From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, T_DKIMWL_WL_MED,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by aws-us-west-2-korg-lkml-1.web.codeaurora.org (Postfix) with ESMTP id EB014C433EF for ; Mon, 11 Jun 2018 19:58:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8A28C2087E for ; Mon, 11 Jun 2018 19:58:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="j6IAEkez" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8A28C2087E Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934767AbeFKT6P (ORCPT ); Mon, 11 Jun 2018 15:58:15 -0400 Received: from mail-pl0-f67.google.com ([209.85.160.67]:34428 "EHLO mail-pl0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933650AbeFKT6N (ORCPT ); Mon, 11 Jun 2018 15:58:13 -0400 Received: by mail-pl0-f67.google.com with SMTP id g20-v6so12944143plq.1 for ; Mon, 11 Jun 2018 12:58:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=0AZjJCeLCewPmn+bJ7h9PP7uZdcRlZqeoAFa0Ux4SB0=; b=j6IAEkez66CJafcI2waFRXnP7v91wsVDX+lRQ5Fx1Zo7dqff8TUJgL7wp4FO2VkXd/ g5qnEeUFdrpC/dC0NXuxclXIPCd7bBkYIWOsXb0rBWI4VCMdXmvfVA6PV6XV9xeP3FLY gdL4P+ziIcQlTzrzs0qnSPRA/29QAErK9n5L5WFQXDYY+GvLGHg3tpkaLR2gHb3dyyNP edZ/T/ZhS1ok5kdpO1tIc8kherUnY/gKwehEo7N+Sv4lC3X02a7fszHrIAHbNgm7g/aI ElnAkr/tiJBp84ez0QT2LWTpOh+ziRorzrAkhwCAjhlmBVMyt+t4+/aGplkHLvWQFe3m BZZw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=0AZjJCeLCewPmn+bJ7h9PP7uZdcRlZqeoAFa0Ux4SB0=; b=FZZW0y7l70URnvJ0TKGvHlEDw9WQONrNjtjZZF7XwoombYQ3K+UMkxoFr8CSiaGYQq MlcH0FqS2/s7awKFqx18xkab4RDW7F4JSnXFh8xNA3ZdL1AJISTzvmG5ziYCyLpkl8FP eQw0RW9IKqDTkXMx1P2TP80ATEw1Ir/i6Ws16qWBvnrhK6701+fLxNOSn/zbfrHJxmPR GfYOGeoB9DixdEHiOjaSqzt6Xx2GwiBOtmOtGTBCyVL8DJkuHxlYN1VLO3F0IvnL/+L2 wdt4XYTIjnIz8eVTDStkV7QUoI/lM77Lir6d9hw7/iHqByoDnyYFKx1VUPOfU0Ab0zPV HihQ== X-Gm-Message-State: APt69E3KrZqmb1WnM6s7tpPKkiNFdan9F89UuPYtjUjl119Kmgd3jjS5 bqvfyayVr+qChlW9oFLCmFsdSw== X-Google-Smtp-Source: ADUXVKK2aBlfRi+OscN/USmFvD2bqiqhmy0NKYrXPPZypfkOaIvhVY/Y6Xfx5NB2PVt6Ms2GbDCKnw== X-Received: by 2002:a17:902:d20b:: with SMTP id t11-v6mr604542ply.282.1528747092872; Mon, 11 Jun 2018 12:58:12 -0700 (PDT) Received: from astrachan.mtv.corp.google.com ([2620:0:1000:1600:4394:e3d:8eee:a828]) by smtp.gmail.com with ESMTPSA id z16-v6sm78371773pge.90.2018.06.11.12.58.11 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 11 Jun 2018 12:58:12 -0700 (PDT) From: Alistair Strachan To: linux-fsdevel@vger.kernel.org Cc: Alistair Strachan , Seth Forshee , Djalal Harouni , "Eric W. Biederman" , kernel-team@android.com, linux-kernel@vger.kernel.org Subject: [PATCH] proc: Fix parsing of mount parameters. Date: Mon, 11 Jun 2018 12:57:44 -0700 Message-Id: <20180611195744.154962-1-astrachan@google.com> X-Mailer: git-send-email 2.18.0.rc1.242.g61856ae69a-goog Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In commit e94591d0d90c "proc: Convert proc_mount to use mount_ns" the parsing of mount parameters for the proc filesystem was broken. The SB_KERNMOUNT for