diff mbox series

[v5,04/15] landlock: helper functions refactoring

Message ID 20220516152038.39594-5-konstantin.meskhidze@huawei.com (mailing list archive)
State New
Headers show
Series Network support for Landlock | expand

Commit Message

Konstantin Meskhidze (A) May 16, 2022, 3:20 p.m. UTC
Unmask_layers(), init_layer_masks() and
get_handled_accesses() helper functions move to
ruleset.c and rule_type argument is added.
This modification supports implementing new rule
types into next landlock versions.

Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>
---

Changes since v3:
* Splits commit.
* Refactoring landlock_unmask_layers functions.

Changes since v4:
* Refactoring init_layer_masks(), get_handled_accesses()
and unmask_layers() functions to support multiple rule types.
* Refactoring landlock_get_fs_access_mask() function with
LANDLOCK_MASK_ACCESS_FS mask.

---
 security/landlock/fs.c      | 158 ++++++++----------------------------
 security/landlock/ruleset.c | 152 +++++++++++++++++++++++++++++++---
 security/landlock/ruleset.h |  17 +++-
 3 files changed, 192 insertions(+), 135 deletions(-)

--
2.25.1

Comments

Mickaël Salaün May 16, 2022, 5:14 p.m. UTC | #1
On 16/05/2022 17:20, Konstantin Meskhidze wrote:
> Unmask_layers(), init_layer_masks() and
> get_handled_accesses() helper functions move to
> ruleset.c and rule_type argument is added.
> This modification supports implementing new rule
> types into next landlock versions.
> 
> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>
> ---
> 
> Changes since v3:
> * Splits commit.
> * Refactoring landlock_unmask_layers functions.
> 

Please sort changes in antichronological order. It is easier to look at 
the first lines to get the last changes.

> Changes since v4:
> * Refactoring init_layer_masks(), get_handled_accesses()
> and unmask_layers() functions to support multiple rule types.
> * Refactoring landlock_get_fs_access_mask() function with
> LANDLOCK_MASK_ACCESS_FS mask. >
> ---
>   security/landlock/fs.c      | 158 ++++++++----------------------------
>   security/landlock/ruleset.c | 152 +++++++++++++++++++++++++++++++---
>   security/landlock/ruleset.h |  17 +++-
>   3 files changed, 192 insertions(+), 135 deletions(-)
> 
> diff --git a/security/landlock/fs.c b/security/landlock/fs.c
> index 5de24d4dd74c..3506e182b23e 100644
> --- a/security/landlock/fs.c
> +++ b/security/landlock/fs.c
> @@ -211,60 +211,6 @@ find_rule(const struct landlock_ruleset *const domain,
>   	return rule;
>   }
> 
> -/*
> - * @layer_masks is read and may be updated according to the access request and
> - * the matching rule.
> - *
> - * Returns true if the request is allowed (i.e. relevant layer masks for the
> - * request are empty).
> - */
> -static inline bool
> -unmask_layers(const struct landlock_rule *const rule,
> -	      const access_mask_t access_request,
> -	      layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS])

Moving these entire blocks of code make the review/diff impossible. Why 
moving these helpers?

> -{
> -	size_t layer_level;
> -
> -	if (!access_request || !layer_masks)
> -		return true;
> -	if (!rule)
> -		return false;
> -
> -	/*
> -	 * An access is granted if, for each policy layer, at least one rule
> -	 * encountered on the pathwalk grants the requested access,
> -	 * regardless of its position in the layer stack.  We must then check
> -	 * the remaining layers for each inode, from the first added layer to
> -	 * the last one.  When there is multiple requested accesses, for each
> -	 * policy layer, the full set of requested accesses may not be granted
> -	 * by only one rule, but by the union (binary OR) of multiple rules.
> -	 * E.g. /a/b <execute> + /a <read> => /a/b <execute + read>
> -	 */
> -	for (layer_level = 0; layer_level < rule->num_layers; layer_level++) {
> -		const struct landlock_layer *const layer =
> -			&rule->layers[layer_level];
> -		const layer_mask_t layer_bit = BIT_ULL(layer->level - 1);
> -		const unsigned long access_req = access_request;
> -		unsigned long access_bit;
> -		bool is_empty;
> -
> -		/*
> -		 * Records in @layer_masks which layer grants access to each
> -		 * requested access.
> -		 */
> -		is_empty = true;
> -		for_each_set_bit(access_bit, &access_req,
> -				 ARRAY_SIZE(*layer_masks)) {
> -			if (layer->access & BIT_ULL(access_bit))
> -				(*layer_masks)[access_bit] &= ~layer_bit;
> -			is_empty = is_empty && !(*layer_masks)[access_bit];
> -		}
> -		if (is_empty)
> -			return true;
> -	}
> -	return false;
> -}
> -
>   /*
>    * Allows access to pseudo filesystems that will never be mountable (e.g.
>    * sockfs, pipefs), but can still be reachable through
> @@ -277,59 +223,6 @@ static inline bool is_nouser_or_private(const struct dentry *dentry)
>   		unlikely(IS_PRIVATE(d_backing_inode(dentry))));
>   }
> 
> -static inline access_mask_t
> -get_handled_accesses(const struct landlock_ruleset *const domain)
> -{
> -	access_mask_t access_dom = 0;
> -	unsigned long access_bit;
> -
> -	for (access_bit = 0; access_bit < LANDLOCK_NUM_ACCESS_FS;
> -	     access_bit++) {
> -		size_t layer_level;
> -
> -		for (layer_level = 0; layer_level < domain->num_layers;
> -				layer_level++) {
> -			if (landlock_get_fs_access_mask(domain, layer_level) &
> -					BIT_ULL(access_bit)) {
> -				access_dom |= BIT_ULL(access_bit);
> -				break;
> -			}
> -		}
> -	}
> -	return access_dom;
> -}
> -
> -static inline access_mask_t
> -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])
> -{
> -	access_mask_t handled_accesses = 0;
> -	size_t layer_level;
> -
> -	memset(layer_masks, 0, sizeof(*layer_masks));
> -	/* An empty access request can happen because of O_WRONLY | O_RDWR. */
> -	if (!access_request)
> -		return 0;
> -
> -	/* Saves all handled accesses per layer. */
> -	for (layer_level = 0; layer_level < domain->num_layers; layer_level++) {
> -		const unsigned long access_req = access_request;
> -		unsigned long access_bit;
> -
> -		for_each_set_bit(access_bit, &access_req,
> -				ARRAY_SIZE(*layer_masks)) {
> -			if (landlock_get_fs_access_mask(domain, layer_level) &
> -					BIT_ULL(access_bit)) {
> -				(*layer_masks)[access_bit] |=
> -					BIT_ULL(layer_level);
> -				handled_accesses |= BIT_ULL(access_bit);
> -			}
> -		}
> -	}
> -	return handled_accesses;
> -}
> -
>   /*
>    * Check that a destination file hierarchy has more restrictions than a source
>    * file hierarchy.  This is only used for link and rename actions.
> @@ -506,7 +399,8 @@ static int check_access_path_dual(
>   		 * a superset of the meaningful requested accesses).
>   		 */
>   		access_masked_parent1 = access_masked_parent2 =
> -			get_handled_accesses(domain);
> +			get_handled_accesses(domain, LANDLOCK_RULE_PATH_BENEATH,
> +					     LANDLOCK_NUM_ACCESS_FS);
>   		is_dom_check = true;
>   	} else {
>   		if (WARN_ON_ONCE(dentry_child1 || dentry_child2))
> @@ -519,17 +413,25 @@ static int check_access_path_dual(
> 
>   	if (unlikely(dentry_child1)) {
>   		unmask_layers(find_rule(domain, dentry_child1),
> -			      init_layer_masks(domain, LANDLOCK_MASK_ACCESS_FS,
> -					       &_layer_masks_child1),
> -			      &_layer_masks_child1);
> +				init_layer_masks(domain,
> +					LANDLOCK_MASK_ACCESS_FS,
> +					&_layer_masks_child1,
> +					sizeof(_layer_masks_child1),
> +					LANDLOCK_RULE_PATH_BENEATH),
> +				&_layer_masks_child1,
> +				ARRAY_SIZE(_layer_masks_child1));

There is a lot of formatting diff and that makes the review difficult. 
Please format everything with clang-format-14.

>   		layer_masks_child1 = &_layer_masks_child1;
>   		child1_is_directory = d_is_dir(dentry_child1);
>   	}
>   	if (unlikely(dentry_child2)) {
>   		unmask_layers(find_rule(domain, dentry_child2),
> -			      init_layer_masks(domain, LANDLOCK_MASK_ACCESS_FS,
> -					       &_layer_masks_child2),
> -			      &_layer_masks_child2);
> +				init_layer_masks(domain,
> +					LANDLOCK_MASK_ACCESS_FS,
> +					&_layer_masks_child2,
> +					sizeof(_layer_masks_child2),
> +					LANDLOCK_RULE_PATH_BENEATH),
> +				&_layer_masks_child2,
> +				ARRAY_SIZE(_layer_masks_child2));
>   		layer_masks_child2 = &_layer_masks_child2;
>   		child2_is_directory = d_is_dir(dentry_child2);
>   	}
> @@ -582,14 +484,15 @@ static int check_access_path_dual(
> 
>   		rule = find_rule(domain, walker_path.dentry);
>   		allowed_parent1 = unmask_layers(rule, access_masked_parent1,
> -						layer_masks_parent1);
> +				layer_masks_parent1,
> +				ARRAY_SIZE(*layer_masks_parent1));
>   		allowed_parent2 = unmask_layers(rule, access_masked_parent2,
> -						layer_masks_parent2);
> +				layer_masks_parent2,
> +				ARRAY_SIZE(*layer_masks_parent2));
> 
>   		/* Stops when a rule from each layer grants access. */
>   		if (allowed_parent1 && allowed_parent2)
>   			break;
> -

There is no place for such formatting/whitespace patches.


