diff mbox series

[v4,1/3,security] Add new hook to compare new mount to an existing mount

Message ID 20210227033755.24460-1-olga.kornievskaia@gmail.com (mailing list archive)
State New
Headers show
Series [v4,1/3,security] Add new hook to compare new mount to an existing mount | expand

Commit Message

Olga Kornievskaia Feb. 27, 2021, 3:37 a.m. UTC
From: Olga Kornievskaia <kolga@netapp.com>

Add a new hook that takes an existing super block and a new mount
with new options and determines if new options confict with an
existing mount or not.

A filesystem can use this new hook to determine if it can share
the an existing superblock with a new superblock for the new mount.

Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
---
 include/linux/lsm_hook_defs.h |  1 +
 include/linux/lsm_hooks.h     |  6 ++++
 include/linux/security.h      |  8 +++++
 security/security.c           |  7 +++++
 security/selinux/hooks.c      | 56 +++++++++++++++++++++++++++++++++++
 5 files changed, 78 insertions(+)

Comments

Anna Schumaker March 2, 2021, 6:20 p.m. UTC | #1
Hi Casey,

On Fri, Feb 26, 2021 at 10:40 PM Olga Kornievskaia
<olga.kornievskaia@gmail.com> wrote:
>
> From: Olga Kornievskaia <kolga@netapp.com>
>
> Add a new hook that takes an existing super block and a new mount
> with new options and determines if new options confict with an
> existing mount or not.
>
> A filesystem can use this new hook to determine if it can share
> the an existing superblock with a new superblock for the new mount.
>
> Signed-off-by: Olga Kornievskaia <kolga@netapp.com>

Do you have any other thoughts on this patch? I'm also wondering how
you want to handle sending it upstream. I'm happy to take it through
the NFS tree (with an acked-by) for a 5.12-rc with Olga's bugfix
patches, but if you have other thoughts or plans then let me know!

Thanks,
Anna

> ---
>  include/linux/lsm_hook_defs.h |  1 +
>  include/linux/lsm_hooks.h     |  6 ++++
>  include/linux/security.h      |  8 +++++
>  security/security.c           |  7 +++++
>  security/selinux/hooks.c      | 56 +++++++++++++++++++++++++++++++++++
>  5 files changed, 78 insertions(+)
>
> diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
> index 7aaa753b8608..1b12a5266a51 100644
> --- a/include/linux/lsm_hook_defs.h
> +++ b/include/linux/lsm_hook_defs.h
> @@ -62,6 +62,7 @@ LSM_HOOK(int, 0, sb_alloc_security, struct super_block *sb)
>  LSM_HOOK(void, LSM_RET_VOID, sb_free_security, struct super_block *sb)
>  LSM_HOOK(void, LSM_RET_VOID, sb_free_mnt_opts, void *mnt_opts)
>  LSM_HOOK(int, 0, sb_eat_lsm_opts, char *orig, void **mnt_opts)
> +LSM_HOOK(int, 0, sb_mnt_opts_compat, struct super_block *sb, void *mnt_opts)
>  LSM_HOOK(int, 0, sb_remount, struct super_block *sb, void *mnt_opts)
>  LSM_HOOK(int, 0, sb_kern_mount, struct super_block *sb)
>  LSM_HOOK(int, 0, sb_show_options, struct seq_file *m, struct super_block *sb)
> diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
> index a19adef1f088..0de8eb2ea547 100644
> --- a/include/linux/lsm_hooks.h
> +++ b/include/linux/lsm_hooks.h
> @@ -142,6 +142,12 @@
>   *     @orig the original mount data copied from userspace.
>   *     @copy copied data which will be passed to the security module.
>   *     Returns 0 if the copy was successful.
> + * @sb_mnt_opts_compat:
> + *     Determine if the new mount options in @mnt_opts are allowed given
> + *     the existing mounted filesystem at @sb.
> + *     @sb superblock being compared
> + *     @mnt_opts new mount options
> + *     Return 0 if options are compatible.
>   * @sb_remount:
>   *     Extracts security system specific mount options and verifies no changes
>   *     are being made to those options.
> diff --git a/include/linux/security.h b/include/linux/security.h
> index c35ea0ffccd9..50db3d5d1608 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -291,6 +291,7 @@ int security_sb_alloc(struct super_block *sb);
>  void security_sb_free(struct super_block *sb);
>  void security_free_mnt_opts(void **mnt_opts);
>  int security_sb_eat_lsm_opts(char *options, void **mnt_opts);
> +int security_sb_mnt_opts_compat(struct super_block *sb, void *mnt_opts);
>  int security_sb_remount(struct super_block *sb, void *mnt_opts);
>  int security_sb_kern_mount(struct super_block *sb);
>  int security_sb_show_options(struct seq_file *m, struct super_block *sb);
> @@ -635,6 +636,13 @@ static inline int security_sb_remount(struct super_block *sb,
>         return 0;
>  }
>
