Merge tag 'landlock-6.19-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/mic/linux

Pull landlock fixes from Mickaël Salaün:
 "This fixes TCP handling, tests, documentation, non-audit elided code,
  and minor cosmetic changes"

* tag 'landlock-6.19-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/mic/linux:
  landlock: Clarify documentation for the IOCTL access right
  selftests/landlock: Properly close a file descriptor
  landlock: Improve the comment for domain_is_scoped
  selftests/landlock: Use scoped_base_variants.h for ptrace_test
  selftests/landlock: Fix missing semicolon
  selftests/landlock: Fix typo in fs_test
  landlock: Optimize stack usage when !CONFIG_AUDIT
  landlock: Fix spelling
  landlock: Clean up hook_ptrace_access_check()
  landlock: Improve erratum documentation
  landlock: Remove useless include
  landlock: Fix wrong type usage
  selftests/landlock: NULL-terminate unix pathname addresses
  selftests/landlock: Remove invalid unix socket bind()
  selftests/landlock: Add missing connect(minimal AF_UNSPEC) test
  selftests/landlock: Fix TCP bind(AF_UNSPEC) test case
  landlock: Fix TCP handling of short AF_UNSPEC addresses
  landlock: Fix formatting

security/landlock/audit.c

@@ -191,7 +191,7 @@ static size_t get_denied_layer(const struct landlock_ruleset *const domain,
 	long youngest_layer = -1;
 
 	for_each_set_bit(access_bit, &access_req, layer_masks_size) {
-		const access_mask_t mask = (*layer_masks)[access_bit];
+		const layer_mask_t mask = (*layer_masks)[access_bit];
 		long layer;
 
 		if (!mask)

security/landlock/domain.h

@@ -97,7 +97,7 @@ struct landlock_hierarchy {
 	 */
 	atomic64_t num_denials;
 	/**
-	 * @id: Landlock domain ID, sets once at domain creation time.
+	 * @id: Landlock domain ID, set once at domain creation time.
 	 */
 	u64 id;
 	/**

security/landlock/errata/abi-6.h

@@ -9,7 +9,7 @@
  * This fix addresses an issue where signal scoping was overly restrictive,
  * preventing sandboxed threads from signaling other threads within the same
  * process if they belonged to different domains.  Because threads are not
- * security boundaries, user space might assume that any thread within the same
+ * security boundaries, user space might assume that all threads within the same
  * process can send signals between themselves (see :manpage:`nptl(7)` and
  * :manpage:`libpsx(3)`).  Consistent with :manpage:`ptrace(2)` behavior, direct
  * interaction between threads of the same process should always be allowed.

security/landlock/fs.c

@@ -939,7 +939,12 @@ jump_up:
 	}
 	path_put(&walker_path);
 
-	if (!allowed_parent1) {
+	/*
+	 * Check CONFIG_AUDIT to enable elision of log_request_parent* and
+	 * associated caller's stack variables thanks to dead code elimination.
+	 */
+#ifdef CONFIG_AUDIT
+	if (!allowed_parent1 && log_request_parent1) {
 		log_request_parent1->type = LANDLOCK_REQUEST_FS_ACCESS;
 		log_request_parent1->audit.type = LSM_AUDIT_DATA_PATH;
 		log_request_parent1->audit.u.path = *path;
@@ -949,7 +954,7 @@ jump_up:
 			ARRAY_SIZE(*layer_masks_parent1);
 	}
 
-	if (!allowed_parent2) {
+	if (!allowed_parent2 && log_request_parent2) {
 		log_request_parent2->type = LANDLOCK_REQUEST_FS_ACCESS;
 		log_request_parent2->audit.type = LSM_AUDIT_DATA_PATH;
 		log_request_parent2->audit.u.path = *path;
@@ -958,6 +963,8 @@ jump_up:
 		log_request_parent2->layer_masks_size =
 			ARRAY_SIZE(*layer_masks_parent2);
 	}
+#endif /* CONFIG_AUDIT */
+
 	return allowed_parent1 && allowed_parent2;
 }
 
