[DECNET] address: Convert to new netlink interface

Extends the netlink interface to support the __le16 type and
converts address addition, deletion and, dumping to use the
new netlink interface.

Fixes multiple occasions of possible illegal memory references
due to not validated netlink attributes.

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

1 files changed, 85 insertions, 57 deletions

diff --git a/net/decnet/dn_dev.c b/net/decnet/dn_dev.c
index 309b2c7a4c6c..0b9d4c955154 100644
--- a/net/decnet/dn_dev.c
+++ b/net/decnet/dn_dev.c
@@ -645,41 +645,62 @@ static struct dn_dev *dn_dev_by_index(int ifindex)
         return dn_dev;
 }
 
-static int dn_dev_rtm_deladdr(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
+static struct nla_policy dn_ifa_policy[IFA_MAX+1] __read_mostly = {
+        [IFA_ADDRESS]           = { .type = NLA_U16 },
+        [IFA_LOCAL]             = { .type = NLA_U16 },
+        [IFA_LABEL]             = { .type = NLA_STRING,
+                                    .len = IFNAMSIZ - 1 },
+};
+
+static int dn_nl_deladdr(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
 {
-        struct rtattr **rta = arg;
+        struct nlattr *tb[IFA_MAX+1];
         struct dn_dev *dn_db;
-        struct ifaddrmsg *ifm = NLMSG_DATA(nlh);
+        struct ifaddrmsg *ifm;
         struct dn_ifaddr *ifa, **ifap;
+        int err = -EADDRNOTAVAIL;
+
+        err = nlmsg_parse(nlh, sizeof(*ifm), tb, IFA_MAX, dn_ifa_policy);
+        if (err < 0)
+                goto errout;
 
+        ifm = nlmsg_data(nlh);
         if ((dn_db = dn_dev_by_index(ifm->ifa_index)) == NULL)
-                return -EADDRNOTAVAIL;
+                goto errout;
+
+        for (ifap = &dn_db->ifa_list; (ifa = *ifap); ifap = &ifa->ifa_next) {
+                if (tb[IFA_LOCAL] &&
+                    nla_memcmp(tb[IFA_LOCAL], &ifa->ifa_local, 2))
+                        continue;
 
-        for(ifap = &dn_db->ifa_list; (ifa=*ifap) != NULL; ifap = &ifa->ifa_next) {
-                void *tmp = rta[IFA_LOCAL-1];
-                if ((tmp && memcmp(RTA_DATA(tmp), &ifa->ifa_local, 2)) ||
-                    (rta[IFA_LABEL-1] && rtattr_strcmp(rta[IFA_LABEL-1], ifa->ifa_label)))
+                if (tb[IFA_LABEL] && nla_strcmp(tb[IFA_LABEL], ifa->ifa_label))
                         continue;
 
                 dn_dev_del_ifa(dn_db, ifap, 1);
                 return 0;
         }
 
-        return -EADDRNOTAVAIL;
+errout:
+        return err;
 }
 
-static int dn_dev_rtm_newaddr(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
+static int dn_nl_newaddr(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
 {
-        struct rtattr **rta = arg;
+        struct nlattr *tb[IFA_MAX+1];
         struct net_device *dev;
         struct dn_dev *dn_db;
-        struct ifaddrmsg *ifm = NLMSG_DATA(nlh);
+        struct ifaddrmsg *ifm;
         struct dn_ifaddr *ifa;
-        int rv;
+        int err;
+
+        err = nlmsg_parse(nlh, sizeof(*ifm), tb, IFA_MAX, dn_ifa_policy);
+        if (err < 0)
+                return err;
 
-        if (rta[IFA_LOCAL-1] == NULL)
+        if (tb[IFA_LOCAL] == NULL)
                 return -EINVAL;
 
+        ifm = nlmsg_data(nlh);
         if ((dev = __dev_get_by_index(ifm->ifa_index)) == NULL)
                 return -ENODEV;
 
@@ -693,22 +714,25 @@ static int dn_dev_rtm_newaddr(struct sk_buff *skb, struct nlmsghdr *nlh, void *a
         if ((ifa = dn_dev_alloc_ifa()) == NULL)
                 return -ENOBUFS;
 
