[IPv4]: FIB configuration using struct fib_config

Introduces struct fib_config replacing the ugly struct kern_rta
prone to ordering issues. Avoids creating faked netlink messages
for auto generated routes or requests via ioctl.

A new interface net/nexthop.h is added to help navigate through
nexthop configuration arrays.

A new struct nl_info will be used to carry the necessary netlink
information to be used for notifications later on.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 294 insertions, 70 deletions

diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index ad4c14f968a1..acc18bdf2dee 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -253,42 +253,190 @@ e_inval:
 
 #ifndef CONFIG_IP_NOSIOCRT
 
+static inline u32 sk_extract_addr(struct sockaddr *addr)
+{
+        return ((struct sockaddr_in *) addr)->sin_addr.s_addr;
+}
+
+static int put_rtax(struct nlattr *mx, int len, int type, u32 value)
+{
+        struct nlattr *nla;
+
+        nla = (struct nlattr *) ((char *) mx + len);
+        nla->nla_type = type;
+        nla->nla_len = nla_attr_size(4);
+        *(u32 *) nla_data(nla) = value;
+
+        return len + nla_total_size(4);
+}
+
+static int rtentry_to_fib_config(int cmd, struct rtentry *rt,
+                                 struct fib_config *cfg)
+{
+        u32 addr;
+        int plen;
+
+        memset(cfg, 0, sizeof(*cfg));
+
+        if (rt->rt_dst.sa_family != AF_INET)
+                return -EAFNOSUPPORT;
+
+        /*
+         * Check mask for validity:
+         * a) it must be contiguous.
+         * b) destination must have all host bits clear.
+         * c) if application forgot to set correct family (AF_INET),
+         *    reject request unless it is absolutely clear i.e.
+         *    both family and mask are zero.
+         */
+        plen = 32;
+        addr = sk_extract_addr(&rt->rt_dst);
+        if (!(rt->rt_flags & RTF_HOST)) {
+                u32 mask = sk_extract_addr(&rt->rt_genmask);
+
+                if (rt->rt_genmask.sa_family != AF_INET) {
+                        if (mask || rt->rt_genmask.sa_family)
+                                return -EAFNOSUPPORT;
+                }
+
+                if (bad_mask(mask, addr))
+                        return -EINVAL;
+
+                plen = inet_mask_len(mask);
+        }
+
+        cfg->fc_dst_len = plen;
+        cfg->fc_dst = addr;
+
+        if (cmd != SIOCDELRT) {
+                cfg->fc_nlflags = NLM_F_CREATE;
+                cfg->fc_protocol = RTPROT_BOOT;
+        }
+
+        if (rt->rt_metric)
+                cfg->fc_priority = rt->rt_metric - 1;
+
+        if (rt->rt_flags & RTF_REJECT) {
+                cfg->fc_scope = RT_SCOPE_HOST;
+                cfg->fc_type = RTN_UNREACHABLE;
+                return 0;
+        }
+
+        cfg->fc_scope = RT_SCOPE_NOWHERE;
+        cfg->fc_type = RTN_UNICAST;
+
+        if (rt->rt_dev) {
+                char *colon;
+                struct net_device *dev;
+                char devname[IFNAMSIZ];
+
+                if (copy_from_user(devname, rt->rt_dev, IFNAMSIZ-1))
+                        return -EFAULT;
+
+                devname[IFNAMSIZ-1] = 0;
+                colon = strchr(devname, ':');
+                if (colon)
+                        *colon = 0;
+                dev = __dev_get_by_name(devname);
+                if (!dev)
+                        return -ENODEV;
+                cfg->fc_oif = dev->ifindex;
+                if (colon) {
+                        struct in_ifaddr *ifa;
+                        struct in_device *in_dev = __in_dev_get_rtnl(dev);
+                        if (!in_dev)
+                                return -ENODEV;
+                        *colon = ':';
+                        for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next)
+                                if (strcmp(ifa->ifa_label, devname) == 0)
+                                        break;
+                        if (ifa == NULL)
+                                return -ENODEV;
+                        cfg->fc_prefsrc = ifa->ifa_local;
+                }
+        }
+
+        addr = sk_extract_addr(&rt->rt_gateway);
+        if (rt->rt_gateway.sa_family == AF_INET && addr) {
+                cfg->fc_gw = addr;
+                if (rt->rt_flags & RTF_GATEWAY &&
+                    inet_addr_type(addr) == RTN_UNICAST)
+                        cfg->fc_scope = RT_SCOPE_UNIVERSE;
+        }
+
+        if (cmd == SIOCDELRT)
+                return 0;
+
+        if (rt->rt_flags & RTF_GATEWAY && !cfg->fc_gw)
+                return -EINVAL;
+
+        if (cfg->fc_scope == RT_SCOPE_NOWHERE)
+                cfg->fc_scope = RT_SCOPE_LINK;
+
+        if (rt->rt_flags & (RTF_MTU | RTF_WINDOW | RTF_IRTT)) {
+                struct nlattr *mx;
+                int len = 0;
+
+                mx = kzalloc(3 * nla_total_size(4), GFP_KERNEL);
+                if (mx == NULL)
+                        return -ENOMEM;
+
+                if (rt->rt_flags & RTF_MTU)
+                        len = put_rtax(mx, len, RTAX_ADVMSS, rt->rt_mtu - 40);
+
+                if (rt->rt_flags & RTF_WINDOW)
+                        len = put_rtax(mx, len, RTAX_WINDOW, rt->rt_window);
+
+                if (rt->rt_flags & RTF_IRTT)
+                        len = put_rtax(mx, len, RTAX_RTT, rt->rt_irtt << 3);
+
+                cfg->fc_mx = mx;
+                cfg->fc_mx_len = len;
+        }
+
+        return 0;
+}
+
 /*
  *      Handle IP routing ioctl calls. These are used to manipulate the routing tables
  */
  
