From patchwork Tue Jun 13 14:49:16 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 13278924 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 76F7EEB64D0 for ; Tue, 13 Jun 2023 14:49:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242745AbjFMOtl (ORCPT ); Tue, 13 Jun 2023 10:49:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58082 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242656AbjFMOtf (ORCPT ); Tue, 13 Jun 2023 10:49:35 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 84B861BC6; Tue, 13 Jun 2023 07:49:34 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id F2BC263640; Tue, 13 Jun 2023 14:49:33 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 58F8DC433F0; Tue, 13 Jun 2023 14:49:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1686667773; bh=2SpQOuQjIqP4mY71XZvOryMwD2mX4CVEV9PM1I4GpgU=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=fV6+aUd0jMyX7iUSCa7YtHIRPJ4UN9iwQh84M2QjASbRMzv8zJItHdWmS1tvOVtil 9RPTzY6/fl7RZmbRCc3MDuGniV9dY2/3pxV0+0U7CI6vkFg7/QShMQlrPwOIgb5CKT Ff23Dr39miGOmiCJOw16u5mPpO4fs4LL0I68L6rrTsD/BD7ypRs2HIh3Nqpiv6xlSM iPn3d0FTsI3qCqaoPryToRj9h4C8wxAFgQkn35ljAiS0E8DSjn+3Izhwhme91SNaOa CmT/5a6ODVjn6V6fetyXwIPB5zmJWQi3jP7JMl76s+JgxwLSPsbZf7Tcxl6F9wyyQ+ B8Kmk7M3RwNwQ== From: Christian Brauner Date: Tue, 13 Jun 2023 16:49:16 +0200 Subject: [PATCH v3 1/3] ovl: check type and offset of struct vfsmount in ovl_entry MIME-Version: 1.0 Message-Id: <20230605-fs-overlayfs-mount_api-v3-1-730d9646b27d@kernel.org> References: <20230605-fs-overlayfs-mount_api-v3-0-730d9646b27d@kernel.org> In-Reply-To: <20230605-fs-overlayfs-mount_api-v3-0-730d9646b27d@kernel.org> To: Amir Goldstein , Miklos Szeredi Cc: linux-fsdevel@vger.kernel.org, linux-unionfs@vger.kernel.org, Christian Brauner X-Mailer: b4 0.13-dev-c6835 X-Developer-Signature: v=1; a=openpgp-sha256; l=1749; i=brauner@kernel.org; h=from:subject:message-id; bh=2SpQOuQjIqP4mY71XZvOryMwD2mX4CVEV9PM1I4GpgU=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMaR0NP76Z3zR8CV/xlWtSeuTC5cet8x5scjAIEuo40Esl+dK 59jbHaUsDGJcDLJiiiwO7Sbhcst5KjYbZWrAzGFlAhnCwMUpABOx7GFkmKWgl2H0pTLm8OdPMwoMvo Ulx/1fHuHz7sW1GYt7nf5Y3GJkuFrtnMjea7CCZ293ecr3mWmPLC6uP25qEPq4Jc6udY0hIwA= X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Porting overlayfs to the new amount api I started experiencing random crashes that couldn't be explained easily. So after much debugging and reasoning it became clear that struct ovl_entry requires the point to struct vfsmount to be the first member and of type struct vfsmount. During the port I added a new member at the beginning of struct ovl_entry which broke all over the place in the form of random crashes and cache corruptions. While there's a comment in ovl_free_fs() to the effect of "Hack! Reuse ofs->layers as a vfsmount array before freeing it" there's no such comment on struct ovl_entry which makes this easy to trip over. Add a comment and two static asserts for both the offset and the type of pointer in struct ovl_entry. Signed-off-by: Christian Brauner --- fs/overlayfs/ovl_entry.h | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h index c6c7d09b494e..e5207c4bf5b8 100644 --- a/fs/overlayfs/ovl_entry.h +++ b/fs/overlayfs/ovl_entry.h @@ -32,6 +32,7 @@ struct ovl_sb { }; struct ovl_layer { + /* ovl_free_fs() relies on @mnt being the first member! */ struct vfsmount *mnt; /* Trap in ovl inode cache */ struct inode *trap; @@ -42,6 +43,14 @@ struct ovl_layer { int fsid; }; +/* + * ovl_free_fs() relies on @mnt being the first member when unmounting + * the private mounts created for each layer. Let's check both the + * offset and type. + */ +static_assert(offsetof(struct ovl_layer, mnt) == 0); +static_assert(__same_type(typeof_member(struct ovl_layer, mnt), struct vfsmount *)); + struct ovl_path { const struct ovl_layer *layer; struct dentry *dentry; From patchwork Tue Jun 13 14:49:17 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 13278925 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 84ED7EB64DA for ; Tue, 13 Jun 2023 14:50:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242630AbjFMOuB (ORCPT ); Tue, 13 Jun 2023 10:50:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58116 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242698AbjFMOtj (ORCPT ); Tue, 13 Jun 2023 10:49:39 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 861A419B3; Tue, 13 Jun 2023 07:49:36 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 7D99F63649; Tue, 13 Jun 2023 14:49:35 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D3E3DC433F1; Tue, 13 Jun 2023 14:49:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1686667774; bh=mR8KImFQwgQk9Ddz6ZLC2b+Vf1MzmIFN6Pn2N3bf1GQ=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=f6cny0aMbAwh4Jy1lu5a49I22AV8udOgXVe2iVwKGwHiBFzUFLH9x6WovCbV1T9Rh ZfphwCCCT8yn3b3+bGNT03CMfQeNHsUP1FouvzdVR+k8vVqRYaSB8ClVF3svzPqacz LkPS7yIeBtOFIdWq6yUUoJQxKX1C99qSgqFp6LDNXe7k07GU6oAJ4FVX2nLneWIrQc hKs7BXI2+l/NeeBSUSpCy3n0haUJ+UyVKqcLwjO4vwlee8cbqaCxZ1H4qGs6vD/vUF GiVnH7NAaoZI80JP4sdY/KKBzvwA9oSrAdSAC1437YWaxIqEqj1f03+qXZQbnl8QSm cxiwIcEUC1OOQ== From: Christian Brauner Date: Tue, 13 Jun 2023 16:49:17 +0200 Subject: [PATCH v3 2/3] ovl: port to new mount api MIME-Version: 1.0 Message-Id: <20230605-fs-overlayfs-mount_api-v3-2-730d9646b27d@kernel.org> References: <20230605-fs-overlayfs-mount_api-v3-0-730d9646b27d@kernel.org> In-Reply-To: <20230605-fs-overlayfs-mount_api-v3-0-730d9646b27d@kernel.org> To: Amir Goldstein , Miklos Szeredi Cc: linux-fsdevel@vger.kernel.org, linux-unionfs@vger.kernel.org, Christian Brauner X-Mailer: b4 0.13-dev-c6835 X-Developer-Signature: v=1; a=openpgp-sha256; l=20251; i=brauner@kernel.org; h=from:subject:message-id; bh=mR8KImFQwgQk9Ddz6ZLC2b+Vf1MzmIFN6Pn2N3bf1GQ=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMaR0NP6y6M99ql8RZOWxOaz3afTF5kf/NJWPr4s0EauW4Ff6 vsO+o5SFQYyLQVZMkcWh3SRcbjlPxWajTA2YOaxMIEMYuDgFYCLLxRkZHlbwmDUKr32Y66njxeZWsH 2hBttW7qTXYt3b+H+mTbrXzPCHdyp3/wSXd/k1Ct9e5Fz6MX+NYf2eJbx2TBJq07fnyrPxAgA= X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org We recently ported util-linux to the new mount api. Now the mount(8) tool will by default use the new mount api. While trying hard to fall back to the old mount api gracefully there are still cases where we run into issues that are difficult to handle nicely. Now with mount(8) and libmount supporting the new mount api I expect an increase in the number of bug reports and issues we're going to see with filesystems that don't yet support the new mount api. So it's time we rectify this. Signed-off-by: Christian Brauner --- fs/overlayfs/ovl_entry.h | 2 +- fs/overlayfs/super.c | 557 ++++++++++++++++++++++++++--------------------- 2 files changed, 305 insertions(+), 254 deletions(-) diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h index e5207c4bf5b8..c72433c06006 100644 --- a/fs/overlayfs/ovl_entry.h +++ b/fs/overlayfs/ovl_entry.h @@ -12,7 +12,7 @@ struct ovl_config { bool default_permissions; bool redirect_dir; bool redirect_follow; - const char *redirect_mode; + unsigned redirect_mode; bool index; bool uuid; bool nfs_export; diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index d9be5d318e1b..3392dc5d2082 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -16,6 +16,8 @@ #include #include #include +#include +#include #include "overlayfs.h" MODULE_AUTHOR("Miklos Szeredi "); @@ -59,6 +61,79 @@ module_param_named(metacopy, ovl_metacopy_def, bool, 0644); MODULE_PARM_DESC(metacopy, "Default to on or off for the metadata only copy up feature"); +enum { + Opt_lowerdir, + Opt_upperdir, + Opt_workdir, + Opt_default_permissions, + Opt_redirect_dir, + Opt_index, + Opt_uuid, + Opt_nfs_export, + Opt_userxattr, + Opt_xino, + Opt_metacopy, + Opt_volatile, +}; + +static const struct constant_table ovl_parameter_bool[] = { + { "on", true }, + { "off", false }, + {} +}; + +static const struct constant_table ovl_parameter_xino[] = { + { "on", OVL_XINO_ON }, + { "off", OVL_XINO_OFF }, + { "auto", OVL_XINO_AUTO }, + {} +}; + +enum { + OVL_REDIRECT_DIR_ON, + OVL_REDIRECT_DIR_OFF, + OVL_REDIRECT_DIR_FOLLOW, + OVL_REDIRECT_DIR_NOFOLLOW, +}; + +static const struct constant_table ovl_parameter_redirect_dir[] = { + { "on", OVL_REDIRECT_DIR_ON }, + { "off", OVL_REDIRECT_DIR_OFF }, + { "follow", OVL_REDIRECT_DIR_FOLLOW }, + { "nofollow", OVL_REDIRECT_DIR_NOFOLLOW }, + {} +}; + +static const char *ovl_redirect_mode(struct ovl_config *config) +{ + return ovl_parameter_redirect_dir[config->redirect_mode].name; +} + +static const struct fs_parameter_spec ovl_parameter_spec[] = { + fsparam_string("lowerdir", Opt_lowerdir), + fsparam_string("upperdir", Opt_upperdir), + fsparam_string("workdir", Opt_workdir), + fsparam_flag("default_permissions", Opt_default_permissions), + fsparam_enum("redirect_dir", Opt_redirect_dir, ovl_parameter_redirect_dir), + fsparam_enum("index", Opt_index, ovl_parameter_bool), + fsparam_enum("uuid", Opt_uuid, ovl_parameter_bool), + fsparam_enum("nfs_export", Opt_nfs_export, ovl_parameter_bool), + fsparam_flag("userxattr", Opt_userxattr), + fsparam_enum("xino", Opt_xino, ovl_parameter_xino), + fsparam_enum("metacopy", Opt_metacopy, ovl_parameter_bool), + fsparam_flag("volatile", Opt_volatile), + {} +}; + +#define OVL_METACOPY_SET BIT(0) +#define OVL_REDIRECT_SET BIT(1) +#define OVL_NFS_EXPORT_SET BIT(2) +#define OVL_INDEX_SET BIT(3) + +struct ovl_fs_context { + u8 set; +}; + static struct dentry *ovl_d_real(struct dentry *dentry, const struct inode *inode) { @@ -243,7 +318,6 @@ static void ovl_free_fs(struct ovl_fs *ofs) kfree(ofs->config.lowerdir); kfree(ofs->config.upperdir); kfree(ofs->config.workdir); - kfree(ofs->config.redirect_mode); if (ofs->creator_cred) put_cred(ofs->creator_cred); kfree(ofs); @@ -253,7 +327,8 @@ static void ovl_put_super(struct super_block *sb) { struct ovl_fs *ofs = sb->s_fs_info; - ovl_free_fs(ofs); + if (ofs) + ovl_free_fs(ofs); } /* Sync real dirty inodes in upper filesystem (if it exists) */ @@ -357,6 +432,7 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry) { struct super_block *sb = dentry->d_sb; struct ovl_fs *ofs = sb->s_fs_info; + const char *redirect_mode; seq_show_option(m, "lowerdir", ofs->config.lowerdir); if (ofs->config.upperdir) { @@ -365,8 +441,9 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry) } if (ofs->config.default_permissions) seq_puts(m, ",default_permissions"); - if (strcmp(ofs->config.redirect_mode, ovl_redirect_mode_def()) != 0) - seq_printf(m, ",redirect_dir=%s", ofs->config.redirect_mode); + redirect_mode = ovl_redirect_mode(&ofs->config); + if (strcmp(redirect_mode, ovl_redirect_mode_def()) != 0) + seq_printf(m, ",redirect_dir=%s", redirect_mode); if (ofs->config.index != ovl_index_def) seq_printf(m, ",index=%s", ofs->config.index ? "on" : "off"); if (!ofs->config.uuid) @@ -386,27 +463,6 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry) return 0; } -static int ovl_remount(struct super_block *sb, int *flags, char *data) -{ - struct ovl_fs *ofs = sb->s_fs_info; - struct super_block *upper_sb; - int ret = 0; - - if (!(*flags & SB_RDONLY) && ovl_force_readonly(ofs)) - return -EROFS; - - if (*flags & SB_RDONLY && !sb_rdonly(sb)) { - upper_sb = ovl_upper_mnt(ofs)->mnt_sb; - if (ovl_should_sync(ofs)) { - down_read(&upper_sb->s_umount); - ret = sync_filesystem(upper_sb); - up_read(&upper_sb->s_umount); - } - } - - return ret; -} - static const struct super_operations ovl_super_operations = { .alloc_inode = ovl_alloc_inode, .free_inode = ovl_free_inode, @@ -416,216 +472,42 @@ static const struct super_operations ovl_super_operations = { .sync_fs = ovl_sync_fs, .statfs = ovl_statfs, .show_options = ovl_show_options, - .remount_fs = ovl_remount, -}; - -enum { - OPT_LOWERDIR, - OPT_UPPERDIR, - OPT_WORKDIR, - OPT_DEFAULT_PERMISSIONS, - OPT_REDIRECT_DIR, - OPT_INDEX_ON, - OPT_INDEX_OFF, - OPT_UUID_ON, - OPT_UUID_OFF, - OPT_NFS_EXPORT_ON, - OPT_USERXATTR, - OPT_NFS_EXPORT_OFF, - OPT_XINO_ON, - OPT_XINO_OFF, - OPT_XINO_AUTO, - OPT_METACOPY_ON, - OPT_METACOPY_OFF, - OPT_VOLATILE, - OPT_ERR, -}; - -static const match_table_t ovl_tokens = { - {OPT_LOWERDIR, "lowerdir=%s"}, - {OPT_UPPERDIR, "upperdir=%s"}, - {OPT_WORKDIR, "workdir=%s"}, - {OPT_DEFAULT_PERMISSIONS, "default_permissions"}, - {OPT_REDIRECT_DIR, "redirect_dir=%s"}, - {OPT_INDEX_ON, "index=on"}, - {OPT_INDEX_OFF, "index=off"}, - {OPT_USERXATTR, "userxattr"}, - {OPT_UUID_ON, "uuid=on"}, - {OPT_UUID_OFF, "uuid=off"}, - {OPT_NFS_EXPORT_ON, "nfs_export=on"}, - {OPT_NFS_EXPORT_OFF, "nfs_export=off"}, - {OPT_XINO_ON, "xino=on"}, - {OPT_XINO_OFF, "xino=off"}, - {OPT_XINO_AUTO, "xino=auto"}, - {OPT_METACOPY_ON, "metacopy=on"}, - {OPT_METACOPY_OFF, "metacopy=off"}, - {OPT_VOLATILE, "volatile"}, - {OPT_ERR, NULL} }; -static char *ovl_next_opt(char **s) +static int ovl_set_redirect_mode(struct ovl_config *config) { - char *sbegin = *s; - char *p; - - if (sbegin == NULL) - return NULL; - - for (p = sbegin; *p; p++) { - if (*p == '\\') { - p++; - if (!*p) - break; - } else if (*p == ',') { - *p = '\0'; - *s = p + 1; - return sbegin; - } - } - *s = NULL; - return sbegin; -} - -static int ovl_parse_redirect_mode(struct ovl_config *config, const char *mode) -{ - if (strcmp(mode, "on") == 0) { + switch (config->redirect_mode) { + case OVL_REDIRECT_DIR_ON: config->redirect_dir = true; /* * Does not make sense to have redirect creation without * redirect following. */ config->redirect_follow = true; - } else if (strcmp(mode, "follow") == 0) { + return 0; + case OVL_REDIRECT_DIR_FOLLOW: config->redirect_follow = true; - } else if (strcmp(mode, "off") == 0) { + return 0; + case OVL_REDIRECT_DIR_OFF: if (ovl_redirect_always_follow) config->redirect_follow = true; - } else if (strcmp(mode, "nofollow") != 0) { - pr_err("bad mount option \"redirect_dir=%s\"\n", - mode); - return -EINVAL; + return 0; + case OVL_REDIRECT_DIR_NOFOLLOW: + return 0; } - return 0; + pr_err("invalid \"redirect_dir\" mount option\n"); + return -EINVAL; } -static int ovl_parse_opt(char *opt, struct ovl_config *config) +static int ovl_fs_params_verify(const struct ovl_fs_context *ctx, + struct ovl_config *config) { - char *p; int err; - bool metacopy_opt = false, redirect_opt = false; - bool nfs_export_opt = false, index_opt = false; - - config->redirect_mode = kstrdup(ovl_redirect_mode_def(), GFP_KERNEL); - if (!config->redirect_mode) - return -ENOMEM; - - while ((p = ovl_next_opt(&opt)) != NULL) { - int token; - substring_t args[MAX_OPT_ARGS]; - - if (!