On 17/03/2022 15:29, Konstantin Meskhidze wrote:
3/16/2022 11:27 AM, Mickaël Salaün пишет:
On 09/03/2022 14:44, Konstantin Meskhidze wrote:
A new object union added to support a socket port
rule type. To support it landlock_insert_rule() and
landlock_find_rule() were refactored. Now adding
or searching a rule in a ruleset depends on a
rule_type argument provided in refactored
functions mentioned above.
Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@xxxxxxxxxx>
---
Changes since v3:
* Split commit.
* Refactoring landlock_insert_rule and landlock_find_rule functions.
* Rename new_ruleset->root_inode.
---
security/landlock/fs.c | 5 +-
security/landlock/ruleset.c | 108 +++++++++++++++++++++++++-----------
security/landlock/ruleset.h | 26 +++++----
3 files changed, 94 insertions(+), 45 deletions(-)
diff --git a/security/landlock/fs.c b/security/landlock/fs.c
index 97f5c455f5a7..1497948d754f 100644
--- a/security/landlock/fs.c
+++ b/security/landlock/fs.c
@@ -168,7 +168,7 @@ int landlock_append_fs_rule(struct
landlock_ruleset *const ruleset,
if (IS_ERR(object))
return PTR_ERR(object);
mutex_lock(&ruleset->lock);
- err = landlock_insert_rule(ruleset, object, access_rights);
+ err = landlock_insert_rule(ruleset, object, 0, access_rights,
LANDLOCK_RULE_PATH_BENEATH);
For consistency, please use 80 columns everywhere.
Ok. I got it.
mutex_unlock(&ruleset->lock);
/*
* No need to check for an error because landlock_insert_rule()
@@ -195,7 +195,8 @@ static inline u64 unmask_layers(
inode = d_backing_inode(path->dentry);
rcu_read_lock();
rule = landlock_find_rule(domain,
- rcu_dereference(landlock_inode(inode)->object));
+ (uintptr_t)rcu_dereference(landlock_inode(inode)->object),
+ LANDLOCK_RULE_PATH_BENEATH);
rcu_read_unlock();
if (!rule)
return layer_mask;
diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
index a6212b752549..971685c48641 100644
--- a/security/landlock/ruleset.c
+++ b/security/landlock/ruleset.c
@@ -34,7 +34,7 @@ static struct landlock_ruleset
*create_ruleset(const u32 num_layers)
return ERR_PTR(-ENOMEM);
refcount_set(&new_ruleset->usage, 1);
mutex_init(&new_ruleset->lock);
- new_ruleset->root = RB_ROOT;
+ new_ruleset->root_inode = RB_ROOT;
new_ruleset->num_layers = num_layers;
/*
* hierarchy = NULL
@@ -81,10 +81,12 @@ static void build_check_rule(void)
}
static struct landlock_rule *create_rule(
- struct landlock_object *const object,
+ struct landlock_object *const object_ptr,
+ const uintptr_t object_data,
const struct landlock_layer (*const layers)[],
const u32 num_layers,
- const struct landlock_layer *const new_layer)
+ const struct landlock_layer *const new_layer,
+ const u16 rule_type)
{
struct landlock_rule *new_rule;
u32 new_num_layers;
@@ -103,8 +105,16 @@ static struct landlock_rule *create_rule(
if (!new_rule)
return ERR_PTR(-ENOMEM);
RB_CLEAR_NODE(&new_rule->node);
- landlock_get_object(object);
- new_rule->object = object;
+
+ switch (rule_type) {
+ case LANDLOCK_RULE_PATH_BENEATH:
+ landlock_get_object(object_ptr);
+ new_rule->object.ptr = object_ptr;
+ break;
+ default:
+ return ERR_PTR(-EINVAL);
This would lead to memory leak. You should at least add a
WARN_ON_ONCE(1) here, but a proper solution would be to remove the use
of rule_type and only rely on object_ptr and object_data values. You
can also add a WARN_ON_ONCE(object_ptr && object_data).
