tcp_send_flag() can return error codes from tcp_prepare_flags()
failing TCP_INFO, or from failure to collect buffers on the
vhost-user path. These errors indicate the connection requires
resetting.
Most callers of tcp_send_flag() were ignoring the error code and
carrying on as if nothing was wrong. Check the return value at
each call site and handle the error appropriately:
- in tcp_data_from_tap(), return -1 so the caller resets
- in tcp_tap_handler(), goto reset
- in tcp_timer_handler()/tcp_sock_handler()/tcp_conn_from_sock_finish(),
call tcp_rst() and return
- in tcp_tap_conn_from_sock(), set CLOSING flag (flow not yet active)
- in tcp_keepalive(), call tcp_rst() and continue the loop
- in tcp_flow_migrate_target_ext(), goto fail
The call in tcp_rst_do() is left unchecked: we are already
resetting, and tcp_sock_rst() still needs to run regardless.
Bug: https://bugs.passt.top/show_bug.cgi?id=194
Signed-off-by: Anshu Kumari
---
tcp.c | 59 ++++++++++++++++++++++++++++++++++++++++++++---------------
1 file changed, 44 insertions(+), 15 deletions(-)
diff --git a/tcp.c b/tcp.c
index 8ea9be8..9ce671a 100644
--- a/tcp.c
+++ b/tcp.c
@@ -1917,7 +1917,9 @@ static int tcp_data_from_tap(const struct ctx *c, struct tcp_tap_conn *conn,
"keep-alive sequence: %u, previous: %u",
seq, conn->seq_from_tap);
- tcp_send_flag(c, conn, ACK);
+ if (tcp_send_flag(c, conn, ACK))
+ return -1;
+
tcp_timer_ctl(c, conn);
if (setsockopt(conn->sock, SOL_SOCKET, SO_KEEPALIVE,
@@ -2043,14 +2045,16 @@ eintr:
* Then swiftly looked away and left.
*/
conn->seq_from_tap = seq_from_tap;
- tcp_send_flag(c, conn, ACK);
+ if (tcp_send_flag(c, conn, ACK))
+ return -1;
}
if (errno == EINTR)
goto eintr;
if (errno == EAGAIN || errno == EWOULDBLOCK) {
- tcp_send_flag(c, conn, ACK | DUP_ACK);
+ if (tcp_send_flag(c, conn, ACK | DUP_ACK))
+ return -1;
return p->count - idx;
}
@@ -2070,7 +2074,8 @@ out:
*/
if (conn->seq_dup_ack_approx != (conn->seq_from_tap & 0xff)) {
conn->seq_dup_ack_approx = conn->seq_from_tap & 0xff;
- tcp_send_flag(c, conn, ACK | DUP_ACK);
+ if (tcp_send_flag(c, conn, ACK | DUP_ACK))
+ return -1;
}
return p->count - idx;
}
@@ -2084,7 +2089,8 @@ out:
conn_event(c, conn, TAP_FIN_RCVD);
} else {
- tcp_send_flag(c, conn, ACK_IF_NEEDED);
+ if (tcp_send_flag(c, conn, ACK_IF_NEEDED))
+ return -1;
}
return p->count - idx;
@@ -2122,7 +2128,10 @@ static void tcp_conn_from_sock_finish(const struct ctx *c,
return;
}
- tcp_send_flag(c, conn, ACK);
+ if (tcp_send_flag(c, conn, ACK)) {
+ tcp_rst(c, conn);
+ return;
+ }
/* The client might have sent data already, which we didn't
* dequeue waiting for SYN,ACK from tap -- check now.
@@ -2308,7 +2317,9 @@ int tcp_tap_handler(const struct ctx *c, uint8_t pif, sa_family_t af,
goto reset;
}
- tcp_send_flag(c, conn, ACK);
+ if (tcp_send_flag(c, conn, ACK))
+ goto reset;
+
conn_event(c, conn, SOCK_FIN_SENT);
return 1;
@@ -2388,7 +2399,9 @@ int tcp_tap_handler(const struct ctx *c, uint8_t pif, sa_family_t af,
}
conn_event(c, conn, SOCK_FIN_SENT);
- tcp_send_flag(c, conn, ACK);
+ if (tcp_send_flag(c, conn, ACK))
+ goto reset;
+
ack_due = 0;
/* If we received a FIN, but the socket is in TCP_ESTABLISHED
@@ -2478,7 +2491,11 @@ static void tcp_tap_conn_from_sock(const struct ctx *c, union flow *flow,
conn->wnd_from_tap = WINDOW_DEFAULT;
- tcp_send_flag(c, conn, SYN);
+ if (tcp_send_flag(c, conn, SYN)) {
+ conn_flag(c, conn, CLOSING);
+ return;
+ }
+
conn_flag(c, conn, ACK_FROM_TAP_DUE);
tcp_get_sndbuf(conn);
@@ -2585,7 +2602,10 @@ void tcp_timer_handler(const struct ctx *c, union epoll_ref ref)
return;
if (conn->flags & ACK_TO_TAP_DUE) {
- tcp_send_flag(c, conn, ACK_IF_NEEDED);
+ if (tcp_send_flag(c, conn, ACK_IF_NEEDED)) {
+ tcp_rst(c, conn);
+ return;
+ }
tcp_timer_ctl(c, conn);
} else if (conn->flags & ACK_FROM_TAP_DUE) {
if (!(conn->events & ESTABLISHED)) {
@@ -2598,7 +2618,10 @@ void tcp_timer_handler(const struct ctx *c, union epoll_ref ref)
tcp_rst(c, conn);
} else {
flow_trace(conn, "SYN timeout, retry");
- tcp_send_flag(c, conn, SYN);
+ if (tcp_send_flag(c, conn, SYN)) {
+ tcp_rst(c, conn);
+ return;
+ }
conn->retries++;
conn_flag(c, conn, SYN_RETRIED);
tcp_timer_ctl(c, conn);
@@ -2662,8 +2685,11 @@ void tcp_sock_handler(const struct ctx *c, union epoll_ref ref,
tcp_data_from_sock(c, conn);
if (events & EPOLLOUT) {
- if (tcp_update_seqack_wnd(c, conn, false, NULL))
- tcp_send_flag(c, conn, ACK);
+ if (tcp_update_seqack_wnd(c, conn, false, NULL) &&
+ tcp_send_flag(c, conn, ACK)) {
+ tcp_rst(c, conn);
+ return;
+ }
}
return;
@@ -2903,7 +2929,8 @@ static void tcp_keepalive(struct ctx *c, const struct timespec *now)
if (conn->tap_inactive) {
flow_dbg(conn, "No tap activity for least %us, send keepalive",
KEEPALIVE_INTERVAL);
- tcp_send_flag(c, conn, KEEPALIVE);
+ if (tcp_send_flag(c, conn, KEEPALIVE))
+ tcp_rst(c, conn);
}
/* Ready to check fot next interval */
@@ -3926,7 +3953,9 @@ int tcp_flow_migrate_target_ext(struct ctx *c, struct tcp_tap_conn *conn, int fd
if (tcp_set_peek_offset(conn, peek_offset))
goto fail;
- tcp_send_flag(c, conn, ACK);
+ if (tcp_send_flag(c, conn, ACK))
+ goto fail;
+
tcp_data_from_sock(c, conn);
if ((rc = tcp_epoll_ctl(conn))) {
--
2.53.0