Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.37 as permitted sender) client-ip=23.128.96.37;
Date:   Mon, 16 Oct 2023 22:35:59 +0200
From:   Ahelenia =?utf-8?Q?Ziemia=C5=84ska?= 
        <nabijaczleweli@nabijaczleweli.xyz>
Cc:     Alexander Viro <viro@zeniv.linux.org.uk>,
        Christian Brauner <brauner@kernel.org>,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 10/11] splice: file->pipe: -EINVAL for non-regular files w/o
 FMODE_NOWAIT
Message-ID: <5974c79b84c0b3aad566ff7c33b082f90ac5f17e.1697486714.git.nabijaczleweli@nabijaczleweli.xyz>
References: <cover.1697486714.git.nabijaczleweli@nabijaczleweli.xyz>
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha512;
        protocol="application/pgp-signature"; boundary="2kmqog55wiriurlb"
Content-Disposition: inline
In-Reply-To: <cover.1697486714.git.nabijaczleweli@nabijaczleweli.xyz>
User-Agent: NeoMutt/20231006
To:     unlisted-recipients:; (no To-header on input)
Precedence: bulk


--2kmqog55wiriurlb
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

We request non-blocking I/O in the generic implementation, but some
files =E2=80=92 ttys =E2=80=92 only check O_NONBLOCK. Refuse them here, les=
t we
risk sleeping with the pipe locked for indeterminate lengths of
time.

This also masks inconsistent wake-ups (usually every second line)
when splicing from ttys in icanon mode.

Regular files don't /have/ a distinct O_NONBLOCK mode,
because they always behave non-blockingly, and for them FMODE_NOWAIT is
used in the purest sense of
  /* File is capable of returning -EAGAIN if I/O will block */
which is not set by the vast majority of filesystems,
and it's not the semantic we want here.

Link: https://lore.kernel.org/linux-fsdevel/qk6hjuam54khlaikf2ssom6custxf5i=
s2ekkaequf4hvode3ls@zgf7j5j4ubvw/t/#u
Signed-off-by: Ahelenia Ziemia=C5=84ska <nabijaczleweli@nabijaczleweli.xyz>
---
 fs/splice.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/splice.c b/fs/splice.c
index 9d29664f23ee..81788bf7daa1 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -1300,6 +1300,8 @@ long do_splice(struct file *in, loff_t *off_in, struc=
t file *out,
 	} else if (opipe) {
 		if (off_out)
 			return -ESPIPE;
+		if (!((in->f_mode & FMODE_NOWAIT) || S_ISREG(in->f_inode->i_mode)))
+			return -EINVAL;
 		if (off_in) {
 			if (!(in->f_mode & FMODE_PREAD))
 				return -EINVAL;
--=20
2.39.2

--2kmqog55wiriurlb
Content-Type: application/pgp-signature; name="signature.asc"

-----BEGIN PGP SIGNATURE-----
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=39/H
-----END PGP SIGNATURE-----

--2kmqog55wiriurlb--