ksmbd: add support for supplementary groups

Even though system user has a supplementary group, It gets
NT_STATUS_ACCESS_DENIED when attempting to create file or directory.
This patch add KSMBD_EVENT_LOGIN_REQUEST_EXT/RESPONSE_EXT netlink events
to get supplementary groups list. The new netlink event doesn't break
backward compatibility when using old ksmbd-tools.
Co-developed-by: Atte Heikkilä <atteh.mailbox@gmail.com>
Signed-off-by: Atte Heikkilä <atteh.mailbox@gmail.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/smb/server/auth.c

@@ -512,6 +512,7 @@ int ksmbd_krb5_authenticate(struct ksmbd_session *sess, char *in_blob,
 			    int in_len, char *out_blob, int *out_len)
 {
 	struct ksmbd_spnego_authen_response *resp;
+	struct ksmbd_login_response_ext *resp_ext = NULL;
 	struct ksmbd_user *user = NULL;
 	int retval;
 
@@ -540,7 +541,10 @@ int ksmbd_krb5_authenticate(struct ksmbd_session *sess, char *in_blob,
 		goto out;
 	}
 
-	user = ksmbd_alloc_user(&resp->login_response);
+	if (resp->login_response.status & KSMBD_USER_FLAG_EXTENSION)
+		resp_ext = ksmbd_ipc_login_request_ext(resp->login_response.account);
+
+	user = ksmbd_alloc_user(&resp->login_response, resp_ext);
 	if (!user) {
 		ksmbd_debug(AUTH, "login failure\n");
 		retval = -ENOMEM;

fs/smb/server/ksmbd_netlink.h

@@ -51,6 +51,9 @@
  *  - KSMBD_EVENT_SPNEGO_AUTHEN_REQUEST/RESPONSE(ksmbd_spnego_authen_request/response)
  *    This event is to make kerberos authentication to be processed in
  *    userspace.
+ *
+ *  - KSMBD_EVENT_LOGIN_REQUEST_EXT/RESPONSE_EXT(ksmbd_login_request_ext/response_ext)
+ *    This event is to get user account extension info to user IPC daemon.
  */
 
 #define KSMBD_GENL_NAME		"SMBD_GENL"
@@ -145,6 +148,16 @@ struct ksmbd_login_response {
 	__u32	reserved[16];			/* Reserved room */
 };
 
+/*
+ * IPC user login response extension.
+ */
+struct ksmbd_login_response_ext {
+	__u32	handle;
+	__s32	ngroups;			/* supplementary group count */
+	__s8	reserved[128];			/* Reserved room */
+	__s8	____payload[];
+};
+
 /*
  * IPC request to fetch net share config.
  */
@@ -306,6 +319,9 @@ enum ksmbd_event {
 	KSMBD_EVENT_SPNEGO_AUTHEN_REQUEST,
 	KSMBD_EVENT_SPNEGO_AUTHEN_RESPONSE	= 15,
 
+	KSMBD_EVENT_LOGIN_REQUEST_EXT,
+	KSMBD_EVENT_LOGIN_RESPONSE_EXT,
+
 	__KSMBD_EVENT_MAX,
 	KSMBD_EVENT_MAX = __KSMBD_EVENT_MAX - 1
 };
@@ -336,6 +352,7 @@ enum KSMBD_TREE_CONN_STATUS {
 #define KSMBD_USER_FLAG_BAD_USER	BIT(3)
 #define KSMBD_USER_FLAG_GUEST_ACCOUNT	BIT(4)
 #define KSMBD_USER_FLAG_DELAY_SESSION	BIT(5)
+#define KSMBD_USER_FLAG_EXTENSION	BIT(6)
 
 /*
  * Share config flags.

fs/smb/server/mgmt/user_config.c

@@ -12,6 +12,7 @@
 struct ksmbd_user *ksmbd_login_user(const char *account)
 {
 	struct ksmbd_login_response *resp;
+	struct ksmbd_login_response_ext *resp_ext = NULL;
 	struct ksmbd_user *user = NULL;
 
 	resp = ksmbd_ipc_login_request(account);
@@ -21,15 +22,19 @@ struct ksmbd_user *ksmbd_login_user(const char *account)
 	if (!(resp->status & KSMBD_USER_FLAG_OK))
 		goto out;
 
-	user = ksmbd_alloc_user(resp);
+	if (resp->status & KSMBD_USER_FLAG_EXTENSION)
+		resp_ext = ksmbd_ipc_login_request_ext(account);
+
+	user = ksmbd_alloc_user(resp, resp_ext);
 out:
 	kvfree(resp);
 	return user;
 }
 
