usign-exec.c

   1 /*
   2  * wrapper functions around the usign executable
   3  * Copyright (C) 2018 Daniel Golle <daniel@makrotopia.org>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 3
   7  * as published by the Free Software Foundation
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  */
  14
  15 #include <stdbool.h>
  16 #include <stdio.h>
  17 #include <string.h>
  18 #include <unistd.h>
  19 #include <sys/wait.h>
  20
  21 #include "usign.h"
  22
  23 #ifdef UCERT_HOST_BUILD
  24 #define USIGN_EXEC "usign"
  25 #else
  26 #define USIGN_EXEC "/usr/bin/usign"
  27 #endif
  28
  29 /*
  30  * check for revoker deadlink in pubkeydir
  31  * return true if a revoker exists, false otherwise
  32  */
  33 int _usign_key_is_revoked(const char *fingerprint, const char *pubkeydir) {
  34         char tml[64] = {0};
  35         char rfname[256] = {0};
  36
  37         snprintf(rfname, sizeof(rfname)-1, "%s/%s", pubkeydir, fingerprint);
  38         if (readlink(rfname, tml, sizeof(tml)) > 0 &&
  39             !strcmp(tml, ".revoked.")) {
  40                 return true;
  41         };
  42
  43         return false;
  44 }
  45
  46 #ifdef UCERT_FULL
  47 /*
  48  * call usign -S ...
  49  * return WEXITSTATUS or -1 if fork or execv fails
  50  */
  51 int usign_s(const char *msgfile, const char *seckeyfile, const char *sigfile, bool quiet) {
  52         pid_t pid;
  53         int status;
  54         const char *usign_argv[16] = {0};
  55         unsigned int usign_argc = 0;
  56
  57         usign_argv[usign_argc++] = USIGN_EXEC;
  58         usign_argv[usign_argc++] = "-S";
  59         usign_argv[usign_argc++] = "-m";
  60         usign_argv[usign_argc++] = msgfile;
  61         usign_argv[usign_argc++] = "-s";
  62         usign_argv[usign_argc++] = seckeyfile;
  63         usign_argv[usign_argc++] = "-x";
  64         usign_argv[usign_argc++] = sigfile;
  65
  66         if (quiet)
  67                 usign_argv[usign_argc++] = "-q";
  68
  69         pid = fork();
  70         switch (pid) {
  71         case -1:
  72                 return -1;
  73
  74         case 0:
  75                 if (execvp(usign_argv[0], (char *const *)usign_argv))
  76                         return -1;
  77
  78                 break;
  79
  80         default:
  81                 waitpid(pid, &status, 0);
  82                 return WEXITSTATUS(status);
  83         }
  84
  85         return -1;
  86 }
  87 #else
  88 int usign_s(const char *msgfile, const char *seckeyfile, const char *sigfile, bool quiet) {
  89         return -1;
  90 };
  91 #endif
  92
  93 /*
  94  * call usign -F ... and set fingerprint returned
  95  * return WEXITSTATUS or -1 if fork or execv fails
  96  */
  97 static int usign_f(char *fingerprint, const char *pubkeyfile, const char *seckeyfile, const char *sigfile) {
  98         int fds[2];
  99         pid_t pid;
 100         int status;
 101         const char *usign_argv[16] = {0};
 102         unsigned int usign_argc = 0;
 103
 104         if (pipe(fds))
 105                 return -1;
 106
 107         usign_argv[usign_argc++] = USIGN_EXEC;
 108         usign_argv[usign_argc++] = "-F";
 109
 110         if (pubkeyfile) {
 111                 usign_argv[usign_argc++] = "-p";
 112                 usign_argv[usign_argc++] = pubkeyfile;
 113         }
 114
 115         if (seckeyfile) {
 116                 usign_argv[usign_argc++] = "-s";
 117                 usign_argv[usign_argc++] = seckeyfile;
 118         }
 119
 120         if (sigfile) {
 121                 usign_argv[usign_argc++] = "-x";
 122                 usign_argv[usign_argc++] = sigfile;
 123         }
 124
 125         pid = fork();
 126         switch (pid) {
 127         case -1:
 128                 return -1;
 129
 130         case 0:
 131                 dup2(fds[1], 1);
 132
 133                 close(0);
 134                 close(2);
 135                 close(fds[0]);
 136                 close(fds[1]);
 137
 138                 if (execvp(usign_argv[0], (char *const *)usign_argv))
 139                         return -1;
 140
 141                 break;
 142
 143         default:
 144                 waitpid(pid, &status, 0);
 145                 status = WEXITSTATUS(status);
 146                 if (fingerprint && !WEXITSTATUS(status)) {
 147                         ssize_t r;
 148                         memset(fingerprint, 0, 17);
 149                         r = read(fds[0], fingerprint, 17);
 150                         if (r < 16)
 151                                 status = -1;
 152
 153                         fingerprint[16] = '\0';
 154
 155                 }
 156                 close(fds[0]);
 157                 close(fds[1]);
 158                 return status;
 159         }
 160
 161         return -1;
 162 }
 163
 164 /*
 165  * call usign -F -p ...
