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/*
* mod_authn_pam - PAM backend for lighttpd HTTP auth
*
* Copyright(c) 2018 Glenn Strauss gstrauss()gluelogic.com All rights reserved
* License: BSD 3-clause (same as lighttpd)
*/
#include "first.h"
/* mod_authn_pam
*
* FUTURE POTENTIAL PERFORMANCE ENHANCEMENTS:
* - database response is not cached
* TODO: db response caching (for limited time) to reduce load on db
* (only cache successful logins to prevent cache bloat?)
* (or limit number of entries (size) of cache)
* (maybe have negative cache (limited size) of names not found in database)
* - database query is synchronous and blocks waiting for response
*/
#include <stdlib.h>
#include <string.h>
#include <security/pam_appl.h>
#include "mod_auth_api.h"
#include "base.h"
#include "log.h"
#include "plugin.h"
typedef struct {
const char *service;
} plugin_config;
typedef struct {
PLUGIN_DATA;
plugin_config defaults;
plugin_config conf;
} plugin_data;
static handler_t mod_authn_pam_basic(request_st *r, void *p_d, const http_auth_require_t *require, const buffer *username, const char *pw);
INIT_FUNC(mod_authn_pam_init) {
static http_auth_backend_t http_auth_backend_pam =
{ "pam", mod_authn_pam_basic, NULL, NULL };
plugin_data *p = ck_calloc(1, sizeof(*p));
/* register http_auth_backend_pam */
http_auth_backend_pam.p_d = p;
http_auth_backend_set(&http_auth_backend_pam);
return p;
}
static void mod_authn_pam_merge_config_cpv(plugin_config * const pconf, const config_plugin_value_t * const cpv) {
switch (cpv->k_id) { /* index into static config_plugin_keys_t cpk[] */
case 0: /* auth.backend.pam.opts */
if (cpv->vtype == T_CONFIG_LOCAL)
pconf->service = cpv->v.v;
break;
default:/* should not happen */
return;
}
}
static void mod_authn_pam_merge_config(plugin_config * const pconf, const config_plugin_value_t *cpv) {
do {
mod_authn_pam_merge_config_cpv(pconf, cpv);
} while ((++cpv)->k_id != -1);
}
static void mod_authn_pam_patch_config(request_st * const r, plugin_data * const p) {
p->conf = p->defaults; /* copy small struct instead of memcpy() */
/*memcpy(&p->conf, &p->defaults, sizeof(plugin_config));*/
for (int i = 1, used = p->nconfig; i < used; ++i) {
if (config_check_cond(r, (uint32_t)p->cvlist[i].k_id))
mod_authn_pam_merge_config(&p->conf,
p->cvlist + p->cvlist[i].v.u2[0]);
}
}
SETDEFAULTS_FUNC(mod_authn_pam_set_defaults) {
static const config_plugin_keys_t cpk[] = {
{ CONST_STR_LEN("auth.backend.pam.opts"),
T_CONFIG_ARRAY_KVSTRING,
T_CONFIG_SCOPE_CONNECTION }
,{ NULL, 0,
T_CONFIG_UNSET,
T_CONFIG_SCOPE_UNSET }
};
plugin_data * const p = p_d;
if (!config_plugin_values_init(srv, p, cpk, "mod_authn_pam"))
return HANDLER_ERROR;
/* process and validate config directives
* (init i to 0 if global context; to 1 to skip empty global context) */
for (int i = !p->cvlist[0].v.u2[1]; i < p->nconfig; ++i) {
config_plugin_value_t *cpv = p->cvlist + p->cvlist[i].v.u2[0];
for (; -1 != cpv->k_id; ++cpv) {
switch (cpv->k_id) {
case 0: /* auth.backend.pam.opts */
if (cpv->v.a->used) {
const data_string *ds = (const data_string *)
array_get_element_klen(cpv->v.a,CONST_STR_LEN("service"));
*(const void **)&cpv->v.v =
(NULL != ds) ? ds->value.ptr : "http";
cpv->vtype = T_CONFIG_LOCAL;
}
break;
default:/* should not happen */
break;
}
}
}
p->defaults.service = "http";
/* initialize p->defaults from global config context */
if (p->nconfig > 0 && p->cvlist->v.u2[1]) {
const config_plugin_value_t *cpv = p->cvlist + p->cvlist->v.u2[0];
if (-1 != cpv->k_id)
mod_authn_pam_merge_config(&p->defaults, cpv);
}
return HANDLER_GO_ON;
}
static int mod_authn_pam_fn_conv(int num_msg, const struct pam_message **msg, struct pam_response **resp, void *appdata_ptr) {
const char * const pw = (char *)appdata_ptr;
struct pam_response * const pr = *resp =
(struct pam_response *)ck_malloc(num_msg * sizeof(struct pam_response));
for (int i = 0; i < num_msg; ++i) {
const int style = msg[i]->msg_style;
pr[i].resp_retcode = 0;
pr[i].resp = (style==PAM_PROMPT_ECHO_OFF || style==PAM_PROMPT_ECHO_ON)
? strdup(pw)
: NULL;
}
return PAM_SUCCESS;
}
static handler_t mod_authn_pam_query(request_st * const r, void *p_d, const buffer * const username, const char * const realm, const char * const pw) {
plugin_data *p = (plugin_data *)p_d;
pam_handle_t *pamh = NULL;
struct pam_conv conv = { mod_authn_pam_fn_conv, NULL };
const int flags = PAM_SILENT | PAM_DISALLOW_NULL_AUTHTOK;
int rc;
UNUSED(realm);
*(const char **)&conv.appdata_ptr = pw; /*(cast away const)*/
mod_authn_pam_patch_config(r, p);
const char * const addrstr = r->dst_addr_buf->ptr;
rc = pam_start(p->conf.service, username->ptr, &conv, &pamh);
if (PAM_SUCCESS != rc
|| PAM_SUCCESS !=(rc = pam_set_item(pamh, PAM_RHOST, addrstr))
|| PAM_SUCCESS !=(rc = pam_authenticate(pamh, flags))
|| PAM_SUCCESS !=(rc = pam_acct_mgmt(pamh, flags)))
log_error(r->conf.errh, __FILE__, __LINE__,
"pam: %s", pam_strerror(pamh, rc));
pam_end(pamh, rc);
return (PAM_SUCCESS == rc) ? HANDLER_GO_ON : HANDLER_ERROR;
}
static handler_t mod_authn_pam_basic(request_st * const r, void *p_d, const http_auth_require_t * const require, const buffer * const username, const char * const pw) {
char *realm = require->realm->ptr;
handler_t rc = mod_authn_pam_query(r, p_d, username, realm, pw);
if (HANDLER_GO_ON != rc) return rc;
return http_auth_match_rules(require, username->ptr, NULL, NULL)
? HANDLER_GO_ON /* access granted */
: HANDLER_ERROR;
}
__attribute_cold__
__declspec_dllexport__
int mod_authn_pam_plugin_init(plugin *p);
int mod_authn_pam_plugin_init(plugin *p) {
p->version = LIGHTTPD_VERSION_ID;
p->name = "authn_pam";
p->init = mod_authn_pam_init;
p->set_defaults= mod_authn_pam_set_defaults;
return 0;
}
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