1 files changed, 334 insertions, 83 deletions

diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index fed08b661711..7acafb80fd4c 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -79,6 +79,7 @@
 #include <linux/device.h>
 #include <linux/slab.h>
 #include <linux/pstore.h>
+#include <linux/ctype.h>
 
 #include <linux/fs.h>
 #include <linux/ramfs.h>
@@ -102,6 +103,11 @@ MODULE_VERSION(EFIVARS_VERSION);
  */
 #define GUID_LEN 36
 
+static bool efivars_pstore_disable =
+	IS_ENABLED(CONFIG_EFI_VARS_PSTORE_DEFAULT_DISABLE);
+
+module_param_named(pstore_disable, efivars_pstore_disable, bool, 0644);
+
 /*
  * The maximum size of VariableName + Data = 1024
  * Therefore, it's reasonable to save that much
@@ -164,6 +170,7 @@ efivar_create_sysfs_entry(struct efivars *efivars,
 
 static void efivar_update_sysfs_entries(struct work_struct *);
 static DECLARE_WORK(efivar_work, efivar_update_sysfs_entries);
+static bool efivar_wq_enabled = true;
 
 /* Return the number of unicode characters in data */
 static unsigned long
@@ -425,6 +432,44 @@ get_var_data(struct efivars *efivars, struct efi_variable *var)
 	return status;
 }
 
+static efi_status_t
+check_var_size_locked(struct efivars *efivars, u32 attributes,
+			unsigned long size)
+{
+	u64 storage_size, remaining_size, max_size;
+	efi_status_t status;
+	const struct efivar_operations *fops = efivars->ops;
+
+	if (!efivars->ops->query_variable_info)
+		return EFI_UNSUPPORTED;
+
+	status = fops->query_variable_info(attributes, &storage_size,
+					   &remaining_size, &max_size);
+
+	if (status != EFI_SUCCESS)
+		return status;
+
+	if (!storage_size || size > remaining_size || size > max_size ||
+	    (remaining_size - size) < (storage_size / 2))
+		return EFI_OUT_OF_RESOURCES;
+
+	return status;
+}
+
+
+static efi_status_t
+check_var_size(struct efivars *efivars, u32 attributes, unsigned long size)
+{
+	efi_status_t status;
+	unsigned long flags;
+
+	spin_lock_irqsave(&efivars->lock, flags);
+	status = check_var_size_locked(efivars, attributes, size);
+	spin_unlock_irqrestore(&efivars->lock, flags);
+
+	return status;
+}
+
 static ssize_t
 efivar_guid_read(struct efivar_entry *entry, char *buf)
 {
@@ -546,11 +591,16 @@ efivar_store_raw(struct efivar_entry *entry, const char *buf, size_t count)
 	}
 
 	spin_lock_irq(&efivars->lock);
-	status = efivars->ops->set_variable(new_var->VariableName,
-					    &new_var->VendorGuid,
-					    new_var->Attributes,
-					    new_var->DataSize,
-					    new_var->Data);
+
+	status = check_var_size_locked(efivars, new_var->Attributes,
+	       new_var->DataSize + utf16_strsize(new_var->VariableName, 1024));
+
+	if (status == EFI_SUCCESS || status == EFI_UNSUPPORTED)
+		status = efivars->ops->set_variable(new_var->VariableName,
+						    &new_var->VendorGuid,
+						    new_var->Attributes,
+						    new_var->DataSize,
+						    new_var->Data);
 
 	spin_unlock_irq(&efivars->lock);
 
@@ -701,8 +751,7 @@ static ssize_t efivarfs_file_write(struct file *file,
 	u32 attributes;
 	struct inode *inode = file->f_mapping->host;
 	unsigned long datasize = count - sizeof(attributes);
-	unsigned long newdatasize;
-	u64 storage_size, remaining_size, max_size;
+	unsigned long newdatasize, varsize;
 	ssize_t bytes = 0;
 
 	if (count < sizeof(attributes))
@@ -721,28 +770,18 @@ static ssize_t efivarfs_file_write(struct file *file,
 	 * amounts of memory. Pick a default size of 64K if
 	 * QueryVariableInfo() isn't supported by the firmware.
 	 */
-	spin_lock_irq(&efivars->lock);
 
