From nobody Sun Feb 8 16:32:03 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 92FD2EB64DA for ; Sat, 24 Jun 2023 23:10:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230088AbjFXXKQ (ORCPT ); Sat, 24 Jun 2023 19:10:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47894 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229882AbjFXXKD (ORCPT ); Sat, 24 Jun 2023 19:10:03 -0400 Received: from wout1-smtp.messagingengine.com (wout1-smtp.messagingengine.com [64.147.123.24]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A7D3B1715 for ; Sat, 24 Jun 2023 16:10:02 -0700 (PDT) Received: from compute2.internal (compute2.nyi.internal [10.202.2.46]) by mailout.west.internal (Postfix) with ESMTP id DF02D32004AE; Sat, 24 Jun 2023 19:10:01 -0400 (EDT) Received: from mailfrontend1 ([10.202.2.162]) by compute2.internal (MEProxy); Sat, 24 Jun 2023 19:10:02 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= invisiblethingslab.com; h=cc:cc:content-transfer-encoding :content-type:date:date:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:sender:subject :subject:to:to; s=fm2; t=1687648201; x=1687734601; bh=dxRbzU1iZA ZEi/0QoA6KMOWrU2r13cVV3OFozBagpS0=; b=ZeexDdSUuI5IHYYFhrXNZxn7a2 B+aCTDQ7OMT6GD3MIDKy17AOzomwaIujUl+Vx5khkgDD2BoC5DMRE/LoPjb0aaSt hhwbsC9MAI569TFtX+wlJr4mNFT42SELZHdwLxHs7mEq2iZ/WSVbMLe3eWruvG1b 2+mj3NHK39YlGFBen4kXwPgjCn9TcAwYNPMyDc46sxYApDDuWpPn/MyFjBuArHbO 9FDKFqAP7U8TBuglqMzzq3GQZKZHqzL+lhVTLSiPvkN0/yQHn8fExGNB9pziTluG 2bosoCbXRrYUtW8rqWguxNwVblAdyb44RB878hytsxegleVzQJTeY3cO0BPw== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-transfer-encoding :content-type:date:date:feedback-id:feedback-id:from:from :in-reply-to:in-reply-to:message-id:mime-version:references :reply-to:sender:subject:subject:to:to:x-me-proxy:x-me-proxy :x-me-sender:x-me-sender:x-sasl-enc; s=fm2; t=1687648201; x= 1687734601; bh=dxRbzU1iZAZEi/0QoA6KMOWrU2r13cVV3OFozBagpS0=; b=j d5Lwt0CJn4Mh8nWni6Q1NbN1muziTQf36uinjpOPOOBHCu/GagkQksdaz9iyoCCu ThhaLBHxJ0wnk22Grm+6eTpfXQK5Z87NlKsc0K9INhQWjWM/ZwFbDlYLZez0E9R6 az0TqgFEgpiqJL6IqYXrZleU4HLAiCI50aYchs5nQq6x39oJRRDNHbmvIwtmX5fR X4To/t1pWXa+Xz503Z6eN4m0khkP8wr3KS5LiGyvel85SMp0mKVUOalfRqHG5cvW cNY3B2DlL6m65b7ptZ443WTje6EMKKUCUMn835oHgIQAPAUvGKLypkNvupqRQGxa MrkO/9Bz0NGKka0tBJyKg== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvhedrgeegkedgudekucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhephffvvefufffkofgjfhgggfestdekredtredttdenucfhrhhomhepffgvmhhi ucforghrihgvucfqsggvnhhouhhruceouggvmhhisehinhhvihhsihgslhgvthhhihhngh hslhgrsgdrtghomheqnecuggftrfgrthhtvghrnhepjeffjefggfeugeduvedvjeekgfeh gffhhfffjeetkeelueefffetfffhtdduheetnecuvehluhhsthgvrhfuihiivgeptdenuc frrghrrghmpehmrghilhhfrhhomhepuggvmhhisehinhhvihhsihgslhgvthhhihhnghhs lhgrsgdrtghomh X-ME-Proxy: Feedback-ID: iac594737:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Sat, 24 Jun 2023 19:10:00 -0400 (EDT) From: Demi Marie Obenour To: Alasdair Kergon , Mike Snitzer , dm-devel@redhat.com Cc: Demi Marie Obenour , linux-kernel@vger.kernel.org Subject: [PATCH v2 2/4] dm ioctl: Allow userspace to provide expected diskseq Date: Sat, 24 Jun 2023 19:09:45 -0400 Message-ID: <20230624230950.2272-3-demi@invisiblethingslab.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230624230950.2272-1-demi@invisiblethingslab.com> References: <20230624230950.2272-1-demi@invisiblethingslab.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" This can be used to avoid race conditions in which a device is destroyed and recreated with the same major/minor, name, or UUID. diskseqs are only honored if strict parameter checking is on, to avoid any risk of breaking old userspace. Signed-off-by: Demi Marie Obenour --- drivers/md/dm-ioctl.c | 41 +++++++++++++++++++++++++++++------ include/uapi/linux/dm-ioctl.h | 31 ++++++++++++++++++++++++-- 2 files changed, 63 insertions(+), 9 deletions(-) diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c index e7693479c0cd974ddde69b3b1c4c67abc2ae3ad6..7abaeec33f1884d4588e8563fb0= 2e9ea1a6782c8 100644 --- a/drivers/md/dm-ioctl.c +++ b/drivers/md/dm-ioctl.c @@ -878,6 +878,9 @@ static void __dev_status(struct mapped_device *md, stru= ct dm_ioctl *param) } dm_put_live_table(md, srcu_idx); } + + if (param->version[0] >=3D