/*
   * linux/net/sunrpc/auth_unix.c
   *
   * UNIX-style authentication; no AUTH_SHORT support
   *
   * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
   */
  
  #include <linux/slab.h>
  #include <linux/types.h>
  #include <linux/sched.h>
  #include <linux/module.h>
  #include <linux/sunrpc/clnt.h>
  #include <linux/sunrpc/auth.h>
  #include <linux/user_namespace.h>
  
  #define NFS_NGROUPS	16
  
  struct unx_cred {
  	struct rpc_cred		uc_base;
  	kgid_t			uc_gid;
  	kgid_t			uc_gids[NFS_NGROUPS];
  };
  #define uc_uid			uc_base.cr_uid
  
  #define UNX_WRITESLACK		(21 + XDR_QUADLEN(UNX_MAXNODENAME))
  
  #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
  # define RPCDBG_FACILITY	RPCDBG_AUTH
  #endif
  
  static struct rpc_auth		unix_auth;
  static const struct rpc_credops	unix_credops;
  
  static struct rpc_auth *
  unx_create(struct rpc_auth_create_args *args, struct rpc_clnt *clnt)
  {
  	dprintk("RPC:       creating UNIX authenticator for client %p
  ",
  			clnt);
  	atomic_inc(&unix_auth.au_count);
  	return &unix_auth;
  }
  
  static void
  unx_destroy(struct rpc_auth *auth)
  {
  	dprintk("RPC:       destroying UNIX authenticator %p
  ", auth);
  	rpcauth_clear_credcache(auth->au_credcache);
  }
  
  /*
   * Lookup AUTH_UNIX creds for current process
   */
  static struct rpc_cred *
  unx_lookup_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags)
  {
  	return rpcauth_lookup_credcache(auth, acred, flags);
  }
  
  static struct rpc_cred *
  unx_create_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags)
  {
  	struct unx_cred	*cred;
  	unsigned int groups = 0;
  	unsigned int i;
  
  	dprintk("RPC:       allocating UNIX cred for uid %d gid %d
  ",
  			from_kuid(&init_user_ns, acred->uid),
  			from_kgid(&init_user_ns, acred->gid));
  
  	if (!(cred = kmalloc(sizeof(*cred), GFP_NOFS)))
  		return ERR_PTR(-ENOMEM);
  
  	rpcauth_init_cred(&cred->uc_base, acred, auth, &unix_credops);
  	cred->uc_base.cr_flags = 1UL << RPCAUTH_CRED_UPTODATE;
  
  	if (acred->group_info != NULL)
  		groups = acred->group_info->ngroups;
  	if (groups > NFS_NGROUPS)
  		groups = NFS_NGROUPS;
  
  	cred->uc_gid = acred->gid;
  	for (i = 0; i < groups; i++)
  		cred->uc_gids[i] = GROUP_AT(acred->group_info, i);
  	if (i < NFS_NGROUPS)
  		cred->uc_gids[i] = INVALID_GID;
  
  	return &cred->uc_base;
  }
  
  static void
  unx_free_cred(struct unx_cred *unx_cred)
  {
  	dprintk("RPC:       unx_free_cred %p
  ", unx_cred);
  	kfree(unx_cred);
  }
  
  static void
  unx_free_cred_callback(struct rcu_head *head)
  {
  	struct unx_cred *unx_cred = container_of(head, struct unx_cred, uc_base.cr_rcu);
  	unx_free_cred(unx_cred);
  }
  
  static void
  unx_destroy_cred(struct rpc_cred *cred)
  {
  	call_rcu(&cred->cr_rcu, unx_free_cred_callback);
  }
  
  /*
   * Match credentials against current process creds.
   * The root_override argument takes care of cases where the caller may
   * request root creds (e.g. for NFS swapping).
   */
  static int
  unx_match(struct auth_cred *acred, struct rpc_cred *rcred, int flags)
  {
  	struct unx_cred	*cred = container_of(rcred, struct unx_cred, uc_base);
  	unsigned int groups = 0;
  	unsigned int i;
  
  
  	if (!uid_eq(cred->uc_uid, acred->uid) || !gid_eq(cred->uc_gid, acred->gid))
  		return 0;
  
  	if (acred->group_info != NULL)
  		groups = acred->group_info->ngroups;
  	if (groups > NFS_NGROUPS)
  		groups = NFS_NGROUPS;
  	for (i = 0; i < groups ; i++)
  		if (!gid_eq(cred->uc_gids[i], GROUP_AT(acred->group_info, i)))
  			return 0;
  	if (groups < NFS_NGROUPS && gid_valid(cred->uc_gids[groups]))
  		return 0;
  	return 1;
  }
  