*p) - continue; - - token = match_token(p, ovl_tokens, args); - switch (token) { - case OPT_UPPERDIR: - kfree(config->upperdir); - config->upperdir = match_strdup(&args[0]); - if (!config->upperdir) - return -ENOMEM; - break; - - case OPT_LOWERDIR: - kfree(config->lowerdir); - config->lowerdir = match_strdup(&args[0]); - if (!config->lowerdir) - return -ENOMEM; - break; - - case OPT_WORKDIR: - kfree(config->workdir); - config->workdir = match_strdup(&args[0]); - if (!config->workdir) - return -ENOMEM; - break; - - case OPT_DEFAULT_PERMISSIONS: - config->default_permissions = true; - break; - - case OPT_REDIRECT_DIR: - kfree(config->redirect_mode); - config->redirect_mode = match_strdup(&args[0]); - if (!config->redirect_mode) - return -ENOMEM; - redirect_opt = true; - break; - - case OPT_INDEX_ON: - config->index = true; - index_opt = true; - break; - - case OPT_INDEX_OFF: - config->index = false; - index_opt = true; - break; - - case OPT_UUID_ON: - config->uuid = true; - break; - - case OPT_UUID_OFF: - config->uuid = false; - break; - - case OPT_NFS_EXPORT_ON: - config->nfs_export = true; - nfs_export_opt = true; - break; - - case OPT_NFS_EXPORT_OFF: - config->nfs_export = false; - nfs_export_opt = true; - break; - - case OPT_XINO_ON: - config->xino = OVL_XINO_ON; - break; - - case OPT_XINO_OFF: - config->xino = OVL_XINO_OFF; - break; - - case OPT_XINO_AUTO: - config->xino = OVL_XINO_AUTO; - break; - - case OPT_METACOPY_ON: - config->metacopy = true; - metacopy_opt = true; - break; - - case OPT_METACOPY_OFF: - config->metacopy = false; - metacopy_opt = true; - break; - - case OPT_VOLATILE: - config->ovl_volatile = true; - break; - - case OPT_USERXATTR: - config->userxattr = true; - break; - - default: - pr_err("unrecognized mount option \"%s\" or missing value\n", - p); - return -EINVAL; - } - } + bool metacopy_opt = ctx->set & OVL_METACOPY_SET; + bool redirect_opt = ctx->set & OVL_REDIRECT_SET; + bool nfs_export_opt = ctx->set & OVL_NFS_EXPORT_SET; + bool index_opt = ctx->set & OVL_INDEX_SET; /* Workdir/index are useless in non-upper mount */ if (!config->upperdir) { @@ -647,7 +529,7 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config) config->ovl_volatile = false; } - err = ovl_parse_redirect_mode(config, config->redirect_mode); + err = ovl_set_redirect_mode(config); if (err) return err; @@ -662,7 +544,7 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config) if (config->metacopy && !config->redirect_dir) { if (metacopy_opt && redirect_opt) { pr_err("conflicting options: metacopy=on,redirect_dir=%s\n", - config->redirect_mode); + ovl_redirect_mode(config)); return -EINVAL; } if (redirect_opt) { @@ -671,7 +553,7 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config) * in this conflict. */ pr_info("disabling metacopy due to redirect_dir=%s\n", - config->redirect_mode); + ovl_redirect_mode(config)); config->metacopy = false; } else { /* Automatically enable redirect otherwise. */ @@ -728,7 +610,7 @@ static int ovl_parse_opt(char *opt, struct ovl_config *config) if (config->userxattr) { if (config->redirect_follow && redirect_opt) { pr_err("conflicting options: userxattr,redirect_dir=%s\n", - config->redirect_mode); + ovl_redirect_mode(config)); return -EINVAL; } if (config->metacopy && metacopy_opt) { @@ -1926,12 +1808,128 @@ static struct dentry *ovl_get_root(struct super_block *sb, return root; } -static int ovl_fill_super(struct super_block *sb, void *data, int silent) +static int ovl_parse_param(struct fs_context *fc, struct fs_parameter *param) +{ + int err = 0; + struct fs_parse_result result; + struct ovl_fs *ofs = fc->s_fs_info; + struct ovl_config *config = &ofs->config; + struct ovl_fs_context *ctx = fc->fs_private; + char *dup; + int opt; + + /* + * On remount overlayfs has always ignored all mount options no + * matter if malformed or not so for backwards compatibility we + * do the same here. + */ + if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE) + return 0; + + opt = fs_parse(fc, ovl_parameter_spec, param, &result); + if (opt < 0) + return opt; + + switch (opt) { + case Opt_lowerdir: + dup = kstrdup(param->string, GFP_KERNEL); + if (!dup) { + err = -ENOMEM; + break; + } + + kfree(config->lowerdir); + config->lowerdir = dup; + break; + case Opt_upperdir: + dup = kstrdup(param->string, GFP_KERNEL); + if (!dup) { + err = -ENOMEM; + break; + } + + kfree(config->upperdir); + config->upperdir = dup; + break; + case Opt_workdir: + dup = kstrdup(param->string, GFP_KERNEL); + if (!dup) { + err = -ENOMEM; + break; + } + + kfree(config->workdir); + config->workdir = dup; + break; + case Opt_default_permissions: + config->default_permissions = true; + break; + case Opt_index: + config->index = result.uint_32; + ctx->set |= OVL_INDEX_SET; + break; + case Opt_uuid: + config->uuid = result.uint_32; + break; + case Opt_nfs_export: + config->nfs_export = result.uint_32; + ctx->set |= OVL_NFS_EXPORT_SET; + break; + case Opt_metacopy: + config->metacopy = result.uint_32; + ctx->set |= OVL_METACOPY_SET; + break; + case Opt_userxattr: + config->userxattr = true; + break; + case Opt_volatile: + config->ovl_volatile = true; + break; + case Opt_xino: + config->xino = result.uint_32; + break; + case Opt_redirect_dir: + config->redirect_mode = result.uint_32; + ctx->set |= OVL_REDIRECT_SET; + break; + default: + pr_err("unrecognized mount option \"%s\" or missing value\n", param->key); + return -EINVAL; + } + + return err; +} + + +static int ovl_reconfigure(struct fs_context *fc) { - struct path upperpath = { }; + struct super_block *sb = fc->root->d_sb; + struct ovl_fs *ofs = sb->s_fs_info; + struct super_block *upper_sb; + int ret = 0; + + if (!(fc->sb_flags & SB_RDONLY) && ovl_force_readonly(ofs)) + return -EROFS; + + if (fc->sb_flags & SB_RDONLY && !sb_rdonly(sb)) { + upper_sb = ovl_upper_mnt(ofs)->mnt_sb; + if (ovl_should_sync(ofs)) { + down_read(&upper_sb->s_umount); + ret = sync_filesystem(upper_sb); + up_read(&upper_sb->s_umount); + } + } + + return ret; +} + +static int ovl_fill_super(struct super_block *sb, struct fs_context *fc) +{ + struct ovl_fs *ofs = sb->s_fs_info; + struct ovl_fs_context *ctx = fc->fs_private; + struct path upperpath = {}; struct dentry *root_dentry; struct ovl_entry *oe; - struct ovl_fs *ofs; struct ovl_layer *layers; struct cred *cred; char *splitlower = NULL; @@ -1939,36 +1937,24 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) int err; err = -EIO; - if (WARN_ON(sb->s_user_ns != current_user_ns())) - goto out; + if (WARN_ON(fc->user_ns != current_user_ns())) + goto out_err; + ofs->share_whiteout = true; sb->s_d_op = &ovl_dentry_operations; - err = -ENOMEM; - ofs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL); - if (!ofs) - goto out; - err = -ENOMEM; ofs->creator_cred = cred = prepare_creds(); if (!cred) goto out_err; - /* Is there a reason anyone would want not to share whiteouts? */ - ofs->share_whiteout = true; - - ofs->config.index = ovl_index_def; - ofs->config.uuid = true; - ofs->config.nfs_export = ovl_nfs_export_def; - ofs->config.xino = ovl_xino_def(); - ofs->config.metacopy = ovl_metacopy_def; - err = ovl_parse_opt((char *) data, &ofs->config); + err = ovl_fs_params_verify(ctx, &ofs->config); if (err) goto out_err; err = -EINVAL; if (!ofs->config.lowerdir) { - if (!silent) + if (fc->sb_flags & SB_SILENT) pr_err("missing 'lowerdir'\n"); goto out_err; } @@ -2113,25 +2099,90 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) out_free_oe: ovl_free_entry(oe); out_err: - kfree(splitlower); - path_put(&upperpath); - ovl_free_fs(ofs); -out: return err; } -static struct dentry *ovl_mount(struct file_system_type *fs_type, int flags, - const char *dev_name, void *raw_data) +static int ovl_get_tree(struct fs_context *fc) +{ + return get_tree_nodev(fc, ovl_fill_super); +} + +static inline void ovl_fs_context_free(struct ovl_fs_context *ctx) +{ + kfree(ctx); +} + +static void ovl_free(struct fs_context *fc) { - return mount_nodev(fs_type, flags, raw_data, ovl_fill_super); + struct ovl_fs *ofs = fc->s_fs_info; + struct ovl_fs_context *ctx = fc->fs_private; + + /* + * ofs is stored in the fs_context when it is initialized. + * ofs is transferred to the superblock on a successful mount, + * but if an error occurs before the transfer we have to free + * it here. + */ + if (ofs) + ovl_free_fs(ofs); + + if (ctx) + ovl_fs_context_free(ctx); +} + +static const struct fs_context_operations ovl_context_ops = { + .parse_param = ovl_parse_param, + .get_tree = ovl_get_tree, + .reconfigure = ovl_reconfigure, + .free = ovl_free, +}; + +/* + * This is called during fsopen() and will record the user namespace of + * the caller in fc->user_ns since we've raised FS_USERNS_MOUNT. We'll + * need it when we actually create the superblock to verify that the + * process creating the superblock is in the same user namespace as + * process that called fsopen(). + */ +static int ovl_init_fs_context(struct fs_context *fc) +{ + struct ovl_fs_context *ctx; + struct ovl_fs *ofs; + + ctx = kzalloc(sizeof(*ctx), GFP_KERNEL_ACCOUNT); + if (!ctx) + return -ENOMEM; + + ofs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL); + if (!ofs) { + ovl_fs_context_free(ctx); + return -ENOMEM; + } + + if (strcmp(ovl_redirect_mode_def(), "on") == 0) + ofs->config.redirect_mode = OVL_REDIRECT_DIR_ON; + else + ofs->config.redirect_mode = OVL_REDIRECT_DIR_OFF; + + ofs->config.index = ovl_index_def; + ofs->config.uuid = true; + ofs->config.nfs_export = ovl_nfs_export_def; + ofs->config.xino = ovl_xino_def(); + ofs->config.metacopy = ovl_metacopy_def; + + fc->s_fs_info = ofs; + fc->fs_private = ctx; + fc->ops = &ovl_context_ops; + return 0; } static struct file_system_type ovl_fs_type = { - .owner = THIS_MODULE, - .name = "overlay", - .fs_flags = FS_USERNS_MOUNT, - .mount = ovl_mount, - .kill_sb = kill_anon_super, + .owner = THIS_MODULE, + .name = "overlay", + .init_fs_context = ovl_init_fs_context, + .parameters = ovl_parameter_spec, + .fs_flags = FS_USERNS_MOUNT, + .kill_sb = kill_anon_super, }; MODULE_ALIAS_FS("overlay"); From patchwork Tue Jun 13 14:49:18 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 13278926 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 3AB39EB64D7 for ; Tue, 13 Jun 2023 14:50:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242695AbjFMOuC (ORCPT ); Tue, 13 Jun 2023 10:50:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58084 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238917AbjFMOtk (ORCPT ); Tue, 13 Jun 2023 10:49:40 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8007619BC; Tue, 13 Jun 2023 07:49:37 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 05FAF6364A; Tue, 13 Jun 2023 14:49:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5CD22C433F2; Tue, 13 Jun 2023 14:49:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1686667776; bh=6ASy+MOp7tAn7rzcvmLybrlXz5CPjUFSAqv9O9MzpYQ=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=JqsqsaHw2/f/GpzWfIlfnuKIiD6c4lzeLlI+yY85StJVBnLl31Bcx7T//TXU0auhv sNogGCSCywl/BBoOUDc345/EJmYNOtBRilbRUpLF0BHxgf+qPNNq6prqS3suHP9FHp 2qZAqH0fCEShpPVuLCmJ9yr4zBldNKsAAF9ZaiJeBr+f2tT6Q9gPjTaDWJjog+iS6F W9lkzk6wuiVVrgyrnouYlii2tPkj21zADEJIplV7fMpdPg8ZOlXpvVj+BMNDccjqDK dJgStytAfoG8SopgplpOhOZoCHXMUBRlEVhH+vySwn5KqpKFwG/v3x2OesmZmgEkUq rNWf+4sW84gIg== From: Christian Brauner Date: Tue, 13 Jun 2023 16:49:18 +0200 Subject: [PATCH v3 3/3] ovl: change layer mount option handling MIME-Version: 1.0 Message-Id: <20230605-fs-overlayfs-mount_api-v3-3-730d9646b27d@kernel.org> References: <20230605-fs-overlayfs-mount_api-v3-0-730d9646b27d@kernel.org> In-Reply-To: <20230605-fs-overlayfs-mount_api-v3-0-730d9646b27d@kernel.org> To: Amir Goldstein , Miklos Szeredi Cc: linux-fsdevel@vger.kernel.org, linux-unionfs@vger.kernel.org, Christian Brauner X-Mailer: b4 0.13-dev-c6835 X-Developer-Signature: v=1; a=openpgp-sha256; l=37512; i=brauner@kernel.org; h=from:subject:message-id; bh=6ASy+MOp7tAn7rzcvmLybrlXz5CPjUFSAqv9O9MzpYQ=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMaR0NP4qfrHxSsPL6aKtk4WfK3JUXN/7TumDdLLZF2XdJdLT p/640VHKwiDGxSArpsji0G4SLrecp2KzUaYGzBxWJpAhDFycAjCR/bsZGZpupK+PiLuzK+mUeb3oo7 q7b5+d5dgb3hzZ+mqVe0+8zXNGhkcvn50IZ9rR57AgxyaxepreLuM/tntPfQn3yE2rqnpfwggA X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org We ran into issues where mount(8) passed multiple lower layers as one big string through fsconfig(). But the fsconfig() FSCONFIG_SET_STRING option is limited to 256 bytes in strndup_user(). While this would be fixable by extending the fsconfig() buffer I'd rather encourage users to append layers via multiple fsconfig() calls as the interface allows nicely for this. This has also been requested as a feature before. With this port to the new mount api the following will be possible: fsconfig(fs_fd, FSCONFIG_SET_STRING, "lowerdir", "/lower1", 0); /* set upper layer */ fsconfig(fs_fd, FSCONFIG_SET_STRING, "upperdir", "/upper", 0); /* append "/lower2", "/lower3", and "/lower4" */ fsconfig(fs_fd, FSCONFIG_SET_STRING, "lowerdir", ":/lower2:/lower3:/lower4", 0); /* turn index feature on */ fsconfig(fs_fd, FSCONFIG_SET_STRING, "index", "on", 0); /* append "/lower5" */ fsconfig(fs_fd, FSCONFIG_SET_STRING, "lowerdir", ":/lower5", 0); Specifying ':' would have been rejected so this isn't a regression. And we can't simply use "lowerdir=/lower" to append on top of existing layers as "lowerdir=/lower,lowerdir=/other-lower" would make "/other-lower" the only lower layer so we'd break uapi if we changed this. So the ':' prefix seems a good compromise. Users can choose to specify multiple layers at once or individual layers. A layer is appended if it starts with ":". This requires that the user has already added at least one layer before. If lowerdir is specified again without a leading ":" then all previous layers are dropped and replaced with the new layers. If lowerdir is specified and empty than all layers are simply dropped. An additional change is that overlayfs will now parse and resolve layers right when they are specified in fsconfig() instead of deferring until super block creation. This allows users to receive early errors. It also allows users to actually use up to 500 layers something which was theoretically possible but ended up not working due to the mount option string passed via mount(2) being too large. This also allows a more privileged process to set config options for a lesser privileged process as the creds for fsconfig() and the creds for fsopen() can differ. We could restrict that they match by enforcing that the creds of fsopen() and fsconfig() match but I don't see why that needs to be the case and allows for a good delegation mechanism. Plus, in the future it means we're able to extend overlayfs mount options and allow users to specify layers via file descriptors instead of paths: fsconfig(FSCONFIG_SET_PATH{_EMPTY}, "lowerdir", "lower1", dirfd); /* append */ fsconfig(FSCONFIG_SET_PATH{_EMPTY}, "lowerdir", "lower2", dirfd); /* append */ fsconfig(FSCONFIG_SET_PATH{_EMPTY}, "lowerdir", "lower3", dirfd); /* clear all layers specified until now */ fsconfig(FSCONFIG_SET_STRING, "lowerdir", NULL, 0); This would be especially nice if users create an overlayfs mount on top of idmapped layers or just in general private mounts created via open_tree(OPEN_TREE_CLONE). Those mounts would then never have to appear anywhere in the filesystem. But for now just do the minimal thing. We should probably aim to move more validation into ovl_fs_parse_param() so users get errors before fsconfig(FSCONFIG_CMD_CREATE). But that can be done in additional patches later. This is now also rebased on top of the lazy lowerdata lookup which allows the specificatin of data only layers using the new "::" syntax. The rules are simple. A data only layers cannot be followed by any regular layers and data layers must be preceeded by at least one regular layer. Parsing the lowerdir mount option must change because of this. The original patchset used the old lowerdir parsing function to split a lowerdir mount option string such as: lowerdir=/lower1:/lower2::/lower3::/lower4 simply