>   jump_up:
>   		if (walker_path.dentry == walker_path.mnt->mnt_root) {
>   			if (follow_up(&walker_path)) {
> @@ -645,7 +548,9 @@ static inline int check_access_path(const struct landlock_ruleset *const domain,
>   {
>   	layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_FS] = {};
> 
> -	access_request = init_layer_masks(domain, access_request, &layer_masks);
> +	access_request = init_layer_masks(domain, access_request,
> +			&layer_masks, sizeof(layer_masks),
> +			LANDLOCK_RULE_PATH_BENEATH);
>   	return check_access_path_dual(domain, path, access_request,
>   				      &layer_masks, NULL, 0, NULL, NULL);
>   }
> @@ -729,7 +634,8 @@ static bool collect_domain_accesses(
>   		return true;
> 
>   	access_dom = init_layer_masks(domain, LANDLOCK_MASK_ACCESS_FS,
> -				      layer_masks_dom);
> +			layer_masks_dom, sizeof(*layer_masks_dom),
> +			LANDLOCK_RULE_PATH_BENEATH);
> 
>   	dget(dir);
>   	while (true) {
> @@ -737,7 +643,8 @@ static bool collect_domain_accesses(
> 
>   		/* Gets all layers allowing all domain accesses. */
>   		if (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.
> @@ -851,9 +758,10 @@ static int current_check_refer_path(struct dentry *const old_dentry,
>   		 * The LANDLOCK_ACCESS_FS_REFER access right is not required
>   		 * for same-directory referer (i.e. no reparenting).
>   		 */
> -		access_request_parent1 = init_layer_masks(
> -			dom, access_request_parent1 | access_request_parent2,
> -			&layer_masks_parent1);
> +		access_request_parent1 = init_layer_masks(dom,
> +				access_request_parent1 | access_request_parent2,
> +				&layer_masks_parent1, sizeof(layer_masks_parent1),
> +				LANDLOCK_RULE_PATH_BENEATH);
>   		return check_access_path_dual(dom, new_dir,
>   					      access_request_parent1,
>   					      &layer_masks_parent1, NULL, 0,
> @@ -861,7 +769,9 @@ static int current_check_refer_path(struct dentry *const old_dentry,
>   	}
> 
>   	/* Backward compatibility: no reparenting support. */
> -	if (!(get_handled_accesses(dom) & LANDLOCK_ACCESS_FS_REFER))
> +	if (!(get_handled_accesses(dom, LANDLOCK_RULE_PATH_BENEATH,
> +				   LANDLOCK_NUM_ACCESS_FS) &
> +						LANDLOCK_ACCESS_FS_REFER))
>   		return -EXDEV;
> 
>   	access_request_parent1 |= LANDLOCK_ACCESS_FS_REFER;
> diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
> index 4b4c9953bb32..c4ed783d655b 100644
> --- a/security/landlock/ruleset.c
> +++ b/security/landlock/ruleset.c
> @@ -233,7 +233,8 @@ static int insert_rule(struct landlock_ruleset *const ruleset,
>   					       &(*layers)[0]);
>   			if (IS_ERR(new_rule))
>   				return PTR_ERR(new_rule);
> -			rb_replace_node(&this->node, &new_rule->node, &ruleset->root_inode);
> +			rb_replace_node(&this->node, &new_rule->node,
> +					&ruleset->root_inode);

This is a pure formatting hunk. :/


>   			free_rule(this, rule_type);
>   			break;
>   		}
> @@ -246,7 +247,8 @@ static int insert_rule(struct landlock_ruleset *const ruleset,
>   		return -E2BIG;
>   	switch (rule_type) {
>   	case LANDLOCK_RULE_PATH_BENEATH:
> -		new_rule = create_rule(object_ptr, 0, layers, num_layers, NULL);
> +		new_rule = create_rule(object_ptr, 0, layers,
> +				       num_layers, NULL);
>   		if (IS_ERR(new_rule))
>   			return PTR_ERR(new_rule);
>   		rb_link_node(&new_rule->node, parent_node, walker_node);
> @@ -281,8 +283,8 @@ int landlock_insert_rule(struct landlock_ruleset *const ruleset,
>   	} };
> 
>   	build_check_layer();
> -	return insert_rule(ruleset, object_ptr, object_data, rule_type, &layers,
> -			   ARRAY_SIZE(layers));
> +	return insert_rule(ruleset, object_ptr, object_data, rule_type,
> +			   &layers, ARRAY_SIZE(layers));
>   }
> 
>   static inline void get_hierarchy(struct landlock_hierarchy *const hierarchy)
> @@ -335,8 +337,9 @@ static int tree_merge(struct landlock_ruleset *const src,
> 
>   		switch (rule_type) {
>   		case LANDLOCK_RULE_PATH_BENEATH:
> -			err = insert_rule(dst, walker_rule->object.ptr, 0, rule_type,
> -					  &layers, ARRAY_SIZE(layers));
> +			err = insert_rule(dst, walker_rule->object.ptr, 0,
> +					  rule_type, &layers,
> +					  ARRAY_SIZE(layers));
>   			break;
>   		}
>   		if (err)
> @@ -433,9 +436,13 @@ static int inherit_ruleset(struct landlock_ruleset *const parent,
>   		err = -EINVAL;
>   		goto out_unlock;
>   	}
> -	/* Copies the parent layer stack and leaves a space for the new layer. */
> +	/*
> +	 * Copies the parent layer stack and leaves a space
> +	 * for the new layer.
> +	 */
>   	memcpy(child->access_masks, parent->access_masks,
> -			flex_array_size(parent, access_masks, parent->num_layers));
> +			flex_array_size(parent, access_masks,
> +					parent->num_layers));
> 
>   	if (WARN_ON_ONCE(!parent->hierarchy)) {
>   		err = -EINVAL;
> @@ -455,8 +462,9 @@ static void free_ruleset(struct landlock_ruleset *const ruleset)
>   	struct landlock_rule *freeme, *next;
> 
>   	might_sleep();
> -	rbtree_postorder_for_each_entry_safe(freeme, next, &ruleset->root_inode,
> -			node)
> +	rbtree_postorder_for_each_entry_safe(freeme, next,
> +					     &ruleset->root_inode,
> +					     node)
>   		free_rule(freeme, LANDLOCK_RULE_PATH_BENEATH);
>   	put_hierarchy(ruleset->hierarchy);
>   	kfree(ruleset);
> @@ -577,3 +585,127 @@ const struct landlock_rule *landlock_find_rule(
>   	}
>   	return NULL;
>   }
> +
> +access_mask_t get_handled_accesses(
> +		const struct landlock_ruleset *const domain,
> +		u16 rule_type, u16 num_access)
> +{
> +	access_mask_t access_dom = 0;
> +	unsigned long access_bit;
> +
> +	switch (rule_type) {
> +	case LANDLOCK_RULE_PATH_BENEATH:
> +		for (access_bit = 0; access_bit < LANDLOCK_NUM_ACCESS_FS;
> +			access_bit++) {
> +			size_t layer_level;
> +
> +			for (layer_level = 0; layer_level < domain->num_layers;
> +					layer_level++) {
> +				if (landlock_get_fs_access_mask(domain,
> +								layer_level) &
> +						BIT_ULL(access_bit)) {
> +					access_dom |= BIT_ULL(access_bit);
> +					break;
> +				}
> +			}
> +		}
> +		break;
> +	default:
> +		break;
> +	}
> +	return access_dom;
> +}
> +
> +/*
> + * @layer_masks is read and may be updated according to the access request and
> + * the matching rule.
> + *
> + * Returns true if the request is allowed (i.e. relevant layer masks for the
> + * request are empty).
> + */
> +bool unmask_layers(const struct landlock_rule *const rule,
> +		const access_mask_t access_request,
> +		layer_mask_t (*const layer_masks)[], size_t masks_array_size)
> +{
> +	size_t layer_level;
> +
> +	if (!access_request || !layer_masks)
> +		return true;
> +	if (!rule)
> +		return false;
> +
> +	/*
> +	 * An access is granted if, for each policy layer, at least one rule
> +	 * encountered on the pathwalk grants the requested access,
> +	 * regardless of its position in the layer stack.  We must then check
> +	 * the remaining layers for each inode, from the first added layer to
> +	 * the last one.  When there is multiple requested accesses, for each
> +	 * policy layer, the full set of requested accesses may not be granted
> +	 * by only one rule, but by the union (binary OR) of multiple rules.
> +	 * E.g. /a/b <execute> + /a <read> => /a/b <execute + read>
> +	 */
> +	for (layer_level = 0; layer_level < rule->num_layers; layer_level++) {
> +		const struct landlock_layer *const layer =
> +			&rule->layers[layer_level];
> +		const layer_mask_t layer_bit = BIT_ULL(layer->level - 1);
> +		const unsigned long access_req = access_request;
> +		unsigned long access_bit;
> +		bool is_empty;
> +
> +		/*
> +		 * Records in @layer_masks which layer grants access to each
> +		 * requested access.
> +		 */
> +		is_empty = true;
> +		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];
> +		}
> +		if (is_empty)
> +			return true;
> +	}
> +	return false;
> +}
> +
> +access_mask_t init_layer_masks(const struct landlock_ruleset *const domain,
> +			       const access_mask_t access_request,
> +			       layer_mask_t (*const layer_masks)[],
> +			       size_t masks_size,
> +			       u16 rule_type)
> +{
> +	access_mask_t handled_accesses = 0;
> +	size_t layer_level;
> +
> +	memset(layer_masks, 0, masks_size);
> +
> +	/* An empty access request can happen because of O_WRONLY | O_RDWR. */
> +	if (!access_request)
> +		return 0;
> +
> +	/* Saves all handled accesses per layer. */
> +	for (layer_level = 0; layer_level < domain->num_layers;
> +			layer_level++) {
> +		const unsigned long access_req = access_request;
> +		unsigned long access_bit;
> +
> +		switch (rule_type) {
> +		case LANDLOCK_RULE_PATH_BENEATH:
> +			for_each_set_bit(access_bit, &access_req,
> +					LANDLOCK_NUM_ACCESS_FS) {
> +				if (landlock_get_fs_access_mask(domain,
> +								layer_level) &
> +						BIT_ULL(access_bit)) {
> +					(*layer_masks)[access_bit] |=
> +						BIT_ULL(layer_level);
> +					handled_accesses |=
> +							   BIT_ULL(access_bit);
> +				}
> +			}
> +			break;
> +		default:
> +			return 0;
> +		}
> +	}
> +	return handled_accesses;
> +}
> diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h
> index 3066e5d7180c..f3cd890d0348 100644
> --- a/security/landlock/ruleset.h
> +++ b/security/landlock/ruleset.h
> @@ -195,7 +195,22 @@ static inline u32 landlock_get_fs_access_mask(
>   					const struct landlock_ruleset *ruleset,
>   					u16 mask_level)
>   {
> -	return ruleset->access_masks[mask_level];
> +	return (ruleset->access_masks[mask_level] & LANDLOCK_MASK_ACCESS_FS);
>   }
> 
> +access_mask_t get_handled_accesses(
> +		const struct landlock_ruleset *const domain,
> +		u16 rule_type, u16 num_access);
> +
> +bool unmask_layers(const struct landlock_rule *const rule,
> +		   const access_mask_t access_request,
> +		   layer_mask_t (*const layer_masks)[],
> +		   size_t masks_array_size);
> +
> +access_mask_t init_layer_masks(const struct landlock_ruleset *const domain,
> +			       const access_mask_t access_request,
> +			       layer_mask_t (*const layer_masks)[],
> +			       size_t masks_size,
> +			       u16 rule_type);

