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landlock: Refactor layer helpers
Add a new key_type argument to the landlock_init_layer_masks() helper. Add a masks_array_size argument to the landlock_unmask_layers() helper. These modifications support implementing new rule types in the next Landlock versions. Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com> Link: https://lore.kernel.org/r/20231026014751.414649-7-konstantin.meskhidze@huawei.com Signed-off-by: Mickaël Salaün <mic@digikod.net>
This commit is contained in:
Konstantin Meskhidze
Mickaël Salaün
parent
0e74101129
commit
7a11275c37
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@ -442,20 +442,22 @@ static bool is_access_to_paths_allowed(
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}
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if (unlikely(dentry_child1)) {
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landlock_unmask_layers(find_rule(domain, dentry_child1),
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landlock_init_layer_masks(
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domain, LANDLOCK_MASK_ACCESS_FS,
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&_layer_masks_child1),
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&_layer_masks_child1);
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landlock_unmask_layers(
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find_rule(domain, dentry_child1),
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landlock_init_layer_masks(
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domain, LANDLOCK_MASK_ACCESS_FS,
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&_layer_masks_child1, LANDLOCK_KEY_INODE),
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&_layer_masks_child1, ARRAY_SIZE(_layer_masks_child1));
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layer_masks_child1 = &_layer_masks_child1;
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child1_is_directory = d_is_dir(dentry_child1);
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}
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if (unlikely(dentry_child2)) {
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landlock_unmask_layers(find_rule(domain, dentry_child2),
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landlock_init_layer_masks(
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domain, LANDLOCK_MASK_ACCESS_FS,
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&_layer_masks_child2),
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&_layer_masks_child2);
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landlock_unmask_layers(
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find_rule(domain, dentry_child2),
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landlock_init_layer_masks(
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domain, LANDLOCK_MASK_ACCESS_FS,
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&_layer_masks_child2, LANDLOCK_KEY_INODE),
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&_layer_masks_child2, ARRAY_SIZE(_layer_masks_child2));
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layer_masks_child2 = &_layer_masks_child2;
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child2_is_directory = d_is_dir(dentry_child2);
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}
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@ -508,14 +510,15 @@ static bool is_access_to_paths_allowed(
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rule = find_rule(domain, walker_path.dentry);
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allowed_parent1 = landlock_unmask_layers(
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rule, access_masked_parent1, layer_masks_parent1);
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rule, access_masked_parent1, layer_masks_parent1,
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ARRAY_SIZE(*layer_masks_parent1));
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allowed_parent2 = landlock_unmask_layers(
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rule, access_masked_parent2, layer_masks_parent2);
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rule, access_masked_parent2, layer_masks_parent2,
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ARRAY_SIZE(*layer_masks_parent2));
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/* Stops when a rule from each layer grants access. */
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if (allowed_parent1 && allowed_parent2)
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break;
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jump_up:
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if (walker_path.dentry == walker_path.mnt->mnt_root) {
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if (follow_up(&walker_path)) {
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@ -554,8 +557,8 @@ static inline int check_access_path(const struct landlock_ruleset *const domain,
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{
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layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_FS] = {};
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access_request =
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landlock_init_layer_masks(domain, access_request, &layer_masks);
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access_request = landlock_init_layer_masks(
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domain, access_request, &layer_masks, LANDLOCK_KEY_INODE);
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if (is_access_to_paths_allowed(domain, path, access_request,
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&layer_masks, NULL, 0, NULL, NULL))
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return 0;
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@ -641,7 +644,8 @@ static bool collect_domain_accesses(
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return true;
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access_dom = landlock_init_layer_masks(domain, LANDLOCK_MASK_ACCESS_FS,
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layer_masks_dom);
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layer_masks_dom,
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LANDLOCK_KEY_INODE);
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dget(dir);
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while (true) {
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@ -649,7 +653,8 @@ static bool collect_domain_accesses(
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/* Gets all layers allowing all domain accesses. */
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if (landlock_unmask_layers(find_rule(domain, dir), access_dom,
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layer_masks_dom)) {
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layer_masks_dom,
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ARRAY_SIZE(*layer_masks_dom))) {
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/*
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* Stops when all handled accesses are allowed by at
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* least one rule in each layer.
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@ -764,7 +769,7 @@ static int current_check_refer_path(struct dentry *const old_dentry,
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*/
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access_request_parent1 = landlock_init_layer_masks(
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dom, access_request_parent1 | access_request_parent2,
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&layer_masks_parent1);
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&layer_masks_parent1, LANDLOCK_KEY_INODE);
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if (is_access_to_paths_allowed(
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dom, new_dir, access_request_parent1,
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&layer_masks_parent1, NULL, 0, NULL, NULL))
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@ -1140,7 +1145,7 @@ static int hook_file_open(struct file *const file)
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if (is_access_to_paths_allowed(
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dom, &file->f_path,
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landlock_init_layer_masks(dom, full_access_request,
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&layer_masks),
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&layer_masks, LANDLOCK_KEY_INODE),
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&layer_masks, NULL, 0, NULL, NULL)) {
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allowed_access = full_access_request;
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} else {
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@ -573,14 +573,15 @@ landlock_find_rule(const struct landlock_ruleset *const ruleset,
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/*
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* @layer_masks is read and may be updated according to the access request and
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* the matching rule.
