In order to support TCP_REPAIR for connections using RFC5925 Authentication Option add a sockopt to get/set ISN and SNE values.
The TCP_REPAIR_AUTHOxpTP sockopt is only allowed when the socket is already in "repair" mode, this behavior is shared with other sockopts relevant to TCP_REPAIR.
The setsockopt further requires the TCP_ESTABLISHED state, this is because it relies on snd_nxt which is only initialized after connect().
For SNE restoration we provide a full 64-bit sequence number on "get" and handle any recent 64-bit sequence number on "set", where recent means "within ~2GB to the current window".
Linux tracks snd_sne and rcv_sne as the extension of snd_nxt and rcv_nxt but this is an implementation detail and snd_nxt doesn't even seem to be one of the values that can be read by userspace. Handling SNE with 64-bit values means userspace doesn't need to worry about matching snd_nxt.
Signed-off-by: Leonard Crestez cdleonard@gmail.com --- include/net/tcp_authopt.h | 2 ++ include/uapi/linux/tcp.h | 19 +++++++++++ net/ipv4/tcp.c | 23 ++++++++++++++ net/ipv4/tcp_authopt.c | 66 +++++++++++++++++++++++++++++++++++++++ 4 files changed, 110 insertions(+)
diff --git a/include/net/tcp_authopt.h b/include/net/tcp_authopt.h index 4f83d8e54fef..fda6dc4b5d57 100644 --- a/include/net/tcp_authopt.h +++ b/include/net/tcp_authopt.h @@ -231,10 +231,12 @@ static inline void tcp_authopt_update_snd_sne(struct tcp_sock *tp, u32 seq) lockdep_sock_is_held((struct sock *)tp)); if (info) __tcp_authopt_update_snd_sne(tp, info, seq); } } +int tcp_get_authopt_repair_val(struct sock *sk, struct tcp_authopt_repair *opt); +int tcp_set_authopt_repair(struct sock *sk, sockptr_t optval, unsigned int optlen); #else static inline void tcp_authopt_clear(struct sock *sk) { } static inline int tcp_authopt_openreq(struct sock *newsk, diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h index 5ca8aa9d5e43..ee6836f87cf8 100644 --- a/include/uapi/linux/tcp.h +++ b/include/uapi/linux/tcp.h @@ -128,10 +128,11 @@ enum { #define TCP_CM_INQ TCP_INQ
#define TCP_TX_DELAY 37 /* delay outgoing packets by XX usec */ #define TCP_AUTHOPT 38 /* TCP Authentication Option (RFC5925) */ #define TCP_AUTHOPT_KEY 39 /* TCP Authentication Option Key (RFC5925) */ +#define TCP_REPAIR_AUTHOPT 40
#define TCP_REPAIR_ON 1 #define TCP_REPAIR_OFF 0 #define TCP_REPAIR_OFF_NO_WP -1 /* Turn off without window probes */ @@ -490,10 +491,28 @@ struct tcp_authopt_key { * address match is performed. */ int prefixlen; };
+/** + * struct tcp_authopt_repair - TCP_REPAIR information related to Authentication Option + * @src_isn: Local Initial Sequence Number + * @dst_isn: Remote Initial Sequence Number + * @snd_sne: Sequence Number Extension for Send (upper 32 bits of snd_seq) + * @rcv_sne: Sequence Number Extension for Recv (upper 32 bits of rcv_seq) + * @snd_seq: Recent Send Sequence Number (lower 32 bits of snd_sne) + * @rcv_seq: Recent Recv Sequence Number (lower 32 bits of rcv_sne) + */ +struct tcp_authopt_repair { + __u32 src_isn; + __u32 dst_isn; + __u32 snd_sne; + __u32 rcv_sne; + __u32 snd_seq; + __u32 rcv_seq; +}; + /* setsockopt(fd, IPPROTO_TCP, TCP_ZEROCOPY_RECEIVE, ...) */