> +static inline int security_sb_mnt_opts_compat(struct super_block *sb,
> +                                             void *mnt_opts)
> +{
> +       return 0;
> +}
> +
> +
>  static inline int security_sb_kern_mount(struct super_block *sb)
>  {
>         return 0;
> diff --git a/security/security.c b/security/security.c
> index 7b09cfbae94f..56cf5563efde 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -890,6 +890,13 @@ int security_sb_eat_lsm_opts(char *options, void **mnt_opts)
>  }
>  EXPORT_SYMBOL(security_sb_eat_lsm_opts);
>
> +int security_sb_mnt_opts_compat(struct super_block *sb,
> +                               void *mnt_opts)
> +{
> +       return call_int_hook(sb_mnt_opts_compat, 0, sb, mnt_opts);
> +}
> +EXPORT_SYMBOL(security_sb_mnt_opts_compat);
> +
>  int security_sb_remount(struct super_block *sb,
>                         void *mnt_opts)
>  {
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index 644b17ec9e63..afee3a222a0e 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -2656,6 +2656,61 @@ static int selinux_sb_eat_lsm_opts(char *options, void **mnt_opts)
>         return rc;
>  }
>
> +static int selinux_sb_mnt_opts_compat(struct super_block *sb, void *mnt_opts)
> +{
> +       struct selinux_mnt_opts *opts = mnt_opts;
> +       struct superblock_security_struct *sbsec = sb->s_security;
> +       u32 sid;
> +       int rc;
> +
> +       /*
> +        * Superblock not initialized (i.e. no options) - reject if any
> +        * options specified, otherwise accept.
> +        */
> +       if (!(sbsec->flags & SE_SBINITIALIZED))
> +               return opts ? 1 : 0;
> +
> +       /*
> +        * Superblock initialized and no options specified - reject if
> +        * superblock has any options set, otherwise accept.
> +        */
> +       if (!opts)
> +               return (sbsec->flags & SE_MNTMASK) ? 1 : 0;
> +
> +       if (opts->fscontext) {
> +               rc = parse_sid(sb, opts->fscontext, &sid);
> +               if (rc)
> +                       return 1;
> +               if (bad_option(sbsec, FSCONTEXT_MNT, sbsec->sid, sid))
> +                       return 1;
> +       }
> +       if (opts->context) {
> +               rc = parse_sid(sb, opts->context, &sid);
> +               if (rc)
> +                       return 1;
> +               if (bad_option(sbsec, CONTEXT_MNT, sbsec->mntpoint_sid, sid))
> +                       return 1;
> +       }
> +       if (opts->rootcontext) {
> +               struct inode_security_struct *root_isec;
> +
> +               root_isec = backing_inode_security(sb->s_root);
> +               rc = parse_sid(sb, opts->rootcontext, &sid);
> +               if (rc)
> +                       return 1;
> +               if (bad_option(sbsec, ROOTCONTEXT_MNT, root_isec->sid, sid))
> +                       return 1;
> +       }
> +       if (opts->defcontext) {
> +               rc = parse_sid(sb, opts->defcontext, &sid);
> +               if (rc)
> +                       return 1;
> +               if (bad_option(sbsec, DEFCONTEXT_MNT, sbsec->def_sid, sid))
> +                       return 1;
> +       }
> +       return 0;
> +}
> +
>  static int selinux_sb_remount(struct super_block *sb, void *mnt_opts)
>  {
>         struct selinux_mnt_opts *opts = mnt_opts;
> @@ -6984,6 +7039,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
>
>         LSM_HOOK_INIT(sb_free_security, selinux_sb_free_security),
>         LSM_HOOK_INIT(sb_free_mnt_opts, selinux_free_mnt_opts),
> +       LSM_HOOK_INIT(sb_mnt_opts_compat, selinux_sb_mnt_opts_compat),
>         LSM_HOOK_INIT(sb_remount, selinux_sb_remount),
>         LSM_HOOK_INIT(sb_kern_mount, selinux_sb_kern_mount),
>         LSM_HOOK_INIT(sb_show_options, selinux_sb_show_options),
> --
> 2.27.0
>
Casey Schaufler March 2, 2021, 6:51 p.m. UTC | #2
On 3/2/2021 10:20 AM, Anna Schumaker wrote:
> Hi Casey,
>
> On Fri, Feb 26, 2021 at 10:40 PM Olga Kornievskaia
> <olga.kornievskaia@gmail.com> wrote:
>> From: Olga Kornievskaia <kolga@netapp.com>
>>
>> Add a new hook that takes an existing super block and a new mount
>> with new options and determines if new options confict with an
>> existing mount or not.
>>
>> A filesystem can use this new hook to determine if it can share
>> the an existing superblock with a new superblock for the new mount.
>>
>> Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
> Do you have any other thoughts on this patch? I'm also wondering how
> you want to handle sending it upstream. 

