Merge branch 'tcp_tsoffset'

Andrey Vagin says:

====================
If a TCP socket will get live-migrated from one box to another the
timestamps (which are typically ON) will get screwed up -- the new
kernel will generate TS values that has nothing to do with what they
were on dump. The solution is to yet again fix the kernel and put a
"timestamp offset" on a socket.

A socket offset is added in places where externally visible tcp
timestamp option is parsed/initialized.

Connections in the SYN_RECV state are not supported, global
tcp_time_stamp is used for them, because repair mode doesn't support
this state. In a future it can be implemented by the similar way as for
TIME_WAIT sockets.

For time-wait sockets offset is inhereted by a proper tcp_sock.

A per-socket offset can be set only for sockets in repair mode.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

8 files changed, 47 insertions, 17 deletions

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 6d0d46138ae8..f28408c07dc2 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -162,6 +162,8 @@ struct tcp_sock {
         u32     rcv_tstamp;     /* timestamp of last received ACK (for keepalives) */
         u32     lsndtime;       /* timestamp of last sent data packet (for restart window) */
 
+        u32     tsoffset;       /* timestamp offset */
+
         struct list_head tsq_node; /* anchor in tsq_tasklet.head list */
         unsigned long   tsq_flags;
 
@@ -353,6 +355,7 @@ struct tcp_timewait_sock {
         u32                       tw_rcv_nxt;
         u32                       tw_snd_nxt;
         u32                       tw_rcv_wnd;
+        u32                       tw_ts_offset;
         u32                       tw_ts_recent;
         long                      tw_ts_recent_stamp;
 #ifdef CONFIG_TCP_MD5SIG
diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
index e962faa5ab0d..6b1ead0b0c9d 100644
--- a/include/uapi/linux/tcp.h
+++ b/include/uapi/linux/tcp.h
@@ -111,6 +111,7 @@ enum {
 #define TCP_QUEUE_SEQ           21
 #define TCP_REPAIR_OPTIONS      22
 #define TCP_FASTOPEN            23      /* Enable FastOpen on listeners */
+#define TCP_TIMESTAMP           24
 
 struct tcp_repair_opt {
         __u32   opt_code;
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 2c7e5963c2ea..801b07b796f0 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -400,6 +400,8 @@ void tcp_init_sock(struct sock *sk)
         tcp_enable_early_retrans(tp);
         icsk->icsk_ca_ops = &tcp_init_congestion_ops;
 
+        tp->tsoffset = 0;
+
         sk->sk_state = TCP_CLOSE;
 
         sk->sk_write_space = sk_stream_write_space;
@@ -2712,6 +2714,12 @@ static int do_tcp_setsockopt(struct sock *sk, int level,
                 else
                         err = -EINVAL;
                 break;
+        case TCP_TIMESTAMP:
+                if (!tp->repair)
+                        err = -EPERM;
+                else
+                        tp->tsoffset = val - tcp_time_stamp;
+                break;
         default:
                 err = -ENOPROTOOPT;
                 break;
@@ -2960,6 +2968,9 @@ static int do_tcp_getsockopt(struct sock *sk, int level,
         case TCP_USER_TIMEOUT:
                 val = jiffies_to_msecs(icsk->icsk_user_timeout);
                 break;
+        case TCP_TIMESTAMP:
+                val = tcp_time_stamp + tp->tsoffset;
+                break;
         default:
                 return -ENOPROTOOPT;
         }
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index ea678b62e94f..d9bfaea34322 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3860,7 +3860,7 @@ static bool tcp_parse_aligned_timestamp(struct tcp_sock *tp, const struct tcphdr
                 ++ptr;
                 tp->rx_opt.rcv_tsval = ntohl(*ptr);
                 ++ptr;
-                tp->rx_opt.rcv_tsecr = ntohl(*ptr);
+                tp->rx_opt.rcv_tsecr = ntohl(*ptr) - tp->tsoffset;
                 return true;
         }
         return false;
@@ -3884,7 +3884,11 @@ static bool tcp_fast_parse_options(const struct sk_buff *skb,
                 if (tcp_parse_aligned_timestamp(tp, th))
                         return true;
         }
+
         tcp_parse_options(skb, &tp->rx_opt, hvpp, 1, NULL);
+        if (tp->rx_opt.saw_tstamp)
+                tp->rx_opt.rcv_tsecr -= tp->tsoffset;
+
         return true;
 }
 