 int ip_rt_ioctl(unsigned int cmd, void __user *arg)
 {
+        struct fib_config cfg;
+        struct rtentry rt;
         int err;
-        struct kern_rta rta;
-        struct rtentry  r;
-        struct {
-                struct nlmsghdr nlh;
-                struct rtmsg    rtm;
-        } req;
 
         switch (cmd) {
         case SIOCADDRT:         /* Add a route */
         case SIOCDELRT:         /* Delete a route */
                 if (!capable(CAP_NET_ADMIN))
                         return -EPERM;
-                if (copy_from_user(&r, arg, sizeof(struct rtentry)))
+
+                if (copy_from_user(&rt, arg, sizeof(rt)))
                         return -EFAULT;
+
                 rtnl_lock();
-                err = fib_convert_rtentry(cmd, &req.nlh, &req.rtm, &rta, &r);
+                err = rtentry_to_fib_config(cmd, &rt, &cfg);
                 if (err == 0) {
+                        struct fib_table *tb;
+
                         if (cmd == SIOCDELRT) {
-                                struct fib_table *tb = fib_get_table(req.rtm.rtm_table);
-                                err = -ESRCH;
+                                tb = fib_get_table(cfg.fc_table);
                                 if (tb)
-                                        err = tb->tb_delete(tb, &req.rtm, &rta, &req.nlh, NULL);
+                                        err = tb->tb_delete(tb, &cfg);
+                                else
+                                        err = -ESRCH;
                         } else {
-                                struct fib_table *tb = fib_new_table(req.rtm.rtm_table);
-                                err = -ENOBUFS;
+                                tb = fib_new_table(cfg.fc_table);
                                 if (tb)
-                                        err = tb->tb_insert(tb, &req.rtm, &rta, &req.nlh, NULL);
+                                        err = tb->tb_insert(tb, &cfg);
+                                else
+                                        err = -ENOBUFS;
                         }
-                        kfree(rta.rta_mx);
+
+                        /* allocated by rtentry_to_fib_config() */
+                        kfree(cfg.fc_mx);
                 }
                 rtnl_unlock();
                 return err;
@@ -305,51 +453,134 @@ int ip_rt_ioctl(unsigned int cmd, void *arg)
 
