_signature with signature and moved save_signature under >> the authorisation folder >> - utility function to strip CR from string >> - Clean up code as recommended from review > > Thanks this is looking better now, I still have a few small > remarks, see below. > >> >> drivers/platform/x86/think-lmi.c | 560 +++++++++++++++++++++++++------ >> drivers/platform/x86/think-lmi.h | 5 + >> 2 files changed, 461 insertions(+), 104 deletions(-) >> >> diff --git a/drivers/platform/x86/think-lmi.c b/drivers/platform/x86/think-lmi.c >> index 0b73e16cccea..1db34a6c94c2 100644 >> --- a/drivers/platform/x86/think-lmi.c >> +++ b/drivers/platform/x86/think-lmi.c >> @@ -16,6 +16,7 @@ <snip> >> + >> + if (setting->cert_installed) { >> + /* Certificate is installed so this is an update */ >> + if (!setting->signature || !setting->signature[0]) { >> + kfree(new_cert); >> + return -EACCES; >> + } >> + /* Format: 'Certificate,Signature' */ >> + auth_str = kasprintf(GFP_KERNEL, "%s,%s", >> + new_cert, setting->signature); > > The block starting here. > >> + if (!auth_str) { >> + kfree(new_cert); >> + return -ENOMEM; >> + } >> + ret = tlmi_simple_call(LENOVO_UPDATE_BIOS_CERT_GUID, auth_str); >> + kfree(auth_str); > > And ending here, is identical in the if and else paths with the > exception of the guid. > >> + } else { >> + /* This is a fresh install */ >> + if (!setting->valid || !setting->password[0]) { >> + kfree(new_cert); >> + return -EACCES; >> + } >> + /* Format: 'Certificate,Admin-password' */ >> + auth_str = kasprintf(GFP_KERNEL, "%s,%s", >> + new_cert, setting->password); >> + if (!auth_str) { >> + kfree(new_cert); >> + return -ENOMEM; >> + } >> + ret = tlmi_simple_call(LENOVO_SET_BIOS_CERT_GUID, auth_str); >> + kfree(auth_str); >> + } >> + >> + /* If successful update stored certificate */ > > This comment looks weird with it being placed above the error check + return and > the code really is self explanatory, please drop it. > >> + if (ret) { >> + kfree(new_cert); >> + return ret; >> + } >> + > > Together with the if/else refactoring we then get: > > if (setting->cert_installed) { > /* Certificate is installed so this is an update */ > if (!setting->signature || !setting->signature[0]) { > kfree(new_cert); > return -EACCES; > } > guid = LENOVO_UPDATE_BIOS_CERT_GUID; > /* Format: 'Certificate,Signature' */ > auth_str = kasprintf(GFP_KERNEL, "%s,%s", > new_cert, setting->signature); > } else { > /* This is a fresh install */ > if (!setting->valid || !setting->password[0]) { > kfree(new_cert); > return -EACCES; > } > guid = LENOVO_SET_BIOS_CERT_GUID; > /* Format: 'Certificate,Admin-password' */ > auth_str = kasprintf(GFP_KERNEL, "%s,%s", > new_cert, setting->password); > } > if (!auth_str) { > kfree(new_cert); > return -ENOMEM; > } > > ret = tlmi_simple_call(LENOVO_UPDATE_BIOS_CERT_GUID, auth_str); > kfree(auth_str); > if (ret) { > kfree(new_cert); > return ret; > } > Agreed - much nicer. I'll get that implemented >> + kfree(setting->certificate); >> + setting->certificate = new_cert; >> + return count; >> +} >> + <snip> >> + >> +static ssize_t signature_show(struct kobject *kobj, struct kobj_attribute *attr, >> + char *buf) >> +{ >> + struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj); >> + >> + if (!setting->signature) >> + return sysfs_emit(buf, "Not set\n"); >> + >> + return sysfs_emit(buf, "%s\n", setting->signature); >> +} >> + >> +static struct kobj_attribute auth_signature = __ATTR_RW(signature); > > So thinking about this more, having a show function at all is a bad > idea, that will allow an attacker to potentially steal the signature. > > I guess that the signature is specific to the setting being changed, > but this will still allow a replay attack, to restore a