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 2982823907E; Mon, 7 Apr 2025 12:19:27 +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=1744028368; cv=none; b=F9qwvkhbTgX3CcVpvmmCaVNnEUpTXcrWD2OgIEpXS18FT4Ds06RTsISvoa1XZnWKiTJ11hX9AnEltV6IsstHcpfxIo59Va5buh6MMbW47K2NRpZq9uiVfTu270YEhKgm7fKz63cRmOWm1AoY64VkGCaEKPvyA77JxnXGzT4Oq50= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744028368; c=relaxed/simple; bh=9/e70p2LL1FnQygMmOhD5HM46aVyjlYEtUpR4XAuHg0=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=iaokqdCpvL9LN8ln04qaFYzhvIxTWqsXoEcpmCV50WK4gFglO8wPnDyw56qY7AJERV6TnZZXms4ePDB/PiIK0KcPtW3ggA0HG5obgnSIIc0LQEQwAtVAukOvKdGZkoXSBYJhdeE55lo3ms04OrADDAxNE8NgVFEdtXScGqjtOOM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=LrzmbwZI; 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="LrzmbwZI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D2269C4CEDD; Mon, 7 Apr 2025 12:19:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1744028367; bh=9/e70p2LL1FnQygMmOhD5HM46aVyjlYEtUpR4XAuHg0=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=LrzmbwZIbHW+LpTXis6xG3QjqVHe5CLKock553NEfcL24noNZ6PuuF+UcawcNFQY/ yuUm1NvPlwAJxeFHEWMLWtwzJ7hDlDvs6PDWud6AtB3mmK8pW//3kSUCReN2l34ojS pIVEUngbAXAdaHoYjkX3T/XuQtXBq78+o4L1C8g6p1KguE5hNVWKhw6nPlXNmxvYRl wqmr5oo/Rxra/UTc1r0hm6F+dS/+8bM8A2WS8GHsudECoUW05wFTJIYCDjPgOKhsA/ s2luLv/btOGVOHxA1jfhvusAEbIpx1GF8wINvOza8kQkQNfAmYgDWtcOQCQrSpzSdK 94ktqmzTq/hMA== Message-ID: Subject: Re: [PATCH 1/9] anon_inode: use a proper mode internally From: Jeff Layton To: Christian Brauner , linux-fsdevel@vger.kernel.org Cc: Christoph Hellwig , Mateusz Guzik , Penglei Jiang , Al Viro , Jan Kara , Josef Bacik , syzbot+5d8e79d323a13aa0b248@syzkaller.appspotmail.com, stable@vger.kernel.org Date: Mon, 07 Apr 2025 08:19:25 -0400 In-Reply-To: <20250407-work-anon_inode-v1-1-53a44c20d44e@kernel.org> References: <20250407-work-anon_inode-v1-0-53a44c20d44e@kernel.org> <20250407-work-anon_inode-v1-1-53a44c20d44e@kernel.org> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV 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Mon, 2025-04-07 at 11:54 +0200, Christian Brauner wrote: > This allows the VFS to not trip over anonymous inodes and we can add > asserts based on the mode into the vfs. When we report it to userspace > we can simply hide the mode to avoid regressions. I've audited all > direct callers of alloc_anon_inode() and only secretmen overrides i_mode > and i_op inode operations but it already uses a regular file. >=20 > Fixes: af153bb63a336 ("vfs: catch invalid modes in may_open()") > Cc: # all LTS kernels > Reported-by: syzbot+5d8e79d323a13aa0b248@syzkaller.appspotmail.com > Closes: https://lore.kernel.org/all/67ed3fb3.050a0220.14623d.0009.GAE@goo= gle.com > Signed-off-by: Christian Brauner > --- > fs/anon_inodes.c | 36 ++++++++++++++++++++++++++++++++++++ > fs/internal.h | 3 +++ > fs/libfs.c | 2 +- > 3 files changed, 40 insertions(+), 1 deletion(-) >=20 > diff --git a/fs/anon_inodes.c b/fs/anon_inodes.c > index 