From a3093182758eb58116eb5b400f3c44acef571056 Mon Sep 17 00:00:00 2001 From: David Gibson Date: Thu, 3 Aug 2023 17:19:52 +1000 Subject: netlink: Add nl_foreach_oftype to filter response message types In most cases where processing response messages, we expect only one type of message (excepting NLMSG_DONE or NLMSG_ERROR), and so we need a test and continue to skip anything else. Add a helper macro to do this. This also fixes a bug in nl_get_ext_if() where we didn't have such a test and if we got a message other than RTM_NEWROUTE we would have parsed its contents as nonsense. Also add a warning message if we get such an unexpected message type, which could be useful for debugging if we ever hit it. Signed-off-by: David Gibson Signed-off-by: Stefano Brivio --- netlink.c | 29 ++++++++++++++--------------- 1 file changed, 14 insertions(+), 15 deletions(-) (limited to 'netlink.c') diff --git a/netlink.c b/netlink.c index 539a223..6a2bab2 100644 --- a/netlink.c +++ b/netlink.c @@ -210,17 +210,25 @@ static struct nlmsghdr *nl_next(int s, char *buf, struct nlmsghdr *nh, ssize_t * /** * nl_foreach - 'for' type macro to step through netlink response messages + * nl_foreach_oftype - as above, but only messages of expected type * @nh: Steps through each response header (struct nlmsghdr *) * @status: When loop exits indicates if there was an error (ssize_t) * @s: Netlink socket * @buf: Buffer for responses (at least NLBUFSIZ long) * @seq: Sequence number of request we're getting responses for - */ + * @type: Type of netlink message to process + */ #define nl_foreach(nh, status, s, buf, seq) \ for ((nh) = nl_next((s), (buf), NULL, &(status)); \ ((status) = nl_status((nh), (status), (seq))) > 0; \ (nh) = nl_next((s), (buf), (nh), &(status))) +#define nl_foreach_oftype(nh, status, s, buf, seq, type) \ + nl_foreach((nh), (status), (s), (buf), (seq)) \ + if ((nh)->nlmsg_type != (type)) { \ + warn("netlink: Unexpected message type"); \ + } else + /** * nl_do() - Send netlink "do" request, and wait for acknowledgement * @s: Netlink socket @@ -269,7 +277,7 @@ unsigned int nl_get_ext_if(int s, sa_family_t af) size_t na; seq = nl_send(s, &req, RTM_GETROUTE, NLM_F_DUMP, sizeof(req)); - nl_foreach(nh, status, s, buf, seq) { + nl_foreach_oftype(nh, status, s, buf, seq, RTM_NEWROUTE) { struct rtmsg *rtm = (struct rtmsg *)NLMSG_DATA(nh); if (rtm->rtm_dst_len || rtm->rtm_family != af) @@ -321,14 +329,11 @@ void nl_route_get_def(int s, unsigned int ifi, sa_family_t af, void *gw) uint16_t seq; seq = nl_send(s, &req, RTM_GETROUTE, NLM_F_DUMP, sizeof(req)); - nl_foreach(nh, status, s, buf, seq) { + nl_foreach_oftype(nh, status, s, buf, seq, RTM_NEWROUTE) { struct rtmsg *rtm = (struct rtmsg *)NLMSG_DATA(nh); struct rtattr *rta; size_t na; - if (nh->nlmsg_type != RTM_NEWROUTE) - continue; - if (rtm->rtm_dst_len) continue; @@ -518,14 +523,11 @@ void nl_addr_get(int s, unsigned int ifi, sa_family_t af, uint16_t seq; seq = nl_send(s, &req, RTM_GETADDR, NLM_F_DUMP, sizeof(req)); - nl_foreach(nh, status, s, buf, seq) { + nl_foreach_oftype(nh, status, s, buf, seq, RTM_NEWADDR) { struct ifaddrmsg *ifa = (struct ifaddrmsg *)NLMSG_DATA(nh); struct rtattr *rta; size_t na; - if (nh->nlmsg_type != RTM_NEWADDR) - continue; - if (ifa->ifa_index != ifi) continue; @@ -639,7 +641,7 @@ void nl_addr_dup(int s_src, unsigned int ifi_src, uint16_t seq; seq = nl_send(s_src, &req, RTM_GETADDR, NLM_F_DUMP, sizeof(req)); - nl_foreach(nh, status, s_src, buf, seq) { + nl_foreach_oftype(nh, status, s_src, buf, seq, RTM_NEWADDR) { struct ifaddrmsg *ifa; struct rtattr *rta; size_t na; @@ -688,14 +690,11 @@ void nl_link_get_mac(int s, unsigned int ifi, void *mac) uint16_t seq; seq = nl_send(s, &req, RTM_GETLINK, 0, sizeof(req)); - nl_foreach(nh, status, s, buf, seq) { + nl_foreach_oftype(nh, status, s, buf, seq, RTM_NEWLINK) { struct ifinfomsg *ifm = (struct ifinfomsg *)NLMSG_DATA(nh); struct rtattr *rta; size_t na; - if (nh->nlmsg_type != RTM_NEWLINK) - continue; - for (rta = IFLA_RTA(ifm), na = RTM_PAYLOAD(nh); RTA_OK(rta, na); rta = RTA_NEXT(rta, na)) { -- cgit v1.2.3