-struct ksmbd_user *ksmbd_alloc_user(struct ksmbd_login_response *resp)
+struct ksmbd_user *ksmbd_alloc_user(struct ksmbd_login_response *resp,
+		struct ksmbd_login_response_ext *resp_ext)
 {
-	struct ksmbd_user *user = NULL;
+	struct ksmbd_user *user;
 
 	user = kmalloc(sizeof(struct ksmbd_user), GFP_KERNEL);
 	if (!user)
@@ -44,18 +49,42 @@ struct ksmbd_user *ksmbd_alloc_user(struct ksmbd_login_response *resp)
 	if (user->passkey)
 		memcpy(user->passkey, resp->hash, resp->hash_sz);
 
-	if (!user->name || !user->passkey) {
-		kfree(user->name);
-		kfree(user->passkey);
-		kfree(user);
-		user = NULL;
+	user->ngroups = 0;
+	user->sgid = NULL;
+
+	if (!user->name || !user->passkey)
+		goto err_free;
+
+	if (resp_ext) {
+		if (resp_ext->ngroups > NGROUPS_MAX) {
+			pr_err("ngroups(%u) from login response exceeds max groups(%d)\n",
+					resp_ext->ngroups, NGROUPS_MAX);
+			goto err_free;
+		}
+
+		user->sgid = kmemdup(resp_ext->____payload,
+				     resp_ext->ngroups * sizeof(gid_t),
+				     GFP_KERNEL);
+		if (!user->sgid)
+			goto err_free;
+
+		user->ngroups = resp_ext->ngroups;
+		ksmbd_debug(SMB, "supplementary groups : %d\n", user->ngroups);
 	}
+
 	return user;
+
+err_free:
+	kfree(user->name);
+	kfree(user->passkey);
+	kfree(user);
+	return NULL;
 }
 
 void ksmbd_free_user(struct ksmbd_user *user)
 {
 	ksmbd_ipc_logout_request(user->name, user->flags);
+	kfree(user->sgid);
 	kfree(user->name);
 	kfree(user->passkey);
 	kfree(user);

fs/smb/server/mgmt/user_config.h

@@ -18,6 +18,8 @@ struct ksmbd_user {
 
 	size_t			passkey_sz;
 	char			*passkey;
+	int			ngroups;
+	gid_t			*sgid;
 };
 
 static inline bool user_guest(struct ksmbd_user *user)
@@ -60,7 +62,8 @@ static inline unsigned int user_gid(struct ksmbd_user *user)
 }
 
 struct ksmbd_user *ksmbd_login_user(const char *account);
-struct ksmbd_user *ksmbd_alloc_user(struct ksmbd_login_response *resp);
+struct ksmbd_user *ksmbd_alloc_user(struct ksmbd_login_response *resp,
+		struct ksmbd_login_response_ext *resp_ext);
 void ksmbd_free_user(struct ksmbd_user *user);
 int ksmbd_anonymous_user(struct ksmbd_user *user);
 bool ksmbd_compare_user(struct ksmbd_user *u1, struct ksmbd_user *u2);

fs/smb/server/smb_common.c

@@ -736,13 +736,15 @@ int __ksmbd_override_fsids(struct ksmbd_work *work,
 		struct ksmbd_share_config *share)
 {
 	struct ksmbd_session *sess = work->sess;
+	struct ksmbd_user *user = sess->user;
 	struct cred *cred;
 	struct group_info *gi;
 	unsigned int uid;
 	unsigned int gid;
+	int i;
 
-	uid = user_uid(sess->user);
-	gid = user_gid(sess->user);
+	uid = user_uid(user);
+	gid = user_gid(user);
 	if (share->force_uid != KSMBD_SHARE_INVALID_UID)
 		uid = share->force_uid;
 	if (share->force_gid != KSMBD_SHARE_INVALID_GID)
@@ -755,11 +757,18 @@ int __ksmbd_override_fsids(struct ksmbd_work *work,
 	cred->fsuid = make_kuid(&init_user_ns, uid);
 	cred->fsgid = make_kgid(&init_user_ns, gid);
 
-	gi = groups_alloc(0);
+	gi = groups_alloc(user->ngroups);
 	if (!gi) {
 		abort_creds(cred);
 		return -ENOMEM;
 	}
+
+	for (i = 0; i < user->ngroups; i++)
+		gi->gid[i] = make_kgid(&init_user_ns, user->sgid[i]);
+
+	if (user->ngroups)
+		groups_sort(gi);
+
 	set_groups(cred, gi);
 	put_group_info(gi);
 

fs/smb/server/transport_ipc.c

@@ -120,6 +120,12 @@ static const struct nla_policy ksmbd_nl_policy[KSMBD_EVENT_MAX + 1] = {
 	},
 	[KSMBD_EVENT_SPNEGO_AUTHEN_RESPONSE] = {
 	},
+	[KSMBD_EVENT_LOGIN_REQUEST_EXT] = {
+		.len = sizeof(struct ksmbd_login_request),
+	},
+	[KSMBD_EVENT_LOGIN_RESPONSE_EXT] = {
+		.len = sizeof(struct ksmbd_login_response_ext),
+	},
 };
 