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* @masks_array_size must be equal to ARRAY_SIZE(*layer_masks).
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*
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* Returns true if the request is allowed (i.e. relevant layer masks for the
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* request are empty).
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*/
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bool landlock_unmask_layers(
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const struct landlock_rule *const rule,
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const access_mask_t access_request,
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layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS])
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bool landlock_unmask_layers(const struct landlock_rule *const rule,
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const access_mask_t access_request,
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layer_mask_t (*const layer_masks)[],
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const size_t masks_array_size)
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{
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size_t layer_level;
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@ -612,8 +613,7 @@ bool landlock_unmask_layers(
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* requested access.
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*/
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is_empty = true;
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for_each_set_bit(access_bit, &access_req,
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ARRAY_SIZE(*layer_masks)) {
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for_each_set_bit(access_bit, &access_req, masks_array_size) {
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if (layer->access & BIT_ULL(access_bit))
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(*layer_masks)[access_bit] &= ~layer_bit;
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is_empty = is_empty && !(*layer_masks)[access_bit];
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@ -624,6 +624,10 @@ bool landlock_unmask_layers(
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return false;
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}
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typedef access_mask_t
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get_access_mask_t(const struct landlock_ruleset *const ruleset,
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const u16 layer_level);
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/**
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* landlock_init_layer_masks - Initialize layer masks from an access request
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*
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@ -633,19 +637,34 @@ bool landlock_unmask_layers(
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* @domain: The domain that defines the current restrictions.
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* @access_request: The requested access rights to check.
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* @layer_masks: The layer masks to populate.
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* @key_type: The key type to switch between access masks of different types.
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*
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* Returns: An access mask where each access right bit is set which is handled
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* in any of the active layers in @domain.
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*/
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access_mask_t landlock_init_layer_masks(
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const struct landlock_ruleset *const domain,
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const access_mask_t access_request,
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layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS])
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access_mask_t
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landlock_init_layer_masks(const struct landlock_ruleset *const domain,
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const access_mask_t access_request,
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layer_mask_t (*const layer_masks)[],
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const enum landlock_key_type key_type)
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{
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access_mask_t handled_accesses = 0;
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size_t layer_level;
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size_t layer_level, num_access;
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get_access_mask_t *get_access_mask;
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switch (key_type) {
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case LANDLOCK_KEY_INODE:
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get_access_mask = landlock_get_fs_access_mask;
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num_access = LANDLOCK_NUM_ACCESS_FS;
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break;
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default:
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WARN_ON_ONCE(1);
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return 0;
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}
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memset(layer_masks, 0,
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array_size(sizeof((*layer_masks)[0]), num_access));
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memset(layer_masks, 0, sizeof(*layer_masks));
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/* An empty access request can happen because of O_WRONLY | O_RDWR. */
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if (!access_request)
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return 0;
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@ -655,10 +674,9 @@ access_mask_t landlock_init_layer_masks(
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const unsigned long access_req = access_request;
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unsigned long access_bit;
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for_each_set_bit(access_bit, &access_req,
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ARRAY_SIZE(*layer_masks)) {
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for_each_set_bit(access_bit, &access_req, num_access) {
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if (BIT_ULL(access_bit) &
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landlock_get_fs_access_mask(domain, layer_level)) {
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get_access_mask(domain, layer_level)) {
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(*layer_masks)[access_bit] |=
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BIT_ULL(layer_level);
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handled_accesses |= BIT_ULL(access_bit);
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@ -267,14 +267,15 @@ landlock_get_fs_access_mask(const struct landlock_ruleset *const ruleset,
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LANDLOCK_ACCESS_FS_INITIALLY_DENIED;
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}
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bool landlock_unmask_layers(
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const struct landlock_rule *const rule,
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const access_mask_t access_request,
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layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS]);
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bool landlock_unmask_layers(const struct landlock_rule *const rule,
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const access_mask_t access_request,
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layer_mask_t (*const layer_masks)[],
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const size_t masks_array_size);
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access_mask_t landlock_init_layer_masks(
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const struct landlock_ruleset *const domain,
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const access_mask_t access_request,
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layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS]);
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access_mask_t
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landlock_init_layer_masks(const struct landlock_ruleset *const domain,
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const access_mask_t access_request,
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layer_mask_t (*const layer_masks)[],
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const enum landlock_key_type key_type);
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#endif /* _SECURITY_LANDLOCK_RULESET_H */
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