On Thu, 27 Jun 2019 20:39:48 +0200
Michal Kubecek <mkube...@suse.cz> wrote:
> >
> > $ ip li set dev enp3s0 alias "Onboard Ethernet"
> > # ip link show "Onboard Ethernet"
> > Device "Onboard Ethernet" does not exist.
> >
> > So it does not really appear to be an alias, it is a label. To be
> > truly useful, it needs to be more than a label, it needs to be a real
> > alias which you can use.
>
> That's exactly what I meant: to be really useful, one should be able to
> use the alias(es) for setting device options, for adding routes, in
> netfilter rules etc.
>
> Michal
The kernel doesn't enforce uniqueness of alias.
Also current kernel RTM_GETLINK doesn't do filter by alias (easily fixed).
If it did, then handling it in iproute would be something like:
diff --git a/lib/ll_map.c b/lib/ll_map.c
index e0ed54bf77c9..c798ba542224 100644
--- a/lib/ll_map.c
+++ b/lib/ll_map.c
@@ -26,15 +26,18 @@
struct ll_cache {
struct hlist_node idx_hash;
struct hlist_node name_hash;
+ struct hlist_node alias_hash;
unsigned flags;
unsigned index;
unsigned short type;
- char name[];
+ char *alias;
+ char name[IFNAMSIZ];
};
#define IDXMAP_SIZE 1024
static struct hlist_head idx_head[IDXMAP_SIZE];
static struct hlist_head name_head[IDXMAP_SIZE];
+static struct hlist_head alias_head[IDXMAP_SIZE];
static struct ll_cache *ll_get_by_index(unsigned index)
{
@@ -77,10 +80,26 @@ static struct ll_cache *ll_get_by_name(const char *name)
return NULL;
}
+static struct ll_cache *ll_get_by_alias(const char *alias)
+{
+ struct hlist_node *n;
+ unsigned h = namehash(alias) & (IDXMAP_SIZE - 1);
+
+ hlist_for_each(n, &alias_head[h]) {
+ struct ll_cache *im
+ = container_of(n, struct ll_cache, alias_hash);
+
+ if (strcmp(im->alias, alias) == 0)
+ return im;
+ }
+
+ return NULL;
+}
+
int ll_remember_index(struct nlmsghdr *n, void *arg)
{
unsigned int h;
- const char *ifname;
+ const char *ifname, *ifalias;
struct ifinfomsg *ifi = NLMSG_DATA(n);
struct ll_cache *im;
struct rtattr *tb[IFLA_MAX+1];
@@ -96,6 +115,10 @@ int ll_remember_index(struct nlmsghdr *n, void *arg)
if (im) {
hlist_del(&im->name_hash);
hlist_del(&im->idx_hash);
+ if (im->alias) {
+ hlist_del(&im->alias_hash);
+ free(im->alias);
+ }
free(im);
}
return 0;
@@ -106,6 +129,8 @@ int ll_remember_index(struct nlmsghdr *n, void *arg)
if (ifname == NULL)
return 0;
+ ifalias = tb[IFLA_IFALIAS] ? rta_getattr_str(tb[IFLA_IFALIAS]) : NULL;
+
if (im) {
/* change to existing entry */
if (strcmp(im->name, ifname) != 0) {
@@ -114,6 +139,14 @@ int ll_remember_index(struct nlmsghdr *n, void *arg)
hlist_add_head(&im->name_hash, &name_head[h]);
}
+ if (im->alias) {
+ hlist_del(&im->alias_hash);
+ if (ifalias) {
+ h = namehash(ifalias) & (IDXMAP_SIZE - 1);
+ hlist_add_head(&im->alias_hash, &alias_head[h]);
+ }
+ }
+
im->flags = ifi->ifi_flags;
return 0;
}
@@ -132,6 +165,12 @@ int ll_remember_index(struct nlmsghdr *n, void *arg)
h = namehash(ifname) & (IDXMAP_SIZE - 1);
hlist_add_head(&im->name_hash, &name_head[h]);
+ if (ifalias) {
+ im->alias = strdup(ifalias);
+ h = namehash(ifalias) & (IDXMAP_SIZE - 1);
+ hlist_add_head(&im->alias_hash, &alias_head[h]);
+ }
+
return 0;
}
@@ -152,7 +191,7 @@ static unsigned int ll_idx_a2n(const char *name)
return idx;
}
-static int ll_link_get(const char *name, int index)
+static int ll_link_get(const char *name, const char *alias, int index)
{
struct {
struct nlmsghdr n;
@@ -176,6 +215,9 @@ static int ll_link_get(const char *name, int index)
if (name)
addattr_l(&req.n, sizeof(req), IFLA_IFNAME, name,
strlen(name) + 1);
+ if (alias)
+ addattr_l(&req.n, sizeof(req), IFLA_IFALIAS, alias,
+ strlen(alias) + 1);
if (rtnl_talk_suppress_rtnl_errmsg(&rth, &req.n, &answer) < 0)
goto out;
@@ -206,7 +248,7 @@ const char *ll_index_to_name(unsigned int idx)
if (im)
return im->name;
- if (ll_link_get(NULL, idx) == idx) {
+ if (ll_link_get(NULL, NULL, idx) == idx) {
im = ll_get_by_index(idx);
if (im)
return im->name;
@@ -252,7 +294,13 @@ unsigned ll_name_to_index(const char *name)
if (im)
return im->index;
- idx = ll_link_get(name, 0);
+ im = ll_get_by_alias(name);
+ if (im)
+ return im->index;
+
+ idx = ll_link_get(name, NULL, 0);
+ if (idx == 0)
+ idx = ll_link_get(NULL, name, 0);
if (idx == 0)
idx = if_nametoindex(name);
if (idx == 0)
@@ -270,7 +318,10 @@ void ll_drop_by_index(unsigned index)
hlist_del(&im->idx_hash);
hlist_del(&im->name_hash);
-
+ if (im->alias) {
+ hlist_del(&im->alias_hash);
+ free(im->alias);
+ }
free(im);
}
