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[89.243.172.161]) by smtp.gmail.com with ESMTPSA id w11-v6sm27541529wrn.65.2018.10.17.07.31.26 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 17 Oct 2018 07:31:27 -0700 (PDT) Subject: Re: [PATCH 31/34] vfs: syscall: Add fspick() to select a superblock for reconfiguration [ver #12] To: David Howells Cc: Al Viro , linux-api@vger.kernel.org, torvalds@linux-foundation.org, ebiederm@xmission.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, mszeredi@redhat.com References: <19866.1539782101@warthog.procyon.org.uk> <68a2107f-bf70-055b-86cf-1ba2ba9422bf@gmail.com> <153754740781.17872.7869536526927736855.stgit@warthog.procyon.org.uk> <153754766004.17872.9829232103614083565.stgit@warthog.procyon.org.uk> <9b8bf436-65de-13b9-0002-0479d11c18ca@gmail.com> <20181013061141.GR32577@ZenIV.linux.org.uk> <28710.1539782412@warthog.procyon.org.uk> From: Alan Jenkins Message-ID: Date: Wed, 17 Oct 2018 15:31:26 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <28710.1539782412@warthog.procyon.org.uk> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-GB Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 17/10/2018 14:20, David Howells wrote: > David Howells wrote: > >> I should probably check that the picked point is actually a mountpoint. > The root of the mount object at the path specified, that is, perhaps with > something like the attached. > > David I agree.  I'm happy to see this is using the same check as do_remount(). * change filesystem flags. dir should be a physical root of filesystem. * If you've mounted a non-root directory somewhere and want to do remount * on it - tough luck. */ Thanks Alan > --- > diff --git a/fs/fsopen.c b/fs/fsopen.c > index f673e93ac456..aaaaa17a233c 100644 > --- a/fs/fsopen.c > +++ b/fs/fsopen.c > @@ -186,6 +186,10 @@ SYSCALL_DEFINE3(fspick, int, dfd, const char __user *, path, unsigned int, flags > if (ret < 0) > goto err; > > + ret = -EINVAL; > + if (target.mnt->mnt_root != target.dentry) > + goto err_path; > + > fc = vfs_new_fs_context(target.dentry->d_sb->s_type, target.dentry, > 0, 0, FS_CONTEXT_FOR_RECONFIGURE); > if (IS_ERR(fc)) { >