efi_loader: variable: support variable authentication
[oweals/u-boot.git] / lib / efi_loader / efi_variable.c
index e0d7f5736db20cfe3d1d94c4c069d93f2edd6d98..adb78470f2d64a1f1924e57d1316c65a1a740701 100644 (file)
@@ -1,17 +1,23 @@
 // SPDX-License-Identifier: GPL-2.0+
 /*
- *  EFI utils
+ * UEFI runtime variable services
  *
- *  Copyright (c) 2017 Rob Clark
+ * Copyright (c) 2017 Rob Clark
  */
 
-#include <malloc.h>
-#include <charset.h>
+#include <common.h>
 #include <efi_loader.h>
+#include <env_internal.h>
 #include <hexdump.h>
-#include <environment.h>
+#include <malloc.h>
+#include <rtc.h>
 #include <search.h>
-#include <uuid.h>
+#include <linux/compat.h>
+#include <u-boot/crc.h>
+#include "../lib/crypto/pkcs7_parser.h"
+
+const efi_guid_t efi_guid_cert_type_pkcs7 = EFI_CERT_TYPE_PKCS7_GUID;
+static bool efi_secure_boot;
 
 #define READ_ONLY BIT(31)
 
@@ -106,9 +112,10 @@ static const char *prefix(const char *str, const char *prefix)
  *
  * @str:       value of U-Boot variable
  * @attrp:     pointer to UEFI attributes
+ * @timep:     pointer to time attribute
  * Return:     pointer to remainder of U-Boot variable value
  */
-static const char *parse_attr(const char *str, u32 *attrp)
+static const char *parse_attr(const char *str, u32 *attrp, u64 *timep)
 {
        u32 attr = 0;
        char sep = '{';
@@ -125,10 +132,18 @@ static const char *parse_attr(const char *str, u32 *attrp)
 
                if ((s = prefix(str, "ro"))) {
                        attr |= READ_ONLY;
+               } else if ((s = prefix(str, "nv"))) {
+                       attr |= EFI_VARIABLE_NON_VOLATILE;
                } else if ((s = prefix(str, "boot"))) {
                        attr |= EFI_VARIABLE_BOOTSERVICE_ACCESS;
                } else if ((s = prefix(str, "run"))) {
                        attr |= EFI_VARIABLE_RUNTIME_ACCESS;
+               } else if ((s = prefix(str, "time="))) {
+                       attr |= EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS;
+                       hex2bin((u8 *)timep, s, sizeof(*timep));
+                       s += sizeof(*timep) * 2;
+               } else if (*str == '}') {
+                       break;
                } else {
                        printf("invalid attribute: %s\n", str);
                        break;
@@ -146,48 +161,291 @@ static const char *parse_attr(const char *str, u32 *attrp)
 }
 
