From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5FF3C2F0C7F; Tue, 27 Jan 2026 23:52:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769557927; cv=none; b=GFQa5tcqkmqKEfzkEIJZodI3FZihles196sqZvAEpBfM3H7CFwlv+Tf0XsjIAQPSTfu4SdcDRQwg2Ma7Q/sGgaJNnujgnyrlS9WzA95usxWAlQkr9opRYvauiZAHhg9CUQfTa5cJletXZ3zFuiGIpL2d4nlQ6PO2uWwxysbgj4Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769557927; c=relaxed/simple; bh=ecpQGcQgr6cpdg2+5kNqtT0FxNBT/0Ch1ZMdCpv0Opo=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=ZCPMqZCBaArTNI8DCYdHAMOFZ+shMifMi+Lax9HZdxkpPij82ufeHdsTANhYrQtq+y06v7p6yfDZeE+eIRsdLBg//2G/XkIbJ14bF6xjToki1p6uPPr2Z7O966gkA6RumSPEfbMYrWISSp7jg/7NI90Kh37RfUtd1aDmrZQyRTU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JcYkahdi; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="JcYkahdi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F2632C19422; Tue, 27 Jan 2026 23:52:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1769557927; bh=ecpQGcQgr6cpdg2+5kNqtT0FxNBT/0Ch1ZMdCpv0Opo=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=JcYkahdiEW7BY4pMtQ9/U9hn4f2p+ZROsorNTamoB9Vy/CsPWciR9+KYld49a9mmI fQG3f6SH22zWVj3+98dPDN8YIr+SkrktPFwO/jbhZF9olPLenaKYzJ6yF4lP3udIoR +3kuAm8R5V04nKYUBcPPqyG8TKwPLDMe8GChAviTueYqTwz3I+BOJ83PQEF/9OlALB CW6fw/nGfubiZWmGP2MiHxjOiv0YJCXRYXZ11GxyU7ADukbeQaTZ1zLdJ9WDjx5jOX 4nWvyWJoR8JDEhbkSr9YzHcOBW2FLJeWX1b80d7GVAsJC9d3RDUZoa5itWpmJ5XUrQ dMzwFs+pWbfhg== Message-ID: <1c6cccc3e058ef16fa8b296ef6126b76a12db136.camel@kernel.org> Subject: Re: [PATCH v3 1/4] open: new O_REGULAR flag support From: Jeff Layton To: Dorjoy Chowdhury , linux-fsdevel@vger.kernel.org Cc: linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk, brauner@kernel.org, jack@suse.cz, chuck.lever@oracle.com, alex.aring@gmail.com, arnd@arndb.de, adilger@dilger.ca Date: Tue, 27 Jan 2026 18:52:04 -0500 In-Reply-To: <20260127180109.66691-2-dorjoychy111@gmail.com> References: <20260127180109.66691-1-dorjoychy111@gmail.com> <20260127180109.66691-2-dorjoychy111@gmail.com> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv 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linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Tue, 2026-01-27 at 23:58 +0600, Dorjoy Chowdhury wrote: > This flag indicates the path should be opened if it's a regular file. > This is useful to write secure programs that want to avoid being tricked > into opening device nodes with special semantics while thinking they > operate on regular files. >=20 > A corresponding error code ENOTREG has been introduced. For example, if > open is called on path /dev/null with O_REGULAR in the flag param, it > will return -ENOTREG. >=20 > When used in combination with O_CREAT, either the regular file is > created, or if the path already exists, it is opened if it's a regular > file. Otherwise, -ENOTREG is returned. >=20 > -EINVAL is returned when O_REGULAR is combined with O_DIRECTORY (not > part of O_TMPFILE) because it doesn't make sense to open a path that > is both a directory and a regular file. >=20 > Signed-off-by: Dorjoy Chowdhury > --- > arch/alpha/include/uapi/asm/errno.h | 2 ++ > arch/alpha/include/uapi/asm/fcntl.h | 1 + > arch/mips/include/uapi/asm/errno.h | 2 ++ > arch/parisc/include/uapi/asm/errno.h | 2 ++ > arch/parisc/include/uapi/asm/fcntl.h | 1 + > arch/sparc/include/uapi/asm/errno.h | 2 ++ > arch/sparc/include/uapi/asm/fcntl.h | 1 + > fs/fcntl.c | 2 +- > fs/namei.c | 6 ++++++ > fs/open.c | 4 +++- > include/linux/fcntl.h | 2 +- > include/uapi/asm-generic/errno.h | 2 ++ > include/uapi/asm-generic/fcntl.h | 4 ++++ > tools/arch/alpha/include/uapi/asm/errno.h | 2 ++ > tools/arch/mips/include/uapi/asm/errno.h | 2 ++ > tools/arch/parisc/include/uapi/asm/errno.h | 2 ++ > tools/arch/sparc/include/uapi/asm/errno.h | 2 ++ > tools/include/uapi/asm-generic/errno.h | 2 ++ > 18 files changed, 38 insertions(+), 3 deletions(-) >=20 > diff --git a/arch/alpha/include/uapi/asm/errno.h b/arch/alpha/include/uap= i/asm/errno.h > index 6791f6508632..8bbcaa9024f9 100644 > --- a/arch/alpha/include/uapi/asm/errno.h > +++ b/arch/alpha/include/uapi/asm/errno.h > @@ -127,4 +127,6 @@ > =20 > #define EHWPOISON 139 /* Memory page has hardware error */ > =20 > +#define ENOTREG 140 /* Not a regular file */ > + > #endif > diff --git a/arch/alpha/include/uapi/asm/fcntl.h b/arch/alpha/include/uap= i/asm/fcntl.h > index 50bdc8e8a271..4da5a64c23bd 100644 > --- a/arch/alpha/include/uapi/asm/fcntl.h > +++ b/arch/alpha/include/uapi/asm/fcntl.h > @@ -34,6 +34,7 @@ > =20 > #define O_PATH 040000000 > #define __O_TMPFILE 0100000000 > +#define O_REGULAR 0200000000 > =20 > #define F_GETLK 7 > #define F_SETLK 8 > diff --git a/arch/mips/include/uapi/asm/errno.h b/arch/mips/include/uapi/= asm/errno.h > index c01ed91b1ef4..293c78777254 100644 > --- a/arch/mips/include/uapi/asm/errno.h > +++ b/arch/mips/include/uapi/asm/errno.h > @@ -126,6 +126,8 @@ > =20 > #define EHWPOISON 168 /* Memory page has hardware error */ > =20 > +#define ENOTREG 169 /* Not a regular file */ > + > #define EDQUOT 1133 /* Quota exceeded */ > =20 > =20 > diff --git a/arch/parisc/include/uapi/asm/errno.h b/arch/parisc/include/u= api/asm/errno.h > index 8cbc07c1903e..442917484f99 100644 > --- a/arch/parisc/include/uapi/asm/errno.h > +++ b/arch/parisc/include/uapi/asm/errno.h > @@ -124,4 +124,6 @@ > =20 > #define EHWPOISON 257 /* Memory page has hardware error */ > =20 > +#define ENOTREG 258 /* Not a regular file */ > + > #endif > diff --git a/arch/parisc/include/uapi/asm/fcntl.h b/arch/parisc/include/u= api/asm/fcntl.h > index 03dee816cb13..0cc3320fe326 100644 > --- a/arch/parisc/include/uapi/asm/fcntl.h > +++ b/arch/parisc/include/uapi/asm/fcntl.h > @@ -19,6 +19,7 @@ > =20 > #define O_PATH 020000000 > #define __O_TMPFILE 040000000 > +#define O_REGULAR 0100000000 > =20 > #define F_GETLK64 8 > #define F_SETLK64 9 > diff --git a/arch/sparc/include/uapi/asm/errno.h b/arch/sparc/include/uap= i/asm/errno.h > index 4a41e7835fd5..8dce0bfeab74 100644 > --- a/arch/sparc/include/uapi/asm/errno.h > +++ b/arch/sparc/include/uapi/asm/errno.h > @@ -117,4 +117,6 @@ > =20 > #define EHWPOISON 135 /* Memory page has hardware error */ > =20 > +#define ENOTREG 136 /* Not a regular file */ > + > #endif > diff --git a/arch/sparc/include/uapi/asm/fcntl.h b/arch/sparc/include/uap= i/asm/fcntl.h > index 67dae75e5274..a93d18d2c23e 100644 > --- a/arch/sparc/include/uapi/asm/fcntl.h > +++ b/arch/sparc/include/uapi/asm/fcntl.h > @@ -37,6 +37,7 @@ > =20 > #define O_PATH 0x1000000 > #define __O_TMPFILE 0x2000000 > +#define O_REGULAR 0x4000000 > =20 > #define F_GETOWN 5 /* for sockets. */ > #define F_SETOWN 6 /* for sockets. */ > diff --git a/fs/fcntl.c b/fs/fcntl.c > index f93dbca08435..62ab4ad2b6f5 100644 > --- a/fs/fcntl.c > +++ b/fs/fcntl.c > @@ -1169,7 +1169,7 @@ static int __init fcntl_init(void) > * Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY > * is defined as O_NONBLOCK on some platforms and not on others. > */ > - BUILD_BUG_ON(20 - 1 /* for O_RDONLY being 0 */ !=3D > + BUILD_BUG_ON(21 - 1 /* for O_RDONLY being 0 */ !=3D > HWEIGHT32( > (VALID_OPEN_FLAGS & ~(O_NONBLOCK | O_NDELAY)) | > __FMODE_EXEC)); > diff --git a/fs/namei.c b/fs/namei.c > index b28ecb699f32..f5504ae4b03c 100644 > --- a/fs/namei.c > +++ b/fs/namei.c > @@ -4616,6 +4616,10 @@ static int do_open(struct nameidata *nd, > if (unlikely(error)) > return error; > } > + > + if ((open_flag & O_REGULAR) && !d_is_reg(nd->path.dentry)) > + return -ENOTREG; > + > if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) > return -ENOTDIR; > =20 > @@ -4765,6 +4769,8 @@ static int do_o_path(struct nameidata *nd, unsigned= flags, struct file *file) > struct path path; > int error =3D path_lookupat(nd, flags, &path); > if (!error) { > + if ((file->f_flags & O_REGULAR) && !d_is_reg(path.dentry)) > + return -ENOTREG; > audit_inode(nd->name, path.dentry, 0); > error =3D vfs_open(&path, file); > path_put(&path); > diff --git a/fs/open.c b/fs/open.c > index 74c4c1462b3e..82153e21907e 100644 > --- a/fs/open.c > +++ b/fs/open.c > @@ -1173,7 +1173,7 @@ struct file *kernel_file_open(const struct path *pa= th, int flags, > EXPORT_SYMBOL_GPL(kernel_file_open); > =20 > #define WILL_CREATE(flags) (flags & (O_CREAT | __O_TMPFILE)) > -#define O_PATH_FLAGS (O_DIRECTORY | O_NOFOLLOW | O_PATH | O_CLOEXEC) > +#define O_PATH_FLAGS (O_DIRECTORY | O_NOFOLLOW | O_PATH | O_CLOEXEC | O= _REGULAR) > =20 > inline struct open_how build_open_how(int flags, umode_t mode) > { > @@ -1250,6 +1250,8 @@ inline int build_open_flags(const struct open_how *= how, struct open_flags *op) > return -EINVAL; > if (!(acc_mode & MAY_WRITE)) > return -EINVAL; > + } else if ((flags & O_DIRECTORY) && (flags & O_REGULAR)) { > + return -EINVAL; > } > if (flags & O_PATH) { > /* O_PATH only permits certain other flags to be set. */ > diff --git a/include/linux/fcntl.h b/include/linux/fcntl.h > index a332e79b3207..4fd07b0e0a17 100644 > --- a/include/linux/fcntl.h > +++ b/include/linux/fcntl.h > @@ -10,7 +10,7 @@ > (O_RDONLY | O_WRONLY | O_RDWR | O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC |= \ > O_APPEND | O_NDELAY | O_NONBLOCK | __O_SYNC | O_DSYNC | \ > FASYNC | O_DIRECT | O_LARGEFILE | O_DIRECTORY | O_NOFOLLOW | \ > - O_NOATIME | O_CLOEXEC | O_PATH | __O_TMPFILE) > + O_NOATIME | O_CLOEXEC | O_PATH | __O_TMPFILE | O_REGULAR) > =20 > /* List of all valid flags for the how->resolve argument: */ > #define VALID_RESOLVE_FLAGS \ > diff --git a/include/uapi/asm-generic/errno.h b/include/uapi/asm-generic/= errno.h > index 92e7ae493ee3..2216ab9aa32e 100644 > --- a/include/uapi/asm-generic/errno.h > +++ b/include/uapi/asm-generic/errno.h > @@ -122,4 +122,6 @@ > =20 > #define EHWPOISON 133 /* Memory page has hardware error */ > =20 > +#define ENOTREG 134 /* Not a regular file */ > + > #endif > diff --git a/include/uapi/asm-generic/fcntl.h b/include/uapi/asm-generic/= fcntl.h > index 613475285643..3468b352a575 100644 > --- a/include/uapi/asm-generic/fcntl.h > +++ b/include/uapi/asm-generic/fcntl.h > @@ -88,6 +88,10 @@ > #define __O_TMPFILE 020000000 > #endif > =20 > +#ifndef O_REGULAR > +#define O_REGULAR 040000000 > +#endif > + > /* a horrid kludge trying to make sure that this will fail on old kernel= s */ > #define O_TMPFILE (__O_TMPFILE | O_DIRECTORY) > =20 > diff --git a/tools/arch/alpha/include/uapi/asm/errno.h b/tools/arch/alpha= /include/uapi/asm/errno.h > index 6791f6508632..8bbcaa9024f9 100644 > --- a/tools/arch/alpha/include/uapi/asm/errno.h > +++ b/tools/arch/alpha/include/uapi/asm/errno.h > @@ -127,4 +127,6 @@ > =20 > #define EHWPOISON 139 /* Memory page has hardware error */ > =20 > +#define ENOTREG 140 /* Not a regular file */ > + > #endif > diff --git a/tools/arch/mips/include/uapi/asm/errno.h b/tools/arch/mips/i= nclude/uapi/asm/errno.h > index c01ed91b1ef4..293c78777254 100644 > --- a/tools/arch/mips/include/uapi/asm/errno.h > +++ b/tools/arch/mips/include/uapi/asm/errno.h > @@ -126,6 +126,8 @@ > =20 > #define EHWPOISON 168 /* Memory page has hardware error */ > =20 > +#define ENOTREG 169 /* Not a regular file */ > + > #define EDQUOT 1133 /* Quota exceeded */ > =20 > =20 > diff --git a/tools/arch/parisc/include/uapi/asm/errno.h b/tools/arch/pari= sc/include/uapi/asm/errno.h > index 8cbc07c1903e..442917484f99 100644 > --- a/tools/arch/parisc/include/uapi/asm/errno.h > +++ b/tools/arch/parisc/include/uapi/asm/errno.h > @@ -124,4 +124,6 @@ > =20 > #define EHWPOISON 257 /* Memory page has hardware error */ > =20 > +#define ENOTREG 258 /* Not a regular file */ > + > #endif > diff --git a/tools/arch/sparc/include/uapi/asm/errno.h b/tools/arch/sparc= /include/uapi/asm/errno.h > index 4a41e7835fd5..8dce0bfeab74 100644 > --- a/tools/arch/sparc/include/uapi/asm/errno.h > +++ b/tools/arch/sparc/include/uapi/asm/errno.h > @@ -117,4 +117,6 @@ > =20 > #define EHWPOISON 135 /* Memory page has hardware error */ > =20 > +#define ENOTREG 136 /* Not a regular file */ > + > #endif > diff --git a/tools/include/uapi/asm-generic/errno.h b/tools/include/uapi/= asm-generic/errno.h > index 92e7ae493ee3..2216ab9aa32e 100644 > --- a/tools/include/uapi/asm-generic/errno.h > +++ b/tools/include/uapi/asm-generic/errno.h > @@ -122,4 +122,6 @@ > =20 > #define EHWPOISON 133 /* Memory page has hardware error */ > =20 > +#define ENOTREG 134 /* Not a regular file */ > + > #endif One thing this patch is missing is handling for ->atomic_open(). I imagine most of the filesystems that provide that op can't support O_REGULAR properly (maybe cifs can? idk). What you probably want to do is add in some patches that make all of the atomic_open operations in the kernel return -EINVAL if O_REGULAR is set. Then, once the basic support is in, you or someone else can go back and implement support for O_REGULAR where possible. --=20 Jeff Layton