diff options
| -rw-r--r-- | include/linux/net.h | 3 | ||||
| -rw-r--r-- | net/socket.c | 46 |
2 files changed, 49 insertions, 0 deletions
diff --git a/include/linux/net.h b/include/linux/net.h index 0620f5e18c96..a42fab24c8af 100644 --- a/include/linux/net.h +++ b/include/linux/net.h @@ -298,6 +298,9 @@ int kernel_sendpage(struct socket *sock, struct page *page, int offset, int kernel_sock_ioctl(struct socket *sock, int cmd, unsigned long arg); int kernel_sock_shutdown(struct socket *sock, enum sock_shutdown_cmd how); +/* Following routine returns the IP overhead imposed by a socket. */ +u32 kernel_sock_ip_overhead(struct sock *sk); + #define MODULE_ALIAS_NETPROTO(proto) \ MODULE_ALIAS("net-pf-" __stringify(proto)) diff --git a/net/socket.c b/net/socket.c index 985ef06792d6..eea997036ada 100644 --- a/net/socket.c +++ b/net/socket.c @@ -3356,3 +3356,49 @@ int kernel_sock_shutdown(struct socket *sock, enum sock_shutdown_cmd how) return sock->ops->shutdown(sock, how); } EXPORT_SYMBOL(kernel_sock_shutdown); + +/* This routine returns the IP overhead imposed by a socket i.e. + * the length of the underlying IP header, depending on whether + * this is an IPv4 or IPv6 socket and the length from IP options turned + * on at the socket. + */ +u32 kernel_sock_ip_overhead(struct sock *sk) +{ + struct inet_sock *inet; + struct ip_options_rcu *opt; + u32 overhead = 0; + bool owned_by_user; +#if IS_ENABLED(CONFIG_IPV6) + struct ipv6_pinfo *np; + struct ipv6_txoptions *optv6 = NULL; +#endif /* IS_ENABLED(CONFIG_IPV6) */ + + if (!sk) + return overhead; + + owned_by_user = sock_owned_by_user(sk); + switch (sk->sk_family) { + case AF_INET: + inet = inet_sk(sk); + overhead += sizeof(struct iphdr); + opt = rcu_dereference_protected(inet->inet_opt, + owned_by_user); + if (opt) + overhead += opt->opt.optlen; + return overhead; +#if IS_ENABLED(CONFIG_IPV6) + case AF_INET6: + np = inet6_sk(sk); + overhead += sizeof(struct ipv6hdr); + if (np) + optv6 = rcu_dereference_protected(np->opt, + owned_by_user); + if (optv6) + overhead += (optv6->opt_flen + optv6->opt_nflen); + return overhead; +#endif /* IS_ENABLED(CONFIG_IPV6) */ + default: /* Returns 0 overhead if the socket is not ipv4 or ipv6 */ + return overhead; + } +} +EXPORT_SYMBOL(kernel_sock_ip_overhead); |