| NFSSVC(2) | System Calls Manual | NFSSVC(2) | 
nfssvc —
#include <unistd.h>
#include <nfs/nfs.h>
int
  
  nfssvc(int
    flags, void
    *argstructp);
nfssvc() function is used by the NFS daemons to pass
  information into and out of the kernel and also to enter the kernel as a
  server daemon. The flags argument consists of several
  bits that show what action is to be taken once in the kernel and the
  argstructp points to one of three structures depending
  on which bits are set in flags.
nfssvc() is called with the flag
  NFSSVC_NFSD and a pointer to a
struct nfsd_srvargs {
	struct nfsd	*nsd_nfsd;	/* Pointer to in kernel nfsd struct */
	uid_t		nsd_uid;	/* Effective uid mapped to cred */
	u_long		nsd_haddr;	/* Ip address of client */
	struct ucred	nsd_cr;		/* Cred. uid maps to */
	int		nsd_authlen;	/* Length of auth string (ret) */
	char		*nsd_authstr;	/* Auth string (ret) */
};
to enter the kernel as an
    nfsd(8) daemon. Whenever an
    nfsd(8) daemon receives a
    Kerberos authentication ticket, it will return from
    nfssvc() with errno set to
    ENEEDAUTH. The
    nfsd(8) will attempt to
    authenticate the ticket and generate a set of credentials on the server for
    the “user id” specified in the field nsd_uid. This is done by
    first authenticating the Kerberos ticket and then mapping the Kerberos
    principal to a local name and getting a set of credentials for that user via
    getpwnam(3) and
    getgrouplist(3). If
    successful, the nfsd(8) will
    call nfssvc() with the
    NFSSVC_NFSD and
    NFSSVC_AUTHIN flags set to pass the credential
    mapping in nsd_cr into the kernel to be cached on the server socket for that
    client. If the authentication failed,
    nfsd(8) calls
    nfssvc() with the flags
    NFSSVC_NFSD and
    NFSSVC_AUTHINFAIL to denote an authentication
    failure.
The master nfsd(8)
    server daemon calls nfssvc() with the flag
    NFSSVC_ADDSOCK and a pointer to a
struct nfsd_args {
	int	sock;		/* Socket to serve */
	caddr_t	name;		/* Client address for connection based sockets */
	int	namelen;	/* Length of name */
};
to pass a server side NFS socket into the kernel for servicing by the nfsd(8) daemons.
nfssvc() with the flag
  NFSSVC_SETEXPORTSLIST and a pointer to a
  struct mountd_exports_list object to atomically change
  the exports lists of a specific file system. This structure has the following
  fields:
nfssvc does not return unless the server is
  terminated by a signal when a value of 0 is returned. Otherwise, -1 is
  returned and the global variable errno is set to specify
  the error.
nfssvc function first appeared in
  4.4BSD.
nfssvc system call is designed specifically for the
  NFS support daemons and as such is specific to their requirements. It should
  really return values to indicate the need for authentication support, since
  ENEEDAUTH is not really an error. Several fields of
  the argument structures are assumed to be valid and sometimes to be unchanged
  from a previous call, such that nfssvc must be used
  with extreme care.
| December 30, 2006 | NetBSD 9.3 |