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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) <brauner@kernel.org>
This commit is contained in:
Christian Brauner 2023-02-01 14:15:01 +01:00 committed by Christian Brauner (Microsoft)
parent a1fbb60734
commit e499214ce3
No known key found for this signature in database
GPG Key ID: 91C61BC06578DCA2
2 changed files with 28 additions and 9 deletions
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12
fs/posix_acl.c
View File

@ -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);

25
fs/xattr.c
View File

@ -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);