// SPDX-License-Identifier: GPL-2.0/* * Copyright (c) 2018 Facebook */#include <linux/bpf.h>#include <linux/err.h>#include <linux/sock_diag.h>#include <net/sock_reuseport.h> struct reuseport_array {	struct bpf_map map;	struct sock __rcu *ptrs[];}; static struct reuseport_array *reuseport_array(struct bpf_map *map){	return (struct reuseport_array *)map;} /* The caller must hold the reuseport_lock */void bpf_sk_reuseport_detach(struct sock *sk){	struct sock __rcu **socks; 	write_lock_bh(&sk->sk_callback_lock);	socks = sk->sk_user_data;	if (socks) {		WRITE_ONCE(sk->sk_user_data, NULL);		/*		 * Do not move this NULL assignment outside of		 * sk->sk_callback_lock because there is		 * a race with reuseport_array_free()		 * which does not hold the reuseport_lock.		 */		RCU_INIT_POINTER(*socks, NULL);	}	write_unlock_bh(&sk->sk_callback_lock);} static int reuseport_array_alloc_check(union bpf_attr *attr){	if (attr->value_size != sizeof(u32) &&	    attr->value_size != sizeof(u64))		return -EINVAL; 	return array_map_alloc_check(attr);} static void *reuseport_array_lookup_elem(struct bpf_map *map, void *key){	struct reuseport_array *array = reuseport_array(map);	u32 index = *(u32 *)key; 	if (unlikely(index >= array->map.max_entries))		return NULL; 	return rcu_dereference(array->ptrs[index]);} /* Called from syscall only */static int reuseport_array_delete_elem(struct bpf_map *map, void *key){	struct reuseport_array *array = reuseport_array(map);	u32 index = *(u32 *)key;	struct sock *sk;	int err; 	if (index >= map->max_entries)		return -E2BIG; 	if (!rcu_access_pointer(array->ptrs[index]))		return -ENOENT; 	spin_lock_bh(&reuseport_lock); 	sk = rcu_dereference_protected(array->ptrs[index],				       lockdep_is_held(&reuseport_lock));	if (sk) {		write_lock_bh(&sk->sk_callback_lock);		WRITE_ONCE(sk->sk_user_data, NULL);		RCU_INIT_POINTER(array->ptrs[index], NULL);		write_unlock_bh(&sk->sk_callback_lock);		err = 0;	} else {		err = -ENOENT;	} 	spin_unlock_bh(&reuseport_lock); 	return err;} static void reuseport_array_free(struct bpf_map *map){	struct reuseport_array *array = reuseport_array(map);	struct sock *sk;	u32 i; 	synchronize_rcu(); 	/*	 * ops->map_*_elem() will not be able to access this	 * array now. Hence, this function only races with	 * bpf_sk_reuseport_detach() which was triggerred by	 * close() or disconnect().	 *	 * This function and bpf_sk_reuseport_detach() are	 * both removing sk from "array".  Who removes it	 * first does not matter.	 *	 * The only concern here is bpf_sk_reuseport_detach()	 * may access "array" which is being freed here.	 * bpf_sk_reuseport_detach() access this "array"	 * through sk->sk_user_data _and_ with sk->sk_callback_lock	 * held which is enough because this "array" is not freed	 * until all sk->sk_user_data has stopped referencing this "array".	 *	 * Hence, due to the above, taking "reuseport_lock" is not	 * needed here.	 */ 	/*	 * Since reuseport_lock is not taken, sk is accessed under	 * rcu_read_lock()	 */	rcu_read_lock();	for (i = 0; i < map->max_entries; i++) {		sk = rcu_dereference(array->ptrs[i]);		if (sk) {			write_lock_bh(&sk->sk_callback_lock);			/*			 * No need for WRITE_ONCE(). At this point,			 * no one is reading it without taking the			 * sk->sk_callback_lock.			 */			sk->sk_user_data = NULL;			write_unlock_bh(&sk->sk_callback_lock);			RCU_INIT_POINTER(array->ptrs[i], NULL);		}	}	rcu_read_unlock(); 	/*	 * Once reaching here, all sk->sk_user_data is not	 * referenceing this "array".  "array" can be freed now.	 */	bpf_map_area_free(array);} static struct bpf_map *reuseport_array_alloc(union bpf_attr *attr){	int err, numa_node = bpf_map_attr_numa_node(attr);	struct reuseport_array *array;	u64 cost, array_size; 	if (!capable(CAP_SYS_ADMIN))		return ERR_PTR(-EPERM); 	array_size = sizeof(*array);	array_size += (u64)attr->max_entries * sizeof(struct sock *); 	/* make sure there is no u32 overflow later in round_up() */	cost = array_size;	if (cost >= U32_MAX - PAGE_SIZE)		return ERR_PTR(-ENOMEM);	cost = round_up(cost, PAGE_SIZE) >> PAGE_SHIFT; 	err = bpf_map_precharge_memlock(cost);	if (err)		return ERR_PTR(err); 	/* allocate all map elements and zero-initialize them */	array = bpf_map_area_alloc(array_size, numa_node);	if (!array)		return ERR_PTR(-ENOMEM); 	