DragonFly On-Line Manual Pages

NFSSVC(2)                DragonFly 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 <vfs/nfs/rpcv2.h>
     #include <vfs/nfs/nfs.h>
     #include <unistd.h>

     int
     nfssvc(int flags, void *argstructp);

DESCRIPTION
     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 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) daemon will return from nfssvc() with errno == ENEEDAUTH
     whenever the client side requires an ``rcmd'' authentication 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 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) 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.

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() function 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.

DragonFly 5.7-DEVELOPMENT      February 21, 2020     DragonFly 5.7-DEVELOPMENT