src/journal-remote/microhttpd-util.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   This file is part of systemd.
   4
   5   Copyright 2012 Lennart Poettering
   6   Copyright 2012 Zbigniew Jędrzejewski-Szmek
   7 ***/
   8
   9 #include <stddef.h>
  10 #include <stdio.h>
  11 #include <string.h>
  12
  13 #if HAVE_GNUTLS
  14 #include <gnutls/gnutls.h>
  15 #include <gnutls/x509.h>
  16 #endif
  17
  18 #include "alloc-util.h"
  19 #include "log.h"
  20 #include "macro.h"
  21 #include "microhttpd-util.h"
  22 #include "string-util.h"
  23 #include "strv.h"
  24 #include "util.h"
  25
  26 void microhttpd_logger(void *arg, const char *fmt, va_list ap) {
  27         char *f;
  28
  29         f = strjoina("microhttpd: ", fmt);
  30
  31         DISABLE_WARNING_FORMAT_NONLITERAL;
  32         log_internalv(LOG_INFO, 0, NULL, 0, NULL, f, ap);
  33         REENABLE_WARNING;
  34 }
  35
  36 static int mhd_respond_internal(struct MHD_Connection *connection,
  37                                 enum MHD_RequestTerminationCode code,
  38                                 const char *buffer,
  39                                 size_t size,
  40                                 enum MHD_ResponseMemoryMode mode) {
  41         struct MHD_Response *response;
  42         int r;
  43
  44         assert(connection);
  45
  46         response = MHD_create_response_from_buffer(size, (char*) buffer, mode);
  47         if (!response)
  48                 return MHD_NO;
  49
  50         log_debug("Queueing response %u: %s", code, buffer);
  51         MHD_add_response_header(response, "Content-Type", "text/plain");
  52         r = MHD_queue_response(connection, code, response);
  53         MHD_destroy_response(response);
  54
  55         return r;
  56 }
  57
  58 int mhd_respond(struct MHD_Connection *connection,
  59                 enum MHD_RequestTerminationCode code,
  60                 const char *message) {
  61
  62         const char *fmt;
  63
  64         fmt = strjoina(message, "\n");
  65
  66         return mhd_respond_internal(connection, code,
  67                                     fmt, strlen(message) + 1,
  68                                     MHD_RESPMEM_PERSISTENT);
  69 }
  70
  71 int mhd_respond_oom(struct MHD_Connection *connection) {
  72         return mhd_respond(connection, MHD_HTTP_SERVICE_UNAVAILABLE,  "Out of memory.");
  73 }
  74
  75 int mhd_respondf(struct MHD_Connection *connection,
  76                  int error,
  77                  enum MHD_RequestTerminationCode code,
  78                  const char *format, ...) {
  79
  80         const char *fmt;
  81         char *m;
  82         int r;
  83         va_list ap;
  84
  85         assert(connection);
  86         assert(format);
  87
  88         if (error < 0)
  89                 error = -error;
  90         errno = -error;
  91         fmt = strjoina(format, "\n");
  92         va_start(ap, format);
  93 #pragma GCC diagnostic push
  94 #pragma GCC diagnostic ignored "-Wformat-nonliteral"
  95         r = vasprintf(&m, fmt, ap);
  96 #pragma GCC diagnostic pop
  97         va_end(ap);
  98
  99         if (r < 0)
 100                 return respond_oom(connection);
 101
 102         return mhd_respond_internal(connection, code, m, r, MHD_RESPMEM_MUST_FREE);
 103 }
 104
 105 #if HAVE_GNUTLS
 106
 107 static struct {
 108         const char *const names[4];
 109         int level;
 110         bool enabled;
 111 } gnutls_log_map[] = {
 112         { {"0"},                  LOG_DEBUG },
 113         { {"1", "audit"},         LOG_WARNING, true}, /* gnutls session audit */
 114         { {"2", "assert"},        LOG_DEBUG },        /* gnutls assert log */
 115         { {"3", "hsk", "ext"},    LOG_DEBUG },        /* gnutls handshake log */
 116         { {"4", "rec"},           LOG_DEBUG },        /* gnutls record log */
 117         { {"5", "dtls"},          LOG_DEBUG },        /* gnutls DTLS log */
