diff options
Diffstat (limited to 'modules/pam_rhosts/pam_rhosts_auth.c')
| -rw-r--r-- | modules/pam_rhosts/pam_rhosts_auth.c | 829 |
1 files changed, 829 insertions, 0 deletions
diff --git a/modules/pam_rhosts/pam_rhosts_auth.c b/modules/pam_rhosts/pam_rhosts_auth.c new file mode 100644 index 00000000..f9707cfc --- /dev/null +++ b/modules/pam_rhosts/pam_rhosts_auth.c @@ -0,0 +1,829 @@ +/*---------------------------------------------------------------------- + * Modified for Linux-PAM by Al Longyear <longyear@netcom.com> 96/5/5 + * Modifications, Cristian Gafton 97/2/8 + * Modifications, Peter Allgeyer 97/3 + * Modifications (netgroups and fixes), Nicolai Langfeldt 97/3/21 + * Security fix: 97/10/2 - gethostbyname called repeatedly without care + * Modification (added privategroup option) Andrew <morgan@transmeta.com> + *---------------------------------------------------------------------- + * Copyright (c) 1983, 1993, 1994 + * The Regents of the University of California. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by the University of + * California, Berkeley and its contributors. + * 4. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#define _BSD_SOURCE + +#define USER_RHOSTS_FILE "/.rhosts" /* prefixed by user's home dir */ + +#ifdef linux +#include <endian.h> +#endif + +#ifdef NEED_FSUID_H +#include <sys/fsuid.h> +#endif /* NEED_FSUID_H */ + +#include <sys/types.h> +#include <sys/uio.h> +#include <string.h> +#include <unistd.h> +#include <stdlib.h> +#include <sys/param.h> +#include <sys/socket.h> +#include <netinet/in.h> +#include <netdb.h> /* This is supposed(?) to contain the following */ +int innetgr(const char *, const char *, const char *,const char *); + +#include <stdio.h> +#include <errno.h> +#include <sys/time.h> +#include <arpa/inet.h> + +#ifndef MAXDNAME +#define MAXDNAME 256 +#endif + +#include <stdarg.h> +#include <ctype.h> + +#include <net/if.h> +#ifdef linux +# include <linux/sockios.h> +# ifndef __USE_MISC +# define __USE_MISC +# include <sys/fsuid.h> +# endif /* __USE_MISC */ +#endif + +#include <pwd.h> +#include <grp.h> +#include <sys/file.h> +#include <sys/signal.h> +#include <sys/stat.h> +#include <syslog.h> +#ifndef _PATH_HEQUIV +#define _PATH_HEQUIV "/etc/hosts.equiv" +#endif /* _PATH_HEQUIV */ + +#define PAM_SM_AUTH /* only defines this management group */ + +#include <security/pam_modules.h> +#include <security/_pam_macros.h> + +/* to the best of my knowledge, all modern UNIX boxes have 32 bit integers */ +#define U32 unsigned int + + +/* + * Options for this module + */ + +struct _options { + int opt_no_hosts_equiv; + int opt_hosts_equiv_rootok; + int opt_no_rhosts; + int opt_debug; + int opt_nowarn; + int opt_disallow_null_authtok; + int opt_silent; + int opt_promiscuous; + int opt_suppress; + int opt_private_group; + int opt_no_uid_check; + const char *superuser; + const char *last_error; +}; + +/* logging */ +static void _pam_log(int err, const char *format, ...) +{ + va_list args; + + va_start(args, format); + openlog("pam_rhosts_auth", LOG_CONS|LOG_PID, LOG_AUTH); + vsyslog(err, format, args); + va_end(args); + closelog(); +} + +static void set_option (struct _options *opts, const char *arg) +{ + if (strcmp(arg, "no_hosts_equiv") == 0) { + opts->opt_no_hosts_equiv = 1; + return; + } + + if (strcmp(arg, "hosts_equiv_rootok") == 0) { + opts->opt_hosts_equiv_rootok = 1; + return; + } + + if (strcmp(arg, "no_rhosts") == 0) { + opts->opt_no_rhosts = 1; + return; + } + + if (strcmp(arg, "debug") == 0) { + D(("debugging enabled")); + opts->opt_debug = 1; + return; + } + + if (strcmp(arg, "no_warn") == 0) { + opts->opt_nowarn = 1; + return; + } + + if (strcmp(arg, "promiscuous") == 0) { + opts->opt_promiscuous = 1; /* used to permit '+' in ...hosts file */ + return; + } + + if (strcmp(arg, "suppress") == 0) { + opts->opt_suppress = 1; /* used to suppress failure warning