Re: Fwd: [bug #17877] Invalid "No such file or directory" error on filesystem without stable inode numbers

[Miklos Szeredi]

> For example, consider the classic symlink attack.
> We're not supposed to follow symlinks and our system lacks support
> for open's O_NOFOLLOW flag.  So we lstat the target directory,
> determine that it is indeed a directory, then open it.  But between
> the lstat and the open, someone moved it aside and replaced it with
> a symlink to another directory.  The only way to detect that is to
> compare dev/inode pairs before and after.

OK, but for systems which do have O_NOFOLLOW, this isn't necessary and
less efficient than just using O_NOFOLLOW.  So can't this test be made
conditional for systems lacking O_NOFOLLOW?

Miklos