tipc: convert legacy nl bearer dump to nl compat

Introduce a framework for dumping netlink data from the new netlink
API and formatting it to the old legacy API format. This is done by
looping the dump data and calling a format handler for each entity, in
this case a bearer.

We dump until either all data is dumped or we reach the limited buffer
size of the legacy API. Remember, the legacy API doesn't scale.

In this commit we convert TIPC_CMD_GET_BEARER_NAMES to use the compat
layer.

Signed-off-by: Richard Alpe <richard.alpe@ericsson.com>
Reviewed-by: Erik Hugne <erik.hugne@ericsson.com>
Reviewed-by: Ying Xue <ying.xue@windriver.com>
Reviewed-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 273 insertions, 34 deletions

diff --git a/net/tipc/bearer.c b/net/tipc/bearer.c
index 35d400e8c2e5..7a9e29641e61 100644
--- a/net/tipc/bearer.c
+++ b/net/tipc/bearer.c
@@ -205,35 +205,6 @@ struct tipc_bearer *tipc_bearer_find(struct net *net, const char *name)
         return NULL;
 }
 
-/**
- * tipc_bearer_get_names - record names of bearers in buffer
- */
-struct sk_buff *tipc_bearer_get_names(struct net *net)
-{
-        struct tipc_net *tn = net_generic(net, tipc_net_id);
-        struct sk_buff *buf;
-        struct tipc_bearer *b;
-        int i, j;
-
-        buf = tipc_cfg_reply_alloc(MAX_BEARERS * TLV_SPACE(TIPC_MAX_BEARER_NAME));
-        if (!buf)
-                return NULL;
-
-        for (i = 0; media_info_array[i] != NULL; i++) {
-                for (j = 0; j < MAX_BEARERS; j++) {
-                        b = rtnl_dereference(tn->bearer_list[j]);
-                        if (!b)
-                                continue;
-                        if (b->media == media_info_array[i]) {
-                                tipc_cfg_append_tlv(buf, TIPC_TLV_BEARER_NAME,
-                                                    b->name,
-                                                    strlen(b->name) + 1);
-                        }
-                }
-        }
-        return buf;
-}
-
 void tipc_bearer_add_dest(struct net *net, u32 bearer_id, u32 dest)
 {
         struct tipc_net *tn = net_generic(net, tipc_net_id);
diff --git a/net/tipc/bearer.h b/net/tipc/bearer.h
index c035e3e24764..956858276d93 100644
--- a/net/tipc/bearer.h
+++ b/net/tipc/bearer.h
@@ -205,7 +205,6 @@ void tipc_disable_l2_media(struct tipc_bearer *b);
 int tipc_l2_send_msg(struct net *net, struct sk_buff *buf,
                      struct tipc_bearer *b, struct tipc_media_addr *dest);
 
-struct sk_buff *tipc_bearer_get_names(struct net *net);
 void tipc_bearer_add_dest(struct net *net, u32 bearer_id, u32 dest);
 void tipc_bearer_remove_dest(struct net *net, u32 bearer_id, u32 dest);
 struct tipc_bearer *tipc_bearer_find(struct net *net, const char *name);
diff --git a/net/tipc/config.c b/net/tipc/config.c
index 6873360cda53..52e84b0ac48a 100644
--- a/net/tipc/config.c
+++ b/net/tipc/config.c
@@ -252,9 +252,6 @@ struct sk_buff *tipc_cfg_do_cmd(struct net *net, u32 orig_node, u16 cmd,
                 rep_tlv_buf = tipc_nametbl_get(net, req_tlv_area,
                                                req_tlv_space);
                 break;
-        case TIPC_CMD_GET_BEARER_NAMES:
-                rep_tlv_buf = tipc_bearer_get_names(net);
-                break;
         case TIPC_CMD_GET_MEDIA_NAMES:
                 rep_tlv_buf = tipc_media_get_names();
                 break;
diff --git a/net/tipc/netlink_compat.c b/net/tipc/netlink_compat.c
index f752854c8b10..bd75ea290e3a 100644
--- a/net/tipc/netlink_compat.c
+++ b/net/tipc/netlink_compat.c
@@ -33,9 +33,265 @@
 
 #include "core.h"
 #include "config.h"
+#include "bearer.h"
 #include <net/genetlink.h>
 #include <linux/tipc_config.h>
 