James Morris is the maintainer for the security sub-system,
so you'll want to send this through him. He will want you to
have an ACK from Paul Moore, who is the SELinux maintainer.

> I'm happy to take it through
> the NFS tree (with an acked-by) for a 5.12-rc with Olga's bugfix
> patches, but if you have other thoughts or plans then let me know!
>
> Thanks,
> Anna
>
>> ---
>>  include/linux/lsm_hook_defs.h |  1 +
>>  include/linux/lsm_hooks.h     |  6 ++++
>>  include/linux/security.h      |  8 +++++
>>  security/security.c           |  7 +++++
>>  security/selinux/hooks.c      | 56 +++++++++++++++++++++++++++++++++++
>>  5 files changed, 78 insertions(+)
>>
>> diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
>> index 7aaa753b8608..1b12a5266a51 100644
>> --- a/include/linux/lsm_hook_defs.h
>> +++ b/include/linux/lsm_hook_defs.h
>> @@ -62,6 +62,7 @@ LSM_HOOK(int, 0, sb_alloc_security, struct super_block *sb)
>>  LSM_HOOK(void, LSM_RET_VOID, sb_free_security, struct super_block *sb)
>>  LSM_HOOK(void, LSM_RET_VOID, sb_free_mnt_opts, void *mnt_opts)
>>  LSM_HOOK(int, 0, sb_eat_lsm_opts, char *orig, void **mnt_opts)
>> +LSM_HOOK(int, 0, sb_mnt_opts_compat, struct super_block *sb, void *mnt_opts)
>>  LSM_HOOK(int, 0, sb_remount, struct super_block *sb, void *mnt_opts)
>>  LSM_HOOK(int, 0, sb_kern_mount, struct super_block *sb)
>>  LSM_HOOK(int, 0, sb_show_options, struct seq_file *m, struct super_block *sb)
>> diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
>> index a19adef1f088..0de8eb2ea547 100644
>> --- a/include/linux/lsm_hooks.h
>> +++ b/include/linux/lsm_hooks.h
>> @@ -142,6 +142,12 @@
>>   *     @orig the original mount data copied from userspace.
>>   *     @copy copied data which will be passed to the security module.
>>   *     Returns 0 if the copy was successful.
>> + * @sb_mnt_opts_compat:
>> + *     Determine if the new mount options in @mnt_opts are allowed given
>> + *     the existing mounted filesystem at @sb.
>> + *     @sb superblock being compared
>> + *     @mnt_opts new mount options
>> + *     Return 0 if options are compatible.
>>   * @sb_remount:
>>   *     Extracts security system specific mount options and verifies no changes
>>   *     are being made to those options.
>> diff --git a/include/linux/security.h b/include/linux/security.h
>> index c35ea0ffccd9..50db3d5d1608 100644
>> --- a/include/linux/security.h
>> +++ b/include/linux/security.h
>> @@ -291,6 +291,7 @@ int security_sb_alloc(struct super_block *sb);
>>  void security_sb_free(struct super_block *sb);
>>  void security_free_mnt_opts(void **mnt_opts);
>>  int security_sb_eat_lsm_opts(char *options, void **mnt_opts);
>> +int security_sb_mnt_opts_compat(struct super_block *sb, void *mnt_opts);
>>  int security_sb_remount(struct super_block *sb, void *mnt_opts);
>>  int security_sb_kern_mount(struct super_block *sb);
>>  int security_sb_show_options(struct seq_file *m, struct super_block *sb);
>> @@ -635,6 +636,13 @@ static inline int security_sb_remount(struct super_block *sb,
>>         return 0;
>>  }
>>
>> +static inline int security_sb_mnt_opts_compat(struct super_block *sb,
>> +                                             void *mnt_opts)
>> +{
>> +       return 0;
>> +}
>> +
>> +
>>  static inline int security_sb_kern_mount(struct super_block *sb)
>>  {
>>         return 0;
>> diff --git a/security/security.c b/security/security.c
>> index 7b09cfbae94f..56cf5563efde 100644
>> --- a/security/security.c
>> +++ b/security/security.c
>> @@ -890,6 +890,13 @@ int security_sb_eat_lsm_opts(char *options, void **mnt_opts)
>>  }
>>  EXPORT_SYMBOL(security_sb_eat_lsm_opts);
>>
>> +int security_sb_mnt_opts_compat(struct super_block *sb,
>> +                               void *mnt_opts)
>> +{
>> +       return call_int_hook(sb_mnt_opts_compat, 0, sb, mnt_opts);
>> +}
>> +EXPORT_SYMBOL(security_sb_mnt_opts_compat);
>> +
>>  int security_sb_remount(struct super_block *sb,
>>                         void *mnt_opts)
>>  {
>> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
>> index 644b17ec9e63..afee3a222a0e 100644
>> --- a/security/selinux/hooks.c
>> +++ b/security/selinux/hooks.c
>> @@ -2656,6 +2656,61 @@ static int selinux_sb_eat_lsm_opts(char *options, void **mnt_opts)
>>         return rc;
>>  }
>>
>> +static int selinux_sb_mnt_opts_compat(struct super_block *sb, void *mnt_opts)
>> +{
>> +       struct selinux_mnt_opts *opts = mnt_opts;
>> +       struct superblock_security_struct *sbsec = sb->s_security;
>> +       u32 sid;
>> +       int rc;
>> +
>> +       /*
>> +        * Superblock not initialized (i.e. no options) - reject if any
>> +        * options specified, otherwise accept.
>> +        */
>> +       if (!(sbsec->flags & SE_SBINITIALIZED))
>> +               return opts ? 1 : 0;
>> +
>> +       /*
>> +        * Superblock initialized and no options specified - reject if
>> +        * superblock has any options set, otherwise accept.
>> +        */
>> +       if (!opts)
>> +               return (sbsec->flags & SE_MNTMASK) ? 1 : 0;
>> +
>> +       if (opts->fscontext) {
>> +               rc = parse_sid(sb, opts->fscontext, &sid);
>> +               if (rc)
>> +                       return 1;
>> +               if (bad_option(sbsec, FSCONTEXT_MNT, sbsec->sid, sid))
>> +                       return 1;
>> +       }
>> +       if (opts->context) {
>> +               rc = parse_sid(sb, opts->context, &sid);
>> +               if (rc)
>> +                       return 1;
>> +               if (bad_option(sbsec, CONTEXT_MNT, sbsec->mntpoint_sid, sid))
>> +                       return 1;
>> +       }
>> +       if (opts->rootcontext) {
>> +               struct inode_security_struct *root_isec;
>> +
>> +               root_isec = backing_inode_security(sb->s_root);
>> +               rc = parse_sid(sb, opts->rootcontext, &sid);
>> +               if (rc)
>> +                       return 1;
>> +               if (bad_option(sbsec, ROOTCONTEXT_MNT, root_isec->sid, sid))
>> +                       return 1;
>> +       }
>> +       if (opts->defcontext) {
>> +               rc = parse_sid(sb, opts->defcontext, &sid);
>> +               if (rc)
>> +                       return 1;
>> +               if (bad_option(sbsec, DEFCONTEXT_MNT, sbsec->def_sid, sid))
>> +                       return 1;
>> +       }
>> +       return 0;
>> +}
>> +
>>  static int selinux_sb_remount(struct super_block *sb, void *mnt_opts)
>>  {
>>         struct selinux_mnt_opts *opts = mnt_opts;
>> @@ -6984,6 +7039,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
>>
>>         LSM_HOOK_INIT(sb_free_security, selinux_sb_free_security),
>>         LSM_HOOK_INIT(sb_free_mnt_opts, selinux_free_mnt_opts),
>> +       LSM_HOOK_INIT(sb_mnt_opts_compat, selinux_sb_mnt_opts_compat),
>>         LSM_HOOK_INIT(sb_remount, selinux_sb_remount),
>>         LSM_HOOK_INIT(sb_kern_mount, selinux_sb_kern_mount),
>>         LSM_HOOK_INIT(sb_show_options, selinux_sb_show_options),
>> --
>> 2.27.0
>>
Paul Moore March 5, 2021, 1:32 a.m. UTC | #3
On Tue, Mar 2, 2021 at 10:53 PM Casey Schaufler <casey@schaufler-ca.com> wrote:
> On 3/2/2021 10:20 AM, Anna Schumaker wrote:
> > Hi Casey,
> >
> > On Fri, Feb 26, 2021 at 10:40 PM Olga Kornievskaia
> > <olga.kornievskaia@gmail.com> wrote:
> >> From: Olga Kornievskaia <kolga@netapp.com>
> >>
> >> Add a new hook that takes an existing super block and a new mount
> >> with new options and determines if new options confict with an
> >> existing mount or not.
> >>
> >> A filesystem can use this new hook to determine if it can share
> >> the an existing superblock with a new superblock for the new mount.
> >>
> >> Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
> > Do you have any other thoughts on this patch? I'm also wondering how
> > you want to handle sending it upstream.
>
> James Morris is the maintainer for the security sub-system,
> so you'll want to send this through him. He will want you to
> have an ACK from Paul Moore, who is the SELinux maintainer.

In the past I've pulled patches such as this (new LSM hook, with only
a SELinux implementation of the new hook) in via the selinux/next tree
after the other LSMs have ACK'd the new hook.  This helps limit merge
problems with other SELinux changes and allows us (the SELinux folks)
to include it in the ongoing testing that we do during the -rcX
releases.

