[PATCH v7 08/18] landlock: add network rules support
Konstantin Meskhidze
konstantin.meskhidze at huawei.com
Mon Aug 29 17:03:51 UTC 2022
This commit adds network rules support in internal landlock functions
(presented in ruleset.c) and landlock_create_ruleset syscall.
Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze at huawei.com>
---
Changes since v6:
* Renames landlock_set_net_access_mask() to landlock_add_net_access_mask()
because it OR values.
* Makes landlock_add_net_access_mask() more resilient incorrect values.
* Refactors landlock_get_net_access_mask().
* Renames LANDLOCK_MASK_SHIFT_NET to LANDLOCK_SHIFT_ACCESS_NET and use
LANDLOCK_NUM_ACCESS_FS as value.
* Updates access_masks_t to u32 to support network access actions.
* Refactors landlock internal functions to support network actions with
landlock_key/key_type/id types.
Changes since v5:
* Gets rid of partial revert from landlock_add_rule
syscall.
* Formats code with clang-format-14.
Changes since v4:
* Refactors landlock_create_ruleset() - splits ruleset and
masks checks.
* Refactors landlock_create_ruleset() and landlock mask
setters/getters to support two rule types.
* Refactors landlock_add_rule syscall add_rule_path_beneath
function by factoring out get_ruleset_from_fd() and
landlock_put_ruleset().
Changes since v3:
* Splits commit.
* Adds network rule support for internal landlock functions.
* Adds set_mask and get_mask for network.
* Adds rb_root root_net_port.
---
security/landlock/limits.h | 6 +++++-
security/landlock/ruleset.c | 38 +++++++++++++++++++++++++++++----
security/landlock/ruleset.h | 41 ++++++++++++++++++++++++++++++++++--
security/landlock/syscalls.c | 8 ++++++-
4 files changed, 85 insertions(+), 8 deletions(-)
diff --git a/security/landlock/limits.h b/security/landlock/limits.h
index bafb3b8dc677..8a1a6463c64e 100644
--- a/security/landlock/limits.h
+++ b/security/landlock/limits.h
@@ -23,6 +23,10 @@
#define LANDLOCK_NUM_ACCESS_FS __const_hweight64(LANDLOCK_MASK_ACCESS_FS)
#define LANDLOCK_SHIFT_ACCESS_FS 0
-/* clang-format on */
+#define LANDLOCK_LAST_ACCESS_NET LANDLOCK_ACCESS_NET_CONNECT_TCP
+#define LANDLOCK_MASK_ACCESS_NET ((LANDLOCK_LAST_ACCESS_NET << 1) - 1)
+#define LANDLOCK_NUM_ACCESS_NET __const_hweight64(LANDLOCK_MASK_ACCESS_NET)
+#define LANDLOCK_SHIFT_ACCESS_NET LANDLOCK_NUM_ACCESS_FS
+/* clang-format on */
#endif /* _SECURITY_LANDLOCK_LIMITS_H */
diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
index 84fcd8eb30d4..442f212039df 100644
--- a/security/landlock/ruleset.c
+++ b/security/landlock/ruleset.c
@@ -36,6 +36,7 @@ static struct landlock_ruleset *create_ruleset(const u32 num_layers)
refcount_set(&new_ruleset->usage, 1);
mutex_init(&new_ruleset->lock);
new_ruleset->root_inode = RB_ROOT;
+ new_ruleset->root_net_port = RB_ROOT;
new_ruleset->num_layers = num_layers;
/*
* hierarchy = NULL
@@ -46,16 +47,21 @@ static struct landlock_ruleset *create_ruleset(const u32 num_layers)
}
struct landlock_ruleset *
-landlock_create_ruleset(const access_mask_t fs_access_mask)
+landlock_create_ruleset(const access_mask_t fs_access_mask,
+ const access_mask_t net_access_mask)
{
struct landlock_ruleset *new_ruleset;
/* Informs about useless ruleset. */
- if (!fs_access_mask)
