X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/8efc0c151a0f57612e1aa0abb5b7d536db4cf76a..HEAD:/auth-rhosts.c diff --git a/auth-rhosts.c b/auth-rhosts.c index 62c64c0a..5c129670 100644 --- a/auth-rhosts.c +++ b/auth-rhosts.c @@ -1,298 +1,327 @@ +/* $OpenBSD: auth-rhosts.c,v 1.43 2008/06/13 14:18:51 dtucker Exp $ */ /* + * Author: Tatu Ylonen + * Copyright (c) 1995 Tatu Ylonen , Espoo, Finland + * All rights reserved + * Rhosts authentication. This file contains code to check whether to admit + * the login based on rhosts authentication. This file also processes + * /etc/hosts.equiv. + * + * 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". + */ -auth-rhosts.c - -Author: Tatu Ylonen - -Copyright (c) 1995 Tatu Ylonen , Espoo, Finland - All rights reserved - -Created: Fri Mar 17 05:12:18 1995 ylo - -Rhosts authentication. This file contains code to check whether to admit -the login based on rhosts authentication. This file also processes -/etc/hosts.equiv. +#include "includes.h" -*/ +#include +#include -#include "includes.h" -RCSID("$Id$"); +#ifdef HAVE_NETGROUP_H +# include +#endif +#include +#include +#include +#include +#include +#include #include "packet.h" -#include "ssh.h" -#include "xmalloc.h" +#include "buffer.h" #include "uidswap.h" +#include "pathnames.h" +#include "log.h" +#include "servconf.h" +#include "canohost.h" +#include "key.h" +#include "hostfile.h" +#include "auth.h" +#include "misc.h" + +/* import */ +extern ServerOptions options; +extern int use_privsep; -/* This function processes an rhosts-style file (.rhosts, .shosts, or - /etc/hosts.equiv). This returns true if authentication can be granted - based on the file, and returns zero otherwise. */ - -int check_rhosts_file(const char *filename, const char *hostname, - const char *ipaddr, const char *client_user, - const char *server_user) +/* + * This function processes an rhosts-style file (.rhosts, .shosts, or + * /etc/hosts.equiv). This returns true if authentication can be granted + * based on the file, and returns zero otherwise. + */ + +static int +check_rhosts_file(const char *filename, const char *hostname, + const char *ipaddr, const char *client_user, + const char *server_user) { - FILE *f; - char buf[1024]; /* Must not be larger than host, user, dummy below. */ - - /* Open the .rhosts file. */ - f = fopen(filename, "r"); - if (!f) - return 0; /* Cannot read the .rhosts - deny access. */ - - /* Go through the file, checking every entry. */ - while (fgets(buf, sizeof(buf), f)) - { - /* All three must be at least as big as buf to avoid overflows. */ - char hostbuf[1024], userbuf[1024], dummy[1024], *host, *user, *cp; - int negated; - - for (cp = buf; *cp == ' ' || *cp == '\t'; cp++) - ; - if (*cp == '#' || *cp == '\n' || !*cp) - continue; - - /* NO_PLUS is supported at least on OSF/1. We skip it (we don't ever - support the plus syntax). */ - if (strncmp(cp, "NO_PLUS", 7) == 0) - continue; - - /* This should be safe because each buffer is as big as the whole - string, and thus cannot be overwritten. */ - switch (sscanf(buf, "%s %s %s", hostbuf, userbuf, dummy)) - { - case 0: - packet_send_debug("Found empty line in %.100s.", filename); - continue; /* Empty line? */ - case 1: - /* Host name only. */ - strlcpy(userbuf, server_user, sizeof(userbuf)); - break; - case 2: - /* Got both host and user name. */ - break; - case 3: - packet_send_debug("Found garbage in %.100s.", filename); - continue; /* Extra garbage */ - default: - continue; /* Weird... */ + FILE *f; + char buf[1024]; /* Must not be larger than host, user, dummy below. */ + int fd; + struct stat st; + + /* Open the .rhosts file, deny if unreadable */ + if ((fd = open(filename, O_RDONLY|O_NONBLOCK)) == -1) + return 0; + if (fstat(fd, &st) == -1) { + close(fd); + return 0; } - - host = hostbuf; - user = userbuf; - negated = 0; - - /* Process negated host names, or positive netgroups. */ - if (host[0] == '-') - { - negated = 1; - host++; + if (!S_ISREG(st.st_mode)) { + logit("User %s hosts file %s is not a regular file", + server_user, filename); + close(fd); + return 0; } - else - if (host[0] == '+') - host++; - - if (user[0] == '-') - { - negated = 1; - user++; + unset_nonblock(fd); + if ((f = fdopen(fd, "r")) == NULL) { + close(fd); + return 0; } - else - if (user[0] == '+') - user++; - - /* Check for empty host/user names (particularly '+'). */ - if (!host[0] || !user[0]) - { - /* We come here if either was '+' or '-'. */ - packet_send_debug("Ignoring wild host/user names in %.100s.", + while (fgets(buf, sizeof(buf), f)) { + /* All three must be at least as big as buf to avoid overflows. */ + char hostbuf[1024], userbuf[1024], dummy[1024], *host, *user, *cp; + int negated; + + for (cp = buf; *cp == ' ' || *cp == '\t'; cp++) + ; + if (*cp == '#' || *cp == '\n' || !