--- /dev/null
+/*
+ * chap-new.c - New CHAP implementation.
+ *
+ * Copyright (c) 2003 Paul Mackerras. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in
+ * the documentation and/or other materials provided with the
+ * distribution.
+ *
+ * 3. The name(s) of the authors of this software must not be used to
+ * endorse or promote products derived from this software without
+ * prior written permission.
+ *
+ * 4. Redistributions of any form whatsoever must retain the following
+ * acknowledgment:
+ * "This product includes software developed by Paul Mackerras
+ * <paulus@samba.org>".
+ *
+ * THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
+ * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS, IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
+ * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
+ * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
+ * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#define RCSID "$Id"
+
+#include <stdlib.h>
+#include <string.h>
+#include "pppd.h"
+#include "chap-new.h"
+#include "chap-md5.h"
+
+#ifdef CHAPMS
+#include "chap_ms.h"
+#endif
+
+/* Hook for a plugin to validate CHAP challenge */
+int (*chap_verify_hook)(char *name, char *ourname, int id,
+ struct chap_digest_type *digest,
+ unsigned char *challenge, unsigned char *response,
+ unsigned char *message, int message_space) = NULL;
+
+/*
+ * Option variables.
+ */
+int chap_timeout_time = 3;
+int chap_max_transmits = 10;
+int chap_rechallenge_time = 0;
+
+/*
+ * Command-line options.
+ */
+static option_t chap_option_list[] = {
+ { "chap-restart", o_int, &chap_timeout_time,
+ "Set timeout for CHAP", OPT_PRIO },
+ { "chap-max-challenge", o_int, &chap_max_transmits,
+ "Set max #xmits for challenge", OPT_PRIO },
+ { "chap-interval", o_int, &chap_rechallenge_time,
+ "Set interval for rechallenge", OPT_PRIO },
+ { NULL }
+};
+
+/*
+ * Internal state.
+ */
+static struct chap_client_state {
+ int flags;
+ char *name;
+ struct chap_digest_type *digest;
+ unsigned char priv[64]; /* private area for digest's use */
+} client;
+
+/*
+ * These limits apply to challenge and response packets we send.
+ * The +4 is the +1 that we actually need rounded up.
+ */
+#define CHAL_MAX_PKTLEN (PPP_HDRLEN + CHAP_HDRLEN + 4 + MAX_CHALLENGE_LEN + MAXNAMELEN)
+#define RESP_MAX_PKTLEN (PPP_HDRLEN + CHAP_HDRLEN + 4 + MAX_RESPONSE_LEN + MAXNAMELEN)
+
+static struct chap_server_state {
+ int flags;
+ int id;
+ char *name;
+ struct chap_digest_type *digest;
+ int challenge_xmits;
+ int challenge_pktlen;
+ unsigned char challenge[CHAL_MAX_PKTLEN];
+} server;
+
+/* Values for flags in chap_client_state and chap_server_state */
+#define LOWERUP 1
+#define AUTH_STARTED 2
+#define AUTH_DONE 4
+#define AUTH_FAILED 8
+#define TIMEOUT_PENDING 0x10
+#define CHALLENGE_VALID 0x20
+
+/*
+ * Prototypes.
+ */
+static void chap_init(int unit);
+static void chap_lowerup(int unit);
+static void chap_lowerdown(int unit);
+static void chap_timeout(void *arg);
+static void chap_generate_challenge(struct chap_server_state *ss);
+static void chap_handle_response(struct chap_server_state *ss, int code,
+ unsigned char *pkt, int len);
+static int chap_verify_response(char *name, char *ourname, int id,
+ struct chap_digest_type *digest,
+ unsigned char *challenge, unsigned char *response,
+ unsigned char *message, int message_space);
+static void chap_respond(struct chap_client_state *cs, int id,
+ unsigned char *pkt, int len);
+static void chap_handle_status(struct chap_client_state *cs, int code, int id,
+ unsigned char *pkt, int len);
+static void chap_protrej(int unit);
+static void chap_input(int unit, unsigned char *pkt, int pktlen);
+static int chap_print_pkt(unsigned char *p, int plen,
+ void (*printer) __P((void *, char *, ...)), void *arg);
+
+/* List of digest types that we know about */
+static struct chap_digest_type *chap_digests;
+
+/*
+ * chap_init - reset to initial state.
