plan9fox/sys/man/2/authsrv

.TH AUTHSRV 2
.SH NAME
authdial, passtokey, nvcsum, readnvram, convT2M, convM2T, convTR2M, convM2TR, convA2M, convM2A, convPR2M, convM2PR, _asgetticket, _asrequest, _asgetresp, _asrdresp, _asgetpakkey, authpak_hash, authpak_new, authpak_finish \- routines for communicating with authentication servers
.SH SYNOPSIS
.nf
.PP
.ft L
#include <u.h>
#include <libc.h>
#include <authsrv.h>
.fi
.ta 8n +4n +4n +4n +4n +4n +4n
.PP
.B
int	authdial(char *netroot, char *ad);
.PP
.B
void	passtokey(Authkey *key, char *password)
.PP
.B
uchar	nvcsum(void *mem, int len)
.PP
.B
int	readnvram(Nvrsafe *nv, int flag);
.PPP
.B
int	convT2M(Ticket *t, char *msg, int len, Authkey *key)
.PP
.B
int	convM2T(char *msg, int len, Ticket *t, Authkey *key)
.PP
.B
int	convA2M(Authenticator *a, char *msg, int len, Ticket *t)
.PP
.B
int	convM2A(char *msg, int len, Authenticator *a, Ticket *t)
.PP
.B
int	convTR2M(Ticketreq *tr, char *msg, int len)
.PP
.B
int	convM2TR(char *msg, int len, Ticketreq *tr)
.PP
.B
int	convPR2M(Passwordreq *pr, char *msg, int len, Ticket *t)
.PP
.B
int	convM2PR(char *msg, int len, Passwordreq *pr, Ticket *t)
.PP
.B
int	_asgetticket(int fd, Ticketreq *tr, char *buf, int len)
.PP
.B
int	_asrequest(int fd, Ticketreq *tr)
.PP
.B
int	_asgetresp(int fd, Ticket *t, Authenticator *a, Authkey *key)
.PP
.B
int	_asrdresp(int fd, char *buf, int len)
.PP
.B
int	_asgetpakkey(int fd, Ticketreq *tr, Authkey *a)
.PP
.B
void	authpak_hash(Authkey *k, char *u)
.PP
.B
void	authpak_new(PAKpriv *p, Authkey *k, uchar y[PAKYLEN], int isclient)
.PP
.B
int	authpak_finish(PAKpriv *p, Authkey *k, uchar y[PAKYLEN])
.SH DESCRIPTION
.I Authdial
dials an authentication server over the
network rooted at
.IR net ,
default
.BR /net  .
The authentication domain,
.IR ad ,
specifies which server to call.
If
.I ad
is non-nil,
the connection server
.B cs
(see
.IR ndb (8))
is queried for an entry which contains
.B authdom=\fIad\fP
or
.BR dom=\fIad\fP ,
the former having precedence,
and which also contains an
.B auth
attribute.
If it finds neither, it tries
.BI p9auth. ad
in DNS as the authentication server.
The string dialed is then
.I netroot\fP!\fIserver\fP!ticket
where
.I server
is the value of the
.B auth
attribute.
If no entry is found, the error string is
set to ``no authentication server found''
and -1 is returned.
If
.I authdom
is nil, the string
.IB netroot !$auth! ticket
is used to make the call.
.PP
.I Passtokey
converts
.I password
into a set of cryptographic keys and stores them in the
.I Authkey
structure
.IR key .
.PP
.I Readnvram
reads authentication information into the structure:
.PP
.EX
.ta 4n +4n +8n +4n +4n +4n +4n
struct Nvrsafe
{
	char	machkey[DESKEYLEN];	/* was file server's authid's des key */
	uchar	machsum;
	char	authkey[DESKEYLEN];	/* authid's des key from password */
	uchar	authsum;
	/*
	 * file server config string of device holding full configuration;
	 * secstore key on non-file-servers.
	 */
	char	config[CONFIGLEN];
	uchar	configsum;
	char	authid[ANAMELEN];	/* auth userid, e.g., bootes */
	uchar	authidsum;
	char	authdom[DOMLEN]; /* auth domain, e.g., cs.bell-labs.com */
	uchar	authdomsum;

	uchar	aesmachkey[AESKEYLEN];
	uchar	aesmachsum;
};
.EE
.PP
On Sparc, MIPS, and SGI machines this information is
in non-volatile ram, accessible in the file
.BR #r/nvram .
