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

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Date:   Sun, 16 Apr 2023 18:09:08 +0200
From:   Mickaël Salaün <mic@...ikod.net>
To:     Konstantin Meskhidze <konstantin.meskhidze@...wei.com>
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


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.


>   		err = -EINVAL;
>   		goto out_put_ruleset;
>   	}
> --
> 2.25.1
>