 118         { {"6", "buf"},           LOG_DEBUG },
 119         { {"7", "write", "read"}, LOG_DEBUG },
 120         { {"8"},                  LOG_DEBUG },
 121         { {"9", "enc", "int"},    LOG_DEBUG },
 122 };
 123
 124 static void log_func_gnutls(int level, const char *message) {
 125         assert_se(message);
 126
 127         if (0 <= level && level < (int) ELEMENTSOF(gnutls_log_map)) {
 128                 if (gnutls_log_map[level].enabled)
 129                         log_internal(gnutls_log_map[level].level, 0, NULL, 0, NULL, "gnutls %d/%s: %s", level, gnutls_log_map[level].names[1], message);
 130         } else {
 131                 log_debug("Received GNUTLS message with unknown level %d.", level);
 132                 log_internal(LOG_DEBUG, 0, NULL, 0, NULL, "gnutls: %s", message);
 133         }
 134 }
 135
 136 static void log_reset_gnutls_level(void) {
 137         int i;
 138
 139         for (i = ELEMENTSOF(gnutls_log_map) - 1; i >= 0; i--)
 140                 if (gnutls_log_map[i].enabled) {
 141                         log_debug("Setting gnutls log level to %d", i);
 142                         gnutls_global_set_log_level(i);
 143                         break;
 144                 }
 145 }
 146
 147 static int log_enable_gnutls_category(const char *cat) {
 148         unsigned i;
 149
 150         if (streq(cat, "all")) {
 151                 for (i = 0; i < ELEMENTSOF(gnutls_log_map); i++)
 152                         gnutls_log_map[i].enabled = true;
 153                 log_reset_gnutls_level();
 154                 return 0;
 155         } else
 156                 for (i = 0; i < ELEMENTSOF(gnutls_log_map); i++)
 157                         if (strv_contains((char**)gnutls_log_map[i].names, cat)) {
 158                                 gnutls_log_map[i].enabled = true;
 159                                 log_reset_gnutls_level();
 160                                 return 0;
 161                         }
 162         log_error("No such log category: %s", cat);
 163         return -EINVAL;
 164 }
 165
 166 int setup_gnutls_logger(char **categories) {
 167         char **cat;
 168         int r;
 169
 170         gnutls_global_set_log_function(log_func_gnutls);
 171
 172         if (categories) {
 173                 STRV_FOREACH(cat, categories) {
 174                         r = log_enable_gnutls_category(*cat);
 175                         if (r < 0)
 176                                 return r;
 177                 }
 178         } else
 179                 log_reset_gnutls_level();
 180
 181         return 0;
 182 }
 183
 184 static int verify_cert_authorized(gnutls_session_t session) {
 185         unsigned status;
 186         gnutls_certificate_type_t type;
 187         gnutls_datum_t out;
 188         int r;
 189
 190         r = gnutls_certificate_verify_peers2(session, &status);
 191         if (r < 0)
 192                 return log_error_errno(r, "gnutls_certificate_verify_peers2 failed: %m");
 193
 194         type = gnutls_certificate_type_get(session);
 195         r = gnutls_certificate_verification_status_print(status, type, &out, 0);
 196         if (r < 0)
 197                 return log_error_errno(r, "gnutls_certificate_verification_status_print failed: %m");
 198
 199         log_debug("Certificate status: %s", out.data);
 200         gnutls_free(out.data);
 201
 202         return status == 0 ? 0 : -EPERM;
 203 }
 204
 205 static int get_client_cert(gnutls_session_t session, gnutls_x509_crt_t *client_cert) {
 206         const gnutls_datum_t *pcert;
 207         unsigned listsize;
 208         gnutls_x509_crt_t cert;
 209         int r;
 210
 211         assert(session);
 212         assert(client_cert);
 213
 214         pcert = gnutls_certificate_get_peers(session, &listsize);
 215         if (!pcert || !listsize) {
 216                 log_error("Failed to retrieve certificate chain");