+ if (!fs_access_mask && !net_access_mask)
return ERR_PTR(-ENOMSG);
new_ruleset = create_ruleset(1);
- if (!IS_ERR(new_ruleset))
+ if (IS_ERR(new_ruleset))
+ return new_ruleset;
+ if (fs_access_mask)
landlock_add_fs_access_mask(new_ruleset, fs_access_mask, 0);
+ if (net_access_mask)
+ landlock_add_net_access_mask(new_ruleset, net_access_mask, 0);
return new_ruleset;
}
@@ -73,6 +79,8 @@ static inline bool is_object_pointer(const enum landlock_key_type key_type)
switch (key_type) {
case LANDLOCK_KEY_INODE:
return true;
+ case LANDLOCK_KEY_NET_PORT:
+ return false;
}
WARN_ON_ONCE(1);
return false;
@@ -126,6 +134,9 @@ static inline struct rb_root *get_root(struct landlock_ruleset *const ruleset,
case LANDLOCK_KEY_INODE:
root = &ruleset->root_inode;
break;
+ case LANDLOCK_KEY_NET_PORT:
+ root = &ruleset->root_net_port;
+ break;
}
if (WARN_ON_ONCE(!root))
return ERR_PTR(-EINVAL);
@@ -154,7 +165,9 @@ static void build_check_ruleset(void)
BUILD_BUG_ON(ruleset.num_rules < LANDLOCK_MAX_NUM_RULES);
BUILD_BUG_ON(ruleset.num_layers < LANDLOCK_MAX_NUM_LAYERS);
BUILD_BUG_ON(access_masks <
- (LANDLOCK_MASK_ACCESS_FS << LANDLOCK_SHIFT_ACCESS_FS));
+ (LANDLOCK_MASK_ACCESS_FS << LANDLOCK_SHIFT_ACCESS_FS) +
+ (LANDLOCK_MASK_ACCESS_NET
+ << LANDLOCK_SHIFT_ACCESS_NET));
}
/**
@@ -367,6 +380,11 @@ static int merge_ruleset(struct landlock_ruleset *const dst,
if (err)
goto out_unlock;
+ /* Merges the @src network port tree. */
+ err = merge_tree(dst, src, LANDLOCK_KEY_NET_PORT);
+ if (err)
+ goto out_unlock;
+
out_unlock:
mutex_unlock(&src->lock);
mutex_unlock(&dst->lock);
@@ -419,6 +437,11 @@ static int inherit_ruleset(struct landlock_ruleset *const parent,
if (err)
goto out_unlock;
+ /* Copies the @parent network port tree. */
+ err = inherit_tree(parent, child, LANDLOCK_KEY_NET_PORT);
+ if (err)
+ goto out_unlock;
+
if (WARN_ON_ONCE(child->num_layers <= parent->num_layers)) {
err = -EINVAL;
goto out_unlock;
@@ -451,6 +474,9 @@ static void free_ruleset(struct landlock_ruleset *const ruleset)
rbtree_postorder_for_each_entry_safe(freeme, next, &ruleset->root_inode,
node)
free_rule(freeme, LANDLOCK_KEY_INODE);
+ rbtree_postorder_for_each_entry_safe(freeme, next,
+ &ruleset->root_net_port, node)
+ free_rule(freeme, LANDLOCK_KEY_NET_PORT);
put_hierarchy(ruleset->hierarchy);
kfree(ruleset);
}
@@ -640,6 +666,10 @@ access_mask_t init_layer_masks(const struct landlock_ruleset *const domain,
get_access_mask = landlock_get_fs_access_mask;
num_access = LANDLOCK_NUM_ACCESS_FS;
break;
+ case LANDLOCK_KEY_NET_PORT:
+ get_access_mask = landlock_get_net_access_mask;
+ num_access = LANDLOCK_NUM_ACCESS_NET;
+ break;
default:
WARN_ON_ONCE(1);
return 0;
diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h
index 2083855bf42d..d456ee90b648 100644
--- a/security/landlock/ruleset.h
+++ b/security/landlock/ruleset.h
@@ -26,7 +26,7 @@ static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_FS);
static_assert(sizeof(unsigned long) >= sizeof(access_mask_t));
/* Ruleset access masks. */
-typedef u16 access_masks_t;
+typedef u32 access_masks_t;
/* Makes sure all ruleset access rights can be stored. */
static_assert(BITS_PER_TYPE(access_masks_t) >= LANDLOCK_NUM_ACCESS_FS);
@@ -66,6 +66,11 @@ enum landlock_key_type {
* keys.