 /**
- * efi_efi_get_variable() - retrieve value of a UEFI variable
+ * efi_secure_boot_enabled - return if secure boot is enabled or not
  *
- * This function implements the GetVariable runtime service.
+ * Return:     true if enabled, false if disabled
+ */
+bool efi_secure_boot_enabled(void)
+{
+       return efi_secure_boot;
+}
+
+#ifdef CONFIG_EFI_SECURE_BOOT
+static u8 pkcs7_hdr[] = {
+       /* SEQUENCE */
+       0x30, 0x82, 0x05, 0xc7,
+       /* OID: pkcs7-signedData */
+       0x06, 0x09, 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x07, 0x02,
+       /* Context Structured? */
+       0xa0, 0x82, 0x05, 0xb8,
+};
+
+/**
+ * efi_variable_parse_signature - parse a signature in variable
+ * @buf:       Pointer to variable's value
+ * @buflen:    Length of @buf
  *
- * See the Unified Extensible Firmware Interface (UEFI) specification for
- * details.
+ * Parse a signature embedded in variable's value and instantiate
+ * a pkcs7_message structure. Since pkcs7_parse_message() accepts only
+ * pkcs7's signedData, some header needed be prepended for correctly
+ * parsing authentication data, particularly for variable's.
  *
- * @variable_name:     name of the variable
- * @vendor:            vendor GUID
- * @attributes:                attributes of the variable
- * @data_size:         size of the buffer to which the variable value is copied
- * @data:              buffer to which the variable value is copied
- * Return:             status code
+ * Return:     Pointer to pkcs7_message structure on success, NULL on error
  */
-efi_status_t EFIAPI efi_get_variable(u16 *variable_name,
-                                    const efi_guid_t *vendor, u32 *attributes,
-                                    efi_uintn_t *data_size, void *data)
+static struct pkcs7_message *efi_variable_parse_signature(const void *buf,
+                                                         size_t buflen)
+{
+       u8 *ebuf;
+       size_t ebuflen, len;
+       struct pkcs7_message *msg;
+
+       /*
+        * This is the best assumption to check if the binary is
+        * already in a form of pkcs7's signedData.
+        */
+       if (buflen > sizeof(pkcs7_hdr) &&
+           !memcmp(&((u8 *)buf)[4], &pkcs7_hdr[4], 11)) {
+               msg = pkcs7_parse_message(buf, buflen);
+               goto out;
+       }
+
+       /*
+        * Otherwise, we should add a dummy prefix sequence for pkcs7
+        * message parser to be able to process.
+        * NOTE: EDK2 also uses similar hack in WrapPkcs7Data()
+        * in CryptoPkg/Library/BaseCryptLib/Pk/CryptPkcs7VerifyCommon.c
+        * TODO:
+        * The header should be composed in a more refined manner.
+        */
+       debug("Makeshift prefix added to authentication data\n");
+       ebuflen = sizeof(pkcs7_hdr) + buflen;
+       if (ebuflen <= 0x7f) {
+               debug("Data is too short\n");
+               return NULL;
+       }
+
+       ebuf = malloc(ebuflen);
+       if (!ebuf) {
+               debug("Out of memory\n");
+               return NULL;
+       }
+
+       memcpy(ebuf, pkcs7_hdr, sizeof(pkcs7_hdr));
+       memcpy(ebuf + sizeof(pkcs7_hdr), buf, buflen);
+       len = ebuflen - 4;
+       ebuf[2] = (len >> 8) & 0xff;
+       ebuf[3] = len & 0xff;
+       len = ebuflen - 0x13;
+       ebuf[0x11] = (len >> 8) & 0xff;
+       ebuf[0x12] = len & 0xff;
+
+       msg = pkcs7_parse_message(ebuf, ebuflen);
+
+       free(ebuf);
+
+out:
+       if (IS_ERR(msg))
+               return NULL;
+
+       return msg;
+}
+
+/**
+ * efi_variable_authenticate - authenticate a variable
+ * @variable:  Variable name in u16
+ * @vendor:    Guid of variable
+ * @data_size: Size of @data
+ * @data:      Pointer to variable's value
+ * @given_attr:        Attributes to be given at SetVariable()
+ * @env_attr:  Attributes that an existing variable holds
+ * @time:      signed time that an existing variable holds
+ *
+ * Called by efi_set_variable() to verify that the input is correct.
+ * Will replace the given data pointer with another that points to
+ * the actual data to store in the internal memory.
+ * On success, @data and @data_size will be replaced with variable's
+ * actual data, excluding authentication data, and its size, and variable's
+ * attributes and signed time will also be returned in @env_attr and @time,
+ * respectively.
+ *
+ * Return:     EFI_SUCCESS on success, status code (negative) on error
+ */
+static efi_status_t efi_variable_authenticate(u16 *variable,
+                                             const efi_guid_t *vendor,
+                                             efi_uintn_t *data_size,
+                                             const void **data, u32 given_attr,
+                                             u32 *env_attr, u64 *time)
+{
+       const struct efi_variable_authentication_2 *auth;
+       struct efi_signature_store *truststore, *truststore2;
+       struct pkcs7_message *var_sig;
+       struct efi_image_regions *regs;
+       struct efi_time timestamp;
+       struct rtc_time tm;
+       u64 new_time;
+       efi_status_t ret;
+
+       var_sig = NULL;
+       truststore = NULL;
+       truststore2 = NULL;
+       regs = NULL;
+       ret = EFI_SECURITY_VIOLATION;
+
