NFSSVC(2) BSD Programmer's Manual NFSSVC(2)NAMEnfssvc - NFS services
SYNOPSIS
#include <unistd.h>
#include <nfs/nfs.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, there is no longer a need to call nfssvc() with the
flags argument set to NFSSVC_BIOD since this functionality has been re-
placed by a nfsiod implementation using kernel threads. See nfsd(8) and
sysctl(8) for further discussion. 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 */
u_int ncd_authlen; /* Length of authenticator string */
u_char *ncd_authstr; /* Authenticator string */
u_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 set to
ENEEDAUTH whenever the client side requires an "rcmd" authentication
ticket for the user. mount_nfs(8) will attempt to get the Kerberos tick-
et, 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 struc-
ture. 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 re-
ceives 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.
RETURN VALUES
Normally nfssvc does not return unless the server is terminated by a sig-
nal when a value of 0 is returned. Otherwise, -1 is returned and the glo-
bal 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 superuser.
SEE ALSOmount_nfs(8), nfsd(8), sysctl(8)HISTORY
The nfssvc function first appeared in 4.4BSD.
BUGS
The nfssvc system call is designed specifically for the NFS support dae-
mons and as such is specific to their requirements. It should really re-
turn 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.
MirOS BSD #10-current June 9, 1993 1
