X-Git-Url: https://git.distorted.org.uk/~mdw/become/blobdiff_plain/c4f2d992e4a0fc068281376d89ec38de56dc2f58..b0f66028a9a17a845590a4fe737a4f5e46f6b778:/src/check.c diff --git a/src/check.c b/src/check.c index 9ed0b6f..ed561a7 100644 --- a/src/check.c +++ b/src/check.c @@ -1,13 +1,13 @@ /* -*-c-*- * - * $Id: check.c,v 1.1 1997/07/21 13:47:53 mdw Exp $ + * $Id: check.c,v 1.12 2003/11/29 23:39:16 mdw Exp $ * * Check validity of requests * - * (c) 1997 EBI + * (c) 1998 EBI */ -/*----- Licencing notice --------------------------------------------------* +/*----- Licensing notice --------------------------------------------------* * * This file is part of `become' * @@ -22,14 +22,56 @@ * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License - * along with `become'; if not, write to the Free Software - * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + * along with `become'; if not, write to the Free Software Foundation, + * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ /*----- Revision history --------------------------------------------------* * * $Log: check.c,v $ - * Revision 1.1 1997/07/21 13:47:53 mdw + * Revision 1.12 2003/11/29 23:39:16 mdw + * Debianization. + * + * Revision 1.11 2003/10/12 00:14:55 mdw + * Major overhaul. Now uses DSA signatures rather than the bogus symmetric + * encrypt-and-hope thing. Integrated with mLib and Catacomb. + * + * Revision 1.10 1999/05/04 16:17:12 mdw + * Change to header file name for parser. See log for `parse.h' for + * details. + * + * Revision 1.9 1998/06/19 13:48:16 mdw + * Set close-on-exec flag for UDP socket. + * + * Revision 1.8 1998/06/18 15:10:44 mdw + * SECURITY HOLE: the file descriptor for the secret key was left open and + * inherited by the target process. This is now fixed. Also set + * close-on-exec flags on key file, close config file carefully, and close + * UDP socket after receiving reply from server. + * + * Revision 1.7 1998/04/23 13:22:08 mdw + * Support no-network configuration option, and new interface to + * configuration file parser. + * + * Revision 1.6 1998/01/12 16:45:47 mdw + * Fix copyright date. + * + * Revision 1.5 1997/09/26 09:14:58 mdw + * Merged blowfish branch into trunk. + * + * Revision 1.4.2.1 1997/09/26 09:08:01 mdw + * Use the Blowfish encryption algorithm instead of IDEA. This is partly + * because I prefer Blowfish (without any particularly strong evidence) but + * mainly because IDEA is patented and Blowfish isn't. + * + * Revision 1.4 1997/08/07 09:52:05 mdw + * (Log entry for previous version is bogus.) Added support for multiple + * servers. + * + * Revision 1.2 1997/08/04 10:24:20 mdw + * Sources placed under CVS control. + * + * Revision 1.1 1997/07/21 13:47:53 mdw * Initial revision * */ @@ -55,176 +97,480 @@ #include +#include #include #include +/* --- mLib headers --- */ + +#include +#include +#include +#include +#include + +/* --- Catacomb headers --- */ + +#include +#include +#include +#include +#include +#include +#include + /* --- Local headers --- */ #include "become.h" #include "config.h" -#include "crypt.h" -#include "idea.h" #include "lexer.h" #include "name.h" +#include "netg.h" #include "rule.h" -#include "parser.h" -#include "tx.h" -#include "utils.h" +#include "parse.h" +#include "userdb.h" -/*----- Main code ---------------------------------------------------------*/ +/*----- Client-end network support ----------------------------------------*/ -/* --- @check__client@ --- * +#ifndef NONETWORK + +/* --- @check__send@ --- * + * + * Arguments: @char *buf@ = pointer to encrypted request + * @size_t sz@ = size of request + * @int fd@ = socket to send from + * @struct sockaddr_in *serv@ = pointer to table of servers + * @size_t n_serv@ = number of servers + * + * Returns: --- + * + * Use: Sends the request packet to the list of servers. If the + * message couldn't be sent to any of them, an error is + * reported. + */ + +static void check__send(char *buf, size_t sz, int fd, + struct sockaddr_in *serv, size_t n_serv) +{ + size_t i; + int ok = 0; + int err = 0; + + for (i = 0; i < n_serv; i++) { + if (sendto(fd, buf, sz, 0, + (struct sockaddr *)(serv + i), sizeof(serv[i])) < 0) { + T( trace(TRACE_CLIENT, "client: send to %s failed: %s", + inet_ntoa(serv[i].sin_addr), strerror(errno)); ) + err = errno; + } else + ok = 1; + } + + if (!ok) + die(1, "couldn't send request to server: %s", strerror(err)); +} + +/* --- @check__ask@ --- * * * Arguments: @request *rq@ = pointer to request buffer - * @const char *serv@ = pointer to the server - * @int port@ = port number to use + * @struct sockaddr_in *serv@ = pointer to table of servers + * @size_t n_serv@ = number of servers * * Returns: Nonzero if OK, zero if forbidden * - * Use: Contacts a server to decide whether the request is OK. + * Use: Contacts a number of servers to decide whether the request + * is OK. */ -static int check__client(request *rq, const char *serv, int port) +static int check__ask(request *rq, struct sockaddr_in *serv, size_t n_serv) { + static int tbl[] = { 0, 5, 10, 20, -1 }; + + char buff[2048], rbuff[2048]; + size_t rqlen; + octet hmsg[SHA_HASHSZ]; + octet h[SHA_HASHSZ]; + key_packstruct kps[DSA_PUBFETCHSZ]; + key_packdef *kp; + dsa_pub kpub; + buf b; + sha_ctx hc; int fd; - struct sockaddr_in ssin; - unsigned char crq[crq_size]; - unsigned char k[IDEA_KEYSIZE]; - unsigned char sk[IDEA_KEYSIZE]; - time_t t; - pid_t pid; + struct sockaddr_in sin; + socklen_t slen; + ssize_t sz; + int ans; + fd_set fds; + struct timeval start, now, tv; + mp *m, *r, *s; + key_file f; + key *k; + key_iter ki; + int ind; + size_t i; + + /* --- Open the public keyring --- */ + + if ((key_open(&f, file_PUBKEY, KOPEN_READ, key_moan, 0)) != 0) + die(1, "couldn't open public keyring"); + kp = key_fetchinit(dsa_pubfetch, kps, &kpub); + + /* --- Build the request packet --- */ + + rand_noisesrc(RAND_GLOBAL, &noise_source); + rand_seed(RAND_GLOBAL, 160); + buf_init(&b, buff, sizeof(buff)); + rand_get(RAND_GLOBAL, buf_get(&b, SHA_HASHSZ), SHA_HASHSZ); + buf_putu32(&b, rq->from); + buf_putu32(&b, rq->to); + buf_putu16(&b, strlen(rq->cmd)); + buf_put(&b, rq->cmd, strlen(rq->cmd)); + rqlen = BLEN(&b); + sha_init(&hc); + sha_hash(&hc, buff, rqlen); + sha_done(&hc, hmsg); /* --- Create my socket --- */ if ((fd = socket(PF_INET, SOCK_DGRAM, 0)) < 0) - die("couldn't create socket: %s", strerror(errno)); + die(1, "couldn't create socket: %s", strerror(errno)); + if (fcntl(fd, F_SETFD, 1) < 0) + die(1, "couldn't set close-on-exec flag for socket: %s", strerror(errno)); /* --- Bind myself to some address --- */ - { - struct sockaddr_in sin; - - sin.sin_family = AF_INET; - sin.sin_port = 0; - sin.sin_addr.s_addr = htonl(INADDR_ANY); + sin.sin_family = AF_INET; + sin.sin_port = 0; + sin.sin_addr.s_addr = htonl(INADDR_ANY); - if (bind(fd, (struct sockaddr *)&sin, sizeof(sin)) < 0) - die("couldn't bind socket to address: %s", strerror(errno)); - } + if (bind(fd, (struct sockaddr *)&sin, sizeof(sin)) < 0) + die(1, "couldn't bind socket to address: %s", strerror(errno)); - /* --- Find the server's address --- */ + /* --- Find out when we are --- */ - { - struct hostent *he; + gettimeofday(&start, 0); + ind = 0; - /* --- Resolve the server's name --- */ + /* --- Now loop until everything's done --- */ - if ((he = gethostbyname(serv)) == 0) - die("couldn't find server