*/
LANDLOCK_KEY_INODE = 1,
+ /**
+ * @LANDLOCK_KEY_NET_PORT: Type of &landlock_ruleset.root_net_port's
+ * node keys.
+ */
+ LANDLOCK_KEY_NET_PORT = 2,
};
/**
@@ -133,6 +138,12 @@ struct landlock_ruleset {
* reaches zero.
*/
struct rb_root root_inode;
+ /**
+ * @root_net_port: Root of a red-black tree containing object nodes
+ * for network port. Once a ruleset is tied to a process (i.e. as a domain),
+ * this tree is immutable until @usage reaches zero.
+ */
+ struct rb_root root_net_port;
/**
* @hierarchy: Enables hierarchy identification even when a parent
* domain vanishes. This is needed for the ptrace protection.
@@ -188,7 +199,8 @@ struct landlock_ruleset {
};
struct landlock_ruleset *
-landlock_create_ruleset(const access_mask_t access_mask);
+landlock_create_ruleset(const access_mask_t access_mask_fs,
+ const access_mask_t access_mask_net);
void landlock_put_ruleset(struct landlock_ruleset *const ruleset);
void landlock_put_ruleset_deferred(struct landlock_ruleset *const ruleset);
@@ -226,6 +238,21 @@ landlock_add_fs_access_mask(struct landlock_ruleset *const ruleset,
(fs_mask << LANDLOCK_SHIFT_ACCESS_FS);
}
+/* A helper function to set a network mask. */
+static inline void
+landlock_add_net_access_mask(struct landlock_ruleset *const ruleset,
+ const access_mask_t net_access_mask,
+ const u16 layer_level)
+{
+ access_mask_t net_mask = net_access_mask & LANDLOCK_MASK_ACCESS_NET;
+
+ /* Should already be checked in sys_landlock_create_ruleset(). */
+ WARN_ON_ONCE(net_access_mask != net_mask);
+ // TODO: Add tests to check "|=" and not "="
+ ruleset->access_masks[layer_level] |=
+ (net_mask << LANDLOCK_SHIFT_ACCESS_NET);
+}
+
/* A helper function to get a filesystem mask. */
static inline access_mask_t
landlock_get_fs_access_mask(const struct landlock_ruleset *const ruleset,
@@ -236,6 +263,16 @@ landlock_get_fs_access_mask(const struct landlock_ruleset *const ruleset,
LANDLOCK_MASK_ACCESS_FS;
}
+/* A helper function to get a network mask. */
+static inline access_mask_t
+landlock_get_net_access_mask(const struct landlock_ruleset *const ruleset,
+ const u16 layer_level)
+{
+ return (ruleset->access_masks[layer_level] >>
+ LANDLOCK_SHIFT_ACCESS_NET) &
+ LANDLOCK_MASK_ACCESS_NET;
+}
+
bool unmask_layers(const struct landlock_rule *const rule,
const access_mask_t access_request,
layer_mask_t (*const layer_masks)[],
diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c
index ffd5805eddd9..641155f6f6f8 100644
--- a/security/landlock/syscalls.c
+++ b/security/landlock/syscalls.c
@@ -189,8 +189,14 @@ SYSCALL_DEFINE3(landlock_create_ruleset,
LANDLOCK_MASK_ACCESS_FS)
return -EINVAL;
+ /* Checks network content (and 32-bits cast). */
+ if ((ruleset_attr.handled_access_net | LANDLOCK_MASK_ACCESS_NET) !=
+ LANDLOCK_MASK_ACCESS_NET)
+ return -EINVAL;
+
/* Checks arguments and transforms to kernel struct. */
- ruleset = landlock_create_ruleset(ruleset_attr.handled_access_fs);
+ ruleset = landlock_create_ruleset(ruleset_attr.handled_access_fs,
+ ruleset_attr.handled_access_net);
if (IS_ERR(ruleset))
return PTR_ERR(ruleset);
--
2.25.1
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