@@ -5665,6 +5669,8 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
         int saved_clamp = tp->rx_opt.mss_clamp;
 
         tcp_parse_options(skb, &tp->rx_opt, &hash_location, 0, &foc);
+        if (tp->rx_opt.saw_tstamp)
+                tp->rx_opt.rcv_tsecr -= tp->tsoffset;
 
         if (th->ack) {
                 /* rfc793:
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 0eaf685bddc9..77f5050efc8d 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -726,7 +726,7 @@ release_sk1:
  */
 
 static void tcp_v4_send_ack(struct sk_buff *skb, u32 seq, u32 ack,
-                            u32 win, u32 ts, int oif,
+                            u32 win, u32 tsval, u32 tsecr, int oif,
                             struct tcp_md5sig_key *key,
                             int reply_flags, u8 tos)
 {
@@ -747,12 +747,12 @@ static void tcp_v4_send_ack(struct sk_buff *skb, u32 seq, u32 ack,
 
         arg.iov[0].iov_base = (unsigned char *)&rep;
         arg.iov[0].iov_len  = sizeof(rep.th);
-        if (ts) {
+        if (tsecr) {
                 rep.opt[0] = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
                                    (TCPOPT_TIMESTAMP << 8) |
                                    TCPOLEN_TIMESTAMP);
-                rep.opt[1] = htonl(tcp_time_stamp);
-                rep.opt[2] = htonl(ts);
+                rep.opt[1] = htonl(tsval);
+                rep.opt[2] = htonl(tsecr);
                 arg.iov[0].iov_len += TCPOLEN_TSTAMP_ALIGNED;
         }
 
@@ -767,7 +767,7 @@ static void tcp_v4_send_ack(struct sk_buff *skb, u32 seq, u32 ack,
 
 #ifdef CONFIG_TCP_MD5SIG
         if (key) {
-                int offset = (ts) ? 3 : 0;
+                int offset = (tsecr) ? 3 : 0;
 
                 rep.opt[offset++] = htonl((TCPOPT_NOP << 24) |
                                           (TCPOPT_NOP << 16) |
@@ -802,6 +802,7 @@ static void tcp_v4_timewait_ack(struct sock *sk, struct sk_buff *skb)
 
         tcp_v4_send_ack(skb, tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,
                         tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale,
+                        tcp_time_stamp + tcptw->tw_ts_offset,
                         tcptw->tw_ts_recent,
                         tw->tw_bound_dev_if,
                         tcp_twsk_md5_key(tcptw),
@@ -821,6 +822,7 @@ static void tcp_v4_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
         tcp_v4_send_ack(skb, (sk->sk_state == TCP_LISTEN) ?
                         tcp_rsk(req)->snt_isn + 1 : tcp_sk(sk)->snd_nxt,
                         tcp_rsk(req)->rcv_nxt, req->rcv_wnd,
+                        tcp_time_stamp,
                         req->ts_recent,
                         0,
                         tcp_md5_do_lookup(sk, (union tcp_md5_addr *)&ip_hdr(skb)->daddr,
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index f0409287b5f4..b83a49cc3816 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -102,6 +102,7 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb,
                 tcp_parse_options(skb, &tmp_opt, &hash_location, 0, NULL);
 
                 if (tmp_opt.saw_tstamp) {
+                        tmp_opt.rcv_tsecr       -= tcptw->tw_ts_offset;
                         tmp_opt.ts_recent       = tcptw->tw_ts_recent;
                         tmp_opt.ts_recent_stamp = tcptw->tw_ts_recent_stamp;
                         paws_reject = tcp_paws_reject(&tmp_opt, th->rst);
@@ -288,6 +289,7 @@ void tcp_time_wait(struct sock *sk, int state, int timeo)
                 tcptw->tw_rcv_wnd       = tcp_receive_window(tp);
                 tcptw->tw_ts_recent     = tp->rx_opt.ts_recent;
                 tcptw->tw_ts_recent_stamp = tp->rx_opt.ts_recent_stamp;
+                tcptw->tw_ts_offset     = tp->tsoffset;
 
 #if IS_ENABLED(CONFIG_IPV6)
                 if (tw->tw_family == PF_INET6) {
@@ -499,6 +501,7 @@ struct sock *tcp_create_openreq_child(struct sock *sk, struct request_sock *req,
                         newtp->rx_opt.ts_recent_stamp = 0;
                         newtp->tcp_header_len = sizeof(struct tcphdr);
                 }
+                newtp->tsoffset = 0;
 #ifdef CONFIG_TCP_MD5SIG
                 newtp->md5sig_info = NULL;      /*XXX*/
                 if (newtp->af_specific->md5_lookup(sk, newsk))
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 367e2ec01da1..564bf89d9fd3 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -622,7 +622,7 @@ static unsigned int tcp_syn_options(struct sock *sk, struct sk_buff *skb,
 
         if (likely(sysctl_tcp_timestamps && *md5 == NULL)) {
                 opts->options |= OPTION_TS;
-                opts->tsval = TCP_SKB_CB(skb)->when;
+                opts->tsval = TCP_SKB_CB(skb)->when + tp->tsoffset;
                 opts->tsecr = tp->rx_opt.ts_recent;
                 remaining -= TCPOLEN_TSTAMP_ALIGNED;
         }
@@ -806,7 +806,7 @@ static unsigned int tcp_established_options(struct sock *sk, struct sk_buff *skb
 
