From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from out02.mta.xmission.com ([166.70.13.232]:44995 "EHLO out02.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751132AbdGOH6b (ORCPT ); Sat, 15 Jul 2017 03:58:31 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: "Levin\, Alexander \(Sasha Levin\)" Cc: "linux-kernel\@vger.kernel.org" , "stable\@vger.kernel.org" References: <20170715012538.10101-1-alexander.levin@verizon.com> <20170715012538.10101-72-alexander.levin@verizon.com> Date: Sat, 15 Jul 2017 02:50:30 -0500 In-Reply-To: <20170715012538.10101-72-alexander.levin@verizon.com> (Alexander Levin's message of "Sat, 15 Jul 2017 01:26:22 +0000") Message-ID: <871spinnp5.fsf@xmission.com> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [PATCH for v4.9 LTS 72/87] libfs: Modify mount_pseudo_xattr to be clear it is not a userspace mount Sender: stable-owner@vger.kernel.org List-ID: *Scratches my head* Is there code in v4.9 where this matters? At the time I merged this to my knowledge there were no in kernel users that cared. Which is why I did not cc stable in the first place. Eric "Levin, Alexander (Sasha Levin)" writes: > From: "Eric W. Biederman" > > [ Upstream commit 75422726b0f717d67db3283c2eb5bc14fa2619c5 ] > > Add MS_KERNMOUNT to the flags that are passed. > Use sget_userns and force &init_user_ns instead of calling sget so that > even if called from a weird context the internal filesystem will be > considered to be in the intial user namespace. > > Luis Ressel reported that the the failure to pass MS_KERNMOUNT into > mount_pseudo broke his in development graphics driver that uses the > generic drm infrastructure. I am not certain the deriver was bug > free in it's usage of that infrastructure but since > mount_pseudo_xattr can never be triggered by userspace it is clearer > and less error prone, and less problematic for the code to be explicit. > > Reported-by: Luis Ressel > Tested-by: Luis Ressel > Acked-by: Al Viro > Signed-off-by: "Eric W. Biederman" > Signed-off-by: Sasha Levin > --- > fs/libfs.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/fs/libfs.c b/fs/libfs.c > index 48826d4da189..9588780ad43e 100644 > --- a/fs/libfs.c > +++ b/fs/libfs.c > @@ -245,7 +245,8 @@ struct dentry *mount_pseudo_xattr(struct file_system_type *fs_type, char *name, > struct inode *root; > struct qstr d_name = QSTR_INIT(name, strlen(name)); > > - s = sget(fs_type, NULL, set_anon_super, MS_NOUSER, NULL); > + s = sget_userns(fs_type, NULL, set_anon_super, MS_KERNMOUNT|MS_NOUSER, > + &init_user_ns, NULL); > if (IS_ERR(s)) > return ERR_CAST(s);