+ */
+static void
+chap_init(int unit)
+{
+ memset(&client, 0, sizeof(client));
+ memset(&server, 0, sizeof(server));
+
+ chap_md5_init();
+#ifdef CHAPMS
+ chapms_init();
+#endif
+}
+
+/*
+ * Add a new digest type to the list.
+ */
+void
+chap_register_digest(struct chap_digest_type *dp)
+{
+ dp->next = chap_digests;
+ chap_digests = dp;
+}
+
+/*
+ * chap_lowerup - we can start doing stuff now.
+ */
+static void
+chap_lowerup(int unit)
+{
+ struct chap_client_state *cs = &client;
+ struct chap_server_state *ss = &server;
+
+ cs->flags |= LOWERUP;
+ ss->flags |= LOWERUP;
+ if (ss->flags & AUTH_STARTED)
+ chap_timeout(ss);
+}
+
+static void
+chap_lowerdown(int unit)
+{
+ struct chap_client_state *cs = &client;
+ struct chap_server_state *ss = &server;
+
+ cs->flags = 0;
+ if (ss->flags & TIMEOUT_PENDING)
+ UNTIMEOUT(chap_timeout, ss);
+ ss->flags = 0;
+}
+
+/*
+ * chap_auth_peer - Start authenticating the peer.
+ * If the lower layer is already up, we start sending challenges,
+ * otherwise we wait for the lower layer to come up.
+ */
+void
+chap_auth_peer(int unit, char *our_name, int digest_code)
+{
+ struct chap_server_state *ss = &server;
+ struct chap_digest_type *dp;
+
+ if (ss->flags & AUTH_STARTED) {
+ error("CHAP: peer authentication already started!");
+ return;
+ }
+ for (dp = chap_digests; dp != NULL; dp = dp->next)
+ if (dp->code == digest_code)
+ break;
+ if (dp == NULL)
+ fatal("CHAP digest 0x%x requested but not available",
+ digest_code);
+
+ ss->digest = dp;
+ ss->name = our_name;
+ /* Start with a random ID value */
+ ss->id = (unsigned char)(drand48() * 256);
+ ss->flags |= AUTH_STARTED;
+ if (ss->flags & LOWERUP)
+ chap_timeout(ss);
+}
+
+/*
+ * chap_auth_peer - Prepare to authenticate ourselves to the peer.
+ * There isn't much to do until we receive a challenge.
+ */
+void
+chap_auth_with_peer(int unit, char *our_name, int digest_code)
+{
+ struct chap_client_state *cs = &client;
+ struct chap_digest_type *dp;
+
+ if (cs->flags & AUTH_STARTED) {
+ error("CHAP: authentication with peer already started!");
+ return;
+ }
+ for (dp = chap_digests; dp != NULL; dp = dp->next)
+ if (dp->code == digest_code)
+ break;
+ if (dp == NULL)
+ fatal("CHAP digest 0x%x requested but not available",
+ digest_code);
+
+ cs->digest = dp;
+ cs->name = our_name;
+ cs->flags |= AUTH_STARTED;
+}
+
+/*
+ * chap_timeout - It's time to send another challenge to the peer.
+ * This could be either a retransmission of a previous challenge,
+ * or a new challenge to start re-authentication.
+ */
+static void
+chap_timeout(void *arg)
+{
+ struct chap_server_state *ss = arg;
+
+ ss->flags &= ~TIMEOUT_PENDING;
+ if ((ss->flags & CHALLENGE_VALID) == 0) {
+ ss->challenge_xmits = 0;
+ chap_generate_challenge(ss);
+ ss->flags |= CHALLENGE_VALID;
+ } else if (ss->challenge_xmits >= chap_max_transmits) {
+ ss->flags &= ~CHALLENGE_VALID;
+ ss->flags |= AUTH_DONE | AUTH_FAILED;
+ auth_peer_fail(0, PPP_CHAP);
+ return;
+ }
+
+ output(0, ss->challenge, ss->challenge_pktlen);
+ ++ss->challenge_xmits;
+ ss->flags |= TIMEOUT_PENDING;
+ TIMEOUT(chap_timeout, arg, chap_timeout_time);
+}
+
+/*
+ * chap_generate_challenge - generate a challenge string and format
+ * the challenge packet in ss->challenge_pkt.
