Unverified Commit e04f97c8 authored by Christian Brauner's avatar Christian Brauner
Browse files

coredump: cleanup coredump socket functions 

We currently use multiple CONFIG_UNIX guards. This looks messy and makes
the code harder to follow and maintain. Use a helper function
coredump_sock_connect() that handles the connect portion. This allows us
to remove the CONFIG_UNIX guard in the main do_coredump() function.

Link: https://lore.kernel.org/20250605-schlamm-touren-720ba2b60a85@brauner


Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent c8e7ce2a

fs/coredump.c

+83 −74
Original line number Diff line number Diff line
@@ -646,6 +646,77 @@ static int umh_coredump_setup(struct subprocess_info *info, struct cred *new) 
}



#ifdef CONFIG_UNIX

static bool coredump_sock_connect(struct core_name *cn, struct coredump_params *cprm)

{

	struct file *file __free(fput) = NULL;

	struct sockaddr_un addr = {

		.sun_family = AF_UNIX,

	};

	ssize_t addr_len;

	int retval;

	struct socket *socket;



	addr_len = strscpy(addr.sun_path, cn->corename);

	if (addr_len < 0)

		return false;

	addr_len += offsetof(struct sockaddr_un, sun_path) + 1;



	/*

	 * It is possible that the userspace process which is supposed

	 * to handle the coredump and is listening on the AF_UNIX socket

	 * coredumps. Userspace should just mark itself non dumpable.

	 */



	retval = sock_create_kern(&init_net, AF_UNIX, SOCK_STREAM, 0, &socket);

	if (retval < 0)

		return false;



	file = sock_alloc_file(socket, 0, NULL);

	if (IS_ERR(file))

		return false;



	/*

	 * Set the thread-group leader pid which is used for the peer

	 * credentials during connect() below. Then immediately register

	 * it in pidfs...

	 */

	cprm->pid = task_tgid(current);

	retval = pidfs_register_pid(cprm->pid);

	if (retval)

		return false;



	/*

	 * ... and set the coredump information so userspace has it

	 * available after connect()...

	 */

	pidfs_coredump(cprm);



	retval = kernel_connect(socket, (struct sockaddr *)(&addr), addr_len,

				O_NONBLOCK | SOCK_COREDUMP);

	/*

	 * ... Make sure to only put our reference after connect() took

	 * its own reference keeping the pidfs entry alive ...

	 */

	pidfs_put_pid(cprm->pid);



	if (retval) {

		if (retval == -EAGAIN)

			coredump_report_failure("Coredump socket %s receive queue full", addr.sun_path);

		else

			coredump_report_failure("Coredump socket connection %s failed %d", addr.sun_path, retval);

		return false;

	}



	/* ... and validate that @sk_peer_pid matches @cprm.pid. */

	if (WARN_ON_ONCE(unix_peer(socket->sk)->sk_peer_pid != cprm->pid))

		return false;



	cprm->limit = RLIM_INFINITY;

	cprm->file = no_free_ptr(file);



	return true;

}



static inline bool coredump_sock_recv(struct file *file, struct coredump_ack *ack, size_t size, int flags)

{

	struct msghdr msg = {};
@@ -707,7 +778,7 @@ static inline void coredump_sock_shutdown(struct file *file) 
	kernel_sock_shutdown(socket, SHUT_WR);

}



static bool coredump_request(struct core_name *cn, struct coredump_params *cprm)

static bool coredump_sock_request(struct core_name *cn, struct coredump_params *cprm)

{

	struct coredump_req req = {

		.size		= sizeof(struct coredump_req),
@@ -770,6 +841,14 @@ static bool coredump_request(struct core_name *cn, struct coredump_params *cprm) 
	return coredump_sock_mark(cprm->file, COREDUMP_MARK_REQACK);

}

#else

static bool coredump_sock_connect(struct core_name *cn,

				  struct coredump_params *cprm)

{

	coredump_report_failure("Core dump socket support %s disabled", cn->corename);

	return false;

}

static bool coredump_sock_request(struct core_name *cn,

				  struct coredump_params *cprm) { return false; }

static inline void coredump_sock_wait(struct file *file) { }

static inline void coredump_sock_shutdown(struct file *file) { }

#endif
@@ -994,83 +1073,13 @@ void do_coredump(const kernel_siginfo_t *siginfo) 
	}

	case COREDUMP_SOCK_REQ:

		fallthrough;

	case COREDUMP_SOCK: {

#ifdef CONFIG_UNIX

		struct file *file __free(fput) = NULL;

		struct sockaddr_un addr = {

			.sun_family = AF_UNIX,

		};

		ssize_t addr_len;

		struct socket *socket;



		addr_len = strscpy(addr.sun_path, cn.corename);

		if (addr_len < 0)

			goto close_fail;

		addr_len += offsetof(struct sockaddr_un, sun_path) + 1;



		/*

		 * It is possible that the userspace process which is

		 * supposed to handle the coredump and is listening on

		 * the AF_UNIX socket coredumps. Userspace should just

		 * mark itself non dumpable.

		 */



		retval = sock_create_kern(&init_net, AF_UNIX, SOCK_STREAM, 0, &socket);

		if (retval < 0)

			goto close_fail;



		file = sock_alloc_file(socket, 0, NULL);

		if (IS_ERR(file))

			goto close_fail;



		/*

		 * Set the thread-group leader pid which is used for the

		 * peer credentials during connect() below. Then

		 * immediately register it in pidfs...

		 */

		cprm.pid = task_tgid(current);

		retval = pidfs_register_pid(cprm.pid);

		if (retval)

			goto close_fail;



		/*

		 * ... and set the coredump information so userspace

		 * has it available after connect()...

		 */

		pidfs_coredump(&cprm);



		retval = kernel_connect(socket, (struct sockaddr *)(&addr),

					addr_len, O_NONBLOCK | SOCK_COREDUMP);



		/*

		 * ... Make sure to only put our reference after connect() took

		 * its own reference keeping the pidfs entry alive ...

		 */

		pidfs_put_pid(cprm.pid);



		if (retval) {

			if (retval == -EAGAIN)

				coredump_report_failure("Coredump socket %s receive queue full", addr.sun_path);

			else

				coredump_report_failure("Coredump socket connection %s failed %d", addr.sun_path, retval);

	case COREDUMP_SOCK:

		if (!coredump_sock_connect(&cn, &cprm))

			goto close_fail;

		}



		/* ... and validate that @sk_peer_pid matches @cprm.pid. */

		if (WARN_ON_ONCE(unix_peer(socket->sk)->sk_peer_pid != cprm.pid))

		if (!coredump_sock_request(&cn, &cprm))

			goto close_fail;



		cprm.limit = RLIM_INFINITY;

		cprm.file = no_free_ptr(file);



		if (!coredump_request(&cn, &cprm))

			goto close_fail;

#else

		coredump_report_failure("Core dump socket support %s disabled", cn.corename);

		goto close_fail;

#endif

		break;

	}

	default:

		WARN_ON_ONCE(true);

		goto close_fail;