These declarations are useless.

> +
>   #endif /* _SECURITY_LANDLOCK_RULESET_H */
> --
> 2.25.1
>
Konstantin Meskhidze (A) May 16, 2022, 5:43 p.m. UTC | #2
5/16/2022 8:14 PM, Mickaël Salaün пишет:
> 
> On 16/05/2022 17:20, Konstantin Meskhidze wrote:
>> Unmask_layers(), init_layer_masks() and
>> get_handled_accesses() helper functions move to
>> ruleset.c and rule_type argument is added.
>> This modification supports implementing new rule
>> types into next landlock versions.
>>
>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>
>> ---
>>
>> Changes since v3:
>> * Splits commit.
>> * Refactoring landlock_unmask_layers functions.
>>
> 
> Please sort changes in antichronological order. It is easier to look at 
> the first lines to get the last changes.

  Ok. I will. Thanks
> 
>> Changes since v4:
>> * Refactoring init_layer_masks(), get_handled_accesses()
>> and unmask_layers() functions to support multiple rule types.
>> * Refactoring landlock_get_fs_access_mask() function with
>> LANDLOCK_MASK_ACCESS_FS mask. >
>> ---
>>   security/landlock/fs.c      | 158 ++++++++----------------------------
>>   security/landlock/ruleset.c | 152 +++++++++++++++++++++++++++++++---
>>   security/landlock/ruleset.h |  17 +++-
>>   3 files changed, 192 insertions(+), 135 deletions(-)
>>
>> diff --git a/security/landlock/fs.c b/security/landlock/fs.c
>> index 5de24d4dd74c..3506e182b23e 100644
>> --- a/security/landlock/fs.c
>> +++ b/security/landlock/fs.c
>> @@ -211,60 +211,6 @@ find_rule(const struct landlock_ruleset *const 
>> domain,
>>       return rule;
>>   }
>>
>> -/*
>> - * @layer_masks is read and may be updated according to the access 
>> request and
>> - * the matching rule.
>> - *
>> - * Returns true if the request is allowed (i.e. relevant layer masks 
>> for the
>> - * request are empty).
>> - */
>> -static inline bool
>> -unmask_layers(const struct landlock_rule *const rule,
>> -          const access_mask_t access_request,
>> -          layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS])
> 
> Moving these entire blocks of code make the review/diff impossible. Why 
> moving these helpers?

   Cause these helpers are going to be used both for filesystem and 
network. I moved them into ruleset.c/h
> 
>> -{
>> -    size_t layer_level;
>> -
>> -    if (!access_request || !layer_masks)
>> -        return true;
>> -    if (!rule)
>> -        return false;
>> -
>> -    /*
>> -     * An access is granted if, for each policy layer, at least one rule
>> -     * encountered on the pathwalk grants the requested access,
>> -     * regardless of its position in the layer stack.  We must then 
>> check
>> -     * the remaining layers for each inode, from the first added 
>> layer to
>> -     * the last one.  When there is multiple requested accesses, for 
>> each
>> -     * policy layer, the full set of requested accesses may not be 
>> granted
>> -     * by only one rule, but by the union (binary OR) of multiple rules.
>> -     * E.g. /a/b <execute> + /a <read> => /a/b <execute + read>
>> -     */
>> -    for (layer_level = 0; layer_level < rule->num_layers; 
>> layer_level++) {
>> -        const struct landlock_layer *const layer =
>> -            &rule->layers[layer_level];
>> -        const layer_mask_t layer_bit = BIT_ULL(layer->level - 1);
>> -        const unsigned long access_req = access_request;
>> -        unsigned long access_bit;
>> -        bool is_empty;
>> -
>> -        /*
>> -         * Records in @layer_masks which layer grants access to each
>> -         * requested access.
>> -         */
>> -        is_empty = true;
>> -        for_each_set_bit(access_bit, &access_req,
>> -                 ARRAY_SIZE(*layer_masks)) {
>> -            if (layer->access & BIT_ULL(access_bit))
>> -                (*layer_masks)[access_bit] &= ~layer_bit;
>> -            is_empty = is_empty && !(*layer_masks)[access_bit];
>> -        }
>> -        if (is_empty)
>> -            return true;
>> -    }
>> -    return false;
>> -}
>> -
>>   /*
>>    * Allows access to pseudo filesystems that will never be mountable 
>> (e.g.
>>    * sockfs, pipefs), but can still be reachable through
>> @@ -277,59 +223,6 @@ static inline bool is_nouser_or_private(const 
>> struct dentry *dentry)
>>           unlikely(IS_PRIVATE(d_backing_inode(dentry))));
>>   }
>>
>> -static inline access_mask_t
>> -get_handled_accesses(const struct landlock_ruleset *const domain)
>> -{
>> -    access_mask_t access_dom = 0;
>> -    unsigned long access_bit;
>> -
>> -    for (access_bit = 0; access_bit < LANDLOCK_NUM_ACCESS_FS;
>> -         access_bit++) {
>> -        size_t layer_level;
>> -
>> -        for (layer_level = 0; layer_level < domain->num_layers;
>> -                layer_level++) {
>> -            if (landlock_get_fs_access_mask(domain, layer_level) &
>> -                    BIT_ULL(access_bit)) {
>> -                access_dom |= BIT_ULL(access_bit);
>> -                break;
>> -            }
>> -        }
>> -    }
>> -    return access_dom;
>> -}
>> -
>> -static inline access_mask_t
>> -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])
>> -{
>> -    access_mask_t handled_accesses = 0;
>> -    size_t layer_level;
>> -
>> -    memset(layer_masks, 0, sizeof(*layer_masks));
>> -    /* An empty access request can happen because of O_WRONLY | 
>> O_RDWR. */
>> -    if (!access_request)
>> -        return 0;
>> -
>> -    /* Saves all handled accesses per layer. */
>> -    for (layer_level = 0; layer_level < domain->num_layers; 
>> layer_level++) {
>> -        const unsigned long access_req = access_request;
>> -        unsigned long access_bit;
>> -
>> -        for_each_set_bit(access_bit, &access_req,
>> -                ARRAY_SIZE(*layer_masks)) {
>> -            if (landlock_get_fs_access_mask(domain, layer_level) &
>> -                    BIT_ULL(access_bit)) {
>> -                (*layer_masks)[access_bit] |=
>> -                    BIT_ULL(layer_level);
>> -                handled_accesses |= BIT_ULL(access_bit);
>> -            }
>> -        }
>> -    }
>> -    return handled_accesses;
>> -}
>> -
>>   /*
>>    * Check that a destination file hierarchy has more restrictions 
>> than a source
>>    * file hierarchy.  This is only used for link and rename actions.
>> @@ -506,7 +399,8 @@ static int check_access_path_dual(
>>            * a superset of the meaningful requested accesses).
>>            */
>>           access_masked_parent1 = access_masked_parent2 =
>> -            get_handled_accesses(domain);
>> +            get_handled_accesses(domain, LANDLOCK_RULE_PATH_BENEATH,
>> +                         LANDLOCK_NUM_ACCESS_FS);
>>           is_dom_check = true;
>>       } else {
>>           if (WARN_ON_ONCE(dentry_child1 || dentry_child2))
>> @@ -519,17 +413,25 @@ static int check_access_path_dual(
>>
>>       if (unlikely(dentry_child1)) {
>>           unmask_layers(find_rule(domain, dentry_child1),
>> -                  init_layer_masks(domain, LANDLOCK_MASK_ACCESS_FS,
>> -                           &_layer_masks_child1),
>> -                  &_layer_masks_child1);
>> +                init_layer_masks(domain,
>> +                    LANDLOCK_MASK_ACCESS_FS,
>> +                    &_layer_masks_child1,
>> +                    sizeof(_layer_masks_child1),
>> +                    LANDLOCK_RULE_PATH_BENEATH),
>> +                &_layer_masks_child1,
>> +                ARRAY_SIZE(_layer_masks_child1));
> 
> There is a lot of formatting diff and that makes the review difficult. 
> Please format everything with clang-format-14.