@@ -1314,7 +1321,8 @@ static void hook_sb_delete(struct super_block *const sb)
 		 * second call to iput() for the same Landlock object.  Also
 		 * checks I_NEW because such inode cannot be tied to an object.
 		 */
-		if (inode_state_read(inode) & (I_FREEING | I_WILL_FREE | I_NEW)) {
+		if (inode_state_read(inode) &
+		    (I_FREEING | I_WILL_FREE | I_NEW)) {
 			spin_unlock(&inode->i_lock);
 			continue;
 		}

security/landlock/net.c

@@ -71,6 +71,61 @@ static int current_check_access_socket(struct socket *const sock,
 
 	switch (address->sa_family) {
 	case AF_UNSPEC:
+		if (access_request == LANDLOCK_ACCESS_NET_CONNECT_TCP) {
+			/*
+			 * Connecting to an address with AF_UNSPEC dissolves
+			 * the TCP association, which have the same effect as
+			 * closing the connection while retaining the socket
+			 * object (i.e., the file descriptor).  As for dropping
+			 * privileges, closing connections is always allowed.
+			 *
+			 * For a TCP access control system, this request is
+			 * legitimate. Let the network stack handle potential
+			 * inconsistencies and return -EINVAL if needed.
+			 */
+			return 0;
+		} else if (access_request == LANDLOCK_ACCESS_NET_BIND_TCP) {
+			/*
+			 * Binding to an AF_UNSPEC address is treated
+			 * differently by IPv4 and IPv6 sockets. The socket's
+			 * family may change under our feet due to
+			 * setsockopt(IPV6_ADDRFORM), but that's ok: we either
+			 * reject entirely or require
+			 * %LANDLOCK_ACCESS_NET_BIND_TCP for the given port, so
+			 * it cannot be used to bypass the policy.
+			 *
+			 * IPv4 sockets map AF_UNSPEC to AF_INET for
+			 * retrocompatibility for bind accesses, only if the
+			 * address is INADDR_ANY (cf. __inet_bind). IPv6
+			 * sockets always reject it.
+			 *
+			 * Checking the address is required to not wrongfully
+			 * return -EACCES instead of -EAFNOSUPPORT or -EINVAL.
+			 * We could return 0 and let the network stack handle
+			 * these checks, but it is safer to return a proper
+			 * error and test consistency thanks to kselftest.
+			 */
+			if (sock->sk->__sk_common.skc_family == AF_INET) {
+				const struct sockaddr_in *const sockaddr =
+					(struct sockaddr_in *)address;
+
+				if (addrlen < sizeof(struct sockaddr_in))
+					return -EINVAL;
+
+				if (sockaddr->sin_addr.s_addr !=
+				    htonl(INADDR_ANY))
+					return -EAFNOSUPPORT;
+			} else {
+				if (addrlen < SIN6_LEN_RFC2133)
+					return -EINVAL;
+				else
+					return -EAFNOSUPPORT;
+			}
+		} else {
+			WARN_ON_ONCE(1);
+		}
+		/* Only for bind(AF_UNSPEC+INADDR_ANY) on IPv4 socket. */
+		fallthrough;
 	case AF_INET: {
 		const struct sockaddr_in *addr4;
 
@@ -119,57 +174,18 @@ static int current_check_access_socket(struct socket *const sock,
 		return 0;
 	}
 
