From patchwork Thu Sep 7 17:01:46 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jiao Zhou X-Patchwork-Id: 720699 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 B2953EC8743 for ; Thu, 7 Sep 2023 17:03:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233766AbjIGRDN (ORCPT ); Thu, 7 Sep 2023 13:03:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44000 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238086AbjIGRDM (ORCPT ); Thu, 7 Sep 2023 13:03:12 -0400 Received: from mail-yw1-x1149.google.com (mail-yw1-x1149.google.com [IPv6:2607:f8b0:4864:20::1149]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C44521BF for ; Thu, 7 Sep 2023 10:02:45 -0700 (PDT) Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-59b50b45481so3407727b3.1 for ; Thu, 07 Sep 2023 10:02:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1694106108; x=1694710908; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=T/WqaSkwJ/wvgxciY6xG5yXoKMXUwDNF7ZMhyjAl3dg=; b=Zoy6/8frpbrylGHHAyT4djGKi0qnFo0jUZd2+XPWBD6z1XIyolDLfvBNphbUkBNANE it/PHT39kDqyUKMwB68VeEhJwCGAenL62FVbSK6LxTMrhA+X4DdkD2ZuXInRW2Aa2Lpl QQDoo+9uB26925ngpVkriw93BfD84r/jud5y27t1IPCacek0N5V31eS1T1PifUfyBiy0 9qsVO3v9/ey4x1rhxyZzbJ7p9uOqNQiT8gXjmyAPzQu9isDDZ4dPWYQukNAluUqSnVur 86bFn5cYF87NQ5TPtWLCZfT5w4lk1UoIvaMhnKldED1n8rDHKY1qXCfemfVvpm2FD38v lEUQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1694106108; x=1694710908; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=T/WqaSkwJ/wvgxciY6xG5yXoKMXUwDNF7ZMhyjAl3dg=; b=SHwxAAjPf1exB0X/8ySBIckelb6gLS9Q4EhZQ1zixU/DkMxlPZSSMj28MEsL870m4a 3QOx0tKdI9mDDbSlOrskmFY0JCoh3VWHQdB3iPgCZ/QrF8yuR4Ax2tyK2HfbQoGQdDVP e5PFc1f6hJ0rRj3+WVFfWiHIfyPRC+A2eEg62K+mF4SYeMVlu+CNJOodqavZGL+JxAzm DqOWTyKlSjVEBJ74BoLRlvoZkA6Wb2NxfWkmf5KGh+KXzB/O6ndoDibtxdAiasSC1jo/ tjy1bvKbpTrJz1/zvM3WPbpqKsip5rAQS1ObaA7TeClCnblMt8h61dzdroA4jqnzH/8I z4wA== X-Gm-Message-State: AOJu0YwJJSl/jdfVb9TrOEfhQKcU6FCVNf8h/r56RkmriGRigfy6fuEC CVL1q6pqXf0RQTd6Wes+gQsKNyu1tmcvRg== X-Google-Smtp-Source: AGHT+IE2Uit7N3S9SR5qftU0oDHFbdy+GAjL3k4RaTzFuKFUAbWpfVTvea/hgEAbk4PmwL4jjFvknP/BCQlIsg== X-Received: from jiao.c.googlers.com ([fda3:e722:ac3:cc00:2b:7d90:c0a8:10f3]) (user=jiaozhou job=sendgmr) by 2002:a81:b708:0:b0:573:8316:8d04 with SMTP id v8-20020a81b708000000b0057383168d04mr5076ywh.4.1694106108565; Thu, 07 Sep 2023 10:01:48 -0700 (PDT) Date: Thu, 7 Sep 2023 17:01:46 +0000 Mime-Version: 1.0 X-Mailer: git-send-email 2.42.0.283.g2d96d420d3-goog Message-ID: <20230907170146.1055954-1-jiaozhou@google.com> Subject: [PATCH v5] efivarfs: Add uid/gid mount options From: Jiao Zhou To: Linux FS Development Cc: Jiao Zhou , Ard Biesheuvel , Jeremy Kerr , linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, mjg59@srcf.ucam.org, Matthew Garrett Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org Allow UEFI variables to be modified by non-root processes in order to run sandboxed code. This doesn't change the behavior of mounting efivarfs unless uid/gid are specified; by default both are set to root. Signed-off-by: Jiao Zhou Acked-by: Matthew Garrett --- Changelog since v1: - Add missing sentinel entry in fs_parameter_spec[] array. - Fix a NULL pointer dereference. Changelog since v2: - Format the patch description. Changelog since v3: - Add gid and uid check to make sure that ids are valid. - Drop the indentation for one block. - Use sizeof(*sfi) to allocate memory to avoids future problems if sfi ever changes type. Changelog since v4: - Fix the use of sizeof. --- fs/efivarfs/inode.c | 4 +++ fs/efivarfs/internal.h | 9 +++++ fs/efivarfs/super.c | 74 ++++++++++++++++++++++++++++++++++++++++-- 3 files changed, 84 insertions(+), 3 deletions(-) diff --git a/fs/efivarfs/inode.c b/fs/efivarfs/inode.c index db9231f0e77b..06dfc73fda04 100644 --- a/fs/efivarfs/inode.c +++ b/fs/efivarfs/inode.c @@ -20,9 +20,13 @@ struct inode *efivarfs_get_inode(struct super_block *sb, const struct inode *dir, int mode, dev_t