DM_VERSION_MAJOR_STRICT) + dm_set_diskseq(param, disk->diskseq); } =20 static int dev_create(struct file *filp, struct dm_ioctl *param, size_t pa= ram_size) @@ -918,6 +921,9 @@ static int dev_create(struct file *filp, struct dm_ioct= l *param, size_t param_si static struct hash_cell *__find_device_hash_cell(struct dm_ioctl *param) { struct hash_cell *hc =3D NULL; + static_assert(offsetof(struct dm_ioctl, diskseq_high) =3D=3D + offsetof(struct dm_ioctl, data) + 3, + "diskseq_high field misplaced"); =20 if (*param->uuid) { if (*param->name || param->dev) { @@ -946,6 +952,27 @@ static struct hash_cell *__find_device_hash_cell(struc= t dm_ioctl *param) } else return NULL; =20 + if (param->version[0] >=3D DM_VERSION_MAJOR_STRICT) { + u64 expected_diskseq =3D dm_get_diskseq(param); + u64 diskseq; + struct mapped_device *md =3D hc->md; + + if (WARN_ON_ONCE(md->disk =3D=3D NULL)) + return NULL; + diskseq =3D md->disk->diskseq; + if (WARN_ON_ONCE(diskseq =3D=3D 0)) + return NULL; + if (expected_diskseq !=3D 0) { + if (expected_diskseq !=3D diskseq) { + DMERR("Diskseq mismatch: expected %llu actual %llu", + expected_diskseq, diskseq); + return NULL; + } + } else { + dm_set_diskseq(param, diskseq); + } + } + /* * Sneakily write in both the name and the uuid * while we have the cell. @@ -2139,6 +2166,12 @@ static int validate_params(uint cmd, struct dm_ioctl= *param, return 0; } =20 + if (param->data_size < sizeof(struct dm_ioctl)) { + DMERR("Entire struct dm_ioctl (size %zu) must be valid, but only %u was = valid", + sizeof(struct dm_ioctl), param->data_size); + return -EINVAL; + } + /* Check that strings are terminated */ if (!no_non_nul_after_nul(param->name, DM_NAME_LEN, cmd, "Name") || !no_non_nul_after_nul(param->uuid, DM_UUID_LEN, cmd, "UUID")) @@ -2148,7 +2181,7 @@ static int validate_params(uint cmd, struct dm_ioctl = *param, * This also checks the last byte of the UUID field, but that was * checked to be zero above. */ - if (*(const u64 *)((const char *)param + (sizeof(*param) - 8)) !=3D 0) { + if (*(const u32 *)((const char *)param + (sizeof(*param) - 8)) !=3D 0) { DMERR("second padding field not zeroed in strict mode (cmd %u)", cmd); return -EINVAL; } @@ -2159,12 +2192,6 @@ static int validate_params(uint cmd, struct dm_ioctl= *param, return -EINVAL; } =20 - if (param->padding !=3D 0) { - DMERR("padding not zeroed in strict mode (got %u, cmd %u)", - param->padding, cmd); - return -EINVAL; - } - if (param->open_count !=3D 0) { DMERR("open_count not zeroed in strict mode (got %d, cmd %u)", param->open_count, cmd); diff --git a/include/uapi/linux/dm-ioctl.h b/include/uapi/linux/dm-ioctl.h index 62bfdc95ebccb2f1c20c24496a449fe3e2a76113..1d33109aece2ff9854e752066ba= a96fdf7d85857 100644 --- a/include/uapi/linux/dm-ioctl.h +++ b/include/uapi/linux/dm-ioctl.h @@ -146,16 +146,43 @@ struct dm_ioctl { * For output, the ioctls return the event number, not the cookie. */ __u32 event_nr; /* in/out */ - __u32 padding; + + union { + /* valid if DM_VERSION_MAJOR is used */ + __u32 padding; /* padding */ + /* valid if DM_VERSION_MAJOR_STRICT is used */ + __u32 diskseq_low; /* in/out: low 4 bytes of the diskseq */ + }; =20 __u64 dev; /* in/out */ =20 char name[DM_NAME_LEN]; /* device name */ char uuid[DM_UUID_LEN]; /* unique identifier for * the block device */ - char data[7]; /* padding or data, must be zero in strict mode */ + union { + /* valid if DM_VERSION_MAJOR is used */ + char data[7]; /* padding or data */ + /* valid if DM_VERSION_MAJOR_STRICT is used */ + struct { + char _padding[3]; /* padding, must be zeroed */ + __u32 diskseq_high; /* in/out: high 4 bytes of the diskseq */ + } __attribute__((packed)); + }; }; =20 +__attribute__((always_inline)) static inline __u64 +dm_get_diskseq(const struct dm_ioctl *_i) +{ + return (__u64)_i->diskseq_high << 32 | (__u64)_i->diskseq_low; +} + +__attribute__((always_inline)) static inline void +dm_set_diskseq(struct dm_ioctl *_i, __u64 _diskseq) +{ + _i->diskseq_low =3D (__u32)(_diskseq & 0xFFFFFFFFU); + _i->diskseq_high =3D (__u32)(_diskseq >> 32); +} + /* * Used to specify tables. These structures appear after the * dm_ioctl. --=20 Sincerely, Demi Marie Obenour (she/her/hers) Invisible Things Lab