linux-kernel - [PATCH v2 1/2] open: make RESOLVE_CACHED correctly test for O

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Message-Id: <20230806-resolve_cached-o_tmpfile-v2-1-058bff24fb16@cyphar.com>
Date:   Sun, 06 Aug 2023 08:48:08 +1000
From:   Aleksa Sarai <cyphar@...har.com>
To:     Alexander Viro <viro@...iv.linux.org.uk>,
        Christian Brauner <brauner@...nel.org>,
        Jens Axboe <axboe@...nel.dk>,
        Pavel Begunkov <asml.silence@...il.com>
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        io-uring@...r.kernel.org, Aleksa Sarai <cyphar@...har.com>,
        stable@...r.kernel.org
Subject: [PATCH v2 1/2] open: make RESOLVE_CACHED correctly test for
 O_TMPFILE

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@...r.kernel.org # v5.12+
Fixes: 99668f618062 ("fs: expose LOOKUP_CACHED through openat2() RESOLVE_CACHED")
Signed-off-by: Aleksa Sarai <cyphar@...har.com>
---
 fs/open.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/open.c b/fs/open.c
index b8883ec286f5..2634047c9e9f 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -1337,7 +1337,7 @@ 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;
 	}

-- 
2.41.0