Merge tag 'landlock-6.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mic/linux

Pull landlock updates from Mickaël Salaün:
 "A Landlock ruleset can now handle two new access rights:
  LANDLOCK_ACCESS_NET_BIND_TCP and LANDLOCK_ACCESS_NET_CONNECT_TCP. When
  handled, the related actions are denied unless explicitly allowed by a
  Landlock network rule for a specific port.

  The related patch series has been reviewed for almost two years, it
  has evolved a lot and we now have reached a decent design, code and
  testing. The refactored kernel code and the new test helpers also
  bring the foundation to support more network protocols.

  Test coverage for security/landlock is 92.4% of 710 lines according to
  gcc/gcov-13, and it was 93.1% of 597 lines before this series. The
  decrease in coverage is due to code refactoring to make the ruleset
  management more generic (i.e. dealing with inodes and ports) that also
  added new WARN_ON_ONCE() checks not possible to test from user space.

  syzkaller has been updated accordingly [4], and such patched instance
  (tailored to Landlock) has been running for a month, covering all the
  new network-related code [5]"

Link: https://lore.kernel.org/r/20231026014751.414649-1-konstantin.meskhidze@huawei.com [1]
Link: https://lore.kernel.org/r/CAHC9VhS1wwgH6NNd+cJz4MYogPiRV8NyPDd1yj5SpaxeUB4UVg@mail.gmail.com [2]
Link: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next-history.git/commit/?id=c8dc5ee69d3a [3]
Link: https://github.com/google/syzkaller/pull/4266 [4]
Link: https://storage.googleapis.com/syzbot-assets/82e8608dec36/ci-upstream-linux-next-kasan-gce-root-ab577164.html#security%2flandlock%2fnet.c [5]

* tag 'landlock-6.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mic/linux:
  selftests/landlock: Add tests for FS topology changes with network rules
  landlock: Document network support
  samples/landlock: Support TCP restrictions
  selftests/landlock: Add network tests
  selftests/landlock: Share enforce_ruleset() helper
  landlock: Support network rules with TCP bind and connect
  landlock: Refactor landlock_add_rule() syscall
  landlock: Refactor layer helpers
  landlock: Move and rename layer helpers
  landlock: Refactor merge/inherit_ruleset helpers
  landlock: Refactor landlock_find_rule/insert_rule helpers
  landlock: Allow FS topology changes for domains without such rule type
  landlock: Make ruleset's access masks more generic

include/uapi/linux/landlock.h

@@ -31,6 +31,12 @@ struct landlock_ruleset_attr {
 	 * this access right.
 	 */
 	__u64 handled_access_fs;
+	/**
+	 * @handled_access_net: Bitmask of actions (cf. `Network flags`_)
+	 * that is handled by this ruleset and should then be forbidden if no
+	 * rule explicitly allow them.
+	 */
+	__u64 handled_access_net;
 };
 
 /*
@@ -54,6 +60,11 @@ enum landlock_rule_type {
 	 * landlock_path_beneath_attr .
 	 */
 	LANDLOCK_RULE_PATH_BENEATH = 1,
+	/**
+	 * @LANDLOCK_RULE_NET_PORT: Type of a &struct
+	 * landlock_net_port_attr .
+	 */
+	LANDLOCK_RULE_NET_PORT,
 };
 
 /**
@@ -79,6 +90,31 @@ struct landlock_path_beneath_attr {
 	 */
 } __attribute__((packed));
 
+/**
+ * struct landlock_net_port_attr - Network port definition
+ *
+ * Argument of sys_landlock_add_rule().
+ */
+struct landlock_net_port_attr {
+	/**
+	 * @allowed_access: Bitmask of allowed access network for a port
+	 * (cf. `Network flags`_).
+	 */
+	__u64 allowed_access;
+	/**
+	 * @port: Network port in host endianness.
+	 *
+	 * It should be noted that port 0 passed to :manpage:`bind(2)` will
+	 * bind to an available port from a specific port range. This can be
+	 * configured thanks to the ``/proc/sys/net/ipv4/ip_local_port_range``
+	 * sysctl (also used for IPv6). A Landlock rule with port 0 and the
+	 * ``LANDLOCK_ACCESS_NET_BIND_TCP`` right means that requesting to bind
+	 * on port 0 is allowed and it will automatically translate to binding
+	 * on the related port range.
+	 */
+	__u64 port;
+};
+
 /**
  * DOC: fs_access
  *
@@ -189,4 +225,23 @@ struct landlock_path_beneath_attr {
 #define LANDLOCK_ACCESS_FS_TRUNCATE			(1ULL << 14)
 /* clang-format on */
 
+/**
+ * DOC: net_access
+ *
+ * Network flags
+ * ~~~~~~~~~~~~~~~~
+ *
+ * These flags enable to restrict a sandboxed process to a set of network
+ * actions. This is supported since the Landlock ABI version 4.
+ *
+ * TCP sockets with allowed actions:
+ *
+ * - %LANDLOCK_ACCESS_NET_BIND_TCP: Bind a TCP socket to a local port.
+ * - %LANDLOCK_ACCESS_NET_CONNECT_TCP: Connect an active TCP socket to
+ *   a remote port.
+ */
+/* clang-format off */
+#define LANDLOCK_ACCESS_NET_BIND_TCP			(1ULL << 0)
+#define LANDLOCK_ACCESS_NET_CONNECT_TCP			(1ULL << 1)
+/* clang-format on */
 #endif /* _UAPI_LINUX_LANDLOCK_H */