[PATCH v4 05/16] efi_loader: variable: support variable authentication

AKASHI Takahiro takahiro.akashi at linaro.org
Fri Jan 17 06:35:59 CET 2020


On Wed, Jan 08, 2020 at 11:54:26PM +0100, Heinrich Schuchardt wrote:
> On 12/18/19 1:45 AM, AKASHI Takahiro wrote:
> >With this commit, EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS
> >is supported for authenticated variables and the system secure state
> >will transfer between setup mode and user mode as UEFI specification
> >section 32.3 describes.
> >
> >Internally, authentication data is stored as part of authenticated
> >variable's value. It is nothing but a pkcs7 message (but we need some
> >wrapper, see efi_variable_parse_signature()) and will be validated by
> >efi_variable_authenticate(), hence efi_signature_verify_with_db().
> >
> >Associated time value will be encoded in "{...,time=...}" along with
> >other UEFI variable's attributes.
> >
> >Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>
> >---
> >  include/efi_loader.h          |   3 +
> >  lib/efi_loader/efi_variable.c | 665 ++++++++++++++++++++++++++++------
> >  2 files changed, 564 insertions(+), 104 deletions(-)
> >
> >diff --git a/include/efi_loader.h b/include/efi_loader.h
> >index 3b3618e0be24..1f88caf86709 100644
> >--- a/include/efi_loader.h
> >+++ b/include/efi_loader.h
> >@@ -175,6 +175,7 @@ extern const efi_guid_t efi_guid_image_security_database;
> >  extern const efi_guid_t efi_guid_sha256;
> >  extern const efi_guid_t efi_guid_cert_x509;
> >  extern const efi_guid_t efi_guid_cert_x509_sha256;
> >+extern const efi_guid_t efi_guid_cert_type_pkcs7;
> >
> >  extern unsigned int __efi_runtime_start, __efi_runtime_stop;
> >  extern unsigned int __efi_runtime_rel_start, __efi_runtime_rel_stop;
> >@@ -723,6 +724,8 @@ efi_status_t efi_image_region_add(struct efi_image_regions *regs,
> >
> >  void efi_sigstore_free(struct efi_signature_store *sigstore);
> >  struct efi_signature_store *efi_sigstore_parse_sigdb(u16 *name);
> >+
> >+bool efi_secure_boot_enabled(void);
> >  #endif /* CONFIG_EFI_SECURE_BOOT */
> >
> >  #else /* CONFIG_IS_ENABLED(EFI_LOADER) */
> >diff --git a/lib/efi_loader/efi_variable.c b/lib/efi_loader/efi_variable.c
> >index 46f35bc60ba0..171b4abb4c58 100644
> >--- a/lib/efi_loader/efi_variable.c
> >+++ b/lib/efi_loader/efi_variable.c
> >@@ -10,7 +10,13 @@
> >  #include <env_internal.h>
> >  #include <hexdump.h>
> >  #include <malloc.h>
> >+#include <rtc.h>
> >  #include <search.h>
> >+#include <linux/compat.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)
> >
> >@@ -107,7 +113,7 @@ static const char *prefix(const char *str, const char *prefix)
> >   * @attrp:	pointer to UEFI attributes
> >   * 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 = '{';
> >@@ -130,6 +136,12 @@ static const char *parse_attr(const char *str, u32 *attrp)
> >  			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;
> >@@ -147,48 +159,291 @@ static const char *parse_attr(const char *str, u32 *attrp)
> >  }
> >
> >  /**
> >- * 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;
> >+	const 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);
> >+
> >+	timestamp = &auth->time_stamp;
> 
> This does not compile with GCC 9.2.1:
> 
> lib/efi_loader/efi_variable.c: In function ‘efi_variable_authenticate’:
> lib/efi_loader/efi_variable.c:554:14: error: taking address of packed
> member of ‘struct efi_variable_authentication_2’ may result in an
> unaligned pointer value [-Werror=address-of-packed-member]
>   554 |  timestamp = &auth->time_stamp;
>       |              ^~~~~~~~~~~~~~~~~

Okay.
The line will be replaced with memcpy.