So Anna, if you or anyone else on the NFS side of the house want to
add your ACKs/REVIEWs/etc. please do so as I don't like merging
patches that cross subsystem boundaries without having all the
associated ACKs.  Casey, James, and other LSM folks please do the
same.
Anna Schumaker March 12, 2021, 3:45 p.m. UTC | #4
On Thu, Mar 4, 2021 at 8:34 PM Paul Moore <paul@paul-moore.com> wrote:
>
> On Tue, Mar 2, 2021 at 10:53 PM Casey Schaufler <casey@schaufler-ca.com> wrote:
> > On 3/2/2021 10:20 AM, Anna Schumaker wrote:
> > > Hi Casey,
> > >
> > > On Fri, Feb 26, 2021 at 10:40 PM Olga Kornievskaia
> > > <olga.kornievskaia@gmail.com> wrote:
> > >> From: Olga Kornievskaia <kolga@netapp.com>
> > >>
> > >> Add a new hook that takes an existing super block and a new mount
> > >> with new options and determines if new options confict with an
> > >> existing mount or not.
> > >>
> > >> A filesystem can use this new hook to determine if it can share
> > >> the an existing superblock with a new superblock for the new mount.
> > >>
> > >> Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
> > > Do you have any other thoughts on this patch? I'm also wondering how
> > > you want to handle sending it upstream.
> >
> > James Morris is the maintainer for the security sub-system,
> > so you'll want to send this through him. He will want you to
> > have an ACK from Paul Moore, who is the SELinux maintainer.
>
> In the past I've pulled patches such as this (new LSM hook, with only
> a SELinux implementation of the new hook) in via the selinux/next tree
> after the other LSMs have ACK'd the new hook.  This helps limit merge
> problems with other SELinux changes and allows us (the SELinux folks)
> to include it in the ongoing testing that we do during the -rcX
> releases.
>
> So Anna, if you or anyone else on the NFS side of the house want to
> add your ACKs/REVIEWs/etc. please do so as I don't like merging
> patches that cross subsystem boundaries without having all the
> associated ACKs.  Casey, James, and other LSM folks please do the
> same.

Sure:
Acked-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

Are you also going to take patch 3/3 that uses the new hook, or should
that go through the NFS tree? Patch 2/3 is a cleanup that can go
through the NFS tree.

Anna

>
> --
> paul moore
> www.paul-moore.com
Paul Moore March 12, 2021, 9:54 p.m. UTC | #5
On Fri, Mar 12, 2021 at 10:45 AM Anna Schumaker
<anna.schumaker@netapp.com> wrote:
> On Thu, Mar 4, 2021 at 8:34 PM Paul Moore <paul@paul-moore.com> wrote:
> > On Tue, Mar 2, 2021 at 10:53 PM Casey Schaufler <casey@schaufler-ca.com> wrote:
> > > On 3/2/2021 10:20 AM, Anna Schumaker wrote:
> > > > Hi Casey,
> > > >
> > > > On Fri, Feb 26, 2021 at 10:40 PM Olga Kornievskaia
> > > > <olga.kornievskaia@gmail.com> wrote:
> > > >> From: Olga Kornievskaia <kolga@netapp.com>
> > > >>
> > > >> Add a new hook that takes an existing super block and a new mount
> > > >> with new options and determines if new options confict with an
> > > >> existing mount or not.
> > > >>
> > > >> A filesystem can use this new hook to determine if it can share
> > > >> the an existing superblock with a new superblock for the new mount.
> > > >>
> > > >> Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
> > > > Do you have any other thoughts on this patch? I'm also wondering how
> > > > you want to handle sending it upstream.
> > >
> > > James Morris is the maintainer for the security sub-system,
> > > so you'll want to send this through him. He will want you to
> > > have an ACK from Paul Moore, who is the SELinux maintainer.
> >
> > In the past I've pulled patches such as this (new LSM hook, with only
> > a SELinux implementation of the new hook) in via the selinux/next tree
> > after the other LSMs have ACK'd the new hook.  This helps limit merge
> > problems with other SELinux changes and allows us (the SELinux folks)
> > to include it in the ongoing testing that we do during the -rcX
> > releases.
> >
> > So Anna, if you or anyone else on the NFS side of the house want to
> > add your ACKs/REVIEWs/etc. please do so as I don't like merging
> > patches that cross subsystem boundaries without having all the
> > associated ACKs.  Casey, James, and other LSM folks please do the
> > same.
>
> Sure:
> Acked-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
>
> Are you also going to take patch 3/3 that uses the new hook, or should
> that go through the NFS tree? Patch 2/3 is a cleanup that can go
> through the NFS tree.

Generally when patches are posted as patchsets I would apply the whole
patchset assuming they patches were all good, however it does seem
like patch 2/3 is not strictly related to the other two?  That said,
as long as your ACK applies to all three patches in the patchset I
have no problem applying all of them to the selinux/next tree once
some of the other LSM maintainers provide their ACKs (while there may
only a SELinux implementation of the hook at the moment, we need to
make sure the other LSMs are okay with the basic hook concept).

