Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758664Ab2JKNTZ (ORCPT ); Thu, 11 Oct 2012 09:19:25 -0400 Received: from ozlabs.org ([203.10.76.45]:38325 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758568Ab2JKNTS (ORCPT ); Thu, 11 Oct 2012 09:19:18 -0400 Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [PATCH] efivarfs: Implement exclusive access for {get,set}_variable Message-Id: <1349961551.174484.910885224391.1.gpush@pecola> To: Matt Fleming Cc: linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, Andy Whitcroft , Matthew Garrett From: Jeremy Kerr Date: Thu, 11 Oct 2012 21:19:11 +0800 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4260 Lines: 154 Currently, efivarfs does not enforce exclusion over the get_variable and set_variable operations. Section 7.1 of UEFI requires us to only allow a single processor to enter {get,set}_variable services at once. This change acquires the efivars->lock over calls to these operations from the efivarfs paths. Signed-off-by: Jeremy Kerr --- drivers/firmware/efivars.c | 68 +++++++++++++++++++++++-------------- 1 file changed, 43 insertions(+), 25 deletions(-) diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c index 5765664..a86eb55 100644 --- a/drivers/firmware/efivars.c +++ b/drivers/firmware/efivars.c @@ -679,35 +679,45 @@ static ssize_t efivarfs_file_write(struct file *file, goto out; } + /* + * The lock here protects the get_variable call, the conditional + * set_variable call, and removal of the variable from the efivars + * list (in the case of an authenticated delete). + */ + spin_lock(&efivars->lock); + status = efivars->ops->set_variable(var->var.VariableName, &var->var.VendorGuid, attributes, datasize, data); - switch (status) { - case EFI_SUCCESS: - break; - case EFI_INVALID_PARAMETER: - count = -EINVAL; - goto out; - case EFI_OUT_OF_RESOURCES: - count = -ENOSPC; - goto out; - case EFI_DEVICE_ERROR: - count = -EIO; - goto out; - case EFI_WRITE_PROTECTED: - count = -EROFS; - goto out; - case EFI_SECURITY_VIOLATION: - count = -EACCES; - goto out; - case EFI_NOT_FOUND: - count = -ENOENT; - goto out; - default: - count = -EINVAL; - goto out; + if (status != EFI_SUCCESS) { + spin_unlock(&efivars->lock); + kfree(data); + + switch (status) { + case EFI_INVALID_PARAMETER: + count = -EINVAL; + break; + case EFI_OUT_OF_RESOURCES: + count = -ENOSPC; + break; + case EFI_DEVICE_ERROR: + count = -EIO; + break; + case EFI_WRITE_PROTECTED: + count = -EROFS; + break; + case EFI_SECURITY_VIOLATION: + count = -EACCES; + break; + case EFI_NOT_FOUND: + count = -ENOENT; + break; + default: + count = -EINVAL; + } + return count; } /* @@ -723,12 +733,12 @@ static ssize_t efivarfs_file_write(struct file *file, NULL); if (status == EFI_BUFFER_TOO_SMALL) { + spin_unlock(&efivars->lock); mutex_lock(&inode->i_mutex); i_size_write(inode, newdatasize + sizeof(attributes)); mutex_unlock(&inode->i_mutex); } else if (status == EFI_NOT_FOUND) { - spin_lock(&efivars->lock); list_del(&var->list); spin_unlock(&efivars->lock); efivar_unregister(var); @@ -736,6 +746,7 @@ static ssize_t efivarfs_file_write(struct file *file, dput(file->f_dentry); } else { + spin_unlock(&efivars->lock); pr_warn("efivarfs: inconsistent EFI variable implementation? " "status = %lx\n", status); } @@ -757,9 +768,11 @@ static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf, void *data; ssize_t size = 0; + spin_lock(&efivars->lock); status = efivars->ops->get_variable(var->var.VariableName, &var->var.VendorGuid, &attributes, &datasize, NULL); + spin_unlock(&efivars->lock); if (status != EFI_BUFFER_TOO_SMALL) return 0; @@ -769,10 +782,13 @@ static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf, if (!data) return 0; + spin_lock(&efivars->lock); status = efivars->ops->get_variable(var->var.VariableName, &var->var.VendorGuid, &attributes, &datasize, (data + 4)); + spin_unlock(&efivars->lock); + if (status != EFI_SUCCESS) goto out_free; @@ -993,11 +1009,13 @@ int efivarfs_fill_super(struct super_block *sb, void *data, int silent) /* copied by the above to local storage in the dentry. */ kfree(name); + spin_lock(&efivars->lock); efivars->ops->get_variable(entry->var.VariableName, &entry->var.VendorGuid, &entry->var.Attributes, &size, NULL); + spin_unlock(&efivars->lock); mutex_lock(&inode->i_mutex); inode->i_private = entry; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/