-	if (!efivars->ops->query_variable_info)
-		status = EFI_UNSUPPORTED;
-	else {
-		const struct efivar_operations *fops = efivars->ops;
-		status = fops->query_variable_info(attributes, &storage_size,
-						   &remaining_size, &max_size);
-	}
-
-	spin_unlock_irq(&efivars->lock);
+	varsize = datasize + utf16_strsize(var->var.VariableName, 1024);
+	status = check_var_size(efivars, attributes, varsize);
 
 	if (status != EFI_SUCCESS) {
 		if (status != EFI_UNSUPPORTED)
 			return efi_status_to_err(status);
 
-		remaining_size = 65536;
+		if (datasize > 65536)
+			return -ENOSPC;
 	}
 
-	if (datasize > remaining_size)
-		return -ENOSPC;
-
 	data = kmalloc(datasize, GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;
@@ -764,6 +803,19 @@ static ssize_t efivarfs_file_write(struct file *file,
 	 */
 	spin_lock_irq(&efivars->lock);
 
+	/*
+	 * Ensure that the available space hasn't shrunk below the safe level
+	 */
+
+	status = check_var_size_locked(efivars, attributes, varsize);
+
+	if (status != EFI_SUCCESS && status != EFI_UNSUPPORTED) {
+		spin_unlock_irq(&efivars->lock);
+		kfree(data);
+
+		return efi_status_to_err(status);
+	}
+
 	status = efivars->ops->set_variable(var->var.VariableName,
 					    &var->var.VendorGuid,
 					    attributes, datasize,
@@ -908,6 +960,48 @@ static struct inode *efivarfs_get_inode(struct super_block *sb,
 	return inode;
 }
 
+/*
+ * Return true if 'str' is a valid efivarfs filename of the form,
+ *
+ *	VariableName-12345678-1234-1234-1234-1234567891bc
+ */
+static bool efivarfs_valid_name(const char *str, int len)
+{
+	static const char dashes[GUID_LEN] = {
+		[8] = 1, [13] = 1, [18] = 1, [23] = 1
+	};
+	const char *s = str + len - GUID_LEN;
+	int i;
+
+	/*
+	 * We need a GUID, plus at least one letter for the variable name,
+	 * plus the '-' separator
+	 */
+	if (len < GUID_LEN + 2)
+		return false;
+
+	/* GUID must be preceded by a '-' */
+	if (*(s - 1) != '-')
+		return false;
+
+	/*
+	 * Validate that 's' is of the correct format, e.g.
+	 *
+	 *	12345678-1234-1234-1234-123456789abc
+	 */
+	for (i = 0; i < GUID_LEN; i++) {
+		if (dashes[i]) {
+			if (*s++ != '-')
+				return false;
+		} else {
+			if (!isxdigit(*s++))
+				return false;
+		}
+	}
+
+	return true;
+}
+
 static void efivarfs_hex_to_guid(const char *str, efi_guid_t *guid)
 {
 	guid->b[0] = hex_to_bin(str[6]) << 4 | hex_to_bin(str[7]);
@@ -936,11 +1030,7 @@ static int efivarfs_create(struct inode *dir, struct dentry *dentry,
 	struct efivar_entry *var;
 	int namelen, i = 0, err = 0;
 
-	/*
-	 * We need a GUID, plus at least one letter for the variable name,
-	 * plus the '-' separator
-	 */
-	if (dentry->d_name.len < GUID_LEN + 2)
+	if (!efivarfs_valid_name(dentry->d_name.name, dentry->d_name.len))
 		return -EINVAL;
 
 	inode = efivarfs_get_inode(dir->i_sb, dir, mode, 0);
@@ -1012,6 +1102,91 @@ static int efivarfs_unlink(struct inode *dir, struct dentry *dentry)
 	return -EINVAL;
 };
 