Thanks,
-Takahiro Akashi


> Best regards
> 
> Heinrich
> 
> >+	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;
> >
> >  	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;
> >
> >@@ -197,7 +452,7 @@ 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;
> >@@ -208,11 +463,13 @@ efi_status_t EFIAPI efi_get_variable(u16 *variable_name,
> >  			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;
> >
> >  		EFI_PRINT("got value: \"%s\"\n", s);
> >  	} else if ((s = prefix(val, "(utf8)"))) {
> >@@ -225,8 +482,10 @@ efi_status_t EFIAPI efi_get_variable(u16 *variable_name,
> >  			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';
> >@@ -234,13 +493,67 @@ efi_status_t EFIAPI efi_get_variable(u16 *variable_name,
> >  		EFI_PRINT("got value: \"%s\"\n", (char *)data);
> >  	} else {
> >  		EFI_PRINT("invalid value: '%s'\n", val);
> >-		return EFI_EXIT(EFI_DEVICE_ERROR);
> >+		return EFI_DEVICE_ERROR;
> >  	}
> >
> >  out:
> >  	if (attributes)
> >  		*attributes = attr & EFI_VARIABLE_MASK;
> >
> >+	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);
> >  }
> >
> >@@ -273,6 +586,7 @@ static efi_status_t parse_uboot_variable(char *variable,
> >  {
> >  	char *guid, *name, *end, c;
> >  	unsigned long name_len;
> >+	u64 time;
> >  	u16 *p;
> >
> >  	guid = strchr(variable, '_');
> >@@ -307,7 +621,7 @@ 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;
> >  }
> >@@ -389,7 +703,7 @@ 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);
> >
> >@@ -402,143 +716,286 @@ efi_status_t EFIAPI efi_get_next_variable_name(efi_uintn_t *variable_name_size,
> >  	return EFI_EXIT(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)
> >+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;
> >-	const char *old_val;
> >-	size_t old_size;
> >-	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 || !*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;
> >+		}
> >+	}
> >
> >-	old_val = env_get(native_name);
> >-	if (old_val) {
> >-		old_val = parse_attr(old_val, &attr);
> >+	append = !!(attributes & EFI_VARIABLE_APPEND_WRITE);
> >+	attributes &= ~(u32)EFI_VARIABLE_APPEND_WRITE;
> >+	delete = !append && (!data_size || !attributes);
> >
> >-		/* check read-only first */
> >-		if (attr & READ_ONLY) {
> >+	/* check attributes */
> >+	if (old_size) {
> >+		if (ro_check && (attr & READ_ONLY)) {
> >  			ret = EFI_WRITE_PROTECTED;
> >-			goto out;
> >-		}
> >-
> >-		if ((data_size == 0 &&
> >-		     !(attributes & EFI_VARIABLE_APPEND_WRITE)) ||
> >-		    !attributes) {
> >-			/* delete the variable: */
> >-			env_set(native_name, NULL);
> >-			ret = EFI_SUCCESS;
> >-			goto out;
> >+			goto err;
> >  		}
> >
> >  		/* attributes won't be changed */
> >-		if (attr != (attributes & ~EFI_VARIABLE_APPEND_WRITE)) {
> >+		if (!delete &&
> >+		    ((ro_check && attr != attributes) ||
> >+		     (!ro_check && ((attr & ~(u32)READ_ONLY)
> >+				    != (attributes & ~(u32)READ_ONLY))))) {
> >  			ret = EFI_INVALID_PARAMETER;
> >-			goto out;
> >-		}
> >-
> >-		if (attributes & EFI_VARIABLE_APPEND_WRITE) {
> >-			if (!prefix(old_val, "(blob)")) {
> >-				ret = EFI_DEVICE_ERROR;
> >-				goto out;
> >-			}
> >-			old_size = strlen(old_val);
> >-		} else {
> >-			old_size = 0;
> >+			goto err;
> >  		}
> >  	} else {
> >-		if (data_size == 0 || !attributes ||
> >-		    (attributes & EFI_VARIABLE_APPEND_WRITE)) {
> >+		if (delete || append) {
> >  			/*
> >  			 * Trying to delete or to update a non-existent
> >  			 * variable.
> >  			 */
> >  			ret = EFI_NOT_FOUND;
> >-			goto out;
> >+			goto err;
> >+		}
> >+	}
> >+
> >+	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;
> >  		}
> >+	}
> >+
> >+	/* 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;
> >+	}
> >
> >+	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(old_size + 2 * data_size
> >-		     + strlen("{ro,run,boot,nv}(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 */
> >-	attributes &= (EFI_VARIABLE_NON_VOLATILE |
> >+	/*
> >+	 * store attributes
> >+	 */
> >+	attributes &= (READ_ONLY |
> >+		       EFI_VARIABLE_NON_VOLATILE |
> >  		       EFI_VARIABLE_BOOTSERVICE_ACCESS |
> >-		       EFI_VARIABLE_RUNTIME_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_NON_VOLATILE)
> >+		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)
> >+		} 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, "}");
> >-
> >-	if (old_size)
> >-		/* APPEND_WRITE */
> >-		s += sprintf(s, old_val);
> >-	else
> >-		s += sprintf(s, "(blob)");
> >+	s += sprintf(s, "(blob)");
> >
> >  	/* store payload: */
> >+	if (append)
> >+		s = bin2hex(s, old_data, old_size);
> >  	s = bin2hex(s, data, data_size);
> >  	*s = '\0';
> >
> >  	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));
> >  }
> >
> >  /**
> >
> 


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