text: // SPDX-License-Identifier: GPL-2.0+
  /*
   *  linux/net/sunrpc/gss_rpc_upcall.c
   *
   *  Copyright (C) 2012 Simo Sorce <simo@redhat.com>
   */
  
  #include <linux/types.h>
  #include <linux/un.h>
  
  #include <linux/sunrpc/svcauth.h>
  #include "gss_rpc_upcall.h"
  
  #define GSSPROXY_SOCK_PATHNAME	"/var/run/gssproxy.sock"
  
  #define GSSPROXY_PROGRAM	(400112u)
  #define GSSPROXY_VERS_1		(1u)
  
  /*
   * Encoding/Decoding functions
   */
  
  enum {
  	GSSX_NULL = 0,	/* Unused */
          GSSX_INDICATE_MECHS = 1,
          GSSX_GET_CALL_CONTEXT = 2,
          GSSX_IMPORT_AND_CANON_NAME = 3,
          GSSX_EXPORT_CRED = 4,
          GSSX_IMPORT_CRED = 5,
          GSSX_ACQUIRE_CRED = 6,
          GSSX_STORE_CRED = 7,
          GSSX_INIT_SEC_CONTEXT = 8,
          GSSX_ACCEPT_SEC_CONTEXT = 9,
          GSSX_RELEASE_HANDLE = 10,
          GSSX_GET_MIC = 11,
          GSSX_VERIFY = 12,
          GSSX_WRAP = 13,
          GSSX_UNWRAP = 14,
          GSSX_WRAP_SIZE_LIMIT = 15,
  };
  
  #define PROC(proc, name)				\
  [GSSX_##proc] = {					\
  	.p_proc   = GSSX_##proc,			\
  	.p_encode = gssx_enc_##name,	\
  	.p_decode = gssx_dec_##name,	\
  	.p_arglen = GSSX_ARG_##name##_sz,		\
  	.p_replen = GSSX_RES_##name##_sz, 		\
  	.p_statidx = GSSX_##proc,			\
  	.p_name   = #proc,				\
  }
  
  static const struct rpc_procinfo gssp_procedures[] = {
  	PROC(INDICATE_MECHS, indicate_mechs),
          PROC(GET_CALL_CONTEXT, get_call_context),
          PROC(IMPORT_AND_CANON_NAME, import_and_canon_name),
          PROC(EXPORT_CRED, export_cred),
          PROC(IMPORT_CRED, import_cred),
          PROC(ACQUIRE_CRED, acquire_cred),
          PROC(STORE_CRED, store_cred),
          PROC(INIT_SEC_CONTEXT, init_sec_context),
          PROC(ACCEPT_SEC_CONTEXT, accept_sec_context),
          PROC(RELEASE_HANDLE, release_handle),
          PROC(GET_MIC, get_mic),
          PROC(VERIFY, verify),
          PROC(WRAP, wrap),
          PROC(UNWRAP, unwrap),
          PROC(WRAP_SIZE_LIMIT, wrap_size_limit),
  };
  
  
  
  /*
   * Common transport functions
   */
  
  static const struct rpc_program gssp_program;
  
  static int gssp_rpc_create(struct net *net, struct rpc_clnt **_clnt)
  {
  	static const struct sockaddr_un gssp_localaddr = {
  		.sun_family		= AF_LOCAL,
  		.sun_path		= GSSPROXY_SOCK_PATHNAME,
  	};
  	struct rpc_create_args args = {
  		.net		= net,
  		.protocol	= XPRT_TRANSPORT_LOCAL,
  		.address	= (struct sockaddr *)&gssp_localaddr,
  		.addrsize	= sizeof(gssp_localaddr),
  		.servername	= "localhost",
  		.program	= &gssp_program,
  		.version	= GSSPROXY_VERS_1,
  		.authflavor	= RPC_AUTH_NULL,
  		/*
  		 * Note we want connection to be done in the caller's
  		 * filesystem namespace.  We therefore turn off the idle
  		 * timeout, which would result in reconnections being
  		 * done without the correct namespace:
  		 */
  		.flags		= RPC_CLNT_CREATE_NOPING |
  				  RPC_CLNT_CREATE_NO_IDLE_TIMEOUT
  	};
  	struct rpc_clnt *clnt;
  	int result = 0;
  
  	clnt = rpc_create(&args);
  	if (IS_ERR(clnt)) {
  		dprintk("RPC:       failed to create AF_LOCAL gssproxy "
  				"client (errno %ld).\n", PTR_ERR(clnt));
  		result = PTR_ERR(clnt);
  		*_clnt = NULL;
  		goto out;
  	}
  
