[PATCH iproute2] ss: do not emit warn while dumping MPTCP on old kernels
From: Paolo Abeni <pabeni@redhat.com>
Date: 2021-01-25 16:05:15
Prior to this commit, running 'ss' on a kernel older than v5.9
bumps an error message:
RTNETLINK answers: Invalid argument
When asked to dump protocol number > 255 - that is: MPTCP - 'ss'
adds an INET_DIAG_REQ_PROTOCOL attribute, unsupported by the older
kernel.
Avoid the warning ignoring filter issues when INET_DIAG_REQ_PROTOCOL
is used.
Additionally older kernel end-up invoking tcpdiag_send(), which
in turn will try to dump DCCP socks. Bail early in such function,
as the kernel does not implement an MPTCPDIAG_GET request.
Reported-by: "Rantala, Tommi T. (Nokia - FI/Espoo)" <redacted>
Fixes: 9c3be2c0eee0 ("ss: mptcp: add msk diag interface support")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
---
misc/ss.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/misc/ss.c b/misc/ss.c
index 0593627b..ad46f9db 100644
--- a/misc/ss.c
+++ b/misc/ss.c@@ -3404,7 +3404,7 @@ static int tcpdiag_send(int fd, int protocol, struct filter *f) struct iovec iov[3]; int iovlen = 1; - if (protocol == IPPROTO_UDP) + if (protocol == IPPROTO_UDP || protocol == IPPROTO_MPTCP) return -1; if (protocol == IPPROTO_TCP)
@@ -3623,6 +3623,14 @@ static int inet_show_netlink(struct filter *f, FILE *dump_fp, int protocol) if (preferred_family == PF_INET6) family = PF_INET6; + /* extended protocol will use INET_DIAG_REQ_PROTOCOL, + * not supported by older kernels. On such kernel + * rtnl_dump will bail with rtnl_dump_error(). + * Suppress the error to avoid confusing the user + */ + if (protocol > 255) + rth.flags |= RTNL_HANDLE_F_SUPPRESS_NLERR; + again: if ((err = sockdiag_send(family, rth.fd, protocol, f))) goto Exit;
--
2.26.2