diff options
Diffstat (limited to 'auth-rsa.c')
| -rw-r--r-- | auth-rsa.c | 349 |
1 files changed, 0 insertions, 349 deletions
diff --git a/auth-rsa.c b/auth-rsa.c deleted file mode 100644 index cbd971be1f178..0000000000000 --- a/auth-rsa.c +++ /dev/null @@ -1,349 +0,0 @@ -/* $OpenBSD: auth-rsa.c,v 1.90 2015/01/28 22:36:00 djm Exp $ */ -/* - * Author: Tatu Ylonen <ylo@cs.hut.fi> - * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland - * All rights reserved - * 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" - -#ifdef WITH_SSH1 - -#include <sys/types.h> -#include <sys/stat.h> - -#include <openssl/rsa.h> - -#include <pwd.h> -#include <stdio.h> -#include <stdarg.h> -#include <string.h> - -#include "xmalloc.h" -#include "rsa.h" -#include "packet.h" -#include "ssh1.h" -#include "uidswap.h" -#include "match.h" -#include "buffer.h" -#include "pathnames.h" -#include "log.h" -#include "misc.h" -#include "servconf.h" -#include "key.h" -#include "auth-options.h" -#include "hostfile.h" -#include "auth.h" -#ifdef GSSAPI -#include "ssh-gss.h" -#endif -#include "monitor_wrap.h" -#include "ssh.h" - -#include "digest.h" - -/* import */ -extern ServerOptions options; - -/* - * Session identifier that is used to bind key exchange and authentication - * responses to a particular session. - */ -extern u_char session_id[16]; - -/* - * The .ssh/authorized_keys file contains public keys, one per line, in the - * following format: - * options bits e n comment - * where bits, e and n are decimal numbers, - * and comment is any string of characters up to newline. The maximum - * length of a line is SSH_MAX_PUBKEY_BYTES characters. See sshd(8) for a - * description of the options. - */ - -BIGNUM * -auth_rsa_generate_challenge(Key *key) -{ - BIGNUM *challenge; - BN_CTX *ctx; - - if ((challenge = BN_new()) == NULL) - fatal("auth_rsa_generate_challenge: BN_new() failed"); - /* Generate a random challenge. */ - if (BN_rand(challenge, 256, 0, 0) == 0) - fatal("auth_rsa_generate_challenge: BN_rand failed"); - if ((ctx = BN_CTX_new()) == NULL) - fatal("auth_rsa_generate_challenge: BN_CTX_new failed"); - if (BN_mod(challenge, challenge, key->rsa->n, ctx) == 0) - fatal("auth_rsa_generate_challenge: BN_mod failed"); - BN_CTX_free(ctx); - - return challenge; -} - -int -auth_rsa_verify_response(Key *key, BIGNUM *challenge, u_char response[16]) -{ - u_char buf[32], mdbuf[16]; - struct ssh_digest_ctx *md; - int len; - - /* don't allow short keys */ - if (BN_num_bits(key->rsa->n) < SSH_RSA_MINIMUM_MODULUS_SIZE) { - error("%s: RSA modulus too small: %d < minimum %d bits", - __func__, - BN_num_bits(key->rsa->n), SSH_RSA_MINIMUM_MODULUS_SIZE); - return (0); - } - - /* The response is MD5 of decrypted challenge plus session id. */ - len = BN_num_bytes(challenge); - if (len <= 0 || len > 32) - fatal("%s: bad challenge length %d", __func__, len); - memset(buf, 0, 32); - BN_bn2bin(challenge, buf + 32 - len); - if ((md = ssh_digest_start(SSH_DIGEST_MD5)) == NULL || - ssh_digest_update(md, buf, 32) < 0 || - ssh_digest_update(md, session_id, 16) < 0 || - ssh_digest_final(md, mdbuf, sizeof(mdbuf)) < 0) - fatal("%s: md5 failed", __func__); - ssh_digest_free(md); - - /* Verify that the response is the original challenge. */ - if (timingsafe_bcmp(response, mdbuf, 16) != 0) { - /* Wrong answer. */ - return (0); - } - /* Correct answer. */ - return (1); -} - -/* - * Performs the RSA authentication challenge-response dialog with the client, - * and returns true (non-zero) if the client gave the correct answer to - * our challenge; returns zero if the client gives a wrong answer. - */ - -int -auth_rsa_challenge_dialog(Key *key) -{ - BIGNUM *challenge, *encrypted_challenge; - u_char response[16]; - int i, success; - - if ((encrypted_challenge = BN_new()) == NULL) - fatal("auth_rsa_challenge_dialog: BN_new() failed"); - - challenge = PRIVSEP(auth_rsa_generate_challenge(key)); - - /* Encrypt the challenge with the public key. */ - if (rsa_public_encrypt(encrypted_challenge, challenge, key->rsa) != 0) - fatal("%s: rsa_public_encrypt failed", __func__); - - /* 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(SSH_CMSG_AUTH_RSA_RESPONSE); - for (i = 0; i < 16; i++) - response[i] = (u_char)packet_get_char(); - packet_check_eom(); - - success = PRIVSEP(auth_rsa_verify_response(key, challenge, response)); - BN_clear_free(challenge); - return (success); -} - -static int -rsa_key_allowed_in_file(struct