Commit 121ab822 authored by Vivek Goyal's avatar Vivek Goyal Committed by Paul Moore

security,overlayfs: Provide security hook for copy up of xattrs for overlay file

Provide a security hook which is called when xattrs of a file are being
copied up. This hook is called once for each xattr and LSM can return
0 if the security module wants the xattr to be copied up, 1 if the
security module wants the xattr to be discarded on the copy, -EOPNOTSUPP
if the security module does not handle/manage the xattr, or a -errno
upon an error.
Signed-off-by: default avatarDavid Howells <[email protected]>
Signed-off-by: Vivek Goyal's avatarVivek Goyal <[email protected]>
Acked-by: Stephen Smalley's avatarStephen Smalley <[email protected]>
[PM: whitespace cleanup for checkpatch.pl]
Signed-off-by: default avatarPaul Moore <[email protected]>
parent 56909eb3
......@@ -103,6 +103,13 @@ int ovl_copy_xattr(struct dentry *old, struct dentry *new)
goto retry;
}
error = security_inode_copy_up_xattr(name);
if (error < 0 && error != -EOPNOTSUPP)
break;
if (error == 1) {
error = 0;
continue; /* Discard */
}
error = vfs_setxattr(new, name, value, size, 0);
if (error)
break;
......
......@@ -410,6 +410,14 @@
* @src indicates the union dentry of file that is being copied up.
* @new pointer to pointer to return newly allocated creds.
* Returns 0 on success or a negative error code on error.
* @inode_copy_up_xattr:
* Filter the xattrs being copied up when a unioned file is copied
* up from a lower layer to the union/overlay layer.
* @name indicates the name of the xattr.
* Returns 0 to accept the xattr, 1 to discard the xattr, -EOPNOTSUPP if
* security module does not know about attribute or a negative error code
* to abort the copy up. Note that the caller is responsible for reading
* and writing the xattrs as this hook is merely a filter.
*
* Security hooks for file operations
*
......@@ -1435,6 +1443,7 @@ union security_list_options {
size_t buffer_size);
void (*inode_getsecid)(struct inode *inode, u32 *secid);
int (*inode_copy_up)(struct dentry *src, struct cred **new);
int (*inode_copy_up_xattr)(const char *name);
int (*file_permission)(struct file *file, int mask);
int (*file_alloc_security)(struct file *file);
......@@ -1707,6 +1716,7 @@ struct security_hook_heads {
struct list_head inode_listsecurity;
struct list_head inode_getsecid;
struct list_head inode_copy_up;
struct list_head inode_copy_up_xattr;
struct list_head file_permission;
struct list_head file_alloc_security;
struct list_head file_free_security;
......
......@@ -283,6 +283,7 @@ int security_inode_setsecurity(struct inode *inode, const char *name, const void
int security_inode_listsecurity(struct inode *inode, char *buffer, size_t buffer_size);
void security_inode_getsecid(struct inode *inode, u32 *secid);
int security_inode_copy_up(struct dentry *src, struct cred **new);
int security_inode_copy_up_xattr(const char *name);
int security_file_permission(struct file *file, int mask);
int security_file_alloc(struct file *file);
void security_file_free(struct file *file);
......@@ -764,6 +765,11 @@ static inline int security_inode_copy_up(struct dentry *src, struct cred **new)
return 0;
}
static inline int security_inode_copy_up_xattr(const char *name)
{
return -EOPNOTSUPP;
}
static inline int security_file_permission(struct file *file, int mask)
{
return 0;
......
......@@ -754,6 +754,12 @@ int security_inode_copy_up(struct dentry *src, struct cred **new)
}
EXPORT_SYMBOL(security_inode_copy_up);
int security_inode_copy_up_xattr(const char *name)
{
return call_int_hook(inode_copy_up_xattr, -EOPNOTSUPP, name);
}
EXPORT_SYMBOL(security_inode_copy_up_xattr);
int security_file_permission(struct file *file, int mask)
{
int ret;
......@@ -1692,6 +1698,8 @@ struct security_hook_heads security_hook_heads = {
LIST_HEAD_INIT(security_hook_heads.inode_getsecid),
.inode_copy_up =
LIST_HEAD_INIT(security_hook_heads.inode_copy_up),
.inode_copy_up_xattr =
LIST_HEAD_INIT(security_hook_heads.inode_copy_up_xattr),
.file_permission =
LIST_HEAD_INIT(security_hook_heads.file_permission),
.file_alloc_security =
......
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