1993/0330/port/auth.c (diff list | history)

port/auth.c on 1993/0330
1993/0330		#include "u.h" #include "../port/lib.h" #include "mem.h" #include "dat.h" #include "fns.h" #include "io.h" #include "../port/error.h" typedef struct Crypt Crypt; struct Crypt { Crypt *next; Ticket t; Authenticator a; char tbuf[TICKETLEN]; /* remote ticket */ }; typedef struct Session Session; struct Session { Lock; Crypt *cache; /* cache of tickets */ char cchal[CHALLEN]; /* client challenge */ char schal[CHALLEN]; /* server challenge */ char authid[NAMELEN]; /* server encryption uid */ char authdom[DOMLEN]; /* server encryption domain */ ulong cid; /* challenge id */ }; struct { Lock; Crypt *free; } cryptalloc; char eve[NAMELEN] = "bootes"; char evekey[DESKEYLEN]; char hostdomain[DOMLEN]; /* * return true if current user is eve */ int iseve(void) { return strcmp(eve, u->p->user) == 0; } /* * crypt entries are allocated from a pool rather than allocated using malloc so * the memory can be protected from reading by devproc. The base and top of the * crypt arena is stored in palloc for devproc. */ Crypt* newcrypt(void) { Crypt *c; lock(&cryptalloc); if(cryptalloc.free) { c = cryptalloc.free; cryptalloc.free = c->next; unlock(&cryptalloc); memset(c, 0, sizeof(Crypt)); return c; } cryptalloc.free = xalloc(sizeof(Crypt)*conf.nproc); if(cryptalloc.free == 0) panic("newcrypt"); for(c = cryptalloc.free; c < cryptalloc.free+conf.nproc-1; c++) c->next = c+1; palloc.cmembase = (ulong)cryptalloc.free; palloc.cmemtop = palloc.cmembase+(sizeof(Crypt)*conf.nproc); unlock(&cryptalloc); return newcrypt(); } void freecrypt(Crypt *c) { lock(&cryptalloc); c->next = cryptalloc.free; cryptalloc.free = c; unlock(&cryptalloc); } /* * return the info received in the session message on this channel. * if no session message has been exchanged, do it. */ long sysfsession(ulong *arg) { int i, n; Chan *c; Fcall *f; char *buf; Crypt *cp; Session *s; Ticketreq tr; validaddr(arg[1], TICKREQLEN, 1); f = malloc(sizeof(Fcall)); if(f == 0) error(Enomem); buf = malloc(MAXMSG); if(buf == 0){ free(f); error(Enomem); } c = fdtochan(arg[0], OWRITE, 0, 1); s = 0; if(waserror()) { if(s) free(s); close(c); free(buf); free(f); nexterror(); } s = c->session; if(s == 0){ /* exchange a session message with the server */ s = malloc(sizeof(Session)); if(s == 0) error(Enomem); memset(s, 0, sizeof(Session)); for(i = 0; i < CHALLEN; i++) s->cchal[i] = nrand(256); f->type = Tsession; memmove(f->chal, s->cchal, CHALLEN); n = convS2M(f, buf); if((*devtab[c->type].write)(c, buf, n, 0) != n) error(Emountrpc); n = (*devtab[c->type].read)(c, buf, MAXMSG, 0); if(convM2S(buf, f, n) == 0) error(Emountrpc); if(f->type == Rsession){ memmove(s->schal, f->chal, CHALLEN); memmove(s->authid, f->authid, NAMELEN); memmove(s->authdom, f->authdom, DOMLEN); } s->cid = 0; c->session = s; } /* * If server requires no ticket, or user is "none", or a ticket * is already cached, zero the request type */ tr.type = AuthTreq; if(strcmp(u->p->user, "none") == 0 || c->session->authid[0] == 0) tr.type = 0; else for(cp = s->cache; cp; cp = cp->next) if(strcmp(cp->t.cuid, u->p->user) == 0){ tr.type = 