chiark / gitweb /
rtnl: fix memory corruptions after realloc
[elogind.git] / src / libsystemd-rtnl / rtnl-message.c
index 06c7622f7c936bf9dd7c9f6077156176d308cc35..517df611563f057fc96e3721e56343837e305386 100644 (file)
@@ -35,15 +35,16 @@ struct sd_rtnl_message {
         RefCount n_ref;
 
         struct nlmsghdr *hdr;
-
-        struct rtattr *current_container;
-
-        struct rtattr *next_rta;
-        size_t remaining_size;
+        size_t container_offset; /* offset from hdr to container start */
+        size_t next_rta_offset; /* offset from hdr to next rta */
 
         bool sealed:1;
 };
 
+#define CURRENT_CONTAINER(m) ((m)->container_offset ? (struct rtattr*)((uint8_t*)(m)->hdr + (m)->container_offset) : NULL)
+#define NEXT_RTA(m) ((struct rtattr*)((uint8_t*)(m)->hdr + (m)->next_rta_offset))
+#define UPDATE_RTA(m, new) (m)->next_rta_offset = (uint8_t*)(new) - (uint8_t*)(m)->hdr;
+
 static int message_new(sd_rtnl_message **ret, size_t initial_size) {
         sd_rtnl_message *m;
 
@@ -91,16 +92,57 @@ int message_new_synthetic_error(int error, uint32_t serial, sd_rtnl_message **re
         return 0;
 }
 
+bool message_type_is_route(uint16_t type) {
+        switch (type) {
+                case RTM_NEWROUTE:
+                case RTM_GETROUTE:
+                case RTM_DELROUTE:
+                        return true;
+                default:
+                        return false;
+        }
+}
+
+bool message_type_is_link(uint16_t type) {
+        switch (type) {
+                case RTM_NEWLINK:
+                case RTM_SETLINK:
+                case RTM_GETLINK:
+                case RTM_DELLINK:
+                        return true;
+                default:
+                        return false;
+        }
+}
+
+bool message_type_is_addr(uint16_t type) {
+        switch (type) {
+                case RTM_NEWADDR:
+                case RTM_GETADDR:
+                case RTM_DELADDR:
+                        return true;
+                default:
+                        return false;
+        }
+}
+
+int sd_rtnl_message_route_set_dst_prefixlen(sd_rtnl_message *m, unsigned char prefixlen) {
+        struct rtmsg *rtm;
+
+        rtm = NLMSG_DATA(m->hdr);
+
+        rtm->rtm_dst_len = prefixlen;
+
+        return 0;
+}
+
 int sd_rtnl_message_route_new(uint16_t nlmsg_type, unsigned char rtm_family,
-                              unsigned char rtm_dst_len, unsigned char rtm_src_len,
-                              unsigned char rtm_tos, unsigned char rtm_table,
-                              unsigned char rtm_scope, unsigned char rtm_protocol,
-                              unsigned char rtm_type, unsigned rtm_flags, sd_rtnl_message **ret) {
+                              sd_rtnl_message **ret) {
         struct rtmsg *rtm;
         int r;
 
-        assert_return(nlmsg_type == RTM_NEWROUTE || nlmsg_type == RTM_DELROUTE ||
-                      nlmsg_type == RTM_GETROUTE, -EINVAL);
+        assert_return(message_type_is_route(nlmsg_type), -EINVAL);
+        assert_return(rtm_family == AF_INET || rtm_family == AF_INET6, -EINVAL);
         assert_return(ret, -EINVAL);
 
         r = message_new(ret, NLMSG_SPACE(sizeof(struct rtmsg)));
@@ -114,25 +156,42 @@ int sd_rtnl_message_route_new(uint16_t nlmsg_type, unsigned char rtm_family,
 
         rtm = NLMSG_DATA((*ret)->hdr);
 