         if (likely(tp->rx_opt.tstamp_ok)) {
                 opts->options |= OPTION_TS;
-                opts->tsval = tcb ? tcb->when : 0;
+                opts->tsval = tcb ? tcb->when + tp->tsoffset : 0;
                 opts->tsecr = tp->rx_opt.ts_recent;
                 size += TCPOLEN_TSTAMP_ALIGNED;
         }
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index bbb28ae7e5f3..9b6460055df5 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -713,7 +713,8 @@ static const struct tcp_request_sock_ops tcp_request_sock_ipv6_ops = {
 #endif
 
 static void tcp_v6_send_response(struct sk_buff *skb, u32 seq, u32 ack, u32 win,
-                                 u32 ts, struct tcp_md5sig_key *key, int rst, u8 tclass)
+                                 u32 tsval, u32 tsecr,
+                                 struct tcp_md5sig_key *key, int rst, u8 tclass)
 {
         const struct tcphdr *th = tcp_hdr(skb);
         struct tcphdr *t1;
@@ -725,7 +726,7 @@ static void tcp_v6_send_response(struct sk_buff *skb, u32 seq, u32 ack, u32 win,
         struct dst_entry *dst;
         __be32 *topt;
 
-        if (ts)
+        if (tsecr)
                 tot_len += TCPOLEN_TSTAMP_ALIGNED;
 #ifdef CONFIG_TCP_MD5SIG
         if (key)
@@ -755,11 +756,11 @@ static void tcp_v6_send_response(struct sk_buff *skb, u32 seq, u32 ack, u32 win,
 
         topt = (__be32 *)(t1 + 1);
 
-        if (ts) {
+        if (tsecr) {
                 *topt++ = htonl((TCPOPT_NOP << 24) | (TCPOPT_NOP << 16) |
                                 (TCPOPT_TIMESTAMP << 8) | TCPOLEN_TIMESTAMP);
-                *topt++ = htonl(tcp_time_stamp);
-                *topt++ = htonl(ts);
+                *topt++ = htonl(tsval);
+                *topt++ = htonl(tsecr);
         }
 
 #ifdef CONFIG_TCP_MD5SIG
@@ -860,7 +861,7 @@ static void tcp_v6_send_reset(struct sock *sk, struct sk_buff *skb)
                 ack_seq = ntohl(th->seq) + th->syn + th->fin + skb->len -
                           (th->doff << 2);
 
-        tcp_v6_send_response(skb, seq, ack_seq, 0, 0, key, 1, 0);
+        tcp_v6_send_response(skb, seq, ack_seq, 0, 0, 0, key, 1, 0);
 
 #ifdef CONFIG_TCP_MD5SIG
 release_sk1:
@@ -871,10 +872,11 @@ release_sk1:
 #endif
 }
 
-static void tcp_v6_send_ack(struct sk_buff *skb, u32 seq, u32 ack, u32 win, u32 ts,
+static void tcp_v6_send_ack(struct sk_buff *skb, u32 seq, u32 ack,
+                            u32 win, u32 tsval, u32 tsecr,
                             struct tcp_md5sig_key *key, u8 tclass)
 {
-        tcp_v6_send_response(skb, seq, ack, win, ts, key, 0, tclass);
+        tcp_v6_send_response(skb, seq, ack, win, tsval, tsecr, key, 0, tclass);
 }
 
 static void tcp_v6_timewait_ack(struct sock *sk, struct sk_buff *skb)
@@ -884,6 +886,7 @@ static void tcp_v6_timewait_ack(struct sock *sk, struct sk_buff *skb)
 
         tcp_v6_send_ack(skb, tcptw->tw_snd_nxt, tcptw->tw_rcv_nxt,
                         tcptw->tw_rcv_wnd >> tw->tw_rcv_wscale,
+                        tcp_time_stamp + tcptw->tw_ts_offset,
                         tcptw->tw_ts_recent, tcp_twsk_md5_key(tcptw),
                         tw->tw_tclass);
 
@@ -893,7 +896,8 @@ static void tcp_v6_timewait_ack(struct sock *sk, struct sk_buff *skb)
 static void tcp_v6_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
                                   struct request_sock *req)
 {
-        tcp_v6_send_ack(skb, tcp_rsk(req)->snt_isn + 1, tcp_rsk(req)->rcv_isn + 1, req->rcv_wnd, req->ts_recent,
+        tcp_v6_send_ack(skb, tcp_rsk(req)->snt_isn + 1, tcp_rsk(req)->rcv_isn + 1,
+                        req->rcv_wnd, tcp_time_stamp, req->ts_recent,
                         tcp_v6_md5_do_lookup(sk, &ipv6_hdr(skb)->daddr), 0);
 }