+       if (*data_size < sizeof(struct efi_variable_authentication_2))
+               goto err;
+
+       /* authentication data */
+       auth = *data;
+       if (*data_size < (sizeof(auth->time_stamp)
+                               + auth->auth_info.hdr.dwLength))
+               goto err;
+
+       if (guidcmp(&auth->auth_info.cert_type, &efi_guid_cert_type_pkcs7))
+               goto err;
+
+       *data += sizeof(auth->time_stamp) + auth->auth_info.hdr.dwLength;
+       *data_size -= (sizeof(auth->time_stamp)
+                               + auth->auth_info.hdr.dwLength);
+
+       memcpy(&timestamp, &auth->time_stamp, sizeof(timestamp));
+       memset(&tm, 0, sizeof(tm));
+       tm.tm_year = timestamp.year;
+       tm.tm_mon = timestamp.month;
+       tm.tm_mday = timestamp.day;
+       tm.tm_hour = timestamp.hour;
+       tm.tm_min = timestamp.minute;
+       tm.tm_sec = timestamp.second;
+       new_time = rtc_mktime(&tm);
+
+       if (!efi_secure_boot_enabled()) {
+               /* finished checking */
+               *time = new_time;
+               return EFI_SUCCESS;
+       }
+
+       if (new_time <= *time)
+               goto err;
+
+       /* data to be digested */
+       regs = calloc(sizeof(*regs) + sizeof(struct image_region) * 5, 1);
+       if (!regs)
+               goto err;
+       regs->max = 5;
+       efi_image_region_add(regs, (uint8_t *)variable,
+                            (uint8_t *)variable
+                               + u16_strlen(variable) * sizeof(u16), 1);
+       efi_image_region_add(regs, (uint8_t *)vendor,
+                            (uint8_t *)vendor + sizeof(*vendor), 1);
+       efi_image_region_add(regs, (uint8_t *)&given_attr,
+                            (uint8_t *)&given_attr + sizeof(given_attr), 1);
+       efi_image_region_add(regs, (uint8_t *)&timestamp,
+                            (uint8_t *)&timestamp + sizeof(timestamp), 1);
+       efi_image_region_add(regs, (uint8_t *)*data,
+                            (uint8_t *)*data + *data_size, 1);
+
+       /* variable's signature list */
+       if (auth->auth_info.hdr.dwLength < sizeof(auth->auth_info))
+               goto err;
+       var_sig = efi_variable_parse_signature(auth->auth_info.cert_data,
+                                              auth->auth_info.hdr.dwLength
+                                                  - sizeof(auth->auth_info));
+       if (IS_ERR(var_sig)) {
+               debug("Parsing variable's signature failed\n");
+               var_sig = NULL;
+               goto err;
+       }
+
+       /* signature database used for authentication */
+       if (u16_strcmp(variable, L"PK") == 0 ||
+           u16_strcmp(variable, L"KEK") == 0) {
+               /* with PK */
+               truststore = efi_sigstore_parse_sigdb(L"PK");
+               if (!truststore)
+                       goto err;
+       } else if (u16_strcmp(variable, L"db") == 0 ||
+                  u16_strcmp(variable, L"dbx") == 0) {
+               /* with PK and KEK */
+               truststore = efi_sigstore_parse_sigdb(L"KEK");
+               truststore2 = efi_sigstore_parse_sigdb(L"PK");
+
+               if (!truststore) {
+                       if (!truststore2)
+                               goto err;
+
+                       truststore = truststore2;
+                       truststore2 = NULL;
+               }
+       } else {
+               /* TODO: support private authenticated variables */
+               goto err;
+       }
+
+       /* verify signature */
+       if (efi_signature_verify_with_sigdb(regs, var_sig, truststore, NULL)) {
+               debug("Verified\n");
+       } else {
+               if (truststore2 &&
+                   efi_signature_verify_with_sigdb(regs, var_sig,
+                                                   truststore2, NULL)) {
+                       debug("Verified\n");
+               } else {
+                       debug("Verifying variable's signature failed\n");
+                       goto err;
+               }
+       }
+
+       /* finished checking */
+       *time = rtc_mktime(&tm);
+       ret = EFI_SUCCESS;
+
+err:
+       efi_sigstore_free(truststore);
+       efi_sigstore_free(truststore2);
+       pkcs7_free_message(var_sig);
+       free(regs);
+
+       return ret;
+}
+#else
+static efi_status_t efi_variable_authenticate(u16 *variable,
+                                             const efi_guid_t *vendor,
+                                             efi_uintn_t *data_size,
+                                             const void **data, u32 given_attr,
+                                             u32 *env_attr, u64 *time)
+{
+       return EFI_SUCCESS;
+}
+#endif /* CONFIG_EFI_SECURE_BOOT */
+
+static
+efi_status_t EFIAPI efi_get_variable_common(u16 *variable_name,
+                                           const efi_guid_t *vendor,
+                                           u32 *attributes,
+                                           efi_uintn_t *data_size, void *data,
+                                           bool is_non_volatile)
 {
        char *native_name;
        efi_status_t ret;
        unsigned long in_size;
-       const char *val, *s;
+       const char *val = NULL, *s;
+       u64 time = 0;
        u32 attr;
 
