net/9p: add a privport option for RDMA transport.

RDMA can use the same kind of weak security as TCP by checking the
client can bind to a privileged port, which is better than nothing
if TAUTH isn't implemented.

Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>
Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>

diff --git a/net/9p/trans_rdma.c b/net/9p/trans_rdma.c
index 14ad43b..3533d2a 100644 (file)
--- a/net/9p/trans_rdma.c
+++ b/net/9p/trans_rdma.c
@@ -139,6 +139,7 @@ struct p9_rdma_opts {
        int sq_depth;
        int rq_depth;
        long timeout;
+       int privport;
 };
 
 /*
@@ -146,7 +147,10 @@ struct p9_rdma_opts {
  */
 enum {
        /* Options that take integer arguments */
-       Opt_port, Opt_rq_depth, Opt_sq_depth, Opt_timeout, Opt_err,
+       Opt_port, Opt_rq_depth, Opt_sq_depth, Opt_timeout,
+       /* Options that take no argument */
+       Opt_privport,
+       Opt_err,
 };
 
 static match_table_t tokens = {
@@ -154,6 +158,7 @@ static match_table_t tokens = {
        {Opt_sq_depth, "sq=%u"},
        {Opt_rq_depth, "rq=%u"},
        {Opt_timeout, "timeout=%u"},
+       {Opt_privport, "privport"},
        {Opt_err, NULL},
 };
 
@@ -175,6 +180,7 @@ static int parse_opts(char *params, struct p9_rdma_opts *opts)
        opts->sq_depth = P9_RDMA_SQ_DEPTH;
        opts->rq_depth = P9_RDMA_RQ_DEPTH;
        opts->timeout = P9_RDMA_TIMEOUT;
+       opts->privport = 0;
 
        if (!params)
                return 0;
@@ -193,13 +199,13 @@ static int parse_opts(char *params, struct p9_rdma_opts *opts)
                if (!*p)
                        continue;
                token = match_token(p, tokens, args);
-               if (token == Opt_err)
-                       continue;
-               r = match_int(&args[0], &option);
-               if (r < 0) {
-                       p9_debug(P9_DEBUG_ERROR,
-                                "integer field, but no integer?\n");
-                       continue;
+               if ((token != Opt_err) && (token != Opt_privport)) {
+                       r = match_int(&args[0], &option);
+                       if (r < 0) {
+                               p9_debug(P9_DEBUG_ERROR,
+                                        "integer field, but no integer?\n");
+                               continue;
+                       }
                }
                switch (token) {
                case Opt_port:
@@ -214,6 +220,9 @@ static int parse_opts(char *params, struct p9_rdma_opts *opts)
                case Opt_timeout:
                        opts->timeout = option;
                        break;
+               case Opt_privport:
+                       opts->privport = 1;
+                       break;
                default:
                        continue;
                }
@@ -607,6 +616,23 @@ static int rdma_cancelled(struct p9_client *client, struct p9_req_t *req)
        return 0;
 }
 
+static int p9_rdma_bind_privport(struct p9_trans_rdma *rdma)
+{
+       struct sockaddr_in cl = {
+               .sin_family = AF_INET,
+               .sin_addr.s_addr = htonl(INADDR_ANY),
+       };
+       int port, err = -EINVAL;
+
+       for (port = P9_DEF_MAX_RESVPORT; port >= P9_DEF_MIN_RESVPORT; port--) {
+               cl.sin_port = htons((ushort)port);
+               err = rdma_bind_addr(rdma->cm_id, (struct sockaddr *)&cl);
+               if (err != -EADDRINUSE)
+                       break;
+       }
+       return err;
+}
+
 /**
  * trans_create_rdma - Transport method for creating atransport instance
  * @client: client instance
@@ -642,6 +668,16 @@ rdma_create_trans(struct p9_client *client, const char *addr, char *args)
        /* Associate the client with the transport */
        client->trans = rdma;
 
+       /* Bind to a privileged port if we need to */
+       if (opts.privport) {
+               err = p9_rdma_bind_privport(rdma);
+               if (err < 0) {
+                       pr_err("%s (%d): problem binding to privport: %d\n",
+                              __func__, task_pid_nr(current), -err);
+                       goto error;
+               }
+       }
+
        /* Resolve the server's address */
        rdma->addr.sin_family = AF_INET;
        rdma->addr.sin_addr.s_addr = in_aton(addr);