From 0c542edde3cecc99b180a440ae33dcb7f28642ce Mon Sep 17 00:00:00 2001 From: Jeremy Kerr Date: Fri, 5 Oct 2012 13:54:56 +0800 Subject: [PATCH] efi: Handle deletions and size changes in efivarfs_write_file A write to an efivarfs file will not always result in a variable of 'count' size after the EFI SetVariable() call. We may have appended to the existing data (ie, with the EFI_VARIABLE_APPEND_WRITE attribute), or even have deleted the variable (with an authenticated variable update, with a zero datasize). This change re-reads the updated variable from firmware, to check for size changes and deletions. In the latter case, we need to drop the dentry. Signed-off-by: Jeremy Kerr Signed-off-by: Matt Fleming --- drivers/firmware/efivars.c | 49 ++++++++++++++++++++++++++++++++++++---------- 1 file changed, 39 insertions(+), 10 deletions(-) diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c index b605c4849772..d7658b4a5010 100644 --- a/drivers/firmware/efivars.c +++ b/drivers/firmware/efivars.c @@ -658,6 +658,7 @@ static ssize_t efivarfs_file_write(struct file *file, u32 attributes; struct inode *inode = file->f_mapping->host; int datasize = count - sizeof(attributes); + unsigned long newdatasize; if (count < sizeof(attributes)) return -EINVAL; @@ -696,32 +697,60 @@ static ssize_t efivarfs_file_write(struct file *file, switch (status) { case EFI_SUCCESS: - mutex_lock(&inode->i_mutex); - i_size_write(inode, count); - mutex_unlock(&inode->i_mutex); break; case EFI_INVALID_PARAMETER: count = -EINVAL; - break; + goto out; case EFI_OUT_OF_RESOURCES: count = -ENOSPC; - break; + goto out; case EFI_DEVICE_ERROR: count = -EIO; - break; + goto out; case EFI_WRITE_PROTECTED: count = -EROFS; - break; + goto out; case EFI_SECURITY_VIOLATION: count = -EACCES; - break; + goto out; case EFI_NOT_FOUND: count = -ENOENT; - break; + goto out; default: count = -EINVAL; - break; + goto out; } + + /* + * Writing to the variable may have caused a change in size (which + * could either be an append or an overwrite), or the variable to be + * deleted. Perform a GetVariable() so we can tell what actually + * happened. + */ + newdatasize = 0; + status = efivars->ops->get_variable(var->var.VariableName, + &var->var.VendorGuid, + NULL, &newdatasize, + NULL); + + if (status == EFI_BUFFER_TOO_SMALL) { + 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); + drop_nlink(inode); + dput(file->f_dentry); + + } else { + pr_warn("efivarfs: inconsistent EFI variable implementation? " + "status = %lx\n", status); + } + out: kfree(data); -- 2.11.0