-       EFI_ENTRY("\"%ls\" %pUl %p %p %p", variable_name, vendor, attributes,
-                 data_size, data);
-
        if (!variable_name || !vendor || !data_size)
                return EFI_EXIT(EFI_INVALID_PARAMETER);
 
        ret = efi_to_native(&native_name, variable_name, vendor);
        if (ret)
-               return EFI_EXIT(ret);
+               return ret;
 
-       debug("%s: get '%s'\n", __func__, native_name);
+       EFI_PRINT("get '%s'\n", native_name);
 
        val = env_get(native_name);
        free(native_name);
        if (!val)
-               return EFI_EXIT(EFI_NOT_FOUND);
+               return EFI_NOT_FOUND;
 
-       val = parse_attr(val, &attr);
+       val = parse_attr(val, &attr, &time);
 
        in_size = *data_size;
 
@@ -196,46 +454,109 @@ efi_status_t EFIAPI efi_get_variable(u16 *variable_name,
 
                /* number of hexadecimal digits must be even */
                if (len & 1)
-                       return EFI_EXIT(EFI_DEVICE_ERROR);
+                       return EFI_DEVICE_ERROR;
 
                /* two characters per byte: */
                len /= 2;
                *data_size = len;
 
-               if (in_size < len)
-                       return EFI_EXIT(EFI_BUFFER_TOO_SMALL);
+               if (in_size < len) {
+                       ret = EFI_BUFFER_TOO_SMALL;
+                       goto out;
+               }
 
-               if (!data)
-                       return EFI_EXIT(EFI_INVALID_PARAMETER);
+               if (!data) {
+                       debug("Variable with no data shouldn't exist.\n");
+                       return EFI_INVALID_PARAMETER;
+               }
 
                if (hex2bin(data, s, len))
-                       return EFI_EXIT(EFI_DEVICE_ERROR);
+                       return EFI_DEVICE_ERROR;
 
-               debug("%s: got value: \"%s\"\n", __func__, s);
+               EFI_PRINT("got value: \"%s\"\n", s);
        } else if ((s = prefix(val, "(utf8)"))) {
                unsigned len = strlen(s) + 1;
 
                *data_size = len;
 
-               if (in_size < len)
-                       return EFI_EXIT(EFI_BUFFER_TOO_SMALL);
+               if (in_size < len) {
+                       ret = EFI_BUFFER_TOO_SMALL;
+                       goto out;
+               }
 
-               if (!data)
-                       return EFI_EXIT(EFI_INVALID_PARAMETER);
+               if (!data) {
+                       debug("Variable with no data shouldn't exist.\n");
+                       return EFI_INVALID_PARAMETER;
+               }
 
                memcpy(data, s, len);
                ((char *)data)[len] = '\0';
 
-               debug("%s: got value: \"%s\"\n", __func__, (char *)data);
+               EFI_PRINT("got value: \"%s\"\n", (char *)data);
        } else {
-               debug("%s: invalid value: '%s'\n", __func__, val);
-               return EFI_EXIT(EFI_DEVICE_ERROR);
+               EFI_PRINT("invalid value: '%s'\n", val);
+               return EFI_DEVICE_ERROR;
        }
 
+out:
        if (attributes)
                *attributes = attr & EFI_VARIABLE_MASK;
 
-       return EFI_EXIT(EFI_SUCCESS);
+       return ret;
+}
+
+static
+efi_status_t EFIAPI efi_get_volatile_variable(u16 *variable_name,
+                                             const efi_guid_t *vendor,
+                                             u32 *attributes,
+                                             efi_uintn_t *data_size,
+                                             void *data)
+{
+       return efi_get_variable_common(variable_name, vendor, attributes,
+                                      data_size, data, false);
+}
+
+efi_status_t EFIAPI efi_get_nonvolatile_variable(u16 *variable_name,
+                                                const efi_guid_t *vendor,
+                                                u32 *attributes,
+                                                efi_uintn_t *data_size,
+                                                void *data)
+{
+       return efi_get_variable_common(variable_name, vendor, attributes,
+                                      data_size, data, true);
+}
+
+/**
+ * efi_efi_get_variable() - retrieve value of a UEFI variable
+ *
+ * This function implements the GetVariable runtime service.
+ *
+ * See the Unified Extensible Firmware Interface (UEFI) specification for
+ * details.
+ *
+ * @variable_name:     name of the variable
+ * @vendor:            vendor GUID
+ * @attributes:                attributes of the variable
+ * @data_size:         size of the buffer to which the variable value is copied
+ * @data:              buffer to which the variable value is copied
+ * Return:             status code
+ */
+efi_status_t EFIAPI efi_get_variable(u16 *variable_name,
+                                    const efi_guid_t *vendor, u32 *attributes,
+                                    efi_uintn_t *data_size, void *data)
+{
+       efi_status_t ret;
+
+       EFI_ENTRY("\"%ls\" %pUl %p %p %p", variable_name, vendor, attributes,
+                 data_size, data);
+
+       ret = efi_get_volatile_variable(variable_name, vendor, attributes,
+                                       data_size, data);
+       if (ret == EFI_NOT_FOUND)
+               ret = efi_get_nonvolatile_variable(variable_name, vendor,
+                                                  attributes, data_size, data);
+
+       return EFI_EXIT(ret);
 }
 