But rule_type is needed here in coming commits to support network
rules. For LANDLOCK_RULE_PATH_BENEATH rule type landlock_get_object()
is used but for LANDLOCK_RULE_NET_SERVICE is not. Using rule type is
convenient for distinguising between fs and network rules.
rule_type is not required to infer if the rule use a pointer or raw
data, even with the following commits, because you can rely on
object_ptr being NULL or not. This would make create_rule() generic for
pointer-based and data-based object, even if not-yet-existing rule
types. It is less error-prone to only be able to infer something from
one source (i.e. object_ptr and not rule_type).
+ }
+
new_rule->num_layers = new_num_layers;
/* Copies the original layer stack. */
memcpy(new_rule->layers, layers,
@@ -120,7 +130,7 @@ static void free_rule(struct landlock_rule *const
rule)
might_sleep();
if (!rule)
return;
- landlock_put_object(rule->object);
+ landlock_put_object(rule->object.ptr);
kfree(rule);
}
@@ -156,26 +166,38 @@ static void build_check_ruleset(void)
* access rights.
*/
static int insert_rule(struct landlock_ruleset *const ruleset,
- struct landlock_object *const object,
+ struct landlock_object *const object_ptr,
+ const uintptr_t object_data,
Can you move rule_type here for this function and similar ones? It makes
sense to group object-related arguments.
const struct landlock_layer (*const layers)[],
- size_t num_layers)
+ size_t num_layers, u16 rule_type)
{
struct rb_node **walker_node;
struct rb_node *parent_node = NULL;
struct landlock_rule *new_rule;
+ uintptr_t object;
+ struct rb_root *root;
might_sleep();
lockdep_assert_held(&ruleset->lock);
- if (WARN_ON_ONCE(!object || !layers))
- return -ENOENT;
You can leave this code here.
But anyway in coming commits with network rules this code will be
moved into case LANDLOCK_RULE_PATH_BENEATH: ....
Yes, but without rule_type you don't need to duplicate this check, just
to remove object_ptr from WARN_ON_ONCE() and replace the rule_type
switch/case with if (object_ptr).
You can change to this:
--- a/security/landlock/ruleset.c
+++ b/security/landlock/ruleset.c
@@ -194,43 +194,49 @@ static void build_check_ruleset(void)
*/
static int insert_rule(struct landlock_ruleset *const ruleset,
struct landlock_object *const object_ptr,
- const uintptr_t object_data,
+ uintptr_t object_data, /* move @rule_type here */
const struct landlock_layer (*const layers)[],
- size_t num_layers, u16 rule_type)
+ size_t num_layers, const enum landlock_rule_type rule_type)
{
struct rb_node **walker_node;
struct rb_node *parent_node = NULL;
struct landlock_rule *new_rule;
- uintptr_t object;
struct rb_root *root;
might_sleep();
lockdep_assert_held(&ruleset->lock);
- /* Choose rb_tree structure depending on a rule type */
+
+ if (WARN_ON_ONCE(!layers))
+ return -ENOENT;
+ if (WARN_ON_ONCE(object_ptr && object_data))
+ return -EINVAL;
+
+ /* Chooses the rb_tree according to the rule type. */
switch (rule_type) {
case LANDLOCK_RULE_PATH_BENEATH:
- if (WARN_ON_ONCE(!object_ptr || !layers))
+ if (WARN_ON_ONCE(!object_ptr))
return -ENOENT;
- object = (uintptr_t)object_ptr;
+ object_data = (uintptr_t)object_ptr;
root = &ruleset->root_inode;
break;
case LANDLOCK_RULE_NET_SERVICE:
- if (WARN_ON_ONCE(!object_data || !layers))
- return -ENOENT;
- object = object_data;
+ if (WARN_ON_ONCE(object_ptr))
+ return -EINVAL;
root = &ruleset->root_net_port;
break;
default:
+ WARN_ON_ONCE(1);
return -EINVAL;
}
+
walker_node = &root->rb_node;
while (*walker_node) {
struct landlock_rule *const this = rb_entry(*walker_node,
struct landlock_rule, node);
- if (this->object.data != object) {
+ if (this->object.data != object_data) {
parent_node = *walker_node;
- if (this->object.data < object)
+ if (this->object.data < object_data)
walker_node = &((*walker_node)->rb_right);
else
walker_node = &((*walker_node)->rb_left);
This highlight an implicit error handling for a port value of 0. I'm not
sure if this should be allowed or not though. If not, it should be an
explicit service_port check in add_rule_net_service(). A data value of
zero might be legitimate for this use case or not-yet-existing
data-based rule types. Anyway, this kind of check is specific to the use
case and should not be part of insert_rule().