+        UPDATE_RTA(*ret, RTM_RTA(rtm));
+
         rtm->rtm_family = rtm_family;
-        rtm->rtm_dst_len = rtm_dst_len;
-        rtm->rtm_src_len = rtm_src_len;
-        rtm->rtm_tos = rtm_tos;
-        rtm->rtm_table = rtm_table;
-        rtm->rtm_protocol = rtm_protocol;
-        rtm->rtm_scope = rtm_scope;
-        rtm->rtm_type = rtm_type;
-        rtm->rtm_flags = rtm_flags;
+        rtm->rtm_scope = RT_SCOPE_UNIVERSE;
+        rtm->rtm_type = RTN_UNICAST;
+        rtm->rtm_table = RT_TABLE_MAIN;
+        rtm->rtm_protocol = RTPROT_BOOT;
+
+        return 0;
+}
+
+int sd_rtnl_message_link_set_flags(sd_rtnl_message *m, unsigned flags) {
+        struct ifinfomsg *ifi;
+
+        ifi = NLMSG_DATA(m->hdr);
+
+        ifi->ifi_flags = flags;
 
         return 0;
 }
 
-int sd_rtnl_message_link_new(uint16_t nlmsg_type, int index, unsigned int type, unsigned int flags, sd_rtnl_message **ret) {
+int sd_rtnl_message_link_set_type(sd_rtnl_message *m, unsigned type) {
+        struct ifinfomsg *ifi;
+
+        ifi = NLMSG_DATA(m->hdr);
+
+        ifi->ifi_type = type;
+
+        return 0;
+}
+
+int sd_rtnl_message_link_new(uint16_t nlmsg_type, int index, sd_rtnl_message **ret) {
         struct ifinfomsg *ifi;
         int r;
 
-        assert_return(nlmsg_type == RTM_NEWLINK || nlmsg_type == RTM_DELLINK ||
-                      nlmsg_type == RTM_SETLINK || nlmsg_type == RTM_GETLINK, -EINVAL);
+        assert_return(message_type_is_link(nlmsg_type), -EINVAL);
         assert_return(nlmsg_type == RTM_NEWLINK || index > 0, -EINVAL);
         assert_return(ret, -EINVAL);
 
@@ -149,10 +208,10 @@ int sd_rtnl_message_link_new(uint16_t nlmsg_type, int index, unsigned int type,
 
         ifi->ifi_family = AF_UNSPEC;
         ifi->ifi_index = index;
-        ifi->ifi_type = type;
-        ifi->ifi_flags = flags;
         ifi->ifi_change = 0xffffffff;
 
+        UPDATE_RTA(*ret, IFLA_RTA(ifi));
+
         return 0;
 }
 
@@ -160,7 +219,7 @@ int sd_rtnl_message_addr_new(uint16_t nlmsg_type, int index, unsigned char famil
         struct ifaddrmsg *ifa;
         int r;
 
-        assert_return(nlmsg_type == RTM_NEWADDR || nlmsg_type == RTM_DELADDR || nlmsg_type == RTM_GETADDR, -EINVAL);
+        assert_return(message_type_is_addr(nlmsg_type), -EINVAL);
         assert_return(index > 0, -EINVAL);
         assert_return(ret, -EINVAL);
 
@@ -179,6 +238,8 @@ int sd_rtnl_message_addr_new(uint16_t nlmsg_type, int index, unsigned char famil
         ifa->ifa_scope = scope;
         ifa->ifa_index = index;
 
+        UPDATE_RTA(*ret, IFA_RTA(ifa));
+
         return 0;
 }
 
@@ -211,9 +272,9 @@ int sd_rtnl_message_link_get_ifindex(sd_rtnl_message *m, int *ifindex) {
         struct ifinfomsg *ifi;
 
         assert_return(m, -EINVAL);
+        assert_return(m->hdr, -EINVAL);
+        assert_return(message_type_is_link(m->hdr->nlmsg_type), -EINVAL);
         assert_return(ifindex, -EINVAL);
-        assert_return(m->hdr->nlmsg_type == RTM_NEWLINK || m->hdr->nlmsg_type == RTM_DELLINK ||
-                      m->hdr->nlmsg_type == RTM_GETLINK || m->hdr->nlmsg_type == RTM_SETLINK, -EINVAL);
 
         ifi = NLMSG_DATA(m->hdr);
 
