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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
     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.

     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
     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) 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
                        authentication 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
     structures are assumed to be valid and sometimes to be unchanged from a
     previous call, such that nfssvc() must be used with extreme care.