[RFC 3/3] ss: restore packet_raw/packet_dgram filtering

The SOCK_RAW/SOCK_DGRAM type check only ever existed in the
/proc/net/packet parser, packet_show_line(), which commit a2b31976
("ss: drop the /proc parsers for packet and netlink sockets")
removed.  The sock_diag path never had it.

packet_show_sock() populates stat.type from pdiag_type but nothing
tested it, and the dispatcher gates on PACKET_DBM, which is the OR of
both bits.  So selecting either type ran an unfiltered dump and
displayed every AF_PACKET socket.  Since packet_show() already
preferred the netlink path, "ss -A packet_raw" has been returning
dgram sockets on any kernel with packet_diag for a long time; the
/proc removal just made it unconditional.

Add packet_type_skip(), mirroring the existing unix_type_skip() and
vsock_type_skip(), and call it from packet_show_sock() once the type
is known.  As before, a socket that is neither SOCK_RAW nor
SOCK_DGRAM falls through both tests and is still displayed.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 misc/ss.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/misc/ss.c b/misc/ss.c
index 7ec72c04..37ed73c4 100644
--- a/misc/ss.c
+++ b/misc/ss.c

@@ -4713,6 +4713,15 @@ static int unix_show(struct filter *f)
 	return 0;
 }
 
+static bool packet_type_skip(struct sockstat *s, const struct filter *f)
+{
+	if (s->type == SOCK_RAW && !(f->dbs & (1 << PACKET_R_DB)))
+		return true;
+	if (s->type == SOCK_DGRAM && !(f->dbs & (1 << PACKET_DG_DB)))
+		return true;
+	return false;
+}
+
 static int packet_stats_print(struct sockstat *s, const struct filter *f)
 {
 	const char *addr, *port;

@@ -4779,6 +4788,9 @@ static int packet_show_sock(struct nlmsghdr *nlh, void *arg)
 	stat.state  = SS_CLOSE;
 	stat.sk	    = cookie_sk_get(&r->pdiag_cookie[0]);
 
+	if (packet_type_skip(&stat, f))
+		return 0;
+
 	if (tb[PACKET_DIAG_MEMINFO]) {
 		__u32 *skmeminfo = RTA_DATA(tb[PACKET_DIAG_MEMINFO]);
 

-- 
2.53.0