@@ -222,8 +283,23 @@ int sd_rtnl_message_link_get_ifindex(sd_rtnl_message *m, int *ifindex) {
         return 0;
 }
 
-/* If successful the updated message will be correctly aligned, if unsuccessful the old message is
-   untouched */
+int sd_rtnl_message_link_get_flags(sd_rtnl_message *m, unsigned *flags) {
+        struct ifinfomsg *ifi;
+
+        assert_return(m, -EINVAL);
+        assert_return(m->hdr, -EINVAL);
+        assert_return(message_type_is_link(m->hdr->nlmsg_type), -EINVAL);
+        assert_return(flags, -EINVAL);
+
+        ifi = NLMSG_DATA(m->hdr);
+
+        *flags = ifi->ifi_flags;
+
+        return 0;
+}
+
+/* If successful the updated message will be correctly aligned, if
+   unsuccessful the old message is untouched. */
 static int add_rtattr(sd_rtnl_message *m, unsigned short type, const void *data, size_t data_length) {
         uint32_t rta_length, message_length;
         struct nlmsghdr *new_hdr;
@@ -237,8 +313,8 @@ static int add_rtattr(sd_rtnl_message *m, unsigned short type, const void *data,
 
         /* get the size of the new rta attribute (with padding at the end) */
         rta_length = RTA_LENGTH(data_length);
-        /* get the new message size (with padding at the end)
-         */
+
+        /* get the new message size (with padding at the end) */
         message_length = m->hdr->nlmsg_len + RTA_ALIGN(rta_length);
 
         /* realloc to fit the new attribute */
@@ -249,183 +325,326 @@ static int add_rtattr(sd_rtnl_message *m, unsigned short type, const void *data,
 
         /* get pointer to the attribute we are about to add */
         rta = (struct rtattr *) ((uint8_t *) m->hdr + m->hdr->nlmsg_len);
-        /* update message size */
-        m->hdr->nlmsg_len = message_length;
 
-        /* we are inside a container, extend it */
-        if (m->current_container)
-                m->current_container->rta_len = (unsigned char *) m->hdr +
-                                                m->hdr->nlmsg_len -
-                                                (unsigned char *) m->current_container;
+        /* if we are inside a container, extend it */
+        if (CURRENT_CONTAINER(m))
+                CURRENT_CONTAINER(m)->rta_len += message_length - m->hdr->nlmsg_len;
 
         /* fill in the attribute */
         rta->rta_type = type;
         rta->rta_len = rta_length;
         if (!data) {
-                /* this is a container, set pointer */
-                m->current_container = rta;
+                /* this is the start of a new container */
+                m->container_offset = m->hdr->nlmsg_len;
         } else {
                 /* we don't deal with the case where the user lies about the type
                  * and gives us too little data (so don't do that)
                 */
                 padding = mempcpy(RTA_DATA(rta), data, data_length);
                 /* make sure also the padding at the end of the message is initialized */
-                memset(padding, '\0', (unsigned char *) m->hdr +
-                                      m->hdr->nlmsg_len -
-                                      (unsigned char *) padding);
+                memzero(padding,
+                        (uint8_t *) m->hdr + message_length - (uint8_t *) padding);
         }
 
+        /* update message size */
+        m->hdr->nlmsg_len = message_length;
+
         return 0;
 }
 
-int sd_rtnl_message_append(sd_rtnl_message *m, unsigned short type, const void *data) {
+int sd_rtnl_message_append_string(sd_rtnl_message *m, unsigned short type, const char *data) {
         uint16_t rtm_type;
-        struct ifaddrmsg *ifa;
-        struct rtmsg *rtm;
+        int r;
 
         assert_return(m, -EINVAL);
         assert_return(data, -EINVAL);
 
