sunrpc: Enable the kernel to specify the hostname part of service principals
A multi-homed NFS server may have more than one "nfs" key in its
keytab. Enable the kernel to pick the key it wants as a machine
credential when establishing a GSS context.
This is useful for GSS-protected NFSv4.0 callbacks, which are
required by RFC 7530 S3.3.3 to use the same principal as the service
principal the client used when establishing its lease.
A complementary modification to rpc.gssd is required to fully enable
this feature.
Signed-off-by: Chuck Lever <[email protected]>
Signed-off-by: J. Bruce Fields <[email protected]>
diff --git a/net/sunrpc/auth_gss/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c
index be8f103..1943e11 100644
--- a/net/sunrpc/auth_gss/auth_gss.c
+++ b/net/sunrpc/auth_gss/auth_gss.c
@@ -284,7 +284,12 @@ gss_fill_context(const void *p, const void *end, struct gss_cl_ctx *ctx, struct
return p;
}
-#define UPCALL_BUF_LEN 128
+/* XXX: Need some documentation about why UPCALL_BUF_LEN is so small.
+ * Is user space expecting no more than UPCALL_BUF_LEN bytes?
+ * Note that there are now _two_ NI_MAXHOST sized data items
+ * being passed in this string.
+ */
+#define UPCALL_BUF_LEN 256
struct gss_upcall_msg {
refcount_t count;
@@ -462,8 +467,17 @@ static int gss_encode_v1_msg(struct gss_upcall_msg *gss_msg,
p += len;
gss_msg->msg.len += len;
}
- if (service_name != NULL) {
- len = scnprintf(p, buflen, "service=%s ", service_name);
+ if (service_name) {
+ char *c = strchr(service_name, '@');
+
+ if (!c)
+ len = scnprintf(p, buflen, "service=%s ",
+ service_name);
+ else
+ len = scnprintf(p, buflen,
+ "service=%.*s srchost=%s ",
+ (int)(c - service_name),
+ service_name, c + 1);
buflen -= len;
p += len;
gss_msg->msg.len += len;