-        if (!rta[IFA_ADDRESS - 1])
-                rta[IFA_ADDRESS - 1] = rta[IFA_LOCAL - 1];
-        memcpy(&ifa->ifa_local, RTA_DATA(rta[IFA_LOCAL-1]), 2);
-        memcpy(&ifa->ifa_address, RTA_DATA(rta[IFA_ADDRESS-1]), 2);
+        if (tb[IFA_ADDRESS] == NULL)
+                tb[IFA_ADDRESS] = tb[IFA_LOCAL];
+
+        ifa->ifa_local = nla_get_le16(tb[IFA_LOCAL]);
+        ifa->ifa_address = nla_get_le16(tb[IFA_ADDRESS]);
         ifa->ifa_flags = ifm->ifa_flags;
         ifa->ifa_scope = ifm->ifa_scope;
         ifa->ifa_dev = dn_db;
-        if (rta[IFA_LABEL-1])
-                rtattr_strlcpy(ifa->ifa_label, rta[IFA_LABEL-1], IFNAMSIZ);
+
+        if (tb[IFA_LABEL])
+                nla_strlcpy(ifa->ifa_label, tb[IFA_LABEL], IFNAMSIZ);
         else
                 memcpy(ifa->ifa_label, dev->name, IFNAMSIZ);
 
-        rv = dn_dev_insert_ifa(dn_db, ifa);
-        if (rv)
+        err = dn_dev_insert_ifa(dn_db, ifa);
+        if (err)
                 dn_dev_free_ifa(ifa);
-        return rv;
+
+        return err;
 }
 
 static inline size_t dn_ifaddr_nlmsg_size(void)
@@ -719,34 +743,34 @@ static inline size_t dn_ifaddr_nlmsg_size(void)
                + nla_total_size(2); /* IFA_LOCAL */
 }
 
-static int dn_dev_fill_ifaddr(struct sk_buff *skb, struct dn_ifaddr *ifa,
-                                u32 pid, u32 seq, int event, unsigned int flags)
+static int dn_nl_fill_ifaddr(struct sk_buff *skb, struct dn_ifaddr *ifa,
+                             u32 pid, u32 seq, int event, unsigned int flags)
 {
         struct ifaddrmsg *ifm;
         struct nlmsghdr *nlh;
-        unsigned char *b = skb->tail;
 
-        nlh = NLMSG_NEW(skb, pid, seq, event, sizeof(*ifm), flags);
-        ifm = NLMSG_DATA(nlh);
+        nlh = nlmsg_put(skb, pid, seq, event, sizeof(*ifm), flags);
+        if (nlh == NULL)
+                return -ENOBUFS;
 
+        ifm = nlmsg_data(nlh);
         ifm->ifa_family = AF_DECnet;
         ifm->ifa_prefixlen = 16;
         ifm->ifa_flags = ifa->ifa_flags | IFA_F_PERMANENT;
         ifm->ifa_scope = ifa->ifa_scope;
         ifm->ifa_index = ifa->ifa_dev->dev->ifindex;
+
         if (ifa->ifa_address)
-                RTA_PUT(skb, IFA_ADDRESS, 2, &ifa->ifa_address);
+                NLA_PUT_LE16(skb, IFA_ADDRESS, ifa->ifa_address);
         if (ifa->ifa_local)
-                RTA_PUT(skb, IFA_LOCAL, 2, &ifa->ifa_local);
+                NLA_PUT_LE16(skb, IFA_LOCAL, ifa->ifa_local);
         if (ifa->ifa_label[0])
-                RTA_PUT(skb, IFA_LABEL, IFNAMSIZ, &ifa->ifa_label);
-        nlh->nlmsg_len = skb->tail - b;
-        return skb->len;
+                NLA_PUT_STRING(skb, IFA_LABEL, ifa->ifa_label);
 
-nlmsg_failure:
-rtattr_failure:
-        skb_trim(skb, b - skb->data);
-        return -1;
+        return nlmsg_end(skb, nlh);
+
+nla_put_failure:
+        return nlmsg_cancel(skb, nlh);
 }
 
 static void dn_ifaddr_notify(int event, struct dn_ifaddr *ifa)
@@ -758,7 +782,7 @@ static void dn_ifaddr_notify(int event, struct dn_ifaddr *ifa)
         if (skb == NULL)
                 goto errout;
 
