Re: [PATCH] anon_inode: use a proper mode internally

[Christian Brauner]

> Anyway, I'm finishing the patch and testing tomorrow and will send out
> with all the things I mentioned (unless I find out I'm wrong).

Found my notes about this. I knew I had notes about this somewhere...
It isn't possible to execute anoymous inodes because you cannot open
them. That includes stuff like:

execveat(fd_anon_inode, "", NULL, NULL, AT_EMPTY_PATH)

Look, anonymous inodes have inode->f_op set to no_open_fops which sets
no_open() which returns ENXIO. That means any call to do_dentry_open()
which is the endpoint of the do_open_execat() will fail. There's no
chance to execute an anonymous inode. Unless a given subsystem overrides
it ofc.

I still agree that we need to be more coherent about this and we need to
improve various semantical quirks I pointed out. But the exec problem
isn't really an issue so the patch itself still seems correct to me.