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Message-ID: <Zy-qROSRm1rb_pww@google.com>
Date: Sat, 9 Nov 2024 19:30:28 +0100
From: "Günther Noack" <gnoack@...gle.com>
To: "Mickaël Salaün" <mic@...ikod.net>
Cc: Mikhail Ivanov <ivanov.mikhail1@...wei-partners.com>,
Konstantin Meskhidze <konstantin.meskhidze@...wei.com>, Paul Moore <paul@...l-moore.com>,
Tahera Fahimi <fahimitahera@...il.com>, linux-kernel@...r.kernel.org,
linux-security-module@...r.kernel.org
Subject: Re: [PATCH v4 3/3] landlock: Optimize scope enforcement
On Sat, Nov 09, 2024 at 12:08:56PM +0100, Mickaël Salaün wrote:
> Do not walk through the domain hierarchy when the required scope is not
> supported by this domain. This is the same approach as for filesystem
> and network restrictions.
>
> Cc: Günther Noack <gnoack@...gle.com>
> Cc: Mikhail Ivanov <ivanov.mikhail1@...wei-partners.com>
> Cc: Tahera Fahimi <fahimitahera@...il.com>
> Signed-off-by: Mickaël Salaün <mic@...ikod.net>
> Link: https://lore.kernel.org/r/20241109110856.222842-4-mic@digikod.net
> ---
>
> Changes since v2:
> * Make the unix_scope variable global to the file and remove
> previous get_current_unix_scope_domain().
> ---
> security/landlock/task.c | 18 +++++++++++++++---
> 1 file changed, 15 insertions(+), 3 deletions(-)
>
> diff --git a/security/landlock/task.c b/security/landlock/task.c
> index 4acbd7c40eee..dc7dab78392e 100644
> --- a/security/landlock/task.c
> +++ b/security/landlock/task.c
> @@ -204,12 +204,17 @@ static bool is_abstract_socket(struct sock *const sock)
> return false;
> }
>
> +static const struct access_masks unix_scope = {
> + .scope = LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET,
> +};
Optional nit: You could probably inline these two struct access_masks values
into the respective functions where they are used. (But it's just a minor code
style matter IMHO; both ways are fine.)
> +
> static int hook_unix_stream_connect(struct sock *const sock,
> struct sock *const other,
> struct sock *const newsk)
> {
> const struct landlock_ruleset *const dom =
> - landlock_get_current_domain();
> + landlock_get_applicable_domain(landlock_get_current_domain(),
> + unix_scope);
>
> /* Quick return for non-landlocked tasks. */
> if (!dom)
> @@ -225,7 +230,8 @@ static int hook_unix_may_send(struct socket *const sock,
> struct socket *const other)
> {
> const struct landlock_ruleset *const dom =
> - landlock_get_current_domain();
> + landlock_get_applicable_domain(landlock_get_current_domain(),
> + unix_scope);
>
> if (!dom)
> return 0;
> @@ -243,6 +249,10 @@ static int hook_unix_may_send(struct socket *const sock,
> return 0;
> }
>
> +static const struct access_masks signal_scope = {
> + .scope = LANDLOCK_SCOPE_SIGNAL,
> +};
> +
> static int hook_task_kill(struct task_struct *const p,
> struct kernel_siginfo *const info, const int sig,
> const struct cred *const cred)
> @@ -256,6 +266,7 @@ static int hook_task_kill(struct task_struct *const p,
> } else {
> dom = landlock_get_current_domain();
> }
> + dom = landlock_get_applicable_domain(dom, signal_scope);
>
> /* Quick return for non-landlocked tasks. */
> if (!dom)
> @@ -279,7 +290,8 @@ static int hook_file_send_sigiotask(struct task_struct *tsk,
>
> /* Lock already held by send_sigio() and send_sigurg(). */
> lockdep_assert_held(&fown->lock);
> - dom = landlock_file(fown->file)->fown_domain;
> + dom = landlock_get_applicable_domain(
> + landlock_file(fown->file)->fown_domain, signal_scope);
>
> /* Quick return for unowned socket. */
> if (!dom)
> --
> 2.47.0
>
Reviewed-by: Günther Noack <gnoack@...gle.com>
Looks good!
—Günther
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