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

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 <dhowells@redhat.com>
Signed-off-by: default avatarVivek Goyal <vgoyal@redhat.com>
Acked-by: default avatarStephen Smalley <sds@tycho.nsa.gov>
[PM: whitespace cleanup for checkpatch.pl]
Signed-off-by: default avatarPaul Moore <paul@paul-moore.com>
parent 56909eb3

fs/overlayfs/copy_up.c

+7 −0
Original line number Diff line number Diff line
@@ -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;

include/linux/lsm_hooks.h

+10 −0
Original line number Diff line number Diff line
@@ -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;

include/linux/security.h

+6 −0
Original line number Diff line number Diff line
@@ -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;

security/security.c

+8 −0
Original line number Diff line number Diff line
@@ -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 =