 166  */
 167 int usign_f_pubkey(char *fingerprint, const char *pubkeyfile) {
 168         return usign_f(fingerprint, pubkeyfile, NULL, NULL);
 169 }
 170
 171 /*
 172  * call usign -F -s ...
 173  */
 174 int usign_f_seckey(char *fingerprint, const char *seckeyfile) {
 175         return usign_f(fingerprint, NULL, seckeyfile, NULL);
 176 }
 177
 178 /*
 179  * call usign -F -x ...
 180  */
 181 int usign_f_sig(char *fingerprint, const char *sigfile) {
 182         return usign_f(fingerprint, NULL, NULL, sigfile);
 183 }
 184
 185
 186 /*
 187  * call usign -V ...
 188  * return WEXITSTATUS or -1 if fork or execv fails
 189  */
 190 int usign_v(const char *msgfile, const char *pubkeyfile,
 191             const char *pubkeydir, const char *sigfile, bool quiet) {
 192         pid_t pid;
 193         int status;
 194         const char *usign_argv[16] = {0};
 195         unsigned int usign_argc = 0;
 196         char fingerprint[17];
 197
 198         if (usign_f_sig(fingerprint, sigfile)) {
 199                 if (!quiet)
 200                         fprintf(stderr, "cannot get signing key fingerprint\n");
 201                 return 1;
 202         }
 203
 204         if (pubkeydir && _usign_key_is_revoked(fingerprint, pubkeydir)) {
 205                 if (!quiet)
 206                         fprintf(stderr, "key %s has been revoked!\n", fingerprint);
 207                 return 1;
 208         }
 209         usign_argv[usign_argc++] = USIGN_EXEC;
 210         usign_argv[usign_argc++] = "-V";
 211         usign_argv[usign_argc++] = "-m";
 212         usign_argv[usign_argc++] = msgfile;
 213
 214         if (quiet)
 215                 usign_argv[usign_argc++] = "-q";
 216
 217         if (pubkeyfile) {
 218                 usign_argv[usign_argc++] = "-p";
 219                 usign_argv[usign_argc++] = pubkeyfile;
 220         }
 221
 222         if (pubkeydir) {
 223                 usign_argv[usign_argc++] = "-P";
 224                 usign_argv[usign_argc++] = pubkeydir;
 225         }
 226
 227         if (sigfile) {
 228                 usign_argv[usign_argc++] = "-x";
 229                 usign_argv[usign_argc++] = sigfile;
 230         }
 231
 232         pid = fork();
 233         switch (pid) {
 234         case -1:
 235                 return -1;
 236
 237         case 0:
 238                 if (execvp(usign_argv[0], (char *const *)usign_argv))
 239                         return -1;
 240
 241                 break;
 242
 243         default:
 244                 waitpid(pid, &status, 0);
 245                 return WEXITSTATUS(status);
 246         }
 247
 248         return -1;
 249 }