setting which > an attacker has seen being changed in the past. E.g. the admin > enables USB ports for some debugging and then disables them again, > now an attacker who was able to read the signature file while the > admin was enableing the USB ports might re-enable them later. > > So it would be best to just make this __ATR_WO and not have > a show function at all, like we do for the password. > Fair enough. I'm good to remove it. > > >> + >> +static ssize_t save_signature_store(struct kobject *kobj, >> + struct kobj_attribute *attr, >> + const char *buf, size_t count) >> +{ >> + struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj); >> + char *new_signature; >> + int ret; >> + >> + if (!capable(CAP_SYS_ADMIN)) >> + return -EPERM; >> + >> + if (!tlmi_priv.certificate_support) >> + return -EOPNOTSUPP; >> + >> + new_signature = kstrdup(buf, GFP_KERNEL); >> + if (!new_signature) >> + return -ENOMEM; >> + >> + /* Strip out CR if one is present */ >> + strip_cr(new_signature); >> + >> + /* Free any previous signature */ >> + kfree(setting->save_signature); >> + setting->save_signature = new_signature; >> + >> + return ret ?: count; >> +} >> + >> +static ssize_t save_signature_show(struct kobject *kobj, struct kobj_attribute *attr, >> + char *buf) >> +{ >> + struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj); >> + >> + if (!setting->save_signature) >> + return sysfs_emit(buf, "Not set\n"); >> + >> + return sysfs_emit(buf, "%s\n", setting->save_signature); >> +} >> + >> +static struct kobj_attribute auth_save_signature = __ATTR_RW(save_signature); > > idem, make this __ATTR_WO too. ack > <snip> >> @@ -896,8 +1230,15 @@ static void tlmi_release_attr(void) >> sysfs_remove_file(&tlmi_priv.attribute_kset->kobj, &pending_reboot.attr); >> if (tlmi_priv.can_debug_cmd && debug_support) >> sysfs_remove_file(&tlmi_priv.attribute_kset->kobj, &debug_cmd.attr); >> + >> kset_unregister(tlmi_priv.attribute_kset); >> >> + if (tlmi_priv.certificate_support) { >> + kfree(tlmi_priv.pwd_admin->certificate); >> + kfree(tlmi_priv.pwd_admin->signature); >> + kfree(tlmi_priv.pwd_admin->save_signature); >> + } >> + > > 1. These kfree() calls should be done only after removing the > sysfs group, otherwise here is a race where the could still > be accessed after being free-ed > > 2. kfree(NULL) is a no-op so the "if (tlmi_priv.certificate_support)" > check is not necessary. Ack - I'll fix these. Thanks for the review Mark
diff --git a/drivers/platform/x86/think-lmi.c b/drivers/platform/x86/think-lmi.c index 0b73e16cccea..1db34a6c94c2 100644 --- a/drivers/platform/x86/think-lmi.c +++ b/drivers/platform/x86/think-lmi.c @@ -16,6 +16,7 @@ #include <linux/fs.h> #include <linux/string.h> #include <linux/types.h> +#include <linux/dmi.h> #include <linux/wmi.h> #include "firmware_attributes_class.h" #include "think-lmi.h" @@ -25,95 +26,66 @@ module_param(debug_support, bool, 0444); MODULE_PARM_DESC(debug_support, "Enable debug command support"); /* - * Name: - * Lenovo_BiosSetting - * Description: - * Get item name and settings for current LMI instance. - * Type: - * Query - * Returns: - * "Item,Value" - * Example: - * "WakeOnLAN,Enable" + * Name: BiosSetting + * Description: Get item name and settings for current LMI instance. + * Type: Query + * Returns: "Item,Value" + * Example: "WakeOnLAN,Enable" */ #define LENOVO_BIOS_SETTING_GUID "51F5230E-9677-46CD-A1CF-C0B23EE34DB7" /* - * Name: - * Lenovo_SetBiosSetting - * Description: - * Change the BIOS setting to the desired value using the Lenovo_SetBiosSetting - * class. To save the settings, use the Lenovo_SaveBiosSetting class. + * Name: SetBiosSetting + * Description: Change the BIOS setting to the desired value using the SetBiosSetting + * class. To save the settings, use the SaveBiosSetting class. * BIOS settings and values are case sensitive. * After making changes to the BIOS settings, you must reboot the computer * before the changes will take effect. - * Type: - * Method - * Arguments: - * "Item,Value,Password,Encoding,KbdLang;" - * Example: - * "WakeOnLAN,Disable,pa55w0rd,ascii,us;" + * Type: Method + * Arguments: "Item,Value,Password,Encoding,KbdLang;" + * Example: "WakeOnLAN,Disable,pa55w0rd,ascii,us;" */ #define LENOVO_SET_BIOS_SETTINGS_GUID "98479A64-33F5-4E33-A707-8E251EBBC3A1" /* - * Name: - * Lenovo_SaveBiosSettings - * Description: - * Save any pending changes in settings. - * Type: - * Method - * Arguments: - * "Password,Encoding,KbdLang;" - * Example: - * "pa55w0rd,ascii,us;" + * Name: SaveBiosSettings + * Description: Save any pending changes in settings. + * Type: Method + * Arguments: "Password,Encoding,KbdLang;" + * Example: "pa55w0rd,ascii,us;" */ #define LENOVO_SAVE_BIOS_SETTINGS_GUID "6A4B54EF-A5ED-4D33-9455-B0D9B48DF4B3" /* - * Name: - * Lenovo_BiosPasswordSettings - * Description: - * Return BIOS Password settings - * Type: - * Query - * Returns: - * PasswordMode, PasswordState, MinLength, MaxLength, + * Name: BiosPasswordSettings + * Description: Return BIOS Password settings + * Type: Query + * Returns: PasswordMode, PasswordState, MinLength, MaxLength, * SupportedEncoding, SupportedKeyboard */ #define LENOVO_BIOS_PASSWORD_SETTINGS_GUID "8ADB159E-1E32-455C-BC93-308A7ED98246" /* - * Name: - * Lenovo_SetBiosPassword - * Description: - * Change a specific password. + * Name: SetBiosPassword + * Description: Change a specific password. * - BIOS settings cannot be changed at the same boot as power-on * passwords (POP) and hard disk passwords (HDP). If you want to change * BIOS settings and POP or HDP, you must reboot the system after changing * one of them. * - A password cannot be set using this method when one does not already * exist. Passwords can only be updated or cleared. - * Type: - * Method - * Arguments: - * "PasswordType,CurrentPassword,NewPassword,Encoding,KbdLang;" - * Example: - * "pop,pa55w0rd,newpa55w0rd,ascii,us;” + * Type: Method + * Arguments: "PasswordType,CurrentPassword,NewPassword,Encoding,KbdLang;" + * Example: "pop,pa55w0rd,newpa55w0rd,ascii,us;” */ #define LENOVO_SET_BIOS_PASSWORD_GUID "2651D9FD-911C-4B69-B94E-D0DED5963BD7" /* - * Name: - * Lenovo_GetBiosSelections - * Description: - * Return a list of valid settings for a given item. - * Type: - * Method - * Arguments: - * "Item" - * Returns: - * "Value1,Value2,Value3,..." + * Name: GetBiosSelections + * Description: Return a list of valid settings for a given item. + * Type: Method + * Arguments: "Item" + * Returns: "Value1,Value2,Value3,..." * Example: * -> "FlashOverLAN" * <- "Enabled,Disabled" @@ -121,18 +93,14 @@ MODULE_PARM_DESC(debug_support, "Enable debug command support"); #define LENOVO_GET_BIOS_SELECTIONS_GUID "7364651A-132F-4FE7-ADAA-40C6C7EE2E3B" /* - * Name: - * Lenovo_DebugCmdGUID - * Description - * Debug entry GUID method for entering debug commands to the BIOS + * Name: DebugCmd + * Description: Debug entry method for entering debug commands to the BIOS */ #define LENOVO_DEBUG_CMD_GUID "7FF47003-3B6C-4E5E-A227-E979824A85D1" /* - * Name: - * Lenovo_OpcodeIF - * Description: - * Opcode interface which provides the ability to set multiple + * Name: OpcodeIF + * Description: Opcode interface which provides the ability to set multiple * parameters and then trigger an action with a final command. * This is particularly useful for simplifying setting passwords. * With this support comes the ability to set System, HDD and NVMe @@ -141,10 +109,71 @@ MODULE_PARM_DESC(debug_support, "Enable debug