1 /* 2 * mod_authn_pam - PAM backend for lighttpd HTTP auth 3 * 4 * Copyright(c) 2018 Glenn Strauss gstrauss()gluelogic.com All rights reserved 5 * License: BSD 3-clause (same as lighttpd) 6 */ 7 #include "first.h" 8 9 /* mod_authn_pam 10 * 11 * FUTURE POTENTIAL PERFORMANCE ENHANCEMENTS: 12 * - database response is not cached 13 * TODO: db response caching (for limited time) to reduce load on db 14 * (only cache successful logins to prevent cache bloat?) 15 * (or limit number of entries (size) of cache) 16 * (maybe have negative cache (limited size) of names not found in database) 17 * - database query is synchronous and blocks waiting for response 18 */ 19 20 #include <security/pam_appl.h> 21 22 #include "base.h" 23 #include "http_auth.h" 24 #include "log.h" 25 #include "plugin.h" 26 27 #include <stdlib.h> 28 #include <string.h> 29 30 typedef struct { 31 const char *service; 32 } plugin_config; 33 34 typedef struct { 35 PLUGIN_DATA; 36 plugin_config defaults; 37 plugin_config conf; 38 } plugin_data; 39 40 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); 41 42 INIT_FUNC(mod_authn_pam_init) { 43 static http_auth_backend_t http_auth_backend_pam = 44 { "pam", mod_authn_pam_basic, NULL, NULL }; 45 plugin_data *p = calloc(1, sizeof(*p)); 46 47 /* register http_auth_backend_pam */ 48 http_auth_backend_pam.p_d = p; 49 http_auth_backend_set(&http_auth_backend_pam); 50 51 return p; 52 } 53 54 static void mod_authn_pam_merge_config_cpv(plugin_config * const pconf, const config_plugin_value_t * const cpv) { 55 switch (cpv->k_id) { /* index into static config_plugin_keys_t cpk[] */ 56 case 0: /* auth.backend.pam.opts */ 57 if (cpv->vtype == T_CONFIG_LOCAL) 58 pconf->service = cpv->v.v; 59 break; 60 default:/* should not happen */ 61 return; 62 } 63 } 64 65 static void mod_authn_pam_merge_config(plugin_config * const pconf, const config_plugin_value_t *cpv) { 66 do { 67 mod_authn_pam_merge_config_cpv(pconf, cpv); 68 } while ((++cpv)->k_id != -1); 69 } 70 71 static void mod_authn_pam_patch_config(request_st * const r, plugin_data * const p) { 72 p->conf = p->defaults; /* copy small struct instead of memcpy() */ 73 /*memcpy(&p->conf, &p->defaults, sizeof(plugin_config));*/ 74 for (int i = 1, used = p->nconfig; i < used; ++i) { 75 if (config_check_cond(r, (uint32_t)p->cvlist[i].k_id)) 76 mod_authn_pam_merge_config(&p->conf, 77 p->cvlist + p->cvlist[i].v.u2[0]); 78 } 79 } 80 81 SETDEFAULTS_FUNC(mod_authn_pam_set_defaults) { 82 static const config_plugin_keys_t cpk[] = { 83 { CONST_STR_LEN("auth.backend.pam.opts"), 84 T_CONFIG_ARRAY_KVSTRING, 85 T_CONFIG_SCOPE_CONNECTION } 86 ,{ NULL, 0, 87 T_CONFIG_UNSET, 88 T_CONFIG_SCOPE_UNSET } 89 }; 90 91 plugin_data * const p = p_d; 92 if (!config_plugin_values_init(srv, p, cpk, "mod_authn_pam")) 93 return HANDLER_ERROR; 94 95 /* process and validate config directives 96 * (init i to 0 if global context; to 1 to skip empty global context) */ 97 for (int i = !p->cvlist[0].v.u2[1]; i < p->nconfig; ++i) { 98 config_plugin_value_t *cpv = p->cvlist + p->cvlist[i].v.u2[0]; 99 for (; -1 != cpv->k_id; ++cpv) { 100 switch (cpv->k_id) { 101 case 0: /* auth.backend.pam.opts */ 102 if (cpv->v.a->used) { 103 const data_string *ds = (const data_string *) 104 array_get_element_klen(cpv->v.a,CONST_STR_LEN("service")); 105 cpv->v.v = (NULL != ds) ? ds->value.ptr : "http"; 106 cpv->vtype = T_CONFIG_LOCAL; 107 } 108 break; 109 default:/* should not happen */ 110 break; 111 } 112 } 113 } 114 115 p->defaults.service = "http"; 116 117 /* initialize p->defaults from global config context */ 118 if (p->nconfig > 0 && p->cvlist->v.u2[1]) { 119 const config_plugin_value_t *cpv = p->cvlist + p->cvlist->v.u2[0]; 120 if (-1 != cpv->k_id) 121 mod_authn_pam_merge_config(&p->defaults, cpv); 122 } 123 124 return HANDLER_GO_ON; 125 } 126 127 static int mod_authn_pam_fn_conv(int num_msg, const struct pam_message **msg, struct pam_response **resp, void *appdata_ptr) { 128 const char * const pw = (char *)appdata_ptr; 129 struct pam_response * const pr = *resp = 130 (struct pam_response *)malloc(num_msg * sizeof(struct pam_response)); 131 for (int i = 0; i < num_msg; ++i) { 132 const int style = msg[i]->msg_style; 133 pr[i].resp_retcode = 0; 134 pr[i].resp = (style==PAM_PROMPT_ECHO_OFF || style==PAM_PROMPT_ECHO_ON) 135 ? strdup(pw) 136 : NULL; 137 } 138 return PAM_SUCCESS; 139 } 140 141 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) { 142 plugin_data *p = (plugin_data *)p_d; 143 pam_handle_t *pamh = NULL; 144 struct pam_conv conv = { mod_authn_pam_fn_conv, NULL }; 145 const int flags = PAM_SILENT | PAM_DISALLOW_NULL_AUTHTOK; 146 int rc; 147 UNUSED(realm); 148 *(const char **)&conv.appdata_ptr = pw; /*(cast away const)*/ 149 150 mod_authn_pam_patch_config(r, p); 151 152 const char * const addrstr = r->con->dst_addr_buf->ptr; 153 rc = pam_start(p->conf.service, username->ptr, &conv, &pamh); 154 if (PAM_SUCCESS != rc 155 || PAM_SUCCESS !=(rc = pam_set_item(pamh, PAM_RHOST, addrstr)) 156 || PAM_SUCCESS !=(rc = pam_authenticate(pamh, flags)) 157 || PAM_SUCCESS !=(rc = pam_acct_mgmt(pamh, flags))) 158 log_error(r->conf.errh, __FILE__, __LINE__, 159 "pam: %s", pam_strerror(pamh, rc)); 160 pam_end(pamh, rc); 161 return (PAM_SUCCESS == rc) ? HANDLER_GO_ON : HANDLER_ERROR; 162 } 163 164 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) { 165 char *realm = require->realm->ptr; 166 handler_t rc = mod_authn_pam_query(r, p_d, username, realm, pw); 167 if (HANDLER_GO_ON != rc) return rc; 168 return http_auth_match_rules(require, username->ptr, NULL, NULL) 169 ? HANDLER_GO_ON /* access granted */ 170 : HANDLER_ERROR; 171 } 172 173 int mod_authn_pam_plugin_init(plugin *p); 174 int mod_authn_pam_plugin_init(plugin *p) { 175 p->version = LIGHTTPD_VERSION_ID; 176 p->name = "authn_pam"; 177 p->init = mod_authn_pam_init; 178 p->set_defaults= mod_authn_pam_set_defaults; 179 180 return 0; 181 } 182