9bb59a21f5
snprintf returns the number of chars that would be written, not number of chars that were actually written. As such, 'offs' may get larger than 'tbl.maxlen', causing the 'tbl.maxlen - offs' being < 0, and since the parameter is size_t, it would overflow. Since using scnprintf may hide the limit error, while the buffer is still enough now, let's just add a WARN_ON_ONCE in case it reach the limit in future. v2: Use WARN_ON_ONCE as Jiri and Eric suggested. Suggested-by: Jiri Benc <jbenc@redhat.com> Signed-off-by: Hangbin Liu <liuhangbin@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
165 lines
3.3 KiB
C
165 lines
3.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Pluggable TCP upper layer protocol support.
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*
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* Copyright (c) 2016-2017, Mellanox Technologies. All rights reserved.
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* Copyright (c) 2016-2017, Dave Watson <davejwatson@fb.com>. All rights reserved.
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*
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*/
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#include <linux/module.h>
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#include <linux/mm.h>
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#include <linux/types.h>
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#include <linux/list.h>
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#include <linux/gfp.h>
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#include <net/tcp.h>
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static DEFINE_SPINLOCK(tcp_ulp_list_lock);
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static LIST_HEAD(tcp_ulp_list);
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/* Simple linear search, don't expect many entries! */
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static struct tcp_ulp_ops *tcp_ulp_find(const char *name)
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{
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struct tcp_ulp_ops *e;
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list_for_each_entry_rcu(e, &tcp_ulp_list, list) {
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if (strcmp(e->name, name) == 0)
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return e;
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}
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return NULL;
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}
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static const struct tcp_ulp_ops *__tcp_ulp_find_autoload(const char *name)
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{
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const struct tcp_ulp_ops *ulp = NULL;
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rcu_read_lock();
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ulp = tcp_ulp_find(name);
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#ifdef CONFIG_MODULES
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if (!ulp && capable(CAP_NET_ADMIN)) {
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rcu_read_unlock();
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request_module("tcp-ulp-%s", name);
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rcu_read_lock();
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ulp = tcp_ulp_find(name);
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}
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#endif
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if (!ulp || !try_module_get(ulp->owner))
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ulp = NULL;
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rcu_read_unlock();
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return ulp;
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}
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/* Attach new upper layer protocol to the list
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* of available protocols.
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*/
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int tcp_register_ulp(struct tcp_ulp_ops *ulp)
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{
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int ret = 0;
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spin_lock(&tcp_ulp_list_lock);
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if (tcp_ulp_find(ulp->name))
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ret = -EEXIST;
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else
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list_add_tail_rcu(&ulp->list, &tcp_ulp_list);
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spin_unlock(&tcp_ulp_list_lock);
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return ret;
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}
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EXPORT_SYMBOL_GPL(tcp_register_ulp);
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void tcp_unregister_ulp(struct tcp_ulp_ops *ulp)
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{
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spin_lock(&tcp_ulp_list_lock);
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list_del_rcu(&ulp->list);
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spin_unlock(&tcp_ulp_list_lock);
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synchronize_rcu();
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}
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EXPORT_SYMBOL_GPL(tcp_unregister_ulp);
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/* Build string with list of available upper layer protocl values */
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void tcp_get_available_ulp(char *buf, size_t maxlen)
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{
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struct tcp_ulp_ops *ulp_ops;
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size_t offs = 0;
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*buf = '\0';
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rcu_read_lock();
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list_for_each_entry_rcu(ulp_ops, &tcp_ulp_list, list) {
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offs += snprintf(buf + offs, maxlen - offs,
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"%s%s",
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offs == 0 ? "" : " ", ulp_ops->name);
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if (WARN_ON_ONCE(offs >= maxlen))
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break;
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}
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rcu_read_unlock();
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}
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void tcp_update_ulp(struct sock *sk, struct proto *proto)
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{
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struct inet_connection_sock *icsk = inet_csk(sk);
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if (!icsk->icsk_ulp_ops) {
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sk->sk_prot = proto;
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return;
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}
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if (icsk->icsk_ulp_ops->update)
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icsk->icsk_ulp_ops->update(sk, proto);
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}
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void tcp_cleanup_ulp(struct sock *sk)
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{
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struct inet_connection_sock *icsk = inet_csk(sk);
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/* No sock_owned_by_me() check here as at the time the
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* stack calls this function, the socket is dead and
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* about to be destroyed.
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*/
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if (!icsk->icsk_ulp_ops)
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return;
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if (icsk->icsk_ulp_ops->release)
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icsk->icsk_ulp_ops->release(sk);
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module_put(icsk->icsk_ulp_ops->owner);
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icsk->icsk_ulp_ops = NULL;
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}
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static int __tcp_set_ulp(struct sock *sk, const struct tcp_ulp_ops *ulp_ops)
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{
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struct inet_connection_sock *icsk = inet_csk(sk);
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int err;
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err = -EEXIST;
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if (icsk->icsk_ulp_ops)
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goto out_err;
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err = ulp_ops->init(sk);
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if (err)
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goto out_err;
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icsk->icsk_ulp_ops = ulp_ops;
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return 0;
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out_err:
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module_put(ulp_ops->owner);
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return err;
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}
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int tcp_set_ulp(struct sock *sk, const char *name)
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{
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const struct tcp_ulp_ops *ulp_ops;
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sock_owned_by_me(sk);
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ulp_ops = __tcp_ulp_find_autoload(name);
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if (!ulp_ops)
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return -ENOENT;
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return __tcp_set_ulp(sk, ulp_ops);
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}
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