Also, did the v4 posting only include patch 1/3?  I see v3 postings
for the other two patches, but the only v4 patch I see is 1/3 ... ?
Olga Kornievskaia March 12, 2021, 10:34 p.m. UTC | #6
On Fri, Mar 12, 2021 at 4:55 PM Paul Moore <paul@paul-moore.com> wrote:
>
> On Fri, Mar 12, 2021 at 10:45 AM Anna Schumaker
> <anna.schumaker@netapp.com> wrote:
> > On Thu, Mar 4, 2021 at 8:34 PM Paul Moore <paul@paul-moore.com> wrote:
> > > On Tue, Mar 2, 2021 at 10:53 PM Casey Schaufler <casey@schaufler-ca.com> wrote:
> > > > On 3/2/2021 10:20 AM, Anna Schumaker wrote:
> > > > > Hi Casey,
> > > > >
> > > > > On Fri, Feb 26, 2021 at 10:40 PM Olga Kornievskaia
> > > > > <olga.kornievskaia@gmail.com> wrote:
> > > > >> From: Olga Kornievskaia <kolga@netapp.com>
> > > > >>
> > > > >> Add a new hook that takes an existing super block and a new mount
> > > > >> with new options and determines if new options confict with an
> > > > >> existing mount or not.
> > > > >>
> > > > >> A filesystem can use this new hook to determine if it can share
> > > > >> the an existing superblock with a new superblock for the new mount.
> > > > >>
> > > > >> Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
> > > > > Do you have any other thoughts on this patch? I'm also wondering how
> > > > > you want to handle sending it upstream.
> > > >
> > > > James Morris is the maintainer for the security sub-system,
> > > > so you'll want to send this through him. He will want you to
> > > > have an ACK from Paul Moore, who is the SELinux maintainer.
> > >
> > > In the past I've pulled patches such as this (new LSM hook, with only
> > > a SELinux implementation of the new hook) in via the selinux/next tree
> > > after the other LSMs have ACK'd the new hook.  This helps limit merge
> > > problems with other SELinux changes and allows us (the SELinux folks)
> > > to include it in the ongoing testing that we do during the -rcX
> > > releases.
> > >
> > > So Anna, if you or anyone else on the NFS side of the house want to
> > > add your ACKs/REVIEWs/etc. please do so as I don't like merging
> > > patches that cross subsystem boundaries without having all the
> > > associated ACKs.  Casey, James, and other LSM folks please do the
> > > same.
> >
> > Sure:
> > Acked-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
> >
> > Are you also going to take patch 3/3 that uses the new hook, or should
> > that go through the NFS tree? Patch 2/3 is a cleanup that can go
> > through the NFS tree.
>
> Generally when patches are posted as patchsets I would apply the whole
> patchset assuming they patches were all good, however it does seem
> like patch 2/3 is not strictly related to the other two?  That said,
> as long as your ACK applies to all three patches in the patchset I
> have no problem applying all of them to the selinux/next tree once
> some of the other LSM maintainers provide their ACKs (while there may
> only a SELinux implementation of the hook at the moment, we need to
> make sure the other LSMs are okay with the basic hook concept).
>
> Also, did the v4 posting only include patch 1/3?  I see v3 postings
> for the other two patches, but the only v4 patch I see is 1/3 ... ?

I didn't not repost patches that didn't change.

>
> --
> paul moore
> www.paul-moore.com
Paul Moore March 15, 2021, 1:43 a.m. UTC | #7
On Fri, Mar 12, 2021 at 5:35 PM Olga Kornievskaia
<olga.kornievskaia@gmail.com> wrote:
> On Fri, Mar 12, 2021 at 4:55 PM Paul Moore <paul@paul-moore.com> wrote:
> >
> > On Fri, Mar 12, 2021 at 10:45 AM Anna Schumaker
> > <anna.schumaker@netapp.com> wrote:
> > > On Thu, Mar 4, 2021 at 8:34 PM Paul Moore <paul@paul-moore.com> wrote:
> > > > On Tue, Mar 2, 2021 at 10:53 PM Casey Schaufler <casey@schaufler-ca.com> wrote:
> > > > > On 3/2/2021 10:20 AM, Anna Schumaker wrote:
> > > > > > Hi Casey,
> > > > > >
> > > > > > On Fri, Feb 26, 2021 at 10:40 PM Olga Kornievskaia
> > > > > > <olga.kornievskaia@gmail.com> wrote:
> > > > > >> From: Olga Kornievskaia <kolga@netapp.com>
> > > > > >>
> > > > > >> Add a new hook that takes an existing super block and a new mount
> > > > > >> with new options and determines if new options confict with an
> > > > > >> existing mount or not.
> > > > > >>
> > > > > >> A filesystem can use this new hook to determine if it can share
> > > > > >> the an existing superblock with a new superblock for the new mount.
> > > > > >>
> > > > > >> Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
> > > > > > Do you have any other thoughts on this patch? I'm also wondering how
> > > > > > you want to handle sending it upstream.
> > > > >
> > > > > James Morris is the maintainer for the security sub-system,
> > > > > so you'll want to send this through him. He will want you to
> > > > > have an ACK from Paul Moore, who is the SELinux maintainer.
> > > >
> > > > In the past I've pulled patches such as this (new LSM hook, with only
> > > > a SELinux implementation of the new hook) in via the selinux/next tree
> > > > after the other LSMs have ACK'd the new hook.  This helps limit merge
> > > > problems with other SELinux changes and allows us (the SELinux folks)
> > > > to include it in the ongoing testing that we do during the -rcX
> > > > releases.
> > > >
> > > > So Anna, if you or anyone else on the NFS side of the house want to
> > > > add your ACKs/REVIEWs/etc. please do so as I don't like merging
> > > > patches that cross subsystem boundaries without having all the
> > > > associated ACKs.  Casey, James, and other LSM folks please do the
> > > > same.
> > >
> > > Sure:
> > > Acked-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
> > >
> > > Are you also going to take patch 3/3 that uses the new hook, or should
> > > that go through the NFS tree? Patch 2/3 is a cleanup that can go
> > > through the NFS tree.
> >
> > Generally when patches are posted as patchsets I would apply the whole
> > patchset assuming they patches were all good, however it does seem
> > like patch 2/3 is not strictly related to the other two?  That said,
> > as long as your ACK applies to all three patches in the patchset I
> > have no problem applying all of them to the selinux/next tree once
> > some of the other LSM maintainers provide their ACKs (while there may
> > only a SELinux implementation of the hook at the moment, we need to
> > make sure the other LSMs are okay with the basic hook concept).
> >
> > Also, did the v4 posting only include patch 1/3?  I see v3 postings
> > for the other two patches, but the only v4 patch I see is 1/3 ... ?
>
> I didn't not repost patches that didn't change.

Okay, so I'm guessing that means path 2/3 and 3/3 didn't change?

