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Diff for /src/usr.bin/ssh/Attic/auth-rsa.c between version 1.40.2.3 and 1.41

version 1.40.2.3, 2002/06/02 22:56:09 version 1.41, 2001/05/20 17:20:35
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 #include "log.h"  #include "log.h"
 #include "servconf.h"  #include "servconf.h"
 #include "auth.h"  #include "auth.h"
 #include "hostfile.h"  
 #include "monitor_wrap.h"  
 #include "ssh.h"  
   
 /* import */  /* import */
 extern ServerOptions options;  extern ServerOptions options;
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  * description of the options.   * 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. */  
         BN_rand(challenge, 256, 0, 0);  
         if ((ctx = BN_CTX_new()) == NULL)  
                 fatal("auth_rsa_generate_challenge: BN_CTX_new() failed");  
         BN_mod(challenge, challenge, key->rsa->n, ctx);  
         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];  
         MD5_CTX md;  
         int len;  
   
         /* don't allow short keys */  
         if (BN_num_bits(key->rsa->n) < SSH_RSA_MINIMUM_MODULUS_SIZE) {  
                 error("auth_rsa_verify_response: n too small: %d bits",  
                     BN_num_bits(key->rsa->n));  
                 return (0);  
         }  
   
         /* The response is MD5 of decrypted challenge plus session id. */  
         len = BN_num_bytes(challenge);  
         if (len <= 0 || len > 32)  
                 fatal("auth_rsa_verify_response: bad challenge length %d", len);  
         memset(buf, 0, 32);  
         BN_bn2bin(challenge, buf + 32 - len);  
         MD5_Init(&md);  
         MD5_Update(&md, buf, 32);  
         MD5_Update(&md, session_id, 16);  
         MD5_Final(mdbuf, &md);  
   
         /* Verify that the response is the original challenge. */  
         if (memcmp(response, mdbuf, 16) != 0) {  
                 /* Wrong answer. */  
                 return (0);  
         }  
         /* Correct answer. */  
         return (1);  
 }  
   
 /*  /*
  * Performs the RSA authentication challenge-response dialog with the client,   * Performs the RSA authentication challenge-response dialog with the client,
  * and returns true (non-zero) if the client gave the correct answer to   * and returns true (non-zero) if the client gave the correct answer to
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  */   */
   
 int  int
 auth_rsa_challenge_dialog(Key *key)  auth_rsa_challenge_dialog(RSA *pk)
 {  {
         BIGNUM *challenge, *encrypted_challenge;          BIGNUM *challenge, *encrypted_challenge;
         u_char response[16];          BN_CTX *ctx;
         int i, success;          u_char buf[32], mdbuf[16], response[16];
           MD5_CTX md;
           u_int i;
           int plen, len;
   
         if ((encrypted_challenge = BN_new()) == NULL)          encrypted_challenge = BN_new();
                 fatal("auth_rsa_challenge_dialog: BN_new() failed");          challenge = BN_new();
   
         challenge = PRIVSEP(auth_rsa_generate_challenge(key));          /* Generate a random challenge. */
           BN_rand(challenge, 256, 0, 0);
           ctx = BN_CTX_new();
           BN_mod(challenge, challenge, pk->n, ctx);
           BN_CTX_free(ctx);
   
         /* Encrypt the challenge with the public key. */          /* Encrypt the challenge with the public key. */
         rsa_public_encrypt(encrypted_challenge, challenge, key->rsa);          rsa_public_encrypt(encrypted_challenge, challenge, pk);
   
         /* Send the encrypted challenge to the client. */          /* Send the encrypted challenge to the client. */
         packet_start(SSH_SMSG_AUTH_RSA_CHALLENGE);          packet_start(SSH_SMSG_AUTH_RSA_CHALLENGE);
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         packet_write_wait();          packet_write_wait();
   
         /* Wait for a response. */          /* Wait for a response. */
         packet_read_expect(SSH_CMSG_AUTH_RSA_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++)          for (i = 0; i < 16; i++)
                 response[i] = packet_get_char();                  response[i] = packet_get_char();
         packet_check_eom();  
   
         success = PRIVSEP(auth_rsa_verify_response(key, challenge, response));          /* The response is MD5 of decrypted challenge plus session id. */
           len = BN_num_bytes(challenge);
           if (len <= 0 || len > 32)
                   fatal("auth_rsa_challenge_dialog: bad challenge length %d", len);
           memset(buf, 0, 32);
           BN_bn2bin(challenge, buf + 32 - len);
           MD5_Init(&md);
           MD5_Update(&md, buf, 32);
           MD5_Update(&md, session_id, 16);
           MD5_Final(mdbuf, &md);
         BN_clear_free(challenge);          BN_clear_free(challenge);
         return (success);  
           /* Verify that the response is the original challenge. */
           if (memcmp(response, mdbuf, 16) != 0) {
                   /* Wrong answer. */
                   return 0;
           }
           /* Correct answer. */
           return 1;
 }  }
   
 /*  /*
  * check if there's user key matching client_n,   * Performs the RSA authentication dialog with the client.  This returns
  * return key if login is allowed, NULL otherwise   * 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  int
 auth_rsa_key_allowed(struct passwd *pw, BIGNUM *client_n, Key **rkey)  auth_rsa(struct passwd *pw, BIGNUM *client_n)
 {  {
         char line[8192], *file;          char line[8192], *file;
         int allowed = 0;          int authenticated;
         u_int bits;          u_int bits;
         FILE *f;          FILE *f;
         u_long linenum = 0;          u_long linenum = 0;
         struct stat st;          struct stat st;
         Key *key;          RSA *pk;
   
           /* no user given */
           if (pw == NULL)
                   return 0;
   