procfs happens via: start_kernel() rest_init() kernel_thread() _do_fork() copy_process() alloc_pid() pid_ns_prepare_proc() kern_mount_data() proc_mount() mount_ns() In mount_ns(), the kernel calls proc_fill_super() only if the superblock has not previously been set up (i.e. the first mount reference), regardless of SB_KERNMOUNT. Because the call to proc_parse_options() had been moved inside here, and the SB_KERNMOUNT uses no mount options, the option parser became a no-op. When userspace later mounted procfs with e.g. hidepid=2, the options would be ignored. This change backs out a part of the original cleanup and parses the procfs mount options at every mount call. Because the options currently only update the pid_ns for the mount, they are applied for all mounts of proc by that pid or childen of that pid, instantaneously. This is the same behavior as the original code. Fixes: e94591d0d90c ("proc: Convert proc_mount to use mount_ns") Signed-off-by: Alistair Strachan Cc: Seth Forshee Cc: Djalal Harouni Cc: "Eric W. Biederman" Cc: kernel-team@android.com Cc: linux-kernel@vger.kernel.org --- fs/proc/inode.c | 4 ---- fs/proc/internal.h | 1 - fs/proc/root.c | 5 ++++- 3 files changed, 4 insertions(+), 6 deletions(-) diff --git a/fs/proc/inode.c b/fs/proc/inode.c index 2cf3b74391ca..bbbbf348be0a 100644 --- a/fs/proc/inode.c +++ b/fs/proc/inode.c @@ -492,13 +492,9 @@ struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de) int proc_fill_super(struct super_block *s, void *data, int silent) { - struct pid_namespace *ns = get_pid_ns(s->s_fs_info); struct inode *root_inode; int ret; - if (!proc_parse_options(data, ns)) - return -EINVAL; - /* User space would break if executables or devices appear on proc */ s->s_iflags |= SB_I_USERNS_VISIBLE | SB_I_NOEXEC | SB_I_NODEV; s->s_flags |= SB_NODIRATIME | SB_NOSUID | SB_NOEXEC; diff --git a/fs/proc/internal.h b/fs/proc/internal.h index 50cb22a08c2f..89b7e845b000 100644 --- a/fs/proc/internal.h +++ b/fs/proc/internal.h @@ -264,7 +264,6 @@ static inline void proc_tty_init(void) {} * root.c */ extern struct proc_dir_entry proc_root; -extern int proc_parse_options(char *options, struct pid_namespace *pid); extern void proc_self_init(void); extern int proc_remount(struct super_block *, int *, char *); diff --git a/fs/proc/root.c b/fs/proc/root.c index 61b7340b357a..d40676a5dd6c 100644 --- a/fs/proc/root.c +++ b/fs/proc/root.c @@ -36,7 +36,7 @@ static const match_table_t tokens = { {Opt_err, NULL}, }; -int proc_parse_options(char *options, struct pid_namespace *pid) +static int proc_parse_options(char *options, struct pid_namespace *pid) { char *p; substring_t args[MAX_OPT_ARGS]; @@ -98,6 +98,9 @@ static struct dentry *proc_mount(struct file_system_type *fs_type, ns = task_active_pid_ns(current); } + if (!proc_parse_options(data, ns)) + return ERR_PTR(-EINVAL); + return mount_ns(fs_type, flags, data, ns, ns->user_ns, proc_fill_super); } -- 2.18.0.rc1.242.g61856ae69a-goog