From: Daniel Colascione <dancol@google.com> To: Stephen Smalley <sds@tycho.nsa.gov> Cc: Tim Murray <timmurray@google.com>, Nosh Minwalla <nosh@google.com>, Nick Kralevich <nnk@google.com>, Lokesh Gidra <lokeshgidra@google.com>, linux-kernel <linux-kernel@vger.kernel.org>, Linux API <linux-api@vger.kernel.org>, selinux@vger.kernel.org Subject: Re: [PATCH v2 1/6] Add a new flags-accepting interface for anonymous inodes Date: Wed, 12 Feb 2020 09:23:09 -0800 Message-ID: <CAKOZuet1vcDwkqoJgqmDjg7pjLGfvh11ZdUZpoyoXXWdz9Y4CQ@mail.gmail.com> (raw) In-Reply-To: <88ea16bd-38be-b4f9-dfb3-e0626f5b6aaf@tycho.nsa.gov> Thanks again for the review. On Wed, Feb 12, 2020 at 8:36 AM Stephen Smalley <sds@tycho.nsa.gov> wrote: > > On 2/11/20 5:55 PM, Daniel Colascione wrote: > > Add functions forwarding from the old names to the new ones so we > > don't need to change any callers. > > > > Signed-off-by: Daniel Colascione <dancol@google.com> > > (please add linux-fsdevel, viro to cc on future versions of this patch > since this is a VFS change) > > > --- > > fs/anon_inodes.c | 62 ++++++++++++++++++++++--------------- > > include/linux/anon_inodes.h | 27 +++++++++++++--- > > 2 files changed, 59 insertions(+), 30 deletions(-) > > > > diff --git a/fs/anon_inodes.c b/fs/anon_inodes.c > > index 89714308c25b..caa36019afca 100644 > > --- a/fs/anon_inodes.c > > +++ b/fs/anon_inodes.c > > @@ -56,60 +56,71 @@ static struct file_system_type anon_inode_fs_type = { > > }; > > > > /** > > - * anon_inode_getfile - creates a new file instance by hooking it up to an > > - * anonymous inode, and a dentry that describe the "class" > > - * of the file > > + * anon_inode_getfile2 - creates a new file instance by hooking it up to > > + * an anonymous inode, and a dentry that describe > > + * the "class" of the file > > Not going to bikeshed on names but anon_inode_getfile_flags or _secure > or something would be more descriptive. _flags is fine, but I think _secure is overfitting. > > * > > * @name: [in] name of the "class" of the new file > > * @fops: [in] file operations for the new file > > * @priv: [in] private data for the new file (will be file's private_data) > > - * @flags: [in] flags > > + * @flags: [in] flags for the file > > + * @anon_inode_flags: [in] flags for anon_inode* > > Do we really envision ever needing more than one new flag here? If not, > then making it a bool secure parameter or encoding it as an > unused/ignored flag bit in the existing flags argument would seem > preferable. A bool and a flag is the same as far as the machine is concerned with respect to argument passing, and I find the flag much more descriptive than a bare "true" or a "false" scattered at call sites. Besides, a flags argument could lead to less churn later. > In some cases, we actually want the "anon inode" to inherit the security > context of a related inode (e.g. ioctls on /dev/kvm can create anon > inodes representing VMs, vCPUs, etc and further ioctls are performed on > those inodes), in which case we may need the caller to pass in the > related inode as well. See my other reply on this subject. Passing an optional related inode seems like a decent approach here. > > * > > - * Creates a new file by hooking it on a single inode. This is useful for files > > + * Creates a new file by hooking it on an unspecified inode. This is useful for files > > * that do not need to have a full-fledged inode in order to operate correctly. > > * All the files created with anon_inode_getfile() will share a single inode, > > * hence saving memory and avoiding code duplication for the file/inode/dentry > > * setup. Returns the newly created file* or an error pointer. > > + * > > + * anon_inode_flags must be zero. > > */ > > -struct file *anon_inode_getfile(const char *name, > > - const struct file_operations *fops, > > - void *priv, int flags) > > +struct file *anon_inode_getfile2(const char *name, > > + const struct file_operations *fops, > > + void *priv, int flags, int anon_inode_flags) > > { > > + struct inode *inode; > > struct file *file; > > > > - if (IS_ERR(anon_inode_inode)) > > - return ERR_PTR(-ENODEV); > > - > > - if (fops->owner && !try_module_get(fops->owner)) > > - return ERR_PTR(-ENOENT); > > + if (anon_inode_flags) > > + return ERR_PTR(-EINVAL); > > Not sure this is how it is normally done (i.e. one patch to just > introduce an extended interface but disallow all use of it, then a > separate patch to introduce the first use). Would recommend combining; > otherwise reviewers can't see how it will be used without looking at both. All things being equal, finer-grained patches are better: they allow for easier bisection. But I don't feel strongly one way or the other here, so let's see what other reviewers say.