+/*
+ * Compare two efivarfs file names.
+ *
+ * An efivarfs filename is composed of two parts,
+ *
+ *	1. A case-sensitive variable name
+ *	2. A case-insensitive GUID
+ *
+ * So we need to perform a case-sensitive match on part 1 and a
+ * case-insensitive match on part 2.
+ */
+static int efivarfs_d_compare(const struct dentry *parent, const struct inode *pinode,
+			      const struct dentry *dentry, const struct inode *inode,
+			      unsigned int len, const char *str,
+			      const struct qstr *name)
+{
+	int guid = len - GUID_LEN;
+
+	if (name->len != len)
+		return 1;
+
+	/* Case-sensitive compare for the variable name */
+	if (memcmp(str, name->name, guid))
+		return 1;
+
+	/* Case-insensitive compare for the GUID */
+	return strncasecmp(name->name + guid, str + guid, GUID_LEN);
+}
+
+static int efivarfs_d_hash(const struct dentry *dentry,
+			   const struct inode *inode, struct qstr *qstr)
+{
+	unsigned long hash = init_name_hash();
+	const unsigned char *s = qstr->name;
+	unsigned int len = qstr->len;
+
+	if (!efivarfs_valid_name(s, len))
+		return -EINVAL;
+
+	while (len-- > GUID_LEN)
+		hash = partial_name_hash(*s++, hash);
+
+	/* GUID is case-insensitive. */
+	while (len--)
+		hash = partial_name_hash(tolower(*s++), hash);
+
+	qstr->hash = end_name_hash(hash);
+	return 0;
+}
+
+/*
+ * Retaining negative dentries for an in-memory filesystem just wastes
+ * memory and lookup time: arrange for them to be deleted immediately.
+ */
+static int efivarfs_delete_dentry(const struct dentry *dentry)
+{
+	return 1;
+}
+
+static struct dentry_operations efivarfs_d_ops = {
+	.d_compare = efivarfs_d_compare,
+	.d_hash = efivarfs_d_hash,
+	.d_delete = efivarfs_delete_dentry,
+};
+
+static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name)
+{
+	struct dentry *d;
+	struct qstr q;
+	int err;
+
+	q.name = name;
+	q.len = strlen(name);
+
+	err = efivarfs_d_hash(NULL, NULL, &q);
+	if (err)
+		return ERR_PTR(err);
+
+	d = d_alloc(parent, &q);
+	if (d)
+		return d;
+
+	return ERR_PTR(-ENOMEM);
+}
+
 static int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
 {
 	struct inode *inode = NULL;
@@ -1019,6 +1194,7 @@ static int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
 	struct efivar_entry *entry, *n;
 	struct efivars *efivars = &__efivars;
 	char *name;
+	int err = -ENOMEM;
 
 	efivarfs_sb = sb;
 
@@ -1027,6 +1203,7 @@ static int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
 	sb->s_blocksize_bits    = PAGE_CACHE_SHIFT;
 	sb->s_magic             = EFIVARFS_MAGIC;
 	sb->s_op                = &efivarfs_ops;
+	sb->s_d_op		= &efivarfs_d_ops;
 	sb->s_time_gran         = 1;
 
 	inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0);
@@ -1067,9 +1244,11 @@ static int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
 		if (!inode)
 			goto fail_name;
 
-		dentry = d_alloc_name(root, name);
-		if (!dentry)
+		dentry = efivarfs_alloc_dentry(root, name);
+		if (IS_ERR(dentry)) {
+			err = PTR_ERR(dentry);
 			goto fail_inode;
+		}
 
 		/* copied by the above to local storage in the dentry. */
 		kfree(name);
@@ -1084,7 +1263,7 @@ static int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
 
 		mutex_lock(&inode->i_mutex);
 		inode->i_private = entry;
-		i_size_write(inode, size+4);
+		i_size_write(inode, size + sizeof(entry->var.Attributes));
 		mutex_unlock(&inode->i_mutex);
 		d_add(dentry, inode);
 	}
@@ -1096,7 +1275,7 @@ fail_inode:
 fail_name:
 	kfree(name);
 fail:
-	return -ENOMEM;
+	return err;
 }
 
 static struct dentry *efivarfs_mount(struct file_system_type *fs_type,
@@ -1116,16 +1295,27 @@ static struct file_system_type efivarfs_type = {
 	.mount   = efivarfs_mount,
 	.kill_sb = efivarfs_kill_sb,
 };
+MODULE_ALIAS_FS("efivarfs");
+
+/*
+ * Handle negative dentry.
+ */
+static struct dentry *efivarfs_lookup(struct inode *dir, struct dentry *dentry,
+				      unsigned int flags)
+{
+	if (dentry->d_name.len > NAME_MAX)
+		return ERR_PTR(-ENAMETOOLONG);
+	d_add(dentry, NULL);
+	return NULL;
+}
 
 static const struct inode_operations efivarfs_dir_inode_operations = {
-	.lookup = simple_lookup,
+	.lookup = efivarfs_lookup,
 	.unlink = efivarfs_unlink,
 	.create = efivarfs_create,
 };
 