 static char *efi_variables_list;
@@ -256,8 +577,8 @@ static char *efi_cur_variable;
  * is the size of variable name including NULL.
  *
  * Return:             EFI_SUCCESS if parsing is OK, EFI_NOT_FOUND when
                      the entire variable list has been returned,
                      otherwise non-zero status code
*                     the entire variable list has been returned,
*                     otherwise non-zero status code
  */
 static efi_status_t parse_uboot_variable(char *variable,
                                         efi_uintn_t *variable_name_size,
@@ -266,7 +587,9 @@ static efi_status_t parse_uboot_variable(char *variable,
                                         u32 *attributes)
 {
        char *guid, *name, *end, c;
-       unsigned long name_len;
+       size_t name_len;
+       efi_uintn_t old_variable_name_size;
+       u64 time;
        u16 *p;
 
        guid = strchr(variable, '_');
@@ -282,17 +605,17 @@ static efi_status_t parse_uboot_variable(char *variable,
                return EFI_INVALID_PARAMETER;
 
        name_len = end - name;
-       if (*variable_name_size < (name_len + 1)) {
-               *variable_name_size = name_len + 1;
+       old_variable_name_size = *variable_name_size;
+       *variable_name_size = sizeof(u16) * (name_len + 1);
+       if (old_variable_name_size < *variable_name_size)
                return EFI_BUFFER_TOO_SMALL;
-       }
+
        end++; /* point to value */
 
        /* variable name */
        p = variable_name;
        utf8_utf16_strncpy(&p, name, name_len);
        variable_name[name_len] = 0;
-       *variable_name_size = name_len + 1;
 
        /* guid */
        c = *(name - 1);
@@ -301,13 +624,14 @@ static efi_status_t parse_uboot_variable(char *variable,
        *(name - 1) = c;
 
        /* attributes */
-       parse_attr(end, attributes);
+       parse_attr(end, attributes, &time);
 
        return EFI_SUCCESS;
 }
 
 /**
  * efi_get_next_variable_name() - enumerate the current variable names
+ *
  * @variable_name_size:        size of variable_name buffer in byte
  * @variable_name:     name of uefi variable's name in u16
  * @vendor:            vendor's guid
@@ -315,14 +639,13 @@ static efi_status_t parse_uboot_variable(char *variable,
  * This function implements the GetNextVariableName service.
  *
  * See the Unified Extensible Firmware Interface (UEFI) specification for
- * details: http://wiki.phoenix.com/wiki/index.php/
- *             EFI_RUNTIME_SERVICES#GetNextVariableName.28.29
+ * details.
  *
  * Return: status code
  */
 efi_status_t EFIAPI efi_get_next_variable_name(efi_uintn_t *variable_name_size,
                                               u16 *variable_name,
-                                              const efi_guid_t *vendor)
+                                              efi_guid_t *vendor)
 {
        char *native_name, *variable;
        ssize_t name_len, list_len;
@@ -335,7 +658,7 @@ efi_status_t EFIAPI efi_get_next_variable_name(efi_uintn_t *variable_name_size,
        EFI_ENTRY("%p \"%ls\" %pUl", variable_name_size, variable_name, vendor);
 
        if (!variable_name_size || !variable_name || !vendor)
-               EFI_EXIT(EFI_INVALID_PARAMETER);
+               return EFI_EXIT(EFI_INVALID_PARAMETER);
 
        if (variable_name[0]) {
                /* check null-terminated string */
@@ -383,7 +706,7 @@ efi_status_t EFIAPI efi_get_next_variable_name(efi_uintn_t *variable_name_size,
                list_len = hexport_r(&env_htab, '\n',
                                     H_MATCH_REGEX | H_MATCH_KEY,
                                     &efi_variables_list, 0, 1, regexlist);
-               /* 1 indicates that no match was found */
+
                if (list_len <= 1)
                        return EFI_EXIT(EFI_NOT_FOUND);
 
@@ -396,103 +719,384 @@ efi_status_t EFIAPI efi_get_next_variable_name(efi_uintn_t *variable_name_size,
        return EFI_EXIT(ret);
 }
 
-/**
- * efi_efi_set_variable() - set value of a UEFI variable
- *
- * This function implements the SetVariable runtime service.
- *
- * See the Unified Extensible Firmware Interface (UEFI) specification for
- * details.
- *
- * @variable_name:     name of the variable
- * @vendor:            vendor GUID
- * @attributes:                attributes of the variable
- * @data_size:         size of the buffer with the variable value
- * @data:              buffer with the variable value
- * Return:             status code
- */
-efi_status_t EFIAPI efi_set_variable(u16 *variable_name,
-                                    const efi_guid_t *vendor, u32 attributes,
-                                    efi_uintn_t data_size, const void *data)
+static
+efi_status_t EFIAPI efi_set_variable_common(u16 *variable_name,
+                                           const efi_guid_t *vendor,
+                                           u32 attributes,
+                                           efi_uintn_t data_size,
+                                           const void *data,
+                                           bool ro_check,
+                                           bool is_non_volatile)
 {
-       char *native_name = NULL, *val = NULL, *s;
-       efi_status_t ret = EFI_SUCCESS;
+       char *native_name = NULL, *old_data = NULL, *val = NULL, *s;
+       efi_uintn_t old_size;
+       bool append, delete;
+       u64 time = 0;
        u32 attr;
+       efi_status_t ret = EFI_SUCCESS;
 