-        sd_rtnl_message_get_type(m, &rtm_type);
+        r = sd_rtnl_message_get_type(m, &rtm_type);
+        if (r < 0)
+                return r;
 
-        if (m->current_container) {
-                switch (rtm_type) {
-                        case RTM_NEWLINK:
-                        case RTM_SETLINK:
-                        case RTM_GETLINK:
-                        case RTM_DELLINK:
-                                switch (m->current_container->rta_type) {
-                                        case IFLA_LINKINFO:
-                                                switch (type) {
-                                                        case IFLA_INFO_KIND:
-                                                                return add_rtattr(m, type, data, strlen(data) + 1);
-                                                        default:
-                                                                return -ENOTSUP;
-                                                }
+        /* check that the type is correct */
+        switch (rtm_type) {
+                case RTM_NEWLINK:
+                case RTM_SETLINK:
+                case RTM_GETLINK:
+                case RTM_DELLINK:
+                        if (CURRENT_CONTAINER(m)) {
+                                if (CURRENT_CONTAINER(m)->rta_type != IFLA_LINKINFO ||
+                                    type != IFLA_INFO_KIND)
+                                        return -ENOTSUP;
+                        } else {
+                                switch (type) {
+                                        case IFLA_IFNAME:
+                                        case IFLA_IFALIAS:
+                                        case IFLA_QDISC:
+                                                break;
                                         default:
                                                 return -ENOTSUP;
                                 }
-                        default:
+                        }
+                        break;
+                case RTM_NEWADDR:
+                case RTM_GETADDR:
+                case RTM_DELADDR:
+                        if (type != IFA_LABEL)
                                 return -ENOTSUP;
-                }
+                        break;
+                default:
+                        return -ENOTSUP;
         }
 
