iscsi-target: Fix CHAP_A parameter list handling

The target is failing to handle list of CHAP_A key-value pair form
initiator.The target is expecting CHAP_A=5 always. In other cases,
where initiator sends list (for example) CHAP_A=6,5 target is failing
the security negotiation. Which is incorrect.

This patch handles the case (RFC 3720 section 11.1.4).
where in the initiator may send list of CHAP_A values and target replies
with appropriate CHAP_A value in response

(Drop whitespaces + rename to chap_check_algorithm + save original
 pointer + add explicit check for CHAP_A key - nab)

Signed-off-by: Tejas Vaykole <tejas.vaykole@calsoftinc.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

diff --git a/drivers/target/iscsi/iscsi_target_auth.c b/drivers/target/iscsi/iscsi_target_auth.c
index de77d9aa22c6329b41d515a157e49d54451edf50..155f33848aa623ecbc3ad48468b62f5c09cf664d 100644 (file)
--- a/drivers/target/iscsi/iscsi_target_auth.c
+++ b/drivers/target/iscsi/iscsi_target_auth.c
@@ -71,6 +71,40 @@ static void chap_gen_challenge(
                        challenge_asciihex);
 }
 
+static int chap_check_algorithm(const char *a_str)
+{
+       char *tmp, *orig, *token;
+
+       tmp = kstrdup(a_str, GFP_KERNEL);
+       if (!tmp) {
+               pr_err("Memory allocation failed for CHAP_A temporary buffer\n");
+               return CHAP_DIGEST_UNKNOWN;
+       }
+       orig = tmp;
+
+       token = strsep(&tmp, "=");
+       if (!token)
+               goto out;
+
+       if (strcmp(token, "CHAP_A")) {
+               pr_err("Unable to locate CHAP_A key\n");
+               goto out;
+       }
+       while (token) {
+               token = strsep(&tmp, ",");
+               if (!token)
+                       goto out;
+
+               if (!strncmp(token, "5", 1)) {
+                       pr_debug("Selected MD5 Algorithm\n");
+                       kfree(orig);
+                       return CHAP_DIGEST_MD5;
+               }
+       }
+out:
+       kfree(orig);
+       return CHAP_DIGEST_UNKNOWN;
+}
 
 static struct iscsi_chap *chap_server_open(
        struct iscsi_conn *conn,
@@ -79,6 +113,7 @@ static struct iscsi_chap *chap_server_open(
        char *aic_str,
        unsigned int *aic_len)
 {
+       int ret;
        struct iscsi_chap *chap;
 
        if (!(auth->naf_flags & NAF_USERID_SET) ||
@@ -93,21 +128,24 @@ static struct iscsi_chap *chap_server_open(
                return NULL;
 
        chap = conn->auth_protocol;
-       /*
-        * We only support MD5 MDA presently.
-        */
-       if (strncmp(a_str, "CHAP_A=5", 8)) {
-               pr_err("CHAP_A is not MD5.\n");
+       ret = chap_check_algorithm(a_str);
+       switch (ret) {
+       case CHAP_DIGEST_MD5:
+               pr_debug("[server] Got CHAP_A=5\n");
+               /*
+                * Send back CHAP_A set to MD5.
+               */
+               *aic_len = sprintf(aic_str, "CHAP_A=5");
+               *aic_len += 1;
+               chap->digest_type = CHAP_DIGEST_MD5;
+               pr_debug("[server] Sending CHAP_A=%d\n", chap->digest_type);
+               break;
+       case CHAP_DIGEST_UNKNOWN:
+       default:
+               pr_err("Unsupported CHAP_A value\n");
                return NULL;
        }
-       pr_debug("[server] Got CHAP_A=5\n");
-       /*
-        * Send back CHAP_A set to MD5.
-        */
-       *aic_len = sprintf(aic_str, "CHAP_A=5");
-       *aic_len += 1;
-       chap->digest_type = CHAP_DIGEST_MD5;
-       pr_debug("[server] Sending CHAP_A=%d\n", chap->digest_type);
+
        /*
         * Set Identifier.
         */

diff --git a/drivers/target/iscsi/iscsi_target_auth.h b/drivers/target/iscsi/iscsi_target_auth.h
index 2f463c09626d9232df18fd391daf716440ee543a..d22f7b96a06ca98aa3bd83f669d92eb686cfcec9 100644 (file)
--- a/drivers/target/iscsi/iscsi_target_auth.h
+++ b/drivers/target/iscsi/iscsi_target_auth.h
@@ -1,6 +1,7 @@
 #ifndef _ISCSI_CHAP_H_
 #define _ISCSI_CHAP_H_
 
+#define CHAP_DIGEST_UNKNOWN    0
 #define CHAP_DIGEST_MD5                5
 #define CHAP_DIGEST_SHA                6