583ac81669c2..42e4b9c34f89 100644 > --- a/fs/anon_inodes.c > +++ b/fs/anon_inodes.c > @@ -24,9 +24,43 @@ > =20 > #include > =20 > +#include "internal.h" > + > static struct vfsmount *anon_inode_mnt __ro_after_init; > static struct inode *anon_inode_inode __ro_after_init; > =20 > +/* > + * User space expects anonymous inodes to have no file type in st_mode. Weird. Does anything actually depend on this? ISTM that they should report a file type. > + * > + * In particular, 'lsof' has this legacy logic: > + * > + * type =3D s->st_mode & S_IFMT; > + * switch (type) { > + * ... > + * case 0: > + * if (!strcmp(p, "anon_inode")) > + * Lf->ntype =3D Ntype =3D N_ANON_INODE; > + * > + * to detect our old anon_inode logic. > + * > + * Rather than mess with our internal sane inode data, just fix it > + * up here in getattr() by masking off the format bits. > + */ > +int anon_inode_getattr(struct mnt_idmap *idmap, const struct path *path, > + struct kstat *stat, u32 request_mask, > + unsigned int query_flags) > +{ > + struct inode *inode =3D d_inode(path->dentry); > + > + generic_fillattr(&nop_mnt_idmap, request_mask, inode, stat); > + stat->mode &=3D ~S_IFMT; > + return 0; > +} > + > +static const struct inode_operations anon_inode_operations =3D { > + .getattr =3D anon_inode_getattr, > +}; > + > /* > * anon_inodefs_dname() is called from d_path(). > */ > @@ -66,6 +100,7 @@ static struct inode *anon_inode_make_secure_inode( > if (IS_ERR(inode)) > return inode; > inode->i_flags &=3D ~S_PRIVATE; > + inode->i_op =3D &anon_inode_operations; > error =3D security_inode_init_security_anon(inode, &QSTR(name), > context_inode); > if (error) { > @@ -313,6 +348,7 @@ static int __init anon_inode_init(void) > anon_inode_inode =3D alloc_anon_inode(anon_inode_mnt->mnt_sb); > if (IS_ERR(anon_inode_inode)) > panic("anon_inode_init() inode allocation failed (%ld)\n", PTR_ERR(ano= n_inode_inode)); > + anon_inode_inode->i_op =3D &anon_inode_operations; > =20 > return 0; > } > diff --git a/fs/internal.h b/fs/internal.h > index b9b3e29a73fd..717dc9eb6185 100644 > --- a/fs/internal.h > +++ b/fs/internal.h > @@ -343,3 +343,6 @@ static inline bool path_mounted(const struct path *pa= th) > void file_f_owner_release(struct file *file); > bool file_seek_cur_needs_f_lock(struct file *file); > int statmount_mnt_idmap(struct mnt_idmap *idmap, struct seq_file *seq, b= ool uid_map); > +int anon_inode_getattr(struct mnt_idmap *idmap, const struct path *path, > + struct kstat *stat, u32 request_mask, > + unsigned int query_flags); > diff --git a/fs/libfs.c b/fs/libfs.c > index 6393d7c49ee6..0ad3336f5b49 100644 > --- a/fs/libfs.c > +++ b/fs/libfs.c > @@ -1647,7 +1647,7 @@ struct inode *alloc_anon_inode(struct super_block *= s) > * that it already _is_ on the dirty list. > */ > inode->i_state =3D I_DIRTY; > - inode->i_mode =3D S_IRUSR | S_IWUSR; > + inode->i_mode =3D S_IFREG | S_IRUSR | S_IWUSR; > inode->i_uid =3D current_fsuid(); > inode->i_gid =3D current_fsgid(); > inode->i_flags |=3D S_PRIVATE; >=20 --=20 Jeff Layton