+        r = add_rtattr(m, type, data, strlen(data) + 1);
+        if (r < 0)
+                return r;
+
+        return 0;
+}
+
+int sd_rtnl_message_append_u32(sd_rtnl_message *m, unsigned short type, uint32_t data) {
+        uint16_t rtm_type;
+        int r;
+
+        assert_return(m, -EINVAL);
+
+        r = sd_rtnl_message_get_type(m, &rtm_type);
+        if (r < 0)
+                return r;
+
+        /* check that the type is correct */
         switch (rtm_type) {
                 case RTM_NEWLINK:
                 case RTM_SETLINK:
-                case RTM_DELLINK:
                 case RTM_GETLINK:
+                case RTM_DELLINK:
                         switch (type) {
-                                case IFLA_IFNAME:
-                                case IFLA_IFALIAS:
-                                case IFLA_QDISC:
-                                        return add_rtattr(m, type, data, strlen(data) + 1);
                                 case IFLA_MASTER:
                                 case IFLA_MTU:
                                 case IFLA_LINK:
-                                        return add_rtattr(m, type, data, sizeof(uint32_t));
-                                case IFLA_STATS:
-                                        return add_rtattr(m, type, data, sizeof(struct rtnl_link_stats));
-                                case IFLA_ADDRESS:
-                                case IFLA_BROADCAST:
-                                        return add_rtattr(m, type, data, ETH_ALEN);
+                                        break;
                                 default:
                                         return -ENOTSUP;
                         }
+                        break;
+                case RTM_NEWROUTE:
+                case RTM_GETROUTE:
+                case RTM_DELROUTE:
+                        switch (type) {
+                                case RTA_TABLE:
+                                case RTA_PRIORITY:
+                                case RTA_IIF:
+                                case RTA_OIF:
+                                        break;
+                                default:
+                                        return -ENOTSUP;
+                        }
+                        break;
+                default:
+                        return -ENOTSUP;
+        }
+
+        r = add_rtattr(m, type, &data, sizeof(uint32_t));
+        if (r < 0)
+                return r;
+
+        return 0;
+}
+
+int sd_rtnl_message_append_in_addr(sd_rtnl_message *m, unsigned short type, const struct in_addr *data) {
+        struct ifaddrmsg *ifa;
+        struct rtmsg *rtm;
+        uint16_t rtm_type;
+        int r;
+
+        assert_return(m, -EINVAL);
+        assert_return(data, -EINVAL);
+
+        r = sd_rtnl_message_get_type(m, &rtm_type);
+        if (r < 0)
+                return r;
+
+        /* check that the type is correct */
+        switch (rtm_type) {
                 case RTM_NEWADDR:
-                case RTM_DELADDR:
                 case RTM_GETADDR:
+                case RTM_DELADDR:
                         switch (type) {
-                                case IFA_LABEL:
-                                        return add_rtattr(m, type, data, strlen(data) + 1);
                                 case IFA_ADDRESS:
                                 case IFA_LOCAL:
                                 case IFA_BROADCAST:
                                 case IFA_ANYCAST:
                                         ifa = NLMSG_DATA(m->hdr);
-                                        switch (ifa->ifa_family) {
-                                                case AF_INET:
-                                                        return add_rtattr(m, type, data, sizeof(struct in_addr));
-                                                case AF_INET6:
-                                                        return add_rtattr(m, type, data, sizeof(struct in6_addr));
-                                                default:
-                                                        return -EINVAL;
-                                        }
+
+                                        if (ifa->ifa_family != AF_INET)
+                                                return -EINVAL;
+
+                                        break;
                                 default:
                                         return -ENOTSUP;
                         }
+                        break;
                 case RTM_NEWROUTE:
+                case RTM_GETROUTE:
                 case RTM_DELROUTE:
+                        switch (type) {
+                                case RTA_DST:
+                                case RTA_SRC:
+                                case RTA_GATEWAY:
+                                        rtm = NLMSG_DATA(m->hdr);
+
+                                        if (rtm->rtm_family != AF_INET)
+                                                return -EINVAL;
+
+                                        break;
+                                default:
+                                        return -ENOTSUP;
+                        }
+                        break;
+                default:
+                        return -ENOTSUP;
+        }
+
+        r = add_rtattr(m, type, data, sizeof(struct in_addr));
+        if (r < 0)
+                return r;
+
+        return 0;
+}
+
+int sd_rtnl_message_append_in6_addr(sd_rtnl_message *m, unsigned short type, const struct in6_addr *data) {
+        struct ifaddrmsg *ifa;
+        struct rtmsg *rtm;
+        uint16_t rtm_type;
+        int r;
+
+        assert_return(m, -EINVAL);
+        assert_return(data, -EINVAL);
+
+        r = sd_rtnl_message_get_type(m, &rtm_type);
+        if (r < 0)
+                return r;
+
+        /* check that the type is correct */
+        switch (rtm_type) {
+                case RTM_NEWADDR:
+                case RTM_GETADDR:
+                case RTM_DELADDR:
+                        switch (type) {
+                                case IFA_ADDRESS:
+                                case IFA_LOCAL:
+                                case IFA_BROADCAST:
+                                case IFA_ANYCAST:
+                                        ifa = NLMSG_DATA(m->hdr);
+
+                                        if (ifa->ifa_family != AF_INET6)
+                                                return -EINVAL;
+
+                                        break;
+                                default:
+                                        return -ENOTSUP;
+                        }
+                        break;
+                case RTM_NEWROUTE:
                 case RTM_GETROUTE:
+                case RTM_DELROUTE:
                         switch (type) {
                                 case RTA_DST:
                                 case RTA_SRC:
                                 case RTA_GATEWAY:
                                         rtm = NLMSG_DATA(m->hdr);
-                                        switch (rtm->rtm_family) {
-                                                case AF_INET:
-                                                        return add_rtattr(m, type, data, sizeof(struct in_addr));
-                                                case AF_INET6:
-                                                        return add_rtattr(m, type, data, sizeof(struct in6_addr));
-                                                default:
-                                                        return -EINVAL;
-                                        }
-                                case RTA_TABLE:
-                                case RTA_PRIORITY:
-                                case RTA_IIF:
-                                case RTA_OIF:
-                                        return add_rtattr(m, type, data, sizeof(uint32_t));
+
+                                        if (rtm->rtm_family != AF_INET6)
+                                                return -EINVAL;
+
+                                        break;
                                 default:
                                         return -ENOTSUP;
                         }
                 default:
                         return -ENOTSUP;
         }
+
+        r = add_rtattr(m, type, data, sizeof(struct in6_addr));
+        if (r < 0)
+                return r;
+
+        return 0;
 }
 
