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>

1 files changed, 44 insertions, 8 deletions

diff --git a/net/9p/trans_rdma.c b/net/9p/trans_rdma.c
index 14ad43b5cf89..3533d2a53ab6 100644
--- 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);