[PATCH v7 4/7] kernfs: use simple_xattrs for security attributes

[Ondrej Mosnacek <omosnace@xxxxxxxxxx>]

Replace the special handling of security xattrs with simple_xattrs, as
is already done for the trusted xattrs. This simplifies the code and
allows LSMs to use more than just a single xattr to do their business.

Signed-off-by: Ondrej Mosnacek <omosnace@xxxxxxxxxx>
---
 fs/kernfs/dir.c             |  7 ++---
 fs/kernfs/inode.c           | 55 ++-----------------------------------
 fs/kernfs/kernfs-internal.h |  2 --
 3 files changed, 4 insertions(+), 60 deletions(-)

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index e3e00d9be70d..6048f2ce85c4 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -531,12 +531,9 @@ void kernfs_put(struct kernfs_node *kn)
 
 	kfree_const(kn->name);
 
-	if (kn->iattr) {
-		if (kn->iattr->ia_secdata)
-			security_release_secctx(kn->iattr->ia_secdata,
-						kn->iattr->ia_secdata_len);
+	if (kn->iattr)
 		simple_xattrs_free(&kn->iattr->xattrs);
-	}
+
 	kfree(kn->iattr);
 	spin_lock(&kernfs_idr_lock);
 	idr_remove(&root->ino_idr, kn->id.ino);
diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c
index 7a7985961bbf..1acdfbf4b86a 100644
--- a/fs/kernfs/inode.c
+++ b/fs/kernfs/inode.c
@@ -137,23 +137,6 @@ out:
 	return error;
 }
 
-static int kernfs_node_setsecdata(struct kernfs_iattrs *attrs, void **secdata,
-				  u32 *secdata_len)
-{
-	void *old_secdata;
-	size_t old_secdata_len;
-
-	old_secdata = attrs->ia_secdata;
-	old_secdata_len = attrs->ia_secdata_len;
-
-	attrs->ia_secdata = *secdata;
-	attrs->ia_secdata_len = *secdata_len;
-
-	*secdata = old_secdata;
-	*secdata_len = old_secdata_len;
-	return 0;
-}
-
 ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size)
 {
 	struct kernfs_node *kn = kernfs_dentry_node(dentry);
@@ -189,15 +172,12 @@ static void kernfs_refresh_inode(struct kernfs_node *kn, struct inode *inode)
 	struct kernfs_iattrs *attrs = kn->iattr;
 
 	inode->i_mode = kn->mode;
-	if (attrs) {
+	if (attrs)
 		/*
 		 * kernfs_node has non-default attributes get them from
 		 * persistent copy in kernfs_node.
 		 */
 		set_inode_attr(inode, attrs);
-		security_inode_notifysecctx(inode, attrs->ia_secdata,
-					    attrs->ia_secdata_len);
-	}
 
 	if (kernfs_type(kn) == KERNFS_DIR)
 		set_nlink(inode, kn->dir.subdirs + 2);
@@ -345,41 +325,10 @@ static const struct xattr_handler kernfs_trusted_xattr_handler = {
 	.set = kernfs_xattr_set,
 };
 
-static int kernfs_security_xattr_set(const struct xattr_handler *handler,
-				     struct dentry *unused, struct inode *inode,
-				     const char *suffix, const void *value,
-				     size_t size, int flags)
-{
-	struct kernfs_node *kn = inode->i_private;
-	struct kernfs_iattrs *attrs;
-	void *secdata;
-	u32 secdata_len = 0;
-	int error;
-
-	attrs = kernfs_iattrs(kn);
-	if (!attrs)
-		return -ENOMEM;
-
-	error = security_inode_setsecurity(inode, suffix, value, size, flags);
-	if (error)
-		return error;
-	error = security_inode_getsecctx(inode, &secdata, &secdata_len);
-	if (error)
-		return error;
-
-	mutex_lock(&kernfs_mutex);
-	error = kernfs_node_setsecdata(attrs, &secdata, &secdata_len);
-	mutex_unlock(&kernfs_mutex);
-
-	if (secdata)
-		security_release_secctx(secdata, secdata_len);
-	return error;
-}
-
 static const struct xattr_handler kernfs_security_xattr_handler = {
 	.prefix = XATTR_SECURITY_PREFIX,
 	.get = kernfs_xattr_get,
-	.set = kernfs_security_xattr_set,
+	.set = kernfs_xattr_set,
 };
 
 const struct xattr_handler *kernfs_xattr_handlers[] = {
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 388c1193c4fa..0e1f1aa7df1e 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -24,8 +24,6 @@ struct kernfs_iattrs {
 	struct timespec64	ia_atime;
 	struct timespec64	ia_mtime;
 	struct timespec64	ia_ctime;
-	void			*ia_secdata;
-	u32			ia_secdata_len;
 
 	struct simple_xattrs	xattrs;
 };
-- 
2.20.1