Re: [PATCH v7 05/18] landlock: refactor helper functions

["Konstantin Meskhidze (A)" <konstantin.meskhidze@huawei.com>]

9/6/2022 11:07 AM, Mickaël Salaün пишет:
> You can improve the subject with: "landlock: Refactor unmask_layers()
> and init_layer_masks()"

   Got it. I will change it.
> 
> On 29/08/2022 19:03, Konstantin Meskhidze wrote:
>> Adds new key_type argument to init_layer_masks() helper functions.
>> This modification supports implementing new rule types in the next
>> Landlock versions.
>> 
>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>
> 
> As for patch 2/18, you can append:
> Co-developed-by: Mickaël Salaün <mic@digikod.net>

   Ok. I will append. Thanks.>
> 
>> ---
>> 
>> Changes since v6:
>> * Removes masks_size attribute from init_layer_masks().
>> * Refactors init_layer_masks() with new landlock_key_type.
>> 
>> Changes since v5:
>> * Splits commit.
>> * Formats code with clang-format-14.
>> 
>> Changes since v4:
>> * Refactors init_layer_masks(), get_handled_accesses()
>> and unmask_layers() functions to support multiple rule types.
>> * Refactors landlock_get_fs_access_mask() function with
>> LANDLOCK_MASK_ACCESS_FS mask.
>> 
>> Changes since v3:
>> * Splits commit.
>> * Refactors landlock_unmask_layers functions.
>> 
>> ---
>>   security/landlock/fs.c      | 33 +++++++++++++++++-----------
>>   security/landlock/ruleset.c | 44 +++++++++++++++++++++++++++----------
>>   security/landlock/ruleset.h | 11 +++++-----
>>   3 files changed, 58 insertions(+), 30 deletions(-)
>> 
>> diff --git a/security/landlock/fs.c b/security/landlock/fs.c
>> index b03d6153f628..a4d9aea539cd 100644
>> --- a/security/landlock/fs.c
>> +++ b/security/landlock/fs.c
>> @@ -439,16 +439,20 @@ 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);
>> +					       &_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)) {
>>   		unmask_layers(find_rule(domain, dentry_child2),
>>   			      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);
>>   	}
>> @@ -500,15 +504,16 @@ static int check_access_path_dual(
>>   		}
>> 
>>   		rule = find_rule(domain, walker_path.dentry);
>> -		allowed_parent1 = unmask_layers(rule, access_masked_parent1,
>> -						layer_masks_parent1);
>> -		allowed_parent2 = unmask_layers(rule, access_masked_parent2,
>> -						layer_masks_parent2);
>> +		allowed_parent1 = unmask_layers(
>> +			rule, access_masked_parent1, layer_masks_parent1,
>> +			ARRAY_SIZE(*layer_masks_parent1));
>> +		allowed_parent2 = unmask_layers(
>> +			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)) {
>> @@ -564,7 +569,8 @@ 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,
>> +					  LANDLOCK_KEY_INODE);
>>   	return check_access_path_dual(domain, path, access_request,
>>   				      &layer_masks, NULL, 0, NULL, NULL);
>>   }
>> @@ -648,7 +654,7 @@ static bool collect_domain_accesses(
>>   		return true;
>> 
>>   	access_dom = init_layer_masks(domain, LANDLOCK_MASK_ACCESS_FS,
>> -				      layer_masks_dom);
>> +				      layer_masks_dom, LANDLOCK_KEY_INODE);
>> 
>>   	dget(dir);
>>   	while (true) {
>> @@ -656,7 +662,8 @@ 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.
>> @@ -772,7 +779,7 @@ static int current_check_refer_path(struct dentry *const old_dentry,
>>   		 */
>>   		access_request_parent1 = init_layer_masks(
>>   			dom, access_request_parent1 | access_request_parent2,
>> -			&layer_masks_parent1);
>> +			&layer_masks_parent1, LANDLOCK_KEY_INODE);
>>   		return check_access_path_dual(dom, new_dir,
>>   					      access_request_parent1,
>>   					      &layer_masks_parent1, NULL, 0,
>> diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
>> index 671a95e2a345..84fcd8eb30d4 100644
>> --- a/security/landlock/ruleset.c
>> +++ b/security/landlock/ruleset.c
>> @@ -574,7 +574,8 @@ landlock_find_rule(const struct landlock_ruleset *const ruleset,
>>    */
> 
> You missed another hunk from my patch… Please do a diff with it.

   Sorry. What did I miss here?
> 
> 
>>   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])
>> +		   layer_mask_t (*const layer_masks)[],
>> +		   const size_t masks_array_size)
>>   {
>>   	size_t layer_level;
>> 
>> @@ -606,8 +607,7 @@ bool unmask_layers(const struct landlock_rule *const rule,
>>   		 * 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];
>> @@ -618,15 +618,36 @@ bool unmask_layers(const struct landlock_rule *const rule,
>>   	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)[LANDLOCK_NUM_ACCESS_FS])
>> +typedef access_mask_t
>> +get_access_mask_t(const struct landlock_ruleset *const ruleset,
>> +		  const u16 layer_level);
>> +
>> +/*
>> + * @layer_masks must contain LANDLOCK_NUM_ACCESS_FS or LANDLOCK_NUM_ACCESS_NET
>> + * elements according to @key_type.
>> + */
>> +access_mask_t init_layer_masks(const struct landlock_ruleset *const domain,
>> +			       const access_mask_t access_request,
>> +			       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;
>> @@ -636,9 +657,8 @@ init_layer_masks(const struct landlock_ruleset *const domain,
>>   		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) &
>> +		for_each_set_bit(access_bit, &access_req, num_access) {
>> +			if (get_access_mask(domain, layer_level) &
>>   			    BIT_ULL(access_bit)) {
>>   				(*layer_masks)[access_bit] |=
>>   					BIT_ULL(layer_level);
>> diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h
>> index d7d9b987829c..2083855bf42d 100644
>> --- a/security/landlock/ruleset.h
>> +++ b/security/landlock/ruleset.h
>> @@ -238,11 +238,12 @@ landlock_get_fs_access_mask(const struct landlock_ruleset *const ruleset,
>> 
>>   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]);
>> +		   layer_mask_t (*const layer_masks)[],
>> +		   const 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)[LANDLOCK_NUM_ACCESS_FS]);
>> +access_mask_t init_layer_masks(const struct landlock_ruleset *const domain,
>> +			       const access_mask_t access_request,
>> +			       layer_mask_t (*const layer_masks)[],
>> +			       const enum landlock_key_type key_type);
>> 
>>   #endif /* _SECURITY_LANDLOCK_RULESET_H */
>> --
>> 2.25.1
>> 
> .