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- /*
- * This file is part of the UCB release of Plan 9. It is subject to the license
- * terms in the LICENSE file found in the top-level directory of this
- * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No
- * part of the UCB release of Plan 9, including this file, may be copied,
- * modified, propagated, or distributed except according to the terms contained
- * in the LICENSE file.
- */
- /*
- * CHAP, MSCHAP
- *
- * The client does not authenticate the server, hence no CAI
- *
- * Client protocol:
- * write Chapchal
- * read response Chapreply or MSchaprely structure
- *
- * Server protocol:
- * read challenge: 8 bytes binary
- * write user: utf8
- * write response: Chapreply or MSchapreply structure
- */
- #include <ctype.h>
- #include "dat.h"
- enum {
- ChapChallen = 8,
- ChapResplen = 16,
- MSchapResplen = 24,
- };
- static int dochal(State*);
- static int doreply(State*, void*, int);
- static void doLMchap(char *, uint8_t [ChapChallen],
- uint8_t [MSchapResplen]);
- static void doNTchap(char *, uint8_t [ChapChallen],
- uint8_t [MSchapResplen]);
- static void dochap(char *, int, char [ChapChallen],
- uint8_t [ChapResplen]);
- struct State
- {
- char *protoname;
- int astype;
- int asfd;
- Key *key;
- Ticket t;
- Ticketreq tr;
- char chal[ChapChallen];
- MSchapreply mcr;
- char cr[ChapResplen];
- char err[ERRMAX];
- char user[64];
- uint8_t secret[16]; /* for mschap */
- int nsecret;
- };
- enum
- {
- CNeedChal,
- CHaveResp,
- SHaveChal,
- SNeedUser,
- SNeedResp,
- SHaveZero,
- SHaveCAI,
- Maxphase
- };
- static char *phasenames[Maxphase] =
- {
- [CNeedChal] = "CNeedChal",
- [CHaveResp] = "CHaveResp",
- [SHaveChal] = "SHaveChal",
- [SNeedUser] = "SNeedUser",
- [SNeedResp] = "SNeedResp",
- [SHaveZero] = "SHaveZero",
- [SHaveCAI] = "SHaveCAI",
- };
- static int
- chapinit(Proto *p, Fsstate *fss)
- {
- int iscli, ret;
- State *s;
- if((iscli = isclient(_strfindattr(fss->attr, "role"))) < 0)
- return failure(fss, nil);
- s = emalloc(sizeof *s);
- fss->phasename = phasenames;
- fss->maxphase = Maxphase;
- s->asfd = -1;
- if(p == &chap){
- s->astype = AuthChap;
- s->protoname = "chap";
- }else{
- s->astype = AuthMSchap;
- s->protoname = "mschap";
- }
- if(iscli)
- fss->phase = CNeedChal;
- else{
- if((ret = findp9authkey(&s->key, fss)) != RpcOk){
- free(s);
- return ret;
- }
- if(dochal(s) < 0){
- free(s);
- return failure(fss, nil);
- }
- fss->phase = SHaveChal;
- }
- fss->ps = s;
- return RpcOk;
- }
- static void
- chapclose(Fsstate *fss)
- {
- State *s;
- s = fss->ps;
- if(s->asfd >= 0){
- close(s->asfd);
- s->asfd = -1;
- }
- free(s);
- }
- static int
- chapwrite(Fsstate *fss, void *va, uint n)
- {
- int ret, nreply;
- char *a, *v;
- void *reply;
- Key *k;
- Keyinfo ki;
- State *s;
- Chapreply cr;
- MSchapreply mcr;
- OChapreply ocr;
- OMSchapreply omcr;
- s = fss->ps;
- a = va;
- switch(fss->phase){
- default:
- return phaseerror(fss, "write");
- case CNeedChal:
- ret = findkey(&k, mkkeyinfo(&ki, fss, nil), "%s", fss->proto->keyprompt);
- if(ret != RpcOk)
- return ret;
- v = _strfindattr(k->privattr, "!password");
- if(v == nil)
- return failure(fss, "key has no password");
- setattrs(fss->attr, k->attr);
- switch(s->astype){
- default:
- abort();
- case AuthMSchap:
- doLMchap(v, (uint8_t *)a, (uint8_t *)s->mcr.LMresp);
- doNTchap(v, (uint8_t *)a, (uint8_t *)s->mcr.NTresp);
- break;
- case AuthChap:
- dochap(v, *a, a+1, (uint8_t *)s->cr);
- break;
- }
- closekey(k);
- fss->phase = CHaveResp;
- return RpcOk;
- case SNeedUser:
- if(n >= sizeof s->user)
- return failure(fss, "user name too long");
- memmove(s->user, va, n);
- s->user[n] = '\0';
- fss->phase = SNeedResp;
- return RpcOk;
- case SNeedResp:
- switch(s->astype){