-        err = dn_dev_fill_ifaddr(skb, ifa, 0, 0, event, 0);
+        err = dn_nl_fill_ifaddr(skb, ifa, 0, 0, event, 0);
         /* failure implies BUG in dn_ifaddr_nlmsg_size() */
         BUG_ON(err < 0);
 
@@ -768,39 +792,43 @@ errout:
                 rtnl_set_sk_err(RTNLGRP_DECnet_IFADDR, err);
 }
 
-static int dn_dev_dump_ifaddr(struct sk_buff *skb, struct netlink_callback *cb)
+static int dn_nl_dump_ifaddr(struct sk_buff *skb, struct netlink_callback *cb)
 {
-        int idx, dn_idx;
-        int s_idx, s_dn_idx;
+        int idx, dn_idx = 0, skip_ndevs, skip_naddr;
         struct net_device *dev;
         struct dn_dev *dn_db;
         struct dn_ifaddr *ifa;
 
-        s_idx = cb->args[0];
-        s_dn_idx = dn_idx = cb->args[1];
+        skip_ndevs = cb->args[0];
+        skip_naddr = cb->args[1];
+
         read_lock(&dev_base_lock);
-        for(dev = dev_base, idx = 0; dev; dev = dev->next, idx++) {
-                if (idx < s_idx)
+        for (dev = dev_base, idx = 0; dev; dev = dev->next, idx++) {
+                if (idx < skip_ndevs)
                         continue;
-                if (idx > s_idx)
-                        s_dn_idx = 0;
+                else if (idx > skip_ndevs) {
+                        /* Only skip over addresses for first dev dumped
+                         * in this iteration (idx == skip_ndevs) */
+                        skip_naddr = 0;
+                }
+
                 if ((dn_db = dev->dn_ptr) == NULL)
                         continue;
 
-                for(ifa = dn_db->ifa_list, dn_idx = 0; ifa; ifa = ifa->ifa_next, dn_idx++) {
-                        if (dn_idx < s_dn_idx)
+                for (ifa = dn_db->ifa_list, dn_idx = 0; ifa;
+                     ifa = ifa->ifa_next, dn_idx++) {
+                        if (dn_idx < skip_naddr)
                                 continue;
 
-                        if (dn_dev_fill_ifaddr(skb, ifa,
-                                               NETLINK_CB(cb->skb).pid,
-                                               cb->nlh->nlmsg_seq,
-                                               RTM_NEWADDR,
-                                               NLM_F_MULTI) <= 0)
+                        if (dn_nl_fill_ifaddr(skb, ifa, NETLINK_CB(cb->skb).pid,
+                                              cb->nlh->nlmsg_seq, RTM_NEWADDR,
+                                              NLM_F_MULTI) < 0)
                                 goto done;
                 }
         }
 done:
         read_unlock(&dev_base_lock);
+
         cb->args[0] = idx;
         cb->args[1] = dn_idx;
 
@@ -1417,9 +1445,9 @@ static struct file_operations dn_dev_seq_fops = {
 
 static struct rtnetlink_link dnet_rtnetlink_table[RTM_NR_MSGTYPES] =
 {
-        [RTM_NEWADDR  - RTM_BASE] = { .doit     = dn_dev_rtm_newaddr,   },
-        [RTM_DELADDR  - RTM_BASE] = { .doit     = dn_dev_rtm_deladdr,   },
-        [RTM_GETADDR  - RTM_BASE] = { .dumpit   = dn_dev_dump_ifaddr,   },
+        [RTM_NEWADDR  - RTM_BASE] = { .doit     = dn_nl_newaddr,        },
+        [RTM_DELADDR  - RTM_BASE] = { .doit     = dn_nl_deladdr,        },
+        [RTM_GETADDR  - RTM_BASE] = { .dumpit   = dn_nl_dump_ifaddr,    },
 #ifdef CONFIG_DECNET_ROUTER
         [RTM_NEWROUTE - RTM_BASE] = { .doit     = dn_fib_rtm_newroute,  },
         [RTM_DELROUTE - RTM_BASE] = { .doit     = dn_fib_rtm_delroute,  },