  	dprintk("RPC:       created new gssp local client (gssp_local_clnt: "
  			"%p)\n", clnt);
  	*_clnt = clnt;
  
  out:
  	return result;
  }
  
  void init_gssp_clnt(struct sunrpc_net *sn)
  {
  	mutex_init(&sn->gssp_lock);
  	sn->gssp_clnt = NULL;
  }
  
  int set_gssp_clnt(struct net *net)
  {
  	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
  	struct rpc_clnt *clnt;
  	int ret;
  
  	mutex_lock(&sn->gssp_lock);
  	ret = gssp_rpc_create(net, &clnt);
  	if (!ret) {
  		if (sn->gssp_clnt)
  			rpc_shutdown_client(sn->gssp_clnt);
  		sn->gssp_clnt = clnt;
  	}
  	mutex_unlock(&sn->gssp_lock);
  	return ret;
  }
  
  void clear_gssp_clnt(struct sunrpc_net *sn)
  {
  	mutex_lock(&sn->gssp_lock);
  	if (sn->gssp_clnt) {
  		rpc_shutdown_client(sn->gssp_clnt);
  		sn->gssp_clnt = NULL;
  	}
  	mutex_unlock(&sn->gssp_lock);
  }
  
  static struct rpc_clnt *get_gssp_clnt(struct sunrpc_net *sn)
  {
  	struct rpc_clnt *clnt;
  
  	mutex_lock(&sn->gssp_lock);
  	clnt = sn->gssp_clnt;
  	if (clnt)
  		atomic_inc(&clnt->cl_count);
  	mutex_unlock(&sn->gssp_lock);
  	return clnt;
  }
  
  static int gssp_call(struct net *net, struct rpc_message *msg)
  {
  	struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
  	struct rpc_clnt *clnt;
  	int status;
  
  	clnt = get_gssp_clnt(sn);
  	if (!clnt)
  		return -EIO;
  	status = rpc_call_sync(clnt, msg, 0);
  	if (status < 0) {
  		dprintk("gssp: rpc_call returned error %d\n", -status);
  		switch (status) {
  		case -EPROTONOSUPPORT:
  			status = -EINVAL;
  			break;
  		case -ECONNREFUSED:
  		case -ETIMEDOUT:
  		case -ENOTCONN:
  			status = -EAGAIN;
  			break;
  		case -ERESTARTSYS:
  			if (signalled ())
  				status = -EINTR;
  			break;
  		default:
  			break;
  		}
  	}
  	rpc_release_client(clnt);
  	return status;
  }
  
  static void gssp_free_receive_pages(struct gssx_arg_accept_sec_context *arg)
  {
  	unsigned int i;
  
  	for (i = 0; i < arg->npages && arg->pages[i]; i++)
  		__free_page(arg->pages[i]);
  
  	kfree(arg->pages);
  }
  
  static int gssp_alloc_receive_pages(struct gssx_arg_accept_sec_context *arg)
  {
  	unsigned int i;
  
  	arg->npages = DIV_ROUND_UP(NGROUPS_MAX * 4, PAGE_SIZE);
  	arg->pages = kcalloc(arg->npages, sizeof(struct page *), GFP_KERNEL);
  	if (!arg->pages)
  		return -ENOMEM;
  	for (i = 0; i < arg->npages; i++) {
  		arg->pages[i] = alloc_page(GFP_KERNEL);
  		if (!arg->pages[i]) {
  			gssp_free_receive_pages(arg);
  			return -ENOMEM;
  		}
  	}
  	return 0;
  }
  
  static char *gssp_stringify(struct xdr_netobj *netobj)
  {
  	return kmemdup_nul(netobj->data, netobj->len, GFP_KERNEL);
  }
  
  static void gssp_hostbased_service(char **principal)
  {
  	char *c;
  
  	if (!*principal)
  		return;
  
  	/* terminate and remove realm part */
  	c = strchr(*principal, '@');
  	if (c) {
  		*c = '\0';
  
  		/* change service-hostname delimiter */
  		c = strchr(*principal, '/');
  		if (c)
  			*c = '@';
  	}
  	if (!c) {
  		/* not a service principal */
  		kfree(*principal);
  		*principal = NULL;
  	}
  }
  