 #endif
 
-static int inet_check_attr(struct rtmsg *r, struct rtattr **rta)
+static struct nla_policy rtm_ipv4_policy[RTA_MAX+1] __read_mostly = {
+        [RTA_DST]               = { .type = NLA_U32 },
+        [RTA_SRC]               = { .type = NLA_U32 },
+        [RTA_IIF]               = { .type = NLA_U32 },
+        [RTA_OIF]               = { .type = NLA_U32 },
+        [RTA_GATEWAY]           = { .type = NLA_U32 },
+        [RTA_PRIORITY]          = { .type = NLA_U32 },
+        [RTA_PREFSRC]           = { .type = NLA_U32 },
+        [RTA_METRICS]           = { .type = NLA_NESTED },
+        [RTA_MULTIPATH]         = { .minlen = sizeof(struct rtnexthop) },
+        [RTA_PROTOINFO]         = { .type = NLA_U32 },
+        [RTA_FLOW]              = { .type = NLA_U32 },
+        [RTA_MP_ALGO]           = { .type = NLA_U32 },
+};
+
+static int rtm_to_fib_config(struct sk_buff *skb, struct nlmsghdr *nlh,
+                             struct fib_config *cfg)
 {
-        int i;
-
-        for (i=1; i<=RTA_MAX; i++, rta++) {
-                struct rtattr *attr = *rta;
-                if (attr) {
-                        if (RTA_PAYLOAD(attr) < 4)
-                                return -EINVAL;
-                        if (i != RTA_MULTIPATH && i != RTA_METRICS &&
-                            i != RTA_TABLE)
-                                *rta = (struct rtattr*)RTA_DATA(attr);
+        struct nlattr *attr;
+        int err, remaining;
+        struct rtmsg *rtm;
+
+        err = nlmsg_validate(nlh, sizeof(*rtm), RTA_MAX, rtm_ipv4_policy);
+        if (err < 0)
+                goto errout;
+
+        memset(cfg, 0, sizeof(*cfg));
+
+        rtm = nlmsg_data(nlh);
+        cfg->fc_family = rtm->rtm_family;
+        cfg->fc_dst_len = rtm->rtm_dst_len;
+        cfg->fc_src_len = rtm->rtm_src_len;
+        cfg->fc_tos = rtm->rtm_tos;
+        cfg->fc_table = rtm->rtm_table;
+        cfg->fc_protocol = rtm->rtm_protocol;
+        cfg->fc_scope = rtm->rtm_scope;
+        cfg->fc_type = rtm->rtm_type;
+        cfg->fc_flags = rtm->rtm_flags;
+        cfg->fc_nlflags = nlh->nlmsg_flags;
+
+        cfg->fc_nlinfo.pid = NETLINK_CB(skb).pid;
+        cfg->fc_nlinfo.nlh = nlh;
+
+        nlmsg_for_each_attr(attr, nlh, sizeof(struct rtmsg), remaining) {
+                switch (attr->nla_type) {
+                case RTA_DST:
+                        cfg->fc_dst = nla_get_u32(attr);
+                        break;
+                case RTA_SRC:
+                        cfg->fc_src = nla_get_u32(attr);
+                        break;
+                case RTA_OIF:
+                        cfg->fc_oif = nla_get_u32(attr);
+                        break;
+                case RTA_GATEWAY:
+                        cfg->fc_gw = nla_get_u32(attr);
+                        break;
+                case RTA_PRIORITY:
+                        cfg->fc_priority = nla_get_u32(attr);
+                        break;
+                case RTA_PREFSRC:
+                        cfg->fc_prefsrc = nla_get_u32(attr);
+                        break;
+                case RTA_METRICS:
+                        cfg->fc_mx = nla_data(attr);
+                        cfg->fc_mx_len = nla_len(attr);
+                        break;
+                case RTA_MULTIPATH:
+                        cfg->fc_mp = nla_data(attr);
+                        cfg->fc_mp_len = nla_len(attr);
+                        break;
+                case RTA_FLOW:
+                        cfg->fc_flow = nla_get_u32(attr);
+                        break;
+                case RTA_MP_ALGO:
+                        cfg->fc_mp_alg = nla_get_u32(attr);
+                        break;
+                case RTA_TABLE:
+                        cfg->fc_table = nla_get_u32(attr);
+                        break;
                 }
         }
+
         return 0;
+errout:
+        return err;
 }
 
 int inet_rtm_delroute(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
 {
-        struct fib_table * tb;
-        struct rtattr **rta = arg;
-        struct rtmsg *r = NLMSG_DATA(nlh);
+        struct fib_config cfg;
+        struct fib_table *tb;
+        int err;
 
-        if (inet_check_attr(r, rta))
-                return -EINVAL;
+        err = rtm_to_fib_config(skb, nlh, &cfg);
+        if (err < 0)
+                goto errout;
 