host `%s'", serv); + for (;;) { + gettimeofday(&now, 0); - /* --- Build the address block --- */ - - ssin.sin_family = AF_INET; - ssin.sin_port = htons(port); - memcpy(&ssin.sin_addr, he->h_addr, sizeof(struct in_addr)); - } + /* --- If the current timer has expired, find one that hasn't --- * + * + * Also resend the request after I've found a timer which is still + * extant. If there aren't any, report an error. + */ - /* --- Read in the encryption key --- */ - - { - FILE *fp; - - if ((fp = fopen(file_KEY, "r")) == 0) { - die("couldn't open key file `%s': %s", file_KEY, - strerror(errno)); + if (now.tv_sec >= start.tv_sec + tbl[ind] && + now.tv_usec >= start.tv_usec) { + do { + ind++; + if (tbl[ind] < 0) + die(1, "no reply from servers"); + } while (now.tv_sec >= start.tv_sec + tbl[ind] && + now.tv_usec >= start.tv_usec); + check__send(buff, rqlen, fd, serv, n_serv); + T( trace(TRACE_CLIENT, "client: send request to servers"); ) } - tx_getBits(k, 128, fp); - } - /* --- Now build a request packet --- */ + /* --- Now wait for a packet to arrive --- */ - t = time(0); - pid = getpid(); - crypt_packRequest(rq, crq, t, pid, k, sk); - - /* --- Send the packet to the server --- */ + if (now.tv_usec > start.tv_usec) { + now.tv_usec -= 1000000; + now.tv_sec += 1; + } + tv.tv_sec = start.tv_sec + tbl[ind] - now.tv_sec; + tv.tv_usec = start.tv_usec - now.tv_usec; + + /* --- Sort out file descriptors to watch --- */ + + FD_ZERO(&fds); + FD_SET(fd, &fds); + + /* --- Wait for them --- */ + + i = select(FD_SETSIZE, &fds, 0, 0, &tv); + if (i == 0 || (i < 0 && errno == EINTR)) + continue; + if (i < 0) + die(1, "error waiting for reply: %s", strerror(errno)); + + /* --- Read the reply data --- */ + + slen = sizeof(sin); + if ((sz = recvfrom(fd, (char *)rbuff, sizeof(rbuff), 0, + (struct sockaddr *)&sin, &slen)) < 0) + die(1, "error reading server's reply: %s", strerror(errno)); + + IF_TRACING(TRACE_CLIENT, { + struct hostent *h = gethostbyaddr((char *)&sin.sin_addr, + sizeof(sin.sin_addr), AF_INET); + trace(TRACE_CLIENT, "client: reply received from %s port %i", + h ? h->h_name : inet_ntoa(sin.sin_addr), + ntohs(sin.sin_port)); + }) + + /* --- Verify the sender --- * + * + * This is more to avoid confusion than for security: an active + * attacker is quite capable of forging the source address. We rely + * on the signature in the reply packet for authentication. + */ + + for (i = 0; i < n_serv; i++) { + if (sin.sin_addr.s_addr == serv[i].sin_addr.s_addr && + sin.sin_port == serv[i].sin_port) + break; + } + if (i >= n_serv) { + T( trace(TRACE_CLIENT, "client: reply from unknown host"); ) + continue; + } - if (sendto(fd, (char *)crq, sizeof(crq), 0, - (struct sockaddr *)&ssin, sizeof(ssin)) < 0) { - burn(k); - die("couldn't send request to server: %s", strerror(errno)); + /* --- Unpack and verify the response --- */ + + buf_init(&b, rbuff, sz); + if (buf_ensure(&b, sizeof(hmsg))) goto bad; + if (memcmp(BCUR(&b), hmsg, sizeof(hmsg)) != 0) goto bad; + BSTEP(&b, sizeof(hmsg)); + if ((ans = buf_getbyte(&b)) < 0) goto bad; + + sha_init(&hc); + sha_hash(&hc, BBASE(&b), BLEN(&b)); + sha_done(&hc, h); + if ((r = buf_getmp(&b)) == 0 || (s = buf_getmp(&b)) == 0) goto bad; + m = mp_loadb(MP_NEW, h, sizeof(h)); + + key_mkiter(&ki, &f); + while ((k = key_next(&ki)) != 0) { + if (key_expired(k)) continue; + if (strcmp(k->type, "become-dsa") != 0) continue; + if (key_fetch(kp, k)) continue; + i = dsa_vrfy(&kpub.dp, kpub.y, m, r, s); + dsa_pubfree(&kpub); + if (i) { + key_fetchdone(kp); + key_close(&f); + close(fd); + mp_drop(m); + mp_drop(r); + mp_drop(s); + return (ans); + } + } + + bad: + T( trace(TRACE_CLIENT, + "client: invalid or