command support"); */ #define LENOVO_OPCODE_IF_GUID "DFDDEF2C-57D4-48ce-B196-0FB787D90836" +/* + * Name: SetBiosCert + * Description: Install BIOS certificate. + * Type: Method + * Arguments: "Certificate,Password" + * You must reboot the computer before the changes will take effect. + */ +#define LENOVO_SET_BIOS_CERT_GUID "26861C9F-47E9-44C4-BD8B-DFE7FA2610FE" + +/* + * Name: UpdateBiosCert + * Description: Update BIOS certificate. + * Type: Method + * Format: "Certificate,Signature" + * You must reboot the computer before the changes will take effect. + */ +#define LENOVO_UPDATE_BIOS_CERT_GUID "9AA3180A-9750-41F7-B9F7-D5D3B1BAC3CE" + +/* + * Name: ClearBiosCert + * Description: Uninstall BIOS certificate. + * Type: Method + * Format: "Serial,Signature" + * You must reboot the computer before the changes will take effect. + */ +#define LENOVO_CLEAR_BIOS_CERT_GUID "B2BC39A7-78DD-4D71-B059-A510DEC44890" +/* + * Name: CertToPassword + * Description: Switch from certificate to password authentication. + * Type: Method + * Format: "Password,Signature" + * You must reboot the computer before the changes will take effect. + */ +#define LENOVO_CERT_TO_PASSWORD_GUID "0DE8590D-5510-4044-9621-77C227F5A70D" + +/* + * Name: SetBiosSettingCert + * Description: Set attribute using certificate authentication. + * Type: Method + * Format: "Item,Value,Signature" + */ +#define LENOVO_SET_BIOS_SETTING_CERT_GUID "34A008CC-D205-4B62-9E67-31DFA8B90003" + +/* + * Name: SaveBiosSettingCert + * Description: Save any pending changes in settings. + * Type: Method + * Format: "Signature" + */ +#define LENOVO_SAVE_BIOS_SETTING_CERT_GUID "C050FB9D-DF5F-4606-B066-9EFC401B2551" + +/* + * Name: CertThumbprint + * Description: Display Certificate thumbprints + * Type: Query + * Returns: MD5, SHA1 & SHA256 thumbprints + */ +#define LENOVO_CERT_THUMBPRINT_GUID "C59119ED-1C0D-4806-A8E9-59AA318176C4" + #define TLMI_POP_PWD (1 << 0) #define TLMI_PAP_PWD (1 << 1) #define TLMI_HDD_PWD (1 << 2) #define TLMI_SYS_PWD (1 << 3) +#define TLMI_CERT (1 << 7) + #define to_tlmi_pwd_setting(kobj) container_of(kobj, struct tlmi_pwd_setting, kobj) #define to_tlmi_attr_setting(kobj) container_of(kobj, struct tlmi_attr_setting, kobj) @@ -168,6 +197,13 @@ static struct think_lmi tlmi_priv; static struct class *fw_attr_class; /* ------ Utility functions ------------*/ +/* Strip out CR if one is present */ +static void strip_cr(char *str) +{ + char *p = strchrnul(str, '\n'); + *p = '\0'; +} + /* Convert BIOS WMI error string to suitable error code */ static int tlmi_errstr_to_err(const char *errstr) { @@ -365,7 +401,6 @@ static ssize_t current_password_store(struct kobject *kobj, { struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj); size_t pwdlen; - char *p; pwdlen = strlen(buf); /* pwdlen == 0 is allowed to clear the password */ @@ -374,8 +409,7 @@ static ssize_t current_password_store(struct kobject *kobj, strscpy(setting->password, buf, setting->maxlen); /* Strip out CR if one is present, setting password won't work if it is present */ - p = strchrnul(setting->password, '\n'); - *p = '\0'; + strip_cr(setting->password); return count; } @@ -386,7 +420,7 @@ static ssize_t new_password_store(struct kobject *kobj, const char *buf, size_t count) { struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj); - char *auth_str, *new_pwd, *p; + char *auth_str, *new_pwd; size_t pwdlen; int ret; @@ -401,8 +435,7 @@ static ssize_t new_password_store(struct kobject *kobj, return -ENOMEM; /* Strip out CR if one is present, setting password won't work if it is present */ - p = strchrnul(new_pwd, '\n'); - *p = '\0'; + strip_cr(new_pwd); pwdlen = strlen(new_pwd); /* pwdlen == 0 is allowed to clear the password */ @@ -608,18 +641,297 @@ static ssize_t level_store(struct kobject *kobj, static struct kobj_attribute auth_level = __ATTR_RW(level); +static ssize_t cert_thumbprint(char *buf, const char *arg, int count) +{ + const struct acpi_buffer input = { strlen(arg), (char *)arg }; + struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL }; + const union acpi_object *obj; + acpi_status status; + + status = wmi_evaluate_method(LENOVO_CERT_THUMBPRINT_GUID, 0, 0, &input, &output); + if (ACPI_FAILURE(status)) { + kfree(output.pointer); + return -EIO; + } + obj = output.pointer; + if (!obj) + return -ENOMEM; + if (obj->type != ACPI_TYPE_STRING || !obj->string.pointer) { + kfree(output.pointer); + return -EIO; + } + count += sysfs_emit_at(buf, count, "%s : %s\n", arg, (char *)obj->string.pointer); + kfree(output.pointer); + + return count; +} + +static ssize_t certificate_thumbprint_show(struct kobject *kobj, struct kobj_attribute *attr, + char *buf) +{ + struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj); + int count = 0; + + if (!tlmi_priv.certificate_support || !setting->cert_installed) + return -EOPNOTSUPP; + + count += cert_thumbprint(buf, "Md5", count); + count += cert_thumbprint(buf, "Sha1", count); + count += cert_thumbprint(buf, "Sha256", count); + return count; +} + +static struct kobj_attribute auth_cert_thumb = __ATTR_RO(certificate_thumbprint); + +static ssize_t cert_to_password_store(struct kobject *kobj, + struct kobj_attribute *attr, + const char *buf, size_t count) +{ + struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj); + char *auth_str, *passwd; + int ret; + + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + if (!tlmi_priv.certificate_support) + return -EOPNOTSUPP; + + if (!setting->cert_installed) + return -EINVAL; + + if (!setting->signature || !setting->signature[0]) + return -EACCES; + + passwd = kstrdup(buf, GFP_KERNEL); + if (!passwd) + return -ENOMEM; + + /* Strip out CR if one is present */ + strip_cr(passwd); + + /* Format: 'Password,Signature' */ + auth_str = kasprintf(GFP_KERNEL, "%s,%s", passwd, setting->signature); + if (!auth_str) { + kfree(passwd); + return -ENOMEM; + } + ret = tlmi_simple_call(LENOVO_CERT_TO_PASSWORD_GUID, auth_str); + kfree(auth_str); + kfree(passwd); + + return ret ?: count; +} + +static struct kobj_attribute auth_cert_to_password = __ATTR_WO(cert_to_password); + +static ssize_t certificate_store(struct kobject *kobj, + struct kobj_attribute *attr, + const char *buf, size_t count) +{ + struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj); + char *auth_str, *new_cert; + int ret; + + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + if (!tlmi_priv.certificate_support) + return -EOPNOTSUPP; + + new_cert = kstrdup(buf, GFP_KERNEL); + if (!new_cert) + return -ENOMEM; + /* Strip out CR if one is present */ + strip_cr(new_cert); + + /* If empty then clear installed certificate */ + if (new_cert[0] == '\0') { /* Clear installed certificate */ + kfree(new_cert); + + /* Check that signature is set */ + if (!setting->signature || !setting->signature[0]) + return -EACCES; + + /* Format: 'serial#, signature' */ + auth_str = kasprintf(GFP_KERNEL, "%s,%s", + dmi_get_system_info(DMI_PRODUCT_SERIAL), + setting->signature); + if (!auth_str) + return -ENOMEM; + + ret = tlmi_simple_call(LENOVO_CLEAR_BIOS_CERT_GUID, auth_str); + kfree(auth_str); + if (ret) + return ret; + + kfree(setting->certificate); + setting->certificate = NULL; + return count; + } + + if (setting->cert_installed) { + /* Certificate is installed so this is an update */ + if (!setting->signature || !setting->signature[0]) { + kfree(new_cert); + return -EACCES; + } + /* Format: 'Certificate,Signature' */ + auth_str = kasprintf(GFP_KERNEL, "%s,%s", + new_cert, setting->signature); + if (!auth_str) { + kfree(new_cert); + return -ENOMEM; + } + ret = tlmi_simple_call(LENOVO_UPDATE_BIOS_CERT_GUID, auth_str); + kfree(auth_str); + } else { + /* This is a fresh install */ + if (!setting->valid || !setting->password[0]) { + kfree(new_cert); + return -EACCES; + } + /* Format: 'Certificate,Admin-password' */ + auth_str = kasprintf(GFP_KERNEL, "%s,%s", + new_cert, setting->password); + if (!auth_str) { + kfree(new_cert); + return -ENOMEM; + } + ret = tlmi_simple_call(LENOVO_SET_BIOS_CERT_GUID, auth_str); + kfree(auth_str); + } + + /* If successful update stored certificate */ + if (ret) { + kfree(new_cert); + return ret; + } + + kfree(setting->certificate); + setting->certificate = new_cert; + return count; +} + +static ssize_t certificate_show(struct kobject *kobj, struct kobj_attribute *attr, + char *buf) +{ + struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj); + + if (!setting->certificate) + return sysfs_emit(buf, "Not set\n"); + + return sysfs_emit(buf, "%s\n", setting->certificate); +} + +static struct kobj_attribute auth_certificate = __ATTR_RW(certificate); + +static ssize_t signature_store(struct kobject *kobj, + struct kobj_attribute *attr, + const char *buf, size_t count) +{ + struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj); + char *new_signature; + int ret; + + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + if (!tlmi_priv.certificate_support) + return -EOPNOTSUPP; + + new_signature = kstrdup(buf, GFP_KERNEL); + if (!new_signature) + return -ENOMEM; + + /* Strip out CR if one is present */ + strip_cr(new_signature); + + /* Free any previous signature */ + kfree(setting->signature); + setting->signature = new_signature; + + return ret ?: count; +} + +static ssize_t signature_show(struct kobject *kobj, struct kobj_attribute *attr, + char *buf) +{ + struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj); + + if (!setting->signature) + return sysfs_emit(buf, "Not set\n"); + + return sysfs_emit(buf, "%s\n", setting->signature); +} + +static struct kobj_attribute auth_signature = __ATTR_RW(signature); + +static ssize_t save_signature_store(struct kobject *kobj, + struct kobj_attribute *attr, + const char *buf, size_t count) +{ + struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj); + char *new_signature; + int ret; + + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + if (!tlmi_priv.certificate_support) + return -EOPNOTSUPP; + + new_signature = kstrdup(buf, GFP_KERNEL); + if (!new_signature) + return -ENOMEM; + + /* Strip out CR if one is present */ + strip_cr(new_signature); + + /* Free any previous signature */ + kfree(setting->save_signature); + setting->save_signature = new_signature; + + return ret ?: count; +} + +static ssize_t save_signature_show(struct kobject *kobj, struct kobj_attribute *attr, + char *buf) +{ + struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj); + + if (!setting->save_signature) + return sysfs_emit(buf, "Not set\n"); + + return sysfs_emit(buf, "%s\n", setting->save_signature); +} + +static struct kobj_attribute auth_save_signature = __ATTR_RW(save_signature); + static umode_t auth_attr_is_visible(struct kobject *kobj, struct attribute *attr, int n) { struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj); - /*We only want to display level and index settings on HDD/NVMe */ + /* We only want to display level and index settings on HDD/NVMe */ if ((attr == (struct attribute *)&auth_index) || (attr == (struct attribute *)&auth_level)) { if ((setting == tlmi_priv.pwd_hdd) || (setting == tlmi_priv.pwd_nvme)) return attr->mode; return 0; } + + /* We only display certificates on Admin account, if supported */ + if ((attr == (struct attribute *)&auth_certificate) || + (attr == (struct attribute *)&auth_signature) || + (attr == (struct attribute *)&auth_save_signature) || + (attr == (struct attribute *)&auth_cert_thumb) || + (attr == (struct attribute *)&auth_cert_to_password)) { + if ((setting == tlmi_priv.pwd_admin) && tlmi_priv.certificate_support) + return attr->mode; + return 0; + } + return attr->mode; } @@ -635,6 +947,11 @@ static struct attribute *auth_attrs[] = { &auth_kbdlang.attr, &auth_index.attr, &auth_level.attr, + &auth_certificate.attr, + &auth_signature.attr, + &auth_save_signature.attr, + &auth_cert_thumb.attr, + &auth_cert_to_password.attr, NULL }; @@ -689,7 +1006,6 @@ static ssize_t current_value_store(struct kobject *kobj, struct tlmi_attr_setting *setting = to_tlmi_attr_setting(kobj); char *set_str = NULL, *new_setting = NULL; char *auth_str = NULL; - char *p; int ret; if (!tlmi_priv.can_set_bios_settings) @@ -700,40 +1016,60 @@ static ssize_t current_value_store(struct kobject *kobj, return -ENOMEM; /* Strip out CR if one is present */ - p = strchrnul(new_setting, '\n'); - *p = '\0'; + strip_cr(new_setting); - if (tlmi_priv.pwd_admin->valid && tlmi_priv.pwd_admin->password[0]) { - auth_str = kasprintf(GFP_KERNEL, "%s,%s,%s;", - tlmi_priv.pwd_admin->password, - encoding_options[tlmi_priv.pwd_admin->encoding], - tlmi_priv.pwd_admin->kbdlang); - if (!auth_str) { + /* Check if certificate authentication is enabled and active */ + if (tlmi_priv.certificate_support && tlmi_priv.pwd_admin->cert_installed) { + if (!tlmi_priv.pwd_admin->signature || !tlmi_priv.pwd_admin->save_signature) { + ret = -EINVAL; + goto out; + } + set_str = kasprintf(GFP_KERNEL, "%s,%s,%s", setting->display_name, + new_setting, tlmi_priv.pwd_admin->signature); + if (!set_str) { ret = -ENOMEM; goto out; } - } - if (auth_str) - set_str = kasprintf(GFP_KERNEL, "%s,%s,%s", setting->display_name, - new_setting, auth_str); - else - set_str = kasprintf(GFP_KERNEL, "%s,%s;", setting->display_name, - new_setting); - if (!set_str) { - ret = -ENOMEM; - goto out; - } + ret = tlmi_simple_call(LENOVO_SET_BIOS_SETTING_CERT_GUID, set_str); + if (ret) + goto out; + ret = tlmi_simple_call(LENOVO_SAVE_BIOS_SETTING_CERT_GUID, + tlmi_priv.pwd_admin->save_signature); + if (ret) + goto out; + } else { /* Non certiifcate based authentication */ + if (tlmi_priv.pwd_admin->valid && tlmi_priv.pwd_admin->password[0]) { + auth_str = kasprintf(GFP_KERNEL, "%s,%s,%s;", + tlmi_priv.pwd_admin->password, + encoding_options[tlmi_priv.pwd_admin->encoding], + tlmi_priv.pwd_admin->kbdlang); + if (!auth_str) { + ret = -ENOMEM; + goto out; + } + } - ret = tlmi_simple_call(LENOVO_SET_BIOS_SETTINGS_GUID, set_str); - if (ret) - goto out; + if (auth_str) + set_str = kasprintf(GFP_KERNEL, "%s,%s,%s", setting->display_name, + new_setting, auth_str); + else + set_str = kasprintf(GFP_KERNEL, "%s,%s;", setting->display_name, + new_setting); + if (!set_str) { + ret = -ENOMEM; + goto out; + } - if (auth_str) - ret = tlmi_save_bios_settings(auth_str); - else - ret = tlmi_save_bios_settings(""); + ret = tlmi_simple_call(LENOVO_SET_BIOS_SETTINGS_GUID, set_str); + if (ret) + goto out; + if (auth_str) + ret = tlmi_save_bios_settings(auth_str); + else + ret = tlmi_save_bios_settings(""); + } if (!ret && !tlmi_priv.pending_changes) { tlmi_priv.pending_changes = true; /* let userland know it may need to check reboot pending again */ @@ -829,7 +1165,6 @@ static ssize_t debug_cmd_store(struct kobject *kobj, struct kobj_attribute *attr { char *set_str = NULL, *new_setting = NULL; char *auth_str = NULL; - char *p; int ret; if (!tlmi_priv.can_debug_cmd) @@ -840,8 +1175,7 @@ static ssize_t debug_cmd_store(struct kobject *kobj, struct kobj_attribute *attr return -ENOMEM; /* Strip out CR if one is present */ - p = strchrnul(new_setting, '\n'); - *p = '\0'; + strip_cr(new_setting); if (tlmi_priv.pwd_admin->valid && tlmi_priv.pwd_admin->password[0]) { auth_str = kasprintf(GFP_KERNEL, "%s,%s,%s;", @@ -896,8 +1230,15 @@ static void tlmi_release_attr(void) sysfs_remove_file(&tlmi_priv.attribute_kset->kobj, &pending_reboot.attr); if (tlmi_priv.can_debug_cmd && debug_support) sysfs_remove_file(&tlmi_priv.attribute_kset->kobj, &debug_cmd.attr); + kset_unregister(tlmi_priv.attribute_kset); + if (tlmi_priv.certificate_support) { + kfree(tlmi_priv.pwd_admin->certificate); + kfree(tlmi_priv.pwd_admin->signature); + kfree(tlmi_priv.pwd_admin->save_signature); + } + /* Authentication structures */ sysfs_remove_group(&tlmi_priv.pwd_admin->kobj, &auth_attr_group); kobject_put(&tlmi_priv.pwd_admin->kobj); @@ -975,6 +1316,7 @@ static int tlmi_sysfs_init(void) if (ret) goto fail_create_attr; } + /* Create authentication entries */ tlmi_priv.authentication_kset = kset_create_and_add("authentication", NULL, &tlmi_priv.class_dev->kobj); @@ -1087,6 +1429,11 @@ static int tlmi_analyze(void) if (wmi_has_guid(LENOVO_OPCODE_IF_GUID)) tlmi_priv.opcode_support = true; + if (wmi_has_guid(LENOVO_SET_BIOS_CERT_GUID) && + wmi_has_guid(LENOVO_SET_BIOS_SETTING_CERT_GUID) && + wmi_has_guid(LENOVO_SAVE_BIOS_SETTING_CERT_GUID)) + tlmi_priv.certificate_support = true; + /* * Try to find the number of valid settings of this machine * and use it to create sysfs attributes. @@ -1198,6 +1545,11 @@ static int tlmi_analyze(void) } } } + + if (tlmi_priv.certificate_support && + (tlmi_priv.pwdcfg.core.password_state & TLMI_CERT)) + tlmi_priv.pwd_admin->cert_installed = true; + return 0; fail_clear_attr: diff --git a/drivers/platform/x86/think-lmi.h b/drivers/platform/x86/think-lmi.h index e46c7f383353..4f69df6eed07 100644 --- a/drivers/platform/x86/think-lmi.h +++ b/drivers/platform/x86/think-lmi.h @@ -62,6 +62,10 @@ struct tlmi_pwd_setting { char kbdlang[TLMI_LANG_MAXLEN]; int index; /*Used for HDD and NVME auth */ enum level_option level; + bool cert_installed; + char *certificate; + char *signature; + char *save_signature; }; /* Attribute setting details */ @@ -82,6 +86,7 @@ struct think_lmi { bool pending_changes; bool can_debug_cmd; bool opcode_support; + bool certificate_support; struct tlmi_attr_setting *setting[TLMI_SETTINGS_COUNT]; struct device *class_dev;
Implementation of certificate authentication feature for Lenovo platforms. This allows for signed updates of BIOS settings. Functionality supported: - Cert support available check. At initialisation check if BIOS supports certification authentication and if a certificate is installed. Enable the sysfs nodes appropriately - certificate and signature authentication attributes to enable a user to install, update and delete a certificate using signed signatures - certificate_thumbprint to confirm installed certificate details - support to go from certificate to password based authentication - signature and save_signature attributes needed for setting BIOS attributes using certificate authentication. Tested on X1 Carbon 10 with special trial BIOS. This feature is not generally available yet but will be released later this year. Note, I also cleaned up the formating of the GUIDs when I was adding the new defines. Hope that's OK to combine in this commit. Signed-off-by: Mark Pearson <markpearson@lenovo.com> --- Changes in v2: - Combined set_signature with signature and moved save_signature under the authorisation folder - utility function to strip CR from string - Clean up code as recommended from review drivers/platform/x86/think-lmi.c | 560 +++++++++++++++++++++++++------ drivers/platform/x86/think-lmi.h | 5 + 2 files changed, 461 insertions(+), 104 deletions(-)