   Ok. Do you have some tool that helps you with editing code with clang 
format?
> 
>>           layer_masks_child1 = &_layer_masks_child1;
>>           child1_is_directory = d_is_dir(dentry_child1);
>>       }
>>       if (unlikely(dentry_child2)) {
>>           unmask_layers(find_rule(domain, dentry_child2),
>> -                  init_layer_masks(domain, LANDLOCK_MASK_ACCESS_FS,
>> -                           &_layer_masks_child2),
>> -                  &_layer_masks_child2);
>> +                init_layer_masks(domain,
>> +                    LANDLOCK_MASK_ACCESS_FS,
>> +                    &_layer_masks_child2,
>> +                    sizeof(_layer_masks_child2),
>> +                    LANDLOCK_RULE_PATH_BENEATH),
>> +                &_layer_masks_child2,
>> +                ARRAY_SIZE(_layer_masks_child2));
>>           layer_masks_child2 = &_layer_masks_child2;
>>           child2_is_directory = d_is_dir(dentry_child2);
>>       }
>> @@ -582,14 +484,15 @@ static int check_access_path_dual(
>>
>>           rule = find_rule(domain, walker_path.dentry);
>>           allowed_parent1 = unmask_layers(rule, access_masked_parent1,
>> -                        layer_masks_parent1);
>> +                layer_masks_parent1,
>> +                ARRAY_SIZE(*layer_masks_parent1));
>>           allowed_parent2 = unmask_layers(rule, access_masked_parent2,
>> -                        layer_masks_parent2);
>> +                layer_masks_parent2,
>> +                ARRAY_SIZE(*layer_masks_parent2));
>>
>>           /* Stops when a rule from each layer grants access. */
>>           if (allowed_parent1 && allowed_parent2)
>>               break;
>> -
> 
> There is no place for such formatting/whitespace patches.
> 
   I missed that. scripts/checkpatch.pl did not show any problem here.
   I will fix it. Thanks.
> 
>>   jump_up:
>>           if (walker_path.dentry == walker_path.mnt->mnt_root) {
>>               if (follow_up(&walker_path)) {
>> @@ -645,7 +548,9 @@ static inline int check_access_path(const struct 
>> landlock_ruleset *const domain,
>>   {
>>       layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_FS] = {};
>>
>> -    access_request = init_layer_masks(domain, access_request, 
>> &layer_masks);
>> +    access_request = init_layer_masks(domain, access_request,
>> +            &layer_masks, sizeof(layer_masks),
>> +            LANDLOCK_RULE_PATH_BENEATH);
>>       return check_access_path_dual(domain, path, access_request,
>>                         &layer_masks, NULL, 0, NULL, NULL);
>>   }
>> @@ -729,7 +634,8 @@ static bool collect_domain_accesses(
>>           return true;
>>
>>       access_dom = init_layer_masks(domain, LANDLOCK_MASK_ACCESS_FS,
>> -                      layer_masks_dom);
>> +            layer_masks_dom, sizeof(*layer_masks_dom),
>> +            LANDLOCK_RULE_PATH_BENEATH);
>>
>>       dget(dir);
>>       while (true) {
>> @@ -737,7 +643,8 @@ static bool collect_domain_accesses(
>>
>>           /* Gets all layers allowing all domain accesses. */
>>           if (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.
>> @@ -851,9 +758,10 @@ static int current_check_refer_path(struct dentry 
>> *const old_dentry,
>>            * The LANDLOCK_ACCESS_FS_REFER access right is not required
>>            * for same-directory referer (i.e. no reparenting).
>>            */
>> -        access_request_parent1 = init_layer_masks(
>> -            dom, access_request_parent1 | access_request_parent2,
>> -            &layer_masks_parent1);
>> +        access_request_parent1 = init_layer_masks(dom,
>> +                access_request_parent1 | access_request_parent2,
>> +                &layer_masks_parent1, sizeof(layer_masks_parent1),
>> +                LANDLOCK_RULE_PATH_BENEATH);
>>           return check_access_path_dual(dom, new_dir,
>>                             access_request_parent1,
>>                             &layer_masks_parent1, NULL, 0,
>> @@ -861,7 +769,9 @@ static int current_check_refer_path(struct dentry 
>> *const old_dentry,
>>       }
>>
>>       /* Backward compatibility: no reparenting support. */
>> -    if (!(get_handled_accesses(dom) & LANDLOCK_ACCESS_FS_REFER))
>> +    if (!(get_handled_accesses(dom, LANDLOCK_RULE_PATH_BENEATH,
>> +                   LANDLOCK_NUM_ACCESS_FS) &
>> +                        LANDLOCK_ACCESS_FS_REFER))
>>           return -EXDEV;
>>
>>       access_request_parent1 |= LANDLOCK_ACCESS_FS_REFER;
>> diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
>> index 4b4c9953bb32..c4ed783d655b 100644
>> --- a/security/landlock/ruleset.c
>> +++ b/security/landlock/ruleset.c
>> @@ -233,7 +233,8 @@ static int insert_rule(struct landlock_ruleset 
>> *const ruleset,
>>                              &(*layers)[0]);
>>               if (IS_ERR(new_rule))
>>                   return PTR_ERR(new_rule);
>> -            rb_replace_node(&this->node, &new_rule->node, 
>> &ruleset->root_inode);
>> +            rb_replace_node(&this->node, &new_rule->node,
>> +                    &ruleset->root_inode);
> 
> This is a pure formatting hunk. :/
> 
   Thats strange, cause in my editor I have normal aligment of arguments.
   Could please share clang-format-14 tab size and other format 	parameters?
> 
>>               free_rule(this, rule_type);
>>               break;
>>           }
>> @@ -246,7 +247,8 @@ static int insert_rule(struct landlock_ruleset 
>> *const ruleset,
>>           return -E2BIG;
>>       switch (rule_type) {
>>       case LANDLOCK_RULE_PATH_BENEATH:
>> -        new_rule = create_rule(object_ptr, 0, layers, num_layers, NULL);
>> +        new_rule = create_rule(object_ptr, 0, layers,
>> +                       num_layers, NULL);
>>           if (IS_ERR(new_rule))
>>               return PTR_ERR(new_rule);
>>           rb_link_node(&new_rule->node, parent_node, walker_node);
>> @@ -281,8 +283,8 @@ int landlock_insert_rule(struct landlock_ruleset 
>> *const ruleset,
>>       } };
>>
>>       build_check_layer();
>> -    return insert_rule(ruleset, object_ptr, object_data, rule_type, 
>> &layers,
>> -               ARRAY_SIZE(layers));
>> +    return insert_rule(ruleset, object_ptr, object_data, rule_type,
>> +               &layers, ARRAY_SIZE(layers));
>>   }
>>
>>   static inline void get_hierarchy(struct landlock_hierarchy *const 
>> hierarchy)
>> @@ -335,8 +337,9 @@ static int tree_merge(struct landlock_ruleset 
>> *const src,
>>
>>           switch (rule_type) {
>>           case LANDLOCK_RULE_PATH_BENEATH:
>> -            err = insert_rule(dst, walker_rule->object.ptr, 0, 
>> rule_type,
>> -                      &layers, ARRAY_SIZE(layers));
>> +            err = insert_rule(dst, walker_rule->object.ptr, 0,
>> +                      rule_type, &layers,
>> +                      ARRAY_SIZE(layers));
>>               break;
>>           }
>>           if (err)
>> @@ -433,9 +436,13 @@ static int inherit_ruleset(struct 
>> landlock_ruleset *const parent,
>>           err = -EINVAL;
>>           goto out_unlock;
>>       }
>> -    /* Copies the parent layer stack and leaves a space for the new 
>> layer. */
>> +    /*
>> +     * Copies the parent layer stack and leaves a space
>> +     * for the new layer.
>> +     */
>>       memcpy(child->access_masks, parent->access_masks,
>> -            flex_array_size(parent, access_masks, parent->num_layers));
>> +            flex_array_size(parent, access_masks,
>> +                    parent->num_layers));
>>
>>       if (WARN_ON_ONCE(!parent->hierarchy)) {
>>           err = -EINVAL;
>> @@ -455,8 +462,9 @@ static void free_ruleset(struct landlock_ruleset 
>> *const ruleset)
>>       struct landlock_rule *freeme, *next;
>>
>>       might_sleep();
>> -    rbtree_postorder_for_each_entry_safe(freeme, next, 
>> &ruleset->root_inode,
>> -            node)
>> +    rbtree_postorder_for_each_entry_safe(freeme, next,
>> +                         &ruleset->root_inode,
>> +                         node)
>>           free_rule(freeme, LANDLOCK_RULE_PATH_BENEATH);
>>       put_hierarchy(ruleset->hierarchy);
>>       kfree(ruleset);
>> @@ -577,3 +585,127 @@ const struct landlock_rule *landlock_find_rule(
>>       }
>>       return NULL;
>>   }
>> +
>> +access_mask_t get_handled_accesses(
>> +        const struct landlock_ruleset *const domain,
>> +        u16 rule_type, u16 num_access)
>> +{
>> +    access_mask_t access_dom = 0;
>> +    unsigned long access_bit;
>> +
>> +    switch (rule_type) {
>> +    case LANDLOCK_RULE_PATH_BENEATH:
>> +        for (access_bit = 0; access_bit < LANDLOCK_NUM_ACCESS_FS;
>> +            access_bit++) {
>> +            size_t layer_level;
>> +
>> +            for (layer_level = 0; layer_level < domain->num_layers;
>> +                    layer_level++) {
>> +                if (landlock_get_fs_access_mask(domain,
>> +                                layer_level) &
>> +                        BIT_ULL(access_bit)) {
>> +                    access_dom |= BIT_ULL(access_bit);
>> +                    break;
>> +                }
>> +            }
>> +        }
>> +        break;
>> +    default:
>> +        break;
>> +    }
>> +    return access_dom;
>> +}
>> +
>> +/*
>> + * @layer_masks is read and may be updated according to the access 
>> request and
>> + * the matching rule.
>> + *
>> + * Returns true if the request is allowed (i.e. relevant layer masks 
>> for the
>> + * request are empty).
>> + */
>> +bool unmask_layers(const struct landlock_rule *const rule,
>> +        const access_mask_t access_request,
>> +        layer_mask_t (*const layer_masks)[], size_t masks_array_size)
>> +{
>> +    size_t layer_level;
>> +
>> +    if (!access_request || !layer_masks)
>> +        return true;
>> +    if (!rule)
>> +        return false;
>> +
>> +    /*
>> +     * An access is granted if, for each policy layer, at least one rule
>> +     * encountered on the pathwalk grants the requested access,
>> +     * regardless of its position in the layer stack.  We must then 
>> check
>> +     * the remaining layers for each inode, from the first added 
>> layer to
>> +     * the last one.  When there is multiple requested accesses, for 
>> each
>> +     * policy layer, the full set of requested accesses may not be 
>> granted
>> +     * by only one rule, but by the union (binary OR) of multiple rules.
>> +     * E.g. /a/b <execute> + /a <read> => /a/b <execute + read>
>> +     */
>> +    for (layer_level = 0; layer_level < rule->num_layers; 
>> layer_level++) {
>> +        const struct landlock_layer *const layer =
>> +            &rule->layers[layer_level];
>> +        const layer_mask_t layer_bit = BIT_ULL(layer->level - 1);
>> +        const unsigned long access_req = access_request;
>> +        unsigned long access_bit;
>> +        bool is_empty;
>> +
>> +        /*
>> +         * Records in @layer_masks which layer grants access to each
>> +         * requested access.
>> +         */
>> +        is_empty = true;
>> +        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];
>> +        }
>> +        if (is_empty)
>> +            return true;
>> +    }
>> +    return false;
>> +}
>> +
>> +access_mask_t init_layer_masks(const struct landlock_ruleset *const 
>> domain,
>> +                   const access_mask_t access_request,
>> +                   layer_mask_t (*const layer_masks)[],
>> +                   size_t masks_size,
>> +                   u16 rule_type)
>> +{
>> +    access_mask_t handled_accesses = 0;
>> +    size_t layer_level;
>> +
>> +    memset(layer_masks, 0, masks_size);
>> +
>> +    /* An empty access request can happen because of O_WRONLY | 
>> O_RDWR. */
>> +    if (!access_request)
>> +        return 0;
>> +
>> +    /* Saves all handled accesses per layer. */
>> +    for (layer_level = 0; layer_level < domain->num_layers;
>> +            layer_level++) {
>> +        const unsigned long access_req = access_request;
>> +        unsigned long access_bit;
>> +
>> +        switch (rule_type) {
>> +        case LANDLOCK_RULE_PATH_BENEATH:
>> +            for_each_set_bit(access_bit, &access_req,
>> +                    LANDLOCK_NUM_ACCESS_FS) {
>> +                if (landlock_get_fs_access_mask(domain,
>> +                                layer_level) &
>> +                        BIT_ULL(access_bit)) {
>> +                    (*layer_masks)[access_bit] |=
>> +                        BIT_ULL(layer_level);
>> +                    handled_accesses |=
>> +                               BIT_ULL(access_bit);
>> +                }
>> +            }
>> +            break;
>> +        default:
>> +            return 0;
>> +        }
>> +    }
>> +    return handled_accesses;
>> +}
>> diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h
>> index 3066e5d7180c..f3cd890d0348 100644
>> --- a/security/landlock/ruleset.h
>> +++ b/security/landlock/ruleset.h
>> @@ -195,7 +195,22 @@ static inline u32 landlock_get_fs_access_mask(
>>                       const struct landlock_ruleset *ruleset,
>>                       u16 mask_level)
>>   {
>> -    return ruleset->access_masks[mask_level];
>> +    return (ruleset->access_masks[mask_level] & 
>> LANDLOCK_MASK_ACCESS_FS);
>>   }
>>
>> +access_mask_t get_handled_accesses(
>> +        const struct landlock_ruleset *const domain,
>> +        u16 rule_type, u16 num_access);
>> +
>> +bool unmask_layers(const struct landlock_rule *const rule,
>> +           const access_mask_t access_request,
>> +           layer_mask_t (*const layer_masks)[],
>> +           size_t masks_array_size);
>> +
>> +access_mask_t init_layer_masks(const struct landlock_ruleset *const 
>> domain,
>> +                   const access_mask_t access_request,
>> +                   layer_mask_t (*const layer_masks)[],
>> +                   size_t masks_size,
>> +                   u16 rule_type);
> 
> These declarations are useless.

