1 files changed, 236 insertions, 0 deletions
diff --git a/fs/smb/client/cifs_spnego.c b/fs/smb/client/cifs_spnego.c
new file mode 100644
index 000000000000..6f3285f1dfee
--- /dev/null
+++ b/fs/smb/client/cifs_spnego.c
@@ -0,0 +1,236 @@
+// SPDX-License-Identifier: LGPL-2.1
+/*
+ *   SPNEGO upcall management for CIFS
+ *
+ *   Copyright (c) 2007 Red Hat, Inc.
+ *   Author(s): Jeff Layton (jlayton@redhat.com)
+ *
+ */
+
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <keys/user-type.h>
+#include <linux/key-type.h>
+#include <linux/keyctl.h>
+#include <linux/inet.h>
+#include "cifsglob.h"
+#include "cifs_spnego.h"
+#include "cifs_debug.h"
+#include "cifsproto.h"
+static const struct cred *spnego_cred;
+
+/* create a new cifs key */
+static int
+cifs_spnego_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
+{
+	char *payload;
+	int ret;
+
+	ret = -ENOMEM;
+	payload = kmemdup(prep->data, prep->datalen, GFP_KERNEL);
+	if (!payload)
+		goto error;
+
+	/* attach the data */
+	key->payload.data[0] = payload;
+	ret = 0;
+
+error:
+	return ret;
+}
+
+static void
+cifs_spnego_key_destroy(struct key *key)
+{
+	kfree(key->payload.data[0]);
+}
+
+
+/*
+ * keytype for CIFS spnego keys
+ */
+struct key_type cifs_spnego_key_type = {
+	.name		= "cifs.spnego",
+	.instantiate	= cifs_spnego_key_instantiate,
+	.destroy	= cifs_spnego_key_destroy,
+	.describe	= user_describe,
+};
+
+/* length of longest version string e.g.  strlen("ver=0xFF") */
+#define MAX_VER_STR_LEN		8
+
+/* length of longest security mechanism name, eg in future could have
+ * strlen(";sec=ntlmsspi") */
+#define MAX_MECH_STR_LEN	13
+
+/* strlen of "host=" */
+#define HOST_KEY_LEN		5
+
+/* strlen of ";ip4=" or ";ip6=" */
+#define IP_KEY_LEN		5
+
+/* strlen of ";uid=0x" */
+#define UID_KEY_LEN		7
+
+/* strlen of ";creduid=0x" */
+#define CREDUID_KEY_LEN		11
+
+/* strlen of ";user=" */
+#define USER_KEY_LEN		6
+
+/* strlen of ";pid=0x" */
+#define PID_KEY_LEN		7
+
+/* get a key struct with a SPNEGO security blob, suitable for session setup */
+struct key *
+cifs_get_spnego_key(struct cifs_ses *sesInfo,
+		    struct TCP_Server_Info *server)
+{
+	struct sockaddr_in *sa = (struct sockaddr_in *) &server->dstaddr;
+	struct sockaddr_in6 *sa6 = (struct sockaddr_in6 *) &server->dstaddr;
+	char *description, *dp;
+	size_t desc_len;
+	struct key *spnego_key;
+	const char *hostname = server->hostname;
+	const struct cred *saved_cred;
+
+	/* length of fields (with semicolons): ver=0xyz ip4=ipaddress
+	   host=hostname sec=mechanism uid=0xFF user=username */
+	desc_len = MAX_VER_STR_LEN +
+		   HOST_KEY_LEN + strlen(hostname) +
+		   IP_KEY_LEN + INET6_ADDRSTRLEN +
+		   MAX_MECH_STR_LEN +
+		   UID_KEY_LEN + (sizeof(uid_t) * 2) +
+		   CREDUID_KEY_LEN + (sizeof(uid_t) * 2) +
+		   PID_KEY_LEN + (sizeof(pid_t) * 2) + 1;
+
+	if (sesInfo->user_name)
+		desc_len += USER_KEY_LEN + strlen(sesInfo->user_name);
+
+	spnego_key = ERR_PTR(-ENOMEM);
+	description = kzalloc(desc_len, GFP_KERNEL);
+	if (description == NULL)
+		goto out;
+
+	dp = description;
+	/* start with version and hostname portion of UNC string */
+	spnego_key = ERR_PTR(-EINVAL);
