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Diff for /src/usr.bin/ssh/auth.c between version 1.11 and 1.11.2.6

version 1.11, 2000/10/11 20:27:23 version 1.11.2.6, 2001/11/15 00:14:59
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 /*  /*
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland   * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  *                    All rights reserved  
  *   *
  * 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".  
  *  
  *  
  * Copyright (c) 2000 Markus Friedl. All rights reserved.  
  *  
  * Redistribution and use in source and binary forms, with or without   * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions   * modification, are permitted provided that the following conditions
  * are met:   * are met:
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 #include "includes.h"  #include "includes.h"
 RCSID("$OpenBSD$");  RCSID("$OpenBSD$");
   
   #include <libgen.h>
   
 #include "xmalloc.h"  #include "xmalloc.h"
 #include "rsa.h"  
 #include "ssh.h"  
 #include "pty.h"  
 #include "packet.h"  
 #include "buffer.h"  
 #include "mpaux.h"  
 #include "servconf.h"  
 #include "compat.h"  
 #include "channels.h"  
 #include "match.h"  #include "match.h"
   #include "groupaccess.h"
 #include "bufaux.h"  #include "log.h"
 #include "ssh2.h"  #include "servconf.h"
 #include "auth.h"  #include "auth.h"
 #include "session.h"  #include "auth-options.h"
   #include "canohost.h"
   #include "buffer.h"
   #include "bufaux.h"
   #include "uidswap.h"
   #include "tildexpand.h"
   
 /* import */  /* import */
 extern ServerOptions options;  extern ServerOptions options;
   
 /*  /*
  * Check if the user is allowed to log in via ssh. If user is listed in   * Check if the user is allowed to log in via ssh. If user is listed
  * DenyUsers or user's primary group is listed in DenyGroups, false will   * in DenyUsers or one of user's groups is listed in DenyGroups, false
  * be returned. If AllowUsers isn't empty and user isn't listed there, or   * will be returned. If AllowUsers isn't empty and user isn't listed
  * if AllowGroups isn't empty and user isn't listed there, false will be   * there, or if AllowGroups isn't empty and one of user's groups isn't
  * returned.   * listed there, false will be returned.
  * If the user's shell is not executable, false will be returned.   * If the user's shell is not executable, false will be returned.
  * Otherwise true is returned.   * Otherwise true is returned.
  */   */
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 allowed_user(struct passwd * pw)  allowed_user(struct passwd * pw)
 {  {
         struct stat st;          struct stat st;
         struct group *grp;          const char *hostname = NULL, *ipaddr = NULL;
         char *shell;          char *shell;
         int i;          int i;
   
         /* Shouldn't be called if pw is NULL, but better safe than sorry... */          /* Shouldn't be called if pw is NULL, but better safe than sorry... */
         if (!pw)          if (!pw || !pw->pw_name)
                 return 0;                  return 0;
   
         /*          /*
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         if (!((st.st_mode & S_IFREG) && (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP))))          if (!((st.st_mode & S_IFREG) && (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP))))
                 return 0;                  return 0;
   
           if (options.num_deny_users > 0 || options.num_allow_users > 0) {
                   hostname = get_canonical_hostname(options.reverse_mapping_check);
                   ipaddr = get_remote_ipaddr();
           }
   
         /* Return false if user is listed in DenyUsers */          /* Return false if user is listed in DenyUsers */
         if (options.num_deny_users > 0) {          if (options.num_deny_users > 0) {
                 if (!pw->pw_name)  
                         return 0;  
                 for (i = 0; i < options.num_deny_users; i++)                  for (i = 0; i < options.num_deny_users; i++)
                         if (match_pattern(pw->pw_name, options.deny_users[i]))                          if (match_user(pw->pw_name, hostname, ipaddr,
                               options.deny_users[i]))
                                 return 0;                                  return 0;
         }          }
         /* Return false if AllowUsers isn't empty and user isn't listed there */          /* Return false if AllowUsers isn't empty and user isn't listed there */
         if (options.num_allow_users > 0) {          if (options.num_allow_users > 0) {
                 if (!pw->pw_name)  
                         return 0;  
                 for (i = 0; i < options.num_allow_users; i++)                  for (i = 0; i < options.num_allow_users; i++)
                         if (match_pattern(pw->pw_name, options.allow_users[i]))                          if (match_user(pw->pw_name, hostname, ipaddr,
                               options.allow_users[i]))
                                 break;                                  break;
                 /* i < options.num_allow_users iff we break for loop */                  /* i < options.num_allow_users iff we break for loop */
                 if (i >= options.num_allow_users)                  if (i >= options.num_allow_users)
                         return 0;                          return 0;
         }          }
         /* Get the primary group name if we need it. Return false if it fails */  
         if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {          if (options.num_deny_groups > 0 || options.num_allow_groups > 0) {
                 grp = getgrgid(pw->pw_gid);                  /* Get the user's group access list (primary and supplementary) */
                 if (!grp)                  if (ga_init(pw->pw_name, pw->pw_gid) == 0)
                         return 0;                          return 0;
   