-int sd_rtnl_message_open_container(sd_rtnl_message *m, unsigned short type) {
+int sd_rtnl_message_append_ether_addr(sd_rtnl_message *m, unsigned short type, const struct ether_addr *data) {
         uint16_t rtm_type;
+        int r;
 
         assert_return(m, -EINVAL);
-        assert_return(!m->current_container, -EINVAL);
+        assert_return(data, -EINVAL);
 
         sd_rtnl_message_get_type(m, &rtm_type);
 
         switch (rtm_type) {
                 case RTM_NEWLINK:
                 case RTM_SETLINK:
-                case RTM_GETLINK:
                 case RTM_DELLINK:
-                        if (type == IFLA_LINKINFO)
-                                return add_rtattr(m, type, NULL, 0);
-                        else
-                                return -ENOTSUP;
+                case RTM_GETLINK:
+                        switch (type) {
+                                case IFLA_ADDRESS:
+                                case IFLA_BROADCAST:
+                                        break;
+                                default:
+                                        return -ENOTSUP;
+                        }
+                        break;
                 default:
                         return -ENOTSUP;
         }
 
+        r = add_rtattr(m, type, data, ETH_ALEN);
+        if (r < 0)
+                return r;
+
+        return 0;
+}
+
+int sd_rtnl_message_open_container(sd_rtnl_message *m, unsigned short type) {
+        uint16_t rtm_type;
+
+        assert_return(m, -EINVAL);
+        assert_return(!CURRENT_CONTAINER(m), -EINVAL);
+
+        sd_rtnl_message_get_type(m, &rtm_type);
+
+        if (message_type_is_link(rtm_type)) {
+                if (type == IFLA_LINKINFO)
+                        return add_rtattr(m, type, NULL, 0);
+                else
+                        return -ENOTSUP;
+        } else
+                return -ENOTSUP;
+
         return 0;
 }
 
 int sd_rtnl_message_close_container(sd_rtnl_message *m) {
         assert_return(m, -EINVAL);
-        assert_return(m->current_container, -EINVAL);
+        assert_return(CURRENT_CONTAINER(m), -EINVAL);
 
-        m->current_container = NULL;
+        m->container_offset = 0;
 
         return 0;
 }
 
-static int message_read(sd_rtnl_message *m, unsigned short *type, void **data) {
+int sd_rtnl_message_read(sd_rtnl_message *m, unsigned short *type, void **data) {
+        size_t remaining_size;
         uint16_t rtm_type;
         int r;
 
         assert(m);
-        assert(m->next_rta);
+        assert(m->next_rta_offset);
         assert(type);
         assert(data);
 
-        if (!RTA_OK(m->next_rta, m->remaining_size))
+        remaining_size = m->hdr->nlmsg_len - m->next_rta_offset;
+
+        if (!RTA_OK(NEXT_RTA(m), remaining_size))
                 return 0;
 
         /* make sure we don't try to read a container
@@ -434,76 +653,21 @@ static int message_read(sd_rtnl_message *m, unsigned short *type, void **data) {
         if (r < 0)
                 return r;
 
-        switch (rtm_type) {
-                case RTM_NEWLINK:
-                case RTM_GETLINK:
-                case RTM_SETLINK:
-                case RTM_DELLINK:
-                        if (m->next_rta->rta_type == IFLA_LINKINFO) {
-                                return -EINVAL;
-                        }
-        }
+        if (message_type_is_link(rtm_type) &&
+            NEXT_RTA(m)->rta_type == IFLA_LINKINFO)
+               return -EINVAL;
 
