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

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

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@xxxxxxxxxx>
>
> As for patch 2/18, you can append:
> Co-developed-by: Mickaël Salaün <mic@xxxxxxxxxxx>

  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
> .