X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/aa3378df3cc7da00b8f93569d0c88f0c626ddb18..94f38e1686aff736c86363eaa705e2ef05463d43:/auth-rsa.c diff --git a/auth-rsa.c b/auth-rsa.c index 2afb1ea3..ee71655f 100644 --- a/auth-rsa.c +++ b/auth-rsa.c @@ -1,53 +1,45 @@ /* - * - * auth-rsa.c - * * Author: Tatu Ylonen - * * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland * All rights reserved - * - * Created: Mon Mar 27 01:46:52 1995 ylo - * * RSA-based authentication. This code determines whether to admit a login * based on RSA authentication. This file also contains functions to check * validity of the host key. - * + * + * As far as I am concerned, the code I have written for this software + * can be used freely for any purpose. Any derived versions of this + * software must be clearly marked as such, and if the derived work is + * incompatible with the protocol description in the RFC file, it must be + * called by a name other than "ssh" or "Secure Shell". */ #include "includes.h" -RCSID("$Id$"); +RCSID("$OpenBSD: auth-rsa.c,v 1.38 2001/01/21 19:05:42 markus Exp $"); + +#include +#include #include "rsa.h" #include "packet.h" #include "xmalloc.h" -#include "ssh.h" +#include "ssh1.h" #include "mpaux.h" #include "uidswap.h" +#include "match.h" +#include "auth-options.h" +#include "pathnames.h" +#include "log.h" #include "servconf.h" +#include "auth.h" -#ifdef HAVE_OPENSSL -#include -#include -#endif -#ifdef HAVE_SSL -#include -#include -#endif - -/* Flags that may be set in authorized_keys options. */ -extern int no_port_forwarding_flag; -extern int no_agent_forwarding_flag; -extern int no_x11_forwarding_flag; -extern int no_pty_flag; -extern char *forced_command; -extern struct envstring *custom_environment; +/* import */ +extern ServerOptions options; /* * Session identifier that is used to bind key exchange and authentication * responses to a particular session. */ -extern unsigned char session_id[16]; +extern u_char session_id[16]; /* * The .ssh/authorized_keys file contains public keys, one per line, in the @@ -66,41 +58,40 @@ extern unsigned char session_id[16]; */ int -auth_rsa_challenge_dialog(BIGNUM *e, BIGNUM *n) +auth_rsa_challenge_dialog(RSA *pk) { - BIGNUM *challenge, *encrypted_challenge, *aux; - RSA *pk; - BN_CTX *ctx = BN_CTX_new(); - unsigned char buf[32], mdbuf[16], response[16]; + BIGNUM *challenge, *encrypted_challenge; + BN_CTX *ctx; + u_char buf[32], mdbuf[16], response[16]; MD5_CTX md; - unsigned int i; + u_int i; int plen, len; encrypted_challenge = BN_new(); challenge = BN_new(); - aux = BN_new(); /* Generate a random challenge. */ BN_rand(challenge, 256, 0, 0); - BN_mod(challenge, challenge, n, ctx); - - /* Create the public key data structure. */ - pk = RSA_new(); - pk->e = BN_new(); - BN_copy(pk->e, e); - pk->n = BN_new(); - BN_copy(pk->n, n); + ctx = BN_CTX_new(); + BN_mod(challenge, challenge, pk->n, ctx); + BN_CTX_free(ctx); /* Encrypt the challenge with the public key. */ rsa_public_encrypt(encrypted_challenge, challenge, pk); - RSA_free(pk); /* Send the encrypted challenge to the client. */ packet_start(SSH_SMSG_AUTH_RSA_CHALLENGE); packet_put_bignum(encrypted_challenge); packet_send(); + BN_clear_free(encrypted_challenge); packet_write_wait(); + /* Wait for a response. */ + packet_read_expect(&plen, SSH_CMSG_AUTH_RSA_RESPONSE); + packet_integrity_check(plen, 16, SSH_CMSG_AUTH_RSA_RESPONSE); + for (i = 0; i < 16; i++) + response[i] = packet_get_char(); + /* The response is MD5 of decrypted challenge plus session id. */ len = BN_num_bytes(challenge); if (len <= 0 || len > 32) @@ -111,18 +102,7 @@ auth_rsa_challenge_dialog(BIGNUM *e, BIGNUM *n) MD5_Update(&md, buf, 32); MD5_Update(&md, session_id, 16); MD5_Final(mdbuf, &md); - - /* We will no longer need these. */ - BN_clear_free(encrypted_challenge); BN_clear_free(challenge); - BN_clear_free(aux); - BN_CTX_free(ctx); - - /* Wait for a response. */ - packet_read_expect(&plen, SSH_CMSG_AUTH_RSA_RESPONSE); - packet_integrity_check(plen, 16, SSH_CMSG_AUTH_RSA_RESPONSE); - for (i = 0; i < 16; i++) - response[i] = packet_get_char(); /* Verify that the response is the original challenge. */ if (memcmp(response, mdbuf, 16) != 0) { @@ -142,21 +122,24 @@ auth_rsa_challenge_dialog(BIGNUM *e, BIGNUM *n) int auth_rsa(struct passwd *pw, BIGNUM *client_n) { - extern ServerOptions options; - char line[8192], file[1024]; + char line[8192], file[MAXPATHLEN]; int authenticated; - unsigned int bits; + u_int bits; FILE *f; - unsigned long linenum = 0; + u_long linenum = 0; struct stat st; - BIGNUM *e, *n; + RSA *pk; + + /* no user given */ + if (pw == NULL) + return 0; /* Temporarily use the user's uid. */ temporarily_use_uid(pw->pw_uid); /* The authorized keys. */ snprintf(file, sizeof file, "%.500s/%.100s", pw->pw_dir, - SSH_USER_PERMITTED_KEYS); + _PATH_SSH_USER_PERMITTED_KEYS); /* Fail quietly if file does not exist */ if (stat(file, &st) < 0) { @@ -184,10 +167,10 @@ auth_rsa(struct passwd *pw, BIGNUM *client_n) "bad ownership or modes for '%s'.", pw->pw_name, file); fail = 1; } else { - /* Check path to SSH_USER_PERMITTED_KEYS */ + /* Check path to _PATH_SSH_USER_PERMITTED_KEYS */ int i; static const char *check[] = { - "", SSH_USER_DIR, NULL + "", _PATH_SSH_USER_DIR, NULL }; for (i = 0; check[i]; i++) { snprintf(line, sizeof line, "%.500s/%.100s", pw->pw_dir, check[i]); @@ -202,8 +185,9 @@ auth_rsa(struct passwd *pw, BIGNUM *client_n) } } if (fail) { - log(buf); - packet_send_debug(buf); + fclose(f); + log("%s",buf); + packet_send_debug("%s",buf); restore_uid(); return 0; } @@ -211,8 +195,9 @@ auth_rsa(struct passwd *pw, BIGNUM *client_n) /* Flag indicating whether authentication has succeeded. */ authenticated = 0; - e = BN_new(); - n = BN_new(); + pk = RSA_new(); + pk->e = BN_new(); + pk->n = BN_new(); /* * Go though the accepted keys, looking for the current key. If @@ -250,29 +235,35 @@ auth_rsa(struct passwd *pw, BIGNUM *client_n) options = NULL; /* Parse the key from the line. */ - if (!auth_rsa_read_key(&cp, &bits, e, n)) { + if (!auth_rsa_read_key(&cp, &bits, pk->e, pk->n)) { debug("%.100s, line %lu: bad key syntax", - SSH_USER_PERMITTED_KEYS, linenum); + file, linenum); packet_send_debug("%.100s, line %lu: bad key syntax", - SSH_USER_PERMITTED_KEYS, linenum); + file, linenum); continue; } /* cp now points to the comment part. */ - /* check the real bits */ - if (bits != BN_num_bits(n)) - error("Warning: error in %s, line %ld: keysize mismatch: " - "actual size %d vs. announced %d.", - file, linenum, BN_num_bits(n), bits); - /* Check if the we have found the desired key (identified by its modulus). */ - if (BN_cmp(n, client_n) != 0) + if (BN_cmp(pk->n, client_n) != 0) continue; + /* check the real bits */ + if (bits != BN_num_bits(pk->n)) + log("Warning: %s, line %ld: keysize mismatch: " + "actual %d vs. announced %d.", + file, linenum, BN_num_bits(pk->n), bits); + /* We have found the desired key. */ + /* + * If our options do not allow this key to be used, + * do not send challenge. + */ + if (!auth_parse_options(pw, options, file, linenum)) + continue; /* Perform the challenge-response dialog for this key. */ - if (!auth_rsa_challenge_dialog(e, n)) { + if (!auth_rsa_challenge_dialog(pk)) { /* Wrong response. */ verbose("Wrong response to RSA authentication challenge."); packet_send_debug("Wrong response to RSA authentication challenge."); @@ -283,175 +274,11 @@ auth_rsa(struct passwd *pw, BIGNUM *client_n) * authenticated. Note that we have not yet processed the * options; this will be reset if the options cause the * authentication to be rejected. - */ - authenticated = 1; - - /* RSA part of authentication was accepted. Now process the options. */ - if (options) { - while (*options && *options != ' ' && *options != '\t') { - cp = "no-port-forwarding"; - if (strncmp(options, cp, strlen(cp)) == 0) { - packet_send_debug("Port forwarding disabled."); - no_port_forwarding_flag = 1; - options += strlen(cp); - goto next_option; - } - cp = "no-agent-forwarding"; - if (strncmp(options, cp, strlen(cp)) == 0) { - packet_send_debug("Agent forwarding disabled."); - no_agent_forwarding_flag = 1; - options += strlen(cp); - goto next_option; - } - cp = "no-X11-forwarding"; - if (strncmp(options, cp, strlen(cp)) == 0) { - packet_send_debug("X11 forwarding