netdev - Re: [PATCH v10 02/13] landlock: Allow filesystem layout changes for domains without such rule type

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Date:   Thu, 20 Apr 2023 14:42:17 +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>, <yusongping@...wei.com>,
        <artem.kuzin@...wei.com>
Subject: Re: [PATCH v10 02/13] landlock: Allow filesystem layout changes for
 domains without such rule type



4/16/2023 7:09 PM, Mickaël Salaün пишет:
> 
> On 23/03/2023 09:52, Konstantin Meskhidze wrote:
>> From: Mickaël Salaün <mic@...ikod.net>
>> 
>> Allow mount point and root directory changes when there is no filesystem
>> rule tied to the current Landlock domain.  This doesn't change anything
>> for now because a domain must have at least a (filesystem) rule, but
>> this will change when other rule types will come.  For instance, a
>> domain only restricting the network should have no impact on filesystem
>> restrictions.
>> 
>> Add a new get_current_fs_domain() helper to quickly check filesystem
>> rule existence for all filesystem LSM hooks.
>> 
>> Remove unnecessary inlining.
>> 
>> Signed-off-by: Mickaël Salaün <mic@...ikod.net>
>> ---
>> 
>> Changes since v9:
>> * Refactors documentaion landlock.rst.
>> * Changes ACCESS_FS_INITIALLY_DENIED constant
>> to LANDLOCK_ACCESS_FS_INITIALLY_DENIED.
>> * Gets rid of unnecessary masking of access_dom in
>> get_raw_handled_fs_accesses() function.
>> 
>> Changes since v8:
>> * Refactors get_handled_fs_accesses().
>> * Adds landlock_get_raw_fs_access_mask() helper.
>> 
>> ---
>>   Documentation/userspace-api/landlock.rst |  6 +-
>>   security/landlock/fs.c                   | 78 ++++++++++++------------
>>   security/landlock/ruleset.h              | 25 +++++++-
>>   security/landlock/syscalls.c             |  6 +-
>>   4 files changed, 68 insertions(+), 47 deletions(-)
>> 
> 
> [...]
> 
>> diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c
>> index 71aca7f990bc..d35cd5d304db 100644
>> --- a/security/landlock/syscalls.c
>> +++ b/security/landlock/syscalls.c
>> @@ -310,6 +310,7 @@ SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd,
>>   	struct path path;
>>   	struct landlock_ruleset *ruleset;
>>   	int res, err;
>> +	access_mask_t mask;
>> 
>>   	if (!landlock_initialized)
>>   		return -EOPNOTSUPP;
>> @@ -348,9 +349,8 @@ SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd,
>>   	 * Checks that allowed_access matches the @ruleset constraints
>>   	 * (ruleset->access_masks[0] is automatically upgraded to 64-bits).
>>   	 */
>> -	if ((path_beneath_attr.allowed_access |
>> -	     landlock_get_fs_access_mask(ruleset, 0)) !=
>> -	    landlock_get_fs_access_mask(ruleset, 0)) {
>> +	mask = landlock_get_raw_fs_access_mask(ruleset, 0);
>> +	if ((path_beneath_attr.allowed_access | mask) != mask) {
> 
> This hunk can be moved to the previous patch (i.e. mask = …). This patch
> should only contains the new landlock_get_raw_fs_access_mask() call.
> 

  Sorry. Did not get this tip. Please can you explain what do you mean here?
> 
>>   		err = -EINVAL;
>>   		goto out_put_ruleset;
>>   	}
>> --
>> 2.25.1
>> 
> .