-	/* Specific AF_UNSPEC handling. */
-	if (address->sa_family == AF_UNSPEC) {
-		/*
-		 * Connecting to an address with AF_UNSPEC dissolves the TCP
-		 * association, which have the same effect as closing the
-		 * connection while retaining the socket object (i.e., the file
-		 * descriptor).  As for dropping privileges, closing
-		 * connections is always allowed.
-		 *
-		 * For a TCP access control system, this request is legitimate.
-		 * Let the network stack handle potential inconsistencies and
-		 * return -EINVAL if needed.
-		 */
-		if (access_request == LANDLOCK_ACCESS_NET_CONNECT_TCP)
-			return 0;
-
-		/*
-		 * For compatibility reason, accept AF_UNSPEC for bind
-		 * accesses (mapped to AF_INET) only if the address is
-		 * INADDR_ANY (cf. __inet_bind).  Checking the address is
-		 * required to not wrongfully return -EACCES instead of
-		 * -EAFNOSUPPORT.
-		 *
-		 * We could return 0 and let the network stack handle these
-		 * checks, but it is safer to return a proper error and test
-		 * consistency thanks to kselftest.
-		 */
-		if (access_request == LANDLOCK_ACCESS_NET_BIND_TCP) {
-			/* addrlen has already been checked for AF_UNSPEC. */
-			const struct sockaddr_in *const sockaddr =
-				(struct sockaddr_in *)address;
-
-			if (sock->sk->__sk_common.skc_family != AF_INET)
-				return -EINVAL;
-
-			if (sockaddr->sin_addr.s_addr != htonl(INADDR_ANY))
-				return -EAFNOSUPPORT;
-		}
-	} else {
-		/*
-		 * Checks sa_family consistency to not wrongfully return
-		 * -EACCES instead of -EINVAL.  Valid sa_family changes are
-		 * only (from AF_INET or AF_INET6) to AF_UNSPEC.
-		 *
-		 * We could return 0 and let the network stack handle this
-		 * check, but it is safer to return a proper error and test
-		 * consistency thanks to kselftest.
-		 */
-		if (address->sa_family != sock->sk->__sk_common.skc_family)
-			return -EINVAL;
-	}
+	/*
+	 * Checks sa_family consistency to not wrongfully return
+	 * -EACCES instead of -EINVAL.  Valid sa_family changes are
+	 * only (from AF_INET or AF_INET6) to AF_UNSPEC.
+	 *
+	 * We could return 0 and let the network stack handle this
+	 * check, but it is safer to return a proper error and test
+	 * consistency thanks to kselftest.
+	 */
+	if (address->sa_family != sock->sk->__sk_common.skc_family &&
+	    address->sa_family != AF_UNSPEC)
+		return -EINVAL;
 
 	id.key.data = (__force uintptr_t)port;
 	BUILD_BUG_ON(sizeof(port) > sizeof(id.key.data));

security/landlock/ruleset.c

@@ -23,7 +23,6 @@
 #include <linux/workqueue.h>
 
 #include "access.h"
-#include "audit.h"
 #include "domain.h"
 #include "limits.h"
 #include "object.h"

security/landlock/task.c

@@ -86,7 +86,6 @@ static int hook_ptrace_access_check(struct task_struct *const child,
 				    const unsigned int mode)
 {
 	const struct landlock_cred_security *parent_subject;
-	const struct landlock_ruleset *child_dom;
 	int err;
 
 	/* Quick return for non-landlocked tasks. */
@@ -96,7 +95,8 @@ static int hook_ptrace_access_check(struct task_struct *const child,
 
 	scoped_guard(rcu)
 	{
-		child_dom = landlock_get_task_domain(child);
+		const struct landlock_ruleset *const child_dom =
+			landlock_get_task_domain(child);
 		err = domain_ptrace(parent_subject->domain, child_dom);
 	}
 
@@ -166,15 +166,15 @@ static int hook_ptrace_traceme(struct task_struct *const parent)
 }
 
 /**
- * domain_is_scoped - Checks if the client domain is scoped in the same
- *		      domain as the server.
+ * domain_is_scoped - Check if an interaction from a client/sender to a
+ *		      server/receiver should be restricted based on scope controls.
  *
  * @client: IPC sender domain.
  * @server: IPC receiver domain.
  * @scope: The scope restriction criteria.
  *
- * Returns: True if the @client domain is scoped to access the @server,
- * unless the @server is also scoped in the same domain as @client.
+ * Returns: True if @server is in a different domain from @client, and @client
+ * is scoped to access @server (i.e. access should be denied).
  */
 static bool domain_is_scoped(const struct landlock_ruleset *const client,
 			     const struct landlock_ruleset *const server,