*cp) + continue; + + /* + * NO_PLUS is supported at least on OSF/1. We skip it (we + * don't ever support the plus syntax). + */ + if (strncmp(cp, "NO_PLUS", 7) == 0) + continue; + + /* + * This should be safe because each buffer is as big as the + * whole string, and thus cannot be overwritten. + */ + switch (sscanf(buf, "%1023s %1023s %1023s", hostbuf, userbuf, + dummy)) { + case 0: + auth_debug_add("Found empty line in %.100s.", filename); + continue; + case 1: + /* Host name only. */ + strlcpy(userbuf, server_user, sizeof(userbuf)); + break; + case 2: + /* Got both host and user name. */ + break; + case 3: + auth_debug_add("Found garbage in %.100s.", filename); + continue; + default: + /* Weird... */ + continue; + } + + host = hostbuf; + user = userbuf; + negated = 0; + + /* Process negated host names, or positive netgroups. */ + if (host[0] == '-') { + negated = 1; + host++; + } else if (host[0] == '+') + host++; + + if (user[0] == '-') { + negated = 1; + user++; + } else if (user[0] == '+') + user++; + + /* Check for empty host/user names (particularly '+'). */ + if (!host[0] || !user[0]) { + /* We come here if either was '+' or '-'. */ + auth_debug_add("Ignoring wild host/user names in %.100s.", filename); - continue; - } - - /* Verify that host name matches. */ - if (host[0] == '@') - { - if (!innetgr(host + 1, hostname, NULL, NULL) && - !innetgr(host + 1, ipaddr, NULL, NULL)) - continue; - } - else - if (strcasecmp(host, hostname) && strcmp(host, ipaddr) != 0) - continue; /* Different hostname. */ - - /* Verify that user name matches. */ - if (user[0] == '@') - { - if (!innetgr(user + 1, NULL, client_user, NULL)) - continue; - } - else - if (strcmp(user, client_user) != 0) - continue; /* Different username. */ - - /* Found the user and host. */ - fclose(f); - - /* If the entry was negated, deny access. */ - if (negated) - { - packet_send_debug("Matched negative entry in %.100s.", + continue; + } + /* Verify that host name matches. */ + if (host[0] == '@') { + if (!innetgr(host + 1, hostname, NULL, NULL) && + !innetgr(host + 1, ipaddr, NULL, NULL)) + continue; + } else if (strcasecmp(host, hostname) && strcmp(host, ipaddr) != 0) + continue; /* Different hostname. */ + + /* Verify that user name matches. */ + if (user[0] == '@') { + if (!innetgr(user + 1, NULL, client_user, NULL)) + continue; + } else if (strcmp(user, client_user) != 0) + continue; /* Different username. */ + + /* Found the user and host. */ + fclose(f); + + /* If the entry was negated, deny access. */ + if (negated) { + auth_debug_add("Matched negative entry in %.100s.", filename); - return 0; + return 0; + } + /* Accept authentication. */ + return 1; } - /* Accept authentication. */ - return 1; - } - - /* Authentication using this file denied. */ - fclose(f); - return 0; + /* Authentication using this file denied. */ + fclose(f); + return 0; } -/* Tries to authenticate the user using the .shosts or .rhosts file. - Returns true if authentication succeeds. If ignore_rhosts is - true, only /etc/hosts.equiv will be considered (.rhosts and .shosts - are ignored). */ +/* + * Tries to authenticate the user using the .shosts or .rhosts file. Returns + * true if authentication succeeds. If ignore_rhosts is true, only + * /etc/hosts.equiv will be considered (.rhosts and .shosts are ignored). + */ -int auth_rhosts(struct passwd *pw, const char *client_user, - int ignore_rhosts, int strict_modes) +int +auth_rhosts(struct passwd *pw, const char *client_user) { - char buf[1024]; - const char *hostname, *ipaddr; - int port; - struct stat st; - static const char *rhosts_files[] = { ".shosts", ".rhosts", NULL }; - unsigned int rhosts_file_index; - - /* Quick check: if the user has no .shosts or .rhosts files, return failure - immediately without doing costly lookups from name servers. */ - /* Switch to the user's uid. */ - temporarily_use_uid(pw->pw_uid); - for (rhosts_file_index = 0; rhosts_files[rhosts_file_index]; - rhosts_file_index++) - { - /* Check users .rhosts or .shosts. */ - snprintf(buf, sizeof buf, "%.500s/%.100s", - pw->pw_dir, rhosts_files[rhosts_file_index]); - if (stat(buf, &st) >= 0) - break; - } - /* Switch back to privileged uid. */ - restore_uid(); - - if (!rhosts_files[rhosts_file_index] && stat("/etc/hosts.equiv", &st) < 0 && - stat(SSH_HOSTS_EQUIV, &st) < 0) - return 0; /* The user has no .shosts or .rhosts file and there are no - system-wide files. */ - - /* Get the name, address, and port of the remote host. */ - hostname = get_canonical_hostname(); - ipaddr = get_remote_ipaddr(); - port = get_remote_port(); - - /* Check that the connection comes from a privileged port. - Rhosts authentication only makes sense for priviledged programs. - Of course, if the intruder has root access on his local machine, - he can connect from any port. So do not use .rhosts - authentication from machines that you do not trust. */ - if (port >= IPPORT_RESERVED || - port < IPPORT_RESERVED / 2) - { - log("Connection from %.100s from nonpriviledged port %d", - hostname, port); - packet_send_debug("Your ssh client is not running as root."); - return 0; - } - - /* If not logging in as superuser, try /etc/hosts.equiv and shosts.equiv. */ - if (pw->pw_uid != 0) - { - if (check_rhosts_file("/etc/hosts.equiv", hostname, ipaddr, client_user, - pw->pw_name)) - { - packet_send_debug("Accepted for %.100s [%.100s] by /etc/hosts.equiv.", + const char *hostname, *ipaddr; + + hostname = get_canonical_hostname(options.use_dns); + ipaddr = get_remote_ipaddr(); + return auth_rhosts2(pw, client_user, hostname, ipaddr); +} + +static int +auth_rhosts2_raw(struct passwd *pw, const char *client_user, const char *hostname, + const char *ipaddr) +{ + char buf[1024]; + struct stat st; + static const char *rhosts_files[] = {".shosts", ".rhosts", NULL}; + u_int rhosts_file_index; + + debug2("auth_rhosts2: clientuser %s hostname %s ipaddr %s", + client_user, hostname, ipaddr); + + /* Switch to the user's uid. */ + temporarily_use_uid(pw); + /* + * Quick check: if the user has no .shosts or .rhosts files, return + * failure immediately without doing costly lookups from name + * servers. + */ + for (rhosts_file_index = 0; rhosts_files[rhosts_file_index]; + rhosts_file_index++) { + /* Check users .rhosts or .shosts. */ + snprintf(buf, sizeof buf, "%.500s/%.100s", + pw->pw_dir, rhosts_files[rhosts_file_index]); + if (stat(buf, &st) >= 0) + break; + } + /* Switch back to privileged uid. */ + restore_uid(); + + /* Deny if The user has no .shosts or .rhosts file and there are no system-wide files. */ + if (!rhosts_files[rhosts_file_index] && + stat(_PATH_RHOSTS_EQUIV, &st) < 0 && + stat(_PATH_SSH_HOSTS_EQUIV, &st) < 0) + return 0; + + /* If not logging in as superuser, try /etc/hosts.equiv and shosts.equiv. */ + if (pw->pw_uid != 0) { + if (check_rhosts_file(_PATH_RHOSTS_EQUIV, hostname, ipaddr, + client_user, pw->pw_name)) { + auth_debug_add("Accepted for %.100s [%.100s] by /etc/hosts.equiv.", hostname, ipaddr); - return 1; + return 1; + } + if (check_rhosts_file(_PATH_SSH_HOSTS_EQUIV, hostname, ipaddr, + client_user, pw->pw_name)) { + auth_debug_add("Accepted for %.100s [%.100s] by %.100s.", + hostname, ipaddr, _PATH_SSH_HOSTS_EQUIV); + return 1; + } } - if (check_rhosts_file(SSH_HOSTS_EQUIV, hostname, ipaddr, client_user, - pw->pw_name)) - { - packet_send_debug("Accepted for %.100s [%.100s] by %.100s.", - hostname, ipaddr, SSH_HOSTS_EQUIV); - return 1; + /* + * Check that the home directory is owned by root or the user, and is + * not group or world writable. + */ + if (stat(pw->pw_dir, &st) < 0) { + logit("Rhosts authentication refused for %.100s: " + "no home directory %.200s", pw->pw_name, pw->pw_dir); + auth_debug_add("Rhosts authentication refused for %.100s: " + "no home directory %.200s", pw->pw_name, pw->pw_dir); + return 0; } - } - - /* Check that the home directory is owned by root or the user, and is not - group or world writable. */ - if (stat(pw->pw_dir, &st) < 0) - { - log("Rhosts