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From: Stephen Smalley <sds@tycho.nsa.gov>
To: Daniel Colascione <dancol@google.com>,
	timmurray@google.com, selinux@vger.kernel.org,
	linux-security-module@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	kvm@vger.kernel.org, viro@zeniv.linux.org.uk,
	paul@paul-moore.com, nnk@google.com, lokeshgidra@google.com,
	jmorris@namei.org
Subject: Re: [PATCH v4 1/3] Add a new LSM-supporting anonymous inode interface
Date: Fri, 27 Mar 2020 09:40:05 -0400
Message-ID: <3ed1ea71-f640-f332-812b-652c83598784@tycho.nsa.gov> (raw)
In-Reply-To: <20200326200634.222009-2-dancol@google.com>

On 3/26/20 4:06 PM, Daniel Colascione wrote:
> This change adds two new functions, anon_inode_getfile_secure and
> anon_inode_getfd_secure, that create anonymous-node files with
> individual non-S_PRIVATE inodes to which security modules can apply
> policy. Existing callers continue using the original singleton-inode
> kind of anonymous-inode file. We can transition anonymous inode users
> to the new kind of anonymous inode in individual patches for the sake
> of bisection and review.
> 
> The new functions accept an optional context_inode parameter that
> callers can use to provide additional contextual information to
> security modules, e.g., indicating that one anonymous struct file is a
> logical child of another, allowing a security model to propagate
> security information from one to the other.
> 
> Signed-off-by: Daniel Colascione <dancol@google.com>
> ---

> diff --git a/fs/anon_inodes.c b/fs/anon_inodes.c
> index 89714308c25b..024059e333dc 100644
> --- a/fs/anon_inodes.c
> +++ b/fs/anon_inodes.c
> @@ -55,75 +55,135 @@ static struct file_system_type anon_inode_fs_type = {
> +static struct inode *anon_inode_make_secure_inode(
> +	const char *name,
> +	const struct inode *context_inode,
> +	const struct file_operations *fops)

fops argument can be removed here too, unused now by this function.

>   /**
> - * anon_inode_getfd - 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_getfile_secure - creates a new file instance by hooking
> + *                             it up to a new anonymous inode and a
> + *                             dentry that describe the "class" of the
> + *                             file.  Make it possible to use security
> + *                             modules to control access to the
> + *                             new file.
>    *
>    * @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*

anon_inode_flags leftover from prior version of the patch, not an 
argument in the current code.  Likewise, the "for the file" addendum to 
the @flags argument description is a leftover and not needed.

 > + * 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_secure() will have distinct inodes, avoiding
 > + * code duplication for the file/inode/dentry setup.

The two preceding sentences directly contradict each other.

> +/**
> + * 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.

This would be identical to the original except for different word 
wrapping.  Probably a leftover from prior version of the patch where you 
were modifying the existing interface.  Recommend reverting such changes 
to minimize unnecessary noise in your diff and meke it easier to tell 
what changes are real.

> + *
> + * @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 for the file
>    *
> - * 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

Unnecessary difference here; this interface does use a single inode.

> @@ -146,6 +207,57 @@ int anon_inode_getfd(const char *name, const struct file_operations *fops,
>   	put_unused_fd(fd);
>   	return error;
>   }
> +
> +/**
> + * anon_inode_getfd_secure - creates a new file instance by hooking it
> + *                           up to a new anonymous inode and a dentry
> + *                           that describe the "class" of the file.
> + *                           Make it possible to use security modules
> + *                           to control access to the new file.
> + *
> + * @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
> + *
 > + * 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_secure() will have distinct inodes, avoiding
 > + * code duplication for the file/inode/dentry setup.

The two preceding sentences contradict each other.


  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
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 [this message]
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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