+/* The legacy API had an artificial message length limit called
+ * ULTRA_STRING_MAX_LEN.
+ */
+#define ULTRA_STRING_MAX_LEN 32768
+
+#define TIPC_SKB_MAX TLV_SPACE(ULTRA_STRING_MAX_LEN)
+
+#define REPLY_TRUNCATED "<truncated>\n"
+
+struct tipc_nl_compat_msg {
+        u16 cmd;
+        int rep_size;
+        struct sk_buff *rep;
+        struct tlv_desc *req;
+        struct sock *dst_sk;
+};
+
+struct tipc_nl_compat_cmd_dump {
+        int (*dumpit)(struct sk_buff *, struct netlink_callback *);
+        int (*format)(struct tipc_nl_compat_msg *msg, struct nlattr **attrs);
+};
+
+static int tipc_skb_tailroom(struct sk_buff *skb)
+{
+        int tailroom;
+        int limit;
+
+        tailroom = skb_tailroom(skb);
+        limit = TIPC_SKB_MAX - skb->len;
+
+        if (tailroom < limit)
+                return tailroom;
+
+        return limit;
+}
+
+static int tipc_add_tlv(struct sk_buff *skb, u16 type, void *data, u16 len)
+{
+        struct tlv_desc *tlv = (struct tlv_desc *)skb_tail_pointer(skb);
+
+        if (tipc_skb_tailroom(skb) < TLV_SPACE(len))
+                return -EMSGSIZE;
+
+        skb_put(skb, TLV_SPACE(len));
+        tlv->tlv_type = htons(type);
+        tlv->tlv_len = htons(TLV_LENGTH(len));
+        if (len && data)
+                memcpy(TLV_DATA(tlv), data, len);
+
+        return 0;
+}
+
+static struct sk_buff *tipc_tlv_alloc(int size)
+{
+        int hdr_len;
+        struct sk_buff *buf;
+
+        size = TLV_SPACE(size);
+        hdr_len = nlmsg_total_size(GENL_HDRLEN + TIPC_GENL_HDRLEN);
+
+        buf = alloc_skb(hdr_len + size, GFP_KERNEL);
+        if (!buf)
+                return NULL;
+
+        skb_reserve(buf, hdr_len);
+
+        return buf;
+}
+
+static struct sk_buff *tipc_get_err_tlv(char *str)
+{
+        int str_len = strlen(str) + 1;
+        struct sk_buff *buf;
+
+        buf = tipc_tlv_alloc(TLV_SPACE(str_len));
+        if (buf)
+                tipc_add_tlv(buf, TIPC_TLV_ERROR_STRING, str, str_len);
+
+        return buf;
+}
+
+static int __tipc_nl_compat_dumpit(struct tipc_nl_compat_cmd_dump *cmd,
+                                   struct tipc_nl_compat_msg *msg,
+                                   struct sk_buff *arg)
+{
+        int len = 0;
+        int err;
+        struct sk_buff *buf;
+        struct nlmsghdr *nlmsg;
+        struct netlink_callback cb;
+
+        memset(&cb, 0, sizeof(cb));
+        cb.nlh = (struct nlmsghdr *)arg->data;
+        cb.skb = arg;
+
+        buf = nlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
+        if (!buf)
+                return -ENOMEM;
+
+        buf->sk = msg->dst_sk;
+
+        do {
+                int rem;
+
+                len = (*cmd->dumpit)(buf, &cb);
+
+                nlmsg_for_each_msg(nlmsg, nlmsg_hdr(buf), len, rem) {
+                        struct nlattr **attrs;
+
+                        err = tipc_nlmsg_parse(nlmsg, &attrs);
+                        if (err)
+                                goto err_out;
+
+                        err = (*cmd->format)(msg, attrs);
+                        if (err)
+                                goto err_out;
+
+                        if (tipc_skb_tailroom(msg->rep) <= 1) {
+                                err = -EMSGSIZE;
+                                goto err_out;
+                        }
+                }
+
+                skb_reset_tail_pointer(buf);
+                buf->len = 0;
+
+        } while (len);
+
+        err = 0;
+
+err_out:
+        kfree_skb(buf);
+
+        if (err == -EMSGSIZE) {
+                /* The legacy API only considered messages filling
+                 * "ULTRA_STRING_MAX_LEN" to be truncated.
+                 */
+                if ((TIPC_SKB_MAX - msg->rep->len) <= 1) {
+                        char *tail = skb_tail_pointer(msg->rep);
+
+                        if (*tail != '\0')
+                                sprintf(tail - sizeof(REPLY_TRUNCATED) - 1,
+                                        REPLY_TRUNCATED);
+                }
+
+                return 0;
+        }
+
+        return err;
+}
+
+static int tipc_nl_compat_dumpit(struct tipc_nl_compat_cmd_dump *cmd,
+                                 struct tipc_nl_compat_msg *msg)
+{
+        int err;
+        struct sk_buff *arg;
+
+        msg->rep = tipc_tlv_alloc(msg->rep_size);
