open: make RESOLVE_CACHED correctly test for O_TMPFILE

BugLink: https://bugs.launchpad.net/bugs/2038236

commit a0fc452 upstream.

O_TMPFILE is actually __O_TMPFILE|O_DIRECTORY. This means that the old
fast-path check for RESOLVE_CACHED would reject all users passing
O_DIRECTORY with -EAGAIN, when in fact the intended test was to check
for __O_TMPFILE.

Cc: stable@vger.kernel.org # v5.12+
Fixes: 99668f6 ("fs: expose LOOKUP_CACHED through openat2() RESOLVE_CACHED")
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
Message-Id: <20230806-resolve_cached-o_tmpfile-v1-1-7ba16308465e@cyphar.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

Author: cyphar

fs/open.c

@@ -1233,7 +1233,7 @@ inline int build_open_flags(const struct open_how *how, struct open_flags *op)
 		lookup_flags |= LOOKUP_IN_ROOT;
 	if (how->resolve & RESOLVE_CACHED) {
 		/* Don't bother even trying for create/truncate/tmpfile open */
-		if (flags & (O_TRUNC | O_CREAT | O_TMPFILE))
+		if (flags & (O_TRUNC | O_CREAT | __O_TMPFILE))
 			return -EAGAIN;
 		lookup_flags |= LOOKUP_CACHED;
 	}