   I moved helpers in rulset.c/h to use them both for filesystem
and network.
> 
>> +
>>   #endif /* _SECURITY_LANDLOCK_RULESET_H */
>> -- 
>> 2.25.1
>>
> .
Mickaël Salaün May 16, 2022, 6:28 p.m. UTC | #3
On 16/05/2022 19:43, Konstantin Meskhidze wrote:
> 
> 
> 5/16/2022 8:14 PM, Mickaël Salaün пишет:
>>
>> On 16/05/2022 17:20, Konstantin Meskhidze wrote:
>>> Unmask_layers(), init_layer_masks() and
>>> get_handled_accesses() helper functions move to
>>> ruleset.c and rule_type argument is added.
>>> This modification supports implementing new rule
>>> types into next landlock versions.
>>>
>>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>

[...]

>>> -/*
>>> - * @layer_masks is read and may be updated according to the access 
>>> request and
>>> - * the matching rule.
>>> - *
>>> - * Returns true if the request is allowed (i.e. relevant layer masks 
>>> for the
>>> - * request are empty).
>>> - */
>>> -static inline bool
>>> -unmask_layers(const struct landlock_rule *const rule,
>>> -          const access_mask_t access_request,
>>> -          layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS])
>>
>> Moving these entire blocks of code make the review/diff impossible. 
>> Why moving these helpers?
> 
>    Cause these helpers are going to be used both for filesystem and 
> network. I moved them into ruleset.c/h

Right. Please create a commit which only moves these helpers without 
modifying them, and explain in the commit message that this removes 
inlined code. We'll see later if this adds a visible performance impact.

[...]

>>> @@ -519,17 +413,25 @@ static int check_access_path_dual(
>>>
>>>       if (unlikely(dentry_child1)) {
>>>           unmask_layers(find_rule(domain, dentry_child1),
>>> -                  init_layer_masks(domain, LANDLOCK_MASK_ACCESS_FS,
>>> -                           &_layer_masks_child1),
>>> -                  &_layer_masks_child1);
>>> +                init_layer_masks(domain,
>>> +                    LANDLOCK_MASK_ACCESS_FS,
>>> +                    &_layer_masks_child1,
>>> +                    sizeof(_layer_masks_child1),
>>> +                    LANDLOCK_RULE_PATH_BENEATH),
>>> +                &_layer_masks_child1,
>>> +                ARRAY_SIZE(_layer_masks_child1));
>>
>> There is a lot of formatting diff and that makes the review difficult. 
>> Please format everything with clang-format-14.
> 
>    Ok. Do you have some tool that helps you with editing code with clang 
> format?

I just run `clang-format-14 -i` on files before each commit. Some 
editors such as VSCode can handle the clang-format configuration (which 
is in the Linux source tree).


>>
>>>           layer_masks_child1 = &_layer_masks_child1;
>>>           child1_is_directory = d_is_dir(dentry_child1);
>>>       }
>>>       if (unlikely(dentry_child2)) {
>>>           unmask_layers(find_rule(domain, dentry_child2),
>>> -                  init_layer_masks(domain, LANDLOCK_MASK_ACCESS_FS,
>>> -                           &_layer_masks_child2),
>>> -                  &_layer_masks_child2);
>>> +                init_layer_masks(domain,
>>> +                    LANDLOCK_MASK_ACCESS_FS,
>>> +                    &_layer_masks_child2,
>>> +                    sizeof(_layer_masks_child2),
>>> +                    LANDLOCK_RULE_PATH_BENEATH),
>>> +                &_layer_masks_child2,
>>> +                ARRAY_SIZE(_layer_masks_child2));
>>>           layer_masks_child2 = &_layer_masks_child2;
>>>           child2_is_directory = d_is_dir(dentry_child2);
>>>       }
>>> @@ -582,14 +484,15 @@ static int check_access_path_dual(
>>>
>>>           rule = find_rule(domain, walker_path.dentry);
>>>           allowed_parent1 = unmask_layers(rule, access_masked_parent1,
>>> -                        layer_masks_parent1);
>>> +                layer_masks_parent1,
>>> +                ARRAY_SIZE(*layer_masks_parent1));
>>>           allowed_parent2 = unmask_layers(rule, access_masked_parent2,
>>> -                        layer_masks_parent2);
>>> +                layer_masks_parent2,
>>> +                ARRAY_SIZE(*layer_masks_parent2));
>>>
>>>           /* Stops when a rule from each layer grants access. */
>>>           if (allowed_parent1 && allowed_parent2)
>>>               break;
>>> -
>>
>> There is no place for such formatting/whitespace patches.
>>
>    I missed that. scripts/checkpatch.pl did not show any problem here.

checkpatch.pl doesn't warn about whitespace changes.


