[v4,2/5] kernfs: use simple_xattrs for security attributes

Commit Message

Ondrej Mosnacek Feb. 5, 2019, 8:59 a.m. UTC

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 <[e-mail]>
---
 fs/kernfs/dir.c             |   7 ++-
 fs/kernfs/inode.c           | 100 +++++++++++++++---------------------
 fs/kernfs/kernfs-internal.h |   5 +-
 3 files changed, 46 insertions(+), 66 deletions(-)

Patch

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 4ca0b5c18192..ad7e3356bcc5 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -532,11 +532,10 @@  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);
-		simple_xattrs_free(&kn->iattr->xattrs);
+		simple_xattrs_free(&kn->iattr->xattrs_trusted);
+		simple_xattrs_free(&kn->iattr->xattrs_security);
 	}
+
 	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 80cebcd94c90..f0e2cb4379c0 100644
--- a/fs/kernfs/inode.c
+++ b/fs/kernfs/inode.c
@@ -56,7 +56,8 @@  static struct kernfs_iattrs *kernfs_iattrs(struct kernfs_node *kn)
 	iattrs->ia_mtime = iattrs->ia_atime;
 	iattrs->ia_ctime = iattrs->ia_atime;
 
-	simple_xattrs_init(&kn->iattr->xattrs);
+	simple_xattrs_init(&kn->iattr->xattrs_trusted);
+	simple_xattrs_init(&kn->iattr->xattrs_security);
 out_unlock:
 	ret = kn->iattr;
 	mutex_unlock(&iattr_mutex);
@@ -135,33 +136,31 @@  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);
+	struct inode *inode = d_inode(dentry);
 	struct kernfs_iattrs *attrs;
+	ssize_t ret, length = 0;
 
 	attrs = kernfs_iattrs(kn);
 	if (!attrs)
 		return -ENOMEM;
 
-	return simple_xattr_list(d_inode(dentry), &attrs->xattrs, buf, size);
+	ret = simple_xattr_list(inode, &attrs->xattrs_trusted, buf, size);
+	if (ret < 0)
+		return ret;
+	length += ret;
+
+	buf += ret;
+	size -= ret;
+
+	ret = simple_xattr_list(inode, &attrs->xattrs_security, buf, size);
+	if (ret < 0)
+		return ret;
+	length += ret;
+
+	return length;
 }
 
 static inline void set_default_inode_attr(struct inode *inode, umode_t mode)
@@ -186,15 +185,12 @@  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->ia_iattr);
-		security_inode_notifysecctx(inode, attrs->ia_secdata,
-					    attrs->ia_secdata_len);
-	}
 
 	if (kernfs_type(kn) == KERNFS_DIR)
 		set_nlink(inode, kn->dir.subdirs + 2);
@@ -305,19 +301,29 @@  int kernfs_iop_permission(struct inode *inode, int mask)
 	return generic_permission(inode, mask);
 }
 
+static const struct xattr_handler kernfs_trusted_xattr_handler;
+static const struct xattr_handler kernfs_security_xattr_handler;
+
 static int kernfs_xattr_get(const struct xattr_handler *handler,
 			    struct dentry *unused, struct inode *inode,
 			    const char *suffix, void *value, size_t size)
 {
-	const char *name = xattr_full_name(handler, suffix);
 	struct kernfs_node *kn = inode->i_private;
 	struct kernfs_iattrs *attrs;
+	struct simple_xattrs *xattrs;
 
 	attrs = kernfs_iattrs(kn);
 	if (!attrs)
 		return -ENOMEM;
 
-	return simple_xattr_get(&attrs->xattrs, name, value, size);
+	if (handler == &kernfs_trusted_xattr_handler)
+		xattrs = &attrs->xattrs_trusted;
+	else if (handler == &kernfs_security_xattr_handler)
+		xattrs = &attrs->xattrs_security;
+	else
+		return -EINVAL;
+
+	return simple_xattr_get(xattrs, suffix, value, size);
 }
 
 static int kernfs_xattr_set(const struct xattr_handler *handler,
@@ -325,15 +331,22 @@  static int kernfs_xattr_set(const struct xattr_handler *handler,
 			    const char *suffix, const void *value,
 			    size_t size, int flags)
 {
-	const char *name = xattr_full_name(handler, suffix);
 	struct kernfs_node *kn = inode->i_private;
 	struct kernfs_iattrs *attrs;
+	struct simple_xattrs *xattrs;
 
 	attrs = kernfs_iattrs(kn);
 	if (!attrs)
 		return -ENOMEM;
 
-	return simple_xattr_set(&attrs->xattrs, name, value, size, flags);
+	if (handler == &kernfs_trusted_xattr_handler)
+		xattrs = &attrs->xattrs_trusted;
+	else if (handler == &kernfs_security_xattr_handler)
+		xattrs = &attrs->xattrs_security;
+	else
+		return -EINVAL;
+
+	return simple_xattr_set(xattrs, suffix, value, size, flags);
 }
 
 static const struct xattr_handler kernfs_trusted_xattr_handler = {
@@ -342,41 +355,10 @@  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 3d83b114bb08..93bf1dcd0306 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -20,10 +20,9 @@ 
 
 struct kernfs_iattrs {
 	struct iattr		ia_iattr;
-	void			*ia_secdata;
-	u32			ia_secdata_len;
 
-	struct simple_xattrs	xattrs;
+	struct simple_xattrs	xattrs_trusted;
+	struct simple_xattrs	xattrs_security;
 };
 
 /* +1 to avoid triggering overflow warning when negating it */