Re: Have RESOLVE_* flags superseded AT_* flags for new syscalls?

David Howells
2020-03-02T15:23:33Z

Aleksa Sarai <cyphar@cyphar.com> wrote:

> My counter-argument is that most people actually want
> RESOLVE_NO_SYMLINKS (as evidenced by the countless symlink-related
> security bugs -- many of which used O_NOFOLLOW incorrectly), it just
> wasn't available before Linux 5.6.

I would quibble as to whether they actually want this in all situations.
There are some in which the difference in behaviour will conceivably break
things - though that's more the case for things like stat(), statx(), fsinfo()
and getxattr() where you might want to be able to query a specific symlink
than for openat2() where you almost always want to follow it (save O_PATH |
O_NOFOLLOW).

However, if you're okay with me adding, say, RESOLVE_NO_TERMINAL_SYMLINK and
RESOLVE_NO_TERMINAL_AUTOMOUNT, I can use these flags.

I don't want to have to allow both RESOLVE_* and AT_*.

David