src/journal-remote/microhttpd-util.c

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