replacing each non-escaped ":" by "\0". So sequences of non-escaped ":" were counted as layers. For example, the previous lowerdir mount option above would've counted 6 layers instead of 4 and a lowerdir mount option such as: lowerdir="/lower1:/lower2::/lower3::/lower4:::::::::::::::::::::::::::" would be counted as 33 layers. Other than being ugly this didn't matter much because kern_path() would reject the first "\0" layer. However, this overcounting of layers becomes problematic when we base allocations on it where we very much only want to allocate space for 4 layers instead of 33. So the new parsing function rejects non-escaped sequences of colons other than ":" and "::" immediately instead of relying on kern_path(). Link: https://github.com/util-linux/util-linux/issues/2287 Link: https://github.com/util-linux/util-linux/issues/1992 Link: https://bugs.archlinux.org/task/78702 Link: https://lore.kernel.org/linux-unionfs/20230530-klagen-zudem-32c0908c2108@brauner Signed-off-by: Christian Brauner --- fs/overlayfs/Makefile | 2 +- fs/overlayfs/overlayfs.h | 23 +++ fs/overlayfs/ovl_entry.h | 3 +- fs/overlayfs/params.c | 388 +++++++++++++++++++++++++++++++++++++++++++++++ fs/overlayfs/super.c | 376 +++++++++++++++------------------------------ 5 files changed, 534 insertions(+), 258 deletions(-) diff --git a/fs/overlayfs/Makefile b/fs/overlayfs/Makefile index 9164c585eb2f..4e173d56b11f 100644 --- a/fs/overlayfs/Makefile +++ b/fs/overlayfs/Makefile @@ -6,4 +6,4 @@ obj-$(CONFIG_OVERLAY_FS) += overlay.o overlay-objs := super.o namei.o util.o inode.o file.o dir.o readdir.o \ - copy_up.o export.o + copy_up.o export.o params.o diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h index fcac4e2c56ab..7659ea6e02cb 100644 --- a/fs/overlayfs/overlayfs.h +++ b/fs/overlayfs/overlayfs.h @@ -119,6 +119,29 @@ struct ovl_fh { #define OVL_FH_FID_OFFSET (OVL_FH_WIRE_OFFSET + \ offsetof(struct ovl_fb, fid)) +/* params.c */ +#define OVL_MAX_STACK 500 + +struct ovl_fs_context_layer { + char *name; + struct path path; +}; + +struct ovl_fs_context { + struct path upper; + struct path work; + size_t capacity; + size_t nr; /* includes nr_data */ + size_t nr_data; + u8 set; + struct ovl_fs_context_layer *lower; +}; + +int ovl_parse_param_upperdir(const char *name, struct fs_context *fc, + bool workdir); +int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc); +void ovl_parse_param_drop_lowerdir(struct ovl_fs_context *ctx); + extern const char *const ovl_xattr_table[][2]; static inline const char *ovl_xattr(struct ovl_fs *ofs, enum ovl_xattr ox) { diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h index c72433c06006..7888ab33730b 100644 --- a/fs/overlayfs/ovl_entry.h +++ b/fs/overlayfs/ovl_entry.h @@ -6,7 +6,6 @@ */ struct ovl_config { - char *lowerdir; char *upperdir; char *workdir; bool default_permissions; @@ -41,6 +40,7 @@ struct ovl_layer { int idx; /* One fsid per unique underlying sb (upper fsid == 0) */ int fsid; + char *name; }; /* @@ -101,7 +101,6 @@ struct ovl_fs { errseq_t errseq; }; - /* Number of lower layers, not including data-only layers */ static inline unsigned int ovl_numlowerlayer(struct ovl_fs *ofs) { diff --git a/fs/overlayfs/params.c b/fs/overlayfs/params.c new file mode 100644 index 000000000000..a1606af1613f --- /dev/null +++ b/fs/overlayfs/params.c @@ -0,0 +1,388 @@ +// SPDX-License-Identifier: GPL-2.0-only + +#include +#include +#include +#include +#include +#include +#include "overlayfs.h" + +static ssize_t ovl_parse_param_split_lowerdirs(char *str) +{ + ssize_t nr_layers = 1, nr_colons = 0; + char *s, *d; + + for (s = d = str;; s++, d++) { + if (*s == '\\') { + s++; + } else if (*s == ':') { + bool next_colon = (*(s + 1) == ':'); + + nr_colons++; + if (nr_colons == 2 && next_colon) { + pr_err("only single ':' or double '::' sequences of unescaped colons in lowerdir mount option allowed.\n"); + return -EINVAL; + } + /* count layers, not colons */ + if (!next_colon) + nr_layers++; + + *d = '\0'; + continue; + } + + *d = *s; + if (!*s) { + /* trailing colons */ + if (nr_colons) { + pr_err("unescaped trailing colons in lowerdir mount option.\n"); + return -EINVAL; + } + break; + } + nr_colons = 0; + } + + return nr_layers; +} + +static int ovl_mount_dir_noesc(const char *name, struct path *path) +{ + int err = -EINVAL; + + if (!*name) { + pr_err("empty lowerdir\n"); + goto out; + } + err = kern_path(name, LOOKUP_FOLLOW, path); + if (err) { + pr_err("failed to resolve '%s': %i\n", name, err); + goto out; + } + err = -EINVAL; + if (ovl_dentry_weird(path->dentry)) { + pr_err("filesystem on '%s' not supported\n", name); + goto out_put; + } + if (!d_is_dir(path->dentry)) { + pr_err("'%s' not a directory\n", name); + goto out_put; + } + return 0; + +out_put: + path_put_init(path); +out: + return err; +} + +static void ovl_unescape(char *s) +{ + char *d = s; + + for (;; s++, d++) { + if (*s == '\\') + s++; + *d = *s; + if (!*s) + break; + } +} + +static int ovl_mount_dir(const char *name, struct path *path) +{ + int err = -ENOMEM; + char *tmp = kstrdup(name, GFP_KERNEL); + + if (tmp) { + ovl_unescape(tmp); + err = ovl_mount_dir_noesc(tmp, path); + + if (!err && path->dentry->d_flags & DCACHE_OP_REAL) { + pr_err("filesystem on '%s' not supported as upperdir\n", + tmp); + path_put_init(path); + err = -EINVAL; + } + kfree(tmp); + } + return err; +} + +int ovl_parse_param_upperdir(const char *name, struct fs_context *fc, + bool workdir) +{ + int err; + struct ovl_fs *ofs = fc->s_fs_info; + struct ovl_config *config = &ofs->config; + struct ovl_fs_context *ctx = fc->fs_private; + struct path path; + char *dup; + + err = ovl_mount_dir(name, &path); + if (err) + return err; + + /* + * Check whether upper path is read-only here to report failures + * early. Don't forget to recheck when the superblock is created + * as the mount attributes could change. + */ + if (__mnt_is_readonly(path.mnt)) { + path_put(&path); + return -EINVAL; + } + + dup = kstrdup(name, GFP_KERNEL); + if (!dup) { + path_put(&path); + return -ENOMEM; + } + + if (workdir) { + kfree(config->workdir); + config->workdir = dup; + path_put(&ctx->work); + ctx->work = path; + } else { + kfree(config->upperdir); + config->upperdir = dup; + path_put(&ctx->upper); + ctx->upper = path; + } + return 0; +} + +void ovl_parse_param_drop_lowerdir(struct ovl_fs_context *ctx) +{ + for (size_t nr = 0; nr < ctx->nr; nr++) { + path_put(&ctx->lower[nr].path); + kfree(ctx->lower[nr].name); + ctx->lower[nr].name = NULL; + } + ctx->nr = 0; + ctx->nr_data = 0; +} + +/* + * Parse lowerdir= mount option: + * + * (1) lowerdir=/lower1:/lower2:/lower3::/data1::/data2 + * Set "/lower1", "/lower2", and "/lower3" as lower layers and + * "/data1" and "/data2" as data lower layers. Any existing lower + * layers are replaced. + * (2) lowerdir=:/lower4 + * Append "/lower4" to current stack of lower layers. This requires + * that there already is at least one lower layer configured. + * (3) lowerdir=::/lower5 + * Append data "/lower5" as data lower layer. This requires that + * there's at least one regular lower layer present. + */ +int ovl_parse_param_lowerdir(const char *name, struct fs_context *fc) +{ + int err; + struct ovl_fs_context *ctx = fc->fs_private; + struct ovl_fs_context_layer *l; + char *dup = NULL, *dup_iter; + ssize_t nr_lower = 0, nr = 0, nr_data = 0; + bool append = false, data_layer = false; + + /* + * Ensure we're backwards compatible with mount(2) + * by allowing relative paths. + */ + + /* drop all existing lower layers */ + if (!