-        *data = RTA_DATA(m->next_rta);
-        *type = m->next_rta->rta_type;
+        *data = RTA_DATA(NEXT_RTA(m));
+        *type = NEXT_RTA(m)->rta_type;
 
-        m->next_rta = RTA_NEXT(m->next_rta, m->remaining_size);
+        UPDATE_RTA(m, RTA_NEXT(NEXT_RTA(m), remaining_size));
 
         return 1;
 }
 
-int sd_rtnl_message_read(sd_rtnl_message *m, unsigned short *type, void **data) {
-        uint16_t rtm_type;
-        int r;
-
-        assert_return(m, -EINVAL);
-        assert_return(data, -EINVAL);
-
-        r = sd_rtnl_message_get_type(m, &rtm_type);
-        if (r < 0)
-                return r;
-
-        switch (rtm_type) {
-                case RTM_NEWLINK:
-                case RTM_SETLINK:
-                case RTM_DELLINK:
-                case RTM_GETLINK:
-                        if (!m->next_rta) {
-                                struct ifinfomsg *ifi = NLMSG_DATA(m->hdr);
-
-                                m->next_rta = IFLA_RTA(ifi);
-                                m->remaining_size = IFLA_PAYLOAD(m->hdr);
-                        }
-                        break;
-                case RTM_NEWADDR:
-                case RTM_DELADDR:
-                case RTM_GETADDR:
-                        if (!m->next_rta) {
-                                struct ifaddrmsg *ifa = NLMSG_DATA(m->hdr);
-
-                                m->next_rta = IFA_RTA(ifa);
-                                m->remaining_size = IFA_PAYLOAD(m->hdr);
-                        }
-                        break;
-                case RTM_NEWROUTE:
-                case RTM_DELROUTE:
-                case RTM_GETROUTE:
-                        if (!m->next_rta) {
-                                struct rtmesg *rtm = NLMSG_DATA(m->hdr);
-
-                                m->next_rta = RTM_RTA(rtm);
-                                m->remaining_size = RTM_PAYLOAD(m->hdr);
-                        }
-                        break;
-                default:
-                        return -ENOTSUP;
-        }
-
-        return message_read(m, type, data);
-}
-
 uint32_t message_get_serial(sd_rtnl_message *m) {
         assert(m);
+        assert(m->hdr);
 
         return m->hdr->nlmsg_seq;
 }
@@ -512,6 +676,7 @@ int sd_rtnl_message_get_errno(sd_rtnl_message *m) {
         struct nlmsgerr *err;
 
         assert_return(m, -EINVAL);
+        assert_return(m->hdr, -EINVAL);
 
         if (m->hdr->nlmsg_type != NLMSG_ERROR)
                 return 0;
@@ -522,6 +687,10 @@ int sd_rtnl_message_get_errno(sd_rtnl_message *m) {
 }
 
 int message_seal(sd_rtnl *nl, sd_rtnl_message *m) {
+        assert(nl);
+        assert(m);
+        assert(m->hdr);
+
         if (m->sealed)
                 return -EPERM;
 
@@ -532,8 +701,8 @@ int message_seal(sd_rtnl *nl, sd_rtnl_message *m) {
 }
 
 static int message_receive_need(sd_rtnl *rtnl, size_t *need) {
-        assert_return(rtnl, -EINVAL);
-        assert_return(need, -EINVAL);
+        assert(rtnl);
+        assert(need);
 
         /* ioctl(rtnl->fd, FIONREAD, &need)
            Does not appear to work on netlink sockets. libnl uses
@@ -561,8 +730,9 @@ int socket_write_message(sd_rtnl *nl, sd_rtnl_message *m) {
         };
         ssize_t k;
 
