From e499214ce3ef50c50522719e753a1ffc928c2ec1 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Wed, 1 Feb 2023 14:15:01 +0100 Subject: [PATCH] acl: don't depend on IOP_XATTR All codepaths that don't want to implement POSIX ACLs should simply not implement the associated inode operations instead of relying on IOP_XATTR. That's the case for all filesystems today. For vfs_listxattr() all filesystems that explicitly turn of xattrs for a given inode all set inode->i_op to a dedicated set of inode operations that doesn't implement ->listxattr(). We can remove the dependency of vfs_listxattr() on IOP_XATTR. Removing this dependency will allow us to decouple POSIX ACLs from IOP_XATTR and they can still be listed even if no other xattr handlers are implemented. Otherwise we would have to implement elaborate schemes to raise IOP_XATTR even if sb->s_xattr is set to NULL. Signed-off-by: Christian Brauner (Microsoft) --- fs/posix_acl.c | 12 ++++-------- fs/xattr.c | 25 ++++++++++++++++++++++++- 2 files changed, 28 insertions(+), 9 deletions(-) diff --git a/fs/posix_acl.c b/fs/posix_acl.c index e262c428f869..7fa1b738bbab 100644 --- a/fs/posix_acl.c +++ b/fs/posix_acl.c @@ -1131,12 +1131,10 @@ retry_deleg: if (error) goto out_inode_unlock; - if (inode->i_opflags & IOP_XATTR) + if (likely(!is_bad_inode(inode))) error = set_posix_acl(idmap, dentry, acl_type, kacl); - else if (unlikely(is_bad_inode(inode))) - error = -EIO; else - error = -EOPNOTSUPP; + error = -EIO; if (!error) { fsnotify_xattr(dentry); evm_inode_post_set_acl(dentry, acl_name, kacl); @@ -1241,12 +1239,10 @@ retry_deleg: if (error) goto out_inode_unlock; - if (inode->i_opflags & IOP_XATTR) + if (likely(!is_bad_inode(inode))) error = set_posix_acl(idmap, dentry, acl_type, NULL); - else if (unlikely(is_bad_inode(inode))) - error = -EIO; else - error = -EOPNOTSUPP; + error = -EIO; if (!error) { fsnotify_xattr(dentry); evm_inode_post_remove_acl(idmap, dentry, acl_name); diff --git a/fs/xattr.c b/fs/xattr.c index 95bb6b30ab13..fcf67d80d7f9 100644 --- a/fs/xattr.c +++ b/fs/xattr.c @@ -458,6 +458,28 @@ nolsm: } EXPORT_SYMBOL_GPL(vfs_getxattr); +/** + * vfs_listxattr - retrieve \0 separated list of xattr names + * @dentry: the dentry from whose inode the xattr names are retrieved + * @list: buffer to store xattr names into + * @size: size of the buffer + * + * This function returns the names of all xattrs associated with the + * inode of @dentry. + * + * Note, for legacy reasons the vfs_listxattr() function lists POSIX + * ACLs as well. Since POSIX ACLs are decoupled from IOP_XATTR the + * vfs_listxattr() function doesn't check for this flag since a + * filesystem could implement POSIX ACLs without implementing any other + * xattrs. + * + * However, since all codepaths that remove IOP_XATTR also assign of + * inode operations that either don't implement or implement a stub + * ->listxattr() operation. + * + * Return: On success, the size of the buffer that was used. On error a + * negative error code. + */ ssize_t vfs_listxattr(struct dentry *dentry, char *list, size_t size) { @@ -467,7 +489,8 @@ vfs_listxattr(struct dentry *dentry, char *list, size_t size) error = security_inode_listxattr(dentry); if (error) return error; - if (inode->i_op->listxattr && (inode->i_opflags & IOP_XATTR)) { + + if (inode->i_op->listxattr) { error = inode->i_op->listxattr(dentry, list, size); } else { error = security_inode_listsecurity(inode, list, size);