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

NAME
     nfssvc — NFS services

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <sys/param.h>
     #include <sys/mount.h>
     #include <sys/time.h>
     #include <nfs/rpcv2.h>
     #include <nfsserver/nfs.h>
     #include <unistd.h>

     int
     nfssvc(int flags, void *argstructp);

DESCRIPTION
     The nfssvc() system call is used by the NFS daemons to pass information
     into and out of the kernel and also to enter the kernel as a server dae‐
     mon.  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.

     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 */
	     u_char	     *ncd_authstr;   /* Authenticator string */
	     int	     ncd_verflen;    /* and the verifier */
	     u_char	     *ncd_verfstr;
	     NFSKERBKEY_T    ncd_key;	     /* Session key */
     };

     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) utility will return from nfssvc() with errno ==
     ENEEDAUTH whenever the client side requires an ``rcmd'' authentication
     ticket for the user.  The mount_nfs(8) utility 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 authentication 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_int32_t	     nsd_haddr;	     /* Ip address of client */
	     struct ucred    nsd_cr;	     /* Cred. uid maps to */
	     int	     nsd_authlen;    /* Length of auth string (ret) */
	     u_char	     *nsd_authstr;   /* Auth string (ret) */
	     int	     nsd_verflen;    /* and the verifier */
	     u_char	     *nsd_verfstr;
	     struct timeval  nsd_timestamp;  /* timestamp from verifier */
	     u_int32_t	     nsd_ttl;	     /* credential ttl (sec) */
	     NFSKERBKEY_T    nsd_key;	     /* Session key */
     };

     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) utility will attempt to authenti‐
     cate 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 princi‐
     pal to a local name and getting a set of credentials for that user via
     getpwnam(3) and getgrouplist(3).  If successful, the nfsd(8) utility 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.

RETURN VALUES
     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.

ERRORS
     [ENEEDAUTH]	This special error value is really used for authenti‐
			cation support, particularly Kerberos, as explained
			above.

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

SEE ALSO
     mount_nfs(8), nfsd(8), nfsiod(8)

HISTORY
     The nfssvc() system call first appeared in 4.4BSD.

BUGS
     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 argument struc‐
     tures are assumed to be valid and sometimes to be unchanged from a previ‐
     ous call, such that nfssvc() must be used with extreme care.

BSD				 June 9, 1993				   BSD
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