message */ + return; + } + + if (strcmp(arg, "privategroup") == 0) { + opts->opt_private_group = 1; /* used to permit group write on .rhosts + file if group has same name as owner */ + return; + } + + if (strcmp(arg, "no_uid_check") == 0) { + opts->opt_no_uid_check = 1; /* NIS optimization */ + return; + } + + if (strcmp(arg, "superuser=") == 0) { + opts->superuser = arg+sizeof("superuser=")-1; + return; + } + /* + * All other options are ignored at the present time. + */ + _pam_log(LOG_WARNING, "unrecognized option '%s'", arg); +} + +static void set_parameters (struct _options *opts, int flags, + int argc, const char **argv) +{ + opts->opt_silent = flags & PAM_SILENT; + opts->opt_disallow_null_authtok = flags & PAM_DISALLOW_NULL_AUTHTOK; + + while (argc-- > 0) { + set_option (opts, *argv); + ++argv; + } +} + +/* + * Obtain the name of the remote host. Currently, this is simply by + * requesting the contents of the PAM_RHOST item. + */ + +static int pam_get_rhost(pam_handle_t *pamh, const char **rhost + , const char *prompt) +{ + int retval; + const char *current; + + retval = pam_get_item (pamh, PAM_RHOST, (const void **)¤t); + if (retval != PAM_SUCCESS) + return retval; + + if (current == NULL) { + return PAM_AUTH_ERR; + } + *rhost = current; + + return retval; /* pass on any error from conversation */ +} + +/* + * Obtain the name of the remote user. Currently, this is simply by + * requesting the contents of the PAM_RUSER item. + */ + +static int pam_get_ruser(pam_handle_t *pamh, const char **ruser + , const char *prompt) +{ + int retval; + const char *current; + + retval = pam_get_item (pamh, PAM_RUSER, (const void **)¤t); + if (retval != PAM_SUCCESS) + return retval; + + if (current == NULL) { + return PAM_AUTH_ERR; + } + *ruser = current; + + return retval; /* pass on any error from conversation */ +} + +/* + * Returns 1 if positive match, 0 if no match, -1 if negative match. + */ + +static int +__icheckhost (pam_handle_t *pamh, struct _options *opts, U32 raddr + , register char *lhost, const char *rhost) +{ + struct hostent *hp; + U32 laddr; + int negate=1; /* Multiply return with this to get -1 instead of 1 */ + char **pp, *user; + + /* Check nis netgroup. We assume that pam has done all needed + paranoia checking before we are handed the rhost */ + if (strncmp("+@",lhost,2) == 0) + return(innetgr(&lhost[2],rhost,NULL,NULL)); + + if (strncmp("-@",lhost,2) == 0) + return(-innetgr(&lhost[2],rhost,NULL,NULL)); + + /* -host */ + if (strncmp("-",lhost,1) == 0) { + negate=-1; + lhost++; + } else if (strcmp("+",lhost) == 0) { + (void) pam_get_item(pamh, PAM_USER, (const void **)&user); + D(("user %s has a `+' host entry", user)); + if (opts->opt_promiscuous) + return (1); /* asking for trouble, but ok.. */ + /* If not promiscuous: handle as negative */ + return (-1); + } + + /* Try for raw ip address first. */ + if (isdigit(*lhost) && (long)(laddr = inet_addr(lhost)) != -1) + return (negate*(! (raddr ^ laddr))); + + /* Better be a hostname. */ + hp = gethostbyname(lhost); + if (hp == NULL) + return (0); + + /* Spin through ip addresses. */ + for (pp = hp->h_addr_list; *pp; ++pp) + if (!memcmp (&raddr, *pp, sizeof (U32))) + return (negate); + + /* No match. */ + return (0); +} + +/* Returns 1 on positive match, 0 on no match, -1 on negative match */ + +static int __icheckuser(pam_handle_t *pamh, struct _options *opts + , const char *luser, const char *ruser + , const char *rhost) +{ + /* + luser is user entry from .rhosts/hosts.equiv file + ruser is user id on remote host + rhost is the remote host name + */ + char *user; + + /* [-+]@netgroup */ + if (strncmp("+@",luser,2) == 0) + return (innetgr(&luser[2],NULL,ruser,NULL)); + + if (strncmp("-@",luser,2) == 0) + return (-innetgr(&luser[2],NULL,ruser,NULL)); + + /* -user */ + if (strncmp("-",luser,1) == 0) + return(-(strcmp(&luser[1],ruser) == 0)); + + /* + */ + if (strcmp("+",luser) == 0) { + (void) pam_get_item(pamh, PAM_USER, (const void **)&user); + _pam_log(LOG_WARNING, "user %s has a `+' user entry", user); + if (opts->opt_promiscuous) + return(1); + /* If not promiscuous we handle it as a negative match */ + return(-1); + } + + /* simple string match */ + return (strcmp(ruser, luser) == 0); +} + +/* + * Returns 1 for blank lines (or only comment lines) and 0 otherwise + */ + +static int __isempty(char *p) +{ + while (*p && isspace(*p)) { + ++p; + } + + return (*p == '\0' || *p == '#') ? 