authentication refused for %.100: no home directory %.200s", - pw->pw_name, pw->pw_dir); - packet_send_debug("Rhosts authentication refused for %.100: no home directory %.200s", - pw->pw_name, pw->pw_dir); - return 0; - } - if (strict_modes && - ((st.st_uid != 0 && st.st_uid != pw->pw_uid) || - (st.st_mode & 022) != 0)) - { - log("Rhosts authentication refused for %.100s: bad ownership or modes for home directory.", - pw->pw_name); - packet_send_debug("Rhosts authentication refused for %.100s: bad ownership or modes for home directory.", - pw->pw_name); - return 0; - } - - /* Check all .rhosts files (currently .shosts and .rhosts). */ - /* Temporarily use the user's uid. */ - temporarily_use_uid(pw->pw_uid); - for (rhosts_file_index = 0; rhosts_files[rhosts_file_index]; - rhosts_file_index++) - { - /* Check users .rhosts or .shosts. */ - snprintf(buf, sizeof buf, "%.500s/%.100s", - pw->pw_dir, rhosts_files[rhosts_file_index]); - if (stat(buf, &st) < 0) - continue; /* No such file. */ - - /* Make sure that the file is either owned by the user or by root, - and make sure it is not writable by anyone but the owner. This is - to help avoid novices accidentally allowing access to their account - by anyone. */ - if (strict_modes && - ((st.st_uid != 0 && st.st_uid != pw->pw_uid) || - (st.st_mode & 022) != 0)) - { - log("Rhosts authentication refused for %.100s: bad modes for %.200s", - pw->pw_name, buf); - packet_send_debug("Bad file modes for %.200s", buf); - continue; + if (options.strict_modes && + ((st.st_uid != 0 && st.st_uid != pw->pw_uid) || + (st.st_mode & 022) != 0)) { + logit("Rhosts authentication refused for %.100s: " + "bad ownership or modes for home directory.", pw->pw_name); + auth_debug_add("Rhosts authentication refused for %.100s: " + "bad ownership or modes for home directory.", pw->pw_name); + return 0; } - - /* Check if we have been configured to ignore .rhosts and .shosts - files. */ - if (ignore_rhosts) - { - packet_send_debug("Server has been configured to ignore %.100s.", + /* Temporarily use the user's uid. */ + temporarily_use_uid(pw); + + /* Check all .rhosts files (currently .shosts and .rhosts). */ + for (rhosts_file_index = 0; rhosts_files[rhosts_file_index]; + rhosts_file_index++) { + /* Check users .rhosts or .shosts. */ + snprintf(buf, sizeof buf, "%.500s/%.100s", + pw->pw_dir, rhosts_files[rhosts_file_index]); + if (stat(buf, &st) < 0) + continue; + + /* + * Make sure that the file is either owned by the user or by + * root, and make sure it is not writable by anyone but the + * owner. This is to help avoid novices accidentally + * allowing access to their account by anyone. + */ + if (options.strict_modes && + ((st.st_uid != 0 && st.st_uid != pw->pw_uid) || + (st.st_mode & 022) != 0)) { + logit("Rhosts authentication refused for %.100s: bad modes for %.200s", + pw->pw_name, buf); + auth_debug_add("Bad file modes for %.200s", buf); + continue; + } + /* Check if we have been configured to ignore .rhosts and .shosts files. */ + if (options.ignore_rhosts) { + auth_debug_add("Server has been configured to ignore %.100s.", rhosts_files[rhosts_file_index]); - continue; - } - - /* Check if authentication is permitted by the file. */ - if (check_rhosts_file(buf, hostname, ipaddr, client_user, pw->pw_name)) - { - packet_send_debug("Accepted by %.100s.", + continue; + } + /* Check if authentication is permitted by the file. */ + if (check_rhosts_file(buf, hostname, ipaddr, client_user, pw->pw_name)) { + auth_debug_add("Accepted by %.100s.", rhosts_files[rhosts_file_index]); - /* Restore the privileged uid. */ - restore_uid(); - return 1; + /* Restore the privileged uid. */ + restore_uid(); + auth_debug_add("Accepted host %s ip %s client_user %s server_user %s", + hostname, ipaddr, client_user, pw->pw_name); + return 1; + } } - } - /* Rhosts authentication denied. */ - /* Restore the privileged uid. */ - restore_uid(); - return 0; + /* Restore the privileged uid. */ + restore_uid(); + return 0; +} + +int +auth_rhosts2(struct passwd *pw, const char *client_user, const char *hostname, + const char *ipaddr) +{ + int ret; + + auth_debug_reset(); + ret = auth_rhosts2_raw(pw, client_user, hostname, ipaddr); + if (!use_privsep) + auth_debug_send(); + return ret; }