#define TCP_RECEIVE_ZEROCOPY_FLAG_TLB_CLEAN_HINT 0x1 struct tcp_zerocopy_receive { __u64 address; /* in: address of mapping */ diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 205534d501ec..ad0af4efd265 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -3715,10 +3715,13 @@ static int do_tcp_setsockopt(struct sock *sk, int level, int optname, err = tcp_set_authopt(sk, optval, optlen); break; case TCP_AUTHOPT_KEY: err = tcp_set_authopt_key(sk, optval, optlen); break; + case TCP_REPAIR_AUTHOPT: + err = tcp_set_authopt_repair(sk, optval, optlen); + break; #endif case TCP_USER_TIMEOUT: /* Cap the max time in ms TCP will retry or probe the window * before giving up and aborting (ETIMEDOUT) a connection. */ @@ -4387,10 +4390,30 @@ static int do_tcp_getsockopt(struct sock *sk, int level, return -EFAULT; if (copy_to_user(optval, &info, len)) return -EFAULT; return 0; } + case TCP_REPAIR_AUTHOPT: { + struct tcp_authopt_repair val; + int err; + + if (get_user(len, optlen)) + return -EFAULT; + + lock_sock(sk); + err = tcp_get_authopt_repair_val(sk, &val); + release_sock(sk); + + if (err) + return err; + len = min_t(unsigned int, len, sizeof(val)); + if (put_user(len, optlen)) + return -EFAULT; + if (copy_to_user(optval, &val, len)) + return -EFAULT; + return 0; + } #endif
default: return -ENOPROTOOPT; } diff --git a/net/ipv4/tcp_authopt.c b/net/ipv4/tcp_authopt.c index 933a4bbddb70..a77067c0498b 100644 --- a/net/ipv4/tcp_authopt.c +++ b/net/ipv4/tcp_authopt.c @@ -1775,10 +1775,76 @@ int __tcp_authopt_inbound_check(struct sock *sk, struct sk_buff *skb,
return 1; } EXPORT_SYMBOL(__tcp_authopt_inbound_check);
+int tcp_get_authopt_repair_val(struct sock *sk, struct tcp_authopt_repair *opt) +{ + struct tcp_sock *tp = tcp_sk(sk); + struct tcp_authopt_info *info; + int err; + + memset(opt, 0, sizeof(*opt)); + sock_owned_by_me(sk); + err = check_sysctl_tcp_authopt(); + if (err) + return err; + if (!tp->repair) + return -EPERM; + + info = rcu_dereference_check(tp->authopt_info, lockdep_sock_is_held(sk)); + if (!info) + return -ENOENT; + + opt->dst_isn = info->dst_isn; + opt->src_isn = info->src_isn; + opt->rcv_sne = info->rcv_sne; + opt->snd_sne = info->snd_sne; + opt->rcv_seq = tp->rcv_nxt; + opt->snd_seq = tp->snd_nxt; + + return 0; +} + +int tcp_set_authopt_repair(struct sock *sk, sockptr_t optval, unsigned int optlen) +{ + struct tcp_sock *tp = tcp_sk(sk); + struct tcp_authopt_info *info; + struct tcp_authopt_repair val; + int err; + + sock_owned_by_me(sk); + err = check_sysctl_tcp_authopt(); + if (err) + return err; + + if (optlen != sizeof(val)) + return -EFAULT; + if (copy_from_sockptr(&val, optval, sizeof(val))) + return -EFAULT; + + /* tcp_authopt repair relies on fields that are only initialized after + * tcp_connect. Doing this setsockopt before connect() can't be correct + * so return an error. + */ + if (sk->sk_state != TCP_ESTABLISHED) + return -EPERM; + + info = rcu_dereference_check(tp->authopt_info, lockdep_sock_is_held(sk)); + if (!info) + return -ENOENT; + if (!tp->repair) + return -EPERM; + + info->dst_isn = val.dst_isn; + info->src_isn = val.src_isn; + info->rcv_sne = compute_sne(val.rcv_sne, val.rcv_seq, tp->rcv_nxt); + info->snd_sne = compute_sne(val.snd_sne, val.snd_seq, tp->snd_nxt); + + return 0; +} + #ifdef CONFIG_PROC_FS struct tcp_authopt_iter_state { struct seq_net_private p; };