1:0 ; +} + +/* + * Returns 0 if positive match, 1 if _not_ ok. + */ + +static int +__ivaliduser (pam_handle_t *pamh, struct _options *opts, + FILE *hostf, U32 raddr, + const char *luser, const char *ruser, const char *rhost) +{ + register const char *user; + register char *p; + int hcheck, ucheck; + char buf[MAXHOSTNAMELEN + 128]; /* host + login */ + + buf[sizeof (buf)-1] = '\0'; /* terminate line */ + + while (fgets(buf, sizeof(buf), hostf) != NULL) { /* hostf file line */ + p = buf; /* from beginning of file.. */ + + /* Skip empty or comment lines */ + if (__isempty(p)) { + continue; + } + + /* Skip lines that are too long. */ + if (strchr(p, '\n') == NULL) { + int ch = getc(hostf); + + while (ch != '\n' && ch != EOF) + ch = getc(hostf); + continue; + } + + /* + * If there is a hostname at the start of the line. Set it to + * lower case. A leading ' ' or '\t' indicates no hostname + */ + + for (;*p && !isspace(*p); ++p) { + *p = tolower(*p); + } + + /* + * next we want to find the permitted name for the remote user + */ + + if (*p == ' ' || *p == '\t') { + + /* <nul> terminate hostname and skip spaces */ + for (*p++='\0'; *p && isspace(*p); ++p); + + user = p; /* this is the user's name */ + while (*p && !isspace(*p)) + ++p; /* find end of user's name */ + } else + user = p; + + *p = '\0'; /* <nul> terminate username (+host?) */ + + /* buf -> host(?) ; user -> username(?) */ + + /* First check host part */ + hcheck=__icheckhost(pamh, opts, raddr, buf, rhost); + + if (hcheck<0) + return(1); + + if (hcheck) { + /* Then check user part */ + if (! (*user)) + user = luser; + + ucheck=__icheckuser(pamh, opts, user, ruser, rhost); + + /* Positive 'host user' match? */ + if (ucheck>0) + return(0); + + /* Negative 'host -user' match? */ + if (ucheck<0) + return(1); + + /* Neither, go on looking for match */ + } + } + + return (1); +} + +/* + * New .rhosts strategy: We are passed an ip address. We spin through + * hosts.equiv and .rhosts looking for a match. When the .rhosts only + * has ip addresses, we don't have to trust a nameserver. When it + * contains hostnames, we spin through the list of addresses the nameserver + * gives us and look for a match. + * + * Returns 0 if ok, -1 if not ok. + */ + +static int +pam_iruserok(pam_handle_t *pamh, + struct _options *opts, U32 raddr, int superuser, + const char *ruser, const char *luser, const char *rhost) +{ + const char *cp; + struct stat sbuf; + struct passwd *pwd; + FILE *hostf; + uid_t uid; + int answer; + char pbuf[MAXPATHLEN]; /* potential buffer overrun */ + + if ((!superuser||opts->opt_hosts_equiv_rootok) && !opts->opt_no_hosts_equiv ) { + + /* try to open system hosts.equiv file */ + hostf = fopen (_PATH_HEQUIV, "r"); + if (hostf) { + answer = __ivaliduser(pamh, opts, hostf, raddr, luser + , ruser, rhost); + (void) fclose(hostf); + if (answer == 0) + return 0; /* remote host is equivalent to localhost */ + } /* else { + No hosts.equiv file on system. + } */ + } + + if ( opts->opt_no_rhosts ) + return 1; + + /* + * Identify user's local .rhosts file + */ + + pwd = getpwnam(luser); + if (pwd == NULL) { + /* + * luser is assumed to be valid because of an earlier check for uid = 0 + * we don't log this error twice. However, this shouldn't happen ! + * --cristiang + */ + return(1); + } + + /* check for buffer overrun */ + if (strlen(pwd->pw_dir) + sizeof(USER_RHOSTS_FILE) + 2 >= MAXPATHLEN) { + if (opts->opt_debug) + _pam_log(LOG_DEBUG,"home directory for `%s' is too long", luser); + return 1; /* to dangerous to try */ + } + + (void) strcpy(pbuf, pwd->pw_dir); + (void) strcat(pbuf, USER_RHOSTS_FILE); + + /* + * Change effective uid while _reading_ .rhosts. (not just + * opening). If root and reading an NFS mounted file system, + * can't read files that are 0600 as .rhosts files should be. + */ + + /* We are root, this will not fail */ +#ifdef linux + /* If we are on linux the better way is setfsuid */ + uid = setfsuid(pwd->pw_uid); + hostf = fopen(pbuf, "r"); +#else + uid = geteuid(); + (void) seteuid(pwd->pw_uid); + hostf = fopen(pbuf, "r"); +#endif + + if (hostf == NULL) { + if (opts->opt_debug) + _pam_log(LOG_DEBUG,"Could not open %s file",pbuf); + answer = 1; + goto exit_function; + } + + /* + * If not a regular file, or is owned by someone other than + * user or root or if writeable by anyone but the owner, quit. + */ + + cp = NULL; + if (lstat(pbuf, &sbuf) < 0 || !S_ISREG(sbuf.st_mode)) + cp = ".rhosts not regular file"; + else if (fstat(fileno(hostf), &sbuf) < 0) + cp = ".rhosts fstat failed"; + else if (sbuf.st_uid && sbuf.st_uid != pwd->pw_uid) + cp = "bad .rhosts owner"; + else if (sbuf.st_mode & S_IWOTH) + cp = ".rhosts writable by other!"; + else if (sbuf.st_mode & S_IWGRP) { + + /* private group caveat */ + if (opts->opt_private_group) { + struct group *grp = getgrgid(sbuf.st_gid); + + if (NULL == grp || NULL == grp->gr_name + || strcmp(luser,grp->gr_name)) { + cp = ".rhosts writable by public group"; + } else if (grp->gr_mem) { + int gcount; + + /* require at most one member (luser) of this group */ + for (gcount=0; grp->gr_mem[gcount]; ++gcount) { + if (strcmp(grp->gr_mem[gcount], luser)) { + gcount = -1; + break; + } + } + if (gcount < 0) { + cp = ".rhosts writable by other members of group"; + } + } + } else { + cp = ".rhosts writable by group"; + } + + } /* It is _NOT_ safe to append an else here... Do so prior to + * S_IWGRP check */ + + /* If there were any problems, quit. */ + if (cp) { + opts->last_error = cp; + answer = 1; + goto exit_function; + } + + answer = __ivaliduser (pamh, opts, hostf, raddr, luser, ruser, rhost); + +exit_function: + /* + * Go here to exit after the fsuid/euid has been adjusted so that + * they are reset before we exit. + */ + +#ifdef linux + setfsuid(uid); +#else + (void)seteuid(uid); +#endif + + if (hostf != NULL) + (void) fclose(hostf); + + return answer; +} + +static int +pam_ruserok (pam_handle_t *pamh, + struct _options *opts, const char *rhost, int superuser, + const char *ruser, const char *luser) +{ + struct hostent *hp; + int answer = 1; /* default to failure */ + U32 *addrs; + int n, i; + + opts->last_error = (char *) 0; + hp = gethostbyname(rhost); /* identify host */ + + if (hp != NULL) { + /* First of all check the address length */ + if (hp->h_length != 4) { + _pam_log(LOG_ALERT, "pam_rhosts module can't work with not IPv4 " + "addresses"); + return 1; /* not allowed */ + } + + /* loop though address list */ + for (n = 0; hp->h_addr_list[n]; n++); + D(("rhosts: %d addresses", n)); + + if (n) { + addrs = calloc (n, hp->h_length); + for (i = 0; i < n; i++) + memcpy (addrs+i, hp->h_addr_list[i], hp->h_length); + + for (i = 0; i < n && answer; i++) { + D(("rhosts: address %d is %04x", i, addrs[i])); + answer = pam_iruserok(pamh, opts, addrs[i], superuser, + ruser, luser, rhost); + /* answer == 0 means success */ + } + + free (addrs); + } + } + + return answer; +} + +/* + * Internal function to do authentication + */ + +static int _pam_auth_rhosts (pam_handle_t *pamh, + int flags, + int argc, + const char **argv) +{ + int retval; + const char *luser; + const char *ruser,*rhost; + struct _options opts; + int as_root = 0; + /* + * Look at the options and set the flags