linux-kernel - [PATCH v2 25/25] vfs: return -EOPNOTSUPP for fscaps from vfs

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Message-Id: <20240221-idmap-fscap-refactor-v2-25-3039364623bd@kernel.org>
Date: Wed, 21 Feb 2024 15:24:56 -0600
From: "Seth Forshee (DigitalOcean)" <sforshee@...nel.org>
To: Christian Brauner <brauner@...nel.org>, 
 Seth Forshee <sforshee@...nel.org>, Serge Hallyn <serge@...lyn.com>, 
 Paul Moore <paul@...l-moore.com>, Eric Paris <eparis@...hat.com>, 
 James Morris <jmorris@...ei.org>, Alexander Viro <viro@...iv.linux.org.uk>, 
 Jan Kara <jack@...e.cz>, Stephen Smalley <stephen.smalley.work@...il.com>, 
 Ondrej Mosnacek <omosnace@...hat.com>, 
 Casey Schaufler <casey@...aufler-ca.com>, Mimi Zohar <zohar@...ux.ibm.com>, 
 Roberto Sassu <roberto.sassu@...wei.com>, 
 Dmitry Kasatkin <dmitry.kasatkin@...il.com>, 
 Eric Snowberg <eric.snowberg@...cle.com>, 
 "Matthew Wilcox (Oracle)" <willy@...radead.org>, 
 Jonathan Corbet <corbet@....net>, Miklos Szeredi <miklos@...redi.hu>, 
 Amir Goldstein <amir73il@...il.com>
Cc: linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org, 
 linux-security-module@...r.kernel.org, audit@...r.kernel.org, 
 selinux@...r.kernel.org, linux-integrity@...r.kernel.org, 
 linux-doc@...r.kernel.org, linux-unionfs@...r.kernel.org
Subject: [PATCH v2 25/25] vfs: return -EOPNOTSUPP for fscaps from
 vfs_*xattr()

Now that the new vfs-level interfaces are fully supported and all code
has been converted to use them, stop permitting use of the top-level vfs
xattr interfaces for capabilities xattrs. Unlike with ACLs we still need
to be able to work with fscaps xattrs using lower-level interfaces in a
handful of places, so only use of the top-level xattr interfaces is
restricted.

Signed-off-by: Seth Forshee (DigitalOcean) <sforshee@...nel.org>
---
 fs/xattr.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/fs/xattr.c b/fs/xattr.c
index 30eff6bc4f6d..2b8214c9534f 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -534,6 +534,9 @@ vfs_setxattr(struct mnt_idmap *idmap, struct dentry *dentry,
 	const void  *orig_value = value;
 	int error;
 
+	if (WARN_ON_ONCE(is_fscaps_xattr(name)))
+		return -EOPNOTSUPP;
+
 retry_deleg:
 	inode_lock(inode);
 	error = __vfs_setxattr_locked(idmap, dentry, name, value, size,
@@ -649,6 +652,9 @@ vfs_getxattr(struct mnt_idmap *idmap, struct dentry *dentry,
 	struct inode *inode = dentry->d_inode;
 	int error;
 
+	if (WARN_ON_ONCE(is_fscaps_xattr(name)))
+		return -EOPNOTSUPP;
+
 	error = xattr_permission(idmap, inode, name, MAY_READ);
 	if (error)
 		return error;
@@ -788,6 +794,9 @@ vfs_removexattr(struct mnt_idmap *idmap, struct dentry *dentry,
 	struct inode *delegated_inode = NULL;
 	int error;
 
+	if (WARN_ON_ONCE(is_fscaps_xattr(name)))
+		return -EOPNOTSUPP;
+
 retry_deleg:
 	inode_lock(inode);
 	error = __vfs_removexattr_locked(idmap, dentry,

-- 
2.43.0