[PATCH nvme-7.3 v2 4/4] nvme-fabrics: add helper for DH-CHAP secret options

From: Xu Rao <[email protected]>

The dhchap_secret and dhchap_ctrl_secret options have a distinct string
lifetime because their values are authentication material.  The temporary
string must be checked for the DHHC-1 representation and discarded with
kfree_sensitive() when validation fails before ownership is transferred.

Add nvmf_parse_dhchap_secret() to keep match_strdup(), DHHC-1 validation,
failure cleanup, replacement of the old value and successful ownership
transfer in one scope.  Both secret options use the same helper because
their parsing and ownership rules are identical.

Keep the existing replacement semantics for an already stored valid secret;
this patch only moves the parsing and temporary allocation lifetime into
the helper.

No functional change is intended.

Suggested-by: Christoph Hellwig <[email protected]>
Reviewed-by: Sagi Grimberg <[email protected]>
Signed-off-by: Xu Rao <[email protected]>
---
 drivers/nvme/host/fabrics.c | 48 ++++++++++++++++++-------------------
 1 file changed, 24 insertions(+), 24 deletions(-)

diff --git a/drivers/nvme/host/fabrics.c b/drivers/nvme/host/fabrics.c
index 24385e777307..dc8883d85f45 100644
--- a/drivers/nvme/host/fabrics.c
+++ b/drivers/nvme/host/fabrics.c
@@ -725,6 +725,25 @@ static int nvmf_parse_string_option(substring_t *args, char **dst)
 	return 0;
 }
 
+static int nvmf_parse_dhchap_secret(substring_t *args, char **secret)
+{
+	char *value;
+
+	value = match_strdup(args);
+	if (!value)
+		return -ENOMEM;
+
+	if (strlen(value) < 11 || strncmp(value, "DHHC-1:", 7)) {
+		pr_err("Invalid DH-CHAP secret %s\n", value);
+		kfree_sensitive(value);
+		return -EINVAL;
+	}
+
+	kfree(*secret);
+	*secret = value;
+	return 0;
+}
+
 static int nvmf_parse_options(struct nvmf_ctrl_options *opts,
 		const char *buf)
 {
@@ -1010,34 +1029,15 @@ static int nvmf_parse_options(struct nvmf_ctrl_options *opts,
 			opts->discovery_nqn = true;
 			break;
 		case NVMF_OPT_DHCHAP_SECRET:
-			p = match_strdup(args);
-			if (!p) {
-				ret = -ENOMEM;
-				goto out;
-			}
-			if (strlen(p) < 11 || strncmp(p, "DHHC-1:", 7)) {
-				pr_err("Invalid DH-CHAP secret %s\n", p);
-				kfree_sensitive(p);
-				ret = -EINVAL;
+			ret = nvmf_parse_dhchap_secret(args, &opts->dhchap_secret);
+			if (ret)
 				goto out;
-			}
-			kfree(opts->dhchap_secret);
-			opts->dhchap_secret = p;
 			break;
 		case NVMF_OPT_DHCHAP_CTRL_SECRET:
-			p = match_strdup(args);
-			if (!p) {
-				ret = -ENOMEM;
-				goto out;
-			}
-			if (strlen(p) < 11 || strncmp(p, "DHHC-1:", 7)) {
-				pr_err("Invalid DH-CHAP secret %s\n", p);
-				kfree_sensitive(p);
-				ret = -EINVAL;
+			ret = nvmf_parse_dhchap_secret(args,
+						       &opts->dhchap_ctrl_secret);
+			if (ret)
 				goto out;
-			}
-			kfree(opts->dhchap_ctrl_secret);
-			opts->dhchap_ctrl_secret = p;
 			break;
 		case NVMF_OPT_TLS:
 			if (!IS_ENABLED(CONFIG_NVME_TCP_TLS)) {
-- 
2.50.1