netdev - [patch iproute2-next v2 2/2] ip: allow to use alternative names as handle

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Date:   Wed,  2 Oct 2019 12:56:45 +0200
From:   Jiri Pirko <jiri@...nulli.us>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, jakub.kicinski@...ronome.com,
        dsahern@...il.com, roopa@...ulusnetworks.com, dcbw@...hat.com,
        nikolay@...ulusnetworks.com, mkubecek@...e.cz, andrew@...n.ch,
        parav@...lanox.com, saeedm@...lanox.com, f.fainelli@...il.com,
        stephen@...workplumber.org, sd@...asysnail.net, sbrivio@...hat.com,
        pabeni@...hat.com, mlxsw@...lanox.com
Subject: [patch iproute2-next v2 2/2] ip: allow to use alternative names as handle

From: Jiri Pirko <jiri@...lanox.com>

Extend ll_name_to_index() to get the index of a netdevice using
alternative interface name. Allow alternative long names to pass checks
in couple of ip link/addr commands.

Signed-off-by: Jiri Pirko <jiri@...lanox.com>
---
rfc->v1:
- added patch description
---
 ip/iplink.c  |  5 +++--
 lib/ll_map.c | 41 ++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 43 insertions(+), 3 deletions(-)

diff --git a/ip/iplink.c b/ip/iplink.c
index e3f8a28fe94c..1684e259b538 100644
--- a/ip/iplink.c
+++ b/ip/iplink.c
@@ -931,7 +931,7 @@ int iplink_parse(int argc, char **argv, struct iplink_req *req, char **type)
 				NEXT_ARG();
 			if (dev != name)
 				duparg2("dev", *argv);
-			if (check_ifname(*argv))
+			if (check_altifname(*argv))
 				invarg("\"dev\" not a valid ifname", *argv);
 			dev = *argv;
 		}
@@ -1106,7 +1106,8 @@ int iplink_get(char *name, __u32 filt_mask)
 
 	if (name) {
 		addattr_l(&req.n, sizeof(req),
-			  IFLA_IFNAME, name, strlen(name) + 1);
+			  !check_ifname(name) ? IFLA_IFNAME : IFLA_ALT_IFNAME,
+			  name, strlen(name) + 1);
 	}
 	addattr32(&req.n, sizeof(req), IFLA_EXT_MASK, filt_mask);
 
diff --git a/lib/ll_map.c b/lib/ll_map.c
index e0ed54bf77c9..04dfb0f2320b 100644
--- a/lib/ll_map.c
+++ b/lib/ll_map.c
@@ -70,7 +70,7 @@ static struct ll_cache *ll_get_by_name(const char *name)
 		struct ll_cache *im
 			= container_of(n, struct ll_cache, name_hash);
 
-		if (strncmp(im->name, name, IFNAMSIZ) == 0)
+		if (strcmp(im->name, name) == 0)
 			return im;
 	}
 
@@ -240,6 +240,43 @@ int ll_index_to_flags(unsigned idx)
 	return im ? im->flags : -1;
 }
 
+static int altnametoindex(const char *name)
+{
+	struct {
+		struct nlmsghdr		n;
+		struct ifinfomsg	ifm;
+		char			buf[1024];
+	} req = {
+		.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg)),
+		.n.nlmsg_flags = NLM_F_REQUEST,
+		.n.nlmsg_type = RTM_GETLINK,
+	};
+	struct rtnl_handle rth = {};
+	struct nlmsghdr *answer;
+	struct ifinfomsg *ifm;
+	int rc = 0;
+
+	if (rtnl_open(&rth, 0) < 0)
+		return 0;
+
+	addattr32(&req.n, sizeof(req), IFLA_EXT_MASK,
+		  RTEXT_FILTER_VF | RTEXT_FILTER_SKIP_STATS);
+	addattr_l(&req.n, sizeof(req), IFLA_ALT_IFNAME, name, strlen(name) + 1);
+
+	if (rtnl_talk_suppress_rtnl_errmsg(&rth, &req.n, &answer) < 0)
+		goto out;
+
+	ifm = NLMSG_DATA(answer);
+	rc = ifm->ifi_index;
+
+	free(answer);
+
+	rtnl_close(&rth);
+out:
+	return rc;
+}
+
+
 unsigned ll_name_to_index(const char *name)
 {
 	const struct ll_cache *im;
@@ -257,6 +294,8 @@ unsigned ll_name_to_index(const char *name)
 		idx = if_nametoindex(name);
 	if (idx == 0)
 		idx = ll_idx_a2n(name);
+	if (idx == 0)
+		idx = altnametoindex(name);
 	return idx;
 }
 
-- 
2.21.0