                 /* Return false if user's group is listed in DenyGroups */                  /* Return false if one of user's groups is listed in DenyGroups */
                 if (options.num_deny_groups > 0) {                  if (options.num_deny_groups > 0)
                         if (!grp->gr_name)                          if (ga_match(options.deny_groups,
                               options.num_deny_groups)) {
                                   ga_free();
                                 return 0;                                  return 0;
                         for (i = 0; i < options.num_deny_groups; i++)                          }
                                 if (match_pattern(grp->gr_name, options.deny_groups[i]))  
                                         return 0;  
                 }  
                 /*                  /*
                  * Return false if AllowGroups isn't empty and user's group                   * Return false if AllowGroups isn't empty and one of user's groups
                  * isn't listed there                   * isn't listed there
                  */                   */
                 if (options.num_allow_groups > 0) {                  if (options.num_allow_groups > 0)
                         if (!grp->gr_name)                          if (!ga_match(options.allow_groups,
                               options.num_allow_groups)) {
                                   ga_free();
                                 return 0;                                  return 0;
                         for (i = 0; i < options.num_allow_groups; i++)                          }
                                 if (match_pattern(grp->gr_name, options.allow_groups[i]))                  ga_free();
                                         break;  
                         /* i < options.num_allow_groups iff we break for  
                            loop */  
                         if (i >= options.num_allow_groups)  
                                 return 0;  
                 }  
         }          }
         /* We found no reason not to let this user try to log on... */          /* We found no reason not to let this user try to log on... */
         return 1;          return 1;
   }
   
   Authctxt *
   authctxt_new(void)
   {
           Authctxt *authctxt = xmalloc(sizeof(*authctxt));
           memset(authctxt, 0, sizeof(*authctxt));
           return authctxt;
   }
   
   void
   auth_log(Authctxt *authctxt, int authenticated, char *method, char *info)
   {
           void (*authlog) (const char *fmt,...) = verbose;
           char *authmsg;
   
           /* Raise logging level */
           if (authenticated == 1 ||
               !authctxt->valid ||
               authctxt->failures >= AUTH_FAIL_LOG ||
               strcmp(method, "password") == 0)
                   authlog = log;
   
           if (authctxt->postponed)
                   authmsg = "Postponed";
           else
                   authmsg = authenticated ? "Accepted" : "Failed";
   
           authlog("%s %s for %s%.100s from %.200s port %d%s",
               authmsg,
               method,
               authctxt->valid ? "" : "illegal user ",
               authctxt->valid && authctxt->pw->pw_uid == 0 ? "ROOT" : authctxt->user,
               get_remote_ipaddr(),
               get_remote_port(),
               info);
   }
   
   /*
    * Check whether root logins are disallowed.
    */
   int
   auth_root_allowed(char *method)
   {
           switch (options.permit_root_login) {
           case PERMIT_YES:
                   return 1;
                   break;
           case PERMIT_NO_PASSWD:
                   if (strcmp(method, "password") != 0)
                           return 1;
                   break;
           case PERMIT_FORCED_ONLY:
                   if (forced_command) {
                           log("Root login accepted for forced command.");
                           return 1;
                   }
                   break;
           }
           log("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
           return 0;
   }
   
   
   /*
    * Given a template and a passwd structure, build a filename
    * by substituting % tokenised options. Currently, %% becomes '%',
    * %h becomes the home directory and %u the username.
    *
    * This returns a buffer allocated by xmalloc.
    */
   char *
   expand_filename(const char *filename, struct passwd *pw)
   {
           Buffer buffer;
           char *file;
           const char *cp;
   
           /*
            * Build the filename string in the buffer by making the appropriate
            * substitutions to the given file name.
            */
           buffer_init(&buffer);
           for (cp = filename; *cp; cp++) {
                   if (cp[0] == '%' && cp[1] == '%') {
                           buffer_append(&buffer, "%", 1);
                           cp++;
                           continue;
                   }
                   if (cp[0] == '%' && cp[1] == 'h') {
                           buffer_append(&buffer, pw->pw_dir, strlen(pw->pw_dir));
                           cp++;
                           continue;
                   }
                   if (cp[0] == '%' && cp[1] == 'u') {
                           buffer_append(&buffer, pw->pw_name,
                                strlen(pw->pw_name));
                           cp++;
                           continue;
                   }
                   buffer_append(&buffer, cp, 1);
           }
           buffer_append(&buffer, "\0", 1);
   
