[PATCH iproute2 2/2] ss: print MD5 signature keys configured on TCP sockets

[Ivan Delalande]

These keys are reported by kernel 4.14 and later under the
INET_DIAG_MD5SIG attribute, when INET_DIAG_INFO is requested (ss -i)
and we have CAP_NET_ADMIN. The additional output looks like:

        md5keys:fe80::/64=signing_key,10.1.2.0/24=foobar,::1/128=Test

Signed-off-by: Ivan Delalande <col...@arista.com>
---
 misc/ss.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/misc/ss.c b/misc/ss.c
index dd8dfaa4..09bff8a7 100644
--- a/misc/ss.c
+++ b/misc/ss.c
@@ -2153,6 +2153,16 @@ static void print_skmeminfo(struct rtattr *tb[], int 
attrtype)
        printf(")");
 }
 
+static void print_md5sig(struct tcp_diag_md5sig *sig)
+{
+       printf("%s/%d=",
+              format_host(sig->tcpm_family,
+                          sig->tcpm_family == AF_INET6 ? 16 : 4,
+                          &sig->tcpm_addr),
+              sig->tcpm_prefixlen);
+       print_escape_buf(sig->tcpm_key, sig->tcpm_keylen, " ,");
+}
+
 #define TCPI_HAS_OPT(info, opt) !!(info->tcpi_options & (opt))
 
 static void tcp_show_info(const struct nlmsghdr *nlh, struct inet_diag_msg *r,
@@ -2289,6 +2299,17 @@ static void tcp_show_info(const struct nlmsghdr *nlh, 
struct inet_diag_msg *r,
                free(s.dctcp);
                free(s.bbr_info);
        }
+       if (tb[INET_DIAG_MD5SIG]) {
+               struct tcp_diag_md5sig *sig = RTA_DATA(tb[INET_DIAG_MD5SIG]);
+               int len = RTA_PAYLOAD(tb[INET_DIAG_MD5SIG]);
+
+               printf(" md5keys:");
+               print_md5sig(sig++);
+               for (len -= sizeof(*sig); len > 0; len -= sizeof(*sig)) {
+                       printf(",");
+                       print_md5sig(sig++);
+               }
+       }
 }
 
 static const char *format_host_sa(struct sockaddr_storage *sa)
-- 
2.14.2