platform: don't assume that netlink message is as big as at compile time

The link_stats structure grew between 4.5 and 4.6 and this would cause
the messages to me ignored when compiling with 4.6 headers and running
on 4.5.

https://bugzilla.gnome.org/show_bug.cgi?id=764332

diff --git a/src/platform/nm-linux-platform.c b/src/platform/nm-linux-platform.c
index e2ff1f6..1430159 100644 (file)
--- a/src/platform/nm-linux-platform.c
+++ b/src/platform/nm-linux-platform.c
@@ -55,6 +55,8 @@
 #include "wifi/wifi-utils.h"
 #include "wifi/wifi-utils-wext.h"
 
+#define offset_plus_sizeof(t,m) (offsetof (t,m) + sizeof (((t *) NULL)->m))
+
 #define VLAN_FLAG_MVRP 0x8
 
 /* nm-internal error codes for libnl. Make sure they don't overlap. */
@@ -831,7 +833,7 @@ _parse_af_inet6 (NMPlatform *platform,
 {
        static struct nla_policy policy[IFLA_INET6_MAX+1] = {
                [IFLA_INET6_FLAGS]              = { .type = NLA_U32 },
-               [IFLA_INET6_CACHEINFO]          = { .minlen = sizeof(struct ifla_cacheinfo) },
+               [IFLA_INET6_CACHEINFO]          = { .minlen = offset_plus_sizeof(struct ifla_cacheinfo, retrans_time) },
                [IFLA_INET6_CONF]               = { .minlen = 4 },
                [IFLA_INET6_STATS]              = { .minlen = 8 },
                [IFLA_INET6_ICMP6STATS]         = { .minlen = 8 },
@@ -1242,7 +1244,7 @@ _parse_lnk_vlan (const char *kind, struct nlattr *info_data)
 {
        static struct nla_policy policy[IFLA_VLAN_MAX+1] = {
                [IFLA_VLAN_ID]          = { .type = NLA_U16 },
-               [IFLA_VLAN_FLAGS]       = { .minlen = sizeof(struct ifla_vlan_flags) },
+               [IFLA_VLAN_FLAGS]       = { .minlen = offset_plus_sizeof(struct ifla_vlan_flags, flags) },
                [IFLA_VLAN_INGRESS_QOS] = { .type = NLA_NESTED },
                [IFLA_VLAN_EGRESS_QOS]  = { .type = NLA_NESTED },
                [IFLA_VLAN_PROTOCOL]    = { .type = NLA_U16 },
@@ -1429,9 +1431,9 @@ _new_from_nl_link (NMPlatform *platform, const NMPCache *cache, struct nlmsghdr
                [IFLA_LINKINFO]         = { .type = NLA_NESTED },
                [IFLA_QDISC]            = { .type = NLA_STRING,
                                            .maxlen = IFQDISCSIZ },
-               [IFLA_STATS]            = { .minlen = sizeof(struct rtnl_link_stats) },
-               [IFLA_STATS64]          = { .minlen = sizeof(struct rtnl_link_stats64)},
-               [IFLA_MAP]              = { .minlen = sizeof(struct rtnl_link_ifmap) },
+               [IFLA_STATS]            = { .minlen = offset_plus_sizeof(struct rtnl_link_stats, tx_compressed) },
+               [IFLA_STATS64]          = { .minlen = offset_plus_sizeof(struct rtnl_link_stats64, tx_compressed)},
+               [IFLA_MAP]              = { .minlen = offset_plus_sizeof(struct rtnl_link_ifmap, port) },
                [IFLA_IFALIAS]          = { .type = NLA_STRING, .maxlen = IFALIASZ },
                [IFLA_NUM_VF]           = { .type = NLA_U32 },
                [IFLA_AF_SPEC]          = { .type = NLA_NESTED },
@@ -1612,7 +1614,7 @@ _new_from_nl_addr (struct nlmsghdr *nlh, gboolean id_only)
        static struct nla_policy policy[IFA_MAX+1] = {
                [IFA_LABEL]     = { .type = NLA_STRING,
                                     .maxlen = IFNAMSIZ },
-               [IFA_CACHEINFO] = { .minlen = sizeof(struct ifa_cacheinfo) },
+               [IFA_CACHEINFO] = { .minlen = offset_plus_sizeof(struct ifa_cacheinfo, tstamp) },
        };
        const struct ifaddrmsg *ifa;
        struct nlattr *tb[IFA_MAX+1];
@@ -1726,7 +1728,7 @@ _new_from_nl_route (struct nlmsghdr *nlh, gboolean id_only)
                [RTA_OIF]       = { .type = NLA_U32 },
                [RTA_PRIORITY]  = { .type = NLA_U32 },
                [RTA_FLOW]      = { .type = NLA_U32 },
-               [RTA_CACHEINFO] = { .minlen = sizeof(struct rta_cacheinfo) },
+               [RTA_CACHEINFO] = { .minlen = offset_plus_sizeof(struct rta_cacheinfo, rta_tsage) },
                [RTA_METRICS]   = { .type = NLA_NESTED },
                [RTA_MULTIPATH] = { .type = NLA_NESTED },
        };