Unverified Commit 7a11275c authored by Konstantin Meskhidze's avatar Konstantin Meskhidze Committed by Mickaël Salaün
Browse files

landlock: Refactor layer helpers 



Add a new key_type argument to the landlock_init_layer_masks() helper.
Add a masks_array_size argument to the landlock_unmask_layers() helper.
These modifications support implementing new rule types in the next
Landlock versions.

Signed-off-by: default avatarKonstantin Meskhidze <konstantin.meskhidze@huawei.com>
Link: https://lore.kernel.org/r/20231026014751.414649-7-konstantin.meskhidze@huawei.com


Signed-off-by: default avatarMickaël Salaün <mic@digikod.net>
parent 0e741011

security/landlock/fs.c

+24 −19
Original line number Diff line number Diff line
@@ -442,20 +442,22 @@ static bool is_access_to_paths_allowed( 
	}



	if (unlikely(dentry_child1)) {

		landlock_unmask_layers(find_rule(domain, dentry_child1),

		landlock_unmask_layers(

			find_rule(domain, dentry_child1),

			landlock_init_layer_masks(

				domain, LANDLOCK_MASK_ACCESS_FS,

					       &_layer_masks_child1),

				       &_layer_masks_child1);

				&_layer_masks_child1, LANDLOCK_KEY_INODE),

			&_layer_masks_child1, ARRAY_SIZE(_layer_masks_child1));

		layer_masks_child1 = &_layer_masks_child1;

		child1_is_directory = d_is_dir(dentry_child1);

	}

	if (unlikely(dentry_child2)) {

		landlock_unmask_layers(find_rule(domain, dentry_child2),

		landlock_unmask_layers(

			find_rule(domain, dentry_child2),

			landlock_init_layer_masks(

				domain, LANDLOCK_MASK_ACCESS_FS,

					       &_layer_masks_child2),

				       &_layer_masks_child2);

				&_layer_masks_child2, LANDLOCK_KEY_INODE),

			&_layer_masks_child2, ARRAY_SIZE(_layer_masks_child2));

		layer_masks_child2 = &_layer_masks_child2;

		child2_is_directory = d_is_dir(dentry_child2);

	}
@@ -508,14 +510,15 @@ static bool is_access_to_paths_allowed( 


		rule = find_rule(domain, walker_path.dentry);

		allowed_parent1 = landlock_unmask_layers(

			rule, access_masked_parent1, layer_masks_parent1);

			rule, access_masked_parent1, layer_masks_parent1,

			ARRAY_SIZE(*layer_masks_parent1));

		allowed_parent2 = landlock_unmask_layers(

			rule, access_masked_parent2, layer_masks_parent2);

			rule, access_masked_parent2, layer_masks_parent2,

			ARRAY_SIZE(*layer_masks_parent2));



		/* Stops when a rule from each layer grants access. */

		if (allowed_parent1 && allowed_parent2)

			break;



jump_up:

		if (walker_path.dentry == walker_path.mnt->mnt_root) {

			if (follow_up(&walker_path)) {
@@ -554,8 +557,8 @@ static inline int check_access_path(const struct landlock_ruleset *const domain, 
{

	layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_FS] = {};



	access_request =

		landlock_init_layer_masks(domain, access_request, &layer_masks);

	access_request = landlock_init_layer_masks(

		domain, access_request, &layer_masks, LANDLOCK_KEY_INODE);

	if (is_access_to_paths_allowed(domain, path, access_request,

				       &layer_masks, NULL, 0, NULL, NULL))

		return 0;
@@ -641,7 +644,8 @@ static bool collect_domain_accesses( 
		return true;



	access_dom = landlock_init_layer_masks(domain, LANDLOCK_MASK_ACCESS_FS,

					       layer_masks_dom);

					       layer_masks_dom,

					       LANDLOCK_KEY_INODE);



	dget(dir);

	while (true) {
@@ -649,7 +653,8 @@ static bool collect_domain_accesses( 


		/* Gets all layers allowing all domain accesses. */

		if (landlock_unmask_layers(find_rule(domain, dir), access_dom,

					   layer_masks_dom)) {

					   layer_masks_dom,

					   ARRAY_SIZE(*layer_masks_dom))) {

			/*

			 * Stops when all handled accesses are allowed by at

			 * least one rule in each layer.
@@ -764,7 +769,7 @@ static int current_check_refer_path(struct dentry *const old_dentry, 
		 */

		access_request_parent1 = landlock_init_layer_masks(

			dom, access_request_parent1 | access_request_parent2,

			&layer_masks_parent1);

			&layer_masks_parent1, LANDLOCK_KEY_INODE);

		if (is_access_to_paths_allowed(

			    dom, new_dir, access_request_parent1,

			    &layer_masks_parent1, NULL, 0, NULL, NULL))
@@ -1140,7 +1145,7 @@ static int hook_file_open(struct file *const file) 
	if (is_access_to_paths_allowed(

		    dom, &file->f_path,

		    landlock_init_layer_masks(dom, full_access_request,

					      &layer_masks),

					      &layer_masks, LANDLOCK_KEY_INODE),

		    &layer_masks, NULL, 0, NULL, NULL)) {

		allowed_access = full_access_request;

	} else {

security/landlock/ruleset.c

+33 −15
Original line number Diff line number Diff line
@@ -573,14 +573,15 @@ landlock_find_rule(const struct landlock_ruleset *const ruleset, 
/*

 * @layer_masks is read and may be updated according to the access request and

 * the matching rule.

