From c11c5906bc0aba62a78da69035f6b30c6da6d13b Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Fri, 17 Sep 2021 16:33:21 -0700 Subject: [PATCH] mptcp: add MPTCP_SUBFLOW_ADDRS getsockopt support This retrieves the address pairs of all subflows currently active for a given mptcp connection. It re-uses the same meta-header as for MPTCP_TCPINFO. A new structure is provided to hold the subflow address data: struct mptcp_subflow_addrs { union { __kernel_sa_family_t sa_family; struct sockaddr sa_local; struct sockaddr_in sin_local; struct sockaddr_in6 sin6_local; struct sockaddr_storage ss_local; }; union { struct sockaddr sa_remote; struct sockaddr_in sin_remote; struct sockaddr_in6 sin6_remote; struct sockaddr_storage ss_remote; }; }; Usage of the new getsockopt is very similar to MPTCP_TCPINFO one. Userspace allocates a 'struct mptcp_subflow_data', followed by one or more 'struct mptcp_subflow_addrs', then inits the mptcp_subflow_data structure as follows: struct mptcp_subflow_addrs *sf_addr; struct mptcp_subflow_data *addr; socklen_t olen = sizeof(*addr) + (8 * sizeof(*sf_addr)); addr = malloc(olen); addr->size_subflow_data = sizeof(*addr); addr->num_subflows = 0; addr->size_kernel = 0; addr->size_user = sizeof(struct mptcp_subflow_addrs); sf_addr = (struct mptcp_subflow_addrs *)(addr + 1); and then retrieves the endpoint addresses via: ret = getsockopt(fd, SOL_MPTCP, MPTCP_SUBFLOW_ADDRS, addr, &olen); If the call succeeds, kernel will have added up to 8 endpoint addresses after the 'mptcp_subflow_data' header. Userspace needs to re-check 'olen' value to detect how many bytes have been filled in by the kernel. Userspace can check addr->num_subflows to discover when there were more subflows that available data space. Co-developed-by: Matthieu Baerts Signed-off-by: Matthieu Baerts Signed-off-by: Florian Westphal Signed-off-by: Mat Martineau Signed-off-by: David S. Miller --- include/uapi/linux/mptcp.h | 24 ++++++++++ net/mptcp/sockopt.c | 91 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 115 insertions(+) diff --git a/include/uapi/linux/mptcp.h b/include/uapi/linux/mptcp.h index 3f013a513770..c8cc46f80a16 100644 --- a/include/uapi/linux/mptcp.h +++ b/include/uapi/linux/mptcp.h @@ -4,6 +4,13 @@ #include #include +#include /* for sockaddr_in */ +#include /* for sockaddr_in6 */ +#include /* for sockaddr_storage and sa_family */ + +#ifndef __KERNEL__ +#include /* for struct sockaddr */ +#endif #define MPTCP_SUBFLOW_FLAG_MCAP_REM _BITUL(0) #define MPTCP_SUBFLOW_FLAG_MCAP_LOC _BITUL(1) @@ -200,8 +207,25 @@ struct mptcp_subflow_data { __u32 size_user; /* size of one element in data[] */ } __attribute__((aligned(8))); +struct mptcp_subflow_addrs { + union { + __kernel_sa_family_t sa_family; + struct sockaddr sa_local; + struct sockaddr_in sin_local; + struct sockaddr_in6 sin6_local; + struct __kernel_sockaddr_storage ss_local; + }; + union { + struct sockaddr sa_remote; + struct sockaddr_in sin_remote; + struct sockaddr_in6 sin6_remote; + struct __kernel_sockaddr_storage ss_remote; + }; +}; + /* MPTCP