+        if (!msg->rep)
+                return -ENOMEM;
+
+        arg = nlmsg_new(0, GFP_KERNEL);
+        if (!arg) {
+                kfree_skb(msg->rep);
+                return -ENOMEM;
+        }
+
+        err = __tipc_nl_compat_dumpit(cmd, msg, arg);
+        if (err)
+                kfree_skb(msg->rep);
+
+        kfree_skb(arg);
+
+        return err;
+}
+
+static int tipc_nl_compat_bearer_dump(struct tipc_nl_compat_msg *msg,
+                                      struct nlattr **attrs)
+{
+        struct nlattr *bearer[TIPC_NLA_BEARER_MAX + 1];
+
+        nla_parse_nested(bearer, TIPC_NLA_BEARER_MAX, attrs[TIPC_NLA_BEARER],
+                         NULL);
+
+        return tipc_add_tlv(msg->rep, TIPC_TLV_BEARER_NAME,
+                            nla_data(bearer[TIPC_NLA_BEARER_NAME]),
+                            nla_len(bearer[TIPC_NLA_BEARER_NAME]));
+}
+
+static int tipc_nl_compat_handle(struct tipc_nl_compat_msg *msg)
+{
+        struct tipc_nl_compat_cmd_dump dump;
+
+        memset(&dump, 0, sizeof(dump));
+
+        switch (msg->cmd) {
+        case TIPC_CMD_GET_BEARER_NAMES:
+                msg->rep_size = MAX_BEARERS * TLV_SPACE(TIPC_MAX_BEARER_NAME);
+                dump.dumpit = tipc_nl_bearer_dump;
+                dump.format = tipc_nl_compat_bearer_dump;
+                return tipc_nl_compat_dumpit(&dump, msg);
+        }
+
+        return -EOPNOTSUPP;
+}
+
+static int tipc_nl_compat_recv(struct sk_buff *skb, struct genl_info *info)
+{
+        int err;
+        int len;
+        struct tipc_nl_compat_msg msg;
+        struct nlmsghdr *req_nlh;
+        struct nlmsghdr *rep_nlh;
+        struct tipc_genlmsghdr *req_userhdr = info->userhdr;
+        struct net *net = genl_info_net(info);
+
+        memset(&msg, 0, sizeof(msg));
+
+        req_nlh = (struct nlmsghdr *)skb->data;
+        msg.req = nlmsg_data(req_nlh) + GENL_HDRLEN + TIPC_GENL_HDRLEN;
+        msg.cmd = req_userhdr->cmd;
+        msg.dst_sk = info->dst_sk;
+
+        if ((msg.cmd & 0xC000) && (!netlink_net_capable(skb, CAP_NET_ADMIN))) {
+                msg.rep = tipc_get_err_tlv(TIPC_CFG_NOT_NET_ADMIN);
+                err = -EACCES;
+                goto send;
+        }
+
+        len = nlmsg_attrlen(req_nlh, GENL_HDRLEN + TIPC_GENL_HDRLEN);
+        if (TLV_GET_LEN(msg.req) && !TLV_OK(msg.req, len)) {
+                msg.rep = tipc_get_err_tlv(TIPC_CFG_NOT_SUPPORTED);
+                err = -EOPNOTSUPP;
+                goto send;
+        }
+
+        err = tipc_nl_compat_handle(&msg);
+        if (err == -EOPNOTSUPP)
+                msg.rep = tipc_get_err_tlv(TIPC_CFG_NOT_SUPPORTED);
+        else if (err == -EINVAL)
+                msg.rep = tipc_get_err_tlv(TIPC_CFG_TLV_ERROR);
+send:
+        if (!msg.rep)
+                return err;
+
+        len = nlmsg_total_size(GENL_HDRLEN + TIPC_GENL_HDRLEN);
+        skb_push(msg.rep, len);
+        rep_nlh = nlmsg_hdr(msg.rep);
+        memcpy(rep_nlh, info->nlhdr, len);
+        rep_nlh->nlmsg_len = msg.rep->len;
+        genlmsg_unicast(net, msg.rep, NETLINK_CB(skb).portid);
+
+        return err;
+}
+
 static int handle_cmd(struct sk_buff *skb, struct genl_info *info)
 {
         struct net *net = genl_info_net(info);
@@ -69,6 +325,22 @@ static int handle_cmd(struct sk_buff *skb, struct genl_info *info)
         return 0;
 }
 
+/* Temporary function to keep functionality throughout the patchset
+ * without having to mess with the global variables and other trickery
+ * of the old API.
+ */
+static int tipc_nl_compat_tmp_wrap(struct sk_buff *skb, struct genl_info *info)
+{
+        struct tipc_genlmsghdr *req = info->userhdr;
+
+        switch (req->cmd) {
+        case TIPC_CMD_GET_BEARER_NAMES:
+                return tipc_nl_compat_recv(skb, info);
+        }
+
+        return handle_cmd(skb, info);
+}
+
 static struct genl_family tipc_genl_compat_family = {
         .id             = GENL_ID_GENERATE,
         .name           = TIPC_GENL_NAME,
@@ -81,7 +353,7 @@ static struct genl_family tipc_genl_compat_family = {
 static struct genl_ops tipc_genl_compat_ops[] = {
         {
                 .cmd            = TIPC_GENL_CMD,
-                .doit           = handle_cmd,
+                .doit           = tipc_nl_compat_tmp_wrap,
         },
 };