         /* Temporarily use the user's uid. */          /* Temporarily use the user's uid. */
         temporarily_use_uid(pw);          temporarily_use_uid(pw);
   
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                 /* Restore the privileged uid. */                  /* Restore the privileged uid. */
                 restore_uid();                  restore_uid();
                 xfree(file);                  xfree(file);
                 return (0);                  return 0;
         }          }
         /* Open the file containing the authorized keys. */          /* Open the file containing the authorized keys. */
         f = fopen(file, "r");          f = fopen(file, "r");
         if (!f) {          if (!f) {
                 /* Restore the privileged uid. */                  /* Restore the privileged uid. */
                 restore_uid();                  restore_uid();
                   packet_send_debug("Could not open %.900s for reading.", file);
                   packet_send_debug("If your home is on an NFS volume, it may need to be world-readable.");
                 xfree(file);                  xfree(file);
                 return (0);                  return 0;
         }          }
         if (options.strict_modes &&          if (options.strict_modes &&
             secure_filename(f, file, pw, line, sizeof(line)) != 0) {              secure_filename(f, file, pw->pw_uid, line, sizeof(line)) != 0) {
                 xfree(file);                  xfree(file);
                 fclose(f);                  fclose(f);
                 log("Authentication refused: %s", line);                  log("Authentication refused: %s", line);
                   packet_send_debug("Authentication refused: %s", line);
                 restore_uid();                  restore_uid();
                 return (0);                  return 0;
         }          }
           /* Flag indicating whether authentication has succeeded. */
           authenticated = 0;
   
         /* Flag indicating whether the key is allowed. */          pk = RSA_new();
         allowed = 0;          pk->e = BN_new();
           pk->n = BN_new();
   
         key = key_new(KEY_RSA1);  
   
         /*          /*
          * Go though the accepted keys, looking for the current key.  If           * Go though the accepted keys, looking for the current key.  If
          * found, perform a challenge-response dialog to verify that the           * found, perform a challenge-response dialog to verify that the
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                         options = NULL;                          options = NULL;
   
                 /* Parse the key from the line. */                  /* Parse the key from the line. */
                 if (hostfile_read_key(&cp, &bits, key) == 0) {                  if (!auth_rsa_read_key(&cp, &bits, pk->e, pk->n)) {
                         debug("%.100s, line %lu: non ssh1 key syntax",                          debug("%.100s, line %lu: bad key syntax",
                             file, linenum);                              file, linenum);
                           packet_send_debug("%.100s, line %lu: bad key syntax",
                               file, linenum);
                         continue;                          continue;
                 }                  }
                 /* cp now points to the comment part. */                  /* cp now points to the comment part. */
   
                 /* Check if the we have found the desired key (identified by its modulus). */                  /* Check if the we have found the desired key (identified by its modulus). */
                 if (BN_cmp(key->rsa->n, client_n) != 0)                  if (BN_cmp(pk->n, client_n) != 0)
                         continue;                          continue;
   
                 /* check the real bits  */                  /* check the real bits  */
                 if (bits != BN_num_bits(key->rsa->n))                  if (bits != BN_num_bits(pk->n))
                         log("Warning: %s, line %lu: keysize mismatch: "                          log("Warning: %s, line %ld: keysize mismatch: "
                             "actual %d vs. announced %d.",                              "actual %d vs. announced %d.",
                             file, linenum, BN_num_bits(key->rsa->n), bits);                              file, linenum, BN_num_bits(pk->n), bits);
   
                 /* We have found the desired key. */                  /* We have found the desired key. */
                 /*                  /*
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                 if (!auth_parse_options(pw, options, file, linenum))                  if (!auth_parse_options(pw, options, file, linenum))
                         continue;                          continue;
   
                 /* break out, this key is allowed */                  /* Perform the challenge-response dialog for this key. */
                 allowed = 1;                  if (!auth_rsa_challenge_dialog(pk)) {
                           /* Wrong response. */
                           verbose("Wrong response to RSA authentication challenge.");
                           packet_send_debug("Wrong response to RSA authentication challenge.");
                           continue;
                   }
                   /*
                    * 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.
                    * Break out of the loop if authentication was successful;
                    * otherwise continue searching.
                    */
                   authenticated = 1;
                 break;                  break;
         }          }
   
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         xfree(file);          xfree(file);
         fclose(f);          fclose(f);
   
         /* return key if allowed */          RSA_free(pk);
         if (allowed && rkey != NULL)  
                 *rkey = key;  
         else  
                 key_free(key);  
         return (allowed);  
 }  
   
 /*          if (authenticated)
  * Performs the RSA authentication dialog with the client.  This returns                  packet_send_debug("RSA authentication accepted.");
  * 0 if the client could not be authenticated, and 1 if authentication was          else
  * successful.  This may exit if there is a serious protocol violation.  
  */  
 int  
 auth_rsa(struct passwd *pw, BIGNUM *client_n)  
 {  
         Key *key;  
         char *fp;  
   
         /* no user given */  
         if (pw == NULL)  
                 return 0;  
   
         if (!PRIVSEP(auth_rsa_key_allowed(pw, client_n, &key))) {  
                 auth_clear_options();                  auth_clear_options();
                 return (0);  
         }  
   
         /* Perform the challenge-response dialog for this key. */          /* Return authentication result. */
         if (!auth_rsa_challenge_dialog(key)) {          return authenticated;
                 /* 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.  
          */  
         fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);  
         verbose("Found matching %s key: %s",  
             key_type(key), fp);  
         xfree(fp);  
         key_free(key);  
   
         packet_send_debug("RSA authentication accepted.");  
         return (1);  
 }  }
Legend:
Removed from v.1.40.2.3  
changed lines
  Added in v.1.41