-       EFI_ENTRY("\"%ls\" %pUl %x %zu %p", variable_name, vendor, attributes,
-                 data_size, data);
+       debug("%s: set '%s'\n", __func__, native_name);
 
-       if (!variable_name || !vendor) {
+       if (!variable_name || !*variable_name || !vendor ||
+           ((attributes & EFI_VARIABLE_RUNTIME_ACCESS) &&
+            !(attributes & EFI_VARIABLE_BOOTSERVICE_ACCESS))) {
                ret = EFI_INVALID_PARAMETER;
-               goto out;
+               goto err;
        }
 
        ret = efi_to_native(&native_name, variable_name, vendor);
        if (ret)
-               goto out;
+               goto err;
+
+       /* check if a variable exists */
+       old_size = 0;
+       attr = 0;
+       ret = EFI_CALL(efi_get_variable(variable_name, vendor, &attr,
+                                       &old_size, NULL));
+       if (ret == EFI_BUFFER_TOO_SMALL) {
+               if ((is_non_volatile && !(attr & EFI_VARIABLE_NON_VOLATILE)) ||
+                   (!is_non_volatile && (attr & EFI_VARIABLE_NON_VOLATILE))) {
+                       ret = EFI_INVALID_PARAMETER;
+                       goto err;
+               }
+       }
+
+       append = !!(attributes & EFI_VARIABLE_APPEND_WRITE);
+       attributes &= ~(u32)EFI_VARIABLE_APPEND_WRITE;
+       delete = !append && (!data_size || !attributes);
+
+       /* check attributes */
+       if (old_size) {
+               if (ro_check && (attr & READ_ONLY)) {
+                       ret = EFI_WRITE_PROTECTED;
+                       goto err;
+               }
+
+               /* attributes won't be changed */
+               if (!delete &&
+                   ((ro_check && attr != attributes) ||
+                    (!ro_check && ((attr & ~(u32)READ_ONLY)
+                                   != (attributes & ~(u32)READ_ONLY))))) {
+                       ret = EFI_INVALID_PARAMETER;
+                       goto err;
+               }
+       } else {
+               if (delete || append) {
+                       /*
+                        * Trying to delete or to update a non-existent
+                        * variable.
+                        */
+                       ret = EFI_NOT_FOUND;
+                       goto err;
+               }
+       }
 
-#define ACCESS_ATTR (EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_BOOTSERVICE_ACCESS)
+       if (((!u16_strcmp(variable_name, L"PK") ||
+             !u16_strcmp(variable_name, L"KEK")) &&
+               !guidcmp(vendor, &efi_global_variable_guid)) ||
+           ((!u16_strcmp(variable_name, L"db") ||
+             !u16_strcmp(variable_name, L"dbx")) &&
+               !guidcmp(vendor, &efi_guid_image_security_database))) {
+               /* authentication is mandatory */
+               if (!(attributes &
+                     EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS)) {
+                       debug("%ls: AUTHENTICATED_WRITE_ACCESS required\n",
+                             variable_name);
+                       ret = EFI_INVALID_PARAMETER;
+                       goto err;
+               }
+       }
 
-       if ((data_size == 0) || !(attributes & ACCESS_ATTR)) {
-               /* delete the variable: */
-               env_set(native_name, NULL);
+       /* authenticate a variable */
+       if (IS_ENABLED(CONFIG_EFI_SECURE_BOOT)) {
+               if (attributes & EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS) {
+                       ret = EFI_INVALID_PARAMETER;
+                       goto err;
+               }
+               if (attributes &
+                   EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS) {
+                       ret = efi_variable_authenticate(variable_name, vendor,
+                                                       &data_size, &data,
+                                                       attributes, &attr,
+                                                       &time);
+                       if (ret != EFI_SUCCESS)
+                               goto err;
+
+                       /* last chance to check for delete */
+                       if (!data_size)
+                               delete = true;
+               }
+       } else {
+               if (attributes &
+                   (EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS |
+                    EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS)) {
+                       debug("Secure boot is not configured\n");
+                       ret = EFI_INVALID_PARAMETER;
+                       goto err;
+               }
+       }
+
+       /* delete a variable */
+       if (delete) {
+               /* !old_size case has been handled before */
+               val = NULL;
                ret = EFI_SUCCESS;
                goto out;
        }
 
