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-rw-r--r--crypto/openssh/auth-rsa.c349
1 files changed, 0 insertions, 349 deletions
diff --git a/crypto/openssh/auth-rsa.c b/crypto/openssh/auth-rsa.c
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index cbd971b..0000000
--- a/crypto/openssh/auth-rsa.c
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-/* $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 */
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