From nobody Fri Dec 19 04:52:17 2025 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 AF73EEC8743 for ; Thu, 7 Sep 2023 17:20:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242984AbjIGRUi (ORCPT ); Thu, 7 Sep 2023 13:20:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38240 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243144AbjIGRUa (ORCPT ); Thu, 7 Sep 2023 13:20:30 -0400 Received: from mail-qk1-x74a.google.com (mail-qk1-x74a.google.com [IPv6:2607:f8b0:4864:20::74a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 113DA2685 for ; Thu, 7 Sep 2023 10:20:06 -0700 (PDT) Received: by mail-qk1-x74a.google.com with SMTP id af79cd13be357-770538a2946so135159285a.0 for ; Thu, 07 Sep 2023 10:20:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1694107139; x=1694711939; 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=sKfVXSAO8+tVFs/JKnSUF10ddieWjad38VpvF1F9+l0umnexb2P9PI2299tUhZApoV yks2/MthWEqtTlWWif9ApuATuYSpXAyxEPdzaDrYrB1vSl+7OEQQff04C6G+9ZHoWn0S sLMJ+e7uHNSnvxcis43PC8Oqs25Nef4bgRqVqZs3Hmk230FDaEy4qfulNoY5xjOtOwpW crx9mGCvKZTY71rc2T+xr+MENLNtXhFjj2D+WpmVO44f3AsicKwynJnoclmlrodpJZS8 NbTVA/VtpGgKw9nNUlV1HA1FPNCdFFV8zz2TP/3jGgttDIFUFtCgP9OApe2Ds6R0mVVe VKeQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1694107139; x=1694711939; 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=B11l0VflIRfNbis/UzgxWa4Gh3/aM3AHoFCrYQPRWqNelqVHPqPiNdavtqTkWkJw0m 9UU6TthJxmiTsCCC8iM+HTbcUQWlSQL8BkYMIOtL9FoOG9yLSV/VDwEZv1+NlgFI0qFO Unk0bBJ5P4Ktvgn40Gux/GRpNbTW20Si/QpdUZMIajhdU3zITDH7jWn/DlVRLhttDbWH vXrjI7IxTeAFclMZ8H1aMAEMGW3R37wLOtWMOkBzN4S0xZGnc7FGO4Z75HIhGYk9K2Y6 /HQ+SJC2jloacxOJWMtlGQwlfZlPk7Rmmsfk/zYjTqnyA2SrTtQfKbP2yojUltVUGvLT 44Yg== X-Gm-Message-State: AOJu0Yz7LSp1dQLJgV+6BencW+lpvcCpJs3jLiALK4FCb85DuVHt+0AU /fpKgnyl1BdXMUekC0plkYqcOwSovKNEtA== 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-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Allow UEFI variables to be modified by non-root processes in order to run sandboxed code. This doesn't change the behavior=20 of mounting efivarfs unless uid/gid are specified;=20 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 =3D sb->s_fs_info; struct inode *inode =3D new_inode(sb); + struct efivarfs_mount_opts *opts =3D &fsi->mount_opts; =20 if (inode) { + inode->i_uid =3D opts->uid; + inode->i_gid =3D opts->gid; inode->i_ino =3D get_next_ino(); inode->i_mode =3D mode; inode->i_atime =3D inode->i_mtime =3D 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 =20 +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); } =20 +static int efivarfs_show_options(struct seq_file *m, struct dentry *root) +{ + struct super_block *sb =3D root->d_sb; + struct efivarfs_fs_info *sbi =3D sb->s_fs_info; + struct efivarfs_mount_opts *opts =3D &sbi->mount_opts; + + if (!uid_eq(opts->uid, GLOBAL_ROOT_UID)) + seq_printf(m, ",uid=3D%u", + from_kuid_munged(&init_user_ns, opts->uid)); + if (!gid_eq(opts->gid, GLOBAL_ROOT_GID)) + seq_printf(m, ",gid=3D%u", + from_kgid_munged(&init_user_ns, opts->gid)); + return 0; +} + static int efivarfs_statfs(struct dentry *dentry, struct kstatfs *buf) { const u32 attr =3D EFI_VARIABLE_NON_VOLATILE | @@ -64,6 +80,7 @@ static const struct super_operations efivarfs_ops =3D { .statfs =3D efivarfs_statfs, .drop_inode =3D generic_delete_inode, .evict_inode =3D efivarfs_evict_inode, + .show_options =3D efivarfs_show_options, }; =20 /* @@ -225,6 +242,45 @@ static int efivarfs_destroy(struct efivar_entry *entry= , void *data) return 0; } =20 +enum { + Opt_uid, Opt_gid, +}; + +static const struct fs_parameter_spec efivarfs_parameters[] =3D { + 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 =3D fc->s_fs_info; + struct efivarfs_mount_opts *opts =3D &sbi->mount_opts; + struct fs_parse_result result; + int opt; + + opt =3D fs_parse(fc, efivarfs_parameters, param, &result); + if (opt < 0) + return opt; + + switch (opt) { + case Opt_uid: + opts->uid =3D make_kuid(current_user_ns(), result.uint_32); + if (!uid_valid(opts->uid)) + return -EINVAL; + break; + case Opt_gid: + opts->gid =3D 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 =3D NULL; @@ -270,11 +326,22 @@ static int efivarfs_get_tree(struct fs_context *fc) } =20 static const struct fs_context_operations efivarfs_context_ops =3D { - .get_tree =3D efivarfs_get_tree, + .get_tree =3D efivarfs_get_tree, + .parse_param =3D efivarfs_parse_param, }; =20 static int efivarfs_init_fs_context(struct fs_context *fc) { + struct efivarfs_fs_info *sfi; + + sfi =3D kzalloc(sizeof(*sfi), GFP_KERNEL); + if (!sfi) + return -ENOMEM; + + sfi->mount_opts.uid =3D GLOBAL_ROOT_UID; + sfi->mount_opts.gid =3D GLOBAL_ROOT_GID; + + fc->s_fs_info =3D sfi; fc->ops =3D &efivarfs_context_ops; return 0; } @@ -291,10 +358,11 @@ static void efivarfs_kill_sb(struct super_block *sb) } =20 static struct file_system_type efivarfs_type =3D { - .owner =3D THIS_MODULE, - .name =3D "efivarfs", + .owner =3D THIS_MODULE, + .name =3D "efivarfs", .init_fs_context =3D efivarfs_init_fs_context, .kill_sb =3D efivarfs_kill_sb, + .parameters =3D efivarfs_parameters, }; =20 static __init int efivarfs_init(void) --=20 2.42.0.283.g2d96d420d3-goog