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Message-ID: <20231026014751.414649-7-konstantin.meskhidze@huawei.com> Date: Thu, 26 Oct 2023 09:47:45 +0800 From: Konstantin Meskhidze <konstantin.meskhidze@...wei.com> To: <mic@...ikod.net> CC: <willemdebruijn.kernel@...il.com>, <gnoack3000@...il.com>, <linux-security-module@...r.kernel.org>, <netdev@...r.kernel.org>, <netfilter-devel@...r.kernel.org>, <yusongping@...wei.com>, <artem.kuzin@...wei.com> Subject: [PATCH v14 06/12] landlock: Refactor layer helpers Add 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@...wei.com> Signed-off-by: Mickaël Salaün <mic@...ikod.net> --- Changes since v13: * Refactors commit message. Changes since v12: * None. Changes since v11: * None. Changes since v10: * Minor fix. Changes since v9: * Refactors commit message. Changes since v8: * None. Changes since v7: * Refactors commit message, adds a co-developer. * Minor fixes. 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 | 43 ++++++++++++++++++--------------- security/landlock/ruleset.c | 48 +++++++++++++++++++++++++------------ security/landlock/ruleset.h | 17 ++++++------- 3 files changed, 66 insertions(+), 42 deletions(-) diff --git a/security/landlock/fs.c b/security/landlock/fs.c index e6a19ff1765a..bc7c126deea2 100644 --- a/security/landlock/fs.c +++ b/security/landlock/fs.c @@ -442,20 +442,22 @@ static bool is_access_to_paths_allowed( } if (unlikely(dentry_child1)) { - landlock_unmask_layers(find_rule(domain, dentry_child1), - landlock_init_layer_masks( - domain, LANDLOCK_MASK_ACCESS_FS, - &_layer_masks_child1), - &_layer_masks_child1); + landlock_unmask_layers( + find_rule(domain, dentry_child1), + landlock_init_layer_masks( + domain, LANDLOCK_MASK_ACCESS_FS, + &_layer_masks_child1, LANDLOCK_KEY_INODE), + &_layer_masks_child1, ARRAY_SIZE(_layer_masks_child1)); layer_masks_child1 = &_layer_masks_child1; child1_is_directory = d_is_dir(dentry_child1); } if (unlikely(dentry_child2)) { - landlock_unmask_layers(find_rule(domain, dentry_child2), - landlock_init_layer_masks( - domain, LANDLOCK_MASK_ACCESS_FS, - &_layer_masks_child2), - &_layer_masks_child2); + landlock_unmask_layers( + find_rule(domain, dentry_child2), + landlock_init_layer_masks( + domain, LANDLOCK_MASK_ACCESS_FS, + &_layer_masks_child2, LANDLOCK_KEY_INODE), + &_layer_masks_child2, ARRAY_SIZE(_layer_masks_child2)); layer_masks_child2 = &_layer_masks_child2; child2_is_directory = d_is_dir(dentry_child2); } @@ -508,14 +510,15 @@ static bool is_access_to_paths_allowed( rule = find_rule(domain, walker_path.dentry); allowed_parent1 = landlock_unmask_layers( - rule, access_masked_parent1, layer_masks_parent1); + rule, access_masked_parent1, layer_masks_parent1, + ARRAY_SIZE(*layer_masks_parent1)); allowed_parent2 = landlock_unmask_layers( - rule, access_masked_parent2, layer_masks_parent2); + rule, access_masked_parent2, layer_masks_parent2, + ARRAY_SIZE(*layer_masks_parent2)); /* Stops when a rule from each layer grants access. */ if (allowed_parent1 && allowed_parent2) break; - jump_up: if (walker_path.dentry == walker_path.mnt->mnt_root) { if (follow_up(&walker_path)) { @@ -554,8 +557,8 @@ static inline int check_access_path(const struct landlock_ruleset *const domain, { layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_FS] = {}; - access_request = - landlock_init_layer_masks(domain, access_request, &layer_masks); + access_request = landlock_init_layer_masks( + domain, access_request, &layer_masks, LANDLOCK_KEY_INODE); if (is_access_to_paths_allowed(domain, path, access_request, &layer_masks, NULL, 0, NULL, NULL)) return 0; @@ -641,7 +644,8 @@ static bool collect_domain_accesses( return true; access_dom = landlock_init_layer_masks(domain, LANDLOCK_MASK_ACCESS_FS, - layer_masks_dom); + layer_masks_dom, + LANDLOCK_KEY_INODE); dget(dir); while (true) { @@ -649,7 +653,8 @@ static bool collect_domain_accesses( /* Gets all layers allowing all domain accesses. */ if (landlock_unmask_layers(find_rule(domain, dir), access_dom, - layer_masks_dom)) { + layer_masks_dom, + ARRAY_SIZE(*layer_masks_dom))) { /* * Stops when all handled accesses are allowed by at * least one rule in each layer. @@ -764,7 +769,7 @@ static int current_check_refer_path(struct dentry *const old_dentry, */ access_request_parent1 = landlock_init_layer_masks( dom, access_request_parent1 | access_request_parent2, - &layer_masks_parent1); + &layer_masks_parent1, LANDLOCK_KEY_INODE); if (is_access_to_paths_allowed( dom, new_dir, access_request_parent1, &layer_masks_parent1, NULL, 0, NULL, NULL)) @@ -1140,7 +1145,7 @@ static int hook_file_open(struct file *const file) if (is_access_to_paths_allowed( dom, &file->f_path, landlock_init_layer_masks(dom, full_access_request, - &layer_masks), + &layer_masks, LANDLOCK_KEY_INODE), &layer_masks, NULL, 