>    I will fix it. Thanks.
>>
>>>   jump_up:
>>>           if (walker_path.dentry == walker_path.mnt->mnt_root) {
>>>               if (follow_up(&walker_path)) {
>>> @@ -645,7 +548,9 @@ static inline int check_access_path(const struct 
>>> landlock_ruleset *const domain,
>>>   {
>>>       layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_FS] = {};
>>>
>>> -    access_request = init_layer_masks(domain, access_request, 
>>> &layer_masks);
>>> +    access_request = init_layer_masks(domain, access_request,
>>> +            &layer_masks, sizeof(layer_masks),
>>> +            LANDLOCK_RULE_PATH_BENEATH);
>>>       return check_access_path_dual(domain, path, access_request,
>>>                         &layer_masks, NULL, 0, NULL, NULL);
>>>   }
>>> @@ -729,7 +634,8 @@ static bool collect_domain_accesses(
>>>           return true;
>>>
>>>       access_dom = init_layer_masks(domain, LANDLOCK_MASK_ACCESS_FS,
>>> -                      layer_masks_dom);
>>> +            layer_masks_dom, sizeof(*layer_masks_dom),
>>> +            LANDLOCK_RULE_PATH_BENEATH);
>>>
>>>       dget(dir);
>>>       while (true) {
>>> @@ -737,7 +643,8 @@ static bool collect_domain_accesses(
>>>
>>>           /* Gets all layers allowing all domain accesses. */
>>>           if (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.
>>> @@ -851,9 +758,10 @@ static int current_check_refer_path(struct 
>>> dentry *const old_dentry,
>>>            * The LANDLOCK_ACCESS_FS_REFER access right is not required
>>>            * for same-directory referer (i.e. no reparenting).
>>>            */
>>> -        access_request_parent1 = init_layer_masks(
>>> -            dom, access_request_parent1 | access_request_parent2,
>>> -            &layer_masks_parent1);
>>> +        access_request_parent1 = init_layer_masks(dom,
>>> +                access_request_parent1 | access_request_parent2,
>>> +                &layer_masks_parent1, sizeof(layer_masks_parent1),
>>> +                LANDLOCK_RULE_PATH_BENEATH);
>>>           return check_access_path_dual(dom, new_dir,
>>>                             access_request_parent1,
>>>                             &layer_masks_parent1, NULL, 0,
>>> @@ -861,7 +769,9 @@ static int current_check_refer_path(struct dentry 
>>> *const old_dentry,
>>>       }
>>>
>>>       /* Backward compatibility: no reparenting support. */
>>> -    if (!(get_handled_accesses(dom) & LANDLOCK_ACCESS_FS_REFER))
>>> +    if (!(get_handled_accesses(dom, LANDLOCK_RULE_PATH_BENEATH,
>>> +                   LANDLOCK_NUM_ACCESS_FS) &
>>> +                        LANDLOCK_ACCESS_FS_REFER))
>>>           return -EXDEV;
>>>
>>>       access_request_parent1 |= LANDLOCK_ACCESS_FS_REFER;
>>> diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
>>> index 4b4c9953bb32..c4ed783d655b 100644
>>> --- a/security/landlock/ruleset.c
>>> +++ b/security/landlock/ruleset.c
>>> @@ -233,7 +233,8 @@ static int insert_rule(struct landlock_ruleset 
>>> *const ruleset,
>>>                              &(*layers)[0]);
>>>               if (IS_ERR(new_rule))
>>>                   return PTR_ERR(new_rule);
>>> -            rb_replace_node(&this->node, &new_rule->node, 
>>> &ruleset->root_inode);
>>> +            rb_replace_node(&this->node, &new_rule->node,
>>> +                    &ruleset->root_inode);
>>
>> This is a pure formatting hunk. :/
>>
>    Thats strange, cause in my editor I have normal aligment of arguments.
>    Could please share clang-format-14 tab size and other format     
> parameters?

They are in the .clang-format file. It would be much easier to just run 
clang-format-14 -i on your changed files. I guess you had different 
changes between consecutive commits.
Konstantin Meskhidze (A) May 18, 2022, 9:14 a.m. UTC | #4
5/16/2022 9:28 PM, Mickaël Salaün пишет:
> 
> On 16/05/2022 19:43, Konstantin Meskhidze wrote:
>>
>>
>> 5/16/2022 8:14 PM, Mickaël Salaün пишет:
>>>
>>> On 16/05/2022 17:20, Konstantin Meskhidze wrote:
>>>> Unmask_layers(), init_layer_masks() and
>>>> get_handled_accesses() helper functions move to
>>>> ruleset.c and rule_type argument is added.
>>>> This modification supports implementing new rule
>>>> types into next landlock versions.
>>>>
>>>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>
> 
> [...]
> 
>>>> -/*
>>>> - * @layer_masks is read and may be updated according to the access 
>>>> request and
>>>> - * the matching rule.
>>>> - *
>>>> - * Returns true if the request is allowed (i.e. relevant layer 
>>>> masks for the
>>>> - * request are empty).
>>>> - */
>>>> -static inline bool
>>>> -unmask_layers(const struct landlock_rule *const rule,
>>>> -          const access_mask_t access_request,
>>>> -          layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS])
>>>
>>> Moving these entire blocks of code make the review/diff impossible. 
>>> Why moving these helpers?
>>
>>    Cause these helpers are going to be used both for filesystem and 
>> network. I moved them into ruleset.c/h
> 
> Right. Please create a commit which only moves these helpers without 
> modifying them, and explain in the commit message that this removes 
> inlined code. We'll see later if this adds a visible performance impact.
> 
    Ok. I will create towo commits - the first one moves helpers to 
ruleset.c/h and the second one changes helpers to support network.
> [...]
> 
>>>> @@ -519,17 +413,25 @@ static int check_access_path_dual(
>>>>
>>>>       if (unlikely(dentry_child1)) {
>>>>           unmask_layers(find_rule(domain, dentry_child1),
>>>> -                  init_layer_masks(domain, LANDLOCK_MASK_ACCESS_FS,
>>>> -                           &_layer_masks_child1),
>>>> -                  &_layer_masks_child1);
>>>> +                init_layer_masks(domain,
>>>> +                    LANDLOCK_MASK_ACCESS_FS,
>>>> +                    &_layer_masks_child1,
>>>> +                    sizeof(_layer_masks_child1),
>>>> +                    LANDLOCK_RULE_PATH_BENEATH),
>>>> +                &_layer_masks_child1,
>>>> +                ARRAY_SIZE(_layer_masks_child1));
>>>
>>> There is a lot of formatting diff and that makes the review 
>>> difficult. Please format everything with clang-format-14.
>>
>>    Ok. Do you have some tool that helps you with editing code with 
>> clang format?
> 
> I just run `clang-format-14 -i` on files before each commit. Some 
> editors such as VSCode can handle the clang-format configuration (which 
> is in the Linux source tree).
> 
  Ok. I have updated installed cloang-format-14 executable and setup my 
VSCode to use .clang-format file.
> 
>>>
>>>>           layer_masks_child1 = &_layer_masks_child1;
>>>>           child1_is_directory = d_is_dir(dentry_child1);
>>>>       }
>>>>       if (unlikely(dentry_child2)) {
>>>>           unmask_layers(find_rule(domain, dentry_child2),
>>>> -                  init_layer_masks(domain, LANDLOCK_MASK_ACCESS_FS,
>>>> -                           &_layer_masks_child2),
>>>> -                  &_layer_masks_child2);
>>>> +                init_layer_masks(domain,
>>>> +                    LANDLOCK_MASK_ACCESS_FS,
>>>> +                    &_layer_masks_child2,
>>>> +                    sizeof(_layer_masks_child2),
>>>> +                    LANDLOCK_RULE_PATH_BENEATH),
>>>> +                &_layer_masks_child2,
>>>> +                ARRAY_SIZE(_layer_masks_child2));
>>>>           layer_masks_child2 = &_layer_masks_child2;
>>>>           child2_is_directory = d_is_dir(dentry_child2);
>>>>       }
>>>> @@ -582,14 +484,15 @@ static int check_access_path_dual(
>>>>
>>>>           rule = find_rule(domain, walker_path.dentry);
>>>>           allowed_parent1 = unmask_layers(rule, access_masked_parent1,
>>>> -                        layer_masks_parent1);
>>>> +                layer_masks_parent1,
>>>> +                ARRAY_SIZE(*layer_masks_parent1));
>>>>           allowed_parent2 = unmask_layers(rule, access_masked_parent2,
>>>> -                        layer_masks_parent2);
>>>> +                layer_masks_parent2,
>>>> +                ARRAY_SIZE(*layer_masks_parent2));
>>>>
>>>>           /* Stops when a rule from each layer grants access. */
>>>>           if (allowed_parent1 && allowed_parent2)
>>>>               break;
>>>> -
>>>
>>> There is no place for such formatting/whitespace patches.
>>>
>>    I missed that. scripts/checkpatch.pl did not show any problem here.
> 
> checkpatch.pl doesn't warn about whitespace changes.