accordingly. + */ + memset (&opts, 0, sizeof (opts)); + set_parameters (&opts, flags, argc, argv); + /* + * Obtain the parameters for the various items + */ + for (;;) { /* abuse loop to avoid goto */ + + /* get the remotehost */ + retval = pam_get_rhost(pamh, &rhost, NULL); + (void) pam_set_item(pamh, PAM_RHOST, rhost); + if (retval != PAM_SUCCESS) { + if (opts.opt_debug) { + _pam_log(LOG_DEBUG, "could not get the remote host name"); + } + break; + } + + /* get the remote user */ + retval = pam_get_ruser(pamh, &ruser, NULL); + (void) pam_set_item(pamh, PAM_RUSER, ruser); + if (retval != PAM_SUCCESS) { + if (opts.opt_debug) + _pam_log(LOG_DEBUG, "could not get the remote username"); + break; + } + + /* get the local user */ + retval = pam_get_user(pamh, &luser, NULL); + + if (retval != PAM_SUCCESS) { + if (opts.opt_debug) + _pam_log(LOG_DEBUG, "could not determine name of local user"); + break; + } + + if (opts.superuser && !strcmp(opts.superuser, luser)) { + as_root = 1; + } + + /* check if the luser uid == 0... --cristiang */ + if (! opts.opt_no_uid_check) { + struct passwd *luser_pwd; + + luser_pwd = getpwnam(luser); + if (luser_pwd == NULL) { + if (opts.opt_debug) + _pam_log(LOG_DEBUG, "user '%s' unknown to this system", + luser); + retval = PAM_AUTH_ERR; + break; + } + if (luser_pwd->pw_uid == 0) + as_root = 1; + luser_pwd = NULL; /* forget */ + } +/* + * Validate the account information. + */ + if (pam_ruserok (pamh, &opts, rhost, as_root, ruser, luser) != 0) { + if ( !opts.opt_suppress ) { + _pam_log(LOG_WARNING, "denied to %s@%s as %s: %s", + ruser, rhost, luser, (opts.last_error==NULL) ? + "access not allowed":opts.last_error); + } + retval = PAM_AUTH_ERR; + } else { + _pam_log(LOG_NOTICE, "allowed to %s@%s as %s", + ruser, rhost, luser); + } + break; + } + + return retval; +} + +/* --- authentication management functions --- */ + +PAM_EXTERN +int pam_sm_authenticate (pam_handle_t *pamh, + int flags, + int argc, + const char **argv) +{ + int retval; + + if (sizeof(U32) != 4) { + _pam_log (LOG_ALERT, "pam_rhosts module can\'t work on this hardware " + "(yet)"); + return PAM_AUTH_ERR; + } + sethostent(1); + retval = _pam_auth_rhosts (pamh, flags, argc, argv); + endhostent(); + return retval; +} + +PAM_EXTERN +int pam_sm_setcred(pam_handle_t *pamh,int flags,int argc, + const char **argv) +{ + return PAM_SUCCESS; +} + +/* end of module definition */ + + +#ifdef PAM_STATIC + +/* static module data */ + +struct pam_module _pam_rhosts_auth_modstruct = { + "pam_rhosts_auth", + pam_sm_authenticate, + pam_sm_setcred, + NULL, + NULL, + NULL, + NULL, +}; + +#endif + +/* + * $Log$ + * Revision 1.1 2000/06/20 22:11:56 agmorgan + * Initial revision + * + * Revision 1.4 1999/11/08 05:46:58 morgan + * fixes for .71 + * + * Revision 1.3 1999/10/09 05:12:49 morgan + * added hosts_equiv_rootok support + * + * Revision 1.2 1998/12/14 05:47:58 morgan + * added a couple of options: specify the name of root, and don't do the + * user-known check. + * + * Revision 1.1.1.1 1998/07/12 05:17:16 morgan + * Linux PAM sources pre-0.66 + * + * Revision 1.12 1997/09/27 14:34:01 morgan + * fixed comment and renamed iruserok to pam_iruserok. + * + * Revision 1.11 1997/04/05 06:26:39 morgan + * fairly major fixes and enhancements (see CHANGELOG for 0.57 release) + * + * Revision 1.10 1997/02/09 02:09:30 morgan + * - implementation of 'debug' argument (Cristian Gafton) + * - we check for uid=0 accounts instead of hardcoded 'root' (Cristian Gafton) + * + * Revision 1.9 1996/12/01 03:09:47 morgan + * *** empty log message *** + * + * Revision 1.8 1996/11/12 06:08:59 morgan + * Oliver Crow's "rootok" patch plus a little clean up of set_option + * (AGM) + * + * Revision 1.7 1996/11/10 20:15:56 morgan + * cross platform support + * + * Revision 1.6 1996/08/09 05:46:29 morgan + * removed code for manually setting the remote username etc.. + * + */ |