[CIFS] clean up upcall handling for dns_resolver keys

We're given the datalen in the downcall, so there's no need to do any
calls to strlen(). Just keep track of the datalen in the key. Finally,
add a sanity check of the data in the downcall to make sure that it
looks like a real IP address.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

1 files changed, 41 insertions, 33 deletions

diff --git a/fs/cifs/dns_resolve.c b/fs/cifs/dns_resolve.c
index a2e0673e1b08..1e0c1bd8f2e4 100644
--- a/fs/cifs/dns_resolve.c
+++ b/fs/cifs/dns_resolve.c
@@ -29,19 +29,55 @@
 #include "cifsproto.h"
 #include "cifs_debug.h"
 
-static int dns_resolver_instantiate(struct key *key, const void *data,
+/* Checks if supplied name is IP address
+ * returns:
+ *              1 - name is IP
+ *              0 - name is not IP
+ */
+static int
+is_ip(const char *name)
+{
+        int rc;
+        struct sockaddr_in sin_server;
+        struct sockaddr_in6 sin_server6;
+
+        rc = cifs_inet_pton(AF_INET, name,
+                        &sin_server.sin_addr.s_addr);
+
+        if (rc <= 0) {
+                /* not ipv4 address, try ipv6 */
+                rc = cifs_inet_pton(AF_INET6, name,
+                                &sin_server6.sin6_addr.in6_u);
+                if (rc > 0)
+                        return 1;
+        } else {
+                return 1;
+        }
+        /* we failed translating address */
+        return 0;
+}
+
+static int
+dns_resolver_instantiate(struct key *key, const void *data,
                 size_t datalen)
 {
         int rc = 0;
         char *ip;
 
-        ip = kmalloc(datalen+1, GFP_KERNEL);
+        ip = kmalloc(datalen + 1, GFP_KERNEL);
         if (!ip)
                 return -ENOMEM;
 
         memcpy(ip, data, datalen);
         ip[datalen] = '\0';
 
+        /* make sure this looks like an address */
+        if (!is_ip((const char *) ip)) {
+                kfree(ip);
+                return -EINVAL;
+        }
+
+        key->type_data.x[0] = datalen;
         rcu_assign_pointer(key->payload.data, ip);
 
         return rc;
@@ -62,33 +98,6 @@ struct key_type key_type_dns_resolver = {
         .match       = user_match,
 };
 
-/* Checks if supplied name is IP address
- * returns:
- *              1 - name is IP
- *              0 - name is not IP
- */
-static int is_ip(const char *name)
-{
-        int rc;
-        struct sockaddr_in sin_server;
-        struct sockaddr_in6 sin_server6;
-
-        rc = cifs_inet_pton(AF_INET, name,
-                        &sin_server.sin_addr.s_addr);
-
-        if (rc <= 0) {
-                /* not ipv4 address, try ipv6 */
-                rc = cifs_inet_pton(AF_INET6, name,
-                                &sin_server6.sin6_addr.in6_u);
-                if (rc > 0)
-                        return 1;
-        } else {
-                return 1;
-        }
-        /* we failed translating address */
-        return 0;
-}
-
 /* Resolves server name to ip address.
  * input:
  *      unc - server UNC
@@ -140,6 +149,7 @@ dns_resolve_server_name_to_ip(const char *unc, char **ip_addr)
 
         rkey = request_key(&key_type_dns_resolver, name, "");
         if (!IS_ERR(rkey)) {
+                len = rkey->type_data.x[0];
                 data = rkey->payload.data;
         } else {
                 cERROR(1, ("%s: unable to resolve: %s", __func__, name));
@@ -148,11 +158,9 @@ dns_resolve_server_name_to_ip(const char *unc, char **ip_addr)
 
 skip_upcall:
         if (data) {
-                len = strlen(data);
-                *ip_addr = kmalloc(len+1, GFP_KERNEL);
+                *ip_addr = kmalloc(len + 1, GFP_KERNEL);
                 if (*ip_addr) {
-                        memcpy(*ip_addr, data, len);
-                        (*ip_addr)[len] = '\0';
+                        memcpy(*ip_addr, data, len + 1);
                         if (!IS_ERR(rkey))
                                 cFYI(1, ("%s: resolved: %s to %s", __func__,
                                                         name,