   yep. I will use Vscode clang plugin to follow the required code style.
> 
> 
>>    I will fix it. Thanks.
>>>
>>>>   jump_up:
>>>>           if (walker_path.dentry == walker_path.mnt->mnt_root) {
>>>>               if (follow_up(&walker_path)) {
>>>> @@ -645,7 +548,9 @@ static inline int check_access_path(const struct 
>>>> landlock_ruleset *const domain,
>>>>   {
>>>>       layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_FS] = {};
>>>>
>>>> -    access_request = init_layer_masks(domain, access_request, 
>>>> &layer_masks);
>>>> +    access_request = init_layer_masks(domain, access_request,
>>>> +            &layer_masks, sizeof(layer_masks),
>>>> +            LANDLOCK_RULE_PATH_BENEATH);
>>>>       return check_access_path_dual(domain, path, access_request,
>>>>                         &layer_masks, NULL, 0, NULL, NULL);
>>>>   }
>>>> @@ -729,7 +634,8 @@ static bool collect_domain_accesses(
>>>>           return true;
>>>>
>>>>       access_dom = init_layer_masks(domain, LANDLOCK_MASK_ACCESS_FS,
>>>> -                      layer_masks_dom);
>>>> +            layer_masks_dom, sizeof(*layer_masks_dom),
>>>> +            LANDLOCK_RULE_PATH_BENEATH);
>>>>
>>>>       dget(dir);
>>>>       while (true) {
>>>> @@ -737,7 +643,8 @@ static bool collect_domain_accesses(
>>>>
>>>>           /* Gets all layers allowing all domain accesses. */
>>>>           if (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.
>>>> @@ -851,9 +758,10 @@ static int current_check_refer_path(struct 
>>>> dentry *const old_dentry,
>>>>            * The LANDLOCK_ACCESS_FS_REFER access right is not required
>>>>            * for same-directory referer (i.e. no reparenting).
>>>>            */
>>>> -        access_request_parent1 = init_layer_masks(
>>>> -            dom, access_request_parent1 | access_request_parent2,
>>>> -            &layer_masks_parent1);
>>>> +        access_request_parent1 = init_layer_masks(dom,
>>>> +                access_request_parent1 | access_request_parent2,
>>>> +                &layer_masks_parent1, sizeof(layer_masks_parent1),
>>>> +                LANDLOCK_RULE_PATH_BENEATH);
>>>>           return check_access_path_dual(dom, new_dir,
>>>>                             access_request_parent1,
>>>>                             &layer_masks_parent1, NULL, 0,
>>>> @@ -861,7 +769,9 @@ static int current_check_refer_path(struct 
>>>> dentry *const old_dentry,
>>>>       }
>>>>
>>>>       /* Backward compatibility: no reparenting support. */
>>>> -    if (!(get_handled_accesses(dom) & LANDLOCK_ACCESS_FS_REFER))
>>>> +    if (!(get_handled_accesses(dom, LANDLOCK_RULE_PATH_BENEATH,
>>>> +                   LANDLOCK_NUM_ACCESS_FS) &
>>>> +                        LANDLOCK_ACCESS_FS_REFER))
>>>>           return -EXDEV;
>>>>
>>>>       access_request_parent1 |= LANDLOCK_ACCESS_FS_REFER;
>>>> diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
>>>> index 4b4c9953bb32..c4ed783d655b 100644
>>>> --- a/security/landlock/ruleset.c
>>>> +++ b/security/landlock/ruleset.c
>>>> @@ -233,7 +233,8 @@ static int insert_rule(struct landlock_ruleset 
>>>> *const ruleset,
>>>>                              &(*layers)[0]);
>>>>               if (IS_ERR(new_rule))
>>>>                   return PTR_ERR(new_rule);
>>>> -            rb_replace_node(&this->node, &new_rule->node, 
>>>> &ruleset->root_inode);
>>>> +            rb_replace_node(&this->node, &new_rule->node,
>>>> +                    &ruleset->root_inode);
>>>
>>> This is a pure formatting hunk. :/
>>>
>>    Thats strange, cause in my editor I have normal aligment of arguments.
>>    Could please share clang-format-14 tab size and other format 
>> parameters?
> 
> They are in the .clang-format file. It would be much easier to just run 
> clang-format-14 -i on your changed files. I guess you had different 
> changes between consecutive commits.

  Yep. Thnank you for help here.
> .
diff mbox series

Patch

diff --git a/security/landlock/fs.c b/security/landlock/fs.c
index 5de24d4dd74c..3506e182b23e 100644
--- a/security/landlock/fs.c
+++ b/security/landlock/fs.c
@@ -211,60 +211,6 @@  find_rule(const struct landlock_ruleset *const domain,
 	return rule;
 }

-/*
- * @layer_masks is read and may be updated according to the access request and
- * the matching rule.
- *
- * Returns true if the request is allowed (i.e. relevant layer masks for the
- * request are empty).
- */
-static inline bool
-unmask_layers(const struct landlock_rule *const rule,
-	      const access_mask_t access_request,
-	      layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS])
-{
-	size_t layer_level;
-
-	if (!access_request || !layer_masks)
-		return true;
-	if (!rule)
-		return false;
-
-	/*
-	 * An access is granted if, for each policy layer, at least one rule
-	 * encountered on the pathwalk grants the requested access,
-	 * regardless of its position in the layer stack.  We must then check
-	 * the remaining layers for each inode, from the first added layer to
-	 * the last one.  When there is multiple requested accesses, for each
-	 * policy layer, the full set of requested accesses may not be granted
-	 * by only one rule, but by the union (binary OR) of multiple rules.
-	 * E.g. /a/b <execute> + /a <read> => /a/b <execute + read>
-	 */
-	for (layer_level = 0; layer_level < rule->num_layers; layer_level++) {
-		const struct landlock_layer *const layer =
-			&rule->layers[layer_level];
-		const layer_mask_t layer_bit = BIT_ULL(layer->level - 1);
-		const unsigned long access_req = access_request;
-		unsigned long access_bit;
-		bool is_empty;
-
-		/*
-		 * Records in @layer_masks which layer grants access to each
-		 * requested access.
-		 */
-		is_empty = true;
-		for_each_set_bit(access_bit, &access_req,
-				 ARRAY_SIZE(*layer_masks)) {
-			if (layer->access & BIT_ULL(access_bit))
-				(*layer_masks)[access_bit] &= ~layer_bit;
-			is_empty = is_empty && !(*layer_masks)[access_bit];
-		}
-		if (is_empty)
-			return true;
-	}
-	return false;
-}
-
 /*
  * Allows access to pseudo filesystems that will never be mountable (e.g.
  * sockfs, pipefs), but can still be reachable through
@@ -277,59 +223,6 @@  static inline bool is_nouser_or_private(const struct dentry *dentry)
 		unlikely(IS_PRIVATE(d_backing_inode(dentry))));
 }

-static inline access_mask_t
-get_handled_accesses(const struct landlock_ruleset *const domain)
-{
-	access_mask_t access_dom = 0;
-	unsigned long access_bit;
-
-	for (access_bit = 0; access_bit < LANDLOCK_NUM_ACCESS_FS;
-	     access_bit++) {
-		size_t layer_level;
-
-		for (layer_level = 0; layer_level < domain->num_layers;
-				layer_level++) {
-			if (landlock_get_fs_access_mask(domain, layer_level) &
-					BIT_ULL(access_bit)) {
-				access_dom |= BIT_ULL(access_bit);
-				break;
-			}
-		}
-	}
-	return access_dom;
-}
-
-static inline access_mask_t
-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])
-{
-	access_mask_t handled_accesses = 0;
-	size_t layer_level;
-
-	memset(layer_masks, 0, sizeof(*layer_masks));
-	/* An empty access request can happen because of O_WRONLY | O_RDWR. */
-	if (!access_request)
-		return 0;
-
-	/* Saves all handled accesses per layer. */
-	for (layer_level = 0; layer_level < domain->num_layers; layer_level++) {
-		const unsigned long access_req = access_request;
-		unsigned long access_bit;
-
-		for_each_set_bit(access_bit, &access_req,
-				ARRAY_SIZE(*layer_masks)) {
-			if (landlock_get_fs_access_mask(domain, layer_level) &
-					BIT_ULL(access_bit)) {
-				(*layer_masks)[access_bit] |=
-					BIT_ULL(layer_level);
-				handled_accesses |= BIT_ULL(access_bit);
-			}
-		}
-	}
-	return handled_accesses;
-}
-
 /*
  * Check that a destination file hierarchy has more restrictions than a source
  * file hierarchy.  This is only used for link and rename actions.
@@ -506,7 +399,8 @@  static int check_access_path_dual(
 		 * a superset of the meaningful requested accesses).
 		 */
 		access_masked_parent1 = access_masked_parent2 =
-			get_handled_accesses(domain);
+			get_handled_accesses(domain, LANDLOCK_RULE_PATH_BENEATH,
+					     LANDLOCK_NUM_ACCESS_FS);
 		is_dom_check = true;
 	} else {
 		if (WARN_ON_ONCE(dentry_child1 || dentry_child2))
@@ -519,17 +413,25 @@  static int check_access_path_dual(

 	if (unlikely(dentry_child1)) {
 		unmask_layers(find_rule(domain, dentry_child1),
-			      init_layer_masks(domain, LANDLOCK_MASK_ACCESS_FS,
-					       &_layer_masks_child1),
-			      &_layer_masks_child1);
+				init_layer_masks(domain,
+					LANDLOCK_MASK_ACCESS_FS,
+					&_layer_masks_child1,
+					sizeof(_layer_masks_child1),
+					LANDLOCK_RULE_PATH_BENEATH),
+				&_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)) {
 		unmask_layers(find_rule(domain, dentry_child2),
-			      init_layer_masks(domain, LANDLOCK_MASK_ACCESS_FS,
-					       &_layer_masks_child2),
-			      &_layer_masks_child2);
+				init_layer_masks(domain,
+					LANDLOCK_MASK_ACCESS_FS,
+					&_layer_masks_child2,
+					sizeof(_layer_masks_child2),
+					LANDLOCK_RULE_PATH_BENEATH),
+				&_layer_masks_child2,
+				ARRAY_SIZE(_layer_masks_child2));
 		layer_masks_child2 = &_layer_masks_child2;
 		child2_is_directory = d_is_dir(dentry_child2);
 	}
@@ -582,14 +484,15 @@  static int check_access_path_dual(

 		rule = find_rule(domain, walker_path.dentry);
 		allowed_parent1 = unmask_layers(rule, access_masked_parent1,
-						layer_masks_parent1);
+				layer_masks_parent1,
+				ARRAY_SIZE(*layer_masks_parent1));
 		allowed_parent2 = unmask_layers(rule, access_masked_parent2,
-						layer_masks_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)) {
@@ -645,7 +548,9 @@  static inline int check_access_path(const struct landlock_ruleset *const domain,
 {
 	layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_FS] = {};

-	access_request = init_layer_masks(domain, access_request, &layer_masks);
+	access_request = init_layer_masks(domain, access_request,
+			&layer_masks, sizeof(layer_masks),
+			LANDLOCK_RULE_PATH_BENEATH);
 	return check_access_path_dual(domain, path, access_request,
 				      &layer_masks, NULL, 0, NULL, NULL);
 }
@@ -729,7 +634,8 @@  static bool collect_domain_accesses(
 		return true;

 	access_dom = init_layer_masks(domain, LANDLOCK_MASK_ACCESS_FS,
-				      layer_masks_dom);
+			layer_masks_dom, sizeof(*layer_masks_dom),
+			LANDLOCK_RULE_PATH_BENEATH);

 	dget(dir);
 	while (true) {
@@ -737,7 +643,8 @@  static bool collect_domain_accesses(