0, NULL, NULL)) { allowed_access = full_access_request; } else { diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c index 28ffeedd21d6..e36c5c332242 100644 --- a/security/landlock/ruleset.c +++ b/security/landlock/ruleset.c @@ -573,14 +573,15 @@ landlock_find_rule(const struct landlock_ruleset *const ruleset, /* * @layer_masks is read and may be updated according to the access request and * the matching rule. + * @masks_array_size must be equal to ARRAY_SIZE(*layer_masks). * * Returns true if the request is allowed (i.e. relevant layer masks for the * request are empty). */ -bool landlock_unmask_layers( - const struct landlock_rule *const rule, - const access_mask_t access_request, - layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS]) +bool landlock_unmask_layers(const struct landlock_rule *const rule, + const access_mask_t access_request, + layer_mask_t (*const layer_masks)[], + const size_t masks_array_size) { size_t layer_level; @@ -612,8 +613,7 @@ bool landlock_unmask_layers( * requested access. */ is_empty = true; - for_each_set_bit(access_bit, &access_req, - ARRAY_SIZE(*layer_masks)) { + for_each_set_bit(access_bit, &access_req, masks_array_size) { if (layer->access & BIT_ULL(access_bit)) (*layer_masks)[access_bit] &= ~layer_bit; is_empty = is_empty && !(*layer_masks)[access_bit]; @@ -624,6 +624,10 @@ bool landlock_unmask_layers( return false; } +typedef access_mask_t +get_access_mask_t(const struct landlock_ruleset *const ruleset, + const u16 layer_level); + /** * landlock_init_layer_masks - Initialize layer masks from an access request * @@ -633,19 +637,34 @@ bool landlock_unmask_layers( * @domain: The domain that defines the current restrictions. * @access_request: The requested access rights to check. * @layer_masks: The layer masks to populate. + * @key_type: The key type to switch between access masks of different types. * * Returns: An access mask where each access right bit is set which is handled * in any of the active layers in @domain. */ -access_mask_t landlock_init_layer_masks( - const struct landlock_ruleset *const domain, - const access_mask_t access_request, - layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS]) +access_mask_t +landlock_init_layer_masks(const struct landlock_ruleset *const domain, + const access_mask_t access_request, + layer_mask_t (*const layer_masks)[], + const enum landlock_key_type key_type) { access_mask_t handled_accesses = 0; - size_t layer_level; + size_t layer_level, num_access; + get_access_mask_t *get_access_mask; + + switch (key_type) { + case LANDLOCK_KEY_INODE: + get_access_mask = landlock_get_fs_access_mask; + num_access = LANDLOCK_NUM_ACCESS_FS; + break; + default: + WARN_ON_ONCE(1); + return 0; + } + + memset(layer_masks, 0, + array_size(sizeof((*layer_masks)[0]), num_access)); - memset(layer_masks, 0, sizeof(*layer_masks)); /* An empty access request can happen because of O_WRONLY | O_RDWR. */ if (!access_request) return 0; @@ -655,10 +674,9 @@ access_mask_t landlock_init_layer_masks( const unsigned long access_req = access_request; unsigned long access_bit; - for_each_set_bit(access_bit, &access_req, - ARRAY_SIZE(*layer_masks)) { + for_each_set_bit(access_bit, &access_req, num_access) { if (BIT_ULL(access_bit) & - landlock_get_fs_access_mask(domain, layer_level)) { + get_access_mask(domain, layer_level)) { (*layer_masks)[access_bit] |= BIT_ULL(layer_level); handled_accesses |= BIT_ULL(access_bit); diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h index 3a7f03b39d4f..1ede2b9a79b7 100644 --- a/security/landlock/ruleset.h +++ b/security/landlock/ruleset.h @@ -266,14 +266,15 @@ landlock_get_fs_access_mask(const struct landlock_ruleset *const ruleset, return landlock_get_raw_fs_access_mask(ruleset, layer_level) | LANDLOCK_ACCESS_FS_INITIALLY_DENIED; } -bool landlock_unmask_layers( - const struct landlock_rule *const rule, - const access_mask_t access_request, - layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS]); +bool landlock_unmask_layers(const struct landlock_rule *const rule, + const access_mask_t access_request, + layer_mask_t (*const layer_masks)[], + const size_t masks_array_size); -access_mask_t landlock_init_layer_masks( - const struct landlock_ruleset *const domain, - const access_mask_t access_request, - layer_mask_t (*const layer_masks)[LANDLOCK_NUM_ACCESS_FS]); +access_mask_t +landlock_init_layer_masks(const struct landlock_ruleset *const domain, + const access_mask_t access_request, + layer_mask_t (*const layer_masks)[], + const enum landlock_key_type key_type); #endif /* _SECURITY_LANDLOCK_RULESET_H */ -- 2.25.1
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