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mptcp: explicitly specify sock family at subflow creation time

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Let the caller specify the to-be-created subflow family.

For a given MPTCP socket created with the AF_INET6 family, the current
userspace PM can already ask the kernel to create subflows in v4 and v6.
If "plain" IPv4 addresses are passed to the kernel, they are
automatically mapped in v6 addresses "by accident". This can be
problematic because the userspace will need to pass different addresses,
now the v4-mapped-v6 addresses to destroy this new subflow.

On the other hand, if the MPTCP socket has been created with the AF_INET
family, the command to create a subflow in v6 will be accepted but the
result will not be the one as expected as new subflow will be created in
IPv4 using part of the v6 addresses passed to the kernel: not creating
the expected subflow then.

No functional change intended for the in-kernel PM where an explicit
enforcement is currently in place. This arbitrary enforcement will be
leveraged by other patches in a future version.

Fixes: 702c2f646d ("mptcp: netlink: allow userspace-driven subflow establishment")
Cc: stable@vger.kernel.org
Co-developed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Paolo Abeni 2023-01-12 18:42:51 +01:00 committed by Jakub Kicinski
parent 925f3deb45
commit 6bc1fe7dd7
3 changed files with 8 additions and 6 deletions
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2
net/mptcp/protocol.c
View File

@ -98,7 +98,7 @@ static int __mptcp_socket_create(struct mptcp_sock *msk)
struct socket *ssock;
int err;
err = mptcp_subflow_create_socket(sk, &ssock);
err = mptcp_subflow_create_socket(sk, sk->sk_family, &ssock);
if (err)
return err;

3
net/mptcp/protocol.h
View File

@ -641,7 +641,8 @@ bool mptcp_addresses_equal(const struct mptcp_addr_info *a,
/* called with sk socket lock held */
int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_addr_info *loc,
const struct mptcp_addr_info *remote);
int mptcp_subflow_create_socket(struct sock *sk, struct socket **new_sock);
int mptcp_subflow_create_socket(struct sock *sk, unsigned short family,
struct socket **new_sock);
void mptcp_info2sockaddr(const struct mptcp_addr_info *info,
struct sockaddr_storage *addr,
unsigned short family);

9
net/mptcp/subflow.c
View File

@ -1547,7 +1547,7 @@ int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_addr_info *loc,
if (!mptcp_is_fully_established(sk))
goto err_out;
err = mptcp_subflow_create_socket(sk, &sf);
err = mptcp_subflow_create_socket(sk, loc->family, &sf);
if (err)
goto err_out;
@ -1660,7 +1660,9 @@ static void mptcp_subflow_ops_undo_override(struct sock *ssk)
#endif
ssk->sk_prot = &tcp_prot;
}
int mptcp_subflow_create_socket(struct sock *sk, struct socket **new_sock)
int mptcp_subflow_create_socket(struct sock *sk, unsigned short family,
struct socket **new_sock)
{
struct mptcp_subflow_context *subflow;
struct net *net = sock_net(sk);
@ -1673,8 +1675,7 @@ int mptcp_subflow_create_socket(struct sock *sk, struct socket **new_sock)
if (unlikely(!sk->sk_socket))
return -EINVAL;
err = sock_create_kern(net, sk->sk_family, SOCK_STREAM, IPPROTO_TCP,
&sf);
err = sock_create_kern(net, family, SOCK_STREAM, IPPROTO_TCP, &sf);
if (err)
return err;