socket options */ #define MPTCP_INFO 1 #define MPTCP_TCPINFO 2 +#define MPTCP_SUBFLOW_ADDRS 3 #endif /* _UAPI_MPTCP_H */ diff --git a/net/mptcp/sockopt.c b/net/mptcp/sockopt.c index eb2905bfa089..8137cc3a4296 100644 --- a/net/mptcp/sockopt.c +++ b/net/mptcp/sockopt.c @@ -840,6 +840,95 @@ static int mptcp_getsockopt_tcpinfo(struct mptcp_sock *msk, char __user *optval, return 0; } +static void mptcp_get_sub_addrs(const struct sock *sk, struct mptcp_subflow_addrs *a) +{ + struct inet_sock *inet = inet_sk(sk); + + memset(a, 0, sizeof(*a)); + + if (sk->sk_family == AF_INET) { + a->sin_local.sin_family = AF_INET; + a->sin_local.sin_port = inet->inet_sport; + a->sin_local.sin_addr.s_addr = inet->inet_rcv_saddr; + + if (!a->sin_local.sin_addr.s_addr) + a->sin_local.sin_addr.s_addr = inet->inet_saddr; + + a->sin_remote.sin_family = AF_INET; + a->sin_remote.sin_port = inet->inet_dport; + a->sin_remote.sin_addr.s_addr = inet->inet_daddr; +#if IS_ENABLED(CONFIG_IPV6) + } else if (sk->sk_family == AF_INET6) { + const struct ipv6_pinfo *np = inet6_sk(sk); + + a->sin6_local.sin6_family = AF_INET6; + a->sin6_local.sin6_port = inet->inet_sport; + + if (ipv6_addr_any(&sk->sk_v6_rcv_saddr)) + a->sin6_local.sin6_addr = np->saddr; + else + a->sin6_local.sin6_addr = sk->sk_v6_rcv_saddr; + + a->sin6_remote.sin6_family = AF_INET6; + a->sin6_remote.sin6_port = inet->inet_dport; + a->sin6_remote.sin6_addr = sk->sk_v6_daddr; +#endif + } +} + +static int mptcp_getsockopt_subflow_addrs(struct mptcp_sock *msk, char __user *optval, + int __user *optlen) +{ + struct sock *sk = &msk->sk.icsk_inet.sk; + struct mptcp_subflow_context *subflow; + unsigned int sfcount = 0, copied = 0; + struct mptcp_subflow_data sfd; + char __user *addrptr; + int len; + + len = mptcp_get_subflow_data(&sfd, optval, optlen); + if (len < 0) + return len; + + sfd.size_kernel = sizeof(struct mptcp_subflow_addrs); + sfd.size_user = min_t(unsigned int, sfd.size_user, + sizeof(struct mptcp_subflow_addrs)); + + addrptr = optval + sfd.size_subflow_data; + + lock_sock(sk); + + mptcp_for_each_subflow(msk, subflow) { + struct sock *ssk = mptcp_subflow_tcp_sock(subflow); + + ++sfcount; + + if (len && len >= sfd.size_user) { + struct mptcp_subflow_addrs a; + + mptcp_get_sub_addrs(ssk, &a); + + if (copy_to_user(addrptr, &a, sfd.size_user)) { + release_sock(sk); + return -EFAULT; + } + + addrptr += sfd.size_user; + copied += sfd.size_user; + len -= sfd.size_user; + } + } + + release_sock(sk); + + sfd.num_subflows = sfcount; + + if (mptcp_put_subflow_data(&sfd, optval, copied, optlen)) + return -EFAULT; + + return 0; +} + static int mptcp_getsockopt_sol_tcp(struct mptcp_sock *msk, int optname, char __user *optval, int __user *optlen) { @@ -862,6 +951,8 @@ static int mptcp_getsockopt_sol_mptcp(struct mptcp_sock *msk, int optname, return mptcp_getsockopt_info(msk, optval, optlen); case MPTCP_TCPINFO: return mptcp_getsockopt_tcpinfo(msk, optval, optlen); + case MPTCP_SUBFLOW_ADDRS: + return mptcp_getsockopt_subflow_addrs(msk, optval, optlen); } return -EOPNOTSUPP;