NFSSVC(2) | System Calls Manual | NFSSVC(2) |
nfssvc
—
#include <unistd.h>
#include <nfs/nfs.h>
int
nfssvc
(int
flags, void
*argstructp);
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.
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 set to
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.
nfssvc
() with the flag
NFSSVC_SETEXPORTSLIST
and a pointer to a
struct mountd_exports_list object to atomically change
the exports lists of a specific file system. This structure has the following
fields:
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.
nfssvc
function first appeared in
4.4BSD.
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.
December 30, 2006 | NetBSD 9.0 |