 		/* Gets all layers allowing all domain accesses. */
 		if (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.
@@ -851,9 +758,10 @@  static int current_check_refer_path(struct dentry *const old_dentry,
 		 * The LANDLOCK_ACCESS_FS_REFER access right is not required
 		 * for same-directory referer (i.e. no reparenting).
 		 */
-		access_request_parent1 = init_layer_masks(
-			dom, access_request_parent1 | access_request_parent2,
-			&layer_masks_parent1);
+		access_request_parent1 = init_layer_masks(dom,
+				access_request_parent1 | access_request_parent2,
+				&layer_masks_parent1, sizeof(layer_masks_parent1),
+				LANDLOCK_RULE_PATH_BENEATH);
 		return check_access_path_dual(dom, new_dir,
 					      access_request_parent1,
 					      &layer_masks_parent1, NULL, 0,
@@ -861,7 +769,9 @@  static int current_check_refer_path(struct dentry *const old_dentry,
 	}

 	/* Backward compatibility: no reparenting support. */
-	if (!(get_handled_accesses(dom) & LANDLOCK_ACCESS_FS_REFER))
+	if (!(get_handled_accesses(dom, LANDLOCK_RULE_PATH_BENEATH,
+				   LANDLOCK_NUM_ACCESS_FS) &
+						LANDLOCK_ACCESS_FS_REFER))
 		return -EXDEV;

 	access_request_parent1 |= LANDLOCK_ACCESS_FS_REFER;
diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
index 4b4c9953bb32..c4ed783d655b 100644
--- a/security/landlock/ruleset.c
+++ b/security/landlock/ruleset.c
@@ -233,7 +233,8 @@  static int insert_rule(struct landlock_ruleset *const ruleset,
 					       &(*layers)[0]);
 			if (IS_ERR(new_rule))
 				return PTR_ERR(new_rule);
-			rb_replace_node(&this->node, &new_rule->node, &ruleset->root_inode);
+			rb_replace_node(&this->node, &new_rule->node,
+					&ruleset->root_inode);
 			free_rule(this, rule_type);
 			break;
 		}
@@ -246,7 +247,8 @@  static int insert_rule(struct landlock_ruleset *const ruleset,
 		return -E2BIG;
 	switch (rule_type) {
 	case LANDLOCK_RULE_PATH_BENEATH:
-		new_rule = create_rule(object_ptr, 0, layers, num_layers, NULL);
+		new_rule = create_rule(object_ptr, 0, layers,
+				       num_layers, NULL);
 		if (IS_ERR(new_rule))
 			return PTR_ERR(new_rule);
 		rb_link_node(&new_rule->node, parent_node, walker_node);
@@ -281,8 +283,8 @@  int landlock_insert_rule(struct landlock_ruleset *const ruleset,
 	} };

 	build_check_layer();
-	return insert_rule(ruleset, object_ptr, object_data, rule_type, &layers,
-			   ARRAY_SIZE(layers));
+	return insert_rule(ruleset, object_ptr, object_data, rule_type,
+			   &layers, ARRAY_SIZE(layers));
 }

 static inline void get_hierarchy(struct landlock_hierarchy *const hierarchy)
@@ -335,8 +337,9 @@  static int tree_merge(struct landlock_ruleset *const src,

 		switch (rule_type) {
 		case LANDLOCK_RULE_PATH_BENEATH:
-			err = insert_rule(dst, walker_rule->object.ptr, 0, rule_type,
-					  &layers, ARRAY_SIZE(layers));
+			err = insert_rule(dst, walker_rule->object.ptr, 0,
+					  rule_type, &layers,
+					  ARRAY_SIZE(layers));
 			break;
 		}
 		if (err)
@@ -433,9 +436,13 @@  static int inherit_ruleset(struct landlock_ruleset *const parent,
 		err = -EINVAL;
 		goto out_unlock;
 	}
-	/* Copies the parent layer stack and leaves a space for the new layer. */
+	/*
+	 * Copies the parent layer stack and leaves a space
+	 * for the new layer.
+	 */
 	memcpy(child->access_masks, parent->access_masks,
-			flex_array_size(parent, access_masks, parent->num_layers));
+			flex_array_size(parent, access_masks,
+					parent->num_layers));

 	if (WARN_ON_ONCE(!parent->hierarchy)) {
 		err = -EINVAL;
@@ -455,8 +462,9 @@  static void free_ruleset(struct landlock_ruleset *const ruleset)
 	struct landlock_rule *freeme, *next;

 	might_sleep();
-	rbtree_postorder_for_each_entry_safe(freeme, next, &ruleset->root_inode,
-			node)
+	rbtree_postorder_for_each_entry_safe(freeme, next,
+					     &ruleset->root_inode,
+					     node)
 		free_rule(freeme, LANDLOCK_RULE_PATH_BENEATH);
 	put_hierarchy(ruleset->hierarchy);
 	kfree(ruleset);
@@ -577,3 +585,127 @@  const struct landlock_rule *landlock_find_rule(
 	}
 	return NULL;
 }
+
+access_mask_t get_handled_accesses(
+		const struct landlock_ruleset *const domain,
+		u16 rule_type, u16 num_access)
+{
+	access_mask_t access_dom = 0;
+	unsigned long access_bit;
+
+	switch (rule_type) {
+	case LANDLOCK_RULE_PATH_BENEATH:
+		for (access_bit = 0; access_bit < LANDLOCK_NUM_ACCESS_FS;
+			access_bit++) {
+			size_t layer_level;
+
+			for (layer_level = 0; layer_level < domain->num_layers;
+					layer_level++) {
+				if (landlock_get_fs_access_mask(domain,
+								layer_level) &
+						BIT_ULL(access_bit)) {
+					access_dom |= BIT_ULL(access_bit);
+					break;
+				}
+			}
+		}
+		break;
+	default:
+		break;
+	}
+	return access_dom;
+}
+
+/*
+ * @layer_masks is read and may be updated according to the access request and
+ * the matching rule.
+ *
+ * Returns true if the request is allowed (i.e. relevant layer masks for the
+ * request are empty).
+ */
+bool unmask_layers(const struct landlock_rule *const rule,
+		const access_mask_t access_request,
+		layer_mask_t (*const layer_masks)[], size_t masks_array_size)
+{
+	size_t layer_level;
+
+	if (!access_request || !layer_masks)
+		return true;
+	if (!rule)
+		return false;
+
+	/*
+	 * An access is granted if, for each policy layer, at least one rule
+	 * encountered on the pathwalk grants the requested access,
+	 * regardless of its position in the layer stack.  We must then check
+	 * the remaining layers for each inode, from the first added layer to
+	 * the last one.  When there is multiple requested accesses, for each
+	 * policy layer, the full set of requested accesses may not be granted
+	 * by only one rule, but by the union (binary OR) of multiple rules.
+	 * E.g. /a/b <execute> + /a <read> => /a/b <execute + read>
+	 */
+	for (layer_level = 0; layer_level < rule->num_layers; layer_level++) {
+		const struct landlock_layer *const layer =
+			&rule->layers[layer_level];
+		const layer_mask_t layer_bit = BIT_ULL(layer->level - 1);
+		const unsigned long access_req = access_request;
+		unsigned long access_bit;
+		bool is_empty;
+
+		/*
+		 * Records in @layer_masks which layer grants access to each
+		 * requested access.
+		 */
+		is_empty = true;
+		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];
+		}
+		if (is_empty)
+			return true;
+	}
+	return false;
+}
+
+access_mask_t init_layer_masks(const struct landlock_ruleset *const domain,
+			       const access_mask_t access_request,
+			       layer_mask_t (*const layer_masks)[],
+			       size_t masks_size,
+			       u16 rule_type)
+{
+	access_mask_t handled_accesses = 0;
+	size_t layer_level;
+
+	memset(layer_masks, 0, masks_size);
+
+	/* An empty access request can happen because of O_WRONLY | O_RDWR. */
+	if (!access_request)
+		return 0;
+
+	/* Saves all handled accesses per layer. */
+	for (layer_level = 0; layer_level < domain->num_layers;
+			layer_level++) {
+		const unsigned long access_req = access_request;
+		unsigned long access_bit;
+
+		switch (rule_type) {
+		case LANDLOCK_RULE_PATH_BENEATH:
+			for_each_set_bit(access_bit, &access_req,
+					LANDLOCK_NUM_ACCESS_FS) {
+				if (landlock_get_fs_access_mask(domain,
+								layer_level) &
+						BIT_ULL(access_bit)) {
+					(*layer_masks)[access_bit] |=
+						BIT_ULL(layer_level);
+					handled_accesses |=
+							   BIT_ULL(access_bit);
+				}
+			}
+			break;
+		default:
+			return 0;
+		}
+	}
+	return handled_accesses;
+}
diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h
index 3066e5d7180c..f3cd890d0348 100644
--- a/security/landlock/ruleset.h
+++ b/security/landlock/ruleset.h
@@ -195,7 +195,22 @@  static inline u32 landlock_get_fs_access_mask(
 					const struct landlock_ruleset *ruleset,
 					u16 mask_level)
 {
-	return ruleset->access_masks[mask_level];
+	return (ruleset->access_masks[mask_level] & LANDLOCK_MASK_ACCESS_FS);
 }

+access_mask_t get_handled_accesses(
+		const struct landlock_ruleset *const domain,
+		u16 rule_type, u16 num_access);
+
+bool unmask_layers(const struct landlock_rule *const rule,
+		   const access_mask_t access_request,
+		   layer_mask_t (*const layer_masks)[],
+		   size_t masks_array_size);
+
+access_mask_t init_layer_masks(const struct landlock_ruleset *const domain,
+			       const access_mask_t access_request,
+			       layer_mask_t (*const layer_masks)[],
+			       size_t masks_size,
+			       u16 rule_type);
+
 #endif /* _SECURITY_LANDLOCK_RULESET_H */