*name) { + ovl_parse_param_drop_lowerdir(ctx); + return 0; + } + + if (strncmp(name, "::", 2) == 0) { + /* + * This is a data layer. + * There must be at least one regular lower layer + * specified. + */ + if (ctx->nr == 0) { + pr_err("data lower layers without regular lower layers not allowed"); + return -EINVAL; + } + + /* Skip the leading "::". */ + name += 2; + data_layer = true; + /* + * A data layer is automatically an append as there + * must've been at least one regular lower layer. + */ + append = true; + } else if (*name == ':') { + /* + * This is a regular lower layer. + * If users want to append a layer enforce that they + * have already specified a first layer before. It's + * better to be strict. + */ + if (ctx->nr == 0) { + pr_err("cannot append layer if no previous layer has been specified"); + return -EINVAL; + } + + /* + * Once a sequence of data layers has started regular + * lower layers are forbidden. + */ + if (ctx->nr_data > 0) { + pr_err("regular lower layers cannot follow data lower layers"); + return -EINVAL; + } + + /* Skip the leading ":". */ + name++; + append = true; + } + + dup = kstrdup(name, GFP_KERNEL); + if (!dup) + return -ENOMEM; + + err = -EINVAL; + nr_lower = ovl_parse_param_split_lowerdirs(dup); + if (nr_lower < 0) + goto out_err; + + if ((nr_lower > OVL_MAX_STACK) || + (append && (size_add(ctx->nr, nr_lower) > OVL_MAX_STACK))) { + pr_err("too many lower directories, limit is %d\n", OVL_MAX_STACK); + goto out_err; + } + + if (!append) + ovl_parse_param_drop_lowerdir(ctx); + + /* + * (1) append + * + * We want nr <= nr_lower <= capacity We know nr > 0 and nr <= + * capacity. If nr == 0 this wouldn't be append. If nr + + * nr_lower is <= capacity then nr <= nr_lower <= capacity + * already holds. If nr + nr_lower exceeds capacity, we realloc. + * + * (2) replace + * + * Ensure we're backwards compatible with mount(2) which allows + * "lowerdir=/a:/b:/c,lowerdir=/d:/e:/f" causing the last + * specified lowerdir mount option to win. + * + * We want nr <= nr_lower <= capacity We know either (i) nr == 0 + * or (ii) nr > 0. We also know nr_lower > 0. The capacity + * could've been changed multiple times already so we only know + * nr <= capacity. If nr + nr_lower > capacity we realloc, + * otherwise nr <= nr_lower <= capacity holds already. + */ + nr_lower += ctx->nr; + if (nr_lower > ctx->capacity) { + err = -ENOMEM; + l = krealloc_array(ctx->lower, nr_lower, sizeof(*ctx->lower), + GFP_KERNEL_ACCOUNT); + if (!l) + goto out_err; + + ctx->lower = l; + ctx->capacity = nr_lower; + } + + /* + * (3) By (1) and (2) we know nr <= nr_lower <= capacity. + * (4) If ctx->nr == 0 => replace + * We have verified above that the lowerdir mount option + * isn't an append, i.e., the lowerdir mount option + * doesn't start with ":" or "::". + * (4.1) The lowerdir mount options only contains regular lower + * layers ":". + * => Nothing to verify. + * (4.2) The lowerdir mount options contains regular ":" and + * data "::" layers. + * => We need to verify that data lower layers "::" aren't + * followed by regular ":" lower layers + * (5) If ctx->nr > 0 => append + * We know that there's at least one regular layer + * otherwise we would've failed when parsing the previous + * lowerdir mount option. + * (5.1) The lowerdir mount option is a regular layer ":" append + * => We need to verify that no data layers have been + * specified before. + * (5.2) The lowerdir mount option is a data layer "::" append + * We know that there's at least one regular layer or + * other data layers. => There's nothing to verify. + */ + dup_iter = dup; + for (nr = ctx->nr; nr < nr_lower; nr++) { + l = &ctx->lower[nr]; + + err = ovl_mount_dir_noesc(dup_iter, &l->path); + if (err) + goto out_put; + + err = -ENOMEM; + l->name = kstrdup(dup_iter, GFP_KERNEL_ACCOUNT); + if (!l->name) + goto out_put; + + if (data_layer) + nr_data++; + + /* Calling strchr() again would overrun. */ + if ((nr + 1) == nr_lower) + break; + + err = -EINVAL; + dup_iter = strchr(dup_iter, '\0') + 1; + if (*dup_iter) { + /* + * This is a regular layer so we require that + * there are no data layers. + */ + if ((ctx->nr_data + nr_data) > 0) { + pr_err("regular lower layers cannot follow data lower layers"); + goto out_put; + } + + data_layer = false; + continue; + } + + /* This is a data lower layer. */ + data_layer = true; + dup_iter++; + } + ctx->nr = nr_lower; + ctx->nr_data += nr_data; + kfree(dup); + return 0; + +out_put: + /* + * We know nr >= ctx->nr < nr_lower. If we failed somewhere + * we want to undo until nr == ctx->nr. This is correct for + * both ctx->nr == 0 and ctx->nr > 0. + */ + for (; nr >= ctx->nr; nr--) { + l = &ctx->lower[nr]; + kfree(l->name); + l->name = NULL; + path_put(&l->path); + + /* don't overflow */ + if (nr == 0) + break; + } + +out_err: + kfree(dup); + + /* Intentionally don't realloc to a smaller size. */ + return err; +} diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 3392dc5d2082..b73b14c52961 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -27,8 +27,6 @@ MODULE_LICENSE("GPL"); struct ovl_dir_cache; -#define OVL_MAX_STACK 500 - static bool ovl_redirect_dir_def = IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_DIR); module_param_named(redirect_dir, ovl_redirect_dir_def, bool, 0644); MODULE_PARM_DESC(redirect_dir, @@ -109,8 +107,11 @@ static const char *ovl_redirect_mode(struct ovl_config *config) return ovl_parameter_redirect_dir[config->redirect_mode].name; } +#define fsparam_string_empty(NAME, OPT) \ + __fsparam(fs_param_is_string, NAME, OPT, fs_param_can_be_empty, NULL) + static const struct fs_parameter_spec ovl_parameter_spec[] = { - fsparam_string("lowerdir", Opt_lowerdir), + fsparam_string_empty("lowerdir", Opt_lowerdir), fsparam_string("upperdir", Opt_upperdir), fsparam_string("workdir", Opt_workdir), fsparam_flag("default_permissions", Opt_default_permissions), @@ -125,15 +126,15 @@ static const struct fs_parameter_spec ovl_parameter_spec[] = { {} }; +/* + * These options imply different behavior when they are explicitly + * specified than when they are left in their default state. + */ #define OVL_METACOPY_SET BIT(0) #define OVL_REDIRECT_SET BIT(1) #define OVL_NFS_EXPORT_SET BIT(2) #define OVL_INDEX_SET BIT(3) -struct ovl_fs_context { - u8 set; -}; - static struct dentry *ovl_d_real(struct dentry *dentry, const struct inode *inode) { @@ -308,6 +309,7 @@ static void ovl_free_fs(struct ovl_fs *ofs) for (i = 0; i < ofs->numlayer; i++) { iput(ofs->layers[i].trap); mounts[i] = ofs->layers[i].mnt; + kfree(ofs->layers[i].name); } kern_unmount_array(mounts, ofs->numlayer); kfree(ofs->layers); @@ -315,7 +317,6 @@ static void ovl_free_fs(struct ovl_fs *ofs) free_anon_bdev(ofs->fs[i].pseudo_dev); kfree(ofs->fs); - kfree(ofs->config.lowerdir); kfree(ofs->config.upperdir); kfree(ofs->config.workdir); if (ofs->creator_cred) @@ -433,8 +434,17 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry) struct super_block *sb = dentry->d_sb; struct ovl_fs *ofs = sb->s_fs_info; const char *redirect_mode; - - seq_show_option(m, "lowerdir", ofs->config.lowerdir); + size_t nr, nr_merged_lower = ofs->numlayer - ofs->numdatalayer; + const struct ovl_layer *data_layers = &ofs->layers[nr_merged_lower]; + + /* ofs->layers[0] is the upper layer */ + seq_printf(m, ",lowerdir=%s", ofs->layers[1].name); + /* dump regular lower layers */ + for (nr = 2; nr < nr_merged_lower; nr++) + seq_printf(m, ":%s", ofs->layers[nr].name); + /* dump data lower layers */ + for (nr = 0; nr < ofs->numdatalayer; nr++) + seq_printf(m, "::%s", data_layers[nr].name); if (ofs->config.upperdir) { seq_show_option(m, "upperdir", ofs->config.upperdir); seq_show_option(m, "workdir", ofs->config.workdir); @@ -509,6 +519,11 @@ static int ovl_fs_params_verify(const struct ovl_fs_context *ctx, bool nfs_export_opt = ctx->set & OVL_NFS_EXPORT_SET; bool index_opt = ctx->set & OVL_INDEX_SET; + if (ctx->nr_data > 0 && !config->metacopy) { + pr_err("lower data-only dirs require metacopy support.