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Date: Tue, 21 Jun 2022 16:23:01 +0800
From: Konstantin Meskhidze <konstantin.meskhidze@...wei.com>
To: <mic@...ikod.net>
CC: <willemdebruijn.kernel@...il.com>,
<linux-security-module@...r.kernel.org>, <netdev@...r.kernel.org>,
<netfilter-devel@...r.kernel.org>, <yusongping@...wei.com>,
<anton.sirazetdinov@...wei.com>
Subject: [PATCH v6 05/17] landlock: refactors helper functions
Adds new rule_type argument to
unmask_layers(), init_layer_masks() and
get_handled_accesses() helper functions.
This modification supports implementing new rule
types in the next landlock versions.
Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@...wei.com>
---
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 | 45 ++++++++++++++++---------
security/landlock/ruleset.c | 67 +++++++++++++++++++++++--------------
security/landlock/ruleset.h | 16 +++++----
3 files changed, 80 insertions(+), 48 deletions(-)
diff --git a/security/landlock/fs.c b/security/landlock/fs.c
index 42fb02141b9c..10f6c67f5c3b 100644
--- a/security/landlock/fs.c
+++ b/security/landlock/fs.c
@@ -400,7 +400,8 @@ 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))
@@ -414,16 +415,22 @@ 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,
+ 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);
+ &_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);
}
@@ -475,15 +482,16 @@ 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)) {
@@ -539,7 +547,9 @@ 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);
}
@@ -623,7 +633,8 @@ 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) {
@@ -631,7 +642,8 @@ 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.
@@ -747,7 +759,8 @@ 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, sizeof(layer_masks_parent1),
+ LANDLOCK_RULE_PATH_BENEATH);
return check_access_path_dual(dom, new_dir,
access_request_parent1,
&layer_masks_parent1, NULL, 0,
@@ -755,7 +768,9 @@ 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 32ec79d6559a..cbca85f5cc6d 100644
--- a/security/landlock/ruleset.c
+++ b/security/landlock/ruleset.c
@@ -578,23 +578,31 @@ landlock_find_rule(const struct landlock_ruleset *const ruleset,
return NULL;
}
-access_mask_t get_handled_accesses(const struct landlock_ruleset *const domain)
+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;
- 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;
+ 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;
}
@@ -608,7 +616,7 @@ access_mask_t get_handled_accesses(const struct landlock_ruleset *const domain)
*/
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)[], size_t masks_array_size)
{
size_t layer_level;
@@ -640,8 +648,7 @@ 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];
@@ -652,15 +659,16 @@ 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])
+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, sizeof(*layer_masks));
+ memset(layer_masks, 0, masks_size);
+
/* An empty access request can happen because of O_WRONLY | O_RDWR. */
if (!access_request)
return 0;
@@ -670,14 +678,21 @@ 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) &
- BIT_ULL(access_bit)) {
- (*layer_masks)[access_bit] |=
- BIT_ULL(layer_level);
- handled_accesses |= BIT_ULL(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 ea09ab2f27c4..c1cf7cce2cb5 100644
--- a/security/landlock/ruleset.h
+++ b/security/landlock/ruleset.h
@@ -193,18 +193,20 @@ 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);
+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)[LANDLOCK_NUM_ACCESS_FS]);
+ 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)[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)[],
+ size_t masks_size, u16 rule_type);
#endif /* _SECURITY_LANDLOCK_RULESET_H */
--
2.25.1
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