-static struct pstore_info efi_pstore_info;
-
-#ifdef CONFIG_PSTORE
+#ifdef CONFIG_EFI_VARS_PSTORE
 
 static int efi_pstore_open(struct pstore_info *psi)
 {
@@ -1215,7 +1405,6 @@ static int efi_pstore_write(enum pstore_type_id type,
 	efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
 	struct efivars *efivars = psi->data;
 	int i, ret = 0;
-	u64 storage_space, remaining_space, max_variable_size;
 	efi_status_t status = EFI_NOT_FOUND;
 	unsigned long flags;
 
@@ -1235,11 +1424,11 @@ static int efi_pstore_write(enum pstore_type_id type,
 	 * size: a size of logging data
 	 * DUMP_NAME_LEN * 2: a maximum size of variable name
 	 */
-	status = efivars->ops->query_variable_info(PSTORE_EFI_ATTRIBUTES,
-						   &storage_space,
-						   &remaining_space,
-						   &max_variable_size);
-	if (status || remaining_space < size + DUMP_NAME_LEN * 2) {
+
+	status = check_var_size_locked(efivars, PSTORE_EFI_ATTRIBUTES,
+					 size + DUMP_NAME_LEN * 2);
+
+	if (status) {
 		spin_unlock_irqrestore(&efivars->lock, flags);
 		*id = part;
 		return -ENOSPC;
@@ -1256,7 +1445,7 @@ static int efi_pstore_write(enum pstore_type_id type,
 
 	spin_unlock_irqrestore(&efivars->lock, flags);
 
-	if (reason == KMSG_DUMP_OOPS)
+	if (reason == KMSG_DUMP_OOPS && efivar_wq_enabled)
 		schedule_work(&efivar_work);
 
 	*id = part;
@@ -1329,38 +1518,6 @@ static int efi_pstore_erase(enum pstore_type_id type, u64 id, int count,
 
 	return 0;
 }
-#else
-static int efi_pstore_open(struct pstore_info *psi)
-{
-	return 0;
-}
-
-static int efi_pstore_close(struct pstore_info *psi)
-{
-	return 0;
-}
-
-static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type, int *count,
-			       struct timespec *timespec,
-			       char **buf, struct pstore_info *psi)
-{
-	return -1;
-}
-
-static int efi_pstore_write(enum pstore_type_id type,
-		enum kmsg_dump_reason reason, u64 *id,
-		unsigned int part, int count, size_t size,
-		struct pstore_info *psi)
-{
-	return 0;
-}
-
-static int efi_pstore_erase(enum pstore_type_id type, u64 id, int count,
-			    struct timespec time, struct pstore_info *psi)
-{
-	return 0;
-}
-#endif
 
 static struct pstore_info efi_pstore_info = {
 	.owner		= THIS_MODULE,
@@ -1372,6 +1529,24 @@ static struct pstore_info efi_pstore_info = {
 	.erase		= efi_pstore_erase,
 };
 
+static void efivar_pstore_register(struct efivars *efivars)
+{
+	efivars->efi_pstore_info = efi_pstore_info;
+	efivars->efi_pstore_info.buf = kmalloc(4096, GFP_KERNEL);
+	if (efivars->efi_pstore_info.buf) {
+		efivars->efi_pstore_info.bufsize = 1024;
+		efivars->efi_pstore_info.data = efivars;
+		spin_lock_init(&efivars->efi_pstore_info.buf_lock);
+		pstore_register(&efivars->efi_pstore_info);
+	}
+}
+#else
+static void efivar_pstore_register(struct efivars *efivars)
+{
+	return;
+}
+#endif
+
 static ssize_t efivar_create(struct file *filp, struct kobject *kobj,
 			     struct bin_attribute *bin_attr,
 			     char *buf, loff_t pos, size_t count)
@@ -1414,6 +1589,14 @@ static ssize_t efivar_create(struct file *filp, struct kobject *kobj,
 		return -EINVAL;
 	}
 
+	status = check_var_size_locked(efivars, new_var->Attributes,
+	       new_var->DataSize + utf16_strsize(new_var->VariableName, 1024));
+
+	if (status && status != EFI_UNSUPPORTED) {
+		spin_unlock_irq(&efivars->lock);
+		return efi_status_to_err(status);
+	}
+
 	/* now *really* create the variable via EFI */
 	status = efivars->ops->set_variable(new_var->VariableName,
 					    &new_var->VendorGuid,
@@ -1523,6 +1706,31 @@ static bool variable_is_present(efi_char16_t *variable_name, efi_guid_t *vendor)
 	return found;
 }
 
