Re: [PATCH 01/18] vfs: add miscattr ops

[Miklos Szeredi]

On Tue, Mar 23, 2021 at 1:24 AM Eric Biggers <ebiggers@xxxxxxxxxx> wrote:

> > +int vfs_miscattr_set(struct dentry *dentry, struct miscattr *ma)
> > +{
> > +     struct inode *inode = d_inode(dentry);
> > +     struct miscattr old_ma = {};
> > +     int err;
> > +
> > +     if (d_is_special(dentry))
> > +             return -ENOTTY;
> > +
> > +     if (!inode->i_op->miscattr_set)
> > +             return -ENOIOCTLCMD;
> > +
> > +     if (!inode_owner_or_capable(inode))
> > +             return -EPERM;
>
> Shouldn't this be EACCES, not EPERM?

$ git diff master.. | grep -C1 inode_owner_or_capable | grep
"^-.*\(EPERM\|EACCES\)" | cut -d- -f3 | sort | uniq -c
     12 EACCES;
      4 EPERM;

So EACCES would win if this was a democracy.  However:

"[EACCES]
Permission denied. An attempt was made to access a file in a way
forbidden by its file access permissions."

"[EPERM]
Operation not permitted. An attempt was made to perform an operation
limited to processes with appropriate privileges or to the owner of a
file or other resource."

The EPERM description matches the semantics of
inode_owner_or_capable() exactly.  It's a pretty clear choice.

Thanks,
Miklos