  /*
   * Public functions
   */
  
  /* numbers somewhat arbitrary but large enough for current needs */
  #define GSSX_MAX_OUT_HANDLE	128
  #define GSSX_MAX_SRC_PRINC	256
  #define GSSX_KMEMBUF (GSSX_max_output_handle_sz + \
  			GSSX_max_oid_sz + \
  			GSSX_max_princ_sz + \
  			sizeof(struct svc_cred))
  
  int gssp_accept_sec_context_upcall(struct net *net,
  				struct gssp_upcall_data *data)
  {
  	struct gssx_ctx ctxh = {
  		.state = data->in_handle
  	};
  	struct gssx_arg_accept_sec_context arg = {
  		.input_token = data->in_token,
  	};
  	struct gssx_ctx rctxh = {
  		/*
  		 * pass in the max length we expect for each of these
  		 * buffers but let the xdr code kmalloc them:
  		 */
  		.exported_context_token.len = GSSX_max_output_handle_sz,
  		.mech.len = GSS_OID_MAX_LEN,
  		.targ_name.display_name.len = GSSX_max_princ_sz,
  		.src_name.display_name.len = GSSX_max_princ_sz
  	};
  	struct gssx_res_accept_sec_context res = {
  		.context_handle = &rctxh,
  		.output_token = &data->out_token
  	};
  	struct rpc_message msg = {
  		.rpc_proc = &gssp_procedures[GSSX_ACCEPT_SEC_CONTEXT],
  		.rpc_argp = &arg,
  		.rpc_resp = &res,
  		.rpc_cred = NULL, /* FIXME ? */
  	};
  	struct xdr_netobj client_name = { 0 , NULL };
  	struct xdr_netobj target_name = { 0, NULL };
  	int ret;
  
  	if (data->in_handle.len != 0)
  		arg.context_handle = &ctxh;
  	res.output_token->len = GSSX_max_output_token_sz;
  
  	ret = gssp_alloc_receive_pages(&arg);
  	if (ret)
  		return ret;
  
  	ret = gssp_call(net, &msg);
  
  	gssp_free_receive_pages(&arg);
  
  	/* we need to fetch all data even in case of error so
  	 * that we can free special strctures is they have been allocated */
  	data->major_status = res.status.major_status;
  	data->minor_status = res.status.minor_status;
  	if (res.context_handle) {
  		data->out_handle = rctxh.exported_context_token;
  		data->mech_oid.len = rctxh.mech.len;
  		if (rctxh.mech.data) {
  			memcpy(data->mech_oid.data, rctxh.mech.data,
  						data->mech_oid.len);
  			kfree(rctxh.mech.data);
  		}
  		client_name = rctxh.src_name.display_name;
  		target_name = rctxh.targ_name.display_name;
  	}
  
  	if (res.options.count == 1) {
  		gssx_buffer *value = &res.options.data[0].value;
  		/* Currently we only decode CREDS_VALUE, if we add
  		 * anything else we'll have to loop and match on the
  		 * option name */
  		if (value->len == 1) {
  			/* steal group info from struct svc_cred */
  			data->creds = *(struct svc_cred *)value->data;
  			data->found_creds = 1;
  		}
  		/* whether we use it or not, free data */
  		kfree(value->data);
  	}
  
  	if (res.options.count != 0) {
  		kfree(res.options.data);
  	}
  
  	/* convert to GSS_NT_HOSTBASED_SERVICE form and set into creds */
  	if (data->found_creds) {
  		if (client_name.data) {
  			data->creds.cr_raw_principal =
  					gssp_stringify(&client_name);
  			data->creds.cr_principal =
  					gssp_stringify(&client_name);
  			gssp_hostbased_service(&data->creds.cr_principal);
  		}
  		if (target_name.data) {
  			data->creds.cr_targ_princ =
  					gssp_stringify(&target_name);
  			gssp_hostbased_service(&data->creds.cr_targ_princ);
  		}
  	}
  	kfree(client_name.data);
  	kfree(target_name.data);
  
  	return ret;
  }
  
  void gssp_free_upcall_data(struct gssp_upcall_data *data)
  {
  	kfree(data->in_handle.data);
  	kfree(data->out_handle.data);
  	kfree(data->out_token.data);
  	free_svc_cred(&data->creds);
  }
  
  /*
   * Initialization stuff
   */
  static unsigned int gssp_version1_counts[ARRAY_SIZE(gssp_procedures)];
  static const struct rpc_version gssp_version1 = {
  	.number		= GSSPROXY_VERS_1,
  	.nrprocs	= ARRAY_SIZE(gssp_procedures),
  	.procs		= gssp_procedures,
  	.counts		= gssp_version1_counts,
  };
  
  static const struct rpc_version *gssp_version[] = {
  	NULL,
  	&gssp_version1,
  };
  
  static struct rpc_stat gssp_stats;
  
  static const struct rpc_program gssp_program = {
  	.name		= "gssproxy",
  	.number		= GSSPROXY_PROGRAM,
  	.nrvers		= ARRAY_SIZE(gssp_version),
  	.version	= gssp_version,
  	.stats		= &gssp_stats,
  };
  