0; break; } /* create ticket request */ memmove(tr.chal, c->session->schal, CHALLEN); memmove(tr.authid, c->session->authid, NAMELEN); memmove(tr.authdom, c->session->authdom, DOMLEN); memmove(tr.uid, u->p->user, NAMELEN); memmove(tr.hostid, eve, NAMELEN); convTR2M(&tr, (char*)arg[1]); poperror(); close(c); free(buf); free(f); return 0; } /* * attach tickets to a session */ long sysfauth(ulong *arg) { Chan *c; char *ta; Session *s; Crypt *cp, *ncp, **l; char tbuf[2*TICKETLEN]; validaddr(arg[1], 2*TICKETLEN, 0); c = fdtochan(arg[0], OWRITE, 0, 1); s = c->session; if(s == 0) error("fauth must follow fsession"); cp = newcrypt(); if(waserror()){ freecrypt(cp); nexterror(); } /* ticket supplied, use it */ ta = (char*)arg[1]; memmove(tbuf, ta, 2*TICKETLEN); convM2T(tbuf, &cp->t, evekey); if(cp->t.num != AuthTc) error("bad AuthTc in ticket"); if(strncmp(u->p->user, cp->t.cuid, NAMELEN) != 0) error("bad uid in ticket"); if(memcmp(cp->t.chal, s->schal, CHALLEN) != 0) error("bad chal in ticket"); memmove(cp->tbuf, tbuf+TICKETLEN, TICKETLEN); /* string onto local list, replace old version */ lock(s); l = &s->cache; for(ncp = s->cache; ncp; ncp = *l){ if(strcmp(ncp->t.cuid, u->p->user) == 0){ *l = ncp->next; freecrypt(ncp); break; } l = &ncp->next; } cp->next = s->cache; s->cache = cp; unlock(s); poperror(); return 0; } /* * free a session created by fsession */ void freesession(Session *s) { Crypt *cp; for(cp = s->cache; cp; cp = cp->next) freecrypt(cp); free(s); } /* * called by mattach() to fill in the Tattach message */ ulong authrequest(Session *s, Fcall *f) { Crypt *cp; ulong id, dofree; /* no authentication if user is "none" or if no ticket required by remote */ if(s == 0 || s->authid[0] == 0 || strcmp(u->p->user, "none") == 0){ memset(f->ticket, 0, TICKETLEN); memset(f->auth, 0, AUTHENTLEN); return 0; } /* look for ticket in cache */ dofree = 0; for(cp = s->cache; cp; cp = cp->next) if(strcmp(cp->t.cuid, u->p->user) == 0) break; if(cp == 0){ /* * create a ticket using hostkey, this solves the * chicken and egg problem */ cp = newcrypt(); cp->t.num = AuthTs; memmove(cp->t.chal, s->schal, CHALLEN); memmove(cp->t.cuid, u->p->user, NAMELEN); memmove(cp->t.suid, u->p->user, NAMELEN); memmove(cp->t.key, evekey, DESKEYLEN); convT2M(&cp->t, f->ticket, evekey); dofree = 1; } else memmove(f->ticket, cp->tbuf, TICKETLEN); lock(s); id = s->cid++; unlock(s); /* create an authenticator */ memmove(cp->a.chal, s->schal, CHALLEN); cp->a.num = AuthAc; cp->a.id = id; convA2M(&cp->a, f->auth, cp->t.key); if(dofree) freecrypt(cp); return id; } /* * called by mattach() to check the Rattach message */ void authreply(Session *s, ulong id, Fcall *f) { Crypt *cp; if(s == 0) return; for(cp = s->cache; cp; cp = cp->next) if(strcmp(cp->t.cuid, u->p->user) == 0) break; /* we're getting around authentication */ if(s == 0 || cp == 0 || s->authid[0] == 0 || strcmp(u->p->user, "none") == 0) return; convM2A(f->rauth, &cp->a, cp->t.key); if(cp->a.num != AuthAs){ print("bad encryption type\n"); error("server lies"); } if(memcmp(cp->a.chal, s->cchal, sizeof(cp->a.chal))){ print("bad returned challenge\n"); error("server lies"); } if(cp->a.id != id){ print("bad returned id\n"); error("server lies"); } } /* * called by devcons() for #c/authenticate * * The protocol is * 1) read ticket request from #c/authenticate * 2) write ticket to #c/authenticate. if it matchs the challenge the * user is changed to the suid field of the ticket * 3) read authenticator (to confirm this is the server advertised) */ long authread(Chan *c, char *a, int n) { Crypt *cp; int i; Ticketreq tr; if(c->aux == 0){ /* * first read returns a ticket request */ if(n != TICKREQLEN) error(Ebadarg); c->aux = newcrypt(); cp = c->aux; memset(&tr, 0, sizeof(tr)); tr.type = AuthTreq; strcpy(tr.hostid, eve); strcpy(tr.authid, eve); strcpy(tr.authdom, hostdomain); strcpy(tr.uid, u->p->user); for(i = 0; i < CHALLEN; i++) tr.chal[i] = nrand(256); memmove(cp->a.chal, tr.chal, CHALLEN); convTR2M(&tr, a); } else { /* * subsequent read returns an authenticator */ if(n != AUTHENTLEN) error(Ebadarg); cp = c->aux; cp->a.num = AuthAs; memmove(cp->a.chal, cp->t.chal, CHALLEN); cp->a.id = 0; convA2M(&cp->a, a, cp->t.key); freecrypt(cp); c->aux = 0; } return n; } long authwrite(Chan *c, char *a, int n) { Crypt *cp; if(n != TICKETLEN) error(Ebadarg); if(c->aux == 0) error(Ebadarg); cp = c->aux; convM2T(a, &cp->t, evekey); if(cp->t.num != AuthTs || memcmp(cp->a.chal, cp->t.chal, CHALLEN)) error(Eperm); memmove(u->p->user, cp->t.suid, NAMELEN); return n; } /* * called by devcons() for #c/authcheck * * a write of a ticket+authenticator succeeds if they match */ long authcheck(Chan *c, char *a, int n) { Crypt *cp; if(n != TICKETLEN+AUTHENTLEN) error(Ebadarg); if(c->aux == 0) c->aux = newcrypt(); cp = c->aux; convM2T(a, &cp->t, evekey); if(cp->t.num != AuthTc || strcmp(u->p->user, cp->t.cuid)) error(Ebadarg); convM2A(a+TICKETLEN, &cp->a, cp->t.key); if(cp->a.num != AuthAs || memcmp(cp->t.chal, cp->a.chal, CHALLEN)) error(Eperm); return n; } void authclose(Chan *c) { if(c->aux) freecrypt(c->aux); c->aux = 0; } /* * called by devcons() for key device */ long keyread(char *a, int n, long offset) { if(n<DESKEYLEN || offset != 0) error(Ebadarg); if(!iseve()) error(Eperm); memmove(a, evekey, DESKEYLEN); return DESKEYLEN; } long keywrite(char *a, int n) { if(n != DESKEYLEN) error(Ebadarg); if(!iseve()) error(Eperm); memmove(evekey, a, DESKEYLEN); return DESKEYLEN; } /* * called by devcons() for user device * * anyone can become none */ long userwrite(char *a, int n) { if(n >= NAMELEN) error(Ebadarg); if(strcmp(a, "none") != 0) error(Eperm); memset(u->p->user, 0, NAMELEN); strcpy(u->p->user, "none"); return n; } /* * called by devcons() for host owner/domain * * writing hostowner also sets user */ long hostownerwrite(char *a, int n) { char buf[NAMELEN]; if(!iseve()) error(Eperm); if(n >= NAMELEN) error(Ebadarg); memset(buf, 0, NAMELEN); strncpy(buf, a, n); if(buf[0] == 0) error(Ebadarg); memmove(eve, buf, NAMELEN); memmove(u->p->user, buf, NAMELEN); return n; } long hostdomainwrite(char *a, int n) { char buf[DOMLEN]; if(!iseve()) error(Eperm); if(n >= DOMLEN) error(Ebadarg); memset(buf, 0, DOMLEN); strncpy(buf, a, n); if(buf[0] == 0) error(Ebadarg); memmove(hostdomain, buf, DOMLEN); return n; }