From: Chuck Lever <chuck.lever@oracle.com>
Date: Mon, 20 Aug 2018 14:39:16 +0000 (-0400)
Subject: sunrpc: Add comment defining gssd upcall API keywords
X-Git-Tag: Ubuntu-5.10.0-12.13~7135^2
X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=108b833cde9c9b93204e6a4e455829a67f9785c3;p=mirror_ubuntu-hirsute-kernel.git

sunrpc: Add comment defining gssd upcall API keywords

During review, it was found that the target, service, and srchost
keywords are easily conflated. Add an explainer.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
---

diff --git a/net/sunrpc/auth_gss/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c
index 1943e1198804..246075960712 100644
--- a/net/sunrpc/auth_gss/auth_gss.c
+++ b/net/sunrpc/auth_gss/auth_gss.c
@@ -461,12 +461,28 @@ static int gss_encode_v1_msg(struct gss_upcall_msg *gss_msg,
 	buflen -= len;
 	p += len;
 	gss_msg->msg.len = len;
+
+	/*
+	 * target= is a full service principal that names the remote
+	 * identity that we are authenticating to.
+	 */
 	if (target_name) {
 		len = scnprintf(p, buflen, "target=%s ", target_name);
 		buflen -= len;
 		p += len;
 		gss_msg->msg.len += len;
 	}
+
+	/*
+	 * gssd uses service= and srchost= to select a matching key from
+	 * the system's keytab to use as the source principal.
+	 *
+	 * service= is the service name part of the source principal,
+	 * or "*" (meaning choose any).
+	 *
+	 * srchost= is the hostname part of the source principal. When
+	 * not provided, gssd uses the local hostname.
+	 */
 	if (service_name) {
 		char *c = strchr(service_name, '@');
 
@@ -482,6 +498,7 @@ static int gss_encode_v1_msg(struct gss_upcall_msg *gss_msg,
 		p += len;
 		gss_msg->msg.len += len;
 	}
+
 	if (mech->gm_upcall_enctypes) {
 		len = scnprintf(p, buflen, "enctypes=%s ",
 				mech->gm_upcall_enctypes);