- default:
- return failure(fss, "chap internal botch");
- case AuthChap:
- if(n != sizeof(Chapreply))
- return failure(fss, "did not get Chapreply");
- memmove(&cr, va, sizeof cr);
- ocr.id = cr.id;
- memmove(ocr.resp, cr.resp, sizeof ocr.resp);
- memset(omcr.uid, 0, sizeof(omcr.uid));
- strecpy(ocr.uid, ocr.uid+sizeof ocr.uid, s->user);
- reply = &ocr;
- nreply = sizeof ocr;
- break;
- case AuthMSchap:
- if(n != sizeof(MSchapreply))
- return failure(fss, "did not get MSchapreply");
- memmove(&mcr, va, sizeof mcr);
- memmove(omcr.LMresp, mcr.LMresp, sizeof omcr.LMresp);
- memmove(omcr.NTresp, mcr.NTresp, sizeof omcr.NTresp);
- memset(omcr.uid, 0, sizeof(omcr.uid));
- strecpy(omcr.uid, omcr.uid+sizeof omcr.uid, s->user);
- reply = &omcr;
- nreply = sizeof omcr;
- break;
- }
- if(doreply(s, reply, nreply) < 0)
- return failure(fss, nil);
- fss->phase = Established;
- fss->ai.cuid = s->t.cuid;
- fss->ai.suid = s->t.suid;
- fss->ai.secret = s->secret;
- fss->ai.nsecret = s->nsecret;
- fss->haveai = 1;
- return RpcOk;
- }
- }
- static int
- chapread(Fsstate *fss, void *va, uint *n)
- {
- State *s;
- s = fss->ps;
- switch(fss->phase){
- default:
- return phaseerror(fss, "read");
- case CHaveResp:
- switch(s->astype){
- default:
- phaseerror(fss, "write");
- break;
- case AuthMSchap:
- if(*n > sizeof(MSchapreply))
- *n = sizeof(MSchapreply);
- memmove(va, &s->mcr, *n);
- break;
- case AuthChap:
- if(*n > ChapResplen)
- *n = ChapResplen;
- memmove(va, s->cr, ChapResplen);
- break;
- }
- fss->phase = Established;
- fss->haveai = 0;
- return RpcOk;
- case SHaveChal:
- if(*n > sizeof s->chal)
- *n = sizeof s->chal;
- memmove(va, s->chal, *n);
- fss->phase = SNeedUser;
- return RpcOk;
- }
- }
- static int
- dochal(State *s)
- {
- char *dom, *user;
- char trbuf[TICKREQLEN];
- s->asfd = -1;
- /* send request to authentication server and get challenge */
- if((dom = _strfindattr(s->key->attr, "dom")) == nil
- || (user = _strfindattr(s->key->attr, "user")) == nil){
- werrstr("chap/dochal cannot happen");
- goto err;
- }
- s->asfd = _authdial(nil, dom);
- if(s->asfd < 0)
- goto err;
- memset(&s->tr, 0, sizeof(s->tr));
- s->tr.type = s->astype;
- safecpy(s->tr.authdom, dom, sizeof s->tr.authdom);
- safecpy(s->tr.hostid, user, sizeof(s->tr.hostid));
- convTR2M(&s->tr, trbuf);
- if(write(s->asfd, trbuf, TICKREQLEN) != TICKREQLEN)
- goto err;
- /* readn, not _asrdresp. needs to match auth.srv.c. */
- if(readn(s->asfd, s->chal, sizeof s->chal) != sizeof s->chal)
- goto err;
- return 0;
- err:
- if(s->asfd >= 0)
- close(s->asfd);
- s->asfd = -1;
- return -1;
- }
- static int
- doreply(State *s, void *reply, int nreply)
- {
- char ticket[TICKETLEN+AUTHENTLEN];
- int n;
- Authenticator a;
- if((n=write(s->asfd, reply, nreply)) != nreply){
- if(n >= 0)
- werrstr("short write to auth server");
- goto err;
- }
- if(_asrdresp(s->asfd, ticket, TICKETLEN+AUTHENTLEN) < 0){
- /* leave connection open so we can try again */
- return -1;
- }
- s->nsecret = readn(s->asfd, s->secret, sizeof s->secret);
- if(s->nsecret < 0)
- s->nsecret = 0;
- close(s->asfd);
- s->asfd = -1;
- convM2T(ticket, &s->t, s->key->priv);
- if(s->t.num != AuthTs
- || memcmp(s->t.chal, s->tr.chal, sizeof(s->t.chal)) != 0){
- if(s->key->successes == 0)
- disablekey(s->key);
- werrstr(Easproto);
- return -1;
- }
- s->key->successes++;
- convM2A(ticket+TICKETLEN, &a, s->t.key);
- if(a.num != AuthAc
- || memcmp(a.chal, s->tr.chal, sizeof(a.chal)) != 0
- || a.id != 0){
- werrstr(Easproto);
- return -1;
- }
- return 0;
- err:
- if(s->asfd >= 0)
- close(s->asfd);
- s->asfd = -1;
- return -1;
- }
- Proto chap = {
- .name= "chap",
- .init= chapinit,
- .write= chapwrite,
- .read= chapread,
- .close= chapclose,
- .addkey= replacekey,
- .keyprompt= "!password?"
