Merge tag 'efi-for-3.9-rc2' into x86/urgent

EFI changes for v3.9-rc2,

  * Make the EFI variable code more paranoid about running out of
    space in NVRAM, since this is the root cause of the recent issue
    where machines refuse to boot - from Matthew Garrett.

  * Some efivarfs patches that fix regressions introduced in v3.9-rc1.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

1 files changed, 96 insertions, 34 deletions

diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index 7320bf891706..bea32d1ef7d5 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -426,6 +426,44 @@ 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)
 {
@@ -547,11 +585,16 @@ 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);
 
@@ -702,8 +745,7 @@ 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))
@@ -722,28 +764,18 @@ 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;
@@ -765,6 +797,19 @@ 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,
@@ -929,8 +974,8 @@ static bool efivarfs_valid_name(const char *str, int len)
 	if (len < GUID_LEN + 2)
 		return false;
 
-	/* GUID should be right after the first '-' */
-	if (s - 1 != strchr(str, '-'))
+	/* GUID must be preceded by a '-' */
+	if (*(s - 1) != '-')
 		return false;
 
 	/*
@@ -1118,15 +1163,22 @@ static struct dentry_operations efivarfs_d_ops = {
 
 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);
 
-	if (efivarfs_d_hash(NULL, NULL, &q))
-		return NULL;
+	err = efivarfs_d_hash(NULL, NULL, &q);
+	if (err)
+		return ERR_PTR(err);
+
+	d = d_alloc(parent, &q);
+	if (d)
+		return d;
 
-	return d_alloc(parent, &q);
+	return ERR_PTR(-ENOMEM);
 }
 
 static int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
@@ -1136,6 +1188,7 @@ 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;
 
@@ -1186,8 +1239,10 @@ static int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
 			goto fail_name;
 
 		dentry = efivarfs_alloc_dentry(root, name);
-		if (!dentry)
+		if (IS_ERR(dentry)) {
+			err = PTR_ERR(dentry);
 			goto fail_inode;
+		}
 
 		/* copied by the above to local storage in the dentry. */
 		kfree(name);
@@ -1214,7 +1269,7 @@ fail_inode:
 fail_name:
 	kfree(name);
 fail:
-	return -ENOMEM;
+	return err;
 }
 
 static struct dentry *efivarfs_mount(struct file_system_type *fs_type,
@@ -1345,7 +1400,6 @@ 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;
 
@@ -1365,11 +1419,11 @@ 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;
@@ -1544,6 +1598,14 @@ 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,