 217                 return -EINVAL;
 218         }
 219
 220         r = gnutls_x509_crt_init(&cert);
 221         if (r < 0) {
 222                 log_error("Failed to initialize client certificate");
 223                 return r;
 224         }
 225
 226         /* Note that by passing values between 0 and listsize here, you
 227            can get access to the CA's certs */
 228         r = gnutls_x509_crt_import(cert, &pcert[0], GNUTLS_X509_FMT_DER);
 229         if (r < 0) {
 230                 log_error("Failed to import client certificate");
 231                 gnutls_x509_crt_deinit(cert);
 232                 return r;
 233         }
 234
 235         *client_cert = cert;
 236         return 0;
 237 }
 238
 239 static int get_auth_dn(gnutls_x509_crt_t client_cert, char **buf) {
 240         size_t len = 0;
 241         int r;
 242
 243         assert(buf);
 244         assert(*buf == NULL);
 245
 246         r = gnutls_x509_crt_get_dn(client_cert, NULL, &len);
 247         if (r != GNUTLS_E_SHORT_MEMORY_BUFFER) {
 248                 log_error("gnutls_x509_crt_get_dn failed");
 249                 return r;
 250         }
 251
 252         *buf = malloc(len);
 253         if (!*buf)
 254                 return log_oom();
 255
 256         gnutls_x509_crt_get_dn(client_cert, *buf, &len);
 257         return 0;
 258 }
 259
 260 static inline void gnutls_x509_crt_deinitp(gnutls_x509_crt_t *p) {
 261         gnutls_x509_crt_deinit(*p);
 262 }
 263
 264 int check_permissions(struct MHD_Connection *connection, int *code, char **hostname) {
 265         const union MHD_ConnectionInfo *ci;
 266         gnutls_session_t session;
 267         _cleanup_(gnutls_x509_crt_deinitp) gnutls_x509_crt_t client_cert = NULL;
 268         _cleanup_free_ char *buf = NULL;
 269         int r;
 270
 271         assert(connection);
 272         assert(code);
 273
 274         *code = 0;
 275
 276         ci = MHD_get_connection_info(connection,
 277                                      MHD_CONNECTION_INFO_GNUTLS_SESSION);
 278         if (!ci) {
 279                 log_error("MHD_get_connection_info failed: session is unencrypted");
 280                 *code = mhd_respond(connection, MHD_HTTP_FORBIDDEN,
 281                                     "Encrypted connection is required");
 282                 return -EPERM;
 283         }
 284         session = ci->tls_session;
 285         assert(session);
 286
 287         r = get_client_cert(session, &client_cert);
 288         if (r < 0) {
 289                 *code = mhd_respond(connection, MHD_HTTP_UNAUTHORIZED,
 290                                     "Authorization through certificate is required");
 291                 return -EPERM;
 292         }
 293
 294         r = get_auth_dn(client_cert, &buf);
 295         if (r < 0) {
 296                 *code = mhd_respond(connection, MHD_HTTP_UNAUTHORIZED,
 297                                     "Failed to determine distinguished name from certificate");
 298                 return -EPERM;
 299         }
 300
 301         log_debug("Connection from %s", buf);
 302
 303         if (hostname)
 304                 *hostname = TAKE_PTR(buf);
 305
 306         r = verify_cert_authorized(session);
 307         if (r < 0) {
 308                 log_warning("Client is not authorized");
 309                 *code = mhd_respond(connection, MHD_HTTP_UNAUTHORIZED,
 310                                     "Client certificate not signed by recognized authority");
 311         }
 312         return r;
 313 }
 314
 315 #else
 316 int check_permissions(struct MHD_Connection *connection, int *code, char **hostname) {
 317         return -EPERM;
 318 }
 319
 320 int setup_gnutls_logger(char **categories) {
 321         if (categories)
 322                 log_notice("Ignoring specified gnutls logging categories — gnutls not available.");
 323         return 0;
 324 }
 325 #endif