next prev parent reply index Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-02-11 22:55 [PATCH v2 0/6] Harden userfaultfd Daniel Colascione 2020-02-11 22:55 ` [PATCH v2 1/6] Add a new flags-accepting interface for anonymous inodes Daniel Colascione 2020-02-12 16:37 ` Stephen Smalley 2020-02-12 17:23 ` Daniel Colascione [this message] 2020-02-11 22:55 ` [PATCH v2 2/6] Add a concept of a "secure" anonymous file Daniel Colascione 2020-02-12 16:49 ` Stephen Smalley 2020-02-14 22:13 ` kbuild test robot 2020-02-11 22:55 ` [PATCH v2 3/6] Teach SELinux about a new userfaultfd class Daniel Colascione 2020-02-12 17:05 ` Stephen Smalley 2020-02-12 17:19 ` Daniel Colascione 2020-02-12 18:04 ` Stephen Smalley 2020-02-12 18:59 ` Stephen Smalley 2020-02-12 19:04 ` Daniel Colascione 2020-02-12 19:11 ` Stephen Smalley 2020-02-12 19:13 ` Daniel Colascione 2020-02-12 19:17 ` Stephen Smalley 2020-02-11 22:55 ` [PATCH v2 4/6] Wire UFFD up to SELinux Daniel Colascione 2020-02-11 22:55 ` [PATCH v2 5/6] Let userfaultfd opt out of handling kernel-mode faults Daniel Colascione 2020-02-11 22:55 ` [PATCH v2 6/6] Add a new sysctl for limiting userfaultfd to user mode faults Daniel Colascione 2020-02-11 23:13 ` [PATCH v2 0/6] Harden userfaultfd Casey Schaufler 2020-02-11 23:27 ` Daniel Colascione 2020-02-12 16:09 ` Stephen Smalley 2020-02-21 17:56 ` James Morris 2020-02-12 7:50 ` Kees Cook 2020-02-12 16:54 ` Jann Horn 2020-02-12 17:14 ` Peter Xu 2020-02-12 19:41 ` Andrea Arcangeli 2020-02-12 20:04 ` Daniel Colascione 2020-02-12 23:41 ` Andrea Arcangeli 2020-02-12 17:12 ` Daniel Colascione 2020-02-14 3:26 ` [PATCH 0/3] SELinux support for anonymous inodes and UFFD Daniel Colascione 2020-02-14 3:26 ` [PATCH 1/3] Add a new LSM-supporting anonymous inode interface Daniel Colascione 2020-02-14 3:26 ` [PATCH 2/3] Teach SELinux about anonymous inodes Daniel Colascione 2020-02-14 16:39 ` Stephen Smalley 2020-02-14 17:21 ` Daniel Colascione 2020-02-14 18:02 ` Stephen Smalley 2020-02-14 18:08 ` Stephen Smalley 2020-02-14 20:24 ` Stephen Smalley 2020-02-14 3:26 ` [PATCH 3/3] Wire UFFD up to SELinux Daniel Colascione 2020-03-25 23:02 ` [PATCH v2 0/3] SELinux support for anonymous inodes and UFFD Daniel Colascione 2020-03-25 23:02 ` [PATCH v2 1/3] Add a new LSM-supporting anonymous inode interface Daniel Colascione 2020-03-26 13:53 ` Stephen Smalley 2020-03-25 23:02 ` [PATCH v2 2/3] Teach SELinux about anonymous inodes Daniel Colascione 2020-03-26 13:58 ` Stephen Smalley 2020-03-26 17:59 ` Daniel Colascione 2020-03-26 17:37 ` Stephen Smalley 2020-03-25 23:02 ` [PATCH v2 3/3] Wire UFFD up to SELinux Daniel Colascione 2020-03-25 23:49 ` Casey Schaufler 2020-03-26 18:14 ` [PATCH v3 0/3] SELinux support for anonymous inodes and UFFD Daniel Colascione 2020-03-26 18:14 ` [PATCH v3 1/3] Add a new LSM-supporting anonymous inode interface Daniel Colascione 2020-03-26 19:00 ` Stephen Smalley 2020-03-26 18:14 ` [PATCH v3 2/3] Teach SELinux about anonymous inodes Daniel Colascione 2020-03-26 19:02 ` Stephen Smalley 2020-03-26 18:14 ` [PATCH v3 3/3] Wire UFFD up to SELinux Daniel Colascione 2020-03-26 20:06 ` [PATCH v4 0/3] SELinux support for anonymous inodes and UFFD Daniel Colascione 2020-03-26 20:06 ` [PATCH v4 1/3] Add a new LSM-supporting anonymous inode interface Daniel Colascione 2020-03-27 13:40 ` Stephen Smalley 2020-03-26 20:06 ` [PATCH v4 2/3] Teach SELinux about anonymous inodes Daniel Colascione 2020-03-27 13:41 ` Stephen Smalley 2020-03-26 20:06 ` [PATCH v4 3/3] Wire UFFD up to SELinux Daniel Colascione 2020-04-01 21:39 ` [PATCH v5 0/3] SELinux support for anonymous inodes and UFFD Daniel Colascione 2020-04-01 21:39 ` [PATCH v5 1/3] Add a new LSM-supporting anonymous inode interface Daniel Colascione 2020-05-07 16:02 ` James Morris 2020-08-04 21:22 ` Eric Biggers 2020-04-01 21:39 ` [PATCH v5 2/3] Teach SELinux about anonymous inodes Daniel Colascione 2020-04-01 21:39 ` [PATCH v5 3/3] Wire UFFD up to SELinux Daniel Colascione 2020-08-04 21:16 ` Eric Biggers 2020-04-13 13:29 ` [PATCH v5 0/3] SELinux support for anonymous inodes and UFFD Daniel Colascione 2020-04-22 16:55 ` James Morris 2020-04-22 17:12 ` Casey Schaufler 2020-04-23 22:24 ` Casey Schaufler 2020-04-27 16:18 ` Casey Schaufler 2020-04-27 16:48 ` Stephen Smalley 2020-04-27 17:12 ` Casey Schaufler 2020-04-29 17:02 ` Stephen Smalley 2020-04-27 17:15 ` Casey Schaufler 2020-04-27 19:40 ` Stephen Smalley 2020-06-04 3:56 ` James Morris 2020-06-04 18:51 ` Stephen Smalley 2020-06-04 19:24 ` Lokesh Gidra
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