- };
- Proto mschap = {
- .name= "mschap",
- .init= chapinit,
- .write= chapwrite,
- .read= chapread,
- .close= chapclose,
- .addkey= replacekey,
- .keyprompt= "!password?"
- };
- static void
- hash(uint8_t pass[16], uint8_t c8[ChapChallen], uint8_t p24[MSchapResplen])
- {
- int i;
- uint8_t p21[21];
- uint32_t schedule[32];
- memset(p21, 0, sizeof p21 );
- memmove(p21, pass, 16);
- for(i=0; i<3; i++) {
- key_setup(p21+i*7, schedule);
- memmove(p24+i*8, c8, 8);
- block_cipher(schedule, p24+i*8, 0);
- }
- }
- static void
- doNTchap(char *pass, uint8_t chal[ChapChallen],
- uint8_t reply[MSchapResplen])
- {
- Rune r;
- int i, n;
- uint8_t digest[MD4dlen];
- uint8_t *w, unipass[256];
- // Standard says unlimited length, experience says 128 max
- if ((n = strlen(pass)) > 128)
- n = 128;
- for(i=0, w=unipass; i < n; i++) {
- pass += chartorune(&r, pass);
- *w++ = r & 0xff;
- *w++ = r >> 8;
- }
- memset(digest, 0, sizeof digest);
- md4(unipass, w-unipass, digest, nil);
- memset(unipass, 0, sizeof unipass);
- hash(digest, chal, reply);
- }
- static void
- doLMchap(char *pass, uint8_t chal[ChapChallen],
- uint8_t reply[MSchapResplen])
- {
- int i;
- uint32_t schedule[32];
- uint8_t p14[15], p16[16];
- uint8_t s8[8] = {0x4b, 0x47, 0x53, 0x21, 0x40, 0x23, 0x24, 0x25};
- int n = strlen(pass);
- if(n > 14){
- // let prudent people avoid the LM vulnerability
- // and protect the loop below from buffer overflow
- memset(reply, 0, MSchapResplen);
- return;
- }
- // Spec says space padded, experience says otherwise
- memset(p14, 0, sizeof p14 -1);
- p14[sizeof p14 - 1] = '\0';
- // NT4 requires uppercase, Win XP doesn't care
- for (i = 0; pass[i]; i++)
- p14[i] = islower(pass[i])? toupper(pass[i]): pass[i];
- for(i=0; i<2; i++) {
- key_setup(p14+i*7, schedule);
- memmove(p16+i*8, s8, 8);
- block_cipher(schedule, p16+i*8, 0);
- }
- memset(p14, 0, sizeof p14);
- hash(p16, chal, reply);
- }
- static void
- dochap(char *pass, int id, char chal[ChapChallen],
- uint8_t resp[ChapResplen])
- {
- char buf[1+ChapChallen+MAXNAMELEN+1];
- int n = strlen(pass);
- *buf = id;
- if (n > MAXNAMELEN)
- n = MAXNAMELEN-1;
- memset(buf, 0, sizeof buf);
- strncpy(buf+1, pass, n);
- memmove(buf+1+n, chal, ChapChallen);
- md5((uint8_t*)buf, 1+n+ChapChallen, resp, nil);
- }
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