nfssvc -- NFS services
Standard C Library (libc, -lc)
#include <sys/param.h>
#include <sys/mount.h>
#include <sys/time.h>
#include <nfs/rpcv2.h>
#include <nfs/nfs.h>
#include <unistd.h>
int
nfssvc(int flags, void *argstructp);
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.
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.
[ENEEDAUTH] This special error value is really used for authentication
support, particularly Kerberos, as explained
above.
[EPERM] The caller is not the super-user.
mount_nfs(8), nfsd(8), nfsiod(8)
The nfssvc() system call first appeared in 4.4BSD.
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.
FreeBSD 5.2.1 June 9, 1993 FreeBSD 5.2.1 [ Back ] | 