While I suppose there are cases where people do not do this, it has
been my experience that if someone posts a patchset and some portion
of the patchset changes, due to feedback or other factors, the entire
patchset is reposted under the new version number.  If nothing else
this helps ensure people are always looking at the latest draft of a
particular patch instead of having to dig through the list to
determine which patch is the most recent.
Olga Kornievskaia March 15, 2021, 3:30 p.m. UTC | #8
On Sun, Mar 14, 2021 at 9:44 PM Paul Moore <paul@paul-moore.com> wrote:
>
> On Fri, Mar 12, 2021 at 5:35 PM Olga Kornievskaia
> <olga.kornievskaia@gmail.com> wrote:
> > On Fri, Mar 12, 2021 at 4:55 PM Paul Moore <paul@paul-moore.com> wrote:
> > >
> > > On Fri, Mar 12, 2021 at 10:45 AM Anna Schumaker
> > > <anna.schumaker@netapp.com> wrote:
> > > > On Thu, Mar 4, 2021 at 8:34 PM Paul Moore <paul@paul-moore.com> wrote:
> > > > > On Tue, Mar 2, 2021 at 10:53 PM Casey Schaufler <casey@schaufler-ca.com> wrote:
> > > > > > On 3/2/2021 10:20 AM, Anna Schumaker wrote:
> > > > > > > Hi Casey,
> > > > > > >
> > > > > > > On Fri, Feb 26, 2021 at 10:40 PM Olga Kornievskaia
> > > > > > > <olga.kornievskaia@gmail.com> wrote:
> > > > > > >> From: Olga Kornievskaia <kolga@netapp.com>
> > > > > > >>
> > > > > > >> Add a new hook that takes an existing super block and a new mount
> > > > > > >> with new options and determines if new options confict with an
> > > > > > >> existing mount or not.
> > > > > > >>
> > > > > > >> A filesystem can use this new hook to determine if it can share
> > > > > > >> the an existing superblock with a new superblock for the new mount.
> > > > > > >>
> > > > > > >> Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
> > > > > > > Do you have any other thoughts on this patch? I'm also wondering how
> > > > > > > you want to handle sending it upstream.
> > > > > >
> > > > > > James Morris is the maintainer for the security sub-system,
> > > > > > so you'll want to send this through him. He will want you to
> > > > > > have an ACK from Paul Moore, who is the SELinux maintainer.
> > > > >
> > > > > In the past I've pulled patches such as this (new LSM hook, with only
> > > > > a SELinux implementation of the new hook) in via the selinux/next tree
> > > > > after the other LSMs have ACK'd the new hook.  This helps limit merge
> > > > > problems with other SELinux changes and allows us (the SELinux folks)
> > > > > to include it in the ongoing testing that we do during the -rcX
> > > > > releases.
> > > > >
> > > > > So Anna, if you or anyone else on the NFS side of the house want to
> > > > > add your ACKs/REVIEWs/etc. please do so as I don't like merging
> > > > > patches that cross subsystem boundaries without having all the
> > > > > associated ACKs.  Casey, James, and other LSM folks please do the
> > > > > same.
> > > >
> > > > Sure:
> > > > Acked-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
> > > >
> > > > Are you also going to take patch 3/3 that uses the new hook, or should
> > > > that go through the NFS tree? Patch 2/3 is a cleanup that can go
> > > > through the NFS tree.
> > >
> > > Generally when patches are posted as patchsets I would apply the whole
> > > patchset assuming they patches were all good, however it does seem
> > > like patch 2/3 is not strictly related to the other two?  That said,
> > > as long as your ACK applies to all three patches in the patchset I
> > > have no problem applying all of them to the selinux/next tree once
> > > some of the other LSM maintainers provide their ACKs (while there may
> > > only a SELinux implementation of the hook at the moment, we need to
> > > make sure the other LSMs are okay with the basic hook concept).
> > >
> > > Also, did the v4 posting only include patch 1/3?  I see v3 postings
> > > for the other two patches, but the only v4 patch I see is 1/3 ... ?
> >
> > I didn't not repost patches that didn't change.
>
> Okay, so I'm guessing that means path 2/3 and 3/3 didn't change?
>
> While I suppose there are cases where people do not do this, it has
> been my experience that if someone posts a patchset and some portion
> of the patchset changes, due to feedback or other factors, the entire
> patchset is reposted under the new version number.  If nothing else
> this helps ensure people are always looking at the latest draft of a
> particular patch instead of having to dig through the list to
> determine which patch is the most recent.

Correct, patches 2&3 didn't change and selinux patch generated several
iterations. Would you like me to repost a series? I'm not sure what
I'm supposed to do at this point.

>
> --
> paul moore
> www.paul-moore.com
Paul Moore March 15, 2021, 4:15 p.m. UTC | #9
On Mon, Mar 15, 2021 at 11:31 AM Olga Kornievskaia
<olga.kornievskaia@gmail.com> wrote:
> On Sun, Mar 14, 2021 at 9:44 PM Paul Moore <paul@paul-moore.com> wrote:
> > On Fri, Mar 12, 2021 at 5:35 PM Olga Kornievskaia
> > <olga.kornievskaia@gmail.com> wrote:
> > > On Fri, Mar 12, 2021 at 4:55 PM Paul Moore <paul@paul-moore.com> wrote:
> > > >
> > > > On Fri, Mar 12, 2021 at 10:45 AM Anna Schumaker
> > > > <anna.schumaker@netapp.com> wrote:
> > > > > On Thu, Mar 4, 2021 at 8:34 PM Paul Moore <paul@paul-moore.com> wrote:
> > > > > > On Tue, Mar 2, 2021 at 10:53 PM Casey Schaufler <casey@schaufler-ca.com> wrote:
> > > > > > > On 3/2/2021 10:20 AM, Anna Schumaker wrote:
> > > > > > > > Hi Casey,
> > > > > > > >
> > > > > > > > On Fri, Feb 26, 2021 at 10:40 PM Olga Kornievskaia
> > > > > > > > <olga.kornievskaia@gmail.com> wrote:
> > > > > > > >> From: Olga Kornievskaia <kolga@netapp.com>
> > > > > > > >>
> > > > > > > >> Add a new hook that takes an existing super block and a new mount
> > > > > > > >> with new options and determines if new options confict with an
> > > > > > > >> existing mount or not.
> > > > > > > >>
> > > > > > > >> A filesystem can use this new hook to determine if it can share
> > > > > > > >> the an existing superblock with a new superblock for the new mount.
> > > > > > > >>
> > > > > > > >> Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
> > > > > > > > Do you have any other thoughts on this patch? I'm also wondering how
> > > > > > > > you want to handle sending it upstream.
> > > > > > >
> > > > > > > James Morris is the maintainer for the security sub-system,
> > > > > > > so you'll want to send this through him. He will want you to
> > > > > > > have an ACK from Paul Moore, who is the SELinux maintainer.
> > > > > >
> > > > > > In the past I've pulled patches such as this (new LSM hook, with only
> > > > > > a SELinux implementation of the new hook) in via the selinux/next tree
> > > > > > after the other LSMs have ACK'd the new hook.  This helps limit merge
> > > > > > problems with other SELinux changes and allows us (the SELinux folks)
> > > > > > to include it in the ongoing testing that we do during the -rcX
> > > > > > releases.
> > > > > >
> > > > > > So Anna, if you or anyone else on the NFS side of the house want to
> > > > > > add your ACKs/REVIEWs/etc. please do so as I don't like merging
> > > > > > patches that cross subsystem boundaries without having all the
> > > > > > associated ACKs.  Casey, James, and other LSM folks please do the
> > > > > > same.
> > > > >
> > > > > Sure:
> > > > > Acked-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
> > > > >
> > > > > Are you also going to take patch 3/3 that uses the new hook, or should
> > > > > that go through the NFS tree? Patch 2/3 is a cleanup that can go
> > > > > through the NFS tree.
> > > >
> > > > Generally when patches are posted as patchsets I would apply the whole
> > > > patchset assuming they patches were all good, however it does seem
> > > > like patch 2/3 is not strictly related to the other two?  That said,
> > > > as long as your ACK applies to all three patches in the patchset I
> > > > have no problem applying all of them to the selinux/next tree once
> > > > some of the other LSM maintainers provide their ACKs (while there may
> > > > only a SELinux implementation of the hook at the moment, we need to
> > > > make sure the other LSMs are okay with the basic hook concept).
> > > >
> > > > Also, did the v4 posting only include patch 1/3?  I see v3 postings
> > > > for the other two patches, but the only v4 patch I see is 1/3 ... ?
> > >
> > > I didn't not repost patches that didn't change.
> >
> > Okay, so I'm guessing that means path 2/3 and 3/3 didn't change?
> >
> > While I suppose there are cases where people do not do this, it has
> > been my experience that if someone posts a patchset and some portion
> > of the patchset changes, due to feedback or other factors, the entire
> > patchset is reposted under the new version number.  If nothing else
> > this helps ensure people are always looking at the latest draft of a
> > particular patch instead of having to dig through the list to
> > determine which patch is the most recent.
>
> Correct, patches 2&3 didn't change and selinux patch generated several
> iterations. Would you like me to repost a series? I'm not sure what
> I'm supposed to do at this point.

