mod_auth.c

/* ====================================================================
 * The Apache Software License, Version 1.1
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 *
 * Portions of this software are based upon public domain software
 * originally written at the National Center for Supercomputing Applications,
 * University of Illinois, Urbana-Champaign.
 */

/*
 * http_auth: authentication
 * 
 * Rob McCool
 * 
 * Adapted to Apache by rst.
 *
 * dirkx - Added Authoritative control to allow passing on to lower
 *         modules if and only if the userid is not known to this
 *         module. A known user with a faulty or absent password still
 *         causes an AuthRequired. The default is 'Authoritative', i.e.
 *         no control is passed along.
 */

#include "ap_config.h"
#include "apr_strings.h"
#include "apr_md5.h"
#include "httpd.h"
#include "http_config.h"
#include "http_core.h"
#include "http_log.h"
#include "http_protocol.h"
#include "http_request.h"

typedef struct auth_config_struct {
    char *auth_pwfile;
    char *auth_grpfile;
    int auth_authoritative;
} auth_config_rec;

static void *create_auth_dir_config(apr_pool_t *p, char *d)
{
    auth_config_rec *sec =
    (auth_config_rec *) apr_pcalloc(p, sizeof(auth_config_rec));
    sec->auth_pwfile = NULL;	/* just to illustrate the default really */
    sec->auth_grpfile = NULL;	/* unless you have a broken HP cc */
    sec->auth_authoritative = 1;	/* keep the fortress secure by default */
    return sec;
}

static const char *set_auth_slot(cmd_parms *cmd, void *offset, const char *f, 
                                 const char *t)
{
    if (t && strcmp(t, "standard"))
	return apr_pstrcat(cmd->pool, "Invalid auth file type: ", t, NULL);

    return ap_set_file_slot(cmd, offset, f);
}

static const command_rec auth_cmds[] =
{
    AP_INIT_TAKE12("AuthUserFile", set_auth_slot,
                   (void *) XtOffsetOf(auth_config_rec, auth_pwfile), OR_AUTHCFG,
                   "text file containing user IDs and passwords"),
    AP_INIT_TAKE12("AuthGroupFile", set_auth_slot,
                   (void *) XtOffsetOf(auth_config_rec, auth_grpfile), OR_AUTHCFG,
                   "text file containing group names and member user IDs"),
    AP_INIT_FLAG("AuthAuthoritative", ap_set_flag_slot,
                 (void *) XtOffsetOf(auth_config_rec, auth_authoritative),
                 OR_AUTHCFG,
                 "Set to 'no' to allow access control to be passed along to lower "
                 "modules if the UserID is not known to this module"),
    {NULL}
};

module AP_MODULE_DECLARE_DATA auth_module;

static char *get_pw(request_rec *r, char *user, char *auth_pwfile)
{
    configfile_t *f;
    char l[MAX_STRING_LEN];
    const char *rpw, *w;
    apr_status_t status;

    if ((status = ap_pcfg_openfile(&f, r->pool, auth_pwfile)) != APR_SUCCESS) {
	ap_log_rerror(APLOG_MARK, APLOG_ERR, status, r,
		    "Could not open password file: %s", auth_pwfile);
	return NULL;
    }
    while (!(ap_cfg_getline(l, MAX_STRING_LEN, f))) {
	if ((l[0] == '#') || (!l[0]))
	    continue;
	rpw = l;
	w = ap_getword(r->pool, &rpw, ':');

	if (!strcmp(user, w)) {
	    ap_cfg_closefile(f);
	    return ap_getword(r->pool, &rpw, ':');
	}
    }
    ap_cfg_closefile(f);
    return NULL;
}

static apr_table_t *groups_for_user(apr_pool_t *p, char *user, char *grpfile)
{
    configfile_t *f;
    apr_table_t *grps = apr_make_table(p, 15);
    apr_pool_t *sp;
    char l[MAX_STRING_LEN];
    const char *group_name, *ll, *w;
    apr_status_t status;

    if ((status = ap_pcfg_openfile(&f, p, grpfile)) != APR_SUCCESS) {
/*add?	aplog_error(APLOG_MARK, APLOG_ERR, NULL,
		    "Could not open group file: %s", grpfile);*/
	return NULL;
    }

    apr_create_pool(&sp, p);

    while (!(ap_cfg_getline(l, MAX_STRING_LEN, f))) {
	if ((l[0] == '#') || (!l[0]))
	    continue;
	ll = l;
	apr_clear_pool(sp);

	group_name = ap_getword(sp, &ll, ':');

	while (ll[0]) {
	    w = ap_getword_conf(sp, &ll);
	    if (!strcmp(w, user)) {
		apr_table_setn(grps, apr_pstrdup(p, group_name), "in");
		break;
	    }
	}
    }
    ap_cfg_closefile(f);
    apr_destroy_pool(sp);
    return grps;
}

