X-Git-Url: https://git.distorted.org.uk/~mdw/become/blobdiff_plain/607937a4e1c4cdb3da09617fa7bfda536278ca95..b0f66028a9a17a845590a4fe737a4f5e46f6b778:/src/check.c diff --git a/src/check.c b/src/check.c index 34d1e52..ed561a7 100644 --- a/src/check.c +++ b/src/check.c @@ -1,10 +1,10 @@ /* -*-c-*- * - * $Id: check.c,v 1.3 1997/08/07 09:49:38 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 */ /*----- Licensing notice --------------------------------------------------* @@ -29,9 +29,44 @@ /*----- Revision history --------------------------------------------------* * * $Log: check.c,v $ - * Revision 1.3 1997/08/07 09:49:38 mdw - * Extensive modifications to handle netgroups. Also sanitise user and group - * names before adding them to the symbol table. + * 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. @@ -62,29 +97,47 @@ #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 "parse.h" #include "userdb.h" -#include "utils.h" -/*----- Main code ---------------------------------------------------------*/ +/*----- Client-end network support ----------------------------------------*/ + +#ifndef NONETWORK /* --- @check__send@ --- * * - * Arguments: @unsigned char *crq@ = pointer to encrypted request + * 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 @@ -96,7 +149,7 @@ * reported. */ -static void check__send(unsigned char *crq, int fd, +static void check__send(char *buf, size_t sz, int fd, struct sockaddr_in *serv, size_t n_serv) { size_t i; @@ -104,7 +157,7 @@ static void check__send(unsigned char *crq, int fd, int err = 0; for (i = 0; i < n_serv; i++) { - if (sendto(fd, (char *)crq, crq_size, 0, + 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)); ) @@ -114,7 +167,7 @@ static void check__send(unsigned char *crq, int fd, } if (!ok) - die("couldn't send request to server: %s", strerror(err)); + die(1, "couldn't send request to server: %s", strerror(err)); } /* --- @check__ask@ --- * @@ -131,173 +184,188 @@ static void check__send(unsigned char *crq, int fd, 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; - unsigned char crq[crq_size]; - unsigned char sk[IDEA_KEYSIZE]; - time_t t; - pid_t pid; - - /* --- First, build the encrypted request packet --- */ - - { - unsigned char k[IDEA_KEYSIZE]; - FILE *fp; + 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; - /* --- Read in the encryption key --- */ + /* --- Open the public keyring --- */ - if ((fp = fopen(file_KEY, "r")) == 0) { - die("couldn't open key file `%s': %s", file_KEY, - strerror(errno)); - } - tx_getBits(k, 128, fp); + 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); - /* --- Now build a request packet --- */ + /* --- Build the request packet --- */ - t = time(0); - pid = getpid(); - crypt_packRequest(rq, crq, t, pid, k, sk); - burn(k); - T( trace(TRACE_CLIENT, "client: encrypted 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 --- */ - { - struct sockaddr_in sin; + if ((fd = socket(PF_INET, SOCK_DGRAM, 0)) < 0) + 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)); - if ((fd = socket(PF_INET, SOCK_DGRAM, 0)) < 0) - die("couldn't create socket: %s", strerror(errno)); + /* --- Bind myself to some address --- */ - /* --- Bind myself to some address --- */ + 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(1, "couldn't bind socket to address: %s", strerror(errno)); - if (bind(fd, (struct sockaddr *)&sin, sizeof(sin)) < 0) - die("couldn't bind socket to address: %s", strerror(errno)); - } + /* --- Find out when we are --- */ - /* --- Now wait for a reply --- */ + gettimeofday(&start, 0); + ind = 0; - { - fd_set fds; - struct timeval start, now, tv; - int ind; - size_t i; + /* --- Now loop until everything's done --- */ + + for (;;) { + gettimeofday(&now, 0); - /* --- State table for waiting for replies --- * + /* --- If the current timer has expired, find one that hasn't --- * * - * For each number, send off the request to our servers, and wait for - * that many seconds to have elapsed since we started. If the number is - * %$-1$% then it's time to give up. + * Also resend the request after I've found a timer which is still + * extant. If there aren't any, report an error. */ - static int tbl[] = { 0, 5, 10, 20, -1 }; + 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"); ) + } - /* --- Find out when we are --- */ + /* --- Now wait for a packet to arrive --- */ - gettimeofday(&start, 0); - ind = 0; + 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; - /* --- Now loop until everything's done --- */ + /* --- Sort out file descriptors to watch --- */ - for (;;) { - gettimeofday(&now, 0); + FD_ZERO(&fds); + FD_SET(fd, &fds); - /* --- 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. - */ + /* --- Wait for them --- */ - if (now.tv_sec >= start.tv_sec + tbl[ind] && - now.tv_usec >= start.tv_usec) { - do { - ind++; - if (tbl[ind] < 0) - die("no reply from servers"); - } while (now.tv_sec >= start.tv_sec + tbl[ind] && - now.tv_usec >= start.tv_usec); - check__send(crq, fd, serv, n_serv); - T( trace(TRACE_CLIENT, "client: send request to servers"); ) - } + 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)); - /* --- Now wait for a packet to arrive --- */ + /* --- Read the reply data --- */ - 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("error waiting for reply: %s", strerror(errno)); - - /* --- A reply should be waiting now --- */ - - { - struct sockaddr_in sin; - int slen = sizeof(sin); - unsigned char buff[256]; - int answer; - - /* --- Read the reply data --- */ - - if (recvfrom(fd, (char *)buff, sizeof(buff), 0, - (struct sockaddr *)&sin, &slen) < 0) - die("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 checksum 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; - } - - /* --- Unpack and verify the response --- */ - - answer = crypt_unpackReply(buff, sk, t, pid); - if (answer < 0) { - T( trace(TRACE_CLIENT, - "client: invalid or corrupt reply packet"); ) - continue; - } - return (answer); + 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; + } + + /* --- 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"); ) } - die("internal error: can't get here in check__ask"); + die(1, "internal error: can't get here in check__ask"); return (0); } @@ -358,7 +426,7 @@ int check__client(request *rq, FILE *fp) { struct servent *s = getservbyname(quis(), "udp"); - port = (s ? s->s_port : -1); + port = (s ? s->s_port : htons(SERVER_PORT)); } /* --- Initialise for scanning the file --- */ @@ -389,7 +457,7 @@ int check__client(request *rq, FILE *fp) case st_host: if (p == l) - die("string too long in `" file_SERVER "'"); + die(1, "string too long in `" file_SERVER "'"); if (ch != EOF && !isspace((unsigned char)ch) && ch != ':') { *p++ = ch; ch = getc(fp); @@ -398,7 +466,7 @@ int check__client(request *rq, FILE *fp) *p++ = 0; if ((h = gethostbyname(buff)) == 0) - die("unknown host `%s' in `" file_SERVER "'", buff); + die(1, "unknown host `%s' in `" file_SERVER "'", buff); memcpy(&t_host, h->h_addr, sizeof(t_host)); state = st_colon; } @@ -436,7 +504,7 @@ int check__client(request *rq, FILE *fp) case st_port: if (p == l) - die("string too long in `" file_SERVER "'"); + die(1, "string too long in `" file_SERVER "'"); if (ch != EOF && !isspace((unsigned char)ch) && ch != ':') { *p++ = ch; ch = getc(fp); @@ -448,7 +516,7 @@ int check__client(request *rq, FILE *fp) if (!s && isdigit((unsigned char)buff[0])) t_port = htons(atoi(buff)); else if (!s) - die("unknown service `%s' in `" file_SERVER "'", buff); + die(1, "unknown service `%s' in `" file_SERVER "'", buff); else t_port = s->s_port; state = st_commit; @@ -460,7 +528,8 @@ int check__client(request *rq, FILE *fp) case st_commit: if (n_serv == max_serv) { max_serv *= 2; - serv = xrealloc(serv, max_serv * sizeof(*serv)); + 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; @@ -474,7 +543,7 @@ int check__client(request *rq, FILE *fp) /* --- A safety net for a broken parser --- */ default: - die("internal error: can't get here in check__client"); + die(1, "internal error: can't get here in check__client"); break; } } @@ -485,7 +554,7 @@ int check__client(request *rq, FILE *fp) /* --- Now start sending requests --- */ if (!n_serv) - die("no servers specified in `" file_SERVER "'"); + die(1, "no servers specified in `" file_SERVER "'"); IF_TRACING(TRACE_CLIENT, { size_t i; @@ -498,6 +567,10 @@ int check__client(request *rq, FILE *fp) return (check__ask(rq, serv, n_serv)); } +#endif + +/*----- Main checking function --------------------------------------------*/ + /* --- @check@ --- * * * Arguments: @request *rq@ = pointer to request buffer @@ -513,13 +586,15 @@ int check(request *rq) /* --- Check if we need to talk to a server --- */ +#ifndef NONETWORK if ((fp = fopen(file_SERVER, "r")) != 0) return (check__client(rq, fp)); +#endif /* --- 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)); } @@ -530,7 +605,8 @@ int check(request *rq) name_init(); rule_init(); lexer_scan(fp); - yyparse(); + parse(); + fclose(fp); return (rule_check(rq)); }