AUTH(2) AUTH(2)
NAME
amount, newns, addns, login, noworld, procsetuser,
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_respondAI, auth_userpasswd,
auth_getuserpasswd, auth_getinfo - routines for
authenticating users
SYNOPSIS
#include <u.h>
#include <libc.h>
#include <auth.h>
int newns(char *user, char *nsfile);
int addns(char *user, char *nsfile);
int amount(int fd, char *old, int flag, char
*aname);
int login(char *user, char *password, char
*namespace);
int noworld(char *user);
int procsetuser(char *user);
AuthInfo* auth_proxy(int fd, AuthGetkey *getkey, char *fmt,
...);
AuthInfo* fauth_proxy(int fd, AuthRpc *rpc, AuthGetkey
*getkey,
char *params);
AuthRpc* auth_allocrpc(int afd);
void auth_freerpc(AuthRpc *rpc);
uint auth_rpc(AuthRpc *rpc, char *verb, void *a,
int n);
int auth_getkey(char *params);
int (*amount_getkey)(char*);
void auth_freeAI(AuthInfo *ai);
int auth_chuid(AuthInfo *ai, char *ns);
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AUTH(2) AUTH(2)
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 *get-
key, char *fmt, ...);
int auth_respondAI(void *chal, uint nchal,
char *user, uint nuser, void *resp, uint nresp, AuthInfo
**ai, AuthGetkey *getkey, char *fmt, ...);
AuthInfo* auth_userpasswd(char*user, char*password);
UserPasswd* auth_getuserpasswd(AuthGetkey *getkey,
char*fmt, ...);
AuthInfo* auth_getinfo(AuthRpc*);
DESCRIPTION
This library, in concert with factotum(4), is used to
authenticate users. It provides the primary interface to
factotum.
Newns builds a name space for user. It opens the file nsfile
(/lib/namespace is used if nsfile is null), copies the old
environment, erases the current name space, sets the envi-
ronment variables user and home, and interprets the commands
in nsfile. The format of nsfile is described in
namespace(6).
Addns also interprets and executes the commands in nsfile.
Unlike newns it applies the command to the current name
space rather than starting from scratch.
Amount is like mount but performs any authentication
required. It should be used instead of mount whenever the
file server being mounted requires authentication. See
bind(2) for a definition of the arguments to mount and
amount.
Login changes the user id of the process to user and recre-
ates the namespace using the file namespace (default
/lib/namespace). It uses auth_userpasswd and auth_chuid.
Noworld returns 1 if the user is in the group noworld in
/adm/users. Otherwise, it returns 0. Noworld is used by
telnetd and ftpd to provide sandboxed access for some users.
Procsetuser changes the user id of the process to user but
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AUTH(2) AUTH(2)
keeps the namespace unchanged. Only hostowner can change
the user to anything other than the none user.
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 can be passed to the cap(3) device to change
the user id of the process. 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 con-
versation.
Auth_proxy proxies an authentication conversation between a
remote server reading and writing fd and a factotum file.
The factotum file used is /mnt/factotum/rpc. An sprint (see
print(2)) of fmt and the variable arg list yields a key tem-
plate (see factotum(4)) specifying the key to use. The tem-
plate 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 authentica-
tions. 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 with the fd of an open factotum connection.
It 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 possess 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,
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AUTH(2) AUTH(2)
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 speci-
fied 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_respondAI is like auth_respond but has an additional ai
output parameter to return an AuthInfo structure on success
that holds protocol specific secret keys derived from the
exchange. The returned AuthInfo structure should be freed
with auth_freeAI by the caller.
Auth_userpasswd verifies a simple user/password pair.
Auth_getuserpasswd retrieves a user/password pair from
factotum if permitted:
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AUTH(2) AUTH(2)
typedef struct UserPasswd {
char *user;
char *passwd;
} UserPasswd;
Auth_getinfo reads an AuthInfo message from rpc and converts
it into a structure. It is only used by the other routines
in this library when communicating with factotum.
Auth_freeAI is used to free an AuthInfo structure returned
by one of these routines. Similary auth_freechal frees a
challenge/response state.
SOURCE
/sys/src/libauth
SEE ALSO
factotum(4), authsrv(2), bind(2)
DIAGNOSTICS
These routines set errstr.
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