dev, bool is_removable) { + struct efivarfs_fs_info *fsi = sb->s_fs_info; struct inode *inode = new_inode(sb); + struct efivarfs_mount_opts *opts = &fsi->mount_opts; if (inode) { + inode->i_uid = opts->uid; + inode->i_gid = opts->gid; inode->i_ino = get_next_ino(); inode->i_mode = mode; inode->i_atime = inode->i_mtime = inode_set_ctime_current(inode); diff --git a/fs/efivarfs/internal.h b/fs/efivarfs/internal.h index 8ebf3a6a8aa2..c66647f5c0bd 100644 --- a/fs/efivarfs/internal.h +++ b/fs/efivarfs/internal.h @@ -9,6 +9,15 @@ #include #include +struct efivarfs_mount_opts { + kuid_t uid; + kgid_t gid; +}; + +struct efivarfs_fs_info { + struct efivarfs_mount_opts mount_opts; +}; + struct efi_variable { efi_char16_t VariableName[EFI_VAR_NAME_LEN/sizeof(efi_char16_t)]; efi_guid_t VendorGuid; diff --git a/fs/efivarfs/super.c b/fs/efivarfs/super.c index e028fafa04f3..ba14736ebae0 100644 --- a/fs/efivarfs/super.c +++ b/fs/efivarfs/super.c @@ -8,6 +8,7 @@ #include #include #include +#include #include #include #include @@ -24,6 +25,21 @@ static void efivarfs_evict_inode(struct inode *inode) clear_inode(inode); } +static int efivarfs_show_options(struct seq_file *m, struct dentry *root) +{ + struct super_block *sb = root->d_sb; + struct efivarfs_fs_info *sbi = sb->s_fs_info; + struct efivarfs_mount_opts *opts = &sbi->mount_opts; + + if (!uid_eq(opts->uid, GLOBAL_ROOT_UID)) + seq_printf(m, ",uid=%u", + from_kuid_munged(&init_user_ns, opts->uid)); + if (!gid_eq(opts->gid, GLOBAL_ROOT_GID)) + seq_printf(m, ",gid=%u", + from_kgid_munged(&init_user_ns, opts->gid)); + return 0; +} + static int efivarfs_statfs(struct dentry *dentry, struct kstatfs *buf) { const u32 attr = EFI_VARIABLE_NON_VOLATILE | @@ -64,6 +80,7 @@ static const struct super_operations efivarfs_ops = { .statfs = efivarfs_statfs, .drop_inode = generic_delete_inode, .evict_inode = efivarfs_evict_inode, + .show_options = efivarfs_show_options, }; /* @@ -225,6 +242,45 @@ static int efivarfs_destroy(struct efivar_entry *entry, void *data) return 0; } +enum { + Opt_uid, Opt_gid, +}; + +static const struct fs_parameter_spec efivarfs_parameters[] = { + fsparam_u32("uid", Opt_uid), + fsparam_u32("gid", Opt_gid), + {}, +}; + +static int efivarfs_parse_param(struct fs_context *fc, struct fs_parameter *param) +{ + struct efivarfs_fs_info *sbi = fc->s_fs_info; + struct efivarfs_mount_opts *opts = &sbi->mount_opts; + struct fs_parse_result result; + int opt; + + opt = fs_parse(fc, efivarfs_parameters, param, &result); + if (opt < 0) + return opt; + + switch (opt) { + case Opt_uid: + opts->uid = make_kuid(current_user_ns(), result.uint_32); + if (!uid_valid(opts->uid)) + return -EINVAL; + break; + case Opt_gid: + opts->gid = make_kgid(current_user_ns(), result.uint_32); + if (!gid_valid(opts->gid)) + return -EINVAL; + break; + default: + return -EINVAL; + } + + return 0; +} + static int efivarfs_fill_super(struct super_block *sb, struct fs_context *fc) { struct inode *inode = NULL; @@ -270,11 +326,22 @@ static int efivarfs_get_tree(struct fs_context *fc) } static const struct fs_context_operations efivarfs_context_ops = { - .get_tree = efivarfs_get_tree, + .get_tree = efivarfs_get_tree, + .parse_param = efivarfs_parse_param, }; static int efivarfs_init_fs_context(struct fs_context *fc) { + struct efivarfs_fs_info *sfi; + + sfi = kzalloc(sizeof(*sfi), GFP_KERNEL); + if (!sfi) + return -ENOMEM; + + sfi->mount_opts.uid = GLOBAL_ROOT_UID; + sfi->mount_opts.gid = GLOBAL_ROOT_GID; + + fc->s_fs_info = sfi; fc->ops = &efivarfs_context_ops; return 0; } @@ -291,10 +358,11 @@ static void efivarfs_kill_sb(struct super_block *sb) } static struct file_system_type efivarfs_type = { - .owner = THIS_MODULE, - .name = "efivarfs", + .owner = THIS_MODULE, + .name = "efivarfs", .init_fs_context = efivarfs_init_fs_context, .kill_sb = efivarfs_kill_sb, + .parameters = efivarfs_parameters, }; static __init int efivarfs_init(void)