Date:   Fri, 2 Dec 2022 06:14:43 +0300
From:   "Konstantin Meskhidze (A)" <konstantin.meskhidze@...wei.com>
To:     Mickaël Salaün <mic@...ikod.net>
CC:     <willemdebruijn.kernel@...il.com>, <gnoack3000@...il.com>,
        <linux-security-module@...r.kernel.org>, <netdev@...r.kernel.org>,
        <netfilter-devel@...r.kernel.org>, <artem.kuzin@...wei.com>,
        <linux-doc@...r.kernel.org>
Subject: Re: [PATCH v8 12/12] landlock: Document Landlock's network support



11/28/2022 11:26 PM, Mickaël Salaün пишет:
> 
> On 28/11/2022 07:44, Konstantin Meskhidze (A) wrote:
>> 
>> 
>> 11/17/2022 9:44 PM, Mickaël Salaün пишет:
>>>
>>> On 21/10/2022 17:26, Konstantin Meskhidze wrote:
>>>> Describes network access rules for TCP sockets. Adds network access
>>>> example in the tutorial. Points out AF_UNSPEC socket family behaviour.
>>>> Adds kernel configuration support for network.
>>>>
>>>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@...wei.com>
>>>> ---
>>>>
>>>> Changes since v7:
>>>> * Fixes documentaion logic errors and typos as Mickaёl suggested:
>>>> https://lore.kernel.org/netdev/9f354862-2bc3-39ea-92fd-53803d9bbc21@digikod.net/
>>>>
>>>> Changes since v6:
>>>> * Adds network support documentaion.
>>>>
>>>> ---
>>>>    Documentation/userspace-api/landlock.rst | 72 +++++++++++++++++++-----
>>>>    1 file changed, 59 insertions(+), 13 deletions(-)
>>>>
>>>> diff --git a/Documentation/userspace-api/landlock.rst b/Documentation/userspace-api/landlock.rst
>>>> index d8cd8cd9ce25..d0610ec9ce05 100644
>>>> --- a/Documentation/userspace-api/landlock.rst
>>>> +++ b/Documentation/userspace-api/landlock.rst
>>>> @@ -11,10 +11,10 @@ Landlock: unprivileged access control
>>>>    :Date: October 2022
>>>>
>>>>    The goal of Landlock is to enable to restrict ambient rights (e.g. global
>>>> -filesystem access) for a set of processes.  Because Landlock is a stackable
>>>> -LSM, it makes possible to create safe security sandboxes as new security layers
>>>> -in addition to the existing system-wide access-controls. This kind of sandbox
>>>> -is expected to help mitigate the security impact of bugs or
>>>> +filesystem or network access) for a set of processes.  Because Landlock
>>>> +is a stackable LSM, it makes possible to create safe security sandboxes as new
>>>> +security layers in addition to the existing system-wide access-controls. This
>>>> +kind of sandbox is expected to help mitigate the security impact of bugs or
>>>>    unexpected/malicious behaviors in user space applications.  Landlock empowers
>>>>    any process, including unprivileged ones, to securely restrict themselves.
>>>>
>>>> @@ -30,18 +30,20 @@ Landlock rules
>>>>
>>>>    A Landlock rule describes an action on an object.  An object is currently a
>>>>    file hierarchy, and the related filesystem actions are defined with `access
>>>> -rights`_.  A set of rules is aggregated in a ruleset, which can then restrict
>>>> -the thread enforcing it, and its future children.
>>>> +rights`_.  Since ABI version 4 a port data appears with related network actions
>>>> +for TCP socket families.  A set of rules is aggregated in a ruleset, which
>>>> +can then restrict the thread enforcing it, and its future children.
>>>>
>>>>    Defining and enforcing a security policy
>>>>    ----------------------------------------
>>>>
>>>>    We first need to define the ruleset that will contain our rules.  For this
>>>>    example, the ruleset will contain rules that only allow read actions, but write
>>>> -actions will be denied.  The ruleset then needs to handle both of these kind of
>>>> +actions will be denied. The ruleset then needs to handle both of these kind of
>>>>    actions.  This is required for backward and forward compatibility (i.e. the
>>>>    kernel and user space may not know each other's supported restrictions), hence
>>>> -the need to be explicit about the denied-by-default access rights.
>>>> +the need to be explicit about the denied-by-default access rights.  Also ruleset
>>>> +will have network rules for specific ports, so it should handle network actions.
>>>>
>>>>    .. code-block:: c
>>>>
>>>> @@ -62,6 +64,9 @@ the need to be explicit about the denied-by-default access rights.
>>>>                LANDLOCK_ACCESS_FS_MAKE_SYM |
>>>>                LANDLOCK_ACCESS_FS_REFER |
>>>>                LANDLOCK_ACCESS_FS_TRUNCATE,
>>>> +        .handled_access_net =
>>>> +            LANDLOCK_ACCESS_NET_BIND_TCP |
>>>> +            LANDLOCK_ACCESS_NET_CONNECT_TCP,
>>>>        };
>>>>
>>>>    Because we may not know on which kernel version an application will be
>>>> @@ -70,14 +75,18 @@ should try to protect users as much as possible whatever the kernel they are
>>>>    using.  To avoid binary enforcement (i.e. either all security features or
>>>>    none), we can leverage a dedicated Landlock command to get the current version
>>>>    of the Landlock ABI and adapt the handled accesses.  Let's check if we should
>>>> -remove the ``LANDLOCK_ACCESS_FS_REFER`` or ``LANDLOCK_ACCESS_FS_TRUNCATE``
>>>> -access rights, which are only supported starting with the second and third
>>>> -version of the ABI.
>>>> +remove the `LANDLOCK_ACCESS_FS_REFER` or `LANDLOCK_ACCESS_FS_TRUNCATE` or
>>>> +network access rights, which are only supported starting with the second,
>>>
>>> This is a bad rebase.
>> 
>>     Sorry. Did not get it.
> 
> This hunk (and maybe others) changes unrelated things (e.g. back quotes).

   Ok. Got it. Thanks.
> 
> 
>>>
>>>
>>>> +third and fourth version of the ABI.
>>>>
>>>>    .. code-block:: c
>>>>
>>>>        int abi;
>>>>
>>>> +    #define ACCESS_NET_BIND_CONNECT ( \
>>>> +    LANDLOCK_ACCESS_NET_BIND_TCP | \
>>>> +    LANDLOCK_ACCESS_NET_CONNECT_TCP)
>>>
>>> Please add a 4-spaces prefix for these two lines.
>> 
>>     Like this??
>> 	#define ACCESS_NET_BIND_CONNECT ( \
>>               LANDLOCK_ACCESS_NET_BIND_TCP | \
>>               LANDLOCK_ACCESS_NET_CONNECT_TCP)
> 
> Like for other indentations in the documentation (e.g. ruleset_attr
> definition):
> 
> #define ACCESS_NET_BIND_CONNECT ( \
>       LANDLOCK_ACCESS_NET_BIND_TCP | \
>       LANDLOCK_ACCESS_NET_CONNECT_TCP)

  Ok. Will be fixed.
> .

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