disabled."); - no_x11_forwarding_flag = 1; - options += strlen(cp); - goto next_option; - } - cp = "no-pty"; - if (strncmp(options, cp, strlen(cp)) == 0) { - packet_send_debug("Pty allocation disabled."); - no_pty_flag = 1; - options += strlen(cp); - goto next_option; - } - cp = "command=\""; - if (strncmp(options, cp, strlen(cp)) == 0) { - int i; - options += strlen(cp); - forced_command = xmalloc(strlen(options) + 1); - i = 0; - while (*options) { - if (*options == '"') - break; - if (*options == '\\' && options[1] == '"') { - options += 2; - forced_command[i++] = '"'; - continue; - } - forced_command[i++] = *options++; - } - if (!*options) { - debug("%.100s, line %lu: missing end quote", - SSH_USER_PERMITTED_KEYS, linenum); - packet_send_debug("%.100s, line %lu: missing end quote", - SSH_USER_PERMITTED_KEYS, linenum); - continue; - } - forced_command[i] = 0; - packet_send_debug("Forced command: %.900s", forced_command); - options++; - goto next_option; - } - cp = "environment=\""; - if (strncmp(options, cp, strlen(cp)) == 0) { - int i; - char *s; - struct envstring *new_envstring; - options += strlen(cp); - s = xmalloc(strlen(options) + 1); - i = 0; - while (*options) { - if (*options == '"') - break; - if (*options == '\\' && options[1] == '"') { - options += 2; - s[i++] = '"'; - continue; - } - s[i++] = *options++; - } - if (!*options) { - debug("%.100s, line %lu: missing end quote", - SSH_USER_PERMITTED_KEYS, linenum); - packet_send_debug("%.100s, line %lu: missing end quote", - SSH_USER_PERMITTED_KEYS, linenum); - continue; - } - s[i] = 0; - packet_send_debug("Adding to environment: %.900s", s); - debug("Adding to environment: %.900s", s); - options++; - new_envstring = xmalloc(sizeof(struct envstring)); - new_envstring->s = s; - new_envstring->next = custom_environment; - custom_environment = new_envstring; - goto next_option; - } - cp = "from=\""; - if (strncmp(options, cp, strlen(cp)) == 0) { - char *patterns = xmalloc(strlen(options) + 1); - int i; - options += strlen(cp); - i = 0; - while (*options) { - if (*options == '"') - break; - if (*options == '\\' && options[1] == '"') { - options += 2; - patterns[i++] = '"'; - continue; - } - patterns[i++] = *options++; - } - if (!*options) { - debug("%.100s, line %lu: missing end quote", - SSH_USER_PERMITTED_KEYS, linenum); - packet_send_debug("%.100s, line %lu: missing end quote", - SSH_USER_PERMITTED_KEYS, linenum); - continue; - } - patterns[i] = 0; - options++; - if (!match_hostname(get_canonical_hostname(), patterns, - strlen(patterns)) && - !match_hostname(get_remote_ipaddr(), patterns, - strlen(patterns))) { - log("RSA authentication tried for %.100s with correct key but not from a permitted host (host=%.200s, ip=%.200s).", - pw->pw_name, get_canonical_hostname(), - get_remote_ipaddr()); - packet_send_debug("Your host '%.200s' is not permitted to use this key for login.", - get_canonical_hostname()); - xfree(patterns); - authenticated = 0; - break; - } - xfree(patterns); - /* Host name matches. */ - goto next_option; - } - bad_option: - log("Bad options in %.100s file, line %lu: %.50s", - SSH_USER_PERMITTED_KEYS, linenum, options); - packet_send_debug("Bad options in %.100s file, line %lu: %.50s", - SSH_USER_PERMITTED_KEYS, linenum, options); - authenticated = 0; - break; - - next_option: - /* - * Skip the comma, and move to the next option - * (or break out if there are no more). - */ - if (!*options) - fatal("Bugs in auth-rsa.c option processing."); - if (*options == ' ' || *options == '\t') - break; /* End of options. */ - if (*options != ',') - goto bad_option; - options++; - /* Process the next option. */ - continue; - } - } - /* * Break out of the loop if authentication was successful; * otherwise continue searching. */ - if (authenticated) - break; + authenticated = 1; + break; } /* Restore the privileged uid. */ @@ -460,11 +287,12 @@ auth_rsa(struct passwd *pw, BIGNUM *client_n) /* Close the file. */ fclose(f); - BN_clear_free(n); - BN_clear_free(e); + RSA_free(pk); if (authenticated) packet_send_debug("RSA authentication accepted."); + else + auth_clear_options(); /* Return authentication result. */ return authenticated;