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 (
  76 #ifdef UCERT_HOST_BUILD
  77                         execvp(usign_argv[0], (char *const *)usign_argv)
  78 #else
  79                         execv(usign_argv[0], (char *const *)usign_argv)
  80 #endif
  81                    )
  82                         return -1;
  83
  84                 break;
  85
  86         default:
  87                 waitpid(pid, &status, 0);
  88                 return WEXITSTATUS(status);
  89         }
  90
  91         return -1;
  92 }
  93 #else
  94 int usign_s(const char *msgfile, const char *seckeyfile, const char *sigfile, bool quiet) {
  95         return -1;
  96 };
  97 #endif
  98
  99 /*
 100  * call usign -F ... and set fingerprint returned
 101  * return WEXITSTATUS or -1 if fork or execv fails
 102  */
 103 static int usign_f(char *fingerprint, const char *pubkeyfile, const char *seckeyfile, const char *sigfile) {
 104         int fds[2];
 105         pid_t pid;
 106         int status;
 107         const char *usign_argv[16] = {0};
 108         unsigned int usign_argc = 0;
 109
 110         if (pipe(fds))
 111                 return -1;
 112
 113         usign_argv[usign_argc++] = USIGN_EXEC;
 114         usign_argv[usign_argc++] = "-F";
 115
 116         if (pubkeyfile) {
 117                 usign_argv[usign_argc++] = "-p";
 118                 usign_argv[usign_argc++] = pubkeyfile;
 119         }
 120
 121         if (seckeyfile) {
 122                 usign_argv[usign_argc++] = "-s";
 123                 usign_argv[usign_argc++] = seckeyfile;
 124         }
 125
 126         if (sigfile) {
 127                 usign_argv[usign_argc++] = "-x";
 128                 usign_argv[usign_argc++] = sigfile;
 129         }
 130
 131         pid = fork();
 132         switch (pid) {
 133         case -1:
 134                 return -1;
 135
 136         case 0:
 137                 dup2(fds[1], 1);
 138
 139                 close(0);
 140                 close(2);
 141                 close(fds[0]);
 142                 close(fds[1]);
 143
 144                 if (
 145 #ifdef UCERT_HOST_BUILD
 146                     execvp(usign_argv[0], (char *const *)usign_argv)
 147 #else
 148                     execv(usign_argv[0], (char *const *)usign_argv)
 149 #endif
 150                    )
 151                         return -1;
 152
 153                 break;
 154
 155         default:
 156                 waitpid(pid, &status, 0);
 157                 status = WEXITSTATUS(status);
 158                 if (fingerprint && !WEXITSTATUS(status)) {
 159                         ssize_t r;
 160                         memset(fingerprint, 0, 17);
 161                         r = read(fds[0], fingerprint, 17);
 162                         if (r < 16)
 163                                 status = -1;
 164
 165                         fingerprint[16] = '\0';
 166
 167                 }
 168                 close(fds[0]);
 169                 close(fds[1]);
 170                 return status;
 171         }
 172
 173         return -1;
 174 }
 175
 176 /*
 177  * call usign -F -p ...
 178  */
 179 int usign_f_pubkey(char *fingerprint, const char *pubkeyfile) {
 180         return usign_f(fingerprint, pubkeyfile, NULL, NULL);
 181 }
 182
 183 /*
 184  * call usign -F -s ...
 185  */
 186 int usign_f_seckey(char *fingerprint, const char *seckeyfile) {
 187         return usign_f(fingerprint, NULL, seckeyfile, NULL);
 188 }
 189
 190 /*
 191  * call usign -F -x ...
 192  */
 193 int usign_f_sig(char *fingerprint, const char *sigfile) {
 194         return usign_f(fingerprint, NULL, NULL, sigfile);
 195 }
 196
 197
 198 /*
 199  * call usign -V ...
 200  * return WEXITSTATUS or -1 if fork or execv fails
 201  */
 202 int usign_v(const char *msgfile, const char *pubkeyfile,
 203             const char *pubkeydir, const char *sigfile, bool quiet) {
 204         pid_t pid;
 205         int status;
 206         const char *usign_argv[16] = {0};
 207         unsigned int usign_argc = 0;
 208         char fingerprint[17];
 209
 210         if (usign_f_sig(fingerprint, sigfile)) {
 211                 if (!quiet)
 212                         fprintf(stdout, "cannot get signing key fingerprint\n");
 213                 return 1;
 214         }
 215
 216         if (pubkeydir && _usign_key_is_revoked(fingerprint, pubkeydir)) {
 217                 if (!quiet)
 218                         fprintf(stdout, "key %s has been revoked!\n", fingerprint);
 219                 return 1;
 220         }
 221         usign_argv[usign_argc++] = USIGN_EXEC;
 222         usign_argv[usign_argc++] = "-V";
 223         usign_argv[usign_argc++] = "-m";
 224         usign_argv[usign_argc++] = msgfile;
 225
 226         if (quiet)
 227                 usign_argv[usign_argc++] = "-q";
 228
 229         if (pubkeyfile) {
 230                 usign_argv[usign_argc++] = "-p";
 231                 usign_argv[usign_argc++] = pubkeyfile;
 232         }
 233
 234         if (pubkeydir) {
 235                 usign_argv[usign_argc++] = "-P";
 236                 usign_argv[usign_argc++] = pubkeydir;
 237         }
 238
 239         if (sigfile) {
 240                 usign_argv[usign_argc++] = "-x";
 241                 usign_argv[usign_argc++] = sigfile;
 242         }
 243
 244         pid = fork();
 245         switch (pid) {
 246         case -1:
 247                 return -1;
 248
 249         case 0:
 250                 if (
 251 #ifdef UCERT_HOST_BUILD
 252                     execvp(usign_argv[0], (char *const *)usign_argv)
 253 #else
 254                     execv(usign_argv[0], (char *const *)usign_argv)
 255 #endif
 256                    )
 257                         return -1;
 258
 259                 break;
 260
 261         default:
 262                 waitpid(pid, &status, 0);
 263                 return WEXITSTATUS(status);
 264         }
 265
 266         return -1;
 267 }