 * @masks_array_size must be equal to ARRAY_SIZE(*layer_masks).

 *

 * Returns true if the request is allowed (i.e. relevant layer masks for the

 * request are empty).

 */

bool landlock_unmask_layers(

	const struct landlock_rule *const rule,

bool landlock_unmask_layers(const struct landlock_rule *const rule,

			    const access_mask_t access_request,

	layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS])

			    layer_mask_t (*const layer_masks)[],

			    const size_t masks_array_size)

{

	size_t layer_level;
@@ -612,8 +613,7 @@ bool landlock_unmask_layers( 
		 * requested access.

		 */

		is_empty = true;

		for_each_set_bit(access_bit, &access_req,

				 ARRAY_SIZE(*layer_masks)) {

		for_each_set_bit(access_bit, &access_req, masks_array_size) {

			if (layer->access & BIT_ULL(access_bit))

				(*layer_masks)[access_bit] &= ~layer_bit;

			is_empty = is_empty && !(*layer_masks)[access_bit];
@@ -624,6 +624,10 @@ bool landlock_unmask_layers( 
	return false;

}



typedef access_mask_t

get_access_mask_t(const struct landlock_ruleset *const ruleset,

		  const u16 layer_level);



/**

 * landlock_init_layer_masks - Initialize layer masks from an access request

 *
@@ -633,19 +637,34 @@ bool landlock_unmask_layers( 
 * @domain: The domain that defines the current restrictions.

 * @access_request: The requested access rights to check.

 * @layer_masks: The layer masks to populate.

 * @key_type: The key type to switch between access masks of different types.

 *

 * Returns: An access mask where each access right bit is set which is handled

 * in any of the active layers in @domain.

 */

access_mask_t landlock_init_layer_masks(

	const struct landlock_ruleset *const domain,

access_mask_t

landlock_init_layer_masks(const struct landlock_ruleset *const domain,

			  const access_mask_t access_request,

	layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS])

			  layer_mask_t (*const layer_masks)[],

			  const enum landlock_key_type key_type)

{

	access_mask_t handled_accesses = 0;

	size_t layer_level;

	size_t layer_level, num_access;

	get_access_mask_t *get_access_mask;



	switch (key_type) {

	case LANDLOCK_KEY_INODE:

		get_access_mask = landlock_get_fs_access_mask;

		num_access = LANDLOCK_NUM_ACCESS_FS;

		break;

	default:

		WARN_ON_ONCE(1);

		return 0;

	}



	memset(layer_masks, 0,

	       array_size(sizeof((*layer_masks)[0]), num_access));



	memset(layer_masks, 0, sizeof(*layer_masks));

	/* An empty access request can happen because of O_WRONLY | O_RDWR. */

	if (!access_request)

		return 0;
@@ -655,10 +674,9 @@ access_mask_t landlock_init_layer_masks( 
		const unsigned long access_req = access_request;

		unsigned long access_bit;



		for_each_set_bit(access_bit, &access_req,

				 ARRAY_SIZE(*layer_masks)) {

		for_each_set_bit(access_bit, &access_req, num_access) {

			if (BIT_ULL(access_bit) &

			    landlock_get_fs_access_mask(domain, layer_level)) {

			    get_access_mask(domain, layer_level)) {

				(*layer_masks)[access_bit] |=

					BIT_ULL(layer_level);

				handled_accesses |= BIT_ULL(access_bit);

security/landlock/ruleset.h

+9 −8
Original line number Diff line number Diff line
@@ -267,14 +267,15 @@ landlock_get_fs_access_mask(const struct landlock_ruleset *const ruleset, 
	       LANDLOCK_ACCESS_FS_INITIALLY_DENIED;

}



bool landlock_unmask_layers(

	const struct landlock_rule *const rule,

bool landlock_unmask_layers(const struct landlock_rule *const rule,

			    const access_mask_t access_request,

	layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS]);

			    layer_mask_t (*const layer_masks)[],

			    const size_t masks_array_size);



access_mask_t landlock_init_layer_masks(

	const struct landlock_ruleset *const domain,

access_mask_t

landlock_init_layer_masks(const struct landlock_ruleset *const domain,

			  const access_mask_t access_request,

	layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS]);

			  layer_mask_t (*const layer_masks)[],

			  const enum landlock_key_type key_type);



#endif /* _SECURITY_LANDLOCK_RULESET_H */