  /*
   * Marshal credentials.
   * Maybe we should keep a cached credential for performance reasons.
   */
  static __be32 *
  unx_marshal(struct rpc_task *task, __be32 *p)
  {
  	struct rpc_clnt	*clnt = task->tk_client;
  	struct unx_cred	*cred = container_of(task->tk_rqstp->rq_cred, struct unx_cred, uc_base);
  	__be32		*base, *hold;
  	int		i;
  
  	*p++ = htonl(RPC_AUTH_UNIX);
  	base = p++;
  	*p++ = htonl(jiffies/HZ);
  
  	/*
  	 * Copy the UTS nodename captured when the client was created.
  	 */
  	p = xdr_encode_array(p, clnt->cl_nodename, clnt->cl_nodelen);
  
  	*p++ = htonl((u32) from_kuid(&init_user_ns, cred->uc_uid));
  	*p++ = htonl((u32) from_kgid(&init_user_ns, cred->uc_gid));
  	hold = p++;
  	for (i = 0; i < 16 && gid_valid(cred->uc_gids[i]); i++)
  		*p++ = htonl((u32) from_kgid(&init_user_ns, cred->uc_gids[i]));
  	*hold = htonl(p - hold - 1);		/* gid array length */
  	*base = htonl((p - base - 1) << 2);	/* cred length */
  
  	*p++ = htonl(RPC_AUTH_NULL);
  	*p++ = htonl(0);
  
  	return p;
  }
  
  /*
   * Refresh credentials. This is a no-op for AUTH_UNIX
   */
  static int
  unx_refresh(struct rpc_task *task)
  {
  	set_bit(RPCAUTH_CRED_UPTODATE, &task->tk_rqstp->rq_cred->cr_flags);
  	return 0;
  }
  
  static __be32 *
  unx_validate(struct rpc_task *task, __be32 *p)
  {
  	rpc_authflavor_t	flavor;
  	u32			size;
  
  	flavor = ntohl(*p++);
  	if (flavor != RPC_AUTH_NULL &&
  	    flavor != RPC_AUTH_UNIX &&
  	    flavor != RPC_AUTH_SHORT) {
  		printk("RPC: bad verf flavor: %u
  ", flavor);
  		return ERR_PTR(-EIO);
  	}
  
  	size = ntohl(*p++);
  	if (size > RPC_MAX_AUTH_SIZE) {
  		printk("RPC: giant verf size: %u
  ", size);
  		return ERR_PTR(-EIO);
  	}
  	task->tk_rqstp->rq_cred->cr_auth->au_rslack = (size >> 2) + 2;
  	p += (size >> 2);
  
  	return p;
  }
  
  int __init rpc_init_authunix(void)
  {
  	return rpcauth_init_credcache(&unix_auth);
  }
  
  void rpc_destroy_authunix(void)
  {
  	rpcauth_destroy_credcache(&unix_auth);
  }
  
  const struct rpc_authops authunix_ops = {
  	.owner		= THIS_MODULE,
  	.au_flavor	= RPC_AUTH_UNIX,
  	.au_name	= "UNIX",
  	.create		= unx_create,
  	.destroy	= unx_destroy,
  	.lookup_cred	= unx_lookup_cred,
  	.crcreate	= unx_create_cred,
  };
  
  static
  struct rpc_auth		unix_auth = {
  	.au_cslack	= UNX_WRITESLACK,
  	.au_rslack	= 2,			/* assume AUTH_NULL verf */
  	.au_ops		= &authunix_ops,
  	.au_flavor	= RPC_AUTH_UNIX,
  	.au_count	= ATOMIC_INIT(0),
  };
  
  static
  const struct rpc_credops unix_credops = {
  	.cr_name	= "AUTH_UNIX",
  	.crdestroy	= unx_destroy_cred,
  	.crbind		= rpcauth_generic_bind_cred,
  	.crmatch	= unx_match,
  	.crmarshal	= unx_marshal,
  	.crrefresh	= unx_refresh,
  	.crvalidate	= unx_validate,
  };