- walker_node = &(ruleset->root.rb_node);
+ /* Choose rb_tree structure depending on a rule type */
+ switch (rule_type) {
+ case LANDLOCK_RULE_PATH_BENEATH:
+ if (WARN_ON_ONCE(!object_ptr || !layers))
+ return -ENOENT;
+ object = (uintptr_t)object_ptr;
+ root = &ruleset->root_inode;
+ break;
+ default:
+ return -EINVAL;
+ }
+ walker_node = &root->rb_node;
while (*walker_node) {
struct landlock_rule *const this = rb_entry(*walker_node,
struct landlock_rule, node);
- if (this->object != object) {
+ if (this->object.data != object) {
parent_node = *walker_node;
- if (this->object < object)
+ if (this->object.data < object)
walker_node = &((*walker_node)->rb_right);
else
walker_node = &((*walker_node)->rb_left);
@@ -207,11 +229,15 @@ static int insert_rule(struct landlock_ruleset
*const ruleset,
* Intersects access rights when it is a merge between a
* ruleset and a domain.
*/
- new_rule = create_rule(object, &this->layers, this->num_layers,
- &(*layers)[0]);
+ switch (rule_type) {
+ case LANDLOCK_RULE_PATH_BENEATH:
Same here and for the following code, you should replace such
switch/case with an if (object_ptr).
What about coming commits with network rule_type support?
This will still works.
+ new_rule = create_rule(object_ptr, 0, &this->layers,
this->num_layers,
+ &(*layers)[0], rule_type);
+ break;
+ }
if (IS_ERR(new_rule))
return PTR_ERR(new_rule);
- rb_replace_node(&this->node, &new_rule->node, &ruleset->root);
+ rb_replace_node(&this->node, &new_rule->node,
&ruleset->root_inode);
Use the root variable here. Same for the following code and patches.
What about your suggestion to use 2 rb_tress to support different
rule_types:
1. root_inode - for filesystem objects
2. root_net_port - for network port objects
????
I was talking about the root variable you declared a few line before.
The conversion from ruleset->root to ruleset->root_inode is fine.
[...]
@@ -465,20 +501,28 @@ struct landlock_ruleset *landlock_merge_ruleset(
*/
const struct landlock_rule *landlock_find_rule(
const struct landlock_ruleset *const ruleset,
- const struct landlock_object *const object)
+ const uintptr_t object_data, const u16 rule_type)
{
const struct rb_node *node;
- if (!object)
+ if (!object_data)
object_data can be 0. You need to add a test with such value.
We need to be sure that this change cannot affect the current FS code.
I got it. I will refactor it.
Well, 0 means a port 0, which might not be correct, but this check
should not be performed by landlock_merge_ruleset().
return NULL;
- node = ruleset->root.rb_node;
+
+ switch (rule_type) {
+ case LANDLOCK_RULE_PATH_BENEATH:
+ node = ruleset->root_inode.rb_node;
+ break;
+ default:
+ return ERR_PTR(-EINVAL);
This is a bug. There is no check for such value. You need to check and
update all call sites to catch such errors. Same for all new use of
ERR_PTR().
Sorry, I did not get your point.
Do you mean I should check the correctness of rule_type in above
function which calls landlock_find_rule() ??? Why can't I add such check
here?
landlock_find_rule() only returns NULL or a valid pointer, not an error.
[...]
