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efivarfs: Implement exclusive access for {get,set}_variable

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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 <jeremy.kerr@canonical.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
This commit is contained in:
Jeremy Kerr 2012-10-11 21:19:11 +08:00 committed by Matt Fleming
parent 5ba6e2919b
commit f5f6a60ad5
1 changed files with 43 additions and 25 deletions
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68
drivers/firmware/efivars.c
View File

@ -690,35 +690,45 @@ 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;
}
/*
@ -734,12 +744,12 @@ 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);
@ -747,6 +757,7 @@ 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);
}
@ -768,9 +779,11 @@ 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;
@ -780,10 +793,13 @@ 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;
@ -1004,11 +1020,13 @@ 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;