landlock: Make ruleset's access masks more generic

Rename ruleset's access masks and modify it's type to access_masks_t
to support network type rules in following commits. Add filesystem
helper functions to add and get filesystem mask.

Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>
Link: https://lore.kernel.org/r/20231026014751.414649-2-konstantin.meskhidze@huawei.com
Signed-off-by: Mickaël Salaün <mic@digikod.net>

diff --git a/security/landlock/fs.c b/security/landlock/fs.c
index 1c0c198..6953801 100644 (file)
--- a/security/landlock/fs.c
+++ b/security/landlock/fs.c
@@ -178,9 +178,9 @@ int landlock_append_fs_rule(struct landlock_ruleset *const ruleset,
                return -EINVAL;
 
        /* Transforms relative access rights to absolute ones. */
-       access_rights |=
-               LANDLOCK_MASK_ACCESS_FS &
-               ~(ruleset->fs_access_masks[0] | ACCESS_INITIALLY_DENIED);
+       access_rights |= LANDLOCK_MASK_ACCESS_FS &
+                        ~(landlock_get_fs_access_mask(ruleset, 0) |
+                          ACCESS_INITIALLY_DENIED);
        object = get_inode_object(d_backing_inode(path->dentry));
        if (IS_ERR(object))
                return PTR_ERR(object);
@@ -294,7 +294,7 @@ get_handled_accesses(const struct landlock_ruleset *const domain)
        size_t layer_level;
 
        for (layer_level = 0; layer_level < domain->num_layers; layer_level++)
-               access_dom |= domain->fs_access_masks[layer_level];
+               access_dom |= landlock_get_fs_access_mask(domain, layer_level);
        return access_dom & LANDLOCK_MASK_ACCESS_FS;
 }
 
@@ -336,7 +336,7 @@ init_layer_masks(const struct landlock_ruleset *const domain,
                         * access rights.
                         */
                        if (BIT_ULL(access_bit) &
-                           (domain->fs_access_masks[layer_level] |
+                           (landlock_get_fs_access_mask(domain, layer_level) |
                             ACCESS_INITIALLY_DENIED)) {
                                (*layer_masks)[access_bit] |=
                                        BIT_ULL(layer_level);

diff --git a/security/landlock/limits.h b/security/landlock/limits.h
index 82288f0..bafb3b8 100644 (file)
--- a/security/landlock/limits.h
+++ b/security/landlock/limits.h
@@ -21,6 +21,7 @@
 #define LANDLOCK_LAST_ACCESS_FS                LANDLOCK_ACCESS_FS_TRUNCATE
 #define LANDLOCK_MASK_ACCESS_FS                ((LANDLOCK_LAST_ACCESS_FS << 1) - 1)
 #define LANDLOCK_NUM_ACCESS_FS         __const_hweight64(LANDLOCK_MASK_ACCESS_FS)
+#define LANDLOCK_SHIFT_ACCESS_FS       0
 
 /* clang-format on */
 

diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
index 996484f..1f3188b 100644 (file)
--- a/security/landlock/ruleset.c
+++ b/security/landlock/ruleset.c
@@ -29,7 +29,7 @@ static struct landlock_ruleset *create_ruleset(const u32 num_layers)
        struct landlock_ruleset *new_ruleset;
 
        new_ruleset =
-               kzalloc(struct_size(new_ruleset, fs_access_masks, num_layers),
+               kzalloc(struct_size(new_ruleset, access_masks, num_layers),
                        GFP_KERNEL_ACCOUNT);
        if (!new_ruleset)
                return ERR_PTR(-ENOMEM);
@@ -40,7 +40,7 @@ static struct landlock_ruleset *create_ruleset(const u32 num_layers)
        /*
         * hierarchy = NULL
         * num_rules = 0
-        * fs_access_masks[] = 0
+        * access_masks[] = 0
         */
        return new_ruleset;
 }
@@ -55,7 +55,7 @@ landlock_create_ruleset(const access_mask_t fs_access_mask)
                return ERR_PTR(-ENOMSG);
        new_ruleset = create_ruleset(1);
        if (!IS_ERR(new_ruleset))
-               new_ruleset->fs_access_masks[0] = fs_access_mask;
+               landlock_add_fs_access_mask(new_ruleset, fs_access_mask, 0);
        return new_ruleset;
 }
 
@@ -117,11 +117,12 @@ static void build_check_ruleset(void)
                .num_rules = ~0,
                .num_layers = ~0,
        };
-       typeof(ruleset.fs_access_masks[0]) fs_access_mask = ~0;
+       typeof(ruleset.access_masks[0]) access_masks = ~0;
 
        BUILD_BUG_ON(ruleset.num_rules < LANDLOCK_MAX_NUM_RULES);
        BUILD_BUG_ON(ruleset.num_layers < LANDLOCK_MAX_NUM_LAYERS);
-       BUILD_BUG_ON(fs_access_mask < LANDLOCK_MASK_ACCESS_FS);
+       BUILD_BUG_ON(access_masks <
+                    (LANDLOCK_MASK_ACCESS_FS << LANDLOCK_SHIFT_ACCESS_FS));
 }
 