-       val = env_get(native_name);
-       if (val) {
-               parse_attr(val, &attr);
-
-               if (attr & READ_ONLY) {
-                       /* We should not free val */
-                       val = NULL;
-                       ret = EFI_WRITE_PROTECTED;
-                       goto out;
+       if (append) {
+               old_data = malloc(old_size);
+               if (!old_data) {
+                       return EFI_OUT_OF_RESOURCES;
+                       goto err;
                }
+               ret = EFI_CALL(efi_get_variable(variable_name, vendor,
+                                               &attr, &old_size, old_data));
+               if (ret != EFI_SUCCESS)
+                       goto err;
+       } else {
+               old_size = 0;
        }
 
-       val = malloc(2 * data_size + strlen("{ro,run,boot}(blob)") + 1);
+       val = malloc(2 * old_size + 2 * data_size
+                    + strlen("{ro,run,boot,nv,time=0123456701234567}(blob)")
+                    + 1);
        if (!val) {
                ret = EFI_OUT_OF_RESOURCES;
-               goto out;
+               goto err;
        }
 
        s = val;
 
        /*
         * store attributes
-        * TODO: several attributes are not supported
         */
-       attributes &= (EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS);
+       attributes &= (READ_ONLY |
+                      EFI_VARIABLE_NON_VOLATILE |
+                      EFI_VARIABLE_BOOTSERVICE_ACCESS |
+                      EFI_VARIABLE_RUNTIME_ACCESS |
+                      EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS);
        s += sprintf(s, "{");
        while (attributes) {
-               u32 attr = 1 << (ffs(attributes) - 1);
+               attr = 1 << (ffs(attributes) - 1);
 
-               if (attr == EFI_VARIABLE_BOOTSERVICE_ACCESS)
+               if (attr == READ_ONLY) {
+                       s += sprintf(s, "ro");
+               } else if (attr == EFI_VARIABLE_NON_VOLATILE) {
+                       s += sprintf(s, "nv");
+               } else if (attr == EFI_VARIABLE_BOOTSERVICE_ACCESS) {
                        s += sprintf(s, "boot");
-               else if (attr == EFI_VARIABLE_RUNTIME_ACCESS)
+               } else if (attr == EFI_VARIABLE_RUNTIME_ACCESS) {
                        s += sprintf(s, "run");
+               } else if (attr ==
+                          EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS) {
+                       s += sprintf(s, "time=");
+                       s = bin2hex(s, (u8 *)&time, sizeof(time));
+               }
 
                attributes &= ~attr;
                if (attributes)
                        s += sprintf(s, ",");
        }
        s += sprintf(s, "}");
+       s += sprintf(s, "(blob)");
 
        /* store payload: */
-       s += sprintf(s, "(blob)");
+       if (append)
+               s = bin2hex(s, old_data, old_size);
        s = bin2hex(s, data, data_size);
        *s = '\0';
 
-       debug("%s: setting: %s=%s\n", __func__, native_name, val);
+       EFI_PRINT("setting: %s=%s\n", native_name, val);
 
+out:
        if (env_set(native_name, val))
                ret = EFI_DEVICE_ERROR;
+       else
+               ret = EFI_SUCCESS;
 
-out:
+err:
        free(native_name);
+       free(old_data);
        free(val);
 