           /*
            * Ensure that filename starts anchored. If not, be backward
            * compatible and prepend the '%h/'
            */
           file = xmalloc(MAXPATHLEN);
           cp = buffer_ptr(&buffer);
           if (*cp != '/')
                   snprintf(file, MAXPATHLEN, "%s/%s", pw->pw_dir, cp);
           else
                   strlcpy(file, cp, MAXPATHLEN);
   
           buffer_free(&buffer);
           return file;
   }
   
   char *
   authorized_keys_file(struct passwd *pw)
   {
           return expand_filename(options.authorized_keys_file, pw);
   }
   
   char *
   authorized_keys_file2(struct passwd *pw)
   {
           return expand_filename(options.authorized_keys_file2, pw);
   }
   
   /* return ok if key exists in sysfile or userfile */
   HostStatus
   check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host,
       const char *sysfile, const char *userfile)
   {
           Key *found;
           char *user_hostfile;
           struct stat st;
           int host_status;
   
           /* Check if we know the host and its host key. */
           found = key_new(key->type);
           host_status = check_host_in_hostfile(sysfile, host, key, found, NULL);
   
           if (host_status != HOST_OK && userfile != NULL) {
                   user_hostfile = tilde_expand_filename(userfile, pw->pw_uid);
                   if (options.strict_modes &&
                       (stat(user_hostfile, &st) == 0) &&
                       ((st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
                        (st.st_mode & 022) != 0)) {
                           log("Authentication refused for %.100s: "
                               "bad owner or modes for %.200s",
                               pw->pw_name, user_hostfile);
                   } else {
                           temporarily_use_uid(pw);
                           host_status = check_host_in_hostfile(user_hostfile,
                               host, key, found, NULL);
                           restore_uid();
                   }
                   xfree(user_hostfile);
           }
           key_free(found);
   
           debug2("check_key_in_hostfiles: key %s for %s", host_status == HOST_OK ?
               "ok" : "not found", host);
           return host_status;
   }
   
   
   /*
    * Check a given file for security. This is defined as all components
    * of the path to the file must either be owned by either the owner of
    * of the file or root and no directories must be group or world writable.
    *
    * XXX Should any specific check be done for sym links ?
    *
    * Takes an open file descriptor, the file name, a uid and and
    * error buffer plus max size as arguments.
    *
    * Returns 0 on success and -1 on failure
    */
   int
   secure_filename(FILE *f, const char *file, struct passwd *pw,
       char *err, size_t errlen)
   {
           uid_t uid = pw->pw_uid;
           char buf[MAXPATHLEN], homedir[MAXPATHLEN];
           char *cp;
           struct stat st;
   
           if (realpath(file, buf) == NULL) {
                   snprintf(err, errlen, "realpath %s failed: %s", file,
                       strerror(errno));
                   return -1;
           }
           if (realpath(pw->pw_dir, homedir) == NULL) {
                   snprintf(err, errlen, "realpath %s failed: %s", pw->pw_dir,
                       strerror(errno));
                   return -1;
           }
   
           /* check the open file to avoid races */
           if (fstat(fileno(f), &st) < 0 ||
               (st.st_uid != 0 && st.st_uid != uid) ||
               (st.st_mode & 022) != 0) {
                   snprintf(err, errlen, "bad ownership or modes for file %s",
                       buf);
                   return -1;
           }
   
           /* for each component of the canonical path, walking upwards */
           for (;;) {
                   if ((cp = dirname(buf)) == NULL) {
                           snprintf(err, errlen, "dirname() failed");
                           return -1;
                   }
                   strlcpy(buf, cp, sizeof(buf));
   
                   debug3("secure_filename: checking '%s'", buf);
                   if (stat(buf, &st) < 0 ||
                       (st.st_uid != 0 && st.st_uid != uid) ||
                       (st.st_mode & 022) != 0) {
                           snprintf(err, errlen,
                               "bad ownership or modes for directory %s", buf);
                           return -1;
                   }
   
                   /* If are passed the homedir then we can stop */
                   if (strcmp(homedir, buf) == 0) {
                           debug3("secure_filename: terminating check at '%s'",
                               buf);
                           break;
                   }
                   /*
                    * dirname should always complete with a "/" path,
                    * but we can be paranoid and check for "." too
                    */
                   if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
                           break;
           }
           return 0;
 }  }
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