1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Pluggable TCP upper layer protocol support. 4 * 5 * Copyright (c) 2016-2017, Mellanox Technologies. All rights reserved. 6 * Copyright (c) 2016-2017, Dave Watson <davejwatson@fb.com>. All rights reserved. 7 * 8 */ 9 10 #include <linux/module.h> 11 #include <linux/mm.h> 12 #include <linux/types.h> 13 #include <linux/list.h> 14 #include <linux/gfp.h> 15 #include <net/tcp.h> 16 17 static DEFINE_SPINLOCK(tcp_ulp_list_lock); 18 static LIST_HEAD(tcp_ulp_list); 19 20 /* Simple linear search, don't expect many entries! */ 21 static struct tcp_ulp_ops *tcp_ulp_find(const char *name) 22 { 23 struct tcp_ulp_ops *e; 24 25 list_for_each_entry_rcu(e, &tcp_ulp_list, list) { 26 if (strcmp(e->name, name) == 0) 27 return e; 28 } 29 30 return NULL; 31 } 32 33 static const struct tcp_ulp_ops *__tcp_ulp_find_autoload(const char *name) 34 { 35 const struct tcp_ulp_ops *ulp = NULL; 36 37 rcu_read_lock(); 38 ulp = tcp_ulp_find(name); 39 40 #ifdef CONFIG_MODULES 41 if (!ulp && capable(CAP_NET_ADMIN)) { 42 rcu_read_unlock(); 43 request_module("tcp-ulp-%s", name); 44 rcu_read_lock(); 45 ulp = tcp_ulp_find(name); 46 } 47 #endif 48 if (!ulp || !try_module_get(ulp->owner)) 49 ulp = NULL; 50 51 rcu_read_unlock(); 52 return ulp; 53 } 54 55 /* Attach new upper layer protocol to the list 56 * of available protocols. 57 */ 58 int tcp_register_ulp(struct tcp_ulp_ops *ulp) 59 { 60 int ret = 0; 61 62 spin_lock(&tcp_ulp_list_lock); 63 if (tcp_ulp_find(ulp->name)) 64 ret = -EEXIST; 65 else 66 list_add_tail_rcu(&ulp->list, &tcp_ulp_list); 67 spin_unlock(&tcp_ulp_list_lock); 68 69 return ret; 70 } 71 EXPORT_SYMBOL_GPL(tcp_register_ulp); 72 73 void tcp_unregister_ulp(struct tcp_ulp_ops *ulp) 74 { 75 spin_lock(&tcp_ulp_list_lock); 76 list_del_rcu(&ulp->list); 77 spin_unlock(&tcp_ulp_list_lock); 78 79 synchronize_rcu(); 80 } 81 EXPORT_SYMBOL_GPL(tcp_unregister_ulp); 82 83 /* Build string with list of available upper layer protocl values */ 84 void tcp_get_available_ulp(char *buf, size_t maxlen) 85 { 86 struct tcp_ulp_ops *ulp_ops; 87 size_t offs = 0; 88 89 *buf = '\0'; 90 rcu_read_lock(); 91 list_for_each_entry_rcu(ulp_ops, &tcp_ulp_list, list) { 92 offs += snprintf(buf + offs, maxlen - offs, 93 "%s%s", 94 offs == 0 ? "" : " ", ulp_ops->name); 95 } 96 rcu_read_unlock(); 97 } 98 99 void tcp_cleanup_ulp(struct sock *sk) 100 { 101 struct inet_connection_sock *icsk = inet_csk(sk); 102 103 /* No sock_owned_by_me() check here as at the time the 104 * stack calls this function, the socket is dead and 105 * about to be destroyed. 106 */ 107 if (!icsk->icsk_ulp_ops) 108 return; 109 110 if (icsk->icsk_ulp_ops->release) 111 icsk->icsk_ulp_ops->release(sk); 112 module_put(icsk->icsk_ulp_ops->owner); 113 114 icsk->icsk_ulp_ops = NULL; 115 } 116 117 static int __tcp_set_ulp(struct sock *sk, const struct tcp_ulp_ops *ulp_ops) 118 { 119 struct inet_connection_sock *icsk = inet_csk(sk); 120 int err; 121 122 err = -EEXIST; 123 if (icsk->icsk_ulp_ops) 124 goto out_err; 125 126 err = ulp_ops->init(sk); 127 if (err) 128 goto out_err; 129 130 icsk->icsk_ulp_ops = ulp_ops; 131 return 0; 132 out_err: 133 module_put(ulp_ops->owner); 134 return err; 135 } 136 137 int tcp_set_ulp(struct sock *sk, const char *name) 138 { 139 const struct tcp_ulp_ops *ulp_ops; 140 141 sock_owned_by_me(sk); 142 143 ulp_ops = __tcp_ulp_find_autoload(name); 144 if (!ulp_ops) 145 return -ENOENT; 146 147 return __tcp_set_ulp(sk, ulp_ops); 148 } 149