+ */
+static void
+chap_generate_challenge(struct chap_server_state *ss)
+{
+ int clen = 1, nlen, len;
+ unsigned char *p;
+
+ p = ss->challenge;
+ MAKEHEADER(p, PPP_CHAP);
+ p += CHAP_HDRLEN;
+ ss->digest->generate_challenge(p);
+ clen = *p;
+ nlen = strlen(ss->name);
+ memcpy(p + 1 + clen, ss->name, nlen);
+
+ len = CHAP_HDRLEN + 1 + clen + nlen;
+ ss->challenge_pktlen = PPP_HDRLEN + len;
+
+ p = ss->challenge + PPP_HDRLEN;
+ p[0] = CHAP_CHALLENGE;
+ p[1] = ++ss->id;
+ p[2] = len >> 8;
+ p[3] = len;
+}
+
+/*
+ * chap_handle_response - check the response to our challenge.
+ */
+static void
+chap_handle_response(struct chap_server_state *ss, int id,
+ unsigned char *pkt, int len)
+{
+ int response_len, ok, mlen;
+ unsigned char *response, *p;
+ unsigned char *name = NULL; /* initialized to shut gcc up */
+ int (*verifier)(char *, char *, int, struct chap_digest_type *,
+ unsigned char *, unsigned char *, unsigned char *, int);
+ char rname[MAXNAMELEN+1];
+ unsigned char message[256];
+
+ if ((ss->flags & LOWERUP) == 0)
+ return;
+ if (id != ss->challenge[PPP_HDRLEN+1] || len < 2)
+ return;
+ if ((ss->flags & AUTH_DONE) == 0) {
+ if ((ss->flags & CHALLENGE_VALID) == 0)
+ return;
+ response = pkt;
+ GETCHAR(response_len, pkt);
+ len -= response_len + 1; /* length of name */
+ name = pkt + response_len;
+ if (len < 0)
+ return;
+
+ ss->flags &= ~CHALLENGE_VALID;
+ if (ss->flags & TIMEOUT_PENDING) {
+ ss->flags &= ~TIMEOUT_PENDING;
+ UNTIMEOUT(chap_timeout, ss);
+ }
+
+ if (explicit_remote) {
+ name = remote_name;
+ } else {
+ /* Null terminate and clean remote name. */
+ slprintf(rname, sizeof(rname), "%.*v", len, name);
+ name = rname;
+ }
+
+ if (chap_verify_hook)
+ verifier = chap_verify_hook;
+ else
+ verifier = chap_verify_response;
+ ok = (*verifier)(name, ss->name, id, ss->digest,
+ ss->challenge + PPP_HDRLEN + CHAP_HDRLEN,
+ response, message, sizeof(message));
+ if (!ok || !auth_number()) {
+ ss->flags |= AUTH_FAILED;
+ warn("Peer %q failed CHAP authentication", name);
+ }
+ }
+
+ /* send the response */
+ p = outpacket_buf;
+ MAKEHEADER(p, PPP_CHAP);
+ mlen = strlen(message);
+ len = CHAP_HDRLEN + mlen;
+ p[0] = (ss->flags & AUTH_FAILED)? CHAP_FAILURE: CHAP_SUCCESS;
+ p[1] = id;
+ p[2] = len >> 8;
+ p[3] = len;
+ if (mlen > 0)
+ memcpy(p + CHAP_HDRLEN, message, mlen);
+ output(0, outpacket_buf, PPP_HDRLEN + len);
+
+ if ((ss->flags & AUTH_DONE) == 0) {
+ ss->flags |= AUTH_DONE;
+ if (ss->flags & AUTH_FAILED) {
+ auth_peer_fail(0, PPP_CHAP);
+ } else {
+ auth_peer_success(0, PPP_CHAP, ss->digest->code,
+ name, strlen(name));
+ if (chap_rechallenge_time) {
+ ss->flags |= TIMEOUT_PENDING;
+ TIMEOUT(chap_timeout, ss,
+ chap_rechallenge_time);
+ }
+ }
+ }
+}
+
+/*
+ * chap_verify_response - check whether the peer's response matches
+ * what we think it should be. Returns 1 if it does (authentication
+ * succeeded), or 0 if it doesn't.