-        assert_return(nl, -EINVAL);
-        assert_return(m, -EINVAL);
+        assert(nl);
+        assert(m);
+        assert(m->hdr);
 
         k = sendto(nl->fd, m->hdr, m->hdr->nlmsg_len,
                         0, &addr.sa, sizeof(addr));
@@ -588,8 +758,8 @@ int socket_read_message(sd_rtnl *nl, sd_rtnl_message **ret) {
         ssize_t k;
         size_t need;
 
-        assert_return(nl, -EINVAL);
-        assert_return(ret, -EINVAL);
+        assert(nl);
+        assert(ret);
 
         r = message_receive_need(nl, &need);
         if (r < 0)
@@ -620,6 +790,10 @@ int socket_read_message(sd_rtnl *nl, sd_rtnl_message **ret) {
 
         if (k > 0)
                 switch (m->hdr->nlmsg_type) {
+                        struct ifinfomsg *ifi;
+                        struct ifaddrmsg *ifa;
+                        struct rtmsg *rtm;
+
                         /* check that the size matches the message type */
                         case NLMSG_ERROR:
                                 if (m->hdr->nlmsg_len < NLMSG_LENGTH(sizeof(struct nlmsgerr)))
@@ -631,12 +805,30 @@ int socket_read_message(sd_rtnl *nl, sd_rtnl_message **ret) {
                         case RTM_GETLINK:
                                 if (m->hdr->nlmsg_len < NLMSG_LENGTH(sizeof(struct ifinfomsg)))
                                         k = -EIO;
+                                else {
+                                        ifi = NLMSG_DATA(m->hdr);
+                                        UPDATE_RTA(m, IFLA_RTA(ifi));
+                                }
                                 break;
                         case RTM_NEWADDR:
                         case RTM_DELADDR:
                         case RTM_GETADDR:
                                 if (m->hdr->nlmsg_len < NLMSG_LENGTH(sizeof(struct ifaddrmsg)))
                                         k = -EIO;
+                                else {
+                                        ifa = NLMSG_DATA(m->hdr);
+                                        UPDATE_RTA(m, IFA_RTA(ifa));
+                                }
+                                break;
+                        case RTM_NEWROUTE:
+                        case RTM_DELROUTE:
+                        case RTM_GETROUTE:
+                                if (m->hdr->nlmsg_len < NLMSG_LENGTH(sizeof(struct rtmsg)))
+                                        k = -EIO;
+                                else {
+                                        rtm = NLMSG_DATA(m->hdr);
+                                        UPDATE_RTA(m, RTM_RTA(rtm));
+                                }
                                 break;
                         case NLMSG_NOOP:
                                 k = 0;
@@ -655,3 +847,41 @@ int socket_read_message(sd_rtnl *nl, sd_rtnl_message **ret) {
 
         return k;
 }
+
+int sd_rtnl_message_rewind(sd_rtnl_message *m) {
+        struct ifinfomsg *ifi;
+        struct ifaddrmsg *ifa;
+        struct rtmsg *rtm;
+
+        assert_return(m, -EINVAL);
+        assert_return(m->hdr, -EINVAL);
+
+        switch(m->hdr->nlmsg_type) {
+                case RTM_NEWLINK:
+                case RTM_SETLINK:
+                case RTM_GETLINK:
+                case RTM_DELLINK:
+                        ifi = NLMSG_DATA(m->hdr);
+                        UPDATE_RTA(m, IFLA_RTA(ifi));
+
+                        break;
+                case RTM_NEWADDR:
+                case RTM_GETADDR:
+                case RTM_DELADDR:
+                        ifa = NLMSG_DATA(m->hdr);
+                        UPDATE_RTA(m, IFA_RTA(ifa));
+
+                        break;
+                case RTM_NEWROUTE:
+                case RTM_GETROUTE:
+                case RTM_DELROUTE:
+                        rtm = NLMSG_DATA(m->hdr);
+                        UPDATE_RTA(m, RTM_RTA(rtm));
+
+                        break;
+                default:
+                        return -ENOTSUP;
+        }
+
+        return 0;
+}