 static struct genl_ops ksmbd_genl_ops[] = {
@@ -187,6 +193,14 @@ static struct genl_ops ksmbd_genl_ops[] = {
 		.cmd	= KSMBD_EVENT_SPNEGO_AUTHEN_RESPONSE,
 		.doit	= handle_generic_event,
 	},
+	{
+		.cmd	= KSMBD_EVENT_LOGIN_REQUEST_EXT,
+		.doit	= handle_unsupported_event,
+	},
+	{
+		.cmd	= KSMBD_EVENT_LOGIN_RESPONSE_EXT,
+		.doit	= handle_generic_event,
+	},
 };
 
 static struct genl_family ksmbd_genl_family = {
@@ -198,7 +212,7 @@ static struct genl_family ksmbd_genl_family = {
 	.module		= THIS_MODULE,
 	.ops		= ksmbd_genl_ops,
 	.n_ops		= ARRAY_SIZE(ksmbd_genl_ops),
-	.resv_start_op	= KSMBD_EVENT_SPNEGO_AUTHEN_RESPONSE + 1,
+	.resv_start_op	= KSMBD_EVENT_LOGIN_RESPONSE_EXT + 1,
 };
 
 static void ksmbd_nl_init_fixup(void)
@@ -459,16 +473,24 @@ static int ipc_validate_msg(struct ipc_msg_table_entry *entry)
 {
 	unsigned int msg_sz = entry->msg_sz;
 
-	if (entry->type == KSMBD_EVENT_RPC_REQUEST) {
+	switch (entry->type) {
+	case KSMBD_EVENT_RPC_REQUEST:
+	{
 		struct ksmbd_rpc_command *resp = entry->response;
 
 		msg_sz = sizeof(struct ksmbd_rpc_command) + resp->payload_sz;
-	} else if (entry->type == KSMBD_EVENT_SPNEGO_AUTHEN_REQUEST) {
+		break;
+	}
+	case KSMBD_EVENT_SPNEGO_AUTHEN_REQUEST:
+	{
 		struct ksmbd_spnego_authen_response *resp = entry->response;
 
 		msg_sz = sizeof(struct ksmbd_spnego_authen_response) +
 				resp->session_key_len + resp->spnego_blob_len;
-	} else if (entry->type == KSMBD_EVENT_SHARE_CONFIG_REQUEST) {
+		break;
+	}
+	case KSMBD_EVENT_SHARE_CONFIG_REQUEST:
+	{
 		struct ksmbd_share_config_response *resp = entry->response;
 
 		if (resp->payload_sz) {
@@ -478,6 +500,17 @@ static int ipc_validate_msg(struct ipc_msg_table_entry *entry)
 			msg_sz = sizeof(struct ksmbd_share_config_response) +
 					resp->payload_sz;
 		}
+		break;
+	}
+	case KSMBD_EVENT_LOGIN_REQUEST_EXT:
+	{
+		struct ksmbd_login_response_ext *resp = entry->response;
+
+		if (resp->ngroups) {
+			msg_sz = sizeof(struct ksmbd_login_response_ext) +
+					resp->ngroups * sizeof(gid_t);
+		}
+	}
 	}
 
 	return entry->msg_sz != msg_sz ? -EINVAL : 0;
@@ -560,6 +593,29 @@ struct ksmbd_login_response *ksmbd_ipc_login_request(const char *account)
 	return resp;
 }
 
+struct ksmbd_login_response_ext *ksmbd_ipc_login_request_ext(const char *account)
+{
+	struct ksmbd_ipc_msg *msg;
+	struct ksmbd_login_request *req;
+	struct ksmbd_login_response_ext *resp;
+
+	if (strlen(account) >= KSMBD_REQ_MAX_ACCOUNT_NAME_SZ)
+		return NULL;
+
+	msg = ipc_msg_alloc(sizeof(struct ksmbd_login_request));
+	if (!msg)
+		return NULL;
+
+	msg->type = KSMBD_EVENT_LOGIN_REQUEST_EXT;
+	req = (struct ksmbd_login_request *)msg->payload;
+	req->handle = ksmbd_acquire_id(&ipc_ida);
+	strscpy(req->account, account, KSMBD_REQ_MAX_ACCOUNT_NAME_SZ);
+	resp = ipc_msg_send_request(msg, req->handle);
+	ipc_msg_handle_free(req->handle);
+	ipc_msg_free(msg);
+	return resp;
+}
+
 struct ksmbd_spnego_authen_response *
 ksmbd_ipc_spnego_authen_request(const char *spnego_blob, int blob_len)
 {

fs/smb/server/transport_ipc.h

@@ -12,6 +12,8 @@
 
 struct ksmbd_login_response *
 ksmbd_ipc_login_request(const char *account);
+struct ksmbd_login_response_ext *
+ksmbd_ipc_login_request_ext(const char *account);
 
 struct ksmbd_session;
 struct ksmbd_share_config;