-       return EFI_EXIT(ret);
+       return ret;
+}
+
+static
+efi_status_t EFIAPI efi_set_volatile_variable(u16 *variable_name,
+                                             const efi_guid_t *vendor,
+                                             u32 attributes,
+                                             efi_uintn_t data_size,
+                                             const void *data,
+                                             bool ro_check)
+{
+       return efi_set_variable_common(variable_name, vendor, attributes,
+                                      data_size, data, ro_check, false);
+}
+
+efi_status_t EFIAPI efi_set_nonvolatile_variable(u16 *variable_name,
+                                                const efi_guid_t *vendor,
+                                                u32 attributes,
+                                                efi_uintn_t data_size,
+                                                const void *data,
+                                                bool ro_check)
+{
+       efi_status_t ret;
+
+       ret = efi_set_variable_common(variable_name, vendor, attributes,
+                                     data_size, data, ro_check, true);
+
+       return ret;
+}
+
+static efi_status_t efi_set_variable_internal(u16 *variable_name,
+                                             const efi_guid_t *vendor,
+                                             u32 attributes,
+                                             efi_uintn_t data_size,
+                                             const void *data,
+                                             bool ro_check)
+{
+       efi_status_t ret;
+
+       if (attributes & EFI_VARIABLE_NON_VOLATILE)
+               ret = efi_set_nonvolatile_variable(variable_name, vendor,
+                                                  attributes,
+                                                  data_size, data, ro_check);
+       else
+               ret = efi_set_volatile_variable(variable_name, vendor,
+                                               attributes, data_size, data,
+                                               ro_check);
+
+       return ret;
+}
+
+/**
+ * efi_set_variable() - set value of a UEFI variable
+ *
+ * This function implements the SetVariable runtime service.
+ *
+ * See the Unified Extensible Firmware Interface (UEFI) specification for
+ * details.
+ *
+ * @variable_name:     name of the variable
+ * @vendor:            vendor GUID
+ * @attributes:                attributes of the variable
+ * @data_size:         size of the buffer with the variable value
+ * @data:              buffer with the variable value
+ * Return:             status code
+ */
+efi_status_t EFIAPI efi_set_variable(u16 *variable_name,
+                                    const efi_guid_t *vendor, u32 attributes,
+                                    efi_uintn_t data_size, const void *data)
+{
+       EFI_ENTRY("\"%ls\" %pUl %x %zu %p", variable_name, vendor, attributes,
+                 data_size, data);
+
+       /* READ_ONLY bit is not part of API */
+       attributes &= ~(u32)READ_ONLY;
+
+       return EFI_EXIT(efi_set_variable_internal(variable_name, vendor,
+                                                 attributes, data_size, data,
+                                                 true));
+}
+
+/**
+ * efi_query_variable_info() - get information about EFI variables
+ *
+ * This function implements the QueryVariableInfo() runtime service.
+ *
+ * See the Unified Extensible Firmware Interface (UEFI) specification for
+ * details.
+ *
+ * @attributes:                                bitmask to select variables to be
+ *                                     queried
+ * @maximum_variable_storage_size:     maximum size of storage area for the
+ *                                     selected variable types
+ * @remaining_variable_storage_size:   remaining size of storage are for the
+ *                                     selected variable types
+ * @maximum_variable_size:             maximum size of a variable of the
+ *                                     selected type
+ * Returns:                            status code
+ */
+efi_status_t __efi_runtime EFIAPI efi_query_variable_info(
+                       u32 attributes,
+                       u64 *maximum_variable_storage_size,
+                       u64 *remaining_variable_storage_size,
+                       u64 *maximum_variable_size)
+{
+       return EFI_UNSUPPORTED;
+}
+
+/**
+ * efi_get_variable_runtime() - runtime implementation of GetVariable()
+ *
+ * @variable_name:     name of the variable
+ * @vendor:            vendor GUID
+ * @attributes:                attributes of the variable
+ * @data_size:         size of the buffer to which the variable value is copied
+ * @data:              buffer to which the variable value is copied
+ * Return:             status code
+ */
+static efi_status_t __efi_runtime EFIAPI
+efi_get_variable_runtime(u16 *variable_name, const efi_guid_t *vendor,
+                        u32 *attributes, efi_uintn_t *data_size, void *data)
+{
+       return EFI_UNSUPPORTED;
+}
+
+/**
+ * efi_get_next_variable_name_runtime() - runtime implementation of
+ *                                       GetNextVariable()
+ *
+ * @variable_name_size:        size of variable_name buffer in byte
+ * @variable_name:     name of uefi variable's name in u16
+ * @vendor:            vendor's guid
+ * Return: status code
+ */
+static efi_status_t __efi_runtime EFIAPI
+efi_get_next_variable_name_runtime(efi_uintn_t *variable_name_size,
+                                  u16 *variable_name, efi_guid_t *vendor)
+{
+       return EFI_UNSUPPORTED;
+}
+
+/**
+ * efi_set_variable_runtime() - runtime implementation of SetVariable()
+ *
+ * @variable_name:     name of the variable
+ * @vendor:            vendor GUID
+ * @attributes:                attributes of the variable
+ * @data_size:         size of the buffer with the variable value
+ * @data:              buffer with the variable value
+ * Return:             status code
+ */
+static efi_status_t __efi_runtime EFIAPI
+efi_set_variable_runtime(u16 *variable_name, const efi_guid_t *vendor,
+                        u32 attributes, efi_uintn_t data_size,
+                        const void *data)
+{
+       return EFI_UNSUPPORTED;
+}
+
+/**
+ * efi_variables_boot_exit_notify() - notify ExitBootServices() is called
+ */
+void efi_variables_boot_exit_notify(void)
+{
+       efi_runtime_services.get_variable = efi_get_variable_runtime;
+       efi_runtime_services.get_next_variable_name =
+                               efi_get_next_variable_name_runtime;
+       efi_runtime_services.set_variable = efi_set_variable_runtime;
+       efi_update_table_header_crc32(&efi_runtime_services.hdr);
+}
+
+/**
+ * efi_init_variables() - initialize variable services
+ *
+ * Return:     status code
+ */
+efi_status_t efi_init_variables(void)
+{
+       return EFI_SUCCESS;
 }