Re: ss command not showing raw sockets? (regression)

On Tue, 17 Aug 2021 13:54:53 -0600 David Ahern wrote:

quoted

On 8/17/21 12:44 PM, Jakub Kicinski wrote:

quoted

quoted

@kuba With PROC_NET_RAW I consider the problem is found, isn't it? So
I will not download/bisect<->build or otherwise investigate the
problem until one of you explicitely asks me to do so.

I have now redirected invocation of command with set PROC_NET_RAW on
my system, and may (try to) update to Linux 4.19.  

I suspect the bisection would end up at the commit which added 
the netlink dump support, so you can hold off for now, yes.  

agreed.

quoted

My best guess right now is that Knoppix has a cut-down kernel 
config and we don't handle that case correctly.
  

CONFIG_INET_RAW_DIAG (or INET_DIAG) is probably disabled. surprised the
netlink dump does not return an error and it falls back to the proc file:

        if (!getenv("PROC_NET_RAW") && !getenv("PROC_ROOT") &&
            inet_show_netlink(f, NULL, IPPROTO_RAW) == 0)
                return 0;

can you strace it?

Ah, good point, strace will show it. 

/me goes off to look at the strace Jonas sent off list.

Well this is unexpected:

sendmsg(3, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, msg_namelen=12, msg_iov=[{iov_base={{len=76, type=DCCPDIAG_GETSOCK, ...

--->8----------------

From: Jakub Kicinski <kuba@kernel.org>
Subject: ss: fix fallback to procfs for raw and sctp sockets

sockdiag_send() diverts to tcpdiag_send() to try the older
netlink interface. tcpdiag_send() works for TCP and DCCP
but not other protocols. Instead of rejecting unsupported
protocols (and missing RAW and SCTP) match on supported ones.

Fixes: 41fe6c34de50 ("ss: Add inet raw sockets information gathering via netlink diag interface")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
 misc/ss.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/misc/ss.c b/misc/ss.c
index 894ad40574f1..b39f63fe3b17 100644
--- a/misc/ss.c
+++ b/misc/ss.c

@@ -3404,13 +3404,13 @@ static int tcpdiag_send(int fd, int protocol, struct filter *f)
 	struct iovec iov[3];
 	int iovlen = 1;
 
-	if (protocol == IPPROTO_UDP || protocol == IPPROTO_MPTCP)
-		return -1;
-
 	if (protocol == IPPROTO_TCP)
 		req.nlh.nlmsg_type = TCPDIAG_GETSOCK;
-	else
+	else if (protocol == IPPROTO_DCCP)
 		req.nlh.nlmsg_type = DCCPDIAG_GETSOCK;
+	else
+		return -1;
+
 	if (show_mem) {
 		req.r.idiag_ext |= (1<<(INET_DIAG_MEMINFO-1));
 		req.r.idiag_ext |= (1<<(INET_DIAG_SKMEMINFO-1));