+/*
+ * Returns the size of variable_name, in bytes, including the
+ * terminating NULL character, or variable_name_size if no NULL
+ * character is found among the first variable_name_size bytes.
+ */
+static unsigned long var_name_strnsize(efi_char16_t *variable_name,
+				       unsigned long variable_name_size)
+{
+	unsigned long len;
+	efi_char16_t c;
+
+	/*
+	 * The variable name is, by definition, a NULL-terminated
+	 * string, so make absolutely sure that variable_name_size is
+	 * the value we expect it to be. If not, return the real size.
+	 */
+	for (len = 2; len <= variable_name_size; len += sizeof(c)) {
+		c = variable_name[(len / sizeof(c)) - 1];
+		if (!c)
+			break;
+	}
+
+	return min(len, variable_name_size);
+}
+
 static void efivar_update_sysfs_entries(struct work_struct *work)
 {
 	struct efivars *efivars = &__efivars;
@@ -1563,10 +1771,13 @@ static void efivar_update_sysfs_entries(struct work_struct *work)
 		if (!found) {
 			kfree(variable_name);
 			break;
-		} else
+		} else {
+			variable_name_size = var_name_strnsize(variable_name,
+							       variable_name_size);
 			efivar_create_sysfs_entry(efivars,
 						  variable_name_size,
 						  variable_name, &vendor);
+		}
 	}
 }
 
@@ -1765,6 +1976,35 @@ void unregister_efivars(struct efivars *efivars)
 }
 EXPORT_SYMBOL_GPL(unregister_efivars);
 
+/*
+ * Print a warning when duplicate EFI variables are encountered and
+ * disable the sysfs workqueue since the firmware is buggy.
+ */
+static void dup_variable_bug(efi_char16_t *s16, efi_guid_t *vendor_guid,
+			     unsigned long len16)
+{
+	size_t i, len8 = len16 / sizeof(efi_char16_t);
+	char *s8;
+
+	/*
+	 * Disable the workqueue since the algorithm it uses for
+	 * detecting new variables won't work with this buggy
+	 * implementation of GetNextVariableName().
+	 */
+	efivar_wq_enabled = false;
+
+	s8 = kzalloc(len8, GFP_KERNEL);
+	if (!s8)
+		return;
+
+	for (i = 0; i < len8; i++)
+		s8[i] = s16[i];
+
+	printk(KERN_WARNING "efivars: duplicate variable: %s-%pUl\n",
+	       s8, vendor_guid);
+	kfree(s8);
+}
+
 int register_efivars(struct efivars *efivars,
 		     const struct efivar_operations *ops,
 		     struct kobject *parent_kobj)
@@ -1813,6 +2053,24 @@ int register_efivars(struct efivars *efivars,
 						&vendor_guid);
 		switch (status) {
 		case EFI_SUCCESS:
+			variable_name_size = var_name_strnsize(variable_name,
+							       variable_name_size);
+
+			/*
+			 * Some firmware implementations return the
+			 * same variable name on multiple calls to
+			 * get_next_variable(). Terminate the loop
+			 * immediately as there is no guarantee that
+			 * we'll ever see a different variable name,
+			 * and may end up looping here forever.
+			 */
+			if (variable_is_present(variable_name, &vendor_guid)) {
+				dup_variable_bug(variable_name, &vendor_guid,
+						 variable_name_size);
+				status = EFI_NOT_FOUND;
+				break;
+			}
+
 			efivar_create_sysfs_entry(efivars,
 						  variable_name_size,
 						  variable_name,
@@ -1832,15 +2090,8 @@ int register_efivars(struct efivars *efivars,
 	if (error)
 		unregister_efivars(efivars);
 
-	efivars->efi_pstore_info = efi_pstore_info;
-
-	efivars->efi_pstore_info.buf = kmalloc(4096, GFP_KERNEL);
-	if (efivars->efi_pstore_info.buf) {
-		efivars->efi_pstore_info.bufsize = 1024;
-		efivars->efi_pstore_info.data = efivars;
-		spin_lock_init(&efivars->efi_pstore_info.buf_lock);
-		pstore_register(&efivars->efi_pstore_info);
-	}
+	if (!efivars_pstore_disable)
+		efivar_pstore_register(efivars);
 
 	register_filesystem(&efivarfs_type);