/* copy mandatory map attributes */	bpf_map_init_from_attr(&array->map, attr);	array->map.pages = cost; 	return &array->map;} int bpf_fd_reuseport_array_lookup_elem(struct bpf_map *map, void *key,				       void *value){	struct sock *sk;	int err; 	if (map->value_size != sizeof(u64))		return -ENOSPC; 	rcu_read_lock();	sk = reuseport_array_lookup_elem(map, key);	if (sk) {		*(u64 *)value = sock_gen_cookie(sk);		err = 0;	} else {		err = -ENOENT;	}	rcu_read_unlock(); 	return err;} static intreuseport_array_update_check(const struct reuseport_array *array,			     const struct sock *nsk,			     const struct sock *osk,			     const struct sock_reuseport *nsk_reuse,			     u32 map_flags){	if (osk && map_flags == BPF_NOEXIST)		return -EEXIST; 	if (!osk && map_flags == BPF_EXIST)		return -ENOENT; 	if (nsk->sk_protocol != IPPROTO_UDP && nsk->sk_protocol != IPPROTO_TCP)		return -ENOTSUPP; 	if (nsk->sk_family != AF_INET && nsk->sk_family != AF_INET6)		return -ENOTSUPP; 	if (nsk->sk_type != SOCK_STREAM && nsk->sk_type != SOCK_DGRAM)		return -ENOTSUPP; 	/*	 * sk must be hashed (i.e. listening in the TCP case or binded	 * in the UDP case) and	 * it must also be a SO_REUSEPORT sk (i.e. reuse cannot be NULL).	 *	 * Also, sk will be used in bpf helper that is protected by	 * rcu_read_lock().	 */	if (!sock_flag(nsk, SOCK_RCU_FREE) || !sk_hashed(nsk) || !nsk_reuse)		return -EINVAL; 	/* READ_ONCE because the sk->sk_callback_lock may not be held here */	if (READ_ONCE(nsk->sk_user_data))		return -EBUSY; 	return 0;} /* * Called from syscall only. * The "nsk" in the fd refcnt. * The "osk" and "reuse" are protected by reuseport_lock. */int bpf_fd_reuseport_array_update_elem(struct bpf_map *map, void *key,				       void *value, u64 map_flags){	struct reuseport_array *array = reuseport_array(map);	struct sock *free_osk = NULL, *osk, *nsk;	struct sock_reuseport *reuse;	u32 index = *(u32 *)key;	struct socket *socket;	int err, fd; 	if (map_flags > BPF_EXIST)		return -EINVAL; 	if (index >= map->max_entries)		return -E2BIG; 	if (map->value_size == sizeof(u64)) {		u64 fd64 = *(u64 *)value; 		if (fd64 > S32_MAX)			return -EINVAL;		fd = fd64;	} else {		fd = *(int *)value;	} 	socket = sockfd_lookup(fd, &err);	if (!socket)		return err; 	nsk = socket->sk;	if (!nsk) {		err = -EINVAL;		goto put_file;	} 	/* Quick checks before taking reuseport_lock */	err = reuseport_array_update_check(array, nsk,					   rcu_access_pointer(array->ptrs[index]),					   rcu_access_pointer(nsk->sk_reuseport_cb),					   map_flags);	if (err)		goto put_file; 	spin_lock_bh(&reuseport_lock);	/*	 * Some of the checks only need reuseport_lock	 * but it is done under sk_callback_lock also	 * for simplicity reason.	 */	write_lock_bh(&nsk->sk_callback_lock); 	osk = rcu_dereference_protected(array->ptrs[index],					lockdep_is_held(&reuseport_lock));	reuse = rcu_dereference_protected(nsk->sk_reuseport_cb,					  lockdep_is_held(&reuseport_lock));	err = reuseport_array_update_check(array, nsk, osk, reuse, map_flags);	if (err)		goto put_file_unlock; 	/* Ensure reuse->reuseport_id is set */	err = reuseport_get_id(reuse);	if (err < 0)		goto put_file_unlock; 	WRITE_ONCE(nsk->sk_user_data, &array->ptrs[index]);	rcu_assign_pointer(array->ptrs[index], nsk);	free_osk = osk;	err = 0; put_file_unlock:	write_unlock_bh(&nsk->sk_callback_lock); 	if (free_osk) {		write_lock_bh(&free_osk->sk_callback_lock);		WRITE_ONCE(free_osk->sk_user_data, NULL);		write_unlock_bh(&free_osk->sk_callback_lock);	} 	spin_unlock_bh(&reuseport_lock);put_file:	fput(socket->file);	return err;} /* Called from syscall */static int reuseport_array_get_next_key(struct bpf_map *map, void *key,					void *next_key){	struct reuseport_array *array = reuseport_array(map);	u32 index = key ? *(u32 *)key : U32_MAX;	u32 *next = (u32 *)next_key; 	if (index >= array->map.max_entries) {		*next = 0;		return 0;	} 	if (index == array->map.max_entries - 1)		return -ENOENT; 	*next = index + 1;	return 0;} const struct bpf_map_ops reuseport_array_ops = {	.map_alloc_check = reuseport_array_alloc_check,	.map_alloc = reuseport_array_alloc,	.map_free = reuseport_array_free,	.map_lookup_elem = reuseport_array_lookup_elem,	.map_get_next_key = reuseport_array_get_next_key,	.map_delete_elem = reuseport_array_delete_elem,};