corrupt reply packet"); ) } - burn(k); - /* --- Now wait for a reply --- */ - - { - fd_set fds; - struct timeval when, now, tv; + die(1, "internal error: can't get here in check__ask"); + return (0); +} - gettimeofday(&when, 0); - when.tv_sec += 10; +/* --- @check__client@ --- * + * + * Arguments: @request *rq@ = pointer to a request block + * @FILE *fp@ = file containing server configuration + * + * Returns: Nonzero if OK, zero if forbidden + * + * Use: Asks one or several servers whether a request is acceptable. + */ - for (;;) { - int i; +int check__client(request *rq, FILE *fp) +{ + /* --- Format of the file --- * + * + * The `servers' file contains entries of the form + * + * %%\syntax{ [`:' ]}%% + * + * separates by whitespace. I build them all into an array of socket + * addresses and pass the whole lot to another function. + */ - /* --- Sort out when to return --- */ + struct sockaddr_in *serv; /* Array of servers */ + size_t n_serv, max_serv; /* Number and maximum number */ - gettimeofday(&now, 0); - if (now.tv_usec > when.tv_usec) { - now.tv_usec -= 1000000; - now.tv_sec += 1; - } - tv.tv_sec = when.tv_sec - now.tv_sec; - tv.tv_usec = when.tv_usec - now.tv_usec; + /* --- Initialise the server array --- */ - /* --- Sort out file descriptors to watch --- */ + T( trace(TRACE_CLIENT, "client: reading server definitions"); ) + n_serv = 0; max_serv = 4; /* Four seems reasonable */ + serv = xmalloc(sizeof(*serv) * max_serv); - FD_ZERO(&fds); - FD_SET(fd, &fds); + /* --- Start reading the file --- */ - /* --- Wait for them --- */ + { + char buff[256], *p, *l; /* A buffer and pointers for it */ + int port; /* Default port for servers */ + int state; /* Current parser state */ + struct in_addr t_host; /* Temp place for an address*/ + int t_port; /* Temp place for a port */ + int ch; /* The current character */ + + /* --- Parser states --- */ + + enum { + st_start, /* Waiting to begin */ + st_host, /* Reading a new hostname */ + st_colon, /* Expecting a colon, maybe */ + st_preport, /* Waiting before reading port */ + st_port, /* Reading a port number */ + st_commit, /* Commit a newly read server */ + st_done /* Finished reading the file */ + }; + + /* --- Find a default port --- */ + + { + struct servent *s = getservbyname(quis(), "udp"); + port = (s ? s->s_port : htons(SERVER_PORT)); + } - i = select(FD_SETSIZE, &fds, 0, 0, &tv); - if (i == 0) - die("no answer from server"); - if (i < 0) - die("error waiting for reply: %s", strerror(errno)); + /* --- Initialise for scanning the file --- */ - /* --- A reply should be waiting now --- */ + state = st_host; + p = buff; + l = buff + sizeof(buff); + t_port = port; + ch = getc(fp); - { - struct sockaddr_in sin; - int slen = sizeof(sin); - unsigned char buff[256]; - int answer; + /* --- Go for it --- */ + + while (state != st_done) { + switch (state) { + + /* --- Initial whitespace before hostname --- */ + + case st_start: + if (ch == EOF) + state = st_done; + else if (isspace((unsigned char)ch)) + ch = getc(fp); + else + state = st_host; + break; + + /* --- Read a host name --- */ + + case st_host: + if (p == l) + die(1, "string too long in `" file_SERVER "'"); + if (ch != EOF && !isspace((unsigned char)ch) && ch != ':') { + *p++ = ch; + ch = getc(fp); + } else { + struct hostent *h; + + *p++ = 0; + if ((h = gethostbyname(buff)) == 0) + die(1, "unknown host `%s' in `" file_SERVER "'", buff); + memcpy(&t_host, h->h_addr, sizeof(t_host)); + state = st_colon; + } + break; + + /* --- Waiting for a colon coming up --- */ + + case st_colon: + if (ch == EOF) + state = st_commit; + else if (isspace((unsigned char)ch)) + ch = getc(fp); + else if (ch == ':') { + state = st_preport; + ch = getc(fp); + } + else + state = st_commit; + break; + + /* --- Clearing whitespace before a port number --- */ + + case st_preport: + if (ch == EOF) + state = st_commit; + else if (isspace((unsigned char)ch)) + ch = getc(fp); + else { + state = st_port; + p = buff; + } + break; + + /* --- Read a port number --- */ + + case st_port: + if (p == l) + die(1, "string too long in `" file_SERVER "'"); + if (ch != EOF && !isspace((unsigned char)ch) && ch != ':') { + *p++ = ch; + ch = getc(fp); + } else { + struct servent *s; + + *p++ = 0; + s = getservbyname(buff, "udp"); + if (!s && isdigit((unsigned char)buff[0])) + t_port = htons(atoi(buff)); + else if (!s) + die(1, "unknown service `%s' in `" file_SERVER "'", buff); + else + t_port = s->s_port; + state = st_commit; + } + break; + + /* --- A server has been read successfully --- */ + + case st_commit: + if (n_serv == max_serv) { + max_serv *= 2; + serv = xrealloc(serv, n_serv * sizeof(*serv), + max_serv * sizeof(*serv)); + } + serv[n_serv].sin_family = AF_INET; + serv[n_serv].sin_addr = t_host; + serv[n_serv].sin_port = t_port; + n_serv++; + state = st_start; + p = buff; + t_port = port; + break; + + /* --- A safety net for a broken parser --- */ + + default: + die(1, "internal error: can't get here in check__client"); + break; + } + } + } - /* --- Read the reply data --- */ + fclose(fp); - if (recvfrom(fd, (char *)buff, sizeof(buff), 0, - (struct sockaddr *)&sin, &slen) < 0) - die("error reading server's reply: %s", strerror(errno)); + /* --- Now start sending requests --- */ - /* --- Verify the sender --- */ + if (!n_serv) + die(1, "no servers specified in `" file_SERVER "'"); - if (sin.sin_addr.s_addr != ssin.sin_addr.s_addr || - sin.sin_port != ssin.sin_port) - continue; - - /* --- Unpack and verify the response --- */ + IF_TRACING(TRACE_CLIENT, { + size_t i; - answer = crypt_unpackReply(buff, sk, t, pid); - if (answer < 0) - continue; - return (answer); - } + for (i = 0; i < n_serv; i++) { + trace(TRACE_CLIENT, "client: server %s port %i", + inet_ntoa(serv[i].sin_addr), ntohs(serv[i].sin_port)); } - } - - die("internal error: can't get here in check_client"); - return (0); + }) + return (check__ask(rq, serv, n_serv)); } +#endif + +/*----- Main checking function --------------------------------------------*/ + /* --- @check@ --- * * * Arguments: @request *rq@ = pointer to request buffer @@ -240,45 +586,27 @@ int check(request *rq) /* --- Check if we need to talk to a server --- */ - if ((fp = fopen(file_SERVER, "r")) != 0) { - char buff[64]; - int port; - int ch; - - if (fscanf(fp, " %63[^: \t] ", buff) < 1) - die("error in `%s'", file_SERVER); - ch = getc(fp); - if (ch == ':') { - char b[64]; - struct servent *se; - - fscanf(fp, "%s", b); - if ((se = getservbyname(b, 0)) != 0) - port = ntohs(se->s_port); - else if ((port = atoi(b)) == 0) - die("error in `%s'", file_SERVER); - } else { - struct servent *se; - - if ((se = getservbyname(quis(), "udp")) == 0) - die("no idea which port to use"); - port = ntohs(se->s_port); - } - fclose(fp); - return (check__client(rq, buff, port)); - } +#ifndef NONETWORK + if ((fp = fopen(file_SERVER, "r")) != 0) + return (check__client(rq, fp)); +#endif - /* --- Read the configuration in and go --- */ + /* --- Otherwise do this all the old-fashioned way --- */ if ((fp = fopen(file_RULES, "r")) == 0) { - die("couldn't read configuration file `%s': %s", + die(1, "couldn't read configuration file `%s': %s", file_RULES, strerror(errno)); } + userdb_init(); + userdb_local(); + userdb_yp(); + netg_init(); name_init(); rule_init(); lexer_scan(fp); - yyparse(); + parse(); + fclose(fp); return (rule_check(rq)); }