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NFSSVC(2)			     BSD System Calls Manual				NFSSVC(2)

     nfssvc -- NFS services

     #include <unistd.h>
     #include <nfs/nfs.h>

     nfssvc(int flags, void *argstructp);

     The 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 sev-
     eral 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.

     On the client side, nfsiod(8) calls nfssvc() with the flags argument set to NFSSVC_BIOD and
     argstructp set to NULL to enter the kernel as a block I/O server daemon.  For NQNFS,
     mount_nfs(8) calls nfssvc() with the NFSSVC_MNTD flag, optionally or'd with the flags
     NFSSVC_GOTAUTH and NFSSVC_AUTHINFAIL along with a pointer to a

     struct nfsd_cargs {
	     char	     *ncd_dirp;      /* Mount dir path */
	     uid_t	     ncd_authuid;    /* Effective uid */
	     int	     ncd_authtype;   /* Type of authenticator */
	     int	     ncd_authlen;    /* Length of authenticator string */
	     char	     *ncd_authstr;   /* Authenticator string */

     structure.  The initial call has only the NFSSVC_MNTD flag set to specify service for the
     mount point.  If the mount point is using Kerberos, then the mount_nfs(8) daemon will return
     from nfssvc() with errno == ENEEDAUTH whenever the client side requires an ``rcmd'' authen-
     tication ticket for the user.  Mount_nfs(8) will attempt to get the Kerberos ticket, and if
     successful will call nfssvc() with the flags NFSSVC_MNTD and NFSSVC_GOTAUTH after filling
     the ticket into the ncd_authstr field and setting the ncd_authlen and ncd_authtype fields of
     the nfsd_cargs structure.	If mount_nfs(8) failed to get the ticket, nfssvc() will be called
     with the flags NFSSVC_MNTD, NFSSVC_GOTAUTH and NFSSVC_AUTHINFAIL to denote a failed authen-
     tication attempt.

     On the server side, 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 == 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.

     Normally 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.

     [ENEEDAUTH]	This special error value is really used for authentication support, par-
			ticularly Kerberos, as explained above.

     [EPERM]		The caller is not the super-user.

     nfsd(8), mount_nfs(8), nfsiod(8)

     The nfssvc function first appeared in 4.4BSD.

     The 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 argu-
     ment structures are assumed to be valid and sometimes to be unchanged from a previous call,
     such that nfssvc must be used with extreme care.

BSD					   June 9, 1993 				      BSD
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