passwd *pw, char *file, - const BIGNUM *client_n, Key **rkey) -{ - char *fp, line[SSH_MAX_PUBKEY_BYTES]; - int allowed = 0, bits; - FILE *f; - u_long linenum = 0; - Key *key; - - debug("trying public RSA key file %s", file); - if ((f = auth_openkeyfile(file, pw, options.strict_modes)) == NULL) - return 0; - - /* - * Go though the accepted keys, looking for the current key. If - * found, perform a challenge-response dialog to verify that the - * user really has the corresponding private key. - */ - key = key_new(KEY_RSA1); - while (read_keyfile_line(f, file, line, sizeof(line), &linenum) != -1) { - char *cp; - char *key_options; - int keybits; - - /* Skip leading whitespace, empty and comment lines. */ - for (cp = line; *cp == ' ' || *cp == '\t'; cp++) - ; - if (!*cp || *cp == '\n' || *cp == '#') - continue; - - /* - * Check if there are options for this key, and if so, - * save their starting address and skip the option part - * for now. If there are no options, set the starting - * address to NULL. - */ - if (*cp < '0' || *cp > '9') { - int quoted = 0; - key_options = cp; - for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) { - if (*cp == '\\' && cp[1] == '"') - cp++; /* Skip both */ - else if (*cp == '"') - quoted = !quoted; - } - } else - key_options = NULL; - - /* Parse the key from the line. */ - if (hostfile_read_key(&cp, &bits, key) == 0) { - debug("%.100s, line %lu: non ssh1 key syntax", - file, linenum); - continue; - } - /* cp now points to the comment part. */ - - /* - * Check if the we have found the desired key (identified - * by its modulus). - */ - if (BN_cmp(key->rsa->n, client_n) != 0) - continue; - - /* check the real bits */ - keybits = BN_num_bits(key->rsa->n); - if (keybits < 0 || bits != keybits) - logit("Warning: %s, line %lu: keysize mismatch: " - "actual %d vs. announced %d.", - file, linenum, BN_num_bits(key->rsa->n), bits); - - if ((fp = sshkey_fingerprint(key, options.fingerprint_hash, - SSH_FP_DEFAULT)) == NULL) - continue; - debug("matching key found: file %s, line %lu %s %s", - file, linenum, key_type(key), fp); - free(fp); - - /* Never accept a revoked key */ - if (auth_key_is_revoked(key)) - break; - - /* 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, key_options, file, linenum)) - continue; - if (key_is_cert_authority) - continue; - /* break out, this key is allowed */ - allowed = 1; - break; - } - - /* Close the file. */ - fclose(f); - - /* return key if allowed */ - if (allowed && rkey != NULL) - *rkey = key; - else - key_free(key); - - return allowed; -} - -/* - * check if there's user key matching client_n, - * return key if login is allowed, NULL otherwise - */ - -int -auth_rsa_key_allowed(struct passwd *pw, BIGNUM *client_n, Key **rkey) -{ - char *file; - u_int i, allowed = 0; - - temporarily_use_uid(pw); - - for (i = 0; !allowed && i < options.num_authkeys_files; i++) { - if (strcasecmp(options.authorized_keys_files[i], "none") == 0) - continue; - file = expand_authorized_keys( - options.authorized_keys_files[i], pw); - allowed = rsa_key_allowed_in_file(pw, file, client_n, rkey); - free(file); - } - - restore_uid(); - - return allowed; -} - -/* - * Performs the RSA authentication dialog with the client. This returns - * 0 if the client could not be authenticated, and 1 if authentication was - * successful. This may exit if there is a serious protocol violation. - */ -int -auth_rsa(Authctxt *authctxt, BIGNUM *client_n) -{ - Key *key; - struct passwd *pw = authctxt->pw; - - /* no user given */ - if (!authctxt->valid) - return 0; - - if (!PRIVSEP(auth_rsa_key_allowed(pw, client_n, &key))) { - auth_clear_options(); - return (0); - } - - /* Perform the challenge-response dialog for this key. */ - if (!auth_rsa_challenge_dialog(key)) { - /* Wrong response. */ - verbose("Wrong response to RSA authentication challenge."); - packet_send_debug("Wrong response to RSA authentication challenge."); - /* - * Break out of the loop. Otherwise we might send - * another challenge and break the protocol. - */ - key_free(key); - return (0); - } - /* - * Correct response. The client has been successfully - * authenticated. Note that we have not yet processed the - * options; this will be reset if the options cause the - * authentication to be rejected. - */ - pubkey_auth_info(authctxt, key, NULL); - - packet_send_debug("RSA authentication accepted."); - return (1); -} - -#endif /* WITH_SSH1 */ |