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Message-ID: <6ee7e769-ce91-a6cc-378b-f206e04d112a@huawei.com>
Date: Fri, 8 Jul 2022 17:14:25 +0300
From: "Konstantin Meskhidze (A)" <konstantin.meskhidze@...wei.com>
To: Mickaël Salaün <mic@...ikod.net>
CC: <willemdebruijn.kernel@...il.com>,
<linux-security-module@...r.kernel.org>, <netdev@...r.kernel.org>,
<netfilter-devel@...r.kernel.org>, <yusongping@...wei.com>,
<anton.sirazetdinov@...wei.com>
Subject: Re: [PATCH v6 02/17] landlock: refactors landlock_find/insert_rule
7/8/2022 4:59 PM, Mickaël Salaün пишет:
>
> On 08/07/2022 15:10, Konstantin Meskhidze (A) wrote:
>>
>>
>> 7/7/2022 7:44 PM, Mickaël Salaün пишет:
>>>
>>> On 21/06/2022 10:22, Konstantin Meskhidze wrote:
>>>> Adds a new object union to support a socket port
>>>> rule type. Refactors landlock_insert_rule() and
>>>> landlock_find_rule() to support coming network
>>>> modifications. Now adding or searching a rule
>>>> in a ruleset depends on a rule_type argument
>>>> provided in refactored functions mentioned above.
>>>>
>>>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@...wei.com>
>>>> ---
>>>>
>>>> Changes since v5:
>>>> * Formats code with clang-format-14.
>>>>
>>>> Changes since v4:
>>>> * Refactors insert_rule() and create_rule() functions by deleting
>>>> rule_type from their arguments list, it helps to reduce useless code.
>>>>
>>>> Changes since v3:
>>>> * Splits commit.
>>>> * Refactors landlock_insert_rule and landlock_find_rule functions.
>>>> * Rename new_ruleset->root_inode.
>>>>
>>>> ---
>>>> security/landlock/fs.c | 7 ++-
>>>> security/landlock/ruleset.c | 105 ++++++++++++++++++++++++++----------
>>>> security/landlock/ruleset.h | 27 +++++-----
>>>> 3 files changed, 96 insertions(+), 43 deletions(-)
>>>>
>>>> diff --git a/security/landlock/fs.c b/security/landlock/fs.c
>>>> index e6da08ed99d1..46aedc2a05a8 100644
>>>> --- a/security/landlock/fs.c
>>>> +++ b/security/landlock/fs.c
>>>> @@ -173,7 +173,8 @@ int landlock_append_fs_rule(struct
>>>> landlock_ruleset *const ruleset,
>>>> if (IS_ERR(object))
>>>> return PTR_ERR(object);
>>>> mutex_lock(&ruleset->lock);
>>>> - err = landlock_insert_rule(ruleset, object, access_rights);
>>>> + err = landlock_insert_rule(ruleset, object, 0, access_rights,
>>>> + LANDLOCK_RULE_PATH_BENEATH);
>>>> mutex_unlock(&ruleset->lock);
>>>> /*
>>>> * No need to check for an error because landlock_insert_rule()
>>>> @@ -204,7 +205,9 @@ find_rule(const struct landlock_ruleset *const
>>>> domain,
>>>> inode = d_backing_inode(dentry);
>>>> rcu_read_lock();
>>>> rule = landlock_find_rule(
>>>> - domain, rcu_dereference(landlock_inode(inode)->object));
>>>> + domain,
>>>> + (uintptr_t)rcu_dereference(landlock_inode(inode)->object),
>>>> + LANDLOCK_RULE_PATH_BENEATH);
>>>> rcu_read_unlock();
>>>> return rule;
>>>> }
>>>> diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
>>>> index a3fd58d01f09..5f13f8a12aee 100644
>>>> --- a/security/landlock/ruleset.c
>>>> +++ b/security/landlock/ruleset.c
>>>> @@ -35,7 +35,7 @@ static struct landlock_ruleset
>>>> *create_ruleset(const u32 num_layers)
>>>> return ERR_PTR(-ENOMEM);
>>>> refcount_set(&new_ruleset->usage, 1);
>>>> mutex_init(&new_ruleset->lock);
>>>> - new_ruleset->root = RB_ROOT;
>>>> + new_ruleset->root_inode = RB_ROOT;
>>>> new_ruleset->num_layers = num_layers;
>>>> /*
>>>> * hierarchy = NULL
>>>> @@ -69,7 +69,8 @@ static void build_check_rule(void)
>>>> }
>>>>
>>>> static struct landlock_rule *
>>>> -create_rule(struct landlock_object *const object,
>>>> +create_rule(struct landlock_object *const object_ptr,
>>>> + const uintptr_t object_data,
>>>> const struct landlock_layer (*const layers)[], const u32
>>>> num_layers,
>>>> const struct landlock_layer *const new_layer)
>>>> {
>>>> @@ -90,8 +91,15 @@ create_rule(struct landlock_object *const object,
>>>> if (!new_rule)
>>>> return ERR_PTR(-ENOMEM);
>>>> RB_CLEAR_NODE(&new_rule->node);
>>>> - landlock_get_object(object);
>>>> - new_rule->object = object;
>>>> +
>>>> + if (object_ptr) {
>>>> + landlock_get_object(object_ptr);
>>>> + new_rule->object.ptr = object_ptr;
>>>> + } else if (object_ptr && object_data) {
>>>
>>> Something is wrong with this second check: else + object_ptr?
>>
>> Sorry. Do you mean logical error here? I got your point.
>> You are right!
>>
>> I think it must be refactored like this:
>>
>> if (object_ptr && !object_data) {
>> landlock_get_object(object_ptr);
>> new_rule->object.ptr = object_ptr;
>> } else if (object_ptr && object_data) {
>> ...
>> }
>
> There is indeed a logical error but this doesn't fix everything. Please
> include my previous suggestion instead.
>
By the way, in the next commits I have fixed this logic error.
Anyway I will refactor this one also. Thanks.
>
>> Plus, I will add a test for this case.
>
> That would be great but I don't think this code is reachable from user
> space. I think that would require kunit but I may be missing something.
> How would you test this?
You are correct. I checked it. It's impossible to reach this line from
userpace (insert both object_ptr and object_data). But create_rule()
must be used carefuly by other developers (if any in future). Do you
think if its possible to have some internal kernel tests that could
handle this issue?
> .
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