Unverified Commit 13fc6455 authored by Konstantin Meskhidze's avatar Konstantin Meskhidze Committed by Mickaël Salaün
Browse files

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: default avatarKonstantin Meskhidze <konstantin.meskhidze@huawei.com>
Link: https://lore.kernel.org/r/20231026014751.414649-2-konstantin.meskhidze@huawei.com


Signed-off-by: default avatarMickaël Salaün <mic@digikod.net>
parent 05d3ef8b

security/landlock/fs.c

+5 −5
Original line number Diff line number Diff line
@@ -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);

security/landlock/limits.h

+1 −0
Original line number Diff line number Diff line
@@ -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 */

security/landlock/ruleset.c

+9 −8
Original line number Diff line number Diff line
@@ -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;

security/landlock/ruleset.h

+31 −4
Original line number Diff line number Diff line
@@ -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 */

security/landlock/syscalls.c

+4 −3
Original line number Diff line number Diff line
@@ -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;

	}