scsi: target: iscsi: Do not require target authentication

RFC7143 states that Initiator decides what type of authentication to
use:

The initiator MUST continue with:
    CHAP_N=<N> CHAP_R=<R>
or, if it requires target authentication, with:
    CHAP_N=<N> CHAP_R=<R> CHAP_I=<I> CHAP_C=<C>

Allow one way authentication if mutual authentication is configured.  That
passes some tests from Windows HLK for Mutual CHAP with iSNS.

Link: https://lore.kernel.org/r/20220718152555.17084-5-d.bogdanov@yadro.com
Reviewed-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Dmitry Bogdanov <d.bogdanov@yadro.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Author: logost

drivers/target/iscsi/iscsi_target_auth.c

@@ -416,7 +416,13 @@ static int chap_server_compute_hash(
 	/*
 	 * Get CHAP_I.
 	 */
-	if (extract_param(nr_in_ptr, "CHAP_I", 10, identifier, &type) < 0) {
+	ret = extract_param(nr_in_ptr, "CHAP_I", 10, identifier, &type);
+	if (ret == -ENOENT) {
+		pr_debug("Could not find CHAP_I. Initiator uses One way authentication.\n");
+		auth_ret = 0;
+		goto out;
+	}
+	if (ret < 0) {
 		pr_err("Could not find CHAP_I.\n");
 		goto out;
 	}

drivers/target/iscsi/iscsi_target_nego.c

@@ -62,15 +62,15 @@ int extract_param(
 	int len;
 
 	if (!in_buf || !pattern || !out_buf || !type)
-		return -1;
+		return -EINVAL;
 
 	ptr = strstr(in_buf, pattern);
 	if (!ptr)
-		return -1;
+		return -ENOENT;
 
 	ptr = strstr(ptr, "=");
 	if (!ptr)
-		return -1;
+		return -EINVAL;
 
 	ptr += 1;
 	if (*ptr == '0' && (*(ptr+1) == 'x' || *(ptr+1) == 'X')) {
@@ -84,12 +84,12 @@ int extract_param(
 
 	len = strlen_semi(ptr);
 	if (len < 0)
-		return -1;
+		return -EINVAL;
 
 	if (len >= max_length) {
 		pr_err("Length of input: %d exceeds max_length:"
 			" %d\n", len, max_length);
-		return -1;
+		return -EINVAL;
 	}
 	memcpy(out_buf, ptr, len);
 	out_buf[len] = '\0';