 /**
@@ -281,7 +282,7 @@ static int merge_ruleset(struct landlock_ruleset *const dst,
                err = -EINVAL;
                goto out_unlock;
        }
-       dst->fs_access_masks[dst->num_layers - 1] = src->fs_access_masks[0];
+       dst->access_masks[dst->num_layers - 1] = src->access_masks[0];
 
        /* Merges the @src tree. */
        rbtree_postorder_for_each_entry_safe(walker_rule, next_rule, &src->root,
@@ -340,8 +341,8 @@ static int inherit_ruleset(struct landlock_ruleset *const parent,
                goto out_unlock;
        }
        /* Copies the parent layer stack and leaves a space for the new layer. */
-       memcpy(child->fs_access_masks, parent->fs_access_masks,
-              flex_array_size(parent, fs_access_masks, parent->num_layers));
+       memcpy(child->access_masks, parent->access_masks,
+              flex_array_size(parent, access_masks, parent->num_layers));
 
        if (WARN_ON_ONCE(!parent->hierarchy)) {
                err = -EINVAL;

diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h
index 55b1df8..8c99c32 100644 (file)
--- a/security/landlock/ruleset.h
+++ b/security/landlock/ruleset.h
@@ -25,6 +25,11 @@ static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_FS);
 /* Makes sure for_each_set_bit() and for_each_clear_bit() calls are OK. */
 static_assert(sizeof(unsigned long) >= sizeof(access_mask_t));
 
+/* Ruleset access masks. */
+typedef u16 access_masks_t;
+/* Makes sure all ruleset access rights can be stored. */
+static_assert(BITS_PER_TYPE(access_masks_t) >= LANDLOCK_NUM_ACCESS_FS);
+
 typedef u16 layer_mask_t;
 /* Makes sure all layers can be checked. */
 static_assert(BITS_PER_TYPE(layer_mask_t) >= LANDLOCK_MAX_NUM_LAYERS);
@@ -110,7 +115,7 @@ struct landlock_ruleset {
                 * section.  This is only used by
                 * landlock_put_ruleset_deferred() when @usage reaches zero.
                 * The fields @lock, @usage, @num_rules, @num_layers and
-                * @fs_access_masks are then unused.
+                * @access_masks are then unused.
                 */
                struct work_struct work_free;
                struct {
@@ -137,7 +142,7 @@ struct landlock_ruleset {
                         */
                        u32 num_layers;
                        /**
-                        * @fs_access_masks: Contains the subset of filesystem
+                        * @access_masks: Contains the subset of filesystem
                         * actions that are restricted by a ruleset.  A domain
                         * saves all layers of merged rulesets in a stack
                         * (FAM), starting from the first layer to the last
@@ -148,13 +153,13 @@ struct landlock_ruleset {
                         * layers are set once and never changed for the
                         * lifetime of the ruleset.
                         */
-                       access_mask_t fs_access_masks[];
+                       access_masks_t access_masks[];
                };
        };
 };
 
 struct landlock_ruleset *
-landlock_create_ruleset(const access_mask_t fs_access_mask);
+landlock_create_ruleset(const access_mask_t access_mask);
 
 void landlock_put_ruleset(struct landlock_ruleset *const ruleset);
 void landlock_put_ruleset_deferred(struct landlock_ruleset *const ruleset);
@@ -177,4 +182,26 @@ static inline void landlock_get_ruleset(struct landlock_ruleset *const ruleset)
                refcount_inc(&ruleset->usage);
 }
 
+static inline void
+landlock_add_fs_access_mask(struct landlock_ruleset *const ruleset,
+                           const access_mask_t fs_access_mask,
+                           const u16 layer_level)
+{
+       access_mask_t fs_mask = fs_access_mask & LANDLOCK_MASK_ACCESS_FS;
+
+       /* Should already be checked in sys_landlock_create_ruleset(). */
+       WARN_ON_ONCE(fs_access_mask != fs_mask);
+       ruleset->access_masks[layer_level] |=
+               (fs_mask << LANDLOCK_SHIFT_ACCESS_FS);
+}
+
+static inline access_mask_t
+landlock_get_fs_access_mask(const struct landlock_ruleset *const ruleset,
+                           const u16 layer_level)
+{
+       return (ruleset->access_masks[layer_level] >>
+               LANDLOCK_SHIFT_ACCESS_FS) &
+              LANDLOCK_MASK_ACCESS_FS;
+}
+
 #endif /* _SECURITY_LANDLOCK_RULESET_H */

diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c
index 245cc65..7ec6bbe 100644 (file)
--- 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;
@@ -346,10 +347,10 @@ SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd,
        }
        /*
         * Checks that allowed_access matches the @ruleset constraints
-        * (ruleset->fs_access_masks[0] is automatically upgraded to 64-bits).
+        * (ruleset->access_masks[0] is automatically upgraded to 64-bits).
         */
-       if ((path_beneath_attr.allowed_access | ruleset->fs_access_masks[0]) !=
-           ruleset->fs_access_masks[0]) {
+       mask = landlock_get_fs_access_mask(ruleset, 0);
+       if ((path_beneath_attr.allowed_access | mask) != mask) {
                err = -EINVAL;
                goto out_put_ruleset;
        }