AUTH(3)

NAME
auth_proxy, fauth_proxy, auth_allocrpc, auth_freerpc, auth_rpc, auth_getkey, amount_getkey, auth_freeAI, auth_chuid, auth_challenge, auth_response, auth_freechal, auth_respond, auth_userpasswd, auth_getuserpasswd, auth_getinfo, fsauth_proxy, fsfauth_proxy, fsamount, nsamount- routines for authenticating users

SYNOPSIS

#include <u.h>
#include <libc.h>
#include <auth.h>

AuthInfo*    auth_proxy(int fd, AuthGetkey *getkey, char *fmt, ...);

AuthInfo*    fauth_proxy(int fd, AuthRpc *rpc, AuthGetkey *getkey,
char *params);

AuthRpc*    auth_allocrpc(void);

void    auth_freerpc(AuthRpc *rpc);

uint    auth_rpc(AuthRpc *rpc, char *verb, void *a, int n);

int    auth_getkey(char *proto, char *dom);

int    (*amount_getkey)(char*, char*);

void    auth_freeAI(AuthInfo *ai);

int    auth_chuid(AuthInfo *ai, char *ns);

Chalstate*    auth_challenge(char *fmt, ...);

AuthInfo*    auth_response(Chalstate*);

void    auth_freechal(Chalstate*);

int    auth_respond(void *chal, uint nchal, char *user, uint nuser, void *resp, uint nresp, AuthGetkey *getkey, char *fmt, ...);

AuthInfo*    auth_userpasswd(char*user, char*password);

UserPasswd*    auth_getuserpasswd(AuthGetkey *getkey, char*fmt, ...);

AuthInfo*    auth_getinfo(AuthRpc *rpc);

#include <9pclient.h>

AuthInfo*    fsauth_proxy(CFid *fid, AuthGetkey *getkey, char *fmt, ...);

AuthInfo*    fsfauth_proxy(CFid *fid, AuthRpc *rpc, AuthGetkey *getkey,
char *params);

CFsys*    fsamount(int fd, char *aname);

CFsys*    nsamount(char *name, char *aname);

DESCRIPTION

This library, in concert with factotum(4), is used to authenticate users. It provides the primary interface to factotum.

The following routines use the AuthInfo structure returned after a successful authentication by factotum(4).

    typedef struct
    {
    	char	*cuid;		/* caller id */
    	char	*suid;		/* server id */
    	char	*cap;			/* capability */
    	int	nsecret;		/* length of secret */
    	uchar	*secret;		/* secret */
    } AuthInfo;

The fields cuid and suid point to the authenticated ids of the client and server. Cap is a capability returned only to the server. It is meaningful only on Plan 9. Secret is an nsecret-byte shared secret that can be used by the client and server to create encryption and hashing keys for the rest of the conversation.

Auth_proxy proxies an authentication conversation between a remote server reading and writing fd and a factotum file, as opened by auth_allocrpc. An sprint (see print(3)) of fmt and the variable arg list yields a key template (see factotum(4)) specifying the key to use. The template must specify at least the protocol ( proto=xxx) and the role (either role=client or role=server). Auth_proxy either returns an allocated AuthInfo structure, or sets the error string and returns nil.

Fauth_proxy can be used instead of auth_proxy if a single connection to factotum will be used for multiple authentications. This is necessary, for example, for newns which must open the factotum file before wiping out the namespace. Fauth_proxy takes as an argument a pointer to an AuthRpc structure which contains an fd for an open connection to factotum in addition to storage and state information for the protocol. An AuthRpc structure is obtained by calling auth_allocrpc. Auth_allocrpc arranges a connection to factotum, either by opening /mnt/factotum/rpc or by using 9pclient(3) to connect to a factotum service posted in the current name space. The returned connection is freed using auth_freerpc. Individual commands can be sent to factotum(4) by invoking auth_rpc.

Both auth_proxy and fauth_proxy take a pointer to a routine, getkey, to invoke should factotum not posess a key for the authentication. If getkey is nil, the authentication fails. Getkey is called with a key template for the desired key. We have provided a generic routine, auth_getkey, which queries the user for the key information and passes it to factotum. This is the default for the global variable, amount_getkey, which holds a pointer to the key prompting routine used by amount.

Auth_chuid uses the cuid and cap fields of an AuthInfo structure to change the user id of the current process and uses ns, default /lib/namespace, to build it a new name space.

Auth_challenge and auth_response perform challenge/response protocols with factotum. State between the challenge and response phase are kept in the Chalstate structure:

    struct Chalstate
    {
    	char	*user;
    	char	chal[MAXCHLEN];
    	int	nchal;
    	void	*resp;
    	int	nresp;
    /* for implementation only */
    	int	afd;
    	AuthRpc	*rpc;
    	char	userbuf[MAXNAMELEN];
    	int	userinchal;
    };

Auth_challenge requires a key template generated by an sprint of fmt and the variable arguments. It must contain the protocol (proto=xxx) and depending on the protocol, the user name ( user=xxx). P9cr and vnc expect the user specified as an attribute in the key template and apop, cram, and chap expect it in the user field of the arg to auth_response. For all protocols, the response is returned to auth_response in the resp field of the Chalstate. Chalstate.nresp must be the length of the response.

Supply to auth_respond a challenge string and the fmt and args specifying a key, and it will use factotum to return the proper user and response.

Auth_userpasswd verifies a simple user/password pair. Auth_getuserpasswd retrieves a user/password pair from factotum if permitted.

Auth_getinfo reads an AuthInfo message from factotum and converts it into a structure. It is only used by the other routines in this library when communicating with factotum.

    typedef struct UserPasswd {
    	char	*user;
    	char	*passwd;
    } UserPasswd;

Auth_freeAI is used to free an AuthInfo structure returned by one of these routines. Similary auth_freechal frees a challenge/response state.

Fsauth_proxy and fsfauth_proxy are like auth_proxy and fauth_proxy but execute the protocol on a CFid* (see 9pclient(3)) instead of a file descriptor.

Fsamount and nsamount are like fsmount and nsmount (see 9pclient(3)) but use factotum to authenticate to the file servers.

SOURCE
/usr/local/plan9/src/libauth

SEE ALSO
factotum(4), authsrv(3)

DIAGNOSTICS
These routines set errstr.