plucky (2) nfssvc.2freebsd.gz

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 */
             uint32_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 */
             uint32_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.