route/link: improve handling of IFLA_INET6_CONF

On the netlink API, IFLA_INET6_CONF is a list of uint32_t integers, but
the number of actually provided values depends on the kernel version (and
the DEVCONF_MAX value that it was compiled with.

We clone the kernel header in our source tree, so DEVCONF_MAX from the
libnl3 build may differ from the running kernel. We need to keep track
how many values kernel actually provides.

1 files changed, 12 insertions, 7 deletions

diff --git a/lib/route/link/inet6.c b/lib/route/link/inet6.c
index efb126c..08b29a8 100644
--- a/lib/route/link/inet6.c
+++ b/lib/route/link/inet6.c
@@ -21,6 +21,7 @@ struct inet6_data
 	struct ifla_cacheinfo	i6_cacheinfo;
 	uint32_t		i6_conf[DEVCONF_MAX];
 	struct in6_addr		i6_token;
+	uint8_t			i6_conf_len;
 	uint8_t			i6_addr_gen_mode;
 };
 
@@ -165,9 +166,13 @@ static int inet6_parse_protinfo(struct rtnl_link *link, struct nlattr *attr,
 		nla_memcpy(&i6->i6_cacheinfo, tb[IFLA_INET6_CACHEINFO],
 			   sizeof(i6->i6_cacheinfo));
 
-	if (tb[IFLA_INET6_CONF])
+	if (tb[IFLA_INET6_CONF]) {
+		i6->i6_conf_len = min(ARRAY_SIZE(i6->i6_conf),
+				      nla_len(tb[IFLA_INET6_CONF]) /
+					      sizeof(i6->i6_conf[0]));
 		nla_memcpy(&i6->i6_conf, tb[IFLA_INET6_CONF],
-			   sizeof(i6->i6_conf));
+			   sizeof(i6->i6_conf[0]) * i6->i6_conf_len);
+	}
 
 	if (tb[IFLA_INET6_TOKEN])
 		nla_memcpy(&i6->i6_token, tb[IFLA_INET6_TOKEN],
@@ -351,7 +356,7 @@ static void inet6_dump_details(struct rtnl_link *link,
 	nl_dump_line(p, "      devconf:\n");
 	nl_dump_line(p, "      ");
 
-	for (i = 0; i < DEVCONF_MAX; i++) {
+	for (i = 0; i < (int) i6->i6_conf_len; i++) {
 		char buf2[64];
 		uint32_t value = i6->i6_conf[i];
 		int x, offset;
@@ -699,7 +704,7 @@ int rtnl_link_inet6_set_addr_gen_mode(struct rtnl_link *link, uint8_t mode)
  * result pointer.
  *
  * @return 0 on success or a negative error code.
- * @return -NLE_RANGE cfgid is out of range, 0..DEVCONF_MAX
+ * @return -NLE_RANGE cfgid is out of range or not provided by kernel.
  * @return -NLE_NOATTR configuration setting not available
  */
 int rtnl_link_inet6_get_conf(struct rtnl_link *link, unsigned int cfgid,
@@ -707,12 +712,12 @@ int rtnl_link_inet6_get_conf(struct rtnl_link *link, unsigned int cfgid,
 {
 	struct inet6_data *id;
 
-	if (cfgid >= DEVCONF_MAX)
-		return -NLE_RANGE;
-
 	if (!(id = rtnl_link_af_data(link, &inet6_ops)))
 		return -NLE_NOATTR;
 
+	if (cfgid >= id->i6_conf_len)
+		return -NLE_RANGE;
+
 	*res = id->i6_conf[cfgid];
 
 	return 0;