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Merge branch 'mptcp-add-REUSEADDR-REUSEPORT-V6ONLY-setsockopt-support'

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Florian Westphal says:

====================
mptcp: add REUSEADDR/REUSEPORT/V6ONLY setsockopt support

restarting an mptcp-patched sshd yields following error:

  sshd: error: Bind to port 22 on 0.0.0.0 failed: Address already in use.
  sshd: error: setsockopt IPV6_V6ONLY: Operation not supported
  sshd: error: Bind to port 22 on :: failed: Address already in use.
  sshd: fatal: Cannot bind any address.

This series adds support for the needed setsockopts:

First patch skips the generic SOL_SOCKET handler for MPTCP:
in mptcp case, the setsockopt needs to alter the tcp socket, not the mptcp
parent socket.

Second patch adds minimal SOL_SOCKET support: REUSEPORT and REUSEADDR.
Rest is still handled by the generic SOL_SOCKET code.

Last patch adds IPV6ONLY support.  This makes ipv6 work for openssh:
It creates two listening sockets, before this patch, binding the ipv6
socket will fail because the port is already bound by the ipv4 one.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2020-07-04 17:56:22 -07:00
commit bdd2ed2721
2 changed files with 76 additions and 1 deletions
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64
net/mptcp/protocol.c
View File

@ -1601,6 +1601,64 @@ static void mptcp_destroy(struct sock *sk)
sk_sockets_allocated_dec(sk);
}
static int mptcp_setsockopt_sol_socket(struct mptcp_sock *msk, int optname,
char __user *optval, unsigned int optlen)
{
struct sock *sk = (struct sock *)msk;
struct socket *ssock;
int ret;
switch (optname) {
case SO_REUSEPORT:
case SO_REUSEADDR:
lock_sock(sk);
ssock = __mptcp_nmpc_socket(msk);
if (!ssock) {
release_sock(sk);
return -EINVAL;
}
ret = sock_setsockopt(ssock, SOL_SOCKET, optname, optval, optlen);
if (ret == 0) {
if (optname == SO_REUSEPORT)
sk->sk_reuseport = ssock->sk->sk_reuseport;
else if (optname == SO_REUSEADDR)
sk->sk_reuse = ssock->sk->sk_reuse;
}
release_sock(sk);
return ret;
}
return sock_setsockopt(sk->sk_socket, SOL_SOCKET, optname, optval, optlen);
}
static int mptcp_setsockopt_v6(struct mptcp_sock *msk, int optname,
char __user *optval, unsigned int optlen)
{
struct sock *sk = (struct sock *)msk;
int ret = -EOPNOTSUPP;
struct socket *ssock;
switch (optname) {
case IPV6_V6ONLY:
lock_sock(sk);
ssock = __mptcp_nmpc_socket(msk);
if (!ssock) {
release_sock(sk);
return -EINVAL;
}
ret = tcp_setsockopt(ssock->sk, SOL_IPV6, optname, optval, optlen);
if (ret == 0)
sk->sk_ipv6only = ssock->sk->sk_ipv6only;
release_sock(sk);
break;
}
return ret;
}
static int mptcp_setsockopt(struct sock *sk, int level, int optname,
char __user *optval, unsigned int optlen)
{
@ -1609,6 +1667,9 @@ static int mptcp_setsockopt(struct sock *sk, int level, int optname,
pr_debug("msk=%p", msk);
if (level == SOL_SOCKET)
return mptcp_setsockopt_sol_socket(msk, optname, optval, optlen);
/* @@ the meaning of setsockopt() when the socket is connected and
* there are multiple subflows is not yet defined. It is up to the
* MPTCP-level socket to configure the subflows until the subflow
@ -1621,6 +1682,9 @@ static int mptcp_setsockopt(struct sock *sk, int level, int optname,
if (ssk)
return tcp_setsockopt(ssk, level, optname, optval, optlen);
if (level == SOL_IPV6)
return mptcp_setsockopt_v6(msk, optname, optval, optlen);
return -EOPNOTSUPP;
}

13
net/socket.c
View File

@ -2080,6 +2080,17 @@ SYSCALL_DEFINE4(recv, int, fd, void __user *, ubuf, size_t, size,
return __sys_recvfrom(fd, ubuf, size, flags, NULL, NULL);
}
static bool sock_use_custom_sol_socket(const struct socket *sock)
{
const struct sock *sk = sock->sk;
/* Use sock->ops->setsockopt() for MPTCP */
return IS_ENABLED(CONFIG_MPTCP) &&
sk->sk_protocol == IPPROTO_MPTCP &&
sk->sk_type == SOCK_STREAM &&
(sk->sk_family == AF_INET || sk->sk_family == AF_INET6);
}
/*
* Set a socket option. Because we don't know the option lengths we have
* to pass the user mode parameter for the protocols to sort out.
@ -2118,7 +2129,7 @@ static int __sys_setsockopt(int fd, int level, int optname,
optval = (char __user __force *)kernel_optval;
}
if (level == SOL_SOCKET)
if (level == SOL_SOCKET && !sock_use_custom_sol_socket(sock))
err =
sock_setsockopt(sock, level, optname, optval,
optlen);