+	sprintf(dp, "ver=0x%x;host=%s;", CIFS_SPNEGO_UPCALL_VERSION,
+		hostname);
+	dp = description + strlen(description);
+
+	/* add the server address */
+	if (server->dstaddr.ss_family == AF_INET)
+		sprintf(dp, "ip4=%pI4", &sa->sin_addr);
+	else if (server->dstaddr.ss_family == AF_INET6)
+		sprintf(dp, "ip6=%pI6", &sa6->sin6_addr);
+	else
+		goto out;
+
+	dp = description + strlen(description);
+
+	/* for now, only sec=krb5 and sec=mskrb5 are valid */
+	if (server->sec_kerberos)
+		sprintf(dp, ";sec=krb5");
+	else if (server->sec_mskerberos)
+		sprintf(dp, ";sec=mskrb5");
+	else {
+		cifs_dbg(VFS, "unknown or missing server auth type, use krb5\n");
+		sprintf(dp, ";sec=krb5");
+	}
+
+	dp = description + strlen(description);
+	sprintf(dp, ";uid=0x%x",
+		from_kuid_munged(&init_user_ns, sesInfo->linux_uid));
+
+	dp = description + strlen(description);
+	sprintf(dp, ";creduid=0x%x",
+		from_kuid_munged(&init_user_ns, sesInfo->cred_uid));
+
+	if (sesInfo->user_name) {
+		dp = description + strlen(description);
+		sprintf(dp, ";user=%s", sesInfo->user_name);
+	}
+
+	dp = description + strlen(description);
+	sprintf(dp, ";pid=0x%x", current->pid);
+
+	cifs_dbg(FYI, "key description = %s\n", description);
+	saved_cred = override_creds(spnego_cred);
+	spnego_key = request_key(&cifs_spnego_key_type, description, "");
+	revert_creds(saved_cred);
+
+#ifdef CONFIG_CIFS_DEBUG2
+	if (cifsFYI && !IS_ERR(spnego_key)) {
+		struct cifs_spnego_msg *msg = spnego_key->payload.data[0];
+		cifs_dump_mem("SPNEGO reply blob:", msg->data, min(1024U,
+				msg->secblob_len + msg->sesskey_len));
+	}
+#endif /* CONFIG_CIFS_DEBUG2 */
+
+out:
+	kfree(description);
+	return spnego_key;
+}
+
+int
+init_cifs_spnego(void)
+{
+	struct cred *cred;
+	struct key *keyring;
+	int ret;
+
+	cifs_dbg(FYI, "Registering the %s key type\n",
+		 cifs_spnego_key_type.name);
+
+	/*
+	 * Create an override credential set with special thread keyring for
+	 * spnego upcalls.
+	 */
+
+	cred = prepare_kernel_cred(&init_task);
+	if (!cred)
+		return -ENOMEM;
+
+	keyring = keyring_alloc(".cifs_spnego",
+				GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, cred,
+				(KEY_POS_ALL & ~KEY_POS_SETATTR) |
+				KEY_USR_VIEW | KEY_USR_READ,
+				KEY_ALLOC_NOT_IN_QUOTA, NULL, NULL);
+	if (IS_ERR(keyring)) {
+		ret = PTR_ERR(keyring);
+		goto failed_put_cred;
+	}
+
+	ret = register_key_type(&cifs_spnego_key_type);
+	if (ret < 0)
+		goto failed_put_key;
+
+	/*
+	 * instruct request_key() to use this special keyring as a cache for
+	 * the results it looks up
+	 */
+	set_bit(KEY_FLAG_ROOT_CAN_CLEAR, &keyring->flags);
+	cred->thread_keyring = keyring;
+	cred->jit_keyring = KEY_REQKEY_DEFL_THREAD_KEYRING;
+	spnego_cred = cred;
+
+	cifs_dbg(FYI, "cifs spnego keyring: %d\n", key_serial(keyring));
+	return 0;
+
+failed_put_key:
+	key_put(keyring);
+failed_put_cred:
+	put_cred(cred);
+	return ret;
+}
+
+void
+exit_cifs_spnego(void)
+{
+	key_revoke(spnego_cred->thread_keyring);
+	unregister_key_type(&cifs_spnego_key_type);
+	put_cred(spnego_cred);
+	cifs_dbg(FYI, "Unregistered %s key type\n", cifs_spnego_key_type.name);
+}