From 28772ee91a60b34786023496ea17c2c2f4e5f7f5 Mon Sep 17 00:00:00 2001 From: David Gibson Date: Wed, 19 Mar 2025 16:14:21 +1100 Subject: migrate, tcp: More careful marshalling of mss parameter during migration During migration we extract the limit on segment size using TCP_MAXSEG, and set it on the other side with TCP_REPAIR_OPTIONS. However, unlike most 32-bit values we transfer we transfer it in native endian, not network endian. This is not correct; add it to the list of endian fixups we make. In addition, while MAXSEG will be 32-bits in practice, and is given as such to TCP_REPAIR_OPTIONS, the TCP_MAXSEG sockopt treats it as an 'int'. It's not strictly safe to pass a uint32_t to a getsockopt() expecting an int, although we'll get away with it on most (maybe all) platforms. Correct this as well. Signed-off-by: David Gibson [sbrivio: Minor coding style fix] Signed-off-by: Stefano Brivio --- tcp.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/tcp.c b/tcp.c index a4c840e..43ee76b 100644 --- a/tcp.c +++ b/tcp.c @@ -2848,13 +2848,16 @@ static int tcp_flow_dump_mss(const struct tcp_tap_conn *conn, struct tcp_tap_transfer_ext *t) { socklen_t sl = sizeof(t->mss); + int val; - if (getsockopt(conn->sock, SOL_TCP, TCP_MAXSEG, &t->mss, &sl)) { + if (getsockopt(conn->sock, SOL_TCP, TCP_MAXSEG, &val, &sl)) { int rc = -errno; flow_perror(conn, "Getting MSS"); return rc; } + t->mss = (uint32_t)val; + return 0; } @@ -3301,6 +3304,7 @@ int tcp_flow_migrate_source_ext(int fd, const struct tcp_tap_conn *conn) t->sndq = htonl(t->sndq); t->notsent = htonl(t->notsent); t->rcvq = htonl(t->rcvq); + t->mss = htonl(t->mss); t->snd_wl1 = htonl(t->snd_wl1); t->snd_wnd = htonl(t->snd_wnd); @@ -3514,6 +3518,7 @@ int tcp_flow_migrate_target_ext(struct ctx *c, struct tcp_tap_conn *conn, int fd t.sndq = ntohl(t.sndq); t.notsent = ntohl(t.notsent); t.rcvq = ntohl(t.rcvq); + t.mss = ntohl(t.mss); t.snd_wl1 = ntohl(t.snd_wl1); t.snd_wnd = ntohl(t.snd_wnd); -- cgit v1.2.3