\n"); + return -EINVAL; + } + /* Workdir/index are useless in non-upper mount */ if (!config->upperdir) { if (config->workdir) { @@ -723,69 +738,6 @@ static struct dentry *ovl_workdir_create(struct ovl_fs *ofs, goto out_unlock; } -static void ovl_unescape(char *s) -{ - char *d = s; - - for (;; s++, d++) { - if (*s == '\\') - s++; - *d = *s; - if (!*s) - break; - } -} - -static int ovl_mount_dir_noesc(const char *name, struct path *path) -{ - int err = -EINVAL; - - if (!*name) { - pr_err("empty lowerdir\n"); - goto out; - } - err = kern_path(name, LOOKUP_FOLLOW, path); - if (err) { - pr_err("failed to resolve '%s': %i\n", name, err); - goto out; - } - err = -EINVAL; - if (ovl_dentry_weird(path->dentry)) { - pr_err("filesystem on '%s' not supported\n", name); - goto out_put; - } - if (!d_is_dir(path->dentry)) { - pr_err("'%s' not a directory\n", name); - goto out_put; - } - return 0; - -out_put: - path_put_init(path); -out: - return err; -} - -static int ovl_mount_dir(const char *name, struct path *path) -{ - int err = -ENOMEM; - char *tmp = kstrdup(name, GFP_KERNEL); - - if (tmp) { - ovl_unescape(tmp); - err = ovl_mount_dir_noesc(tmp, path); - - if (!err && path->dentry->d_flags & DCACHE_OP_REAL) { - pr_err("filesystem on '%s' not supported as upperdir\n", - tmp); - path_put_init(path); - err = -EINVAL; - } - kfree(tmp); - } - return err; -} - static int ovl_check_namelen(const struct path *path, struct ovl_fs *ofs, const char *name) { @@ -806,10 +758,6 @@ static int ovl_lower_dir(const char *name, struct path *path, int fh_type; int err; - err = ovl_mount_dir_noesc(name, path); - if (err) - return err; - err = ovl_check_namelen(path, ofs, name); if (err) return err; @@ -858,26 +806,6 @@ static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir) return ok; } -static unsigned int ovl_split_lowerdirs(char *str) -{ - unsigned int ctr = 1; - char *s, *d; - - for (s = d = str;; s++, d++) { - if (*s == '\\') { - s++; - } else if (*s == ':') { - *d = '\0'; - ctr++; - continue; - } - *d = *s; - if (!*s) - break; - } - return ctr; -} - static int ovl_own_xattr_get(const struct xattr_handler *handler, struct dentry *dentry, struct inode *inode, const char *name, void *buffer, size_t size) @@ -978,15 +906,12 @@ static int ovl_report_in_use(struct ovl_fs *ofs, const char *name) } static int ovl_get_upper(struct super_block *sb, struct ovl_fs *ofs, - struct ovl_layer *upper_layer, struct path *upperpath) + struct ovl_layer *upper_layer, + const struct path *upperpath) { struct vfsmount *upper_mnt; int err; - err = ovl_mount_dir(ofs->config.upperdir, upperpath); - if (err) - goto out; - /* Upperdir path should not be r/o */ if (__mnt_is_readonly(upperpath->mnt)) { pr_err("upper fs is r/o, try multi-lower layers mount\n"); @@ -1016,6 +941,11 @@ static int ovl_get_upper(struct super_block *sb, struct ovl_fs *ofs, upper_layer->idx = 0; upper_layer->fsid = 0; + err = -ENOMEM; + upper_layer->name = kstrdup(ofs->config.upperdir, GFP_KERNEL); + if (!upper_layer->name) + goto out; + /* * Inherit SB_NOSEC flag from upperdir. * @@ -1273,46 +1203,37 @@ static int ovl_make_workdir(struct super_block *sb, struct ovl_fs *ofs, } static int ovl_get_workdir(struct super_block *sb, struct ovl_fs *ofs, - const struct path *upperpath) + const struct path *upperpath, + const struct path *workpath) { int err; - struct path workpath = { }; - - err = ovl_mount_dir(ofs->config.workdir, &workpath); - if (err) - goto out; err = -EINVAL; - if (upperpath->mnt != workpath.mnt) { + if (upperpath->mnt != workpath->mnt) { pr_err("workdir and upperdir must reside under the same mount\n"); - goto out; + return err; } - if (!ovl_workdir_ok(workpath.dentry, upperpath->dentry)) { + if (!ovl_workdir_ok(workpath->dentry, upperpath->dentry)) { pr_err("workdir and upperdir must be separate subtrees\n"); - goto out; + return err; } - ofs->workbasedir = dget(workpath.dentry); + ofs->workbasedir = dget(workpath->dentry); if (ovl_inuse_trylock(ofs->workbasedir)) { ofs->workdir_locked = true; } else { err = ovl_report_in_use(ofs, "workdir"); if (err) - goto out; + return err; } err = ovl_setup_trap(sb, ofs->workbasedir, &ofs->workbasedir_trap, "workdir"); if (err) - goto out; - - err = ovl_make_workdir(sb, ofs, &workpath); - -out: - path_put(&workpath); + return err; - return err; + return ovl_make_workdir(sb, ofs, workpath); } static int ovl_get_indexdir(struct super_block *sb, struct ovl_fs *ofs, @@ -1476,13 +1397,13 @@ static int ovl_get_data_fsid(struct ovl_fs *ofs) static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs, - struct path *stack, unsigned int numlower, - struct ovl_layer *layers) + struct ovl_fs_context *ctx, struct ovl_layer *layers) { int err; unsigned int i; + size_t nr_merged_lower; - ofs->fs = kcalloc(numlower + 2, sizeof(struct ovl_sb), GFP_KERNEL); + ofs->fs = kcalloc(ctx->nr + 2, sizeof(struct ovl_sb), GFP_KERNEL); if (ofs->fs == NULL) return -ENOMEM; @@ -1509,13 +1430,15 @@ static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs, ofs->fs[0].is_lower = false; } - for (i = 0; i < numlower; i++) { + nr_merged_lower = ctx->nr - ctx->nr_data; + for (i = 0; i < ctx->nr; i++) { + struct ovl_fs_context_layer *l = &ctx->lower[i]; struct vfsmount *mnt; struct inode *trap; int fsid; - if (i < numlower - ofs->numdatalayer) - fsid = ovl_get_fsid(ofs, &stack[i]); + if (i < nr_merged_lower) + fsid = ovl_get_fsid(ofs, &l->path); else fsid = ovl_get_data_fsid(ofs); if (fsid < 0) @@ -1528,11 +1451,11 @@ static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs, * the upperdir/workdir is in fact in-use by our * upperdir/workdir. */ - err = ovl_setup_trap(sb, stack[i].dentry, &trap, "lowerdir"); + err = ovl_setup_trap(sb, l->path.dentry, &trap, "lowerdir"); if (err) return err; - if (ovl_is_inuse(stack[i].dentry)) { + if (ovl_is_inuse(l->path.dentry)) { err = ovl_report_in_use(ofs, "lowerdir"); if (err) { iput(trap); @@ -1540,7 +1463,7 @@ static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs, } } - mnt = clone_private_mount(&stack[i]); + mnt = clone_private_mount(&l->path); err = PTR_ERR(mnt); if (IS_ERR(mnt)) { pr_err("failed to clone lowerpath\n"); @@ -1559,6 +1482,8 @@ static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs, layers[ofs->numlayer].idx = ofs->numlayer; layers[ofs->numlayer].fsid = fsid; layers[ofs->numlayer].fs = &ofs->fs[fsid]; + layers[ofs->numlayer].name = l->name; + l->name = NULL; ofs->numlayer++; ofs->fs[fsid].is_lower = true; } @@ -1599,104 +1524,59 @@ static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs, } static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb, - const char *lower, unsigned int numlower, - struct ovl_fs *ofs, struct ovl_layer *layers) + struct ovl_fs_context *ctx, + struct ovl_fs *ofs, + struct ovl_layer *layers) { int err; - struct path *stack = NULL; - struct ovl_path *lowerstack; - unsigned int numlowerdata = 0; unsigned int i; + size_t nr_merged_lower; struct ovl_entry *oe; + struct ovl_path *lowerstack; - if (!ofs->config.upperdir && numlower == 1) { + struct ovl_fs_context_layer *l; + + if (!ofs->config.upperdir && ctx->nr == 1) { pr_err("at least 2 lowerdir are needed while upperdir nonexistent\n"); return ERR_PTR(-EINVAL); } - stack = kcalloc(numlower, sizeof(struct path), GFP_KERNEL); - if (!stack) - return ERR_PTR(-ENOMEM); + err = -EINVAL; + for (i = 0; i < ctx->nr; i++) { + l = &ctx->lower[i]; - for (i = 0; i < numlower;) { - err = ovl_lower_dir(lower, &stack[i], ofs, &sb->s_stack_depth); + err = ovl_lower_dir(l->name, &l->path, ofs, &sb->s_stack_depth); if (err) - goto out_err; - - lower = strchr(lower, '\0') + 1; - - i++; - if (i == numlower) - break; - - err = -EINVAL; - /* - * Empty lower layer path could mean :: separator that indicates - * a data-only lower data. - * Several data-only layers are allowed, but they all need to be - * at the bottom of the stack. - */ - if (*lower) { - /* normal lower dir */ - if (numlowerdata) { - pr_err("lower data-only dirs must be at the bottom of the stack.