+ */
+static int
+chap_verify_response(char *name, char *ourname, int id,
+ struct chap_digest_type *digest,
+ unsigned char *challenge, unsigned char *response,
+ unsigned char *message, int message_space)
+{
+ int ok;
+ char secret[MAXSECRETLEN];
+ int secret_len;
+
+ /* Get the secret that the peer is supposed to know */
+ if (!get_secret(0, name, ourname, secret, &secret_len, 1)) {
+ error("No CHAP secret found for authenticating %q", name);
+ return 0;
+ }
+
+ ok = digest->verify_response(id, name, secret, secret_len, challenge,
+ response, message, message_space);
+ memset(secret, 0, sizeof(secret));
+
+ return ok;
+}
+
+/*
+ * chap_respond - Generate and send a response to a challenge.
+ */
+static void
+chap_respond(struct chap_client_state *cs, int id,
+ unsigned char *pkt, int len)
+{
+ int clen, nlen;
+ int secret_len;
+ unsigned char *p;
+ unsigned char response[RESP_MAX_PKTLEN];
+ char rname[MAXNAMELEN+1];
+ char secret[MAXSECRETLEN+1];
+
+ if ((cs->flags & (LOWERUP | AUTH_STARTED)) != (LOWERUP | AUTH_STARTED))
+ return; /* not ready */
+ if (len < 2 || len < pkt[0] + 1)
+ return; /* too short */
+ clen = pkt[0];
+ nlen = len - (clen + 1);
+
+ /* Null terminate and clean remote name. */
+ slprintf(rname, sizeof(rname), "%.*v", nlen, pkt + clen + 1);
+
+ /* Microsoft doesn't send their name back in the PPP packet */
+ if (explicit_remote || (remote_name[0] != 0 && rname[0] == 0))
+ strlcpy(rname, remote_name, sizeof(rname));
+
+ /* get secret for authenticating ourselves with the specified host */
+ if (!get_secret(0, cs->name, rname, secret, &secret_len, 0)) {
+ secret_len = 0; /* assume null secret if can't find one */
+ warn("No CHAP secret found for authenticating us to %q", rname);
+ }
+
+ p = response;
+ MAKEHEADER(p, PPP_CHAP);
+ p += CHAP_HDRLEN;
+
+ cs->digest->make_response(p, id, cs->name, pkt,
+ secret, secret_len, cs->priv);
+ memset(secret, 0, secret_len);
+
+ clen = *p;
+ nlen = strlen(cs->name);
+ memcpy(p + clen + 1, cs->name, nlen);
+
+ p = response + PPP_HDRLEN;
+ len = CHAP_HDRLEN + clen + 1 + nlen;
+ p[0] = CHAP_RESPONSE;
+ p[1] = id;
+ p[2] = len >> 8;
+ p[3] = len;
+
+ output(0, response, PPP_HDRLEN + len);
+}
+
+static void
+chap_handle_status(struct chap_client_state *cs, int code, int id,
+ unsigned char *pkt, int len)
+{
+ const char *msg = NULL;
+
+ if ((cs->flags & (AUTH_DONE|AUTH_STARTED|LOWERUP))
+ != (AUTH_STARTED|LOWERUP))
+ return;
+ cs->flags |= AUTH_DONE;
+
+ if (code == CHAP_SUCCESS) {
+ /* used for MS-CHAP v2 mutual auth, yuck */
+ if (cs->digest->check_success != NULL) {
+ if (!(*cs->digest->check_success)(pkt, len, cs->priv))
+ code = CHAP_FAILURE;
+ } else
+ msg = "CHAP authentication succeeded";
+ } else {
+ if (cs->digest->handle_failure != NULL)
+ (*cs->digest->handle_failure)(pkt, len);
+ else
+ msg = "CHAP authentication failed";
+ }
+ if (msg) {
+ if (len > 0)
+ info("%s: %.*v", msg, len, pkt);
+ else
