From 113c3075931a334f899008f6c753abe70a3a9323 Mon Sep 17 00:00:00 2001 From: "R. Parameswaran" Date: Wed, 5 Apr 2017 16:50:35 -0700 Subject: New kernel function to get IP overhead on a socket. A new function, kernel_sock_ip_overhead(), is provided to calculate the cumulative overhead imposed by the IP Header and IP options, if any, on a socket's payload. The new function returns an overhead of zero for sockets that do not belong to the IPv4 or IPv6 address families. This is used in the L2TP code path to compute the total outer IP overhead on the L2TP tunnel socket when calculating the default MTU for Ethernet pseudowires. Signed-off-by: R. Parameswaran Signed-off-by: David S. Miller --- net/socket.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) (limited to 'net/socket.c') 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); -- cgit v1.2.3 From 57240d007816486131bee88cd474c2a71f0fe224 Mon Sep 17 00:00:00 2001 From: "R. Parameswaran" Date: Wed, 12 Apr 2017 18:31:04 -0700 Subject: l2tp: device MTU setup, tunnel socket needs a lock The MTU overhead calculation in L2TP device set-up merged via commit b784e7ebfce8cfb16c6f95e14e8532d0768ab7ff needs to be adjusted to lock the tunnel socket while referencing the sub-data structures to derive the socket's IP overhead. Reported-by: Guillaume Nault Tested-by: Guillaume Nault Signed-off-by: R. Parameswaran Signed-off-by: David S. Miller --- include/linux/net.h | 2 +- net/l2tp/l2tp_eth.c | 2 ++ net/socket.c | 2 +- 3 files changed, 4 insertions(+), 2 deletions(-) (limited to 'net/socket.c') diff --git a/include/linux/net.h b/include/linux/net.h index a42fab24c8af..abcfa46a2bd9 100644 --- a/include/linux/net.h +++ b/include/linux/net.h @@ -298,7 +298,7 @@ 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. */ +/* Routine returns the IP overhead imposed by a (caller-protected) socket. */ u32 kernel_sock_ip_overhead(struct sock *sk); #define MODULE_ALIAS_NETPROTO(proto) \ diff --git a/net/l2tp/l2tp_eth.c b/net/l2tp/l2tp_eth.c index 138566a63123..b722d559c544 100644 --- a/net/l2tp/l2tp_eth.c +++ b/net/l2tp/l2tp_eth.c @@ -225,7 +225,9 @@ static void l2tp_eth_adjust_mtu(struct l2tp_tunnel *tunnel, dev->needed_headroom += session->hdr_len; return; } + lock_sock(tunnel->sock); l3_overhead = kernel_sock_ip_overhead(tunnel->sock); + release_sock(tunnel->sock); if (l3_overhead == 0) { /* L3 Overhead couldn't be identified, this could be * because tunnel->sock was NULL or the socket's diff --git a/net/socket.c b/net/socket.c index eea997036ada..c2564eb25c6b 100644 --- a/net/socket.c +++ b/net/socket.c @@ -3360,7 +3360,7 @@ 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. + * on at the socket. Assumes that the caller has a lock on the socket. */ u32 kernel_sock_ip_overhead(struct sock *sk) { -- cgit v1.2.3