linux-kernel - [PATCH 16/16] vfs: return -EOPNOTSUPP for fscaps from vfs

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Message-Id: <20231129-idmap-fscap-refactor-v1-16-da5a26058a5b@kernel.org>
Date:   Wed, 29 Nov 2023 15:50:34 -0600
From:   "Seth Forshee (DigitalOcean)" <sforshee@...nel.org>
To:     Christian Brauner <brauner@...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>,
        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,
        linux-unionfs@...r.kernel.org,
        "Seth Forshee (DigitalOcean)" <sforshee@...nel.org>
Subject: [PATCH 16/16] 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 372644b15457..4b779779ad8c 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -540,6 +540,9 @@ vfs_setxattr(struct mnt_idmap *idmap, struct dentry *dentry,
 	const void  *orig_value = value;
 	int error;
 
+	if (!strcmp(name, XATTR_NAME_CAPS))
+		return -EOPNOTSUPP;
+
 retry_deleg:
 	inode_lock(inode);
 	error = __vfs_setxattr_locked(idmap, dentry, name, value, size,
@@ -655,6 +658,9 @@ vfs_getxattr(struct mnt_idmap *idmap, struct dentry *dentry,
 	struct inode *inode = dentry->d_inode;
 	int error;
 
+	if (!strcmp(name, XATTR_NAME_CAPS))
+		return -EOPNOTSUPP;
+
 	error = xattr_permission(idmap, inode, name, MAY_READ);
 	if (error)
 		return error;
@@ -794,6 +800,9 @@ vfs_removexattr(struct mnt_idmap *idmap, struct dentry *dentry,
 	struct inode *delegated_inode = NULL;
 	int error;
 
+	if (!strcmp(name, XATTR_NAME_CAPS))
+		return -EOPNOTSUPP;
+
 retry_deleg:
 	inode_lock(inode);
 	error = __vfs_removexattr_locked(idmap, dentry,

-- 
2.43.0