On x86s and Alphas
.I readnvram
successively opens the following areas stopping with the
first to succeed:
.PP
\- the partition named by the
.B $nvram
environment variable
(commonly set via
.IR plan9.ini (8))
.br
\- the partition
.B #S/sdC0/nvram
.br
\- a file called
.B plan9.nvr
in the partition
.B #S/sdC0/9fat
.br
\- the partition
.B #S/sd00/nvram
.br
\- a file called
.B plan9.nvr
in the partition
.B #S/sd00/9fat
.br
\- a file called
.B plan9.nvr
on a DOS floppy in drive 0
.br
\- a file called
.B plan9.nvr
on a DOS floppy in drive 1
.PP
The
.IR nvcsum s
of the fields
.BR machkey ,
.BR authid ,
and
.B authdom
must match their respective checksum or that field is zeroed.
If
.I flag
is
.B NVwrite
or at least one checksum fails and
.I flag
is
.BR NVwriteonerr ,
.I readnvram
will prompt for new values on
.B #c/cons
and then write them back to the storage area.
If
.I flag
is
.BR NVwritemem ,
.I readnvram
will write the values in
.I *nv
back to the storage area.
.PP
.IR ConvT2M ,
.IR convA2M ,
.IR convTR2M ,
and
.I convPR2M
convert tickets, authenticators, ticket requests, and password change request
structures into transmittable messages.
.IR ConvM2T ,
.IR convM2A ,
.IR convM2TR ,
and
.I convM2PR
are used to convert them back.
.I Key
is used for encrypting the message before transmission and decrypting
after reception.
.IR ConvA2M ,
.IR convM2A ,
.I convPR2M
and
.I convM2PR
encrypt/decrypt the message with the random ticket key.
.PP
The routine
.I _asgetticket
sends a ticket request
.I tr
returning the two encrypted tickets in
.IR buf .
The routine
.I _asrequest
encodes the ticket request
.I tr
and sends it not waiting for a response.
After sending a request,
.I _asgetresp
can be used to receive the response containing a ticket and an optional
authenticator and decrypts the ticket and authenticator using
.IR key .
The routine
.I _asrdresp
receives either a character array or an error string.
On error, it sets errstr and returns -1.  If successful,
it returns the number of bytes received.
.PP
.I Authpak_hash
prepares a
.I Authkey
structure for a password authenticated key exchange (see
.IR authsrv (6))
by calculating the pakhash from a user's aeskey and id
.IR u .
The fuction hashes the password derived aeskey and user id together
using hmac_sha256 and maps the result into two elliptic curve points
PN/PM on the Ed448-goldielocks curve using elligator2.
.PP
.I Authpak_new
generates a new elliptic curve diffie-hellman key pair for a password
authenticated key exchange from a previously hashed
.I Authkey
structure
.IR k .
The randomly generated private key is returned in the
.I PAKpriv
structure passed in
.IR p ,
while the pakhash encrytped public key is returned in
.IR y .
.PP
.I Authpak_finish
completes a password authenticated key exchange, taking the other
sides pakhash encrypted public key
.I y
and our private key
.I p
returning the shared secret pakkey in the
.I Authkey
structure
.IR k .
The function returns zero on success or non-zero on failure (malformed
public key).
.PP
The function
.I _asgetpakkey
establishes a new shared pakkey between the us and the authentication server
for ticket encryption; using the functions above; taking a previously hashed
.I Authkey
.I a
and
.I Ticketreq
.I tr
and returns the shared pakkey in the
.I Authkey
structure. It is usually called before
.I _asrequest
right after
.IR authdial
to negotiate bruteforce resistant ticket encryption for the
ticket request that follows (see
.IR authsrv (6)).
Returns zero on success, or non-zero on error (authenticatoin
server does not support the AuthPAK request or when we got a malformed public key).
.SH SOURCE
.B /sys/src/libauthsrv
.SH SEE ALSO
.IR passwd (1),
.IR cons (3),
.IR dial (2),
.IR authsrv (6),
.SH DIAGNOSTICS
These routines set
.IR errstr .
Integer-valued functions return -1 on error.