\n"); - goto out_err; - } - } else { - /* data-only lower dir */ - if (!ofs->config.metacopy) { - pr_err("lower data-only dirs require metacopy support.\n"); - goto out_err; - } - if (i == numlower - 1) { - pr_err("lowerdir argument must not end with double colon.\n"); - goto out_err; - } - lower++; - numlower--; - numlowerdata++; - } - } - - if (numlowerdata) { - ofs->numdatalayer = numlowerdata; - pr_info("using the lowest %d of %d lowerdirs as data layers\n", - numlowerdata, numlower); + return ERR_PTR(err); } err = -EINVAL; sb->s_stack_depth++; if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) { pr_err("maximum fs stacking depth exceeded\n"); - goto out_err; + return ERR_PTR(err); } - err = ovl_get_layers(sb, ofs, stack, numlower, layers); + err = ovl_get_layers(sb, ofs, ctx, layers); if (err) - goto out_err; + return ERR_PTR(err); err = -ENOMEM; /* Data-only layers are not merged in root directory */ - oe = ovl_alloc_entry(numlower - numlowerdata); + nr_merged_lower = ctx->nr - ctx->nr_data; + oe = ovl_alloc_entry(nr_merged_lower); if (!oe) - goto out_err; + return ERR_PTR(err); lowerstack = ovl_lowerstack(oe); - for (i = 0; i < numlower - numlowerdata; i++) { - lowerstack[i].dentry = dget(stack[i].dentry); - lowerstack[i].layer = &ofs->layers[i+1]; + for (i = 0; i < nr_merged_lower; i++) { + l = &ctx->lower[i]; + lowerstack[i].dentry = dget(l->path.dentry); + lowerstack[i].layer = &ofs->layers[i + 1]; } - -out: - for (i = 0; i < numlower; i++) - path_put(&stack[i]); - kfree(stack); + ofs->numdatalayer = ctx->nr_data; return oe; - -out_err: - oe = ERR_PTR(err); - goto out; } /* @@ -1804,6 +1684,12 @@ static struct dentry *ovl_get_root(struct super_block *sb, ovl_set_upperdata(d_inode(root)); ovl_inode_init(d_inode(root), &oip, ino, fsid); ovl_dentry_init_flags(root, upperdentry, oe, DCACHE_OP_WEAK_REVALIDATE); + /* + * We're going to put upper path when we call + * fs_context_operations->free() take an additional + * reference so we can just call path_put(). + */ + dget(upperdentry); return root; } @@ -1815,7 +1701,6 @@ static int ovl_parse_param(struct fs_context *fc, struct fs_parameter *param) struct ovl_fs *ofs = fc->s_fs_info; struct ovl_config *config = &ofs->config; struct ovl_fs_context *ctx = fc->fs_private; - char *dup; int opt; /* @@ -1832,34 +1717,13 @@ static int ovl_parse_param(struct fs_context *fc, struct fs_parameter *param) switch (opt) { case Opt_lowerdir: - dup = kstrdup(param->string, GFP_KERNEL); - if (!dup) { - err = -ENOMEM; - break; - } - - kfree(config->lowerdir); - config->lowerdir = dup; + err = ovl_parse_param_lowerdir(param->string, fc); break; case Opt_upperdir: - dup = kstrdup(param->string, GFP_KERNEL); - if (!dup) { - err = -ENOMEM; - break; - } - - kfree(config->upperdir); - config->upperdir = dup; - break; + fallthrough; case Opt_workdir: - dup = kstrdup(param->string, GFP_KERNEL); - if (!dup) { - err = -ENOMEM; - break; - } - - kfree(config->workdir); - config->workdir = dup; + err = ovl_parse_param_upperdir(param->string, fc, + (Opt_workdir == opt)); break; case Opt_default_permissions: config->default_permissions = true; @@ -1927,13 +1791,10 @@ static int ovl_fill_super(struct super_block *sb, struct fs_context *fc) { struct ovl_fs *ofs = sb->s_fs_info; struct ovl_fs_context *ctx = fc->fs_private; - struct path upperpath = {}; struct dentry *root_dentry; struct ovl_entry *oe; struct ovl_layer *layers; struct cred *cred; - char *splitlower = NULL; - unsigned int numlower; int err; err = -EIO; @@ -1952,28 +1813,20 @@ static int ovl_fill_super(struct super_block *sb, struct fs_context *fc) if (err) goto out_err; + /* + * Check ctx->nr instead of ofs->config.lowerdir since we're + * going to set ofs->config.lowerdir here after we know that the + * user specified all layers. + */ err = -EINVAL; - if (!ofs->config.lowerdir) { + if (ctx->nr == 0) { if (fc->sb_flags & SB_SILENT) pr_err("missing 'lowerdir'\n"); goto out_err; } err = -ENOMEM; - splitlower = kstrdup(ofs->config.lowerdir, GFP_KERNEL); - if (!splitlower) - goto out_err; - - err = -EINVAL; - numlower = ovl_split_lowerdirs(splitlower); - if (numlower > OVL_MAX_STACK) { - pr_err("too many lower directories, limit is %d\n", - OVL_MAX_STACK); - goto out_err; - } - - err = -ENOMEM; - layers = kcalloc(numlower + 1, sizeof(struct ovl_layer), GFP_KERNEL); + layers = kcalloc(ctx->nr + 1, sizeof(struct ovl_layer), GFP_KERNEL); if (!layers) goto out_err; @@ -2005,7 +1858,7 @@ static int ovl_fill_super(struct super_block *sb, struct fs_context *fc) goto out_err; } - err = ovl_get_upper(sb, ofs, &layers[0], &upperpath); + err = ovl_get_upper(sb, ofs, &layers[0], &ctx->upper); if (err) goto out_err; @@ -2019,7 +1872,7 @@ static int ovl_fill_super(struct super_block *sb, struct fs_context *fc) } } - err = ovl_get_workdir(sb, ofs, &upperpath); + err = ovl_get_workdir(sb, ofs, &ctx->upper, &ctx->work); if (err) goto out_err; @@ -2029,7 +1882,7 @@ static int ovl_fill_super(struct super_block *sb, struct fs_context *fc) sb->s_stack_depth = upper_sb->s_stack_depth; sb->s_time_gran = upper_sb->s_time_gran; } - oe = ovl_get_lowerstack(sb, splitlower, numlower, ofs, layers); + oe = ovl_get_lowerstack(sb, ctx, ofs, layers); err = PTR_ERR(oe); if (IS_ERR(oe)) goto out_err; @@ -2044,7 +1897,7 @@ static int ovl_fill_super(struct super_block *sb, struct fs_context *fc) } if (!ovl_force_readonly(ofs) && ofs->config.index) { - err = ovl_get_indexdir(sb, ofs, oe, &upperpath); + err = ovl_get_indexdir(sb, ofs, oe, &ctx->upper); if (err) goto out_free_oe; @@ -2085,13 +1938,10 @@ static int ovl_fill_super(struct super_block *sb, struct fs_context *fc) sb->s_iflags |= SB_I_SKIP_SYNC; err = -ENOMEM; - root_dentry = ovl_get_root(sb, upperpath.dentry, oe); + root_dentry = ovl_get_root(sb, ctx->upper.dentry, oe); if (!root_dentry) goto out_free_oe; - mntput(upperpath.mnt); - kfree(splitlower); - sb->s_root = root_dentry; return 0; @@ -2109,6 +1959,10 @@ static int ovl_get_tree(struct fs_context *fc) static inline void ovl_fs_context_free(struct ovl_fs_context *ctx) { + ovl_parse_param_drop_lowerdir(ctx); + path_put(&ctx->upper); + path_put(&ctx->work); + kfree(ctx->lower); kfree(ctx); } @@ -2153,11 +2007,18 @@ static int ovl_init_fs_context(struct fs_context *fc) if (!ctx) return -ENOMEM; + /* + * By default we allocate for three lower layers. It's likely + * that it'll cover most users. + */ + ctx->lower = kmalloc_array(3, sizeof(*ctx->lower), GFP_KERNEL_ACCOUNT); + if (!ctx->lower) + goto out_err; + ctx->capacity = 3; + ofs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL); - if (!ofs) { - ovl_fs_context_free(ctx); - return -ENOMEM; - } + if (!ofs) + goto out_err; if (strcmp(ovl_redirect_mode_def(), "on") == 0) ofs->config.redirect_mode = OVL_REDIRECT_DIR_ON; @@ -2174,6 +2035,11 @@ static int ovl_init_fs_context(struct fs_context *fc) fc->fs_private = ctx; fc->ops = &ovl_context_ops; return 0; + +out_err: + ovl_fs_context_free(ctx); + return -ENOMEM; + } static struct file_system_type ovl_fs_type = {