-        tb = fib_get_table(rtm_get_table(rta, r->rtm_table));
-        if (tb)
-                return tb->tb_delete(tb, r, (struct kern_rta*)rta, nlh, &NETLINK_CB(skb));
-        return -ESRCH;
+        tb = fib_get_table(cfg.fc_table);
+        if (tb == NULL) {
+                err = -ESRCH;
+                goto errout;
+        }
+
+        err = tb->tb_delete(tb, &cfg);
+errout:
+        return err;
 }
 
 int inet_rtm_newroute(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
 {
-        struct fib_table * tb;
-        struct rtattr **rta = arg;
-        struct rtmsg *r = NLMSG_DATA(nlh);
+        struct fib_config cfg;
+        struct fib_table *tb;
+        int err;
 
-        if (inet_check_attr(r, rta))
-                return -EINVAL;
+        err = rtm_to_fib_config(skb, nlh, &cfg);
+        if (err < 0)
+                goto errout;
 
-        tb = fib_new_table(rtm_get_table(rta, r->rtm_table));
-        if (tb)
-                return tb->tb_insert(tb, r, (struct kern_rta*)rta, nlh, &NETLINK_CB(skb));
-        return -ENOBUFS;
+        tb = fib_new_table(cfg.fc_table);
+        if (tb == NULL) {
+                err = -ENOBUFS;
+                goto errout;
+        }
+
+        err = tb->tb_insert(tb, &cfg);
+errout:
+        return err;
 }
 
 int inet_dump_fib(struct sk_buff *skb, struct netlink_callback *cb)
@@ -396,17 +627,19 @@ out:
    only when netlink is already locked.
  */
 
-static void fib_magic(int cmd, int type, u32 dst, int dst_len, struct in_ifaddr *ifa)
+static void fib_magic(int cmd, int type, u32 dst, int dst_len,
+                      struct in_ifaddr *ifa)
 {
-        struct fib_table * tb;
-        struct {
-                struct nlmsghdr nlh;
-                struct rtmsg    rtm;
-        } req;
-        struct kern_rta rta;
-
-        memset(&req.rtm, 0, sizeof(req.rtm));
-        memset(&rta, 0, sizeof(rta));
+        struct fib_table *tb;
+        struct fib_config cfg = {
+                .fc_protocol = RTPROT_KERNEL,
+                .fc_type = type,
+                .fc_dst = dst,
+                .fc_dst_len = dst_len,
+                .fc_prefsrc = ifa->ifa_local,
+                .fc_oif = ifa->ifa_dev->dev->ifindex,
+                .fc_nlflags = NLM_F_CREATE | NLM_F_APPEND,
+        };
 
         if (type == RTN_UNICAST)
                 tb = fib_new_table(RT_TABLE_MAIN);
@@ -416,26 +649,17 @@ static void fib_magic(int cmd, int type, u32 dst, int dst_len, struct in_ifaddr
         if (tb == NULL)
                 return;
 
-        req.nlh.nlmsg_len = sizeof(req);
-        req.nlh.nlmsg_type = cmd;
-        req.nlh.nlmsg_flags = NLM_F_REQUEST|NLM_F_CREATE|NLM_F_APPEND;
-        req.nlh.nlmsg_pid = 0;
-        req.nlh.nlmsg_seq = 0;
+        cfg.fc_table = tb->tb_id;
 
-        req.rtm.rtm_dst_len = dst_len;
-        req.rtm.rtm_table = tb->tb_id;
-        req.rtm.rtm_protocol = RTPROT_KERNEL;
-        req.rtm.rtm_scope = (type != RTN_LOCAL ? RT_SCOPE_LINK : RT_SCOPE_HOST);
-        req.rtm.rtm_type = type;
-
-        rta.rta_dst = &dst;
-        rta.rta_prefsrc = &ifa->ifa_local;
-        rta.rta_oif = &ifa->ifa_dev->dev->ifindex;
+        if (type != RTN_LOCAL)
+                cfg.fc_scope = RT_SCOPE_LINK;
+        else
+                cfg.fc_scope = RT_SCOPE_HOST;
 
         if (cmd == RTM_NEWROUTE)
-                tb->tb_insert(tb, &req.rtm, &rta, &req.nlh, NULL);
+                tb->tb_insert(tb, &cfg);
         else
-                tb->tb_delete(tb, &req.rtm, &rta, &req.nlh, NULL);
+                tb->tb_delete(tb, &cfg);
 }
 
 void fib_add_ifaddr(struct in_ifaddr *ifa)