/* These functions return 0 if client is OK, and proper error status
 * if not... either HTTP_UNAUTHORIZED, if we made a check, and it failed, or
 * HTTP_INTERNAL_SERVER_ERROR, if things are so totally confused that we
 * couldn't figure out how to tell if the client is authorized or not.
 *
 * If they return DECLINED, and all other modules also decline, that's
 * treated by the server core as a configuration error, logged and
 * reported as such.
 */

/* Determine user ID, and check if it really is that user, for HTTP
 * basic authentication...
 */

static int authenticate_basic_user(request_rec *r)
{
    auth_config_rec *sec =
    (auth_config_rec *) ap_get_module_config(r->per_dir_config, &auth_module);
    const char *sent_pw;
    char *real_pw;
    apr_status_t invalid_pw;
    int res;

    if ((res = ap_get_basic_auth_pw(r, &sent_pw)))
	return res;

    if (!sec->auth_pwfile)
	return DECLINED;

    if (!(real_pw = get_pw(r, r->user, sec->auth_pwfile))) {
	if (!(sec->auth_authoritative))
	    return DECLINED;
	ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_ERR, 0, r,
		    "user %s not found: %s", r->user, r->uri);
	ap_note_basic_auth_failure(r);
	return HTTP_UNAUTHORIZED;
    }
    invalid_pw = apr_validate_password(sent_pw, real_pw);
    if (invalid_pw != APR_SUCCESS) {
	ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_ERR, 0, r,
		      "user %s: authentication failure for \"%s\": "
                      "Password Mismatch",
		      r->user, r->uri);
	ap_note_basic_auth_failure(r);
	return HTTP_UNAUTHORIZED;
    }
    return OK;
}

/* Checking ID */

static int check_user_access(request_rec *r)
{
    auth_config_rec *sec =
    (auth_config_rec *) ap_get_module_config(r->per_dir_config, &auth_module);
    char *user = r->user;
    int m = r->method_number;
    int method_restricted = 0;
    register int x;
    const char *t, *w;
    apr_table_t *grpstatus;
    const apr_array_header_t *reqs_arr = ap_requires(r);
    require_line *reqs;

    /* BUG FIX: tadc, 11-Nov-1995.  If there is no "requires" directive, 
     * then any user will do.
     */
    if (!reqs_arr)
	return (OK);
    reqs = (require_line *) reqs_arr->elts;

    if (sec->auth_grpfile)
	grpstatus = groups_for_user(r->pool, user, sec->auth_grpfile);
    else
	grpstatus = NULL;

    for (x = 0; x < reqs_arr->nelts; x++) {

	if (!(reqs[x].method_mask & (1 << m)))
	    continue;

	method_restricted = 1;

	t = reqs[x].requirement;
	w = ap_getword_white(r->pool, &t);
	if (!strcmp(w, "valid-user"))
	    return OK;
	if (!strcmp(w, "user")) {
	    while (t[0]) {
		w = ap_getword_conf(r->pool, &t);
		if (!strcmp(user, w))
		    return OK;
	    }
	}
	else if (!strcmp(w, "group")) {
	    if (!grpstatus)
		return DECLINED;	/* DBM group?  Something else? */

	    while (t[0]) {
		w = ap_getword_conf(r->pool, &t);
		if (apr_table_get(grpstatus, w))
		    return OK;
	    }
	} else if (sec->auth_authoritative) {
	    /* if we aren't authoritative, any require directive could be
	     * valid even if we don't grok it.  However, if we are 
	     * authoritative, we can warn the user they did something wrong.
	     * That something could be a missing "AuthAuthoritative off", but
	     * more likely is a typo in the require directive.
	     */
	    ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_ERR, 0, r,
		"access to %s failed, reason: unknown require directive:"
		"\"%s\"", r->uri, reqs[x].requirement);
	}
    }

    if (!method_restricted)
	return OK;

    if (!(sec->auth_authoritative))
	return DECLINED;

    ap_log_rerror(APLOG_MARK, APLOG_NOERRNO|APLOG_ERR, 0, r,
	"access to %s failed, reason: user %s not allowed access",
	r->uri, user);
	
    ap_note_basic_auth_failure(r);
    return HTTP_UNAUTHORIZED;
}

static void register_hooks(void)
{
    ap_hook_check_user_id(authenticate_basic_user,NULL,NULL,AP_HOOK_MIDDLE);
    ap_hook_auth_checker(check_user_access,NULL,NULL,AP_HOOK_MIDDLE);
}

module AP_MODULE_DECLARE_DATA auth_module =
{
    STANDARD20_MODULE_STUFF,
    create_auth_dir_config,	/* dir config creater */
    NULL,			/* dir merger --- default is to override */
    NULL,			/* server config */
    NULL,			/* merge server config */
    auth_cmds,			/* command apr_table_t */
    NULL,			/* handlers */
    register_hooks		/* register hooks */
};