+ info("%s", msg);
+ }
+ if (code == CHAP_SUCCESS)
+ auth_withpeer_success(0, PPP_CHAP, cs->digest->code);
+ else {
+ cs->flags |= AUTH_FAILED;
+ auth_withpeer_fail(0, PPP_CHAP);
+ }
+}
+
+static void
+chap_input(int unit, unsigned char *pkt, int pktlen)
+{
+ struct chap_client_state *cs = &client;
+ struct chap_server_state *ss = &server;
+ unsigned char code, id;
+ int len;
+
+ if (pktlen < CHAP_HDRLEN)
+ return;
+ GETCHAR(code, pkt);
+ GETCHAR(id, pkt);
+ GETSHORT(len, pkt);
+ if (len < CHAP_HDRLEN || len > pktlen)
+ return;
+ len -= CHAP_HDRLEN;
+
+ switch (code) {
+ case CHAP_CHALLENGE:
+ chap_respond(cs, id, pkt, len);
+ break;
+ case CHAP_RESPONSE:
+ chap_handle_response(ss, id, pkt, len);
+ break;
+ case CHAP_FAILURE:
+ case CHAP_SUCCESS:
+ chap_handle_status(cs, code, id, pkt, len);
+ break;
+ }
+}
+
+static void
+chap_protrej(int unit)
+{
+ struct chap_client_state *cs = &client;
+ struct chap_server_state *ss = &server;
+
+ if (ss->flags & TIMEOUT_PENDING) {
+ ss->flags &= ~TIMEOUT_PENDING;
+ UNTIMEOUT(chap_timeout, ss);
+ }
+ if (ss->flags & AUTH_STARTED) {
+ ss->flags = 0;
+ auth_peer_fail(0, PPP_CHAP);
+ }
+ if ((cs->flags & (AUTH_STARTED|AUTH_DONE)) == AUTH_STARTED) {
+ cs->flags &= ~AUTH_STARTED;
+ auth_withpeer_fail(0, PPP_CHAP);
+ }
+}
+
+/*
+ * chap_print_pkt - print the contents of a CHAP packet.
+ */
+static char *chap_code_names[] = {
+ "Challenge", "Response", "Success", "Failure"
+};
+
+static int
+chap_print_pkt(unsigned char *p, int plen,
+ void (*printer) __P((void *, char *, ...)), void *arg)
+{
+ int code, id, len;
+ int clen, nlen;
+ unsigned char x;
+
+ if (plen < CHAP_HDRLEN)
+ return 0;
+ GETCHAR(code, p);
+ GETCHAR(id, p);
+ GETSHORT(len, p);
+ if (len < CHAP_HDRLEN || len > plen)
+ return 0;
+
+ if (code >= 1 && code <= sizeof(chap_code_names) / sizeof(char *))
+ printer(arg, " %s", chap_code_names[code-1]);
+ else
+ printer(arg, " code=0x%x", code);
+ printer(arg, " id=0x%x", id);
+ len -= CHAP_HDRLEN;
+ switch (code) {
+ case CHAP_CHALLENGE:
+ case CHAP_RESPONSE:
+ if (len < 1)
+ break;
+ clen = p[0];
+ if (len < clen + 1)
+ break;
+ ++p;
+ nlen = len - clen - 1;
+ printer(arg, " <");
+ for (; clen > 0; --clen) {
+ GETCHAR(x, p);
+ printer(arg, "%.2x", x);
+ }
+ printer(arg, ">, name = ");
+ print_string((char *)p, nlen, printer, arg);
+ break;
+ case CHAP_FAILURE:
+ case CHAP_SUCCESS:
+ printer(arg, " ");
+ print_string((char *)p, len, printer, arg);
+ break;
+ default:
+ for (clen = len; clen > 0; --clen) {
+ GETCHAR(x, p);
+ printer(arg, " %.2x", x);
+ }
+ }
+
+ return len + CHAP_HDRLEN;
+}
+
+struct protent chap_protent = {
+ PPP_CHAP,
+ chap_init,
+ chap_input,
+ chap_protrej,
+ chap_lowerup,
+ chap_lowerdown,
+ NULL, /* open */
+ NULL, /* close */
+ chap_print_pkt,
+ NULL, /* datainput */
+ 1, /* enabled_flag */
+ "CHAP", /* name */
+ NULL, /* data_name */
+ chap_option_list,
+ NULL, /* check_options */
+};
projects / ppp.git / blobdiff