As long as we are clear that the latest draft of patch 1/3 is to be
taken from the v4 patch{set} and patches 2/3 and 3/3 are to be taken
from v3 of the patchset I don't think you need to do anything further.
The important bit is for the other LSM folks to ACK the new hook; if I
don't see anything from them, either positive or negative, I'll merge
it towards the end of this week or early next.
Paul Moore March 18, 2021, 7:12 p.m. UTC | #10
On Mon, Mar 15, 2021 at 12:15 PM Paul Moore <paul@paul-moore.com> wrote:
> As long as we are clear that the latest draft of patch 1/3 is to be
> taken from the v4 patch{set} and patches 2/3 and 3/3 are to be taken
> from v3 of the patchset I don't think you need to do anything further.
> The important bit is for the other LSM folks to ACK the new hook; if I
> don't see anything from them, either positive or negative, I'll merge
> it towards the end of this week or early next.

LSM folks, this is a reminder that if you want to object you've got
until Monday morning to do so :)
Casey Schaufler March 18, 2021, 7:21 p.m. UTC | #11
On 3/18/2021 12:12 PM, Paul Moore wrote:
> On Mon, Mar 15, 2021 at 12:15 PM Paul Moore <paul@paul-moore.com> wrote:
>> As long as we are clear that the latest draft of patch 1/3 is to be
>> taken from the v4 patch{set} and patches 2/3 and 3/3 are to be taken
>> from v3 of the patchset I don't think you need to do anything further.
>> The important bit is for the other LSM folks to ACK the new hook; if I
>> don't see anything from them, either positive or negative, I'll merge
>> it towards the end of this week or early next.
> LSM folks, this is a reminder that if you want to object you've got
> until Monday morning to do so :)

No objections on my part. My comments have been addressed.
James Morris March 18, 2021, 10:49 p.m. UTC | #12
On Thu, 18 Mar 2021, Paul Moore wrote:

> On Mon, Mar 15, 2021 at 12:15 PM Paul Moore <paul@paul-moore.com> wrote:
> > As long as we are clear that the latest draft of patch 1/3 is to be
> > taken from the v4 patch{set} and patches 2/3 and 3/3 are to be taken
> > from v3 of the patchset I don't think you need to do anything further.
> > The important bit is for the other LSM folks to ACK the new hook; if I
> > don't see anything from them, either positive or negative, I'll merge
> > it towards the end of this week or early next.
> 
> LSM folks, this is a reminder that if you want to object you've got
> until Monday morning to do so :)

I'm unclear on whether a new v5 patchset was being posted -- I assume not?
Olga Kornievskaia March 18, 2021, 10:59 p.m. UTC | #13
On Thu, Mar 18, 2021 at 6:51 PM James Morris <jmorris@namei.org> wrote:
>
> On Thu, 18 Mar 2021, Paul Moore wrote:
>
> > On Mon, Mar 15, 2021 at 12:15 PM Paul Moore <paul@paul-moore.com> wrote:
> > > As long as we are clear that the latest draft of patch 1/3 is to be
> > > taken from the v4 patch{set} and patches 2/3 and 3/3 are to be taken
> > > from v3 of the patchset I don't think you need to do anything further.
> > > The important bit is for the other LSM folks to ACK the new hook; if I
> > > don't see anything from them, either positive or negative, I'll merge
> > > it towards the end of this week or early next.
> >
> > LSM folks, this is a reminder that if you want to object you've got
> > until Monday morning to do so :)
>
> I'm unclear on whether a new v5 patchset was being posted -- I assume not?

v4 addressed all the existing concerns/comments that were made. no new
version is planned unless somebody else has any more comments.

>
> --
> James Morris
> <jmorris@namei.org>
>
Paul Moore March 22, 2021, 6:56 p.m. UTC | #14
On Thu, Mar 18, 2021 at 3:12 PM Paul Moore <paul@paul-moore.com> wrote:
> On Mon, Mar 15, 2021 at 12:15 PM Paul Moore <paul@paul-moore.com> wrote:
> > As long as we are clear that the latest draft of patch 1/3 is to be
> > taken from the v4 patch{set} and patches 2/3 and 3/3 are to be taken
> > from v3 of the patchset I don't think you need to do anything further.
> > The important bit is for the other LSM folks to ACK the new hook; if I
> > don't see anything from them, either positive or negative, I'll merge
> > it towards the end of this week or early next.
>
> LSM folks, this is a reminder that if you want to object you've got
> until Monday morning to do so :)

Time is up, I just merged it into selinux/next ;)

Thanks everyone!
diff mbox series

Patch

diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index 7aaa753b8608..1b12a5266a51 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -62,6 +62,7 @@  LSM_HOOK(int, 0, sb_alloc_security, struct super_block *sb)
 LSM_HOOK(void, LSM_RET_VOID, sb_free_security, struct super_block *sb)
 LSM_HOOK(void, LSM_RET_VOID, sb_free_mnt_opts, void *mnt_opts)
 LSM_HOOK(int, 0, sb_eat_lsm_opts, char *orig, void **mnt_opts)
+LSM_HOOK(int, 0, sb_mnt_opts_compat, struct super_block *sb, void *mnt_opts)
 LSM_HOOK(int, 0, sb_remount, struct super_block *sb, void *mnt_opts)
 LSM_HOOK(int, 0, sb_kern_mount, struct super_block *sb)
 LSM_HOOK(int, 0, sb_show_options, struct seq_file *m, struct super_block *sb)
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index a19adef1f088..0de8eb2ea547 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -142,6 +142,12 @@ 
  *	@orig the original mount data copied from userspace.
  *	@copy copied data which will be passed to the security module.
  *	Returns 0 if the copy was successful.
+ * @sb_mnt_opts_compat:
+ * 	Determine if the new mount options in @mnt_opts are allowed given
+ * 	the existing mounted filesystem at @sb.
+ *	@sb superblock being compared
+ *	@mnt_opts new mount options
+ *	Return 0 if options are compatible.
  * @sb_remount:
  *	Extracts security system specific mount options and verifies no changes
  *	are being made to those options.
diff --git a/include/linux/security.h b/include/linux/security.h
index c35ea0ffccd9..50db3d5d1608 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -291,6 +291,7 @@  int security_sb_alloc(struct super_block *sb);
 void security_sb_free(struct super_block *sb);
 void security_free_mnt_opts(void **mnt_opts);
 int security_sb_eat_lsm_opts(char *options, void **mnt_opts);
+int security_sb_mnt_opts_compat(struct super_block *sb, void *mnt_opts);
 int security_sb_remount(struct super_block *sb, void *mnt_opts);
 int security_sb_kern_mount(struct super_block *sb);
 int security_sb_show_options(struct seq_file *m, struct super_block *sb);
@@ -635,6 +636,13 @@  static inline int security_sb_remount(struct super_block *sb,
 	return 0;
 }
 
+static inline int security_sb_mnt_opts_compat(struct super_block *sb,
+					      void *mnt_opts)
+{
+	return 0;
+}
+
+
 static inline int security_sb_kern_mount(struct super_block *sb)
 {
 	return 0;
diff --git a/security/security.c b/security/security.c
index 7b09cfbae94f..56cf5563efde 100644
--- a/security/security.c
+++ b/security/security.c
@@ -890,6 +890,13 @@  int security_sb_eat_lsm_opts(char *options, void **mnt_opts)
 }
 EXPORT_SYMBOL(security_sb_eat_lsm_opts);
 
+int security_sb_mnt_opts_compat(struct super_block *sb,
+				void *mnt_opts)
+{
+	return call_int_hook(sb_mnt_opts_compat, 0, sb, mnt_opts);
+}
+EXPORT_SYMBOL(security_sb_mnt_opts_compat);
+
 int security_sb_remount(struct super_block *sb,
 			void *mnt_opts)
 {
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 644b17ec9e63..afee3a222a0e 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2656,6 +2656,61 @@  static int selinux_sb_eat_lsm_opts(char *options, void **mnt_opts)
 	return rc;
 }
 
+static int selinux_sb_mnt_opts_compat(struct super_block *sb, void *mnt_opts)
+{
+	struct selinux_mnt_opts *opts = mnt_opts;
+	struct superblock_security_struct *sbsec = sb->s_security;
+	u32 sid;
+	int rc;
+
+	/*
+	 * Superblock not initialized (i.e. no options) - reject if any
+	 * options specified, otherwise accept.
+	 */
+	if (!(sbsec->flags & SE_SBINITIALIZED))
+		return opts ? 1 : 0;
+
+	/*
+	 * Superblock initialized and no options specified - reject if
+	 * superblock has any options set, otherwise accept.
+	 */
+	if (!opts)
+		return (sbsec->flags & SE_MNTMASK) ? 1 : 0;
+
+	if (opts->fscontext) {
+		rc = parse_sid(sb, opts->fscontext, &sid);
+		if (rc)
+			return 1;
+		if (bad_option(sbsec, FSCONTEXT_MNT, sbsec->sid, sid))
+			return 1;
+	}
+	if (opts->context) {
+		rc = parse_sid(sb, opts->context, &sid);
+		if (rc)
+			return 1;
+		if (bad_option(sbsec, CONTEXT_MNT, sbsec->mntpoint_sid, sid))
+			return 1;
+	}
+	if (opts->rootcontext) {
+		struct inode_security_struct *root_isec;
+
+		root_isec = backing_inode_security(sb->s_root);
+		rc = parse_sid(sb, opts->rootcontext, &sid);
+		if (rc)
+			return 1;
+		if (bad_option(sbsec, ROOTCONTEXT_MNT, root_isec->sid, sid))
+			return 1;
+	}
+	if (opts->defcontext) {
+		rc = parse_sid(sb, opts->defcontext, &sid);
+		if (rc)
+			return 1;
+		if (bad_option(sbsec, DEFCONTEXT_MNT, sbsec->def_sid, sid))
+			return 1;
+	}
+	return 0;
+}
+
 static int selinux_sb_remount(struct super_block *sb, void *mnt_opts)
 {
 	struct selinux_mnt_opts *opts = mnt_opts;
@@ -6984,6 +7039,7 @@  static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
 
 	LSM_HOOK_INIT(sb_free_security, selinux_sb_free_security),
 	LSM_HOOK_INIT(sb_free_mnt_opts, selinux_free_mnt_opts),
+	LSM_HOOK_INIT(sb_mnt_opts_compat, selinux_sb_mnt_opts_compat),
 	LSM_HOOK_INIT(sb_remount, selinux_sb_remount),
 	LSM_HOOK_INIT(sb_kern_mount, selinux_sb_kern_mount),
 	LSM_HOOK_INIT(sb_show_options, selinux_sb_show_options),