diff options
| author | Günther Noack <gnoack3000@gmail.com> | 2026-03-27 17:48:30 +0100 |
|---|---|---|
| committer | Mickaël Salaün <mic@digikod.net> | 2026-04-07 18:51:07 +0200 |
| commit | a46e32db1fb7acac49a35773345d4bcf343847f5 (patch) | |
| tree | 57c2371e0f8cc6614a5df559188691764d1c51e3 /security | |
| parent | ae97330d1bd6a97646c2842d117577236cb40913 (diff) | |
| download | linux-next-history-a46e32db1fb7acac49a35773345d4bcf343847f5.tar.gz | |
landlock: Clarify BUILD_BUG_ON check in scoping logic
The BUILD_BUG_ON check in domain_is_scoped() and
unmask_scoped_access() should check that the loop that counts down
client_layer finishes. We therefore check that the numbers
LANDLOCK_MAX_NUM_LAYERS-1 and -1 are both representable by that
integer. If they are representable, the numbers in between are
representable too, and the loop finishes.
Signed-off-by: Günther Noack <gnoack3000@gmail.com>
Link: https://lore.kernel.org/r/20260327164838.38231-6-gnoack3000@gmail.com
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Diffstat (limited to 'security')
| -rw-r--r-- | security/landlock/fs.c | 9 | ||||
| -rw-r--r-- | security/landlock/task.c | 9 |
2 files changed, 12 insertions, 6 deletions
diff --git a/security/landlock/fs.c b/security/landlock/fs.c index fcf69b3d734d6..c1ecfe2390326 100644 --- a/security/landlock/fs.c +++ b/security/landlock/fs.c @@ -1595,10 +1595,13 @@ static void unmask_scoped_access(const struct landlock_ruleset *const client, return; /* - * client_layer must be a signed integer with greater capacity - * than client->num_layers to ensure the following loop stops. + * client_layer must be able to represent all numbers from + * LANDLOCK_MAX_NUM_LAYERS - 1 to -1 for the loop below to terminate. + * (It must be large enough, and it must be signed.) */ - BUILD_BUG_ON(sizeof(client_layer) > sizeof(client->num_layers)); + BUILD_BUG_ON(!is_signed_type(typeof(client_layer))); + BUILD_BUG_ON(LANDLOCK_MAX_NUM_LAYERS - 1 > + type_max(typeof(client_layer))); client_layer = client->num_layers - 1; client_walker = client->hierarchy; diff --git a/security/landlock/task.c b/security/landlock/task.c index f2dbdebf2770a..6d46042132ce1 100644 --- a/security/landlock/task.c +++ b/security/landlock/task.c @@ -191,10 +191,13 @@ static bool domain_is_scoped(const struct landlock_ruleset *const client, client_layer = client->num_layers - 1; client_walker = client->hierarchy; /* - * client_layer must be a signed integer with greater capacity - * than client->num_layers to ensure the following loop stops. + * client_layer must be able to represent all numbers from + * LANDLOCK_MAX_NUM_LAYERS - 1 to -1 for the loop below to terminate. + * (It must be large enough, and it must be signed.) */ - BUILD_BUG_ON(sizeof(client_layer) > sizeof(client->num_layers)); + BUILD_BUG_ON(!is_signed_type(typeof(client_layer))); + BUILD_BUG_ON(LANDLOCK_MAX_NUM_